A stretch composite fabric comprises a sintered expanded porous polytetrafluoroethylene film and a stretch cloth laminated to each other while maintaining a flat state. The stretch composite fabric has a tensile stress at 10% elongation, as measured in at least one direction, of 1.8 N/15 mm or less. When a 5 cm-width test piece of the stretch composite fabric is stretched in a length direction under a load of 300 g and then released from the stress, an elongation recovery R of the stretch composite fabric, which is given by the following equation, is preferably 70% or more. R=(L2−L3)/(L2−L1)×100 (In the equation, L1, L2, and L3 represent the lengths of the composite fabric before the load is applied, when the load is applied, and after the load is removed, respectively.)

A composite fabric comprising an expanded porous polytetrafluoroethylene (ePTFE) film and a cloth laminated to each other has been put to practical use as, for example, a clothing material excellent in moisture permeability and windbreak performance in the field of outdoor products and the like. Further, a composite fabric comprising a composite film having a waterproof property improved by applying a resin with moisture permeability to an ePTFE film and a cloth laminated to each other has also been put to practical use as, for example, a clothing material excellent in moisture permeability and waterproof property in the field of outdoor products and the like. A composite fabric comprising an ePTFE film alone is characterized by being excellent in moisture permeability and has been used as a material suitable for windbreakers or heavy winter clothes although the waterproof property of the composite fabric comprising an ePTFE film alone is inferior to that of a composite fabric comprising the composite film. In such composite fabrics, in order to increase a stretch property, a composite fabric comprising a composite film and a stretch cloth laminated to each other has also been known (Patent documents 1 and 2, etc.).
For example, in Patent document 1, a composite film comprising an expanded PTFE (i.e., sintered ePTFE) film and a hydrophilic elastomer layer provided by the technique described in U.S. Pat. No. 3,953,566, or a composite textile comprising this composite film and a fibrous outer layer (cloth) is stretched and released, whereby the stretch property and recovery property of this composite film or composite textile are increased. In this Patent document 1, the composite film or composite textile is stretched in one direction until a grip-to-grip distance of 9 inches becomes 18 inches (i.e., to about twice its original length), and at this time, necking occurs such that the sample width is decreased to about ⅜ to ½. When the present inventor made an additional test for this Patent document 1, the stretch property was not sufficient. Patent document 2 also describes that sintered PTFE as used in Patent document 1 "is poor in ductility because fibrils are fused to one another and interfibrillar slip does not occur" and points out that "the stretch property of the counterpart of the laminate is inhibited by the above-mentioned sintered PTFE and the stretch property of the laminate on the whole is hardly obtained".
Accordingly, Patent document 2 has proposed that PTFE is used without being sintered (unsintered as such). Patent document 2 describes that when a stretch resin is impregnated into an unsintered ePTFE film and retained therein, favorable restoring property and stretch property can be achieved. However, the unsintered ePTFE film to be used in this Patent document 2 has a low cohesive strength in a thickness direction, therefore, a delamination phenomenon is likely to occur. In order to avoid the occurrence of this delamination phenomenon, it has been proposed that a stretch resin is applied to one surface or both surfaces. However, when such a stretch resin is applied to one surface, a cohesive strength of a surface without application of the stretch resin is apparently lacking. Further, even when the stretch resin is applied to both surfaces, if pores remain in the inside of the ePTFE film, the cohesive strength at the region is lacking. In order to completely prevent the occurrence of the delamination phenomenon, it is necessary to completely impregnate the stretch resin into the inside of the ePTFE film, inevitably resulting in increasing the thickness of the resin layer and decreasing the moisture permeability.
Further, because the methods described in Patent documents 1 and 2 utilize the stretch property of a resin to be applied to ePTFE, the methods cannot be applied to a composite fabric comprising an ePTFE film alone.
As described above, it is difficult to achieve both stretch property and strength (cohesive strength) in the prior art. Accordingly, in Patent documents 3 to 5, a method of laminating an ePTFE composite film to a cloth is improved instead of improving the physical property of an ePTFE composite film. That is, in these Patent documents 3 to 5, a stretch cloth is laminated to an ePTFE composite film in a stretched state, and thereafter, the stretch cloth is shrunk. FIG. 1 is a schematic cross-sectional diagram of such a laminate. As shown in FIG. 1, in examples of Patent documents 3 to 5, a pleated structure in which an ePTFE composite film 1a is corrugated along the stretching and shrinking direction of a cloth 2 is adopted. By adopting this pleated structure, the ePTFE composite film 1a follows the stretching of the cloth while eliminating the pleats when the cloth is stretched, therefore, a stretching stress does not act on the ePTFE composite film 1a, and even if sintered ePTFE is used (even if a strength is secured), the stretch property is not sacrificed. When such a pleated structure is adopted, however, the ePTFE composite film 1a has a corrugated form, therefore, the aesthetic appearance of a laminate 3 is deteriorated. In addition, the laminate 3 is likely to be rubbed against other members at tops 10 of the corrugated pattern, and the laminate 3 is liable to be damaged. Further, a used amount of the ePTFE composite film per unit area of the laminate is increased, and the production cost is increased.
The present invention has been made in view of the circumstances as described above and has its object to establish a technique capable of increasing a strength and a stretch property of an ePTFE film without corrugating the film.    Patent document 1: JP-A-S59 (1984)-187845    Patent document 2: JP-A-S61 (1986)-137739    Patent document 3: JP-A-H03 (1991)-90352    Patent document 4: JP-A-S60 (1985)-139444    Patent document 5: JP-T-1409 (1997)-500844

Stretch composite fabric and expanded porous polytetrafluoroethylene film


A stent delivery system includes a stent having at least one eyelet and at least one rivet and a holder supporting the stent, wherein the holder includes a first section having a first diameter and a second section having a second diameter. A sheath covers the stent and the holder. The rivets are attached to each of the eyelets. A first inner diameter of the stent at the position of the rivets is smaller than a second inner diameter of the stent at other positions because the rivets protrude inwardly. A shoulder is formed on the holder due to the difference between the first diameter and the second diameter of the holder. The shoulder is positioned distally adjacent the rivets. The shoulder interferes with the protruding rivets, thereby restraining the longitudinal movement of the stent relative to the holder. Although the sheath is pulled back, the stent does not jump out of the stent delivery system. As a result, the stent delivery system allows the stent to be released in a controlled manner upon its deployment.

1. Field of Invention
The present invention relates to a stent delivery system. More particularly, the present invention relates to a stent delivery system that allows a stent to be released in a controlled manner upon its deployment.
2. Description of the Prior Art
Stents are well known and widely used in medical procedures. Stents are frequently used to treat various organs and vessels in the vascular system. In particular, stents are most commonly used to treat vascular diseases using endovascular procedures. Patients who suffer from vascular diseases typically develop stenosis of various arteries, i.e., blood vessels that are clogged or narrowed by substances that restrict blood flow. Traditionally, operations such as bypass surgery have been performed to treat the stenosis of arteries. Bypass surgery involves opening of the chest cavity, which is a very invasive procedure for patients.
The development of fluoroscopy was one of the first uses of non-invasive medical procedures. Fluoroscopy allows medical personnel to see internal organs and blood vessels of a patient from outside of the patient's body. Fluoroscopy is typically performed by introducing a catheter into a bodily passageway of the patient, for example, through one of the vessels in the leg. The catheter is a surgical instrument for withdrawing fluid from or introducing fluid or various medical devices into the body of a patient. In fluoroscopy, contrast media is introduced into the vessel that is to be observed. The catheter and the contrast media used in such procedures are well known in the art and are only described here generally for background.
After the contrast media is introduced and delivered through the blood vessel of the patient, physicians are able to see the state of the vessel. By using X-ray, physicians are able to spot possible areas of stenosis in the blood vessel. Once a narrowed portion of a blood vessel is identified, a stent is introduced to the spot of the clogged or narrowed blood vessels in order to provide a structural support. The stent generally expands within the vessel until it contacts the vessel wall. However, if the stenosis of the vessel is particularly acute, for example, greater than fifty percent, or if the substance causing the stenosis is calloused, the stent may not be able to fully expand. In those situations, a balloon is inserted to predilate the vessel. Upon implantation, the stent provides permanent structural support so that the blood vessel remains dilated. Using stents has the distinct advantage of providing both patients and physicians with a non-invasive method of treating problems of internal organs and blood vessels over traditional surgery.
Two types of the stents are generally employed: balloon-expandable stents and self-expandable stents. Although balloon-expandable stents have been used prior to introduction of the self-expandable stents, both types of the stents are currently used by physicians, depending on the area to be treated, the size of the vessel lumen, the state of the stenosis and the physician's experience and preference. For example, balloon-expandable stents are often preferable for treating critical arteries that are unlikely to experience pressure from external traumas. One of the advantages of balloon-expandable stents is that the implanted diameter of the stent can be precisely controlled. However, a disadvantage of balloon-expandable stents is that they can be catastrophically deformed when force from an external trauma is applied to the stent. As a result, the balloon-expandable stents are well suited for coronary vessels as opposed to peripheral vessels, which are frequently subject to external traumas.
With balloon-expandable stents, a balloon with a stent mounted thereon is introduced through a catheter and is inflated at the site of the narrowed vessel. The stent expands until it contacts and presses against the vessel wall. In contrast, self-expandable stents are capable of expanding without the use of a balloon. Self-expandable stents are generally made of spring metal, for example, nitinol or stainless steel. Spring metal used for making self-expandable stents typically has shape memory characteristics. Self-expandable stents are readily deformable by pressure applied thereto but return to their original shape like a spring after the pressure is removed.
Accordingly, a typical procedure for implanting a self-expandable stent is as follows. First, the stent is delivered to the vessel area to be treated through a catheter in a compressed or collapsed state. In order to keep the stent compressed during delivery, a stent delivery system having a sheath and a holder is used. In general, the sheath is an outer cover and the holder is located inside the sheath. The sheath and the holder typically have a tubular shape. The self-expandable stent is interposed between the sheath and the holder. The sheath applies pressure to the stent, thereby maintaining the stent in the collapsed state. The holder supports and carries the stent until it is released from the stent delivery system. The stent delivery system is loaded into the catheter and delivered to the vessel where the stent is to be deployed.
Second, once the stent is positioned at the area to be treated, the stent is implanted by releasing the stent from the delivery system. To release the stent, the sheath is retracted so that the stent is exposed to the vessel. A holder band is typically positioned at the proximal end of the stent. The holder band basically prevents the stent from moving rearward as the sheath is retracted. Because the sheath directly contacts and presses against the stent, the stent has a tendency to move backward as the sheath. Thus, the holder band can restrain such movement of the stent, thereby allowing the stent to be released as the sheath is retracted. Once the sheath is withdrawn, the stent is freed from pressure and starts to expand. After the stent fully expands, the stent delivery system and the catheter are removed from the vessel.
The description of balloon-expandable stents and self-expandable stents is provided for general background only. However, regardless of the type of the stent that is used, physicians have many different preferred procedures and variations for implanting stents. Further, the techniques used for implanting stents are still developing and changing. In addition, procedures usually associated with one type of the stent may also be used with different types of the stents.
During the process of deploying a stent, a conventional stent delivery systems have difficulty in properly positioning the stent. As described above, the sheath first retracts to expose the stent. During that process, the stent may act like a spring. As a result, the stent may jump out of the sheath and be starting to expand. This problem most commonly occurs where the stent is a short stent. Short stents may quickly expand before the sheath is fully retracted. Once the stent starts to expand, it is not possible to compress the stent back into the delivery system in order to reposition the stent. Also, it is difficult to adjust the position of the stent once the stent contacts the wall of the vessel. Accordingly, a stent delivery system is desirable that is able to release a stent in a controlled manner upon deployment.
Currently, most stent delivery systems on the market do not have a controlled release mechanism. Accordingly, physicians must exercise extreme caution by slowly deploying the stent so that the distal end of the stent has time to contact the vessel wall before the proximal end of the stent exits the sheath. This method is inherently unreliable and is susceptible to uncontrolled release of the stent during deployment.
In U.S. Patent Publication Nos. 2002/0120322 and 2002/0120323, a similar problem was addressed. In these patent publications, an interlock system that engages male interlock structures on the stent with female interlock structures on an inner tubular member is described. As shown in FIG. 6A of the Publications, the male interlock structures are positioned at the proximal and distal ends of the stent. The female interlock structures are formed to receive and be engaged with the male interlock structures. When the stent is in the collapsed state, the male and female interlock structures are coupled to each other.
When the sheath is retracted, the stent remains in the collapsed state until it is fully exposed. As the stent expands radially, the male interlock structures are free to radially move out of the female structures. By using this interlock system, it is possible to prevent the stent from moving longitudinally during expansion of the stent. However, this interlocking system adds extra costs in manufacturing the male and female interlocking structures. The male and female interlocking structures need to fit into each other accurately. Considering the size of the stent, the addition of male and female interlocking structures may require costly and burdensome processes. In addition, the stent may be subject to additional friction due to the interlocking structures. For example, if the interlocking structures are engaged with each other too tightly, the stent may be hindered from moving out of the stent delivery system.
U.S. Pat. No. 6,077,295 discloses a self-expandable stent delivery system. The system allows a physician to recapture a partially deployed stent. The physician can partially deploy the stent, and if the position of the stent is incorrect, the physician can manipulate control handles so that the sheath and the holder of the stent delivery system move axially in opposite directions. Specifically, the control handles can be manipulated so that the holder moves in a proximal direction, whereas the sheath moves in a distal direction. This system works on the assumption that it is possible to perform accurate manipulation of the control handles. However, it is uncertain that physicians can accurately manipulate the control handles once the stent is partially deployed. Thus, this system is still prone to errors in positioning the stent during deployment.

Stent delivery system allowing controlled release of a stent


A catalyst is preparable from a first component represented by R′C(CF2R)O−Q+ and a second component (NCCFR″)bZ. The catalyst may be combined with a fluoropolymer having nitrogen-containing cure-sites to form a curable composition that is useful for preparing fluoroelastomer compositions.

Fluoroelastomer compositions are particularly useful as seals, gaskets, and molded parts in systems that are exposed to elevated temperatures and/or corrosive materials. For sealing applications that require resistance to the most extreme conditions, perfluorinated elastomers are used. Such parts are used in applications such as automotive, chemical processing, semiconductor, aerospace, and petroleum industries, among others.
Curable compositions used to make fluoroelastomer compositions often include a fluoropolymer comprising monomer units having a nitrogen-containing cure site to facilitate cure in the presence of a curative. One class of useful cure-site components used in fluoroelastomers includes nitrogen-containing groups such as, for example, nitrites and imidates.
Fluoroelastomer compositions are typically prepared by combining a fluoropolymer resin or gum (sometimes referred to in the art as a fluoroelastomer gum) with one or more curatives to form a curable composition, shaping the curable mixture into a desired shape, and then curing the curable composition until the desired physical properties are achieved. During mixing of the curative(s) and fluoropolymer resin, and in subsequent handling prior to the curing step, the curable mixture may undergo a degree of premature curing (sometimes referred to in the art as incipient curing) that renders the curable composition difficult or impossible to shape. This premature curing is typically accompanied by a viscosity increase, and is referred to in the elastomer curing art as "scorch". Typically, scorch is reported with reference to "Mooney scorch" which is a measure of the incipient curing characteristics of a rubber compound using the Mooney viscometer. Mooney scorch is typically determined according to a standard test method such as, for example, ASTM D1646-04 "Standard Test Methods for Rubber-Viscosity, Stress Relaxation, and Pre-Vulcanization Characteristics (Mooney Viscometer)".
In general, the lower the degree of observed scorch, the greater will be the processing window during manufacture of shaped fluoroelastomer articles.

Catalyst for making fluoroelastomer compositions and methods of using the same


A brake pressure regulation method and system for a trailer vehicle, which is connected to a tractor vehicle having an electronically controlled pressure-medium brake renders sensing of the forces between the tractor and the trailer vehicle and, to this extent, also a corresponding force-recording apparatus superfluous. The method can be used advantageously in tractor vehicles equipped with an ABS. The method is based on transmission of wheel speed signals from the trailer vehicle to the tractor vehicle and brings about an adjustment of the brake pressure relation between the tractor and the trailer vehicle to the same average speed of the wheels of non-driven axles of the vehicle by correcting the brake pressure for the trailer vehicle adaptively to give braking work which can be distributed in optimum fashion to the tractor vehicle and the trailer vehicle. Since, in this way, the average utilization of adhesion at braked wheels of the trailer vehicle is the same as that at the non-driven, braked wheels of the tractor vehicle, not only is an increase in directional stability during braking achieved but also an advantageous evenness of the brake lining wear on the tractor vehicle and the trailer vehicle. The method can also be carried out very advantageously in conjunction with electronically controlled pressure-medium ABS brake systems for trailer vehicles.

The present invention relates to a brake pressure regulation method and system for a trailer vehicle which is connected to a tractor vehicle having an electronically controlled pressure-medium brake. The term "trailer vehicle" should here be taken to refer both to drawbar trailers and to semitrailers.
In vehicle combinations with conventional air brake systems, prescribed retardation bands are used in an attempt to achieve uniform participation of the tractor and the trailer vehicle in the braking work, i.e. the braking action both of the tractor and of the trailer vehicle must lie within certain band limits in relation to the pressure at the trailer connection used as a reference. These limits are relatively wide taking into account various limitations of conventional brake systems. In practice, this then leads in some cases to brake force distributions exhibiting a considerable error, especially in the range of the frequently occurring adaptive braking operations at a relatively low deceleration level. This results, inter alia, in extreme differences between the tractor and the trailer vehicle as regards the brake lining wear.
In electropneumatic brake systems, i.e. electrically/electronically controlled brake systems with wheel brakes actuated by compressed air, so-called coupling-force control systems are used in an attempt to improve the ratios. The function of these control systems is to detect "incorrect" brake pressure distributions and to influence the trailer control valve situated in the tractor in such a way that the forces between the tractor and the trailer vehicle are minimized.
German Offenlegungsschrift 3,901,270, for example, discloses an air brake arrangement for motor vehicles in which a sensor is arranged at a mechanical connection device for the vehicles in order to balance the braking action between the tractor and the trailer. The sensor measures the forces which occur at the connection device and controls a correction valve which is connected to the trailer supply line. Control is exercised via a control unit in which a control algorithm is installed to record and modify a pressure value and to emit signals which can be used to set a particular pressure in the trailer brake line.
German Auslegeschrift 2,164,325 also describes an apparatus for regulating the braking force at the wheels of motor vehicle trailers by influencing the pressure of the brake fluid for the trailer. This influence is exerted as a function of certain signals of a measuring element provided in the connection between the tractor vehicle and the trailer in order to measure the force occurring there. However, coupling-force sensors for rough conditions, as required by this apparatus or arrangement and by corresponding braking methods, are expensive and have to be continuously checked.
It is therefore an object of the present invention to provide a brake pressure regulation method for a trailer vehicle which is connected to a tractor vehicle having an electronically controlled pressure-medium brake which manages without sensing the forces between the tractor and the trailer vehicle. It is thus possible to dispense with corresponding coupling-force sensors and to have a method universally applicable, especially in conjunction with modern, electronically controlled power brake systems with ABS in tractor vehicles.
These objects have been achieved in a method for brake pressure regulation on a trailer vehicle including the steps of
(a) obtaining wheel speed signals from non-driven wheels of the tractor vehicle and of the trailer vehicle;
(b) transmitting at least one signal representative of at least the wheel speeds of one axle of the trailer vehicle to the tractor vehicle;
(c) cyclically processing, together with wheel speed signals from the tractor vehicle, the at least one signal, representative of at least the wheel speeds of one axle of the trailer vehicle, in the electronic control unit, including
(d) continuously forming and updating a sliding average (ds.sub.U) of an instantaneous relative difference (ds.sub.A) between average wheel speeds of non-driven wheels of the tractor vehicle and of the trailer vehicle in the unbraked condition from the beginning of a journey;
(e) in the case of a braking operation, calculating and making available the brake pressure for the trailer vehicle (P.sub.trail), starting from a fixed starting value (PHIA.sub.o) representative of the tractor vehicle for a brake pressure relation between the tractor vehicle and the trailer vehicle, as a product of a reference brake pressure of the tractor vehicle (P.sub.tractor) and a pressure relation coefficient (PHIA);
(f) after the beginning of the braking operation, calculating the actual retardation (Z.sub.actual) from the speed (V.sub.VA) of non-driven wheels of the tractor vehicle;
(g) as braking continues, making a check, by analyzing the trailer brake pressure (P.sub.trail), the instantaneous relative difference (ds.sub.A) between average wheel speeds of non-driven wheels of the tractor vehicle and of the trailer vehicle and the actual retardation (Z.sub.actual), to determine whether a steady-state braking phase is present;
(h) making a check to determine whether a difference (dds) between the instantaneous relative difference (ds.sub.A) between average wheel speeds of non-driven wheels of the tractor vehicle and of the trailer vehicle over said steady state braking phase and the unbraked updated sliding average thereof (ds.sub.U) has a larger absolute value than a threshold value EPSILON;
(i) if a steady-state braking phase is present and EPSILON is exceeded, then, calculating a change (dPHIA) in the brake pressure relation between the tractor vehicle and the trailer vehicle, this change being proportional to the current difference (dds) between said instantaneous relative difference (ds.sub.A) between average wheel speeds of non-driven wheels of the tractor vehicle and of the trailer vehicle and the unbraked updated sliding average thereof (ds.sub.U);
(j) adding the change (dPHIA) to the previous value (PHIA.sub.o, PHIA); and
(k) storing the resulting pressure relation coefficient (PHIA) adapted in the foregoing steps as the new pilot control value for distributing the brake pressure between the tractor vehicle and the trailer vehicle for the current journey.
Accordingly, the method of the present invention advantageously renders superfluous apparatus for detecting the coupling force between the tractor vehicle and the trailer vehicle since control is performed such that the mean utilization of adhesion at the axles of the trailer vehicle is as great as at those of the tractor vehicle. This aim is achieved by transmission of wheel speed signals from the trailer vehicle to the tractor vehicle since, in this way, the speeds of the wheels of all the axles are in the end adjusted to the same, if required normalized, mean value, and the brake pressure for the trailer vehicle is corrected or updated to give optimum distribution of the braking work between the tractor vehicle and the trailer vehicle.
Starting from a fixed initial value for the brake pressure distribution between the tractor and the trailer vehicle, an adaptive predetermination of the correct distribution of the braking force and, to this extent, the relation between the brake pressure level in the tractor vehicle and that in the trailer vehicle is taken as the basis for each current control intervention. This advantageously minimizes the necessity for current interventions in the range of customary retardations. For this purpose, the respectively expedient braking force distribution is determined and stored as a function of the retardation level demanded by the driver at the brake pedal even before the occurrence of large wheel speed differences between the axles of the tractor and the trailer vehicle, and is adapted (i.e. corrected) in the course of subsequent braking demands to the respective current requirements.
Generally speaking, the method according to the present invention makes it possible to use existing wheel speed transmitters of a tractor-trailer combination in order, on one hand, to provide possible balanced wear and, on the other hand, optimum utilization of the total braking capacity of the tractor vehicle and the trailer vehicle. Furthermore, the present invention has the advantage of minimizing the number of critical or highly stressed signal transmitters and their necessary connection paths to an electronic control unit in the tractor vehicle. To this extent, the method also brings about a considerable increase in the reliability of a corresponding brake system.

Tractor/trailer brake pressure regulation method and system


A high-voltage diode and a method for producing the high-voltage diode involve only three masking steps. Only three masking steps are required due to the use of adjustment structures and of a chipping stopper with an edge passivation containing a-C:H or a-Si. In this manner, the high-voltage diode is inexpensive to manufacture. The diode has a rating for reverse voltages of, in particular, above about 400 V and preferably above about 500 V, and can be fabricated with the least possible process complexity and thus a small number of photo technologies and, in the edge region, can readily be equipped with a channel stopper for avoiding leakage currents and a chipping stopper for limiting the extent of saving defects.

Field of the Invention
The present invention relates to a high-voltage diode having a well-type zone of a first conductivity type, which is provided in a first main surface of a semiconductor body having a second conductivity type, being opposite to the first conductivity type. A metal contact is provided on the well-type zone. A rear side metallization is located, opposite to the metal contact, on a second main surface of the semiconductor body. The second main surface is located opposite to the first main surface and an edge termination with a channel stopper is provided. A passivation layer, which is provided on the first main surface in a region between the metal contact and the channel stopper, covers a pn junction issuing at the first main surface.
To date, high-voltage diodes, which are provided for relatively high voltages of, in particular, above about 400 V, have been provided, and use planar structures, with edge terminations containing field plates, field rings, dielectric insulating layers, semi-insulating coverings and a varying doping in the edge region. In this case, these measures are employed individually or in combination, it perfectly well being the case that, by way of example, field plates, field rings and dielectric insulating layers are also used jointly.
In this case, it has been shown that, during the fabrication of the diode, even more steps are necessary for an edge termination that satisfies the requirements made of it than for setting the desired on-state and switching properties. Thus, by way of example, diode edges based on field plates require relatively complicated fabrication processes.
Specifically, in the reference by C. Mingues and G. Charitat, titled xe2x80x9cEfficiency of Junction Termination Techniques vs. Oxide Trapped Chargesxe2x80x9d, 1997 IEEE International Symposium on Power Semiconductor Devices and ICs, Weimar, pages 137 to 140, edge terminations with field rings, semi-insulating layers or a junction termination extension (JTE) are compared with one another especially with regard to their sensitivity to oxide charges. In this case, the use of SIPOS techniques is recommended as semi-insulating layers for high-voltage applications.
European Patent EP 0 341 453 B1, corresponding to U.S. Pat. No. 4,954,868, discloses a MOS semiconductor component for a high reverse voltage, in which field plates are disposed on insulating layers of different thicknesses. In this case, some of the field plates serve as channel stoppers. In diodes, such field plates used as channel stoppers are often connected to the rear side potential of the diode by a p-conducting region in the edge region, even though a connection via an n-conducting region would inherently be more advantageous because a p-conducting channel could thereby be reliably prevented. However, given an otherwise customary fabrication process, an additional mask step would be necessary for such a connection via an n-conducting region.
When sawing a wafer into individual chips, so-called chipping stoppers are intended to prevent crystal defects from propagating from the sawing edge into the active region of the respective chips. The chipping stoppers are usually realized by a field oxide between the functional edge region of the chip and the sawing line.
If pn junctions having a high blocking capability are only covered with dielectric passivation layers, then under the action of external charges which are attributable for example to moisture, alkaline or metallic contamination, etc., changes in the long-term blocking stability can be observed in the event of blocking loading of the pn junction. These changes are brought about by a drift of ionic charges in the electric field of the reverse-biased pn junction on or in the passivation layer. Depending on the sign of the ionic charges and also depending on the structure of the edge termination, that is to say depending on the so-called edge contour, the ionic charges can lead to an increase or to a decrease in the blocking capability of the pn junction. In the case of a diode with a p-conducting anode, in this case, as the doping in the n-conducting base decreases and therefore as the bulk blocking capability of the diode increases, as a result of a greater induction effect, the influence of such surface charges in and on the passivation layer increases, which leads to a dramatic increase in the risk of blocking instabilities. In this connection, reference should be made to the so-called Yoshida effect; when using insulator layers for passivation, a drift in the reverse voltage is occasionally observed on account of an injection of hot electrons during the on-state loading when changing over to the blocking state of the pn junction.
By using semi-insulating layers directly on the pn junctions, the influence of such surface charges can be suppressed given suitable settings of the layer and interface parameters, such as, for example, of the layer thickness and doping of the semi-insulating layers. The semi-insulating layers which are currently used for the passivation of pn junctions contain, for example, amorphous silicon (a-Si) or hydrogen-doped amorphous carbon (a-C:H), as are described in European Patents EP 0 400 178 B1 and EP 0 381 111 B1 (corresponding to U.S. Pat. No. 5,039,358). With these semi-insulating layers, parasitic effects, such as an elevated reverse current or the formation of inversion layers, can be avoided given corresponding optimization of the amorphous-crystalline heterojunctions between the layers and the electrically active silicon substrate. Moreover, semi-insulating passivation layers can actively build up image charges by virtue of their finite state density and thus shield extraneous charges that penetrate externally, and also dissipate injected charge carriers by virtue of their finite specific conductivity. Overall, a semi-insulating passivation thus leads to a significantly improved long-term stability compared with a dielectric passivation.
It is accordingly an object of the invention to provide a high-voltage diode and a method for fabricating the high-voltage diode that overcomes the above-mentioned disadvantages of the prior art devices of this general type, which has a rating for reverse voltages of, in particular, above about 400 V and preferably above about 500 V, and can be fabricated with the least possible process complexity and thus a small number of photo technologies and, in the edge region, can readily be equipped with a channel stopper for avoiding leakage currents and a chipping stopper for limiting the extent of saving defects; moreover, the intention is to provide a method for fabricating such a high-voltage diode.
With the foregoing and other objects in view there is provided, in accordance with the invention, a high-voltage diode. The diode contains a semiconductor body having a first main surface and a second main surface disposed opposite the first main surface, the semiconductor body is formed of a second conductivity type being opposite to a first conductivity type. A well-type zone of the first conductivity type is disposed in the first main surface of the semiconductor body. A metal contact is disposed on the well-type zone. A rear side metallization is disposed on the second main surface of the semiconductor body and disposed opposite to the metal contact. An edge termination having a channel stopper is provided. A passivation layer is disposed on the first main surface in a region between the metal contact and the channel stopper. The passivation layer covers a pn junction issuing at the first main surface. The passivation layer contains an amorphous carbon doped with hydrogen or an amorphous silicon and serves as a chipping stopper in a region of the semiconductor body outside the channel stopper. At least one edge is provided as an alignment structure disposed in the first main surface in a region of the well-type zone.
The measures of producing the masking insulating layer on the semiconductor body and the patterning of the mask insulating layer for the purpose of producing at least one window for the well-type zone each serve individually per se to enable a high-voltage diode which can be fabricated with a low outlay for masks and alignment and has a channel stopper, chipping stopper, etc. These measures can advantageously be employed jointly. It goes without saying, however, that it is also possible to provide a high-voltage diode that realizes only one of these measures.
The high-voltage diode according to the invention may be a fast diode exhibiting switching strength or, alternatively, a rectifier and universal diode in various voltage and current classes. The high-voltage diode may have one or a plurality of field rings depending on the desired voltage class in its edge region.
Preferably, in the case of the high-voltage diode according to the invention, the semiconductor body contains n-conducting silicon into which a p-conducting well-type zone is introduced.
Instead of an n-conducting silicon body, however, it is also possible to provide a p-conducting silicon body having an n-conducting well-type zone.
The semiconductor material is not limited to silicon. Instead of silicon, it is also possible to use, by way of example, SiC or an AIIIBv semiconductor material.
In accordance with an added feature of the invention, the edge termination has at least one field ring.
In accordance with an additional feature of the invention, the channel stopper is provided on the semiconductor body. More specifically, the channel stopper is preferably provided on a region of the first conductivity type.
In accordance with a further feature of the invention, a field stop layer of the second conductivity type is disposed between the semiconductor body and the rear side metallization. A doped emitter layer of the second conductivity type is disposed between the semiconductor body and the rear side metallization being a cathode metallization.
In accordance with another feature of the invention, the alignment structure is one of a plurality of alignment structures, the alignment structures contain silicon steps in the first main surface with a height of between about 10-1,000 nm, preferably with a height of between about 50-200 nm.
In accordance with another additional feature of the invention, the alignment structures are located outside the metal contact being an anode contact.
In accordance with another further feature of the invention, the semiconductor body has a sawing edge, and the passivation layer does not reach as far as the sawing edge.
In accordance with a further added feature of the invention, an annular zone of the first conductivity type, being uncovered at the first main surface, is disposed in a region of the sawing edge.
In accordance with a further additional feature of the invention, the well-type zone is doped with a dose of 1.3-3xc3x971012 dopant atoms cmxe2x88x922 to operate the high-voltage diode as a fast freewheeling diode. The well-type zone has a surface region doped with a dose of between 1.3xc3x971012 dopant atoms cmxe2x88x922 and 5xc3x971013 dopant atoms cmxe2x88x922.
In accordance with a concomitant feature of the invention, the edge termination has a plurality of field rings.
With the foregoing and other objects in view there is provided, in accordance with the invention, a method for fabricating a high-voltage diode. The method includes the steps of:
(a) producing a mask insulating layer on a semiconductor body;
(b) patterning the mask insulating layer resulting in a patterned mask insulation layer and windows, at least one of the windows provided for a well-type zone;
(c) producing steps functioning as alignment structures in the semiconductor body through the windows;
(d) producing the well-type zone through the window with in each case a first conductivity type opposite to a second conductivity type of the semiconductor body;
(e) removing the patterned mask insulating layer;
(f) applying and patterning a passivation layer using a lithography step aligned using the alignment structures resulting in a patterned passivation layer with further windows, the passivation layer is made from amorphous carbon doped with hydrogen or amorphous silicon;
(g) applying and patterning a metal contact and a channel stopper in the further windows of the patterned passivation layer on a front side of the well-type zone and of the semiconductor body respectively; and
(h) applying a metallization on a rear side of the semiconductor body.
In accordance with an added mode of the invention, there is the step of patterning the mask insulating layer for use in forming a field ring and a chipping stopper ring during method step (b).
In accordance with an additional mode of the invention, at least one of the following steps is performed before or after method step (d):
(i) thinning by grinding and/or etching of the semiconductor body to a final thickness;
(j) introducing a doping of the second conductivity type for forming a field stop layer on the rear side of the semiconductor body and outdiffusing the doping;
(k) introducing an n-conducting doping on the rear side of the semiconductor body as a rear side emitter using ion implantation;
(l) introducing heavy metal atoms for setting a charge carrier lifetime; and
(m) diffusing the heavy metal atoms.
In accordance with another mode of the invention, there is the step of performing one of the method steps (l) and (m) before or after method step (d).
In accordance with a further mode of the invention, there is the step of carrying out the method steps (i) to (k) after method steps (l) and (m) are completed.
In accordance with a further added mode of the invention, there is the step of carrying out the following method step after method step (e) and before method step (f):
(n) irradiating at least one of the semiconductor body and the well-type zone and rings contained therein for setting the charge carrier lifetime.
In accordance with a further additional mode of the invention, the following method step is carried out after method step (f) and before method step (g):
(o) irradiating at least one of the semiconductor body and the well-type zone and rings contained therein for setting the charge carrier lifetime.
In accordance with another added mode of the invention, at least one of the following method steps is carried out after method step (g):
(p) heat treating a front side metallization made of the metal contact and the channel stopper; and
(q) irradiating the semiconductor body and the zone and rings contained therein for setting the charge carrier lifetime.
In accordance with another additional mode of the invention, there is the step of carrying out method steps (i) and (k) after method step (q).
In accordance with another further mode of the invention, there is the step of carrying out the following method step after method step (h):
(r) heat treating the metallization on the rear side of the semiconductor body.
In accordance with an added mode of the invention, there is the step of forming the mask insulating layer in a furnace process with moist oxidation up to a layer thickness of about 0.5 xcexcm.
In accordance with an additional mode of the invention, there is the step of introducing the alignment structures into the semiconductor body by etching down to a depth between 10-1,000 nm, preferably to a depth between 50-200 nm. Preferably, an isotropic etching is used for the etching.
In accordance with a further mode of the invention, there is the step of providing the alignment structures with a spacing with respect to the windows.
In accordance with a concomitant feature of the invention, there is the step of carrying out only three phototechnology steps for fabricating the high-voltage diode.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a high-voltage diode and a method for fabricating the high-voltage diode, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

Eupec Europaeische Gesellschaft fuer Leistungshalb-Leiter mbH and Co. KG


According to one disclosed embodiment, a transistor gate is fabricated on a substrate. For example, the gate can be a polycrystalline silicon gate in a FET. Thereafter, a conformal layer is deposited over the substrate and the gate and is then etched back to form spacers on the sides of the gate. An underlying dielectric layer is formed on the substrate, gate, and spacers. The conformal layer and the underlying dielectric layer can be comprised of, for example, a dielectric such as silicon dioxide, silicon nitride, or a low-k dielectric. Next, an overcoat layer is fabricated on the underlying dielectric layer. The overcoat layer can be, for example, polycrystalline silicon. Following, an opening is etched in the overcoat layer and the underlying dielectric layer wherein subsequent films can be grown. For example, silicon germanium can be grown in the opening for fabrication of a silicon germanium heterojunction bipolar transistor.

1. Field of the Invention
The present invention is generally in the field of fabrication of semiconductor devices. More specifically, the invention is in the field of fabrication of various layers related to HBT transistors in semiconductor devices.
2. Related Art
A technique often employed in the fabrication process for semiconductor devices involves creating an opening in a certain region of various layers or the substrate in the semiconductor device in order to deposit or grow other materials in the opening. For example, one of the steps in constructing a silicon germanium heterojunction bipolar transistor (xe2x80x9cSiGe HBTxe2x80x9d) requires opening a targeted region in a layer of oxide and growing a film of SiGe in the opening to serve as the transistor base. Conventional methods for creating such an opening have proven less than satisfactory.
FIG. 1 depicts structure 10 which is used to illustrate problems associated with depositing a relatively thick film over the semiconductor substrate and opening a certain region in the film. In this example, creation of an opening is needed so that SiGe can be grown in the opening to complete fabrication of an NPN HBT transistor. Certain details and features have been left out of FIG. 1 which are apparent to a person of ordinary skill in the art. Structure 10 includes components of a field effect transistor (xe2x80x9cFETxe2x80x9d), in this instance a P-channel field effect transistor (xe2x80x9cPFETxe2x80x9d), and a NPN HBT that are still under construction.
As seen in FIG. 1, structure 10 includes collector 12 for a SiGe NPN HBT. Collector 12 has top surface 14. Buried layer 16, which is composed of N+type material, is formed in silicon substrate 17 in a manner known in the art. Collector sinker 18, also composed of N+type material, is fonned by diffusion of heavily concentrated dopants from the surface of collector sinker 18 down to buried layer 16. Deep trench structures 22 and field oxide structures 24, 25, 26, and 28, composed of silicon dioxide (xe2x80x9cSiO2xe2x80x9d) material. are formed in a manner known in the art. Deep trench structures 22 and field oxide structures 24, 25, 26, and 28 provide electrical isolation from other devices on silicon substrate 17 in a manner known in the art.
Structure 10 of FIG. 1 also includes features and components of a CMOS device, such as a P-channel field effect transistor, or PFET, on the same wafer as the NPN HBT. Structure 10 includes N well 32 for a PFET. Structure 10 further includes source 34 and drain 35. Structure 10 also includes gate oxide 36 and gate 38, which in this example is polycrystalline silicon. Both gate oxide 36 and gate 38 are formed in a manner known in the art.
It is additionally seen in FIG. 1 that thick conformal layer 42 is deposited on the semiconductor surface, and additional conformal overcoat layer 44 is deposited on thick conformal layer 42. Conformal layer 42 can be a dielectric material known to those skilled in the art and may be, for example, SiO2 or silicon nitride. Overcoat layer 44 can consist of, for example, polycrystalline silicon. Opening 45 with width 48 is the result of an etching process that etches thick conformal layer 42 and overcoat layer 44 selectively down to top surface 14. Etching can be done by a method known in the art such as a hydrogen fluoride (xe2x80x9cHFxe2x80x9d) wet etch. Some problems with this approach are that HF is an isotropic etcher, i.e. it etches in all direections, and further a lengthy etch time is required to etch through thick conformal layer 42. These problems cause undercutting in thick conformal layer 42. These problems and the resulting undercutting they produce leave width 48 of opening 45 uncertain, and most often, larger than intended.
Continuing with FIG. 1, the uncertainty in size of width 48 of opening 45 create by the undercutting of thick conformal layer 42 means that any subsequent film deposited in opening 45 will be of indeterminate dimensions. An example would be the epitaxial growth of SiGe film 46 in opening 45 to serve as the base for an HBT. Undercuts 47 result in lack of control of critical physical dimensions in the SiGe HBT. such lack of control in turn results in undesirable electrical properties. For example, for certain applications, the base-collector parasitic capacitance can be undesirably increased. As another example, in certain applications control over precise dimensions of the SiGe HBT base can be impaired. Whenever there is imprecision in building the SiGe HBT. performance is compromised. Thus, when undercutting occurs from the etching step such that the dimensions of width 48 of opening 45 are uncertain the SiGe HBT will not perform optimally. Another problem caused by the undercutting is the difficulty in trying to implant, for example, dopants in certain regions of the deposited film that are obscured by the undercut.
Creating an opening in a relatively thin layer of material does not present the level of undercutting associated with creating an opening in a relatively thick layer. For example, when an opening is needed in a thin layer of a-dielectric film, the etch time necessary to etch through the relatively thin dielectric layer is comparatively brief, and the short etch time keeps undercutting to a minimum. Unfortunately, a different problem arises with thin layers. FIG. 2 shows the difficulties encountered with having to create an opening in a thin conformal film. Structure 20 of FIG. 2 is similar to structure 10 of FIG. 1 and has the same device components that make up structure 10 in FIG. 1. In addition, thin conformal film 52 is deposited over silicon substrate 17 and its various regions such as the field oxide regions. and forms a thin conformal film. Conformal overcoat 54 is deposited on thin conformal film 52. Opening 55 with width 58 has been etched through overcoat 54 and thin conformal film 52, down to top surface 14 in a manner known in the art.
The etch time necessary to etch through thin conformal film 52 is relatively short, and minimal undercutting occurs. The significant reduction in undercutting means that the dimensions of width 58 of opening 55 can be controlled with greater precision, and any subsequent material deposited in opening 55 will have dimensions that are better controlled. FIG. 2 further has SiGe film 56 grown over thin conformal layer 52 and conformal overcoat 54. It is seen that SiGe film 56 also grows in opening 55 where it assumes width 58. In the present example, control of the dimensions of the grown SiGe layer is critical to the performance of the HBT. Because undercutting of conformal layer 52 is minimal, the dimensions of SiGe film 56 grown in and close to opening 55 can be controlled much more precisely. When creating an opening in a relatively thin film, the uncertainty in the dimensions of subsequent materials deposited or grown in the opening created in a thick layer is avoided.
While creating an opening in thin conformal layer 52 causes minimal undercutting, FIG. 2 shows that other problems develop with this process. Because of the relative thinness of thin conformal film 52 where it deposits on gate 38, the subsequent depositing of conformal overcoat 54 at gate 38 produces a sharp edge or cusp at the upper coerners of gate 38. It is seen in FIG. 2 that the: growth of SiGe film 56 on gate 38 is non-conformal and produces a non-ideal property of deposition. This non-ideal property of deposition is also referred to as non-isotropic deposition. In the present example, the non-isotropic deposition of SiGe leads to a phenomenon called xe2x80x9cbreadloafingxe2x80x9d. Breadloafing occurs where the non-conformal film, in this case SiGe film 56, wraps around the sharp edges of conformal overcoat 54 at the upper corners of gate 38, and extends beyond the upper corners of gate 38, producing a profile resembling a slice of bread.
Continuing with FIG. 2, overhangs 57 characterize breadloafing and create crevices 51 beneath them and along the sidewalls of gate 38. Crevices 51 are the chief cause of problems associated with depositing material in an opening created in a relatively thin film. With overhangs 57 present, subsequent films deposited on SiGe film 56 can accumulate in crevices 51. When these subsequent films are removed in an etching step or other photolithography process, overhangs 57 function as a mask, preventing the etchant from reaching film materials trapped beneath. The materials trapped beneath overhangs 57 and in crevices 51 are thus unintentionally left behind and form what are termed xe2x80x9cstringersxe2x80x9d. FIG. 2 shows stringers 59 trapped beneath overhangs 57 and in crevices 51 following an etching step intended to remove all films deposited on SiGe film 56. Furthermore when it becomes necessary to etch the SiGe film 56 itself. these stringers micromask and prevent etching of the SiGe trapped beneath them.
The existence of stringers during semiconductor fabrication can detrimentally affect semiconductor performance. For instance, stringers are sometimes very conductive because the film material from which they are derived is conductive, and the presence of conductive material in unintended places can affect the electrical profile and function of nearby devices.
Thus it is seen that a method is needed that will improve the ability to open certain regions on the substrate surface for further fabrication of the semiconductor. More specifically, a method is needed that will permit creating openings without the undercutting or breadloafing produced by conventional methods and that will prevent the non-ideal deposition of subsequent films.
The present invention is directed to a method for opening a semiconductor region for fabricating a heterojunction bipolar transistor. The method of the present invention results in an improvement of the ability to open certain regions on the substrate surface for further fabrication of the semiconductor. More specifically, the invention""s method permits creating openings without the, undercutting or breadloafing produced by conventional methods and will aid in proper deposition of subsequent films.
According to the method of the present invention, a transistor gate is fabricated on a substrate. For example, the transistor gate can be a polycrystalline silicon gate in a FET. Thereafter, a conformal layer is deposited over the substrate and the transistor gate. For example, conformal layer can be any suitable dielectric such as silicon dioxide, silicon nitride, or a low-k dielectric. The conformal layer is then etched back so as to form spacers on the sides of the transistor gate. Subsequently, an underlying dielectric layer is formed on the substrate, the transistor gate, and the spacers on the transistor gate. The underlying dielectric layer can be, for example silicon dioxide or other suitable dielectric material such as silicon nitride or a low-k dielectric.
Next, an overcoat layer is fabricated on the underlying dielectric layer. The overcoat layer can be, for example, polycrystalline silicon. Once the overcoat layer has been formed, an opening is etched in the overcoat and underlying dielectric layers. Subsequent films can be deposited in the opening etched in the overcoat and underlying dielectric layers. For example, silicon germanium can be grown in the opening for the purpose of fabricating a silicon germanium heterojunction bipolar transistor.

Method for opening a semiconductor region for fabricating an HBT


Stable boron resins of high selective absorbent power, their production process, and processes of using said boron resins. The boron resins include a polyacrylic matrix functionalized with quaternary ammonium groups, an epoxy group and phenylboric groups in accordance with general formula (I): ##STR1## in which P, R, R.sub.1, R.sub.2, R.sub.3, Y and X.sup.- are as defined in the text. The resin is prepared by condensing an acrylic resin with an epihalohydrin and then with a halide or hydroxide of an oxiphenyl-aminophenyl- or thiophenyl-boroxin or their alkyl derivatives. Compared with similar currently known resins, the resins of formula (I) have improved selectivity in sugar preparation. They can be used for purifying lactulose.

This invention relates to new boron resins possessing very high selective absorbent power which are stable in organic solvents and in aqueous acid and alkaline solutions.
More particularly, the invention relates to boron resins consisting of an acrylic polymer matrix functionalized with quaternary ammonium groups, an epoxy group and phenylboric groups of general formula (I): ##STR2## in which:
P is a polyacrylic matrix,
R is --(CH.sub.2).sub.n -- where n lies between 0 and 5,
R.sub.1 and R.sub.2, which can be the same or different, are C.sub.1 -C.sub.5 alkyl,
R.sub.3 is --(CH.sub.2).sub.n -- where n varies from 1 to 5,
Y is --O--, --S--, ##STR3## where R is a C.sub.1 -C.sub.5 alkyl, and
X.sup.- is an anion chosen from halogens and hydroxyl;
The invention also relates to a process for producing the boron resins defined by general formula (I).
In European Patent 8510934.8 we have already described boron resins with a polyacrylic matrix bifunctionalized with quaternary ammonium groups and alkylphenylboric groups, which possess good chemical and mechanical stability characteristics and can be used in industrial processes, they having a marked selective absorbent action particularly in separating lactulose from its mixtures with other carbohydrates, generally lactose and galactose.
It has now been discovered that boron resins with further improved selectivity in separating sugars can be obtained by the process of the present invention, which is described in detail hereinafter.

Boron resins of high selective absorbent power


The present invention discloses an embedded and test mode timer circuit that is used to perform operations in an embedded mode and a plurality of test modes in a memory device. When the memory device is operating in the embedded mode, the embedded and test mode timer circuit is activated to automatically direct at least one logic circuit to execute logic tasks at predetermined times. When the memory device is operating in a test mode, the embedded and test mode timer circuit is activated to automatically direct a portion of the logic circuits to execute logic tasks at predetermined times and the remaining portion of the logic circuit are manually directed.

The present invention relates generally to non-volatile memory devices and, more particularly, to a timing system and method for embedded and test modes within flash electrically erasable programmable read-only memory (EEPROM) devices.
A flash memory is a storage device that is capable of retaining stored information in the absence of continuous power. The information is stored in a plurality of flash transistors that are electrically connected and formed on a silicone substrate. A flash transistor is typically referred to as a memory cell and includes a source, a drain, a floating gate and a control gate. Flash memory are formed by rows and columns of memory cells that form a memory array. The memory array is typically a matrix where the control gates of the memory cells in a row are electrically connected to form a respective wordline and the drains of the memory cells in a column are electrically connected to form a respective bitline. Generally, the sources of the memory cells are electrically connected to form a common source line.
To perform a read, program or erase of memory cells in the memory array, a respective predetermined voltage is applied to the wordlines, bitlines and source lines of the memory cells. In addition to the read, program and erase, other typical operations performed on the memory cells are a program verify and an erase verify. The program verify ensures that the memory cells have been properly programmed and the erase verify ensures that the memory cells have been properly erased. If memory cells are not properly programmed or erased, corrective actions are taken by the flash memory to achieve the desired programmed or erased state.
The process of reading, programming, program verifying, erasing or erase verifying memory cells in the flash memory are typical operations that involve a number of logic tasks. The logic tasks can be performed in what is known by those skilled in the art as an embedded mode in the flash memory. In the embedded mode, the logic tasks associated with an operation are automated such that once the operation is initiated the logic tasks will be executed automatically in a synchronized fashion by the flash memory.
In addition to the embedded mode, the flash memory typically also includes a plurality of test modes where the read, program, program verify, erase and erase verify operations are performed during testing of the flash memory. Prior art systems and methods of performing an operation in the test modes involves manual application of externally supplied control signals to execute the logic tasks. Since the timing of some of the logic tasks is critical or must occur very quickly, known problems can occur unless the testing is done using expensive and sophisticated test equipment.
Prior art testing is very complex and requires that the test equipment is programmed to maintain the timing and synchronization of the logic tasks during the operations. The test equipment is also required to supply predetermined magnitudes of control signals to the flash memory. In addition, a change to the operations in the embedded mode of the flash memory typically requires changes to the programming and control voltages of the test equipment.
For the foregoing reasons, a need exists for memory devices that can perform operations in both the embedded mode and test modes without the use of expensive and sophisticated test equipment.
The present invention discloses a memory device that includes an embedded and test mode timer circuit to perform operations in both the embedded mode and a plurality of test modes. The preferred memory device is a flash memory and includes a state machine electrically connected with an embedded and test mode timer circuit. The embedded and test mode timer circuit and the state machine are also electrically connected with at least one logic circuit. As known in the art, the state machines are used to control the overall operation of the flash memory in response to instruction sets that are received by the state machine.
During an embedded mode in the preferred embodiment, the state machine receives instruction sets and activates the embedded and test mode timer circuit. As known in the art, the embedded mode is a mode that allows automated operation of the flash memory. The embedded and test mode timer circuit is activated to automatically direct the logic circuits to execute an operation such as a read, program, program verify, erase or erase verify based on a plurality of predetermined times. During a plurality of test modes, the state machine activates the embedded and test mode timer circuit to automatically direct a portion of the logic circuits at predetermined times and manually direct the remaining logic circuits.
The preferred embedded and test mode timer circuit includes a timer electrically connected with a plurality of decoders that are in turn electrically connected with at least one flip-flop. The flip-flops are electrically connected with the logic circuits. During the embedded mode, when the state machine receives instructions to perform an operation, the state machine activates the timer and a portion of the decoders. The portion of the decoders activated is a decoder group that is associated with, and controls, the operation to be performed. The timer generates and directs a plurality of predetermined times to the decoders. As the timer counts sequentially, the decoders in the decoder group monitor the timer and generate a plurality of control output signals that are directed to the flip-flops when a respective predetermined time is reached. The control output signal from each decoder in the decoder group activates the flip-flops to direct the logic circuits to perform a plurality of logic tasks to complete the operation.
When an operation such as a program, a program verify, an erase, an erase verify or a read is performed during a test mode, the state machine activates the embedded and test mode timer circuit to direct the logic circuits. The timer and the same decoder group that are associated with the operation in the embedded mode are activated. However, in the test mode, the timer and decoder group does not control all the logic circuits associated with the operation. The timer and the decoder group activate the flip-flops to direct a portion of the logic circuits and the remaining logic circuits are manually controlled. Effectively, the logic circuits for the test mode operation are split into three groups: 1) those logic circuits that are automatically directed to execute logic tasks at the beginning of the operation; 2) those logic circuits that are manually directed to execute logic tasks in the middle of the operation; and 3) those logic circuits that are automatically directed to execute logic tasks at the end of the operation. As would be recognized by those skilled in the art, the nature and number of logic tasks in each respective group are dependent on the particular operation within the test mode.
The state machine manually controls the logic circuits by activating the flip-flops within the embedded and test mode timer circuit to direct the logic circuits based on user control inputs to the flash memory. When the operation is initiated in the test mode, the logic circuits are directed by the timer, the decoder group and the flip-flops to automatically execute the logic tasks at the beginning of the operation based on the predetermined times generated by the timer. The logic circuits that include the logic tasks in the middle of the operation are no longer automated since the respective decoders are disabled and the operation is effectively suspended until they are completed manually. The user manually activates the flip-flops in the embedded and test mode timer circuit to direct the logic circuits to execute the logic tasks in the middle of the operation. Following completion of the logic tasks in the middle of the operation, the logic circuits are automatically directed to execute the logic tasks at the end of the operation by the timer, the decoder group and the flip-flops.
Those skilled in the art recognize that determining which logic tasks are placed in manual user control and which logic tasks remain automated by the timer as in the embedded mode is dependent on the operation being performed during the test mode. In addition, the decision of which logic tasks within a particular test mode operation are to be placed in manual control is dependent on what types of tests are to be performed.
Another preferred embodiment of the present invention, is a method of executing an operation in an embedded mode and in a plurality of test modes in a memory device that in the preferred embodiment is a flash memory. The operation is initiated with a state machine. The state machine then activates an embedded and test mode timer circuit to execute the operation. The embedded and test mode timer directs a plurality of logic circuits to complete the operation in both the embedded mode and the test modes in the same manner as in the previously set forth embodiments.
Presently known prior art memory timing architectures use timers for operations performed in the embedded mode and manually control operations in the test mode using expensive and sophisticated test equipment. The preferred embodiment of the present invention utilizes the timer and the same decoder group for an operation in either the embedded mode or the test mode. Since the test mode operation is performed using the embedded and test mode timer circuit and the state machine, the complexity of testing is greatly reduced thus avoiding the use of expensive and sophisticated test equipment.
In the preferred embodiment, the timing for the logic tasks where timing is critical, or must occur very quickly, is the same in both the embedded mode and during the test modes. Since the timing is the same, changes to the flash memory that affect the operation in the embedded mode also affect the operation in the test modes. In addition, since the critical timing is accomplished with the timer and decoders, manual direction of the logic circuits with the embedded and test mode timer circuit and the state machine can be accomplished with simple test equipment.

Integration of embedded and test mode timer


A software implementation and method for garage ventilation control logic to intelligently modulate the rate of speed of a plurality of garage fan motors in an enclosed commercial parking garage structure. The savings are primarily driven by the known cubic relationship between fan power draw and fan speed, whereby fans operating at lower speeds will draw much less power than operating at higher speeds, taking advantage of the highly non-linear relationship between the two.

Most enclosed parking garage structures today are subject to ventilation standards established by the International Mechanical Code (IMC). In North America, such structures are further subject to the rules established by the American Society of Heating, Refrigeration and Air Conditioning (ASHRAE). Both governing bodies stipulate garage ventilation systems must run continuously during building occupied hours. The only instance in which continuous ventilation of the garage is not required is when the property owner deploys a Demand-Control Ventilation System which monitors such gases as Carbon monoxide (CO) and/or Nitrogen dioxide (NO2).
With California serving as a model for the remaining 49 states, research shows roughly 35% of commercial garages that possess a mechanical ventilation system deploy a CO-sensor-based demand-control ventilation (DCV) system. NO2 detection and control is required in enclosed garages wherever a certain, minimum percentage of diesel-based vehicle traffic is anticipated.
Of the installed base of garage ventilation control systems in California, for example, the majority of these systems fall in the category of binary on/off systems, which activates the garage fan motors to ventilate the garage only when increased CO levels require it. The typical threshold point for on/off control is when CO levels equal or exceed 25 parts per million (ppm) before the fan motor units are activated to provide ventilation.
Deployment of a binary on/off CO systems creates as many issues as it does solutions. For Example, the California Utilities Statewide Codes and Standards Team noted a common problem that, due to their simplistic design, a significant percentage of binary on/off CO sensor systems installed throughout the years had "failed off," meaning a sensor had become inoperable but without any indication of sensor failure and with possible consequences to system energy consumption and garage air quality. In fact, according to field inspection studies, the failure rate of such systems was shown to be as high as 90%.
The unintended consequence is to create health and safety risks for commercial garage workers and visitors alike, as well as for those who live and/or work above a below-grade parking facility, with gas concentrations rising to unhealthy levels in most commercial garages without anyone being aware of the issue.
Additionally, it is critical to consider the impact of an "on/off" CO sensor ventilation control strategy on peak electric power draw, which influences the cost of peak demand charges from regional electric utilities. The time most garage-fan motors are likely turn on is during peak demand periods (roughly from noon to 6 p.m., depending on the utility and the region). This is also when most people leave work, and cold starts are when cars emit the highest concentration(s) of hazardous gases, before an automobile's catalytic converter has warmed up sufficiently to be effective.
The potential to incur peak energy (kW) demand charges occurs when a significant number of cars start simultaneously, like at quitting time for example, causing emissions to exceed hazardous gas "trip point" levels and thus ramp the garage fan motors to their full speeds. Should the garage-fan motors be on at the time the local utility is monitoring peak demand consumption, the property owner may be hit with high peak demand charges not only for that day, but also the entire month in many utility districts.
Due to the drawbacks presented by the incumbent "on/off" CO sensor systems, a small number of states, including California, have adopted stricter (than the IMC/ASHRAE standards) garage ventilation requirements. Specifically, they require continuous ventilation in the garage even when a CO and/or NO2 DCV system is in place.
An increasing number of other states have or are moving toward revising their respective Energy Codes to reflect stricter standards, including the requirement for continuous ventilation. It is anticipated that, over time, each of the 50 states and Canada will require continuous ventilation in enclosed, commercial garages even when CO (and/or NO2) sensor-based DCV system is deployed. In response, the marketplace has taken incremental steps toward introducing other methods of enclosed garage ventilation to meet the new standards, but it has been done from the standpoint of adherence versus a focus on innovation.

System and method for garage ventilation control logic


A new tracking technique is essentially xe2x80x9csourcelessxe2x80x9d in that it can be used anywhere with no set-up, yet it enables a much wider range of virtual environment-style navigation and interaction techniques than does a simple head-orientation tracker. A sourceless head orientation tracker is combined with a head-worn tracking device that tracks a hand-mounted 3D beacon relative to the head. The system encourages use of intuitive interaction techniques which exploit proprioception.

This invention relates to self-referenced tracking.
Virtual reality (VR) systems require tracking of the orientation and position of a user""s head and hands with respect to a world coordinate frame in order to control view parameters for head mounted devices (HMDs) and allow manual interactions with the virtual world. In laboratory VR setups, this tracking has been achieved with a variety of mechanical, acoustic, magnetic, and optical systems. These systems require propagation of a signal between a fixed xe2x80x9csourcexe2x80x9d and the tracked xe2x80x9csensorxe2x80x9d and therefore limit the range of operation. They also require a degree of care in setting up the source or preparing the site that reduces their utility for field use.
The emerging fields of wearable computing and augmented reality (AR) require tracking systems to be wearable and capable of operating essentially immediately in arbitrary environments. xe2x80x9cSourcelessxe2x80x9d orientation trackers have been developed based on geomagnetic and/or inertial sensors. They allow enough control to look around the virtual environment and fly through it, but they don""t enable the xe2x80x9creach-out-and-grabxe2x80x9d interactions that make virtual environments so intuitive and which are needed to facilitate computer interaction.
In one aspect, in general, the invention provides a new tracking technique that is essentially xe2x80x9csourcelessxe2x80x9d in that it can be used anywhere with no set-up of a source, yet it enables a wider range of virtual environment-style navigation and interaction techniques than does a simple head-orientation tracker, including manual interaction with virtual objects. The equipment can be produced at only slightly more than the cost of a sourceless orientation tracker and can be used by novice end users without any knowledge of tracking technology, because there is nothing to set up or configure.
In another aspect, in general, the invention features mounting a tracker on a user""s head and using the tracker to track a position of a localized feature associated with a limb of the user relative to the user""s head. The localized feature associated with the limb may include a hand-held object or a hand-mounted object or a point on a hand.
In another aspect, in general, the invention features mounting a sourceless orientation tracker on a user""s head and using a position tracker to track a position of a first localized feature associated with a limb of the user relative to the user""s head.
In another aspect, in general, the invention features tracking a point on a hand-held object such as a pen or a point on a hand-mounted object such as a ring or a point on a hand relative to a user""s head.
In another aspect, in general, the invention features using a position tracker to determine a distance between a first localized feature associated with a user""s limb and a second localized feature associated with the user""s head.
In another aspect, in general, the invention features a position tracker which includes an acoustic position tracker, an electro-optical system that tracks LEDs, optical sensors or reflective marks, a video machine-vision device, a magnetic tracker with a magnetic source held in the hand and sensors integrated in the headset or vice versa, or a radio frequency position locating device.
In another aspect, in general, the invention features a sourceless orientation tracker including an inertial sensor, a tilt-sensor, or a magnetic compass sensor.
In another aspect, in general, the invention features mounting a display device on the user""s head and displaying a first object at a first position on the display device.
In another aspect, in general, the invention features changing the orientation of a display device, and, after changing the orientation of the display device, redisplaying the first object at a second position on the display device based on the change in orientation.
In another aspect, in general, the invention features determining the second position for displaying the first object so as to make the position of the first object appear to be fixed relative to a first coordinate reference frame, which frame does not rotate with the display device during said changing of the orientation of the display device.
In another aspect, in general, the invention features displaying the first object in response to a signal from a computer.
In another aspect, in general, the invention features mounting a wearable computer on the user""s body, and displaying a first object in response to a signal from the wearable computer.
In another aspect, in general, the invention features displaying at least a portion of a virtual environment, such as a fly-through virtual environment, or a virtual treadmill, on the display device.
In another aspect, in general, the invention features displaying a graphical user interface for a computer on the display device.
In another aspect, in general, the invention features first object being a window, icon or menu in the graphical user interface.
In another aspect, in general, the invention features the first object being a pointer for the graphical user interface.
In another aspect, in general, the invention features changing the position of the first localized feature relative to the position tracker and, after changing the position of the first localized feature, redisplaying the first object at a second position on the display device determined based on the change in the position of the first localized feature.
In another aspect, in general, the invention features displaying a second object on the display device, so that after changing the position of the first localized feature, the displayed position of the second object on the display device does not change in response to the change in the position of the first localized feature.
In another aspect, in general, the invention features determining the second position so as to make the position of the first object appear to coincide with the position of the first localized feature as seen or felt by the user.
In another aspect, in general, the invention features changing the orientation of the first coordinate reference frame in response to a signal being received by the computer.
In another aspect, in general, the invention features changing the orientation of the first coordinate reference frame in response to a change in the position of the first localized feature.
In another aspect, in general, the invention features changing the orientation of the first coordinate reference frame in response to a signal representative of the location of the user.
In another aspect, in general, the invention features changing the orientation of the first coordinate reference frame in response to a signal representative of a destination.
In another aspect, in general, the invention features changing the orientation of the first coordinate reference frame in response to a signal representative of a change in the user""s immediate surroundings.
In another aspect, in general, the invention features changing the orientation of the first coordinate reference frame is changed in response to a signal representative of a change in the physiological state or physical state of the user.
In another aspect, in general, the invention features redisplaying the first object further comprises changing the apparent size of the first object according to the change in position of the first localized feature.
In another aspect, in general, the invention features mounting a portable beacon, transponder or passive marker at a fixed point in the environment and determining the position vector of a second localized feature associated with the user""s head relative to the fixed point.
In another aspect, in general, the invention features determining the position vector of the first localized feature relative to the fixed point.
In another aspect, in general, the invention features mounting a sourceless orientation tracker on a second user""s head and determining the position of a localized feature associated with the body of the second user relative to the fixed point.
In another aspect, in general, the invention features determining the position vector of a second localized feature associated with the user""s head relative to the fixed point without determining the distance between the second localized feature and more than one fixed point in the environment.
In another aspect, in general, the invention features displaying the first object at a third position after displaying the first object at the third position, changing the orientation of the display, and after changing the orientation of the display, continuing to display the first object at the third position.
In another aspect, in general, the invention features the first object being a window in a wraparound computer interface.
In another aspect, in general, the invention features redisplaying the changed position of the first localized feature not being within the field of view of the display when the first object is redisplayed.
In another aspect, in general, the invention features displaying the first object at a position coinciding with the position of the first localized object when the first localized object is within the field of view of the display.
In another aspect, in general, the invention features positioning the first localized feature at a first point positioning the first localized feature at a second point and calculating the distance between the first point and the second point.
In another aspect, in general, the invention features determining a position vector of the first localized feature relative to a second localized feature associated with the user""s head and modifying the position vector based on an orientation of the user""s head.
In another aspect, in general, the invention features setting an assumed position for the user""s head in a coordinate system and setting a position for the first localized feature in the coordinate system based on the assumed position of the user""s head and said position vector.
In another aspect, in general, the invention features measuring the orientation of the user""s head relative to a fixed frame of reference.
In another aspect, in general, the invention features setting a virtual travel speed and direction for the user modifying the assumed position for the user""s head based on the user""s virtual travel speed and direction.
In another aspect, in general, the invention features mounting on the head of a user a three degree of freedom orientation tracker for tracking the orientation of the head, and a three degree of freedom position tracker for tracking the position of a first localized feature on the user""s limb relative to a second localized feature on the user""s head, computing a position vector for the first localized feature relative to the second localized feature, determining a rotation matrix based on information received from the rotation tracker, and transforming the position vector into a position vector for a fixed frame of reference based on the rotation matrix.
In another aspect, in general, the invention features using an acoustic or radio frequency position tracker to track a position of a first localized feature associated with a limb of the user relative to the user""s head.
In another aspect, in general, the invention features mounting a video camera on the back of the user""s head and displaying an image generated by the video camera in a portion of a display device mounted on the user""s head.
In another aspect, in general, the invention features mounting a first inertial sensor on a user""s head, mounting a second inertial sensor elsewhere on the user""s body or in an object held by the user, and tracking the position of one inertial sensor relative to the other.
Some embodiments of the invention include sensing data at the first and second inertial sensors and using the sensed data to track the position of one inertial sensor relative to the other, tracking the position of the inertial sensor is done without reference to any signal received from a source not mounted on or held by the user and correcting the drift of the relative position or orientation of the second inertial sensor relative to the first inertial sensor by measurements between devices on the user""s head and devices elsewhere on the users body.
Among the advantages of the invention are one or more of the following. The device is easy to don, can track both head and hand, adds no new cables to a wearable computer system, works anywhere indoors or outdoors with no preparation, and is simpler than alternatives such as vision-based self-tracking.


A housing assembly of an OPC unit to protect an OPC drum in an image forming apparatus includes a main housing enclosing at least a half of a large-diameter OPC drum and provided with a main-opening selectively contacting a plurality of developing units and a plurality of sub-openings, a first housing and a second housing each mounted on a side of the main housing, a handle hingedly connected to the main housing, and a plurality of brackets mounted on opposite sides of the main housing. As a result, the housing assembly of the OPC unit allows easy development, electrification, exposure, image transfer and treatment of a waste toner, and reliability of the image developing process increases due to the fixation of the developing units. Also, since the exposure of the OPC drum is minimized, an area of the OPC drum to be contaminated can be reduced.

1. Field of the Invention
The present general inventive concept relates to a housing assembly of an organic photoconductive (OPC) unit, and in particular, to a housing assembly to protect an OPC drum on which an image to be printed is formed in an image forming apparatus.
2. Description of the Related Art
In general, an image forming apparatus, such as a copying machine, a printer, or a combined machine, is used for forming an image on an OPC medium and then printing the image on a recording medium. For example, a laser printer prints an image on a sheet of paper through a series of steps, e.g., forming a desired image on an OPC medium with a laser scanning unit (LSU) and then transferring a developed image onto a paper through an image transfer unit.
Such an image forming apparatus requires an OPC unit including an OPC medium for forming an image. For a mono-printer, a housing assembly of the OPC unit is typically formed in an integral structure to enclose not only an OPC drum but also a developing roller or the like.
A conventional housing assembly 10 of an OPC unit is described with reference to FIG. 1 by way of an example. The housing assembly 10 includes a main opening 14 through which an OPC drum 22 projects, and a sub-opening 12 that serves as an exposure window.
As shown in FIG. 1, the housing assembly 10 entirely protects toner, a toner stirrer 16 for supplying the toner, a toner feeding roller 18, a developing roller 20, an electrification roller 24, and an OPC drum 22.
The toner feeding roller 18 serves to transfer the toner to the developing roller 20 and is located adjacent to the developing roller 20, and the developing roller 20 is in contact with the OPC drum 22 with a developing nip or gap being formed between the developing roller 20 and the OPC drum 22, so that the developing roller 20 develops an image formed by a laser scan unit 26 with the toner received from the toner feeding roller 18 to form a developed image on the OPC drum 22.
As shown in FIG. 1, in general, the conventional housing assembly 10 is provided with a toner storage case 13 positioned higher than any of the developing roller 20 and the toner feeding roller 18, so that the toner can be moved by weight toward the developing roller 20 through the toner feeding roller 18.
However, such a housing assembly 10 for a mono image forming apparatus has a disadvantage in that it can not be employed in a color image forming apparatus provided with four respective color developers each for yellow, magenta, cyan and black.
In particular, in a color image forming apparatus of a multi-path type including one OPC medium and one image transfer medium, the OPC medium is developed while individually coming into contact with each developing unit in a state that a developing nip or gap is formed between the OPC medium and the developing unit. Therefore, it is not possible to employ such a construction of the conventional housing assembly that has been used in the conventional mono image forming apparatus provided with an developing roller, etc., in the color image forming apparatus, and it is required to develop a new housing assembly according to a novel concept.
Although a currently developed color image forming apparatus uses a hard type OPC drum, which is not a belt, it has to have a plurality of small-diameter OPC drums for colors and also a plurality of color developing units corresponding to the OPC drums. In the currently developed color image forming apparatus, an image is developed by the respective color developing units and transferred to a big-sized transfer belt from the respective OPC drums. Such a color image forming apparatus with the above construction is bulky and is manufactured at high costs.
In order to the solve the above problem, a method has been suggested, in which a plurality of movable developing units selectively contact one single small-diameter OPC drum one by one to develop a color image. However, this method has a problem of an unstable developing process because of the movable developing units, thereby losing reliability of a developing quality.
Alternatively, another method also has been suggested, which uses an OPC belt instead of the OPC drum. According to this method, a developing process is performed in a manner that respective color developing units are brought into contact with the OPC belt. However, it is difficult to maintain a constant tension of the OPC belt, and the OPC belt becomes loosened when being used for a predetermined time or a tension of the OPC belt attenuates, thereby causing a poor contact with the developing units.


A room protection mechanism for protecting access through a window or doorway includes a flexible barrier sheet adjustable between a collapsed, storage configuration, and a deployed configuration. The protection mechanism includes a housing storing the flexible barrier sheet in the collapsed configuration. Sheet magnetic elements are attached to the flexible barrier sheet, and structured to magnetically couple to frame magnetic elements mounted to a frame of the doorway or window. The protection mechanism can be deployed, such as in a school or other institutional setting, to position the flexible barrier sheet to block access through the doorway or window. The flexible barrier sheet may be formed of or include a ballistic material.

Protection of areas within a school or other institution is an acute challenge in modern society. The occurrence of intruders in schools, buildings, or other settings has motivated manufacturers and security authorities to propose a variety of counter measures in an effort to protect the lives and safety of individuals, notably children. Schools, for instance, are now typically equipped with various electronic monitoring systems to detect the presence or entry of intruders. Safety officers are also often employed to monitor the safety status of institutions, and take action as warranted.
Security systems have also been proposed, and some commercially implemented, that enable personnel at a central control station to remotely lock doors or other access points to buildings, hallways, and rooms. One security device is set forth in U.S. Pat. No. 9,702,664 to Rose, Jr. et al. and proposes a ballistic shade system for rolling up and down ballistic material and holding it in place during a ballistic event. Rose, Jr. et al. propose sidetracks forming channels designed to be mounted to the left and right of an opening in a wall. The sidetracks channel edges of ballistic material up and down and hold the edges in to ostensibly prevent their pushing out of the channel when a ballistic event hits the ballistic material. The design of Rose, Jr. et al. may have some applicability, but it is complex and appears relatively labor intensive to install.

Electromagnetically operated protection mechanism, system, and method