A programmable storage element for redundancy-programing includes a programmable antifuse circuit, which includes a plurality of first resistors and a switching circuit for coupling the first resistors in series in response to a plurality of first control signals and for coupling the first resistors in parallel in response to a plurality of second control signals to permit programing of the first resistors, and a sensing circuit for determining whether or not the first resistors have been programmed. The state of the first resistors is determined by comparing a first voltage drop across the first resistors with a second voltage drop across a second resistor. Each of the first resistors is an unsilicided polysilicon conductor which has an irreversible resistance decrease when a predetermined threshold current is applied for a minimum period of time.

The capability for redundancy-programing after fabricating integrated semiconductor devices is desirable for many devices including programmable logic devices, programmable memories and linear circuits, as well as for selecting discretionary wiring in VLSI devices.
In a random access memory (RAM) device, for example, a large number of memory cells are arranged in rows and columns. The density of defects generated in the RAM during manufacturing is relatively independent of the integration density of the device, depending more on the semiconductor manufacturing technology. In-general, the higher the integration density of the device, the larger the ratio of normal memory cells to defective memory cells. This larger ratio is one of the advantages of increasing the integration of a semiconductor memory device.
Even if the RAM includes only one defective memory cell, the device cannot be operated normally. To overcome this problem, RAM devices may include a plurality of redundant memory cells, e.g., redundant rows and/or columns of memory cells. Thus, when a defective memory cell is detected by testing, for example, during the final stages of the manufacturing process, it is replaced by one or more redundant memory cells. This replacement is generally accomplished by replacing a row or column of memory cells rather than by replacing an individual cell. In other words, a row containing a defective memory cell is replaced by a redundant row containing only operating memory cells.
It will be apparent that the use of redundant memory cells further requires inclusion of a control circuit so that associated encoders or decoders will properly address the selected redundant row or column of memory cells in response to an address for a row or column containing the defective memory cell. It will also be apparent that the control circuit includes one or more circuit elements for storing information, elements for selecting between groups of memory cells, and some additional device for programming the information storing elements. U.S. Pat. Nos. 4,606,830 and 4,707,806 disclose examples of this type of control circuit. IBM Technical Disclosure Bulletin Vol. 27, No. 11 (April 1985) discloses a programmable address inverting circuit wherein the condition of a fuse or programmable link provides selected switchable complementary output signals used in driving an address buffer. The logical extension of such control circuits is to provide built-in self repair circuits, such as that disclosed in Sawada et al., "Built-in Self-Repair Circuit for High-Density ASMIC," IEEE Conference of Custom Integrated Circuits, pages 26.1.1-26.1.3 (1989), for VLSI devices.
Fusible links are known for redundancy-programming a variety of semiconductor devices, including the RAM device discussed above. Fusible links are either open or closed, thus effectively storing "0" or "1" values. These links are generally programmed by either applying a predetermined voltage directly to the fusible link or by applying an external energy source such as a laser beam to the fusible link. U.S. Pat. Nos. 4,042,950 and 4,135,295 disclose fusible links closed by a predetermined voltage applied to the link, which produces a current density greater than the required fusing current, thus removing an insulating layer and closing, i.e., shorting, the fusible link. U.S. Pat. No. 4,670,970 discloses a normally open fusible link which closes by solid phase diffusion of metal into a silicon layer to produce a conductive silicon layer. U.S. Pat. No. 4,446,534 discloses a circuit including a fusible link which is programmed by applying a voltage of opposite polarity rather than a relatively high voltage of normal polarity. U.S. Pat. No. 4,455,495 discloses a fusible link of the second type wherein a non-conductive element is short circuited by application of a laser beam. Of course, devices are also known where fusible links are programmed by application of both a predetermined voltage and a laser beam, such as that disclosed in U.S. Pat. No. 4,912,066.
In recent years, redundancy-programming using an applied laser beam has become the programming method of choice. However, this programming method has several disadvantages. Programming mechanisms for this type of programming are expensive, often costing in excess of a million dollars per work station. In addition, laser redundancy-programming is relatively slow due both to the need to select the individual fusible links to be programmed as well as to the need for post-programming fabrication steps such as clean up of the area, e.g., the blast crater, around the fusible link. It will also be appreciated that continually increasing device densities will eventually produce element spacing so small that laser programming cannot be accomplished without at least partial damage to adjacent elements, which will, of course, result in reducing the mean time between failures for these high density devices. Moreover, misalignment between the laser spot and the fuse to be blown may lead to incomplete or inaccurate fuse blow, which could actually detract from the overall process yield. Other problems associated with programmable fusible links are discussed in U.S. Pat. No. 4,546,454.
Control circuitry, which includes fusible links for redundancy-programming, is disclosed in U.S. Pat. Nos. 4,571,707 and 4,609,830. In addition, circuitry for detecting the condition or state of fusible links includes the coincidence detection circuit of U.S. Pat. No. 4,707,806, as well as the circuit employing a flip-flop, which includes a plurality of conventional fuses, disclosed in U.S. Pat. No. 4,837,520.
During recent years, it has been reported that current-induced resistance decreases in heavily doped polysilicon resistors is possible. See Kato et al., "A Physical Mechanism of Current-Induced Resistance Decrease in Heavily Doped Polysilicon Resistors," IEEE Transactions on Electron Devices, Vol. ED28, No. 8, pages 1154-61 (August 1982). Resistance decreases of up to 50 percent, which are controllable within an accuracy of 0.01 percent, were reported. Another antifuse concept is described by Hamdy et al., "Dielectric Based Antifuse for Logic and Memory ICs," Transactions of the International Electron Device Meeting, pages 786-789 (San Francisco, December 1988), which discloses the use and programming of a polysilicon insulator-diffusion sandwich which is programmed by rupturing the insulator between the two conducting layers at high voltage (18 V). An additional programmable scheme is described by Y. Shacham-Diamand et al. in "A Novel Ion-Implanted Amorphous Silicon Programmable Element," International Electron Device Meeting, Digest 1987, pages 194-197 (Washington, D.C., 1987). The method consists of creating a highly resistive amorphous layer by heavy dose ion-implantation and switching the layer to low impedance by applying a programming voltage to the layer.
The use of polycrystaline silicon in semiconductor devices is known for fabricating electrically tunable resistors, such as disclosed in U.S. Pat. No. 4,210,996, as well as other structures including photoconductor sites, as disclosed in U.S. Pat. No. 4,821,091. The fact that the resistance of a polycrystaline silicon resistor varies linearly according to the magnitude of an applied voltage, once a threshold voltage has been applied, has also been used in switching circuitry, such as the read only memory (ROM) device disclosed in U.S. Pat. No. 4,146,902, and control signal generating circuitry disclosed in U.S. Pat. No. 4,399,372. Methods for manufacturing semiconductor devices from polycrystaline silicon are disclosed in U.S. Pat. Nos. 4,229,502 and 4,309,224. However, the programming of antifuse polysilicon devices generally requires application of tens of volts in order to produce the required current density necessary to induce resistance changes in the polysilicon. Given the high densities and short channel lengths of current integrated circuitry, application of such high voltage/current stresses should be avoided if possible.

Low voltage programmable storage element

International Business Machines Corporation


A process for producing a 3D tissue culture model by (a) printing a drop of bio-ink to a substrate; (b) printing a drop of activator to the drop of bio-ink to form a hydrogel droplet; (c) repeating steps (a) and (b) in any order to form a hydrogel mold adapted to receive a drop containing cells; (d) printing a drop containing cells to the hydrogel mold; and (e) repeating steps (a) and (b) in any order to form a 3D tissue culture model comprising the cells encapsulated in the hydrogel mold.

Most cell structures in the human and animal body are organised in three-dimensions. This leads to complex intercellular interactions that cannot be mimicked in two-dimensional monolayers of cell cultures (Pampaloni, Ansari and Stelzer, 2013). However, two-dimensional cell culture has been the paradigm for typical in vitro cell culture. It has been demonstrated that cells behave more natively when cultured in three-dimensional environments but the formation of three-dimensional cell culture is difficult, expensive and laborious to generate.
Cellular spheroids are an example of a three-dimensional cell culture model and was among the first to be discovered and applied in basic research and clinical pharmacology. Cellular spheroids are aggregated cell clusters with a typical diameter of hundreds of microns. There are many techniques currently available for spheroid formation, such as the hanging drop method or rotational stirrers. Typically, culturing a cellular spheroid can take up to four days and has a 50% success rate.
Numerous studies have reported the printing of cells using drop-on-demand type technology. Faulkner-Jones et al. (2013) printed cells suspended in medium using the drop-on-demand method with a cell density of approximately 1×105 cells/ml in DMEM. Ferris et al. (2015) reported the printing of 2×106 cells/ml in bio-ink (gellan gum) using a commercially available inkjet printhead. Xu et al. (2014) reported the printing of cells in bio-ink at a density of 1×107 cells/ml. It was also reported that the most widely used cell concentrations in cell printing are between 105 and 107 cells/ml. While many previous studies describe printing of cells using drop-on-demand technology, there are no reports of printing a high cell density (greater than 107 cells/ml) in bio-ink via the drop on demand method.
In order to form a cellular spheroid, for example, a high density of cells (5×107−2×108 cells/ml) must be aggregated into a small spherical cell cluster. The hanging drop technique achieves this by suspending droplets of culture medium containing isolated cells and allowing the cells to aggregate over three to seven days. Generating cellular spheroids using a drop-on-demand device presents difficulties due to the high viscosity associated with high cell densities and the small feature size in a drop-on-demand device. For this reason, in previous attempts to print tissue structures using spheroids, the cellular spheroids were firstly formed manually, loaded into a 3D printer and then printed to form a tissue structure. Tan et al. (2014) reported the 3D printing of preformed cellular spheroids via the extrusion method. Tan et al used a pressurised Pasteur pipette system as the droplet dispensing nozzle, which resulted in a continuous deposition of preformed spheroids. Marga et al. (2012) also reported the 3D printing of preformed spheroids via the extrusion method. In contrast, capillary micropipettes were used to contiguously arrange the cellular aggregates in a single line. Similarly, Mironov et al. (2009) also reported the 3D printing of preformed cellular spheroids via the extrusion method.
The present inventors have developed a process for preparing a 3D tissue culture model suitable for in vitro cell culture assays.

Process for printing 3D tissue culture models


A slidable drawer system is provided for mounting below a stationary shelf or cupboard which does not require later support or side rails, but rather utilizes guide rails which receive flanges extending outwardly from the tops of the sidewalls. Thus, the guide rails are mounted directly to the bottom of the shelf or are spaced from the bottom surface in the case of cupboards with an underhang. A resilient finger is provided on the guide rail to engage with the rear wall of the drawer to prevent accidental disengagement of the drawer from the rails while permitting selective disengagement.

1. Field of the Invention
The present invention relates to a drawer system and more specifically to a sliding drawer or shelf mounted on rails beneath a cabinet or fixed shelf.
2. Description of the Prior Art
In many kitchens, bathrooms and other rooms cupboards and cabinets are utilized for storing various items and generally the shelves on which the items are stored are fixed horizontally rather than being slidable with respect to the cabinet or frame of the shelf unit. Where slidable shelves or drawers are provided, generally side rails are utilized for the shelf to slide on which require that there be some lateral support for carrying the rails.
In some shelf units, the shelves are spaced quite widely and the entire area between shelves is not utilized. Also, in cabinet and shelf units which are suspended on a wall above the floor or above a counter surface, the space below the cabinet or shelf unit may not be completely utilized.
Therefore, it would be desirable to have a shelf or drawer unit which could be attached to areas of inadequate utilization to increase the storage capacity of the cupboard or shelf unit.


An electrical connector having a noise-proof metal shell includes a particular construction of the metal shell capable of maintaining reliable connecting condition between the metal shell and grounding elements without causing any faulty connection therebetween even if the connector is used under a condition prone to vibration or suffered from shrinkage occuring in an insulating block of the connector due to aging.

This invention relates to an electrical connector having a noise-proof metal shell, and more particularly to an electrical connector having an improved connection between a noise-proof metal shell and a grounding element to be connected to a ground.
A connector having at contacts 1 a metal shell 2 for preventing inductive interference as shown in FIG. 1 has been used as a so-called "interface connector" for connecting a printed circuit board and an input circuit in a so-called office automation appliance such as a personal computer.
Such a connector generally includes the desired number of the contacts 1 having L-shaped contact tails 1a and fixed in an L-shaped insulating block 3, and hexagonal studs 4 threadedly engaging connecting pieces 5a of L-shaped grounding elements 5 to embrace a mounting flange 2a of the metal shell 2 and connecting pieces 3a of the insulating block 3. In using the connector, it is fixed to a printed circuit board 6 in the following manner.
First, the contact tails 1a of the contacts 1 are inserted into soldering apertures 7 formed in a circuited pattern 6a of the printed circuit board 6 as shown in FIG. 1. Thereafter, fixing pieces 5b of the grounding elements 5 and the printed circuit board 6 together with a fixing piece 3b of the insulating block 3 are clamped by means of set screws 8 and nuts 9 so that these members are embraced by the nuts 9 and heads of the set screws. In this manner, the metal shell 2 is connected to the ground pattern 6b of the printed circuit board 6 for use.
Moreover, each hexagonal stud 4 is often formed with an internal thread (not shown) in an end which is not connected to the grounding element 5. The internal threads of the hexagonal studs 4 are adapted to threadedly engage screw thread members (not shown) rotatably provided on a mating connector (not shown) so that the hexagonal studs 4 are frequently used as part of locking means for preventing dislodgment of these connectors.
With this connector of the prior art, the metal shell 2 is readily removed from the connector by loosening the hexagonal studs 4 so that it is very convenient for maintenance, inspection and cleaning for the contacts 1. In case of being used under a condition prone to vibration, however, there is a risk of the hexagonal studs 4 being loosened during use. Moreover, a plastic material of the insulating block 3 may shrink due to aging to loosen the tightness of the hexagonal studs 4. Therefore, connection between the metal shell 2 and the grounding elements 5 for grounding the metal shell 2 may become faulty with the result that the noise preventing effect is reduced and the reliability in operation is lost.
Instead of the locking means of the threaded engaging hexagonal studs 4 as shown in FIGS. 1 and 2, another means may be used for preventing dislodgment of the connector. In this case, a metal shell of a connector is provided with locking members formed with openings in which hook pieces fixed to a mating connector are latched. In this case, the locking members may be formed by extending the mounting flange 2a outwardly of hexagonal studs 4 or by providing an additional member constituting the locking members. In any case, such a construction will provide a longer connector which does not fulfill the requirement of miniaturization of connectors with the recent tendency of electronic appliances to be miniaturized.
In case of using the hexagonal studs 4, moreover, arranging and tightening steps of the screw members are required which make difficult automatic assembling of connectors and do not meet the requirement to reduce the number of parts.


The present invention relates to dentifrice and its method of manufacture whereby the dentifrice containing tannic acid efficacious for the prevention of outbreak of tooth decay, pyorrhea and gingivitis can be obtained by means by adding what is obtainable through adding tannic acid to hot water whereto glycerine is added after it has become cooled down to the materials for the dentifrice and mixing them together.

The present invention relates to dentifrice containing tannic acid efficacious for the prevention of tooth decay, pyorrhea and gingivitis and to its method of manufacture.
In the field of dental treatment, various studies are being made of late of making oral medicines or dentifrice containing fluorides with the object of preventing or decreasing prevalence of tooth decay in the knowledge that the average rate of outbreak of patients suffering from tooth decay is comparatively lower for those who live in the regions where fluorine is contained in the drinking water in the form of fluorides in a period when their teeth are coming into being and are growing. However, the fact is that the number of patients suffering from tooth decay is increasing year by year in every country of the world and it is a question to what extent the oral medicines and dentifrice containing fluorides respectively are efficacious for the prevention of tooth decay.
Let us examine here the influence of fluorine upon the human body. Fluorine itself is one of the inorganic micro-elements in the human body and principally exists in the enamel of a tooth as well as in cartilage, skin, blood etc. The function of fluorine in the human body, however, remains unexplained. When ordinary drinking water in a region contains 2.7-5 ppm of fluorine, the region is called a fluorine region and this amount of fluorine may cause mottled tooth. It is regarded that a fluorine content of 1-2 ppm in the case of infants in particular and that of 0.8 ppm in the case of milk teeth may bring about a danger of outbreak of mottled tooth. On the other hand, as the flurine content in a decayed tooth is 0.0069% which is less than that of 0.0111% in a healthy tooth, it is considered that about 0.7 ppm of fluorine content in the drinking water is efficacious for the prevention of outbreak of tooth decay. But this amount alone does not make a perfect dental medicine against tooth decay. However, as a preventive measure against tooth decay in general, there are such methods as adding a little amount of fluorine to drinking water, application and addition of soda fluoride to dentifrice. Of the above, the addition of fluorine to drinking water is the most efficacious when it is conducted at the time when the teeth absorb calcium, or from the 4th month of pregnancy to one year in the case of milk teeth and before the age of 7 or 8 in the case of permanent teeth. Accordingly, the method of applying soda fluoride is the most efficacious when it is conducted before they cut their milk teeth and permanent teeth. Though fluorine has a function of reinforcing a formative substance of teeth as mentioned above, however, it has no function to kill bacilli. It is therefore impossible to remove causes of tooth decay only with fluorine and the application of fluorine is of no use when caries is already in an advanced stage. However, as mentioned above, water containing a soluble inorganic fluoride is efficacious for the prevention of caries and, making use of this property, various trials are made of adding soluble fluoric inorganics producing fluorine ion to dentifrice to put them to some use for the prevention of tooth decay.
As for such a soluble inorganic fluoride producing fluoric ion, it must be a substance which does no harm to the mucous membrane of the mouth, and the kinds are accordingly limited and only the fluoride of alkali metal such as soda fluoride, silicofluoride of the group of alkaline earths and tin fluoride or aluminum fluoride etc. are used under the existing circumstances. However, in the case of a dentifrice, when a soluble inorganic is added to such bases as calcium carbonate and calcium phosphate, ion dissociation takes place affected by the water contained in the dentifrice and the dissociated ion joins with calcium to become insoluble calcium fluoride resulting in eduction and, as this cannot penetrate into the tooth canaliculi, the prevention of tooth decay by fluorine ion proves inefficacious in practice. The reason why resin has come to be used as a material for dentifrice seems to lie in the fact that it does not contain polyvalent metallic ion. In spite of many efforts which have been exerted for the past tens of years to find out any satisfactory preventive medicine containing fluorine, nothing has so far been discovered which can satisfactorily be used by both dental surgeons and people in general. The fact that these sorts of dentifrice contain fluoric ions in the form which is difficult to be utilized seems to be the reason why they are not used with satisfaction as mentioned above.

Dentifrice and its method of manufacture


A method of forming a gate dielectric layer includes forming a first dielectric layer over a semiconductor substrate using a first plasma, performing a first in-situ plasma nitridation of the first dielectric layer to form a first nitrided dielectric layer, forming a second dielectric layer over the first dielectric layer using a second plasma, performing a second in-situ plasma nitridation of the second dielectric layer to form a second nitrided dielectric layer; and annealing the first nitrided dielectric layer and the second nitrided dielectric layer, wherein the gate dielectric layer comprises the first nitrided dielectric layer and the second nitrided dielectric layer. In other embodiments, the steps of forming a dielectric layer using a plasma and performing an in-situ plasma nitridation are repeated so that more than two nitrided dielectric layers are formed and used as the gate dielectric layer.

1. Field
This disclosure relates generally to integrated circuits, and more specifically, to forming gate dielectrics for transistors of an integrated circuit.
2. Related Art
Gate dielectrics are a very significant factor in the performance of a transistor and thus the performance of an integrated circuit made up of such transistors. The historic preferred gate dielectric has been a silicon oxide grown at very high temperature. This is often called a thermally grown oxide. Reducing the thickness of a gate dielectric is a known way of enhancing coupling between gate and channel and thus improving speed but adversely effects leakage and reduces breakdown voltage. Thus much work has been done in developing high K dielectrics for use as a gate dielectric so that gate to channel coupling is enhanced but enough thickness is retained to have low leakage and reasonable breakdown voltage. The most promising of the high K materials have been various metal oxide. There have been many difficulties in obtaining the desired result for metal oxides. One problem is growing an excessively large interfacial oxide layer at the interface with the substrate, which is most commonly silicon. This interfacial oxide layer is very difficult to prevent completely, but it is preferably as thin as possible. In order to minimize the interfacial oxide thickness, the oxygen concentration applied in the formation of the metal oxide is kept as low as possible to form the metal oxide. A problem arising from keeping the oxygen concentration relatively low is that the resulting metal oxide layer has oxygen vacancies, locations where oxygen atoms should be present but are not present. The oxygen vacancies, when excessive, cause a reliability problem. With usage, the threshold voltage shifts. The direction of the shift depends on the particular metal oxide used, but it is a reliability problem either way. If the magnitude of the threshold voltage decreases, the transistors may not turn off completely and cause excessively leakage and may even result in a logic operational failure. If the magnitude of the threshold voltage increases, the speed of operation can decrease excessively and either reduce the speed of operation below the required speed or even cause an operational failure.
Nitrogen has been used to fill the oxygen vacancies and reduce Hf dangling bonds to prevent the attendant reliability issues. A benefit of using nitrogen is that there is also an increase in the dielectric constant. A problem with nitrogen is that nitrogen atoms at the interface with the substrate can reduce the mobility in the channel. Thus, it is desirable for nitrogen to be present in most of the thickness but not at the interface with the substrate. This has been difficult to achieve, especially while continuing to minimize interfacial oxide growth. Ammonia NH3 as a source of nitrogen does well in filling the vacancies but reaches the substrate very easily so the resulting nitrogen concentration is undesirably high at the interface with the substrate. In addition, hydrogen release during an ammonia anneal degrades gate oxide quality.
Accordingly, there is a need for a method for obtaining nitrogen in a metal oxide gate dielectric that avoids or reduces one or more of the problems described above.

Method of forming a gate dielectric by in-situ plasma


This invention is directed to a method of preparing a natural resin by liquefying wood, bark, forest residues, wood industry residues, or other biomass using rapid destructive distillation (fast pyrolysis). Fast pyrolysis produces both vapours and char from biomass, and following removal of the char from the product vapours, a liquid pitch product is recovered and processed by distillation, evaporation, or a combination thereof, in order to obtain a natural resin which may be in either liquid or solid form. The natural resin comprises a total phenolic content from about 30% to about 80% (w/w), and is a highly-reactive ligninic compound that has been found to be suitable for use within resin formulations without requiring any further extraction or fractionation procedures. Resins comprising up to 60% natural resin have been prepared and tested in board production and found to exhibit similar properties associated with commercially available resins. The natural resin may substitute for phenol, or for both phenol and formaldehyde within phenol-containing resins. Similarly, the natural resin can replace a substantial part of the components within urea-containing resins.

xe2x80x9cResinxe2x80x9d is a generic term used to describe both natural and synthetic glues which derive their adhesive properties from their inherent ability to polymerize in a consistent and predictable fashion. The vast majority of modern industrial resins are synthetic, and are normally derived from petroleum feedstocks. Two of the most important classes of synthetic resins, in terms of production volume and total sales are phenol formaldehyde (P/F) and urea formaldehyde (U/F) resins. In both cases, the principal market application is for use as a glue binder in man-made wood products.
Phenol formaldehyde (P/F) resin, because of its resistance to moisture, has a particular value in external (outdoor) or damp environments. It is therefore, the leading adhesive used for the manufacture of plywood, oriented strand board (OSB) and wafer board (Sellers, 1996). P/F resins are also widely used in laminates, insulation, foundry materials, moulding compounds, abrasives and friction materials for the transportation industry (i.e., clutch facings, disk facings and transmission components). As its name suggests, the principal ingredients in P/F adhesives are phenol and formaldehyde. However, the finished product is actually a mixture of P/F, caustic, and water. Assorted fillers, extenders and dispersion agents may then be added for specific adhesive applications.
The formaldehyde ingredient in P/F resin is derived from methanol, normally produced from natural gas. The phenol ingredient is typically manufactured from benzene and propylene via a cumene intermediate. In addition to P/F adhesive manufacture, phenol is used in the manufacture of other important products, for example, Bisphenol A and Caprolactam. Bisphenol A is a principal component in polycarbonates used in automotive parts, compact discs and computer discs, and Caprolactam is a raw material for Nylon 6, used within stain resistant carpets.
When mixed together in water and with caustic added as a catalyst, phenol and formaldehyde undergo a condensation reaction to form either ortho- or para-methylolphenol. The resultant PF resin, as shipped to market, is a dark brown liquid which is polymerized and cross-linked to an intermediate degree. It is then cured in the final board, laminate or other product without catalyst simply with the addition of heat at which time the final polymerization and cross-linking take place via condensation reactions. The release of free formaldehyde during the resin manufacture and resin use stages is a concern from a health and safety perspective. Furthermore, the costs associated with formaldehyde production have increased and there is a need in the art for alternative materials for use as wood adhesives and binders.
One alternative for phenol that has been considered are lignins which have been recovered from wood, wood residues, bark, bagasse and other biomass via industrial or experimental processes. Natural lignin (i.e. the polymer which occurs in nature which holds wood and bark fibres together and gives wood its strength) and P/F formaldehyde resins are structurally very similar. Lignin is a random network polymer with a variety of linkages, based on phenyl propane units. Lignin-based adhesive formulations have been tested for use within plywood, particle board and fibre board manufacture. The addition of polymeric lignin to P/F formulations has been found to prematurely gel the P/F resin thereby reducing shelf life, limiting permeation of the lignin-P/F resin into the wood and producing an inferior mechanical bond (Kelley 1997). It is important to note that lignins which are isolated and recovered from biomass, and which have been tested in resin formulations, are not identical to the natural lignin present in the original biomass, but are altered somewhat by the recovery process. Some examples of recovered lignins which have been tested in PF resin formulations are Kraft lignin, lignosulphonates, Alcell(trademark), Organocell(trademark), pyrolytic lignin and natural resin of the present invention.
Pyrolysis of lignin has been considered as a potential approach to upgrading lignin to more usable phenolic type resins. While relatively mild thermal or thermo-catalytic processing at low pressures can be used to break the lignin macromolecules into smaller macromolecules, lignin segments and monomeric chemicals, such procedures may cause condensation reactions producing highly condensed structures such as char and tar, rather than depolymerized lignin fragments or monomeric chemicals.
A further alternative for the production of phenolic compounds involves use of pyrolytic pitch oils produced in the rapid destructive distillation (fast pyrolysis) of wood and other biomass. These pyrolytic oils are comprised of a complex mixture of compounds including phenolic compounds, guaiacol, syringol and para substituted derivatives, carbohydrate fragments, polyols, organic acids, formaldehyde, acetaldehyde, furfuraldehyde and other oligomeric products (Pakdel et al 1996). However, wood-derived lignin and lignin-rich pyrolytic bio-oils have lacked consistency and have exhibited inferior properties when compared with phenol-formaldehyde resins (Chum et al. 1989; Scott 1988; Himmelblau 1997; Kelley et al., 1997).
Due to the complexity of pyrolytically-derived bio-oils, further processing is required in order to obtain suitable fractions useable as a replacement for phenol, or to be considered as an extender for petroleum-derived phenol within P/F resin formulations. Typically the phenolic derived from pyrolysis oils requires separation prior to use in order to remove impurities. One such method involves water extraction of the whole-oil, followed by precipitation and centrifugation or filtration and drying of the non-aqueous fraction to prepare a xe2x80x9cpyrolytic ligninxe2x80x9d fraction (Scott 1988). However, adhesive formulations prepared using pyrolytic lignin were found to be inferior to P/F resin formulations in both colour and odour, and required long press times in order to avoid de-lamination of waferboards. Tests indicated that none of the pyrolytic lignin samples meet the internal bond (IB) test requirement (Scott 1988, see pp. 91-92).
In U.S. Pat. No. 4,209,647 (Jun. 24, 1980) a fractionation method for the preparation of a phenol-enriched pyrolytic oil is disclosed which involved a multistep process that selectively solubilized neutral phenols, and organic acids of the whole-oil with NaOH followed by extraction with methylene chloride. However, this multistep process is costly, laborious, time consuming and involves the use of volatile solvents that are known to be health threatening.
Another fractionation method involves adding ethyl acetate to whole-oil pitch to produce ethyl acetate soluble and insoluble fractions. The ethyl soluble fraction is then isolated and the ethyl acetate evaporated to isolate a fraction containing phenolic and neutrals (P/N) derived from the pyrolytic oil (Chum et al. 1989, U.S. Pat. No. 4,942,269, Jul. 17, 1990, and U.S. Pat. No. 5,235,021, Aug. 10, 1993). Preliminary results with the P/N fractions revealed that fractionated pyrolytic oils could be used within P/F resin compositions, as P/N containing resins exhibited equivalent gel times as noted for P/F resins. However, the fractionation protocol is not suitable for industrial scale production, nor is this process cost effective for the preparation of alternative components for use within P/F resins at a commercial scale (Kelley et al., 1997).
All of the process disclosed within the prior art as outlined above involve the extraction of a phenol-enhanced fraction from the whole pyrolytic oil product using complex protocols involving precipitation, followed by centrifugation or filtration, or the use of solvents and alkali. None of the prior art discloses methods for the production of a bio-oil which is readily prepared from the whole pyrolytic oil or that exhibits properties suitable for adhesive use. Furthermore, the prior art does not disclose methods directed at producing a fraction of bio-oil suitable for adhesive use, yet that is simple to produce and that does not require any solvent extraction.
It is an object of the invention to overcome disadvantages of the prior art.
The above object is met by the combinations of features of the main claims, the sub-claims disclose further advantageous embodiments of the invention.
The present invention relates to the production and use of a natural resin, a highly reactive ligninic product, derived from wood, bark and other biomass residues using rapid destructive distillation, for example, fast pyrolysis. Specifically, the natural resins (NR) of this invention are obtained from the fast pyrolysis of wood products. The NR is obtained from a ligninic fraction of the liquid pitch product produced from fast pyrolysis of biomass.
By the processes of the present invention, there is no need to extract a phenol enhanced portion using solvents, water induced solids separation, or alkali. Rather the NR of this invention may be produced from a selected product fraction of the whole-oil obtained from the pyrolytic process, or from the whole-oil product. The whole-oil, selected product fraction, or a combination thereof, is processed in a manner that reduces non-resin components including odorous components and acids in order to produce NR. Such a processing step involves distillation/evaporation.
The natural resins (NR) of the present invention can be used as a substitute for some of the phenol in phenol/formaldehyde, phenol urea formaldehyde, and phenol melamine urea formaldehyde resins used as adhesives in the manufacture of wood products, or the NR can be used as a substitute of some of the phenol and some the formaldehyde components of phenol-containing formaldehyde resins, for example industrial phenol-formaldehyde resins. Furthermore, the NR of this invention can be used as a substitute within urea formaldehyde resins, and melamine urea formaldehyde, and related resins. The natural resins of the present invention can be used as a substitute for either some of the phenol component of a phenol-containing formaldehyde resin or for both the phenol and formaldehyde components of the resin, or as a substitute within urea formaldehyde type resins.
The natural resins of the present invention exhibit high reactivity due to the presence of a high number of active sites for binding and cross linking during polymerization.
According to the present invention there is provided a method of preparing a natural resin (NR) comprising:
i) thermally converting a suitable biomass via rapid destructive distillation in order to produce vapours and char;
ii) removing the char from the vapours;
iii) recovering the vapours to produce a liquid pitch product;
iv) processing the liquid product using distillation/evaporation to produce the NR.
The present invention embraces the above method, wherein the step of processing uses the liquid product obtained from a primary recovery unit, a secondary recovery unit, or a combination thereof.
This invention also pertains to the above method wherein the step of processing comprises the addition of water to the NR to produce an NR with reduced viscosity.
This invention relates to the above method wherein the step of processing comprises removing essentially all of the water content of the NR to produce a solid NR.
Furthermore, the present invention relates to the method as defined above wherein the step of processing comprises pretreating the liquid product prior to distillation/evaporation. Preferably, the step of pretreating comprises a water wash to reduce viscosity, improve flowability into downstream equipment and enhance the removal of non-resin components.
This invention is also directed to a natural resin (NR) characterized by comprising a water content up to about 20%, pH of about 2.0 to about 5.0, and acids content from about 0.1 to about 5 (dry wt %) and a viscosity of about 6 to about 130 cST (@70xc2x0 C.) for liquid NR, or the NR may be solid NR.
This invention is also directed to a resin composition that comprises the NR as defined above. Furthermore, this invention is directed to a resin composition comprising NR from about 1% to about 40% (w/w) of the resin composition.
This invention is also directed to a resin composition as defined above comprising a phenol-containing or urea containing formaldehyde resin. Furthermore, this invention relates to a resin composition as defined above wherein the phenol-containing or urea-containing formaldehyde resin is selected from the group consisting of phenol formaldehyde, urea formaldehyde, phenol melamine urea formaldehyde, melamine urea formaldehyde, and phenol urea formaldehyde.
This invention also relates to a resin composition as defined above wherein the NR comprises from about 20 to about 40% (w/w) of the resin composition. Furthermore, the resin composition of this invention may further be characterized in that a portion of the formaldehyde, within the formaldehyde-phenol resin is replaced with NR, and wherein the NR replaces up to about 50% of the formaldehyde content of the resin. Preferably the adhesive composition comprises a formaldehyde: phenol ratio from about 1.2:1 to about 3:1. This invention is also directed to a resin composition wherein a portion of the phenol within a formaldehyde phenol resin is replaced with NR.
This invention also relates to mixtures of natural resin, comprising whole-oil and fractions of whole-oil. Furthermore, this invention is directed to adhesive compositions and industrial resins comprising natural resin mixtures. This invention also includes phenol-containing formaldehyde resins comprising natural resin, or natural resin mixtures that replaces up to 100% of the phenol content of the phenol-containing resin.
This invention also embraces a wood product prepared using the adhesive compositions as defined above. Preferably, the wood product is selected from the group consisting of laminated wood, plywood, particle board, high density particle board, oriented strand board, medium density fiber board, hardboard or wafer board. Furthermore, the wood product prepared using the adhesive composition of this invention is used for exterior, interior or both interior and exterior applications.
This invention also pertains to industrial phenol formaldehyde resin products including mouldings, linings, insulation, foundry materials, brake linings, grit binders, for example to be used within abrasives such as sand paper, and the like.
Use of a fast pyrolysis process to produce the bio-oil is beneficial in that the fast pyrolysis process depolymerizes and homogenizes the natural glue component of wood, that being lignin, while at the same time other constituents are also depolymerized including cellulose and hemicellulose. The beneficial components are enhanced within NR following the step of distillation/evaporation. The yield of NR, depending upon the biomass feedstock and the fraction of bio-oil used for NR preparation via distillation/evaporation, varies from 15-60% of the feedstock and exhibits properties that are useful within, for example, phenol-containing, or urea-containing formaldehyde resin compositions. The natural resin so produced can be substituted for some of the phenol and formaldehyde, content within phenol-containing formaldehyde resins, and such formulations meet or exceed current phenol formaldehyde resin industry specifications. Furthermore, NR can substitute for some of the formaldehyde within urea-containing formaldehyde resins. With removal of the organic acids, the NR can completely substitute for the phenol content in phenol resins, and can also be used within urea-containing formaldehyde resin formulations.
This summary of the invention does not necessarily describe all necessary features of the invention but that the invention may also reside in a sub-combination of the described features.


An improved seal member is provided as a part of an electrochromic device to bond two glass elements together in a spaced-apart relationship. In one embodiment the seal member provides improved adhesion to a reflector/electrode on the third surface of an electrochromic mirror, or to a layer of metal on the second or third surface for an electrochromic light filter. This seal member comprises a mixture of an organic resin scaling system and an adhesion promoter, where the adhesion promotor comprises a first and a second region, where the first region interacts with the reflector/electrode or the metal layer, and a second region that interacts with the organic resin sealing system, and may even chemically react with the organic resin sealing system. In another embodiment the seal member is provided with a coefficient of thermal expansion that is closer to glass than a standard epoxy sealing system.

This invention relates to electrochromic devices and, more particularly, to electrochromic light filters or windows, as well as electrochromic and rearview mirrors having an improved seal member.
Heretofore, devices of reversibly variable transmittance to electromagnetic radiation have been proposed as the variable transmittance element in variable transmittance lightfilters, variable reflectance mirrors, and display devices which employ such lightfilters or mirrors in conveying information. These variable transmittance light filters have included windows. One commercially available device is an electrochromic mirror for motor vehicles. These electrochromic mirrors change from the full reflectance mode (day) to the partial reflectance mode(s) (night) for glare-protection purposes from light emanating from the headlights of vehicles approaching from the rear. Among such devices are those wherein the transmittance is varied by thermochromic, photochromic, or electro-optic (e.g., liquid crystal, dipolar suspension, electrophoretic, electrochromic, etc.) means and where the variable transmittance characteristic affects electromagnetic radiation that is at least partly in the visible spectrum (wavelengths from about 3800 .ANG. to about 7800 .ANG.).
Devices of reversibly variable transmittance to electromagnetic radiation, wherein the transmittance is altered by electrochromic means, are described, for example, by Chang, "Electrochromic and Electrochemichromic Materials and Phenomena, " in Non-emissive Electrooptic Displays, A. Kmetz and K. von Willisen, eds. Plenum Press, New York, N.Y. 1976, pp. 155-196 (1976) and in various parts of Eletrochromism, P. M. S. Monk, R. J. Mortimer, D. R. Rosseinsky, VCH Publishers, Inc., New York, N.Y. (1995). Numerous electrochromic devices are known in the art. See, e.g., Manos, U.S. Pat. No. 3, 451, 741; Bredfeidt et al., U.S. Pat. No. 4, 090, 358;Clecak et al., U.S. Pat. No. 4, 139, 276; Kissa et al., U.S. Pat. No. 3, 453, 038;Rogers, U.S. Pat. Nos. 3, 652, 149, 3, 774, 988 and 3, 873, 185; and Jones et al., U.S. Pat. Nos. 3, 282, 157, 3, 282, 158, 3, 282, 160 and 3, 283, 656.
In addition to these devices there are commercially available electrochromic devices and associated circuitry, such as those disclosed in U.S. Pat. No. 4, 902, 108, entitled "Single-Compartment, Self-Erasing, Solution-Phase Electrochromic Devices Solutions for Use Therein, and Uses Thereof", issued Feb. 20, 1990 to H. J. Byker; Canadian Patent No. 1,300,945, entitled "Automatic Rearview Mirror System for Automotive Vehicles", issued May 19, 1992 to J. H. Bechtel et al.; U.S. Pat. No. 5,128,799, entitled "Variable Reflectance Motor Vehicle Mirror", issued Jul. 7, 1992 to H. J. Byker; U.S. Pat. No. 5, 202, 787, entitled "Electro-Optic Device", issued Apr. 13, 1993 to H. J. Byker et al.; U.S. Patent No. 5,204,778, entitled "Control System For Automatic Rearview Mirrors", issued Apr. 20, 1993 to J. H. Bechtel; U.S. Patent No. 5,278,693, entitled "Tinted Solution-Phase Electrochromic Mirrors", issued Jan. 11, 1994 to D. A. Theiste et al.; U.S. Pat. No. 5,280,380, entitled "UV-Stabilized Compositions and Methods", issued Jan. 18, 1994 to H. J. Byker; U.S. Pat. No. 5,282,077, entitled "Variable Reflectance Mirror", issued Jan. 25, 1994 to H. J. Byker; U.S. Pat. No. 5,294,376, entitled "Bipyridinium Salt Solutions", issued Mar. 15, 1994 to H. J. Byker; U.S. Pat. No. 5,336,448, entitled "Electrochromic Devices with Bipyridinium Salt Solutions", issued Aug. 9, 1994 to H. J. Byker; U.S. Pat. No. 5,434,407, entitled "Automatic Rearview Mirror Incorporating Light Pipe", issued Jan. 18, 1995 to F. T. Bauer et al.; U.S. Pat. No. 5,448,397, entitled "Outside Automatic Rearview Mirror for Automotive Vehicles", issued Sep. 5, 1995 to W. L. Tonar; and U.S. Pat. No. 5,451,822, entitled "Electronic Control System", issued Sep. 19, 1995 to J. H. Bechtel et al. Each of these patents is commonly assigned with the present invention and the disclosures of each, including the references contained therein, are hereby incorporated herein in their entirety by reference. Such electrochromic devices may be utilized in a fully integrated inside/outside rearview mirror system or as separate inside or outside rearview mirror systems.
FIG. 1 shows a typical electrochronic mirror device 10, having front and rear planar elements 12 and 16, respectively. A transparent conductive coating 14 is placed on the rear face of the front element 12, and another transparent conductive coating 18 is placed on the front face of rear element 16. A reflector (20a, 20b and 20c), typically comprising a silver metal layer 20a, covered by a protective copper metal layer 20b, and one or more layers of protective paint 20c, is disposed on the rear face of the rear element 16. For clarity of description of such a structure, the front surface of the front glass element is sometimes referred to as the first surface, and the inside surface of the front glass element is sometimes referred to as the second surface. The inside surface of the rear glass element is sometimes referred to as the third surface, and the back surface of the rear glass element is sometimes referred to as the fourth surface. The front and rear elements are held in a parallel and spaced-apart relationship by seal 22, thereby creating a chamber 26. The electrochromic medium 24 is contained in space 26. The electrochromic medium 24 is in electrical contact with transparent electrode layers 14 and 18, through which passes electromagnetic radiation whose intensity is reversibly modulated in the device by a variable voltage or potential applied to electrode layers 14 and 18 through clip contacts and an electronic circuit (not shown).
Typically seal 22 is made from an organic material and is used to bond two inorganic glass elements together. This may cause problems ensuring adequate seal integrity over long periods of time because of the difference in the coefficient of thermal expansion (CTE) between the seal and the glass transparent elements. In addition, it is known to place a small percentage of glass beads, e.g., 1/2 to 2 percent by weight, into the seal as spacers to ensure uniform spacing of the glass transparent elements. This CTE mismatch problem is pronounced (with or without spacer beads) for electrochromic devices that are operated over a wide temperature range, such as architectural windows and automotive windows. Architectural windows must have adequate seal integrity during summer and winter where the temperature may vary by more than 130.degree. F.
Even before a fourth surface reflector electrochromic mirror was commercially available, various groups researching electrochromic devices had discussed moving the reflector from the fourth surface to the third surface. Such a mirror design has advantages in that it should, theoretically, be easier to manufacture because there are fewer layers to build into a device, i.e., the third surface transparent electrode is not necessary when there is a third surface reflector/electrode. In addition, electrochromic windows have been proposed with a very thin layer of metal for use as an electrode on the second surface or third surface or both surfaces. The advantage of using a thin metal layer for use in a light filter or window is that a lower sheet resistance of the electrode can be obtained. In practice, however, placing the thin metal layer on the second or third surface, or the reflector on the third surface, has been difficult. One reason for this difficulty is that the seal used to bond the two pieces of glass together and hold them in a spaced-apart relationship does not always bond well with certain metals, especially reflective and noble metals.
Consequently, it is desirable to provide an improved electrochromic device having a seal that bonds well to a conductive electrode comprising a metal. In addition, it is desirable to provide an electrochromic device having a seal that has a coefficient of thermal expansion that more closely matches the transparent elements.


This invention relates to an activation apparatus for valves, specifically electromagnetically-activated multiway valves. The activation apparatus exhibits an activation element having a first stop and a second stop, which are arranged in facing-relation to one another, and to a housing projection formed by a graduated opening leading into the valve, so that a movement of the activation element, in the direction of its longitudinal axis, is limited or prevented. On the circumference of the activation element, there is a sealing element which is in sealed contact against the wall of the housing recess or graduated opening, which holds the activation element. The two stops and the sealing element are permanently connected with the activation element so as to form essentially a single-body construction. A valve moving arrangement, formed on the activation member and extending into the valve housing, is movable to an engaged position whereby, operation of the activation member effects manual operation of the valve under emergency or manual conditions.

This invention relates to an activation apparatus for valves, specifically electromagnetically-activated multiway valves.
Such activation devices are used specifically as manual operation devices for solenoid valves, so that in case of a failure of the drive medium for the valve element (power failure, defective coil or armature), the valve element can be placed in a position in which fluid pressure may still be introduced to the device being supplied through the electromagnetic valve.
An activation device of the type described above is known from the German Pat. No. DE 21 58 248. This device exhibits, in an open housing recess of a multiway solenoid valve, an indexing pin, which serves as the activation element, and which can be displaced in the direction of its longitudinal axis and can be rotated by a predetermined amount around its longitudinal axis. The indexing pin is provided with a bevelled groove, into which fits a guide pin, which limits the axial movement and the rotational movement of the indexing pin. The mounting for the guide pin is a hole in the housing transverse to the longitudinal axis of the housing recess. By means of gaskets, which are in grooves running in the circumferential direction of the indexing pin, and which are in sealed contact with the wall bordering the housing recess, the escape of pressure fluid through the gap between the wall of the housing recess and the jacket surface of the indexing pin is prevented. The indexing pin exhibits a bevel, by means of which, when the indexing pin is activated, the armature of the valve, designed as the valve element, is raised from the valve seat.
This known device exhibits several elements required for the guidance and mounting of the activation element in the housing recess, which means that the device entails a relatively high fabrication and installation expense.
There must be grooves worked into the activation element to hold the gaskets. The valve housing must be equipped with an additional hole for the guide and safety pin. When the device is being installed, the activation element must first be fitted with the gaskets, and then, avoiding damage to the gaskets, must be introduced and oriented in the housing recess. Finally, the guide and safety pin must be fitted into the hole in the valve housing which serves as the mounting.

Wabco Westinghouse Steuerungstechnik GmbH & Co.


Apparatus for applying surface-mounted electronic components to printed circuit boards incorporates a fixture for populating an entire board in a single operation. The fixture comprises an array of upstanding open-ended tubular guides rigidly supported in a block of elastomeric material. Component-dispensing magazines are inserted into the guides. Novel ejectors in each magazine dispense components from all of the magazines simultaneously.

1. Field of the Invention
This invention relates to methods and means for applying surface-mounted solid-state electronic components to printed circuit boards during the board assembly process. More particularly it is concerned with methods and means employing a fixed array of component-dispensing magazines for populating an entire board in a single operation.
2. Prior Art
Since the advent of the semiconductor, the ongoing competetive drive in the electronics industry has been to decrease the size, increase the functional capability and performance, and reduce the cost of solid-state devices and integrated circuits incorporating them.
As a result, advances in the field of component technology now provide virtually unlimited flexibility in integrated circuit design. Similarly, improvements in component packaging, and particularly in the packaging of both passive and active devices for surface-mounting, allow existing circuits to be made more compact and more powerful circuits to be compressed into a given space on the printed circuit board.
Conventionally, during the assembly of a surface-mounted printed circuit board, the components are applied to, and temporarily held in place by a layer of solder paste previously silk-screened on to the metallized mounting pads on the surface of the board. When that surface has been populated, the adhesive is cured to ensure the components will not be released on heating, and the board is heated to reflow the solder. When cooled, the solder connects the components to the electrical circuit and permanently secures them to the board.
To take advantage of the previously mentioned developments, methods and means must be provided for populating the printed circuit board with the resistors, capacitors, inductors, diodes, transistors, small outline integrated circuits ("SOICs"), plastic leaded chip carriers (PLCCs), leadless ceramic chip carriers ("LCCCs"), and other components that make the circuit work. For most applications, hand-assembly is not practical. Automated assembling means are clearly called for.
A great deal of effort has gone into the design and construction of such machines. A number of different approaches have been taken. One of these employs an in-line conveyor, or a numerically controlled cartesian drive system to positioned the board being assembled under a succession of component-dispensing heads which mount each component to the board in its predetermined location. Machines of this type are particularly suitable for high-throughput in a high-volume production line environment, but they are generally limited in the number and variety of components they can handle at one time and relatively difficult to modify for changes in board design.
In another type of assembler, computer-operated robotic devices or relatively fixed dispensing heads select the components from a feeder or feeding station and place them in their intended locations on the board. In the robotic machines the pickup moves in X and Y directions and may rotate as well. In the fixed-head autoassemblers, a removeable table positions the board under the dispenser. These highly sophisticated "pick-and-place" devices are adaptable to dispense practically any surface-mounted component rapidly and with great accuracy. Many of them are provided with computerized vision or other position-sensing means to enhance the accuracy of component placement. Intended primarily for high-precision work, these machines are generally limited to medium or low throughput situations. They are extremely sensitive and require highly skilled personnel for their set up, maintenance and operation. Particularly they are very expensive.
A third type of placement machine incorporates a cartesian table and multiple dispensing heads arranged in succession. The heads are generally mounted on a rotating turret, which allows their jaws, fingers, or suction tubes to pick up a component at a feeding station and place it on the board. These pick-and-place machines are roughly comparable in capability to the previously mentioned robotic and fixed-head assemblers and suffer from the same limitations and deficiencies. These machines are generally somewhat less flexible than the robotic or fixed-head assemblers, and like them, most often have only low- or medium-throughput compacity.
Another class of autoassembler provides for the population of an entire board, or part of a board, in a single operation. Some assemblers of this type utilize a fixed array of pipettes or component-grasping means to place a number of electronic parts in their respective locations at one time. Others transfer the components by means of a template on which each component occupies the position assigned to it on a printed circuit board. Another assembler in this category is exemplified by U.S. Pat. Nos. 4,127,432, 4,375,126, and 4,462,737. These devices apply the electronic modules directly to the surface of the board by means of an array of component-dispensing magazines. This is the approach taken in the present invention, with several novel improvements.
As seen in the previously mentioned patents, conventionally the component-dispensing magazines are vertically supported in a rigid lattice-shaped matrix. The components are positioned in the respective magazines and ejected from the magazines by means of one or more sets of rods or pistons which are thrust axially into the magazines. These devices suffer from several serious limitations. For one, the physical constraints imposed by the structure of the matrix itself limits the user's ability to positioned the electronic components on the surface of the printed circuit board. In practice, this limitation mandates that the circuit be designed to conform to the geometry of the lattice work. This requirement is unacceptable for all but the most rudimentary circuit designs.
Similarly, the structure of the matrix narrowly limits the size, shape and polar orientation of the components it is capable of assembling.
Additionally, the mass of the lattice structure limits the density with which the components can be assembled on the board's surface. To reduce the mass of the lattice by employing thinner structural members will result in a weakening of the structure supporting the magazines and the integrity of the assembly apparatus.
Still further, these prior art devices must provide a push-rod assembly for each of the through-holes in the matrix which could be occupied by a magazine, even though in operation the majority of those positions would not in fact be occupied. The use of push-rods driven by a common drive mechanism necessitates the provision of means for compensating for differences in thickness of the various components. These thickness-compensating means, likewise, must be provided for at each of the through-hole positions, whether components are to be dispensed at those positions or not. The complexity of these mechanisms makes them costly to manufacture and difficult to maintain, and severely limits the ability of these machines to respond to changes in circuit design. A principle object of the present invention is to provide a method and means for applying surface-mounted electronic components to printed circuit boards, which offers all of the advantages, and avoids the defficiencies inherent in devices of the type described.
More particularly, an object of this invention is the provision of a novel fixture for positioning a plurality of surface-mounted electronic component dispensing magazines for use in a circuit board assembling apparatus.
Another object is the provision of a surface-mounting assembling machine incorporating the aforementioned fixture.
Still another object is the provision of a fixture and assembly machine of the aforementioned type, which are capable of positioning a large number of surface-mounted components in an single operational step with great accuracy and assured repeatability.
A further object is the provision of a surface-mounting apparatus of the type mentioned, having a minimum number of moving parts requiring machine-disabling maintenance.
A further object is the provision of an assembly machine which can be modified rapidly and easily to conform to changes in printed circuit design, and which does not require highly-skilled personnel for set up, operation or modification.
A still further object is the provision of an apparatus of the type mentioned, which has the capacity to dispense electronic components of widely varying size and configuration, in any orientation, at any selected position in any desired printed circuit design.


A system and method for defining rewriteable data storage media defined by ECMA Standard ECMA-272 2nd edition (1999) for 120 mm DVD rewriteable disk (DVD-RAM) as a write once data storage media and for storing data thereon. The apparatus consists of a data storage device for reading and writing data on the media, the media, a media type indicator in the media, two write protect flags in the user data area of the media, and programming to examine the two write protect flags prior to a write, erase, or format operation. If both flags match and the media type indicator is write once, the drive is prevented from writing to the user data area if both flags are in the data written state. If both flags do not match after two re-reads, an error message is generated. If both flags are in the data unwritten state, data is written to the user data area and both flags are set to the data written state.

The present invention relates to a new category of DVD-RAM optical disk media (herein called xe2x80x9cDVD-WORMxe2x80x9d (Write Once, Read Many), and particularly to one that enables the user to have the capability of allowing data to be written to a sector only once and read many times.
The 120 mm DVD optical disk products available in the market fit into three categories: DVD-RAM, which are writeable, erasable and re-writeable; DVD-R, which is a recordable write-once version; and DVD-ROM, which is a read only version.
DVD-RAM media is composed of a phase change material. The material is constructed such that the recording medium can take on one of two distinct states. One of the states is amorphous and the other state is crystalline. Each of these two states has reflectivity levels that are different. That is, the crystalline state has a high degree of reflectivity while the amorphous state has a lower degree of reflectivity. The difference in reflectivity is detected by the optics and associated circuitry within a DVD-RAM drive. It is this difference in reflectivity that enables data to be recorded and read back.
The process of writing data onto DVD-RAM discs is achieved by a phase change effect typically created in the following manner; the disk is rotated upon a spindle motor contained within the drive. As the disk rotates at a given speed, a laser assembly within the drive heats a minute region [spot] of the disc recording layer. Typically the surface area of the region of the media being heated by the laser is brought to a temperature above its melting point. As the material cools, the area of the media that was effected by the laser beam cools into an amorphous state. This minute region or spot, which is now in an amorphous state, now reflects light at a lower reflectivity level. This minute region of the media will stay in this state until a laser beam that contains sufficient energy returns the molecules to a crystalline state which in effect erases the data as was represented by the amorphous state.
As the laser beam intensity can be modulated at a very high frequency, the area of the disc that is heated is correspondingly very small and can be thought of as a mark or bit. The length of the mark, or the time the laser is turned on, can also be varied so that marks of different duration can be written.
DVD-R discs are considered xe2x80x98write-oncexe2x80x99 in that once the disc is written there is no concern that the data may be erased, overwritten, or altered. For a user to record information on DVD-R discs a unique drive which can write DVD-R media is required. Currently, DVD-RAM drives are unable to write to DVD-R discs. User data which is recorded on DVD-RAM media can be write protected, however, the method of write protection involves the setting (manually done by the user) of a mechanical tab on the cartridge case. When the cartridge is inserted into a DVD-RAM drive, the position of the write protect tab is typically sensed by a mechanical switch within the drive itself. This method of write protection creates areas of concern to the user who wishes to protect data.
The first area of concern is that a user may unintentionally forget to set the write protect tab to the write protect position and thereby allow overwrites of previously recorded data to occur.
The second area of concern is that user data may be intentionally overwritten or altered simply by changing the position of the write protect tab from xe2x80x98read onlyxe2x80x99 to xe2x80x98writexe2x80x99, overwriting or altering the data, and then resetting the position of the write protect tab from xe2x80x98writexe2x80x99 to xe2x80x98read onlyxe2x80x99.
The third area of concern is that the mechanical switch within the drive itself may fail or become intermittent and thereby not provide a reliable method of protecting data.
A fourth area of concern is the storage and use of DVD-RAM media within automated storage libraries. Depending on the design methodology utilized by the manufacturer of the automated storage library, the DVD-RAM media may or may not be stored in cartridges when resident in the library. For example, media may be removed from the cartridge and placed on a tray that is then stored within the library. One of the issues with removing the media from the cartridge is that once the media is removed from the cartridge the write protect capability of the write protect tab is lost. Therefore the user does not have the capability of protecting data when media is stored in this fashion.
Currently the need for a new category of DVD-RAM media is beginning to take shape in the marketplace. This category of media is one that enables the user to have the capability of allowing data to be written to a sector only once and read many times. For the purposes of this document this media shall be termed DVD-WORM (Write Once Read Many). The primary application for this new product type would be any application where data must be stored and protected in it""s original form without the possibility of intentional or unintentional altering or overwriting.
U.S. Pat. No. 5,233,576, issued to Curtis et. al., discloses an apparatus and method for defining magneto-optical disk media and an optical storage device that allows the media to be convertible from writeable to read-only.
The present invention differs significantly from Curtis in a number of ways.
First, there are differences in the underlying media technology. The present invention is to be used with DVD rewriteable media that is of the type known in the industry as xe2x80x9cphase change media.xe2x80x9d Phase change media uses a different write/read methodology than that of magneto-optical. Phase change media is originally in a crystalline state. Phase change data is written by heating a minute region of the media above its melting point. As it cools it takes on an amorphous state. The amount of light read back or returned to the optic assembly in the drive is based upon the degree of reflectivity of the media. Crystalline media will return more light than an amorphous bit. In contrast, magneto-optical drives write data by heating a minute region of the media to its Curie Temperature in the presence of a magnetic field. This sets the magnetic polarity to that of the applied external magnetic field. Magneto-optical drives read data based upon the angle of rotation of the light returned to the optic assembly in the drive.
Second, the international standards used are considerably different. Curtis is based on media structure defined by the ISO Standard 10089 for 130 mm magneto-optical media. In contrast, the present invention is based upon the logical structure as defined by the ECMA standard ECMA-272 2nd edition (1999) for 120 mm DVD Rewriteable Disk (DVD-RAM).
Third, Curtis allows, in the first embodiment, a sector to be written to as many times as desired until the xe2x80x98storage state bitxe2x80x99 has been changed to read-only state. In contrast, the present invention does not allow any rewriting of sectors under any condition. That is, any sector can be written only once. Once the sector is written, write protect flags arc set that protect the data in the written sector.
Fourth, the present invention utilizes two write protect flags to provide an added security level of write protection. In addition, the two write protect flags consist of multiple bytes in each flag. This is a more robust method than Curtis, which uses a single bit for data protection, as the probability of a single bit being misread is much greater than that of a multiple-byte repeating sequence being misread.
Fifth, the present invention is usable whether or not the media is mounted within a cartridge. Magneto-optical media, such as disclosed in Curtis, is typically mounted within a cartridge and is typically not removed from the cartridge. The magneto-optical cartridge can itself provide a write protect capability by the use of a slide switch. Unlike magneto-optical media, DVD-RAM media can be removed from Type II DVD-RAM cartridges or the DVD-RAM media can be purchased not in a cartridge. Once the media is removed from the cartridge, all write protect capabilities are lost. Use of DVD-RAM media not in a cartridge can be found in the industry in autochanger applications. Typically users of DVD-RAM media in this manner do not have write protect functionality available within the drive.
It is proposed that the 120 mm DVD-WORM 2.6 GB disc and the 120 mm DVD-WORM 5.2 GB disc would be identical, note the exceptions defined in this document, to the 2.6 GB and 5.2 GB capacity 120 mm DVD-RAM disc as defined by the following ECMA (European Computer Manufacturers"" Association) standards:
ECMA-273 (1998) Case for 120 mm DVD Rewriteable Disk (DVD-RAM)
ECMA-272 2nd edition (1999) 120 mm DVD Rewriteable Disk (DVD-RAM)
It is proposed that data should be written to and stored on 120 mm DVD-WORM optical disks in a manner consistent with the ECMA-272 standard for DVD-RAM with the following exceptions:
The DVD-WORM media itself would contain identification data that indicates that the media is of the type WRITE ONCE READ MANY (WORM) and is not of the type DVD-RAM.
The user data sectors themselves will contain sector write control information, flags, that will indicate if the user sector is blank (i.e. contains no user data) or if the user sector contains user data.
This identification data and specific sector write control information would differentiate this media type from the current DVD-RAM media types.
Using standard commands delivered to the drive via the standard interface, user data may be written to and read from the DVD-RAM drive that contains DVD-WORM media. The DVD-RAM drive firmware itself would require modification, by the drive manufacturer, to recognize the new DVD-WORM media type and also to perform the write once, read many, function.

System and method for defining rewriteable data storage media as write once data storage media


The invention provides a trench gate type transistor in which the gate leakage current is prevented and the gate capacitance is reduced. A trench is formed in an N− type semiconductor layer. A thin silicon oxide film is formed on a region of the N− type semiconductor layer for the active region of the transistor in the trench. On the other hand, a silicon oxide film which is thicker than the silicon oxide film is formed on a region not for the active region. Furthermore, a leading portion extending from inside the trench onto the outside thereof forms a gate electrode contacting the silicon oxide film. This provides a long distance between the gate electrode at the leading portion and the corner portion of the N− type semiconductor layer, thereby preventing the gate leakage current and reducing the gate capacitance.

1. Field of the Invention
The invention relates to a trench gate type transistor and a method of manufacturing the same.
2. Description of the Related Art
A DMOS transistor is a double-diffused MOS field effect transistor and used as a power semiconductor device for a power supply circuit, a driver circuit or the like. A trench gate type transistor is known as a type of DMOS transistor.
This trench gate type transistor is configured by forming a gate oxide film 215 in a trench 214 formed in a semiconductor layer 212 and forming a gate electrode 216 covering the gate oxide film 215 in the trench 214 as shown in FIG. 48. A body layer and a source layer (not shown) are further formed in the front surface of the semiconductor layer 212 on the sidewall of the trench 214 by double-diffusion in the vertical direction.
A trench gate type transistor is described in Japanese Patent Application Publication Nos. 2005-322949 and 2003-188379.
As shown in FIG. 48, however, at a portion 216S where the gate electrode 216 is led from inside the trench 214 to the outside (hereafter, referred to as a leading portion), there is a problem that leakage current (hereafter, referred to as gate leakage current) occurs between the gate electrode 216 and the semiconductor layer 212. According to the examination by the inventors, this is firstly because the gate oxide film 215 is thin, and secondly because a corner portion 212C of the semiconductor layer 212 faces the gate electrode 216 at the leading portion 2165 with the thin gate oxide film 215 being therebetween and thus electric field concentration occurs in this portion.

Semiconductor Components Industries, LLC


A self-locking push-on clip fastener for securing two components together is disclosed. The clip fastener includes a u-shaped clip body that includes upper and lower legs and a curved end that connects the legs. The clip body has an open end into which the component to be attached is inserted. The legs are movable between an initial, spaced apart arrangement in which the component may be inserted into the clip body, to a final component-engaging position in which the component is captured between the legs. A slidably movable u-shaped trigger is attached to the clip body. A trigger-guiding channel is formed on the inner wall of one or both of the legs of the clip body. The trigger is slidably movable in the channel. An interlock system comprising first and second windows is formed in one of the legs of the clip body and a flange extending from the trigger.

Clip fasteners replace traditional screw fixings in many applications and have may uses in a wide variety of industries. Broadly speaking, clip fasteners are utilized for fastening two or more components together. Challenges faced by industries include different types of tools needed for assembly and different materials to be fastened together. Other challenges include fastening locations, which may offer only limited access for both assembly during manufacture and removal or adjustment during maintenance. Each of these challenges has the potential for increasing assembly cost to manufacturers because of added tooling as well as extra assembly time.
Clip fasteners commonly find utility in the energy and automotive sectors. In the energy sector, clip fasteners are commonly used to hold solar panels to underlying framework. Also in the energy sector, clip fasteners are used to fasten and ground photovoltaic modules and in the fastening of electric cables.
In the automotive sector, clip fasteners have many uses, including in air bag assembly, window construction, instrument panels and interior and exterior trim attachment. These are some examples of the many uses known for clip fasteners.
Modern demands on the design and construction of clip fasteners mean that new clip fastener solutions need to contribute to ease of assembly as used in production (particularly in view of increasing automation) and provide excellent attachment strength, while maintaining high reliability and low production costs. Compliance with the need for standardization and the requirements of the automotive industry has proved challenging to current clip fastener designs.
Accordingly, and as is the case in many industries, known approaches to clip fasteners for use in attaching components together are undesirable and impractical. An improved arrangement for attaching two components together remains wanting.


An apparatus for preparing plasma deposited films comprised of a first electrode means; a second counterelectrode means; a receptable means for the first electrode means, and the second counterelectrode means; a substrate means to be coated contained on the first electrode means, which electrode means has contained therein permanent magnets; a gas inlet means; and a gas exhaust means, wherein a silane gas is introduced into the receptacle in a crossflow direction perpendicular to the axis of the cylindrical member.

This invention generally relates to a process and apparatus for accomplishing the preparation of thin solid films; and more specifically the present invention is directed to an improved process and apparatus for formulating hydrogenated amorphous silicon photoresponsive imaging member by plasma deposition or glow discharge techniques. In one embodiment the present invention envisions an improved apparatus and process for the preparation of a hydrogenated amorphous silicon photoresponsive imaging member by the rapid plasma deposition of amorphous silicon on a cylindrical substrate with magnets therein by subjecting an appropriates gas source material such as a silane gas to decomposition by an electrical discharge subsequent to permitting the gas to flow toward the cylindrical substrate, preferably in a crossward direction or in a direction orthogonal to the cylinder substrate axis. Incorporation of magnets into the cylinder or electrode component contained in the vacuum chamber enables a more efficient, economical, and uniform deposition of hydrogenated amorphous silicon. Additionally, with the process and apparatus of the present invention there is achieved deposition of hydrogenated amorphous silicon in a rapid sequence, that is, for example in some instances there is a doubling of the deposition rate as compared to some prior art processes. Thereafter, the cylindrical substrate containing on its surface deposited hydrogenated amorphous silicon is removed from the vacuum chamber, and can be selected as a photoconductor for incorporation into electrostatographic imaging apparatuses inclusive of electrostatic imaging and printing devices.
Electrostatographic imaging processes with photoresponsive or photoconductive materials are well known. Examples of photoconductors selected include amorphous selenium, alloys of selenium such as selenium tellurium, selenium arsenic, and the like. Additionally, layered photoresponsive imaging members can be selected for electrostatic imaging systems including those containing therein photogenerating substances and charge transport molecules, reference for example U.S. Pat. No. 4,265,990, the disclosure of which is totally incorporated herein by reference. Additionally, the use of hydrogenated amorphous silicon as a photoreceptor material is illustrated in the prior art. Apparently, hydrogenated amorphous silicon possesses a number of advantages in comparison to, for example, amorphous selenium-based materials in that amorphous silicon is of extreme hardness and will not crystallize over extended time periods, even at temperatures as high as several hundred degrees Centigrade. Additionally, amorphous silicon photoconductors have excellent photoelectric properties, high absorption coefficients through the visible region, and are relatively low in useful life cost in comparison to selenium photoconductors, for example. Moreover, amorphous silicon members are capable of ambipolarity as they can be xerographically charged and discharged either positively or negatively in various imaging systems. Further, amorphous silicon can be modified by adding various dopants thereto, such as boron and phosphorus enabling this material to function as p on n type semiconductor devices. Also, amorphous silicon may be alloyed with other elements, such as germanium and tin for the purpose of providing a material which will be photosensitive in the infrared region.
Hydrogenated amorphous silicon, which is classified as a tetrahedrally bonded amorphous semiconductor, can be prepared by known thermal evaporation techniques similar to those selected for the preparation of selenium photoconductor. However, amorphous silicon prepared in accordance with such a process usually has a relatively high dark conductivity, about 10.sup.-3 ohm-cm(.sup.-1), thereby causing the disappearance of any charge from the surface thereof resulting in a substantially useless member for xerographic imaging purposes. Amorphous silicon prepared by the grow discharge of the gas silane results in a material having a much lower conductivity, such as below 10.sup.-9 ohm-cm(.sup.-1) reference for example the Journal of Electrochemical Society, vol. 116, page 77, (1969), Chittick et al; and the Journal of Noncrystallline Solids, Volume 3, pages 255-270, (1970), Chittick et al.. Apparently, in these processes, hydrogen atoms saturate dangling silicon bonds and remove the band gap states causing the Fermi level to move towards mid-gap.
It is believed that the dangling bonds intrinsically incorporated in amorphous silicon can be reduced, and to some extend, controlled by the choice of film deposition conditions. These dangling bonds are apparently present in a density of sufficient magnitude to render films of amorphous silicon prepared by thermal evaporation techniques or sputtering processes unsuitable for semiconductor and photoelectronic purposes. For example, the resulting material cannot be successfully doped and used to produce p or n type operative devices. Further, intrinsic dangling bonds function as recombination sites rendering the resulting film substantially useless for photoelectronic devices. In those situations wherein, for example, amorphous silicon films are prepared in the presence of a reactive gas, the undesirable localized states are removed from the band gas as a result of the intrinsic dangling bond defects being coordinated with fragments of the reactive gas. Examples of reactive gases selected for coordination with the intrinsic silicon dangling bonds include hydrogen gas and fluorine gas.
Accordingly, thermally evaporated silicon generally must contain, for example, hydrogen or fluorine in order to be useful as a photoconductive member. Thus, the preparation of such a material requires processes and apparatus which are vastly different from those required for the familiar thermal evaporation techniques selected for the preparation of chalcogenides.
One known method for obtaining amorphous silicon materials is referred to in the art as the glow discharge process. In this process, the vapor deposition of a silane gas occurs by causing the gas to flow between two electrodes, one of which has a substrate contained therein. As electrical power is applied to the electrodes, the silane gas decomposes into a reactive silicon hydrogen species, which will deposit as a solid film on both electrodes. The presence of hydrogen can be of critical importance since it tends to coordinate with the dangling bonds in the silicon in part, as the mono, di, and trihydrides, thereby serving to passivate these dangling bonds.
Accordingly, thermally evaporated silicon generally must contain, for example, hydrogen fo fluorine in order to be useful as a photoconductive member. Thus, the preparation of such a material requires processes and apparatus which are vastly different from those required for the familiar thermal evaporation techniques selected for the preparation of chalcogenides.
One known method for obtaining amorphous silicon materials is referred to in the art as the glow discharge process. In this process, the vapor deposition of a silane gas occurs by causing the gas to flow between two electrodes, one of which has a substrate contained thereon. As electrical power is applied to the electrodes, the silane gas decomposes into a reactive silicon hydrogen species, which will deposit as a solid film on both electrodes. The presence of hydrogen can be of critical importance since it tends to coordinate with the dangling bond in the silicon in part, as the mono, di, and trihydrides, thereby serving to passivate these dangling bonds.
In another known process, amorphous silicon can be prepared by a sputtering technique wherein a substrate is attached to one electrode, and a target of silicon is placed on a second electrode. These electrodes are connected to a high voltage power supply and a gas which is usually a mixture of argon, and hydrogen is introduced between the electrodes to provide a medium in which a glow discharge or plasma can be initiated and maintained. The glow discharge provides ions which strike the silicon target, and cause the removal by momentum transfer of mainly neutral target atoms, which subsequently condense as a thin film on the substrate electrode. Also, the glow discharge functions to activate the hydrogen causing it to react with the silicon, and be incorporated into the deposited silicon film. The activated hydrogen also coordinates with the dangling bonds of the silicon to form mono, di, and trihydrides.
There is also known an apparatus and process for preparing amorphous silicon films on a substrate, which involves means for directing and accelerating an ion beam from a plasma toward a sputtering target contained within a chamber, which chamber also contains a shield means having a low sputtering efficiency compared to the sputtering target. The shield means is situated between stray ion beams and the vacuum chamber surface. More specifically, the ion beam process involves producing semiconductive films on a substrate comprising generating the plasma; directing and accelerating an ion beam of the plasma toward a sputtering target, the target being contained in a vacuum chamber at reduced pressure; shielding the vacuum chamber surface from stay ion beams, whereby sputtering of the vacuum chamber surface by the plasma is minimized, followed by sputtering the target with the ion beam to sputter the target material; and collecting the sputtered target material as a film on the substrate, the substrate being physically isolated from the plasma generating process and the sputtering process.
While the latter processes may be suitable for their intended purposes, they suffer from a number of disadvantages, including for example, very low rates of material deposition, the inability to obtain uniform coatings over large areas, and the inability to form multilayers without moving or removing the target and/or the substrate.
Additionally, there is disclosed in U.S. Pat. No. 4,265,991 an amorphous silicon photoconductor. This patent describes several processes for preparing amorphous silicon. In one process, there is prepared an electrophotographic photosensitive member which involved heating the electrophotographic member contained in a chamber to temperature of 50.degree. C. to 350.degree. C., introducing a gas containing a hydrogen atom into the deposition chamber, causing an electrical discharge in the space of the deposition chamber in which a silicon compound is present, by electric energy to ionize the gas, followed by depositing amorphous silicon on the electrophotographic substrate at a rate of 0.5 to 100 Angstroms per second by utilizing an electric discharge while raising the temperature of the substrate thereby resulting in a amorphous silicon photoconductive layer of a predetermined thickness.
Further, there is illustrated in U.S. Pat. No. 4,513,022, the disclosure of which is totally incorporated herein by reference, a process and apparatus for formulating hydrogenated amorphous silicon photoconductive members. Thus, there is described in this patent an apparatus for preparing hydrogenated amorphous silicon imaging members comprised of a first electrode means; a second counterelectrode means; a receptable means for the first electrode means and the second counterelectrode means; a substrate means to be coated contained on the first electrode means; which substrate is in the form of a cylindrical member, a gas inlet means, and a gas exhaust means, wherein a silane gas is introduced into the receptable in a crossflow direction perpendicular to the axis of the cylindrical member. The process and apparatus of the present application is similar to that disclosed in the aforementioned patent with the primary exception that with the apparatus of the present application there is included in the cylindrical member permanent magnets thereby permitting the advantages as detailed hereinbefore inclusive of increased deposition rates for the hydrogenated amorphous silicon.
Therefore, there is a need for improved processes and apparatuses for obtaining new films of photoconductive amorphous silicon at increased deposition rates over large areas. Additionally, there continues to be a need for improved processes and apparatuses for formulating hydrogenated amorphous silicon photoconductive members which processes and apparatuses are simple in design, economically attractive and which are susceptible to a batch process. Also, there is a need for processes and apparatuses for obtaining hydrogenated amorphous silicon at deposition rates of greater than 1 micron per hour, and wherein there results uniformity in thickness. Further, there is a need for a more efficient economical process for the preparation of hydrogenated amorphous silicon photoconductive imaging members. Moreover, there continues to be a need for processes and apparatuses for preparing amorphous silicon photoconductive structures having superior mechanical strength, improved chemical stability, and substantially no toxicity problems associated therewith. Further, there continues to be a need for improved processes and apparatuses for obtaining amorphous silicon photoconductors wherein the thickness of the resulting film on a substrate will be axially and radially uniform over a variety of operating conditions. Also, there continues to be a need for improved processes and apparatuses for obtaining amorphous silicon photoconductors wherein virtually all the silane source gas material is converted to amorphous silicon. Additionally, there continues to be a need for improved apparatus for the deposition of amorphous silicon photoconductors, wherein the apparatus can be easily and expeditiously cleaned between depositions to avoid a buildup of material in the deposition chamber. Finally, there continues to be a need for a process and an apparatus which are suitable for the deposition of amorphous silicon and related materials on numerous cylindrical substrates contained in one deposition apparatus such as a vacuum chamber.


A compressor cylinder head cast as a single piece casting to include a cylinder bore portion and a cylinder head. The cylinder head is cast with respective recesses for accommodating an intake valve and a discharge valve, such intake and discharge valves being identical in form and shape and, therefore, being interchangeable so that, during assembly of the cylinder head, no particular attention need be given to which valve is placed in which recess.

For purposes of assembly, the cylinder bore portion and cylinder head of a compressor cylinder normally comprises two parts. The lower portion of the cylinder head is designed as a valve plate for accommodating the intake and pressure discharge valves, with an intake valve spring disposed adjacent the lower side of the intake valve for biasing it toward a closed position. Since the valve plate also limits the compression space or chamber, the juncture between the head and bore portion must be hermetically sealed; this is only assured by extremely precise machining of the edges and by a seal. Compressors in which the valve plate comprises a separate component are also known.
The designs described above, therefore, comprise a large number of individual parts that are expensive to produce. It is conceivable that the number of necessary individual parts could be reduced by combining individual parts in one or a few castings.
However, it has been found that, when several individual parts are simply combined in a single casting, considerable problems are encountered in the mounting of the valve.