A circuit protection device includes a fuse element placed in parallel with a PTC thermistor layer. The element and PTC thermistor layer are provided on one or more insulating substrate, such as an FR-4 or polyimide substrate. First and second conductors connect the fuse element and PTC thermistor layer electrically in parallel, such that current (i) initially under normal flows mainly through the fuse element and PTC thermistor layer at a lower drop in voltage and (ii) after an opening of the fuse element flows under normal operation through the PTC thermistor layer at a higher drop in voltage.

The present disclosure relates generally to circuit protection and more particularly to overcurrent protection.
Fuses for printed circuit board ("PCB") level applications have in many cases been resettable type fuses. The reason is that in many cases, PCB's are heavily populated, making the disposal of an entire PCB due to an opened non-resettable fuse impractical. Replacing an opened non-resettable fuse is also impractical. The PCB may be buried in a machine, automobile, computer, etc., in such a manner that it is virtually impossible to reach. Even if reachable, the PCB may be in a device, e.g., computer, cellular phone or other hand-held device that is used by an individual, making servicing difficult and/or cost prohibitive.
One known resettable fuse that can be sized for PCB level applications is called a positive temperature coefficient ("PTC") device. PTC thermistor materials rely on a physical characteristic germane to many conductive materials, namely, that the resistivity of the conductive materials increases with temperature. Crystalline polymers made electrically conductive via the dispersement of conductive fillers therein, exhibit this PTC effect. The polymers generally include polyolefins such as polyethylene, polypropylene and ethylene/propylene copolymers. Certain doped ceramics such as barium titanate also exhibit PTC behavior.
The conductive fillers cause the resistivity of the PTC thermistor material to increase as the temperature of the material increases. At temperatures below a certain value, the PTC thermistor material exhibits a relatively low, constant resistivity. However, as the temperature of the PTC thermistor material increases beyond this point, the resistivity increases sharply with only a slight increase in temperature.
If a load protected by a PTC thermistor material is short circuited, the current flowing through the PTC thermistor material increases and the temperature of the PTC thermistor material (due to the above-mentioned i.sup.2R heating) rises rapidly to a critical temperature. At the critical temperature, the PTC thermistor material dissipates a great deal of power causing the rate at which the material generates heat to be greater than the rate at which the material can lose heat to its surroundings. The power dissipation only occurs for a short period of time (e.g., a fraction of a second). However, the increased power dissipation raises the temperature and resistance of the PTC thermistor material, limiting the current in the circuit to a relatively low value. The PTC thermistor material accordingly acts as a form of a fuse.
Upon interrupting the current in the circuit, or removing the condition responsible for the short circuit, the PTC thermistor material cools below its critical temperature to its normal operating, low resistance state. The result is a resettable overcurrent circuit protection material.
Even though the PTC thermistor materials operate at lower resistances under normal conditions, the normal operating resistances for PTC thermistor materials are higher than that of other types of fuses, such as non-resettable metallic fuses. The higher operating resistance results in a higher voltage drop across the PTC thermistor material than for similarly rated non-resettable metallic fuses. Voltage drop and power dissipation is becoming increasingly important to circuit designers, who are attempting to maximize the drive capability of a particular circuit as well as battery life.
Accordingly, an improved PCB level circuit protection device is needed. The present disclosure relates in general to circuit protection and more particularly to overcurrent protection. While overcurrent causing events are relatively rare, especially in certain types of devices, they can still occur and accordingly must be protected against. However, it has become apparent that because the short circuit causing events are relatively rare, a device and method adding a non-resettable, e.g., metallic, type fuse element having a lower operating resistance in parallel with one or more resettable, e.g., positive temperature coefficient ("PTC") thermistor, type fuse material provides a desirable overall circuit protection combination.
The parallel combination results in an overall combined or equivalent resistance of the device, which is even lower than the operating resistance of the metallic fuse element. In the unlikely event an overcurrent condition occurs, the metallic fuse element opens and the resistance of the PTC thermistor layer increases, limiting the current and thereby protecting the circuit. When the overcurrent condition or short circuit is removed, the PTC resistance decreases to its normal operating value and the circuit functionality is restored, albeit at a higher operating resistance than with the metallic fuse element intact. This approach offers the benefits associated with lower operating resistance until an overcurrent condition occurs, which in most cases will be the life of the circuitry since, as mentioned previously, overcurrent events are rare.
In one embodiment, therefore, a circuit protection device includes a fuse element placed in parallel with a PTC thermistor layer. The element and PTC thermistor layer are provided on one or more insulating substrate, such as an FR-4 material or polyimide substrate. First and second conductors connect the fuse element and PTC thermistor layer electrically in parallel, such that current (i) initially under normal operation flows through both the fuse element and the PTC thermistor layer causing a lower voltage drop, and (ii) after an opening of the fuse element flows under normal operation through the PTC thermistor layer causing a higher voltage drop.
As shown below, the PTC thermistor layer and metallic fuse element in one embodiment can be configured to have approximately the same time-current opening characteristic. The resulting combination time-current opening more closely tracks that of the PTC thermistor material, especially at higher currents. At lower currents, the combination time-current opening characteristic is slower than either the fuse element or PTC thermistor material. Alternatively, the PTC thermistor layer and metallic fuse element are chosen to have different ratings. For example, the PTC material can be chosen to have a lower rating than the metallic fuse element.
In one embodiment the PTC thermistor layer is polymer based. In an alternative embodiment, the PTC thermistor layer is ceramic. The ceramic-based integrated device can include a thin film type metallic fuse element or a wire fuse element as shown and described below. The ceramic-based device can be mounted via axially or radically disposed leads or be surface mounted.
The metallic fuse element is configured to provide desirable opening characteristics. For example, the metallic element, which can be copper, can be a surface-mounted element for which the length, thickness and/or height of the element is set to provide a desired opening characteristic. Also, a dissimilar metal such as a Metcalf spot can be employed to achieve a desired opening characteristic. The dissimilar metal can be any one or more of nickel, indium, silver and tin.
The fuse element is alternatively a wire fuse element that is single or multi-stranded. The wire can be of a single material or coated with a dissimilar metal. The wire element is bonded, e.g., soldered, to electrodes forming part of the first and second conductors.
The first and second conductors each include a pad or electrode extending to each of the metallic fuse element and PTC thermistor material. An electrode can for example be formed by a photolithographic processes onto the insulating substrate. A PTC thermistor layer is then applied over the electrode and exposed substrate. An electrode can run from a termination of one of the conductors across most of the substrate towards a termination of the second conductor. The length of the electrodes is sized to ensure good contact with the PTC thermistor layer and to allow the PTC thermistor material to function as desired.
In one embodiment, the fuse element is provided on one side of the insulating substrate, while the PTC element is provided on the opposite side of the substrate. In the case of a surface mounted device, the element can be formed by photolithographic processes, e.g., from a copper layer, to have a thin, opening portion and wider pad portions that extend to terminal pads forming initial layers of end terminations of the conductors. The copper pad is then plated with one or more layer, such as electrolytic copper and electrolytic tin. This plating operation forms vias or castellations to electrically connect the pads, electrode and fuse element on each end of the device. The fuse element in an embodiment is provided with a protective cover, such as an epoxy coating. The fuse element side of the overall device in an embodiment is configured to be mounted towards the PCB, so that energy released upon an opening of the element is contained between the device and the PCB.
The device in one embodiment includes a plurality of insulating substrates. For example, the fuse element can be located on the bottom side of a lower insulating substrate. A first conductor includes a first electrode applied (e.g., almost all the way across) to the topside of the bottom substrate. The PTC thermistor layer is then applied to the electrode and to any exposed top of the bottom substrate. A second insulating substrate having a second electrode, e.g., formed by photolithographic processes, on its bottom side is then applied to the top of the PTC thermistor layer. The second electrode extends to the second conductor.
The topside of the second insulating substrate includes copper terminal pads. The upper terminal pads are plated the same as the lower terminal pads in one embodiment. The device can therefore be mounted in either direction, for example, if it is determined in a particular instance that mounting the device with the fuse element towards the PCB risks harming the integrity of the connection of the device to the PCB when the fuse element opens.
The topside of the upper insulating substrate can also be marked with suitable indicia, such as rating indicia and manufacturer information. Again, in an embodiment, the fuse element is provided on the bottom side of the bottommost substrate.
In a further alternative embodiment, one or more additional PTC thermistor layer and insulating substrates are added in the manner described above to produce a device having an overall desired operating characteristic both when the metallic fuse element is intact and when the metallic fuse element has been opened. Adding PTC thermistor layers in general allows for the PTC side of the device to have a higher current rating and may need to be done to match the rating of the metallic fuse element.
In various embodiments, the device is provided in a 1206 (0.120 inch by 0.06 inch) and 1812 (0.180 inch by 0.120 inch) packages.
It is accordingly an advantage of the present disclosure to provide an improved overcurrent protection device.
It is another advantage of the present disclosure to provide a resettable overcurrent device having reduced internal resistance and operating voltage drop.
It is a further advantage of the present disclosure to provide a resettable overcurrent device having a metallic fuse element.
Additional features and advantages are described herein, and will be apparent from, the following Detailed Description and the figures.
As seen in FIGS. 2A and 2B, second copper layer 16 is etched away from insulating substrate 12 along the right side of device 10. In this manner, electrode 16 does not directly electrically contact a termination formed at the right side of device 10. A similar third copper layer or electrode 18 is etched onto the upper surface of insulating substrate 14. Here, electrode 18 makes contact with a termination formed on the right side of device 10 but does not directly electrically contact a similar termination formed on the left side of device 10. A fourth copper layer 20b is photo-etched away from the bottom side of insulating substrate 14 using standard photolithographic processes. As seen in the bottom of view FIG. 3 of device 10, copper layer 20b is etched to a specific shape to form the metallic fuse element of device 10. Lower copper layer 20b also extends to form a bottom-side base layer of terminations 36a and 36b.
Insulating substrates 12 and 14 having etched copper layers 16, 18 and 20a and 20b, respectively, are sandwiched about a positive temperature coefficient ("PTC") layer 30. One suitable PTC thermistor material for PTC thermistor layer is provided in a Polyfuse® LF1206L device marketed by eventual assignee of the present disclosure. This material is polymer-based. Ceramic configurations are discussed below.
PTC thermistor layer 30 in an embodiment is laminated initially between two large insulating substrates. Electrodes 16, 18, 20a and 20b are preformed on the large insulating substrates prior to their assembly, enabling many devices 10 to be formed from one assembled array. Device 10 is then singulated from the assembled array of insulating substrates and attached PTC thermistor layer via known separation or singulation techniques.
FIG. 3 illustrates that metallic fuse element 24 is formed on a bottom surface of insulating substrate 14 in one embodiment. Copper layer 20b is photo-etched to a specific shape to form the fuse element. Etched copper layer 20b includes pad areas 22a and 22b, which extend to element 24. Pad areas 22a and 22b also extend to larger termination areas 26a and 26b of copper layer 20b, which are eventually plated along with upper copper layer 20a to form terminations 36a and 36b. The base metal for fuse element 24 is therefore copper in one embodiment.
While device 10 is generally described as having photo-etched copper electrodes, it should be appreciated that electrodes 16, 18, 20a and 20b could be made of alternative metals and applied via a different process, such as an electroplating, sputtering, printing or laminating. Insulating substrates 12 can be made of a polyimide as opposed to an FR-4 material. Either way, electrodes 16, 18, 20a and 20b can be of one or more metal, such as silver, copper, nickel, tin and alloys thereof applied to the surface of the polyimide in any of the above-mentioned ways.
Element 24 has a height h, a length l and width w-sized to create a desirable opening characteristic for fuse element 24. Height h for example can be thinner at element 24 than the height of pads 22a and 22b and termination areas 26a and 26b. The thinned height h of element 24 in an embodiment is formed via a skiving or additional etching process. Element 24 is shown in FIG. 3 as having a generally straight length l. It should be appreciated however that element 24 can alternatively be jagged or curved, e.g., serpentine, to increase the distance 1 as needed to create a desirable opening characteristic for element 24.
Further, one or more dissimilar metal spot 28, sometimes referred to as a Metcalf spot, can be applied to element 24 at an area of the element desirable for the element to open, e.g., at the center of the element. Dissimilar metal spot 28 can be any one or more of nickel, indium, silver and tin. Dissimilar metal spot 28 has a lower melting temperature than that of the base metal of fuse element 24, e.g., copper. Low melting temperature spot 28 melts more quickly and diffuses into the base metal of element 24. The base and dissimilar metals are chosen such that the diffusion of one into the other results in an intermetallic phase with a lower melting temperature and higher resistance than the base metal, which forces the element to melt at lower level overcurrent levels, and prevents over-heating of the device.
A protective coating 32 is applied to fuse element 24 and a portion of fuse pads 22a and 22b as seen in FIGS. 2 and 3. Protective coating 32 in an embodiment is an electrically insulating epoxy, which is printed, sprayed or otherwise applied to the bottom side of insulating substrate 14 and copper layer 20b forming fuse element 24, pad areas 22a and 22b and termination areas 26a and 26b.
In an embodiment, device 10 is configured such that fuse element 24 is mounted towards the printed circuit board ("PCB"). Protective coating 32 and the downwardly disposed mounting configuration tend to confine the energy released from an opening of fuse element 24. It should be appreciated however that device 10 can operate alternatively with fuse element 24 mounted towards the PCB or away from the PCB.
FIG. 1 illustrates a top surface of device 10. Here, indicia 34 specifies rating and manufacturer information for device 10. Indicia 34 in an embodiment is applied to, e.g., printed onto, a top surface of upper insulating substrate 12.
Device 10 can be provided in various standard sizes, such as a 1206 package, which is 0.120 inch by 0.06 inch (3.2 mm) by (1.6 mm). Alternatively, device 10 can be provided in an 1812 package, which is approximately 0.179 inch by 0.127 inch (4.5 mm) times.(3.24 mm). It should be appreciated however that device 10 can be made larger or smaller as desired and to produce a device having a desired rating.
Terminations 36a and 36b are formed by standard plating techniques on the upper and lower surfaces of device 10 in the illustrated embodiment. Terminations 36a and 36b can be multiple layers of metal, such as electrolytic copper, electrolytic tin, silver, nickel or other metal or alloy as desired. Terminations 36a and 36b are sized and configured to enable device 10 to be mounted in a surface mount manner onto a PCB.
FIG. 2A illustrates a section A-A of FIG. 1 taken through the middle of device 10. Accordingly, element 24 and dissimilar metal spot 28 are seen in FIG. 2A. A pair of apertures 46 and 48 is made in insulating materials 12 and 14, for example, before device 10 is singulated from the device array. The plating of terminations 36a and 36b covers the sides of apertures 46 and 48. Accordingly, terminations extend along the sides of device 10 at the surfaces of apertures 46 and 48 as seen in FIG. 2A. When device 10 is singulated, terminations 36a and 36b do not extend along the straight sides of the device, e.g., do not extend along the straight sides of the device at section B-B of FIG. 1, as seen in FIG. 2B.
FIG. 4 illustrates an equivalent circuit for device 10 discussed above. The resistances shown in FIG. 4 are merely for the purposes of example and are in no way intended to limit the scope of the claims appended hereto. The resistances do, however, represent realistic values for the present device. Thus PTC thermistor layer 30 (or the combination of multiple PTC thermistor layers 30) is shown for example having a resistance of 0.070 Ohms. Fuse element 24 has a lower resistance of 0.031 Ohms. As seen in FIG. 4 and as should be appreciated from FIG. 2, PTC thermistor layer 30 and fuse element 24 are placed in electrical parallel with each other. According to the resistance equation for parallel devices, the equivalent resistance for device 10, E.sub.q equals the PTC resistance R.sub.at multiplied by the fuse resistance R.sub.f, which forms a product that is divided by the sum of R.sub.at plus R.sub.f. This equation yields an equivalent resistance in the example, R.sub.eq of 0.022 Ohms. The equivalent resistance is even less than the resistance of the metallic fuse element 24. Device 10 therefore has an initial low resistance operation. Device 10 also has the ability to reset itself through PTC thermistor layer 30.
According to the equivalent circuit of FIG. 4, the current will initially pass through fuse element 24 and PTC thermistor layer 30 until an overcurrent condition occurs, after which the current path through element 24 is opened and current is thereafter shunted in total under normal operation through PTC thermistor layer 30. It is believed that overcurrent events occur relatively infrequently, especially for certain applications using device 10, meaning that in many cases device 10 will operate without seeing an overcurrent condition throughout the entire life of the PCB. That is, many devices 10 will operate under low resistance and low voltage drop conditions throughout the entire life of the PCB. If however an overcurrent event does occur, device 10 maintains its functionality and the PCB onto which it is mounted does not have to be reworked or replaced. The original benefit of low resistance and voltage drop is lost but overall functionality remains.
Referring now to FIG. 5, results from testing of a device 10 for time-to-open versus current is illustrated. Three time-current curves are illustrated, one for metallic a fuse element 24 rated for two Amps, one for PTC thermistor layer 30 rated for two Amps and one showing the time-current curve for the two overcurrent components placed in parallel (combo). The combination line tends to follow that of PTC thermistor layer 30 and has a longer response time than that of either fuse element 24 or PTC layer 30.
The illustrated device 10 uses like rated fuse element 24 and PTC thermistor layer 30. Alternatively, device 10 can use a fuse element 24 and PTC thermistor layer 30 having different ratings. For example, PTC thermistor layer 30 could have a lower rating, e.g., 1.5 Amps, than the two Amps of fuse element 24. The resulting device 10 would have a quicker response time, e.g., for a data bus application described in more detail below. The telecommunications and battery applications described below might require a slower acting overall device 10.
Referring now to FIG. 6, results for four parts made according to the teachings in connection with device 10 for voltage drop versus current testing are illustrated. The plot illustrates that the voltage drop for the four parts was relatively repeatable, especially to about two Amps. Afterwards, the parts begin to show a slight variance. Also, the equivalent resistance of the device remains relatively constant over the illustrated current range. Further, the voltage drop across devices 10 even at three Amps for all four parts tested was maintained under 100 millivolts.
Referring now to FIG. 7 an alternative multi layer PTC device 50 is illustrated. Device 50 includes many of the same components discussed above, such as fuse element 24 (and associated pads 22a and 22b and termination areas 26a and 26b). Device 50 also includes a protective coating 32 covering fuse element 24 and a part of the fuse element pads as shown above. In one embodiment, device 50 is configured to mount such that fuse element 24 faces towards the PCB. Alternatively, device 50 could be mounted in the opposite orientation. Device 50 also includes upper and insulating substrate 12 having, e.g., etched electrodes 20a and 16 as described above. Marking text 34 is placed in one embodiment on a top surface of upper insulating substrate 12. Device 50 further includes lower insulating substrate 14 having, e.g., etched upper and lower copper electrodes 18 and 20b. Inner electrodes 16 and 18 as shown above extend at least halfway across their associated substrates 12 and 14 to create a desired opening characteristics for adjacent PTC thermistor layers 30a and 30b (referred to herein collectively as PTC thermistor layers 30 or generally, individually as PTC thermistor layer 30).
Device 50 includes three PTC thermistor layers 30a, 30b and 30c (collectively 30). Device 50 further includes two additional inner insulating substrates 52 and 54 having, e.g., upper and lower electrodes 38, 40, 42 and 44, respectively, which like electrodes 16 and 18 extend the majority of the way across their respective insulated substrate 52, 52, 54, and 54. Each of the electrodes 16, 18, 20a, 30b, 38, 40, 42 and 44 can be etched or formed as otherwise described herein onto a respective FR-4 or polyimide insulating substrate 12. PTC thermistor layers 30 are sandwiched between respective electrode bearing insulating substrates via any of the methods described above. Device 50, like device 10, can be made as an array of devices 50, which are singulated into individual devices.
PTC thermistor layers 30a to 30c each operate the same as PTC thermistor layer 30 of device 10, namely, the layers are conductive under normal operating current loads. Upon an overload condition that opens fuse element 24, PTC thermistor layers 30 heat up causing their temperatures and resistances to rise to a threshold point at which the temperatures and resistances increase exponentially, resulting in a highly resistive electrical path, akin to an open-circuit of fuse element 24. The additional PTC thermistor layers for a given size package increase the rating of the PTC component of device 50. Thus while three PTC thermistor layers 30 are shown with device 50, two layers or four or more layers could be provided as needed to produce a device 50 having a desirable fuse rating. The collective rating of PTC thermistor layers 30 can be the same or slightly different, e.g., lower than that of metallic element 24.
Referring now to FIG. 8, device 110 illustrates an alternative integrated metallic/PTC thermistor device. Here, PTC thermistor layer 130 is ceramic-based as opposed to the polymeric material of the Polyfuse® LF1206L device. One suitable ceramic-based thermistor material is disclosed in U.S. Pat. No. 6,218,928, entitled "PTC Thermistor Material", assigned on its face to TDK Corporation (Tokyo, JP).
Device 110 includes an insulating substrate 112, which can for example be an ceramic material or glass. Upper and lower base electrodes 120a and 120b are formed respectively on upper and lower surfaces of substrate 112 via thick film screen printing or sputtering. Electrodes 120a and 120b can again be formed of one or more metal, such as silver, copper, nickel, tin and alloys thereof applied to the surface of the polyimide in any of the above-mentioned ways.
Base electrode 120b is shaped to form the fuse element. Electrode 120b for example includes pad areas 122a and 122b extending inwardly to element 124 and outwardly to larger termination areas 126a and 126b as shown above with electrode 20, pad areas 22, element 24 and termination areas 26. Termination areas 126a and 126b are eventually plated along with upper copper layer 120a to form terminations 136a and 136b. Metallic fuse element 124 of device 110 can have any of the shapes, dimensions and dissimilar metals discussed above for element 24 of devices 10 and 50.
A ceramic PTC ("CPTC") thermistor layer 130 is located on a first side of insulating base 112, e.g., via thick film screen printing or spin coating. As illustrated, CPTC thermistor layer 130 contacts portions of electrodes 120a. An upper cover layer 132a (e.g., fired glass) is applied to CPTC thermistor layer 130 and exposed portions of electrodes 120a. Although not shown, marking indicia (discussed above) can be provided on the top surface of CPTC thermistor layer 130 and be viewable through upper cover layer 132a.
A lower cover layer 132b (e.g., fired glass) is applied to lower electrode 120b and exposed portions of substrate 112. Terminations 136a and 136b are formed on the side edges of substrate 112, electrodes 120a and 120b and cover layers 132a and 132b. Terminations 136a and 136b also cover portions of the top and bottom surfaces, respectively, of, e.g., glass, cover layers 132a and 132b. Terminations 136a and 136b can include multiple metallizations as discussed and shown above. Further, multiple CPTC thermistor layers 130 can be applied between multiple insulating layers 112 in a manner similar to the polymeric device of FIG. 7.
In operation, current flows from e.g., termination 136a to termination 136b through upper and lower electrodes 120a and 120b and both CPTC thermistor layer 130 and the metallic fuse element in parallel until the fuse element opens. Upon the opening of the fuse element, CPTC thermistor layer 130 becomes highly resistive and limits the current traveling from termination 136a to termination 136b. When the power surge has dissipated, CPTC thermistor layer 130 becomes conducting such that current can travel across device 110.
Referring now to FIG. 9, device 150 illustrates an alternative integrated metallic/CPTC thermistor device. Here again, CPTC thermistor layer 130 is ceramic based as opposed to the polymeric material of the Polyfuse® LF1206L device. In device 150, CPTC thermistor layer 130 doubles as the base substrate, taking advantage of the relatively rigid nature of the ceramic based material.
Upper and lower base electrodes 120a and 120b are formed respectively on upper and lower surfaces of CPTC thermistor layer 130 via thick film screen printing or sputtering. Electrodes 120a and 120b can be of one or more metal, such as silver, copper, nickel, tin and alloys thereof applied to the surface of CPTC thermistor layer 130 in any of the above-mentioned ways.
In device 150, lower base electrode 120b does not form the metallic fuse element but instead acts with CPTC thermistor layer 130, upper base electrode 120a and terminations 136a and 136b to allow current to flow through CPTC thermistor layer 130 under normal operating conditions.
A thin insulating layer 112, e.g., glass, is applied over lower base electrode 120b and any exposed area of the bottom surface of CPTC thermistor layer 130. A third, fuse element electrode 152 is shaped onto substrate 112 to form the fuse element. Electrode 152 can for example include the same pad areas 122a and 122b extending inwardly to element 124 and outwardly to larger termination areas 126a and 126b (shown above in FIG. 8). The metallic fuse element of device 150 can have any of the shapes, dimensions and dissimilar metals discussed above for element 24 of devices 10 and 50 and element 124 of device 8.
An upper cover layer 132a (e.g., glass) is applied to upper base electrode 120a and exposed portions of CPTC thermistor layer 130. Although not shown, marking indicia (discussed above) can be provided on the top surface of upper base electrode 120a and be viewable through upper cover layer 132a.
A lower cover layer 132b (e.g., glass) is applied to fuse element electrode 152 and exposed portions of substrate 112. Terminations 136a and 136b are formed on the side edges of CPTC thermistor layer 130, substrate 112, electrodes 120a, 120b and 152 and cover layers 132a and 132b. Terminations 136a and 136b also cover portions of the top and bottom surfaces, respectively, of, e.g., glass, cover layers 132a and 132b. Terminations 136a and 136b can include multiple metallizations as discussed and shown above.
In device 150 operation, current flows from, e.g., termination 136a to termination 136b through upper electrodes 120a, CPTC thermistor layer 130, electrode 120b and metallic fuse element layer 150 until the fuse element opens. Upon the opening of the fuse element, CPTC thermistor layer 130 becomes non-conducting and prevents current form traveling from termination 136a to termination 136b. When the power surge has dissipated, CPTC thermistor layer 130 becomes conducting, such that current can travel again across device 150.
Referring now to FIG. 10, an alternative CPTC thermistor device 160 is illustrated. CPTC thermistor device 160 advantageously uses both upper and lower base electrodes 120a and 120b to contact both CPTC thermistor layer 130 and fuse element 162, which in the illustrated embodiment is a thick film, thin film or wire bonded fuse element. Fuse element 162, shown as being generally vertically disposed, extends along the edge of the CPTC thermistor layer 130 from one base electrode 120a to the other base electrode 120b. The angle, shape and number of such fuse elements can vary. Base electrodes 120a and 120b are also formed on both sides of CPTC thermistor layer 130 via any suitable technique and from any suitable one or more metal described above.
Device 160 in the illustrated embodiment also includes leads 164 and 166, which can be radially or axially disposed for different mounting arrangements. In device 160 operation, current flows from e.g., upper electrode 120a (lead 164) to lower electrode 120b (lead 166), through CPTC thermistor layer 130 and fuse element 162 in parallel until the fuse element opens. Upon the opening of the fuse element, CPTC thermistor layer 130 becomes non-conducting and prevents current form traveling from upper electrode 120a (lead 164) to lower electrode 120b (lead 166). When the power surge has dissipated, CPTC thermistor layer 130 becomes conducting, such that current can travel again across device 160.
Referring now to FIG. 11, an alternative CPTC thermistor device 170 is illustrated, which is the same as device 160 except that CPTC thermistor layer 130 includes or defines a larger diameter hole or aperture 138 configured to accept a diagonally disposed fuse element 172. Fuse element 172 as shown is soldered or otherwise connected electrically to base electrodes 120a and 120b located on opposite sides of aperture 138. Element 172 is shown extending diagonally across the aperture. The diagonal extension allows element 172 to be lengthened, which can be beneficial for sizing purposes.
CPTC thermistor device 170 also disposes leads 164 and 166 on endplates 174 and 176, respectively, which are in turn soldered to or otherwise connected to base electrodes 120a and 120b, respectively. Endplates 174 and 176 cover aperture 138, protect fuse element 172 and connect the fuse element electrically to leads 164 and 166. Furthermore, the endplates allow the final part to be coated with a protective material, e.g., epoxy, maintaining a void in aperture 138, which improves the fusing performance of fuse element 172. Leads 164 and 166 are shown extending from endplates 174 and 176 in a radial fashion. Alternatively, leads 164 and 166 extend from endplates 174 and 176 in an axial direction, e.g., as shown in FIG. 10.
The wire fuse element CPTC thermistor devices 160 and 170 operate the same as the thin film CPTC thermistor devices 110 and 150, which operate at least substantially the same as the polymer based PTC thermistor devices discussed above. Current under normal operation flows through both CPTC thermistor layer 130 and fuse elements 124, 152, 162 or 172 until an overcurrent event occurs. At such time, the fuse element opens, CPTC thermistor layer 130 becomes non-conducting, such that device 110, 150, 160 or 170 does not allow the overcurrent to pass to electrical components downstream of the device. When the overcurrent event subsides, CPTC thermistor layer 130 resets itself to a conducting state, allowing the protected circuit to function, albeit at a larger voltage drop across device 110, 150, 160 or 170.
FIG. 12 shows a surface mount configuration for either of the devices described in FIG. 10 or 11. Here, the PTC or CPTC device includes end plates 182 and 184, each having a pad area 180 configured to be reflow or wave soldered to a printed circuit board. The illustrated embodiment shows a CPTC disk 130 (fuse element present but not seen), wherein end plates 182 and 184 and pad areas 180 connect the CPTC disk 130 and fuse element electrically to a trace pattern on the printed circuit board.
Referring now to FIG. 13, circuit 60 illustrates one suitable application for device 10, 50, 110, 150, 160, 170 (referred to simply as device 10 hereafter for convenience) namely a telecom protection application. Telecom protection circuit 60 includes a digital transcriber line ("DSL") driver 62, which can be an interface card located between downstream telecom equipment (not shown) and the data lines shown in FIG. 8. The telecom equipment can include equipment for a central office switch, which switches calls from one point to another, e.g., switches digital voice or internet data.
DSL driver 62 conditions the signals and regenerates the signals to a switch or other apparatus of the telecom equipment. DSL driver 62 is a bi-directional transceiver that conditions signals sent in both directions over tip line 64 and ring line 66. Transformer 68 prevents direct current ("DC") residing on either side of the transformer from being propagated to the other side of the transformer. Transformer 68 also cancels any noise or signal crosstalk from adjacent lines that are coupled, and therefore common, to both the tip and ring lines. Transformer 68 accordingly couples differential signals.
Transient voltage suppressor 70 includes an overvoltage protection device, such thyristor. Suppressor 70 can for example use a plurality of diodes positioned with a thyristor to reduce capacitance along any path, e.g., from tip line 64 to ring line 66, tip line 64 to ground 72, and ground 72 to ring line 66. The diodes and thyristor are positioned such that each path has at least three capacitance reductions, providing heavily biased pathways that reduce the capacitance stepwise in series to a very low level that will not attenuate or discourage the data signals.
Integrated fuse element/PTC device 10 are positioned in ring line 64 and tip line 66 to protect against an overcurrent condition due for example to a power-cross situation, in which a phone line or data line becomes inductively coupled to a power line, producing a continuous overvoltage condition. Transient voltage suppressor 70 clamps the overvoltage at a safe level, dissipating a great deal of energy and triggering overcurrent device 10.
If only a metallic element is used, the corresponding fuse in circuit 60 has to be replaced. If only a PTC element is used, the resistance of the PTC element is substantially higher, limiting how far DSL driver 62 can drive the DSL signals down tip 64 or ring 66 lines. Because power-cross line conditions are rare, device 10 provides a resettable device that operates initially at a low resistance. If a power-cross condition does occur, the fuse element opens and the PTC device trips and eventually resets, such that circuit 60 still functions, at least at a limited range of data travel.
Referring now to FIG. 14, circuit 80 illustrates another application for integrated fuse element/PTC device 10, namely, a data bus circuit. The illustrated data bus circuit uses an IEEE 1394 controller 82, which is used with computers and other equipment, such as video cameras and cable boxes. Associated 1394 connector 84 is small, which is advantageous for the above applications. Circuit 80 uses two twisted pair conductors TPA and TPB, which each transmit data bi-directionally between controller 82 and connector 84.
Circuit 80 includes transient voltage suppressors 86 placed across the data lines to ground 88. Voltage suppressors 86 suppress electrostatic discharge ("ESD") events occurring on data lines TPA and TPB. Circuit 80 also includes a varistor 90, which suppresses ESD or other transients occurring on voltage line V.sub.bus 92. V.sub.bus is for example a 33 VDC source that controller 82 uses to drive voltage down line 92 to power whatever is connected to connector 84, e.g., a printer or modem.
Integrated fuse element/PTC device 10 protects associated equipment from any type of overcurrent condition occurring on power line 92. Here again, it is desirable that device 10 have as low a resistance as possible, so that the voltage drop across the device is as low as possible, and so that as much power can be delivered from controller 82 to connector 84 and associated devices as possible. Device 10 is accordingly well-suited for this application because it is unlikely that line 92 will experience an overcurrent condition.
Device 10 can be used equally as effectively in universal serial bus ("USB") data circuits and applications. Further, the devices can be used in a powered Ethernet circuit. In a power over Ethernet circuit, two of the four twisted pairs in a Cat3/5 cable carry power and may also carry data. Power delivery capability for such circuit is limited, making device 10 well suited for such application.
Referring now to FIG. 15, circuit 100 illustrates a further application for integrated fuse element/PTC device 10, namely, a battery protection circuit. Circuit 100 operates with a charger 94 for, e.g., a cellular phone 96. Control circuit 102 of battery pack circuit 100 senses a voltage supplied by charger 94. If, for example, the polarity of the voltage is wrong, or the voltage level is wrong, controller 102 opens redundant field effect transistor ("FET") switches 104 to stop any current from flowing through circuit 100 to battery 108. Control circuit 102 can also monitor temperature to look for thermal runaway. Here too, circuit 102 shuts down the current flow via switches 104 to battery 108.
PTC fuse device 10 provides a layer of redundant circuit protection. For example, if control circuit 102 does not operate properly or FET's 104 become shorted, PTC fuse device 10 provides a backup layer of overcurrent protection. Battery 106 of battery pack 100 varies in DC voltage making the low resistance of device 10 important. For example, if an overcurrent device in a three VDC battery pack drops ¼ VDC, the over-current device consumes eight percent of the life of the battery. Battery 108 can have a drop-out voltage below which the cellular phone does not work, making the above life consumption percentage even higher. Thus a voltage drop in the millivolt range for device 10 in FIG. 6 is well-suited for this application.
It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present subject matter and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.

Integrated thermistor and metallic element device and method


A game net post adapted to be placed in substantially vertical position into the ground or floor, the post being provided with mechanism for attaching a net and for tensioning a net cable, the cross-sectional profile of the post presenting a cavity, open to the outside, and having cross-sectional dimensions such that the net cable tensioning mechanism may be received and substantially housed within it. Preferably, in the cavity, a longitudinal member is slideably inserted and which has affixed to it the net cable tensioning mechanism. The tensioning mechanism may comprise devices carrying a wire shaft and a handle coupled to the wire shaft, adapted to rotate the wire shaft while avoiding the longitudinal displacement thereof, a running nut with a hook device being associated with the wire shaft. A second embodiment is a two-part height-adjustable post. The two post parts have cross-sectional profiles such that the second one is slideable within the first one of such parts, the cross-sectional profile of each of the post parts presents a cavity, open to the outside, and having cross-sectional dimensions such that the net cable tensioning mechanism may be received in it. Also with this embodiment a longitudinal member is preferably inserted which is affixed to one post part and is slideable within the cavity in the other post part, the longitudinal member having affixed to it the net cable tensioning mechanism.

State of the Art
The invention relates to a game net post adapted to be placed in substantially vertical position in the ground or floor, and being provided with means for attaching a net and for tensioning a net cable.
Net posts for games such as volleybal have been known in a great many embodiments. Examples are found in U.S. Pat. No. 5,215,310, granted to Allbright, and U.S. Pat. No. 5,308,085, granted to the present inventor and assigned to the same assignee.
All known game net posts have the means for attaching and tensioning the net cable somehow at the outside of the post proper. This is a hindrance both during storage and set up and during the game because players may be hurt.


A plurality of fuel rods containing fissile material are arranged in triangle lattices. A plurality of water rods groups are arranged among the fuel rods. Each of the water rods groups includes no fuel rod but a plurality of water rods which are arranged adjacently each other in triangle lattices having substantially same pitch as the fuel rods. The water rods groups are arranged not adjacently each other, and are surrounded with the fuel rods. the outer diameter of the water rod is smaller than the pitch. The fuel assembly is able to suppress increment of pressure loss because of formation of coolant path among adjacent water rods. Further, void reactivity coefficient is able to be small.

The present invention relates to a fuel assembly, especially to the fuel assembly preferable for use in boiling water reactors.
In the boiling water reactors, cooling water having moderating function exists in two regions, namely, two phase flow region in the channel box and saturated water region outside of the channel box. In limited space in the reactor core, the optimum value for area ratio of the two regions is different depending on evaluating subjects.
In order to improve fuel economy of the boiling water reactor by achieving high burn up of fuel assemblies, life extension of the fuel assemblies, and uranium saving, there are many methods such as a method of arranging unboiled region, namely, a plurality of water rods, in the fuel assembly, a method of increasing uranium inventory in the fuel assembly, and a method of increasing composing lattice number of fuel rods etc. One of the example of the prior art is the fuel assembly disclosed in JP-A-62-217186 (1987). The fuel assembly has a fuel arrangement of 9 lines by 9 rows, and two water rods having large diameter arranged adjacently in diagonal direction of the fuel rod arrangement. Using the fuel assembly, fuel economy can be improved by increasing of composing lattice number and unboiled region and flattening of power distribution without decreasing the uranium inventory.
And, making void reactivity coefficient close to zero as possible is required for the boiling water reactor in order to improve safety and operability of the reactors.
Void in the boiling water reactor changes depending on power level and coolant flow rate, and causes change of coolant density during reactor operation.
Void reactivity coefficient of the boiling water reactor has a large negative value. The negative void reactivity coefficient has an effect to suppress power increase when reactivity is added. Therefore, if abnormal phenomena which will cause pressure increase in the reactor is generated and such control operation to suppress the pressure increase as control rods insertion is not performed, void in the reactor is decreased, and subsequently rapid power increase is caused by addition of positive reactivity. Consequently, there is a possibility to cause failure of fuel rods by overheating.
Accordingly, lessening of the void reactivity coefficient can moderate the above described abnormal phenomena, and is able to improve safety and operability of the reactor.
As to methods for the lessening of the void reactivity coefficient, a method of increasing water to fuel volume ratio in case of using enriched uranium and plutonium fuel, a method of decreasing water to fuel volume ratio in case of using plutonium fuel, and a method of decreasing void generating area in the case of using enriched uranium and plutonium fuel can be considered.
An example of the methods of increasing water to fuel volume ratio is disclosed in JP-A-63-25592 (1988). The cited reference describes the method in which the cross sectional area of the fuel assembly is increased to almost twice, total cross sectional area of the water rods is increased, and moderator (water) and fuel (uranium) in the fuel assembly are homogenized so as to distribute almost equal quantity of unboiling water to each of fuel rods in order to improve neutron moderating effect and to accelerate effective burning of the uranium by increasing of cross sectional area of the water rods without decreasing the uranium inventory per a fuel assembly.
An example of the methods of decreasing water to fuel volume ratio is disclosed in JP-A-62-259086 (1987). The cited reference describes the method to make the number of M closest integer of 0.87 N when assign N to the number of fuel rods arranged line and M to the number of fuel rods arranged row (both N and m are integers) in a high conversion nuclear reactor loaded with a plurality of fuel assemblies having fuel rods arrangement of triangle lattices. The high conversion nuclear reactor is aimed at positive conversion of uranium-238 to fissile plutonium-239 by decreasing moderating effect on neutron with small water to fuel volume ratio.
In order to decrease the void reactivity coefficient as above described, it is necessary to make remarkable design change to the boiling water reactor such as making the fuel assembly large, or to make the reactor high conversion type etc.


A container holder which may be used to hold or support a beverage container in an automobile by inserting an elongated member with a securing portion between the back rest and seat cushion of a seat, or between the back rests of two adjacent seats. The elongated member with securing portion may be releasably or permanently attached to a receptacle portion used to hold the beverage container. Also, the container holder may have a receptacle portion that can be varied in size to hold different sizes of containers. The container holder can be used on top of a seat cushion or on top of an arm rest.

The present invention relates generally to container holders, and more particularly to a container holder which may be used to hold a beverage container in an automobile by inserting an elongated member of the holder between the back rest and seat cushion of a seat, or between the back rests of two adjacent seats.
Different types of holders have been designed for the purpose of holding a beverage container in an automobile. For example, U.S. Pat. No. 2,640,595, issued to Byford on Jun. 2, 1953, discloses an article holder. The holder has a flap 7 that may be inserted between the back rest and seat cushion of an automobile seat. However, the holder is made out of a stiff material such as plastic or sheet metal, which makes it difficult to carry the holder, for example, in luggage. Also, the carrying receptacles of the holder are relatively short. As a result, cans or bottles inserted into the receptacles may fly out of the receptacles when an automobile is brought to a quick stop.
U.S. Pat. No. 4,678,154, issued to McFarland on Jul. 7, 1987, discloses another beverage container holder. As shown in FIG. 5 of this patent, the holder is held in place by arm 18 inserted between a back rest and seat cushion of a seat. However, arm 18 will not prevent the holder from moving forward when a motor vehicle stops quickly. As such, beverage may spill from a container inserted into the holder.


It is desirable that data stored in an old storage device is migrated to a new storage device without any interruption. According to a computer system of this invention, in a first data storage device, a second data storage area of a second data storage device is recognized as a virtualized data storage area of the first data storage device, a data copy relation between the first data storage area and the virtualized data storage area is established, the second data storage area is recognized from the computer based on the data copy relation, data is copied from the first data storage area to the virtualized data storage area based on the data copy relation, and after completion of a data copy operation, a connecting path is switched from the first data storage area to the second data storage area based on the data copy relation.

This invention relates to a computer system including a plurality of data storage systems and computers, and more particularly to data migration in a virtualized environment, where a data storage system is virtualized.
Computers store data in the data storage system. When a retention period of the data is longer than the life of the data storage system, it is required to migrate the data stored in an old data storage system to a new storage system before the device reaches its life. Upon the data migration, it is desirable that an unavailable time period be as short as possible, in which the computer cannot use the storage system, and furthermore, migration be conducted without any interruption.
As for a technique to migrate data from an old data storage system to a new one, for example, JP 10-508967 A and JP 2004-220450 A are disclosed. According to JP 10-508967 A and JP 2004-220450 A, before the start of data migration from an old data storage system to a new one, the computer is once disconnected and reconnected to a new data storage system.
Moreover, according to JP 2004-220450 A, in the new data storage system, a virtualized device (data storage area) corresponding to the device in the old data storage system is provided. By accessing to the virtualized device, the computer can access the device in the old data storage system corresponding to the virtualized device.


A stabilizer for glassware in an automatic dishwasher has an inside to contact the item of glassware and an outside opposite the inside. A resilient mesh is selectably mountable on an item of glassware to at least partially encircle an outer circumference of the item of glassware to removably retain the item of glassware in the automatic dishwasher. The mesh includes a longitudinal axis defined by the mesh, and channels open on the inside to channel water from between the stabilizer and the item of glassware under an influence of gravity to prevent an accumulation of water in the stabilizer or between the stabilizer and the item of glassware. At least one permanent magnet is affixed to the resilient mesh to selectively magnetically attach the stabilizer and the item of glassware to an adjacent magnetically responsive object disposed in the dishwasher to thereby stabilize the item of glassware in the dishwasher and to cushion the item of glassware from impact.

Some fine glassware, for example lead crystal beverage containers and relatively high value glassware are advertised as dishwasher safe when a "china" setting is selected on the dishwasher controls. The china setting may reduce the maximum temperature and decrease water jet pressure. In some instances, even though the china setting has been selected, fine glassware may become chipped or broken during operation of the automatic dishwasher. The damage to the fine glassware may occur because the jets of water in the dishwasher cause the glassware to move, flip, and impact adjacent items of glassware. Relative motion between adjacent items of glassware may also cause worn spots, or etching at the area of contact. This will have an appearance of a cloudy ring or spot on the item of glassware.

Stabilizer for glassware for use in automatic dishwasher


A work vehicle including a transmission that transmits power of an engine to wheels at a plurality of different transmission gear ratios, the work vehicle traveling while maintaining a targeted speed by controlling a degree of opening of an accelerator, brakes, and the transmission, wherein the work vehicle includes a controller which inhibits change in the transmission gear ratio of the transmission when the transmission shifts up before lapse of a first predetermined time after the transmission shifts down while the vehicle is running downhill and then before a second predetermined time elapses, the transmission shifts down while the vehicle is running downhill.

Work vehicles, such as hydraulic shovels and dump trucks, include those having a multistage transmission having a plurality of transmission gear ratios capable of changing to a different transmission gear ratio, and in which power of an engine is transmitted to wheels. There is a technology (for example, Patent Literature 1) in which, while a work vehicle provided with a multistage transmission is traveling, after an upshift is performed, when a downshift is performed with a predetermined time, the transmission is inhibited from changing transmission gears.

Work vehicle and method of controlling the same


An electrophoretic system having a plurality of separation lanes is provided with an automatic calibration feature in which each lane is separately calibrated. For each lane, the calibration coefficients map a spectrum of received channel intensities onto values reflective of the relative likelihood of each of a plurality of dyes being present. Individual peaks, reflective of the influence of a single dye, are isolated from among the various sets of detected light intensity spectra, and these can be used to both detect the number of dye components present, and also to establish exemplary vectors for the calibration coefficients which may then be clustered and further processed to arrive at a calibration matrix for the system. The system of the present invention thus permits one to use different dye sets to tag DNA nucleotides in samples which migrate in separate lanes, and also allows for in-situ calibration with new, previously unused dye sets.

In the detector system in accordance with U.S. Pat. No. 6,027,627, fluoresced light from migrating species within a plurality of capillaries aligned in parallel passes through a filter, a transmission grating beam splitter and a lens before it impinges on a CCD detector array. In the preferred embodiment, the CCD detector array comprises 1024×256 pixels. The first dimension, (1024 pixels) covers 96 parallel capillaries, each capillary being focused onto at least one of the 1024 rows, although the number of rows per capillary can be increased by selecting a lens with a different focal length or changing other optical parameters. The second dimension (256 pixels) covers the fluorescence spectrum spread by the transmission grating.
In this prior art system, both the first order and second order components can be focused onto the detector array, although this is not an absolute requirement. What is required, however, is that a spectrum (such as represented by the 1st order components) be created for each capillary and detected. The spectrum of interest should include the wavelengths of light at which the dyes are known to fluoresce. The spectrum of interest for each capillary is spread over P contiguous pixels and these are divided into R channels of Q contiguous pixels, R=P/Q. R should be at least as large as the number of dyes M being used and preferably is greater than this number.
The detector of the prior art system outputs a spectrum comprising R light intensity values for each capillary, each time that data is provided to the associated processor. The processor then maps the spectrum of R intensity values for each capillary, onto values which help determine which dye has been detected in that capillary. This is typically done by multiplying calibration coefficients by the vector of intensity values, for each capillary.
The principle behind the calibration coefficients is that a spectrum of received light intensities in each of the channels is caused by the spectrum of a single dye (tagging a corresponding base) weighted by the effects (calibration coefficients) of the detection system. If I0(n), I1(n), . . . , I9(n) represent the measured intensities of the R=10 channels at the nth set of outputs from the CCD (after preprocessing including detection, binning and baseline subtraction), B0(n), B1(n), . . . , B3(n) is a vector representing the contribution (presence 1 or absence 0) from of the M=4 bases, and Cij are coefficients of a known 10×4 matrix which maps the bases onto the detected channels, we then having the following relationship:
                              (                                                                                I                    0                                                                          (                    n                    )                                                                                I                    1                                                                          (                    n                    )                                                                                I                    2                                                                          (                    n                    )                                                                                …                                                                    …                                                                                I                    9                                                                          (                    n                    )                                                                                )                =                              (                                                                                C                    00                                                                                C                    01                                                                                C                    02                                                                                C                    03                                                                                C                    10                                                                                C                    11                                                                                C                    12                                                                                C                    13                                                                                C                    20                                                                                C                    21                                                                                C                    22                                                                                C                    23                                                                                …                                                  …                                                  …                                                  …                                                                              …                                                  …                                                  …                                                  …                                                                                C                    90                                                                                C                    91                                                                                C                    92                                                                                C                    93                                                                        )                                          (                                                            B                  0                                                                  (                  n                  )                                                                                B                  1                                                                  (                  n                  )                                                                                B                  2                                                                  (                  n                  )                                                                                B                  3                                                                  (                  n                  )                                                      )                                              (                  Eq          .                                                    1                )
Eq. 1 can thus be rewritten as:I(n)=C B(n)  (Eq. 2)
Given a vector of intensities output by a CCD for each separation lane, the theory of determining the presence or absence of each of the M=4 bases from the R=10 wavelength channels is fairly well established. This is simply a particular case of an over-determined system in which a smaller number of unknowns is determined from a greater number of equations. After mathematical transformation, Eq. 2 can be written as:B(n)=(CTC)−1CTI(n)  (Eq. 3)where B0(n), . . . , B3(n) now represent the unknown values of the individual bases as functions of time index n, each value being reflective of the relative likelihood of the corresponding dye tagging that base being present; I0(n), I1(n), . . . I9(n) are the fluorescence intensities of the ten channels, and Cij's are the coefficients of wavelength i under known base j and where CT is a transpose of the matrix C and A=(CT C)−1 CT is the pseudo-inverse of matrix C. While in the above analysis, C is a 10×4 matrix because a total of ten channels and four bases are used, in the general case, C is an R×M matrix wherein R≧M, and R and M are both integers greater than 2.
Typically, in prior art systems, the calibration matrix C is determined at the time the system is created. More particularly, calibration matrix C is specific to a set of dyes that are used, and is constant for all separation lanes in a system. If such a prior art system is then modified, such as by upgrading to a new set of optical filters, the calibration matrix C needs to be re-calibrated.
FIG. 1 illustrates two shortcomings of using a constant calibration matrix for all capillaries in a capillary array. As seen in FIG. 1, the 0th order spectral intensities 102 from each of the capillaries do not map onto the same pixel in corresponding pixel columns. In particular, the 0th order spectral intensities from capillaries 7 and 10, which are detected in their corresponding pixel columns 104, 106, respectively, do not fall on the same-positioned pixel as do the 0th order spectral images from the remaining capillaries. Similarly, the 1st order spectral intensities 112 from capillaries 7 and 10 in these same columns also do not fall on the same-positioned pixels as do the 1st order spectral images from the remaining capillaries, but rather are offset by a skew of a single pixel. A consequence of this skewness, which may be caused by improper arrangement of capillaries 7 and 10 within the capillary array, is that the binning process for 1st order intensities from capillaries 7 and 10 results in a spectrum which would be slightly different than if the binning process started one pixel over. As a result, using a single calibration matrix C for all the capillaries, leads to imprecise results, when Eq. 3 is invoked to try to identify the due causes the detected fluorescence from capillaries 7 and 10. As also illustrated in FIG. 1, the 1st order spectral image 114 for capillary 1 maps onto one more pixel than do the spectral images of the remaining capillaries. This feature, which may be caused by such factors as coma, spherical aberrations, astigma, and lateral chromatic aberration of the grating image system, also may lead to imprecisions when binning followed by use of the calibration matrix as in Eq. 3.
In general, different dye sets have different spectra. As a consequence, each dye set has a different calibration matrix. Consequently, a further disadvantage of using a single calibration matrix for a multi-lane separation system, is that one cannot run multiple dye sets in different separation lanes.

Electrophoretic analysis system having in-situ calibration


A digital pen-based application form filling system with a modification prevention function, which eliminates a possibility that digital information initially written in digital paper using a digital pen may be modified deliberately or accidentally. The system prints a new fine pattern over areas in already written digital paper whose contents one wishes to protect against being modified. This printing adds a fine pattern to an original dot pattern already present on the digital paper to make it theoretically impossible to enter information into these areas using the digital pen.

The present invention relates to an application form filling system using a digital pen with a content modification prevention function.
In recent years, a growing number of governments, municipal offices and corporations are transforming written applications and circulars into digital documents to facilitate document management and inquiries. One example of a technology for real-time transforming of information hand-written on an application form into digital data is WO01/48590A1 that describes a digital pen and digital paper.
The digital paper is paper having its surface formed with a special printed dot pattern and printed with a particular document format (FIG. 8). The paper surface is sectioned with virtual lattices of a predetermined size and is assigned a part of a dot pattern formed over a vast area, with dots 82 that are allocated to intersections 81 between virtual lattice lines, and shifted uniquely by a predetermined distance from their associated intersections so that any position on the paper can be identified and located uniquely. A plurality of these dots, for example 6×6 dots, are checked and a unique combination of up, down, left and right deviation values for these 36 dots provides information on an absolute position in the vast planar area. The digital pen comprises a pen that fixes ink on paper to make written characters visible, a camera for reading a dot pattern on the paper surface, a pressure sensor for detecting a writing pressure acting on the pen, an image processor that processes data obtained from the camera and the pressure sensor to generate position information made up of coordinate data on loci of characters-strokes, a memory for temporary storage of the position information, and a wireless transmission device for sending the position information to other devices.
When a user (user) fills in necessary fields in an application from of digital paper using a digital pen, position information is detected based on the dot pattern read by the camera in real time and the pressure sensor detects writing pressure. The position information is stored in memory and transmitted from the wireless transmission device after the completion of form filling. The data received is processed by an analyzer that relates the position information to a document format. Then, after undergoing a character recognition process as necessary, the data becomes an electronic document. Then, in general tasks a plurality of persons in charge successively adds information to the digital paper, such as examiner's sign, approval signature and comments, in a procedure similar to the above by using the digital pen.

Application system with function for preventing modification


A surgical cast venting device comprises two elongate strips or two layers of flexible material, at least one of which is porous. The strips or layers are spaced apart from each other and extend parallel to each other. Flexible, solid spacer members are arranged between the two strips or layers and connect them together. These members form air passageways between adjacent spacers so that air is normally free to pass along the passageways. A moisture-absorbent fabric layer extends along an outer side of the porous strip or layer opposite the spacers. In an alternate version, there is a first strip which is porous and a series of substantially flat, flexible outer members arranged in a row from one end of the strip to an opposite end. The outer members are spaced from the strip and opposite side edges of the strip and of the outer members are aligned with one another.

This invention relates to venting devices for surgical casts and medical devices such as braces and splints and, in particular, to devices for circulating air under a rigid cast, brace, or splint that may be applied, for example, to permit healing of a broken bone.
A variety of devices for venting surgical casts have been proposed in the past but generally speaking these devices have not met with commercial success to date. Generally, these devices may have tubes which form air passageways to permit air circulation between the rigid cast exterior and the patient's skin. One such venting device is taught in recent U.S. Pat. No. 4,898,160 which issued Feb. 6, 1990 to Alliance Group Inc. This device includes a multiple channeled, flexible form that is placed adjacent to the skin and that is able to adapt to the contour of the body part. The sloping walls of the channels can be formed with a plurality of spaced-apart apertures. Extending upwardly from an upper layer of this device are a number of tubular vents which can extend through the conventional cast material. An air supply line can be connected to the vent opening so as to allow air under pressure to flow into the air passageways. This known venting device can be placed initially over a cast stockingette which is normally first placed on the body part.
In applicant's own U.S. patent application Ser. No. 09/533,214 filed Mar. 23, 2000, there are described a number of different versions of devices for venting surgical casts. In one preferred embodiment, the venting device includes an elongate porous woven fabric strip to which are attached a plurality of flexible, elongate tubes with holes distributed along their respective lengths. The tubes are distributed along the length of the fabric strip and on one side thereof. The elongate strip is suitable for winding around part of a human's body or an animal's body prior to application of a surgical cast. Preferably, the fabric strip comprises a cotton gauze material. Instead of tubes for aerating devices, the aerating devices can take a variety of other forms including flexible layers of interconnected non-woven plastic threads which form numerous, small air passageways, a plurality of spiral-shaped resilient plastic members distributed over the fabric strip, and a plurality of corrugated plastic members, each of which is perforated with numerous small holes.
Experiments conducted by the applicant on various forms of venting devices have shown that key factors in their potential success include their ease of use by medical practitioners, including doctors and nurses, and the amount of comfort that is provided by the venting device after it has been applied and is in position below a rigid cast. Tests conducted by the applicant have shown that it is highly desirable that the venting device be constructed in a way which will apply an even amount of pressure on the skin of the user and in a way which will not cause pinching of the user's skin if the venting device is properly applied. Other significant factors include the ability of the venting device to fit closely on the limb to which it is being applied and in a manner which will not create pressure points on the skin and other regions of discomfort.
Accordingly, it is an object of the present invention to provide an improved venting device which will not cause undue comfort to the wearer or patient when used under a rigid cast, brace, or similar orthopedic device and which can be made at a reasonable cost.
It is a further object of the present invention to provide an improved venting device for a cast, brace, or similar orthopedic device, this venting device including at least one elongate strip of flexible material that is porous to allow passage of air to the skin of the user and also flexible spacer members that are connected to the at least one strip and that form air passageways between the spacer members whereby air can normally pass along these passageways so as to permit air circulation substantially across the length and width of the venting device.

Venting devices for surgical casts and other orthopedic devices


A method for adjusting a tilt angle of a light beam emitted by an optical pickup unit of an optical disc drive, the method includes steps of adjusting the tilt angle of the light beam according to test parameters preinstalled in the optical disc drive; detecting focusing error signals, the focusing error signals being generated based on the light beam reflected from an optical disc; generating current parameters based on the focusing error signals; storing the current parameters; adjusting the tilt angle of the light beam according to the current parameters.

1. Field of the Invention
This invention relates to optical disc drives, and more particularly to a system and a method for adjusting a tilt angle of a light beam related to an optical disc.
2. Description of Related Art
Nowadays, optical discs are widely used for storing information. Related optical disc drives for reproducing/recording data from/onto the optical discs are also widely used.
Referring to FIG. 5, a traditional optical disc drive 500 capable of reproducing/recording an optical disc 600 is illustrated. The optical disc drive 500 includes a spindle motor 502, an optical pickup unit 504, a sled shaft 506, a sled motor 508, and a controller 510. The optical disc 600 is arranged on and rotated at a predetermined velocity by the spindle motor 502. The optical pickup unit 504 is disposed to face a read-out surface of the optical disc 600. The optical pickup unit 504 is movable along a radial direction of the optical disc 600 by the sled motor 508 and the sled shaft 506.
Generally, a light beam emitted by the optical pickup unit 504 is required to be correctly focused onto tracks of the optical disc 600. The tracks are arranged in concentric or spiral manner from an inner side to an outer side of the optical disc 600. During a reproducing or recording process, the optical pickup unit 504 is moved from the inner side to the outer side by the sled motor 508 and the sled shaft 506. However, mechanical parts usually lead to assembling errors, such as the sled shaft 506 assembled in the optical disc drive 500 is usually not absolutely parallel to the optical disc 600. This will cause an oblique angle between a moving path of the optical pickup unit 504 and the optical disc 600. Therefore, a tilt angle of the light beam is required to be adjusted to compensate the oblique angle. A plurality of test parameters are assigned to adjust the tilt angle of the light beam. Generally, the test parameters are derived by testing the disk drive with an ideal glass plate. The test parameters are stored in storage units of the optical disc drive 500, for example, a read only memory (ROM). When the optical disc 600 is loaded in the optical disc drive 500, the test parameters are used to adjust the tilt angle of the light beam so as to correctly focus the light beam onto the tracks.
However, there are many types of optical discs in the market, while a plenty of which are not standard as the ideal glass plate, such as planeness of the optical discs. Especially, recording layers of the optical discs may be warped due to poor quality or improper storage of the optical discs. In this situation, if the light beam is maintained at a same tilt angle during a recording or a reproducing process, the optical discs may be recorded or reproduced incorrectly.
Therefore, an optical disc drive with adjustable tilt angle of the light beam according to the optical discs is desired.

System and method for adjusting tilt angle of light beam


A photographic element according to the invention includes a reflective support, one or more photosensitive silver halide emulsion layers, and a colored antihalation layer interposed between the support and the photosensitive layers. The antihalation layer comprises thin grains of silver in the form of-platelets having a thickness of up to about 20 nm. The platelets are distributed in a suitable matrix or colloidal medium such as gelatin. The thinness of the platelets allows the antihalation layer to be formed effectively at lower silver levels.

Halation has been a persistent problem with photographic films formed by depositing one or more layers of a photosensitive silver halide emulsion onto a support such as a plastic film. The emulsion diffusely transmits light. Such light reaches the support and is reflected back into the emulsion. The silver halide emulsion is thereby reexposed at a location different from the original one. The result is a halo surrounding an image of a bright object on the film.
Three methods have been proposed for preventing such halation. One such method calls for dyeing the support, another for providing a dyed or pigmented layer behind the clear support as an antihalation backing. A third method involves providing a silver antihalation layer between the support and the photosensitive layer(s). Gray silver has been used for this purpose; see James, The Theory of the Photographic Process, 4th Ed., p. 579. The process of making a grey antihalation layer involves precipitation of silver chloride and the addition of a fogging developer to produce filamentary silver similar to the morphology customarily encountered when conventional silver halide films are processed in a B/W developer.
Halation reduces the sharpness of the resulting image. Efforts to minimize the effects of halation have included incorporation of silver or silver halide in the support to lower reflection density. See U.K. Patent No. 1,126,797. Schadt U.S. Pat. No. 4,460,679, issued Jul. 17, 1984, approaches the problem by adding a nonphotosensitive layer containing a chemically bleachable, high strength tinctorial colorant, such as blue colloidal silver, over the support which permits sensitometric control over low coating weight silver halide elements. Ohbayashi U.S. Pat. No. 4,563,406, issued Jan. 7, 1986, places a yellow, blue or gray colorant layer, a white pigment layer and a silver halide emulsion layer over the support to achieve the combined effect of increased sharpness without loss of sensitivity.
Pechmann U.S. Pat. No. 2,921,914, issued Jan. 19, 1966, uses a blue colloidal silver dispersion to absorb longer wavelengths of light for halation control. Preparation of this dispersion involves spontaneous nucleation to derive centers for silver formation, and reduction of the silver salt by tannic acid in the presence of a water soluble strontium salt. This technique has hue control problems related to large nuclei, turbidity and difficulties with bleaching. Severe gel slugging (forming hardened globs), a major concern in antihalation silver preparation, is aggravated by the use of tannic acid. Posse U.S. Pat. No. 3,333,960 issued Aug. 1, 1967, discloses mixing of the Pechmann blue silver with yellow Carey-Lea silver to obtain a neutral coloration which controls halation. Neither approach is completely effective, particularly at low coverage levels. Blue colloidal silver materials made by development of fine silver nuclei have been proposed for use in halide-ion sensitive imaging systems and thermal imaging systems. See Defensive Publication T 900,010 and copending U.S. patent application Ser. No. 07/344,950, filed Apr. 28, 1989, the entire content of which is incorporated by reference herein. The present invention advantageously applies such materials to form antihalation layers displaying improved performance.

Photographic element having improved antihalation layer


Methods for treating vascular conditions associated with localized imbalance in vascular tone, which are hypothesized to be largely due to elevated endothelin (ET) are provided. The methods involve administration of nitric oxide (NO), agents which are able to provide NO, such as NO donors, agents which activate guanyl cyclase, such as YC-1, or agents which prolong the actions of endogenous NO or cyclic guanosine monophosphate (cGMP; a 2nd messenger molecule), such as phosphodiesterase (PDE) inhibitors. According to the invention, such agents are administered in minimal doses or microdoses by any route known in the art, so as to provide dosages which are about one half to about one twentieth (½ to 1/20) of those known to induce vasodilation in “normal” circulations. The low doses of these agents effectively alleviate vascular conditions associated with a reduction in NO production or an attenuation of NO effect, by restoring balance in vascular tone while exerting almost no systemic effect in normal vasculature.

It is widely known that administration of nitric oxide (NO), or compounds which deliver NO (i.e., NO donors, NO producing agents) to a subject, can provoke powerful vasodilator responses. Such administration is often accompanied by a number of undesirable side effects which include headache, flushing, and hypotension.
The physiological role of NO has been described as that of a powerful chronic vasodilator agent based on there being a marked increase in vascular tone following NO synthase (NOS) blockade (Johnson et al., Am. J. Hypertens. 5:919, 1992; Tolins et al., Hypertens. 17:909, 1991). The role of NO as a chronic vasodilator has only been inferred by indirect means, i.e., by removal of NOS activity. Endogenously, much more multiplicity and overlap in the control of vasodilation can be inferred from the scientific literature. For example, vasodilation can be induced by acetylcholine, bradykinin, adenosine, adenosine triphosphate (ATP), histamine, vasoactive intestinal polypeptide (VIP), and leukotrienes, amongst others. The actions of these endogenous modulators have been shown to be dependent, at least in part, on the presence of the endothelium, an effect likely mediated by endothelial derived relaxing factor/NO (EDRF/NO) (Garg, U. C. et al., J. Biol. Chem. 266:9, 1991; Garg, U. C. et al., J. Clin. Invest. 83:1774, 1989; Palmer, R. M. J. et al., Nature 327:524, 1987). Other vasodilator mechanisms exist which are not endothelium dependent, such as β2-adrenergic receptor activation, atrial natriuretic peptide (ANP) and certain prostaglandins. The actions of NO have been suggested to be mostly cGMP-mediated via guanylate cyclase activation, although other mechanisms have been suggested. For example, Garg et al. (J. Biol. Chem. 266:9, 1991; J. Clin. Invest. 83:1774, 1989) and others (Assender, J. W. et al., J. Cardiovasc. Pharmacol. 17(Suppl. 3):S104, 1991; O'Conner, K. J. et al., J. Cardiovasc. Pharmacol. 17(Suppl. 3):S100-103, 1991) demonstrated a difference in the effects of NO-generating vasodilator agents in inhibiting vascular smooth muscle cell growth in culture; however, it is clear that NO can act not only as a vasodilator but also to inhibit vascular growth responses in a number of conditions (Farhy, R. D. et al., Circ. Res. 72:1202, 1993).
It has been believed and widely practised that NO, in humans and animals, produced via sodium nitroprusside (SNP) infusion, causes vasodilation in peripheral vasculature at doses greater than 10 μg/kg per min. It has recently been determined that NO also performs a function through interaction with endothelin (ET) (Banting et al., J. Hypertens. 14:975, 1996; Richard et al., Circulation 91:771, 1995). Prior to this time, ET had been believed to play a minimal role in maintaining tone in the peripheral microvasculature and to have little impact on the state of contraction of smooth muscle in those vessels. Recent studies have indicated (Banting et al., J. Hypertens. 14:975, 1996) that ET is under the inhibitory control of NO and that administration of NOS inhibitors results in elevated levels of ET.
Endothelins were first described in 1988 and have been shown to be powerful vasoconstrictors, predominantly found in vascular endothelium and, since that time, numerous ET antagonists and their pharmaceutically acceptable salts have been identified and can be obtained commercially (e.g., Sigma, American Peptides). Detailed descriptions of the chemical structures of various ET antagonists may be found in U.S. Pat. No. 5,284,828 issued 8 Feb. 1994 to Hemmi et al., U.S. Pat. No. 5,378,715 issued 3 Jan. 1995 to Stein et al., and U.S. Pat. No. 5,382,569 issued 17 Jan. 1995 to Cody et al. In addition, U.S. Pat. No. 5,338,726 issued 16 Aug. 1994 to Shinosaki et al. describes the chemical structure of ET converting enzyme inhibitors. To date, however, antagonists of ET have not been approved for therapeutic use, although a number of investigators have postulated that ET antagonists could be used for conditions ranging from renal failure, endotoxic shock, asthma, angina, or diabetes to pulmonary hypertension and possibly other indications.
Under normal physiological conditions, ET can be found in almost all parts of circulation at very low levels. In general, in the normal rodent circulation ET is not found in elevated quantities and appears to have little detectable role in the normal regulation of vascular tone, i.e., there is no appreciable decrease in blood pressure when an ET antagonist is administered by injection in normal circulation. Further, at present there does not appear to be any evidence suggesting that ET plays a physiological role even in a small portion of the circulation under normal circulatory conditions in experimental models. However, it is likely that the systemic circulation may appear to be normal when, in fact, specific regions of the circulation are undergoing pathophysiological changes such as occurs in conditions such as erectile dysfunction (ED) (Adams et al., Int. J. Impot. Res. 9:85-91, 1997).
Consequently, there are cardiovascular conditions which are traditionally treated in human beings by significant doses of NO or NO donors, such as glyceryl trinitrate (GTN) (0.2 mg/h and greater). However, these doses are known to induce systemic vasodilation and provoke considerable overall systemic side effects (The, L. S. et al., Brit. J. Rheum. 34:636, 1995). This is particularly so where a pathological condition exists only in certain major organs (e.g., heart, kidney, liver). As a result, a satisfactory method for promoting recovery of normal perfusion pressure in organs with certain pathologies without producing overall systemic hypotension has not been discovered.
Based on the understanding that a significant portion of underlying problems in clinical erectile dysfunction relates to "vascular" mechanisms, much of the current state-of-the-art research involves determining the contribution that the different vascular effector control systems make in normal and pathophysiological states. There is substantial understanding of hemodynamic events that lead to an erection, and yet the quantitative roles of each of the neuroeffector, humoral and local systems in these events remain poorly described. Since 1990, NO has been considered the primary non-adrenergic non-cholinergic neurotransmitter in the penis and has been presumed to be the primary mediator of corporal relaxation during erection (Ignarro L. J. et al., Biochem. Biophys. Res. Comm., 170:843, 1990).
It is well established that, for an erection to occur, neurally mediated (autonomic) vasodilation of the penile arterial blood vessel and the trabecular meshwork takes place (Lue, T. F. et al., J. Urol. 137(5):829, 1987) permitting increased blood flow into the cavernous bodies of the penis. The expanding intra corporal volume compresses the effluent veins that lie between the erectile tissue and the surrounding fibrous, relatively inelastic, tunica albuginea. The outflow capacity is thereby decreased and entrapment of blood ensues, resulting in the transformation of the flaccid penis into its erect state (Lue, T. F. et al., J. Urol. 137(5):829, 1987; Juenemann, K. P. et al, J. Urol. 136(1):158, 1986; Lue, T. F. et al., J. Urol. 130:1237, 1983; Weiss, H. et al., Ann Intern. Med. 76:793, 1980). The level of arterial vascular tone (i.e., blood pressure) is one of critical importance in this process, although adequate perfusion pressure is also a necessary factor. The converse, detumescence, is mediated by the sympathetic nervous system (Saenz de Tajada, I. et al., Am. J. Physiol. 254:H459, 1988; Juenemann, K. P. et al., Br. J. Urol. 64, 1989).
The issue of "impotence" (defined as "a pattern of persistent or recurrent inability to develop or maintain an erection of sufficient rigidity for successful coitus") was discussed at a consensus conference of the National Institutes of Health (NIH) in Washington in December 1992 and has been clearly identified as having a wide range of causative or associated factors. The Massachusetts Male Aging Study (MMAS) has provided an updated view of the epidemiology of erectile dysfunction. It is accepted that the prevalence of impotence increases with age (Kinsey A. C. et al., "Sexual Behaviour in the Human Male", W.B. Saunders: Philadelphia, 1948). Severe or complete ED increases from 5 to 15% between 40 and 70 years of age, (Feldman, H. A. et al., J. Urol. 151:54, 1994). ED has been shown to be "directly correlated with heart disease, hypertension, diabetes, associated medications, indices of anger and depression, and inversely with serum dehydroepiandrosterone, high density lipoprotein, cholesterol and an index of dominant personality."
It is now estimated that in North America there are more than 30,000,000 men with some form of ED, a significant increase from the figure of 10,000,000 quoted just 10 years ago (Shabsigh, R. et al., Urology 32:83, 1988; Whitehead E., Geriatrics 43(2):114, 1988; Furlow, W. L. et al., Med. Aspects Human Sexuality 19:13, 1985). From these figures it is also reasonable to estimate that as many as three million Canadian men may have a degree of ED. The direct cost of treating impotence is significant. Reliable figures from 1985 show that the cost of treating impotence exceeded 146 million dollars in the United States in that year alone (National Center for Health Statistics) and this number is just the estimated market size for one type of injectable therapy. The secondary effects and indirect costs associated with ED suggest that impotence and sexual dysfunction are medical icebergs. The consequences of sexual dysfunction may be seen in strains on the host relationship potentially leading to marital breakdown, violence, work related sequelae, deviant sexual behaviour and impacts on children, when present, that can carry the damage into a new generation of unwanted behaviours. If ED underlies even a small but significant percentage of marital and family breakdown, then it adds vastly to the social and economic burden in society. The pragmatic issue is that large numbers of men are now being treated for ED and most of the treatments are fairly blunt instruments (e.g., intracavernosal injection (ICI)) of mixed vasoactive compounds, penile prosthesis insertion) with significant cost and complications (ICI: pain, priapism, dislike of the technique; prostheses: reoperation, infection, distortion of body image).
Administration of NO, or compounds which are able to deliver NO, have been suggested as possible therapies; however, these agents can provoke powerful yet inappropriate vasodilator responses (Brock et al., J. Urol. 150:864, 1993). Such administration is often accompanied by a number of undesirable side effects related to systemic vasodilation which include headache, flushing, and hypotension. Consequently, there is a real need to provide methods whereby ED and other vascular disease may be quickly and effectively treated without any inappropriate side effects.

This patent is subject to a terminal disclaimer.


A two-stroke engine (1, 31, 41, 51) includes a cylinder (2) having a combustion chamber (5). The combustion chamber (5) is delimited by a piston (7) which drives a crankshaft (25) rotatably journalled in a crankcase (3). The two-stroke engine (1, 31, 41, 51) includes a fuel line (14) wherein an electromagnetic valve (18) is mounted. The valve (18) is controlled by a control unit. An air channel (27) is provided for supplying combustion air. The two-stroke engine (1, 31, 41, 51) has at least one transfer channel (12) which connects the combustion chamber (5) to the crankcase (3) at pregiven piston positions. An ignition module (20, 30) is provided which triggers the ignition of a spark plug (8) projecting into the combustion chamber (5). The valve (18) and the control of the valve (18) are integrated into the ignition module (20, 30).

A two-stroke engine is known from U.S. Pat. No. 6,851,402 to which fuel is supplied via an electronically controlled injection valve. The injection valve opens with an injection nozzle into the transfer channel. The injection takes place in dependence upon the engine speed (rpm) at pregiven positions of the piston. Accordingly, the control of the injection valve is connected to a unit which determines the rpm of the crankshaft.