An optical scanner has light source units spaced from each other along a first direction and having optical axes parallel to each other. Positions from which the light beams are emitted are spaced from each other by a predetermined distance at least along a predetermined direction. The optical scanner also includes a deflection unit that deflects the light beams together and scans the light beams along a second direction perpendicular to the first direction. The optical scanner also has imaging units that form an image with each of the light beams on a surface and a housing unit that holds the light source units, the deflection units, and the imaging units.

1) Field of the Invention
The present invention relates to an optical scanner used in an optical writing system, such as digital copying machines and laser printers. The present invention further relates to an image formation apparatus using the optical scanner. More particularly, the present invention relates to an optical scanner suitable for a multi-color image formation apparatus for forming a color image by superposing toner images of a plurality of colors, and an image formation apparatus using the optical scanner.
2) Description of the Related Art
In image formation apparatuses using the Carlson process, formation of latent images, development of the latent images, and transfer of the developed latent images are carried out with rotation of photosensitive drums. For example, multi-color image formation apparatuses include a plurality of photosensitive drums arranged along a transport direction of sheet media onto which images are transferred, and image forming stations for respective colors forming toner images which are to be superposed onto each other. In these image formation apparatuses, differences in time from which the latent image is formed to which the latent image is transferred caused by eccentricity of the photosensitive drums and variation in the diameters of the photosensitive drums, differences in distances between the photosensitive drums, and variation in speed or meandering of transfer members such as transfer belts or conveyor belt which carries the sheet media are generated. As a result, toner images become out of registration and thus colors of the images formed become out of registration or color change is caused. Therefore, image quality is degraded.
Likewise, in optical scanners, which forms latent images on photosensitive drums, if positions at which latent images are formed on the photosensitive drums do not precisely match each other, colors of the images formed become out of registration or color change is caused when the differently colored images are superimposed.
These deviations have been corrected by regularly, for example job by job, detecting positions in a sub scanning direction of detection patterns recorded on transfer members, and adjusting timings at which writing is started, without considering whether the deviations are related to the optical scanners or means other than the optical scanner (see the Japanese Patent Publication No. 3049606, and the Japanese Patent Publication No. 3078830).
Heat generated by the polygon motor or the like causes temperature differences between scanning lenses for different colors in between the corrections, and thus the refracting power changes. Consequently, colors of the images generated become out of color registration due to the deviations in the sub scanning positions and to differences in magnification in the horizontal scanning direction.
Examples in which displacement of scan lines caused by a machining error or thermal deformation of the scanning lens, a deviation in the height of beams incident on the scanning lens, or so-called decentering is corrected have been disclosed. One of the examples in which the displacement is corrected by shifting the scanning lens having a power in the sub scanning direction along the main scanning direction is disclosed in the Japanese Patent Application Laid-open No. 2002-148551. Further, another example in which the optical axis of the scanning lens is shifted with respect to the light beams to correct the displacement is disclosed in the Japanese Patent Application Laid-open No. H11-64758). Moreover, an example of a method of correcting the displacement using means such as inclining the scanning lens on a plane orthogonal to the scanned plane is disclosed in the Japanese Patent Application Laid-open No. S64-52116. In these examples, the degrees of the displacement among jobs are detected, and corrected depending on the degrees detected.
The deviations are now typically seen as more and more scanning lenses are being made of plastic. To prevent the deviations, the imaging unit formed of a scanning lens, which is common to the respective color beams and does not have a converging power in the sub scanning direction, and scanning lenses for the respective color beams, is disclosed for example in the Japanese Patent Application Laid-open Nos. H2-250020 and H7-43627. According to the imaging unit, even if the refracting power changes, the change is commonly shared by the respective color beams. As a result, the colors of the images formed become less out of registration. Since a plurality of light beams corresponding to the respective colors are scanned together by the same surface of the polygon mirror, optical means for gathering the light beams from the light source units and direct the light beams to be incident on the polygon mirror is preferably required as disclosed in the Japanese Patent Application Laid-open Nos. 2001-296492 and H9-179047.
For the arrangement of an optical system before the deflector in the tandem-type image formation apparatus, there is a method of decreasing width occupied by all the light beams in the sub scanning direction by defining the distances between the light beams lined in the sub scanning direction. For example, light beams from a plurality of light sources are superposed on each other in the main scanning direction by a turning mirror such that the light beams can be regarded substantially as a single light beam, and guided to an optical deflector. The turning mirror is placed at a distance in the direction of optical axis between an optical element that condenses the respective the bundle of rays to be substantially linearly long in the main scanning direction on the reflecting surface of the optical deflector, and the optical deflector. Accordingly, by changing the sizes of the reflecting surfaces of the respective mirrors in accordance with the diameters of the bundles of rays in the sub scanning direction on the respective mirrors, and making the distances between the adjacent light beams different, the width occupied by all the light beams in the sub scanning direction is decreased as disclosed in for example the Japanese Patent Publication No. 32222052.
In the multi-color image formation apparatuses in which a plurality of image forming stations are arranged along the transfer direction of the transfer member to superpose colors, if the positions of the latent images transferred by the respective stations do not accurately match each other, colors of the image formed may become out of registration or color change may be caused.
In the optical scanners, however, even if the deviation in the scanning position between the respective stations, which causes the colors to be out of registration, is adjusted before each job, if the number of sheets to be printed in one job increases, since the incident position on the scanning lens varies due to the deformation of the housing resulting from the temperature change, the variation caused until the next correction cannot be prevented,
Naturally, printing can be suspended to perform the correction in the middle of a job, but it takes time to correct the curving of the scan lines, in addition to the write start positions in the main scanning direction and the sub scanning direction of the scan lines. Further, it is necessary to record the detection patterns for detecting the deviations on the transfer member to detect the result of the correction. In the meantime, the apparatus cannot be used for the recording, waiting time for printing increases, and thus the efficiency of operation is decreased. Further, if the number of corrections increases, wasteful consumption of the toner increases. Therefore frequent corrections should be avoided.
The scanning position is preferably maintained stable despite of any environmental changes. Some of the above examples in which the common scanning lens is used for the respective color beams are directed to achieve this object. However, according to these examples, the thickness of the polygon mirror for deflecting the beams together is thick. Consequently, the edges of the polygon mirror generate a greater windage that increases the load and the power consumption. Therefore, it is desired to make the polygon mirror thin, and thus it is required to decrease the distances between the respective color beams. It is also necessary to place the optical system including to the light source units and the deflection unit together with respect to the deflection position of the single polygon mirror. However, to avoid interferences between these units, it is required to locate the units away from the polygon mirror. Accordingly, the size of the optical scanner cannot be downsized. It is therefore an object in the art to arrange the light source units such that space is spaced as much as possible.
For decreasing the distances between the respective light beams, the reflective mirror surface of the optical deflector may be decreased according to the above example disclosed by the Japanese Patent Publication No. 32222052. Another example with separating optical means is also disclosed in the Japanese Patent Application Laid-open No. 2000-330049, which includes light source means having a plurality of light emission sources and guides the light beams that have been deflected to the corresponding surfaces to be scanned. However, to separate the deflected light beams so as to be guided to the different surfaces, it is necessary to provide a refracting power in the sub scanning direction of the scanning lens shared by all the light beams, to increase the differences between the adjacent light beams in the sub scanning direction. When the scanning lens shared by all the light beams has the refracting power in the sub scanning direction, the shape of the main scanning cross section changes along the sub scanning direction, and when the incident bundles of rays are displaced in the sub scanning direction, uniformity of the velocities is decreased. The imaging performance in the main scanning direction also deteriorated. Further, when a temperature distribution occurs in the lens due to the generation of heat in the optical deflector, and the shape of the lens changes due to a uniform temperature change, "out of color registration" occurs due to the decrease in the uniformity of the velocities among the respective light beams.

Optical scanner and image formation apparatus


An internal combustion engine including a cylinder, a crankshaft, a reciprocating piston disposed in the cylinder and operably coupled to said crankshaft, and a carburetor. The carburetor includes an airflow passage through which varying amounts of air flows; a variably positioned throttle valve located in the airflow passage, the amount of air flowing through the airflow passage being varied in response to the position of the throttle valve; a source of stored liquid fuel; a well containing liquid fuel and in independent fluid communication with the source of stored liquid fuel; a nozzle extending between the liquid fuel contained in the well and the airflow passage, the nozzle having an outlet located upstream of the throttle valve in the airflow passage, a variable amount of the liquid fuel contained in the well being conveyed through the nozzle to the airflow passage in response to the amount of air flowing through the airflow passage; and an idle circuit in independent fluid communication with both the source of stored liquid fuel and the well, the idle circuit containing liquid fuel and having at least one fuel outlet located in the airflow passage downstream of the throttle valve, a variable amount of the liquid fuel contained in the idle circuit being conveyed to the fuel outlet in response to the amount of air flowing through the airflow passage. The engine may also include a governor mechanism by which the throttle valve is positioned in response to the speed of the crankshaft.

1. Field of the Invention
The invention relates generally to engines, and in particular to small gasoline engines, such as those used in lawn and garden implements.
2. Background Art
In a prior naturally aspirated four-cycle engine, such as engine 20 shown in FIGS. 1-3, carburetor 22 is provided in which air flowing therethrough is charged with fuel. The admixture of fuel and air flows through intake manifold 24 to which the carburetor is attached, and into intake port 26 of cylinder head 28. The cylinder head or, in the case of an L-head engine (not shown), the cylinder block, is provided with at least two valves (not shown), one of which is an intake valve past which the fuel/air mixture flows as it is drawn from the head into cylinder 30 having reciprocating piston 32 therein. The other valve is an exhaust valve past which exhaust gases exit cylinder 30 after combustion of the fuel/air mixture. As the piston moves away from the head, the intake valve is opened and the admixture is drawn into the cylinder. The intake valve is then closed and piston moves toward the head, the valves of which are now both closed. The admixture is thus compressed and is then spark-ignited in the conventional way, the expanding combustion gases forcing the piston away from the head, powering the engine. As the piston again approaches the head, the exhaust valve is opened and the exhaust gases are forced from the cylinder. The cycle then repeats as the piston again moves away from the head.
The intake strokes of the piston in the cylinder provide a continuous source of vacuum which acts to draw air through carburetor 22. The amount of vacuum, however, varies with the speed of the engine, which in turn is regulated by the amount and/or quality of the fuel/air mixture delivered to the cylinder. Referring now to FIG. 4A, the airflow passage through carburetor 22 has venturi portion 34, and the amount and/or quality of the fuel/air mixture delivered to cylinder 30 is controlled through pivoting throttle plate or throttle valve 36 located in the airstream, downstream of venturi throat 38. The angular position of the throttle plate is controlled by rotation of its attached shaft 40 to vary the amount of air allowed through the carburetor, and thus the pressure of the air at or near the venturi throat and the amount of fuel delivered to that air through open end 42 of tubular main jet nozzle 44, during off-idle running conditions. Opposite end 46 of main jet nozzle 44 extends into main jet well 48, and fuel is metered into main jet well 48 from the carburetor""s fuel storage bowl 50 through metering jet passage 52 extending therebetween. The fuel in main jet well 48 provides a ready supply of fuel for main jet nozzle 44.
In its idle position, which is shown in FIG. 4A, throttle plate 36 is substantially closed, and only a small amount of air is allowed to be drawn through the carburetor; fuel is supplied to the airstream and is allowed to pass through carburetor 22 by means of idle circuit 54 having a fuel supply orifice located downstream of the throttle plate, or an axially arranged plurality of axially spaced fuel supply orifices 56, 58, 60 (as shown), at least one of which is located downstream of throttle plate 36. Fuel supply orifices 56, 58, 60 are sequentially exposed to low air pressure as throttle plate 36 opens from its substantially closed, idle position, to a slightly more open, off-idle position during acceleration from idle as shaft 40 is rotated. This xe2x80x9cprogressivexe2x80x9d system of idle fuel orifices is well known in the art, and is disclosed, for example, in U.S. Pat. No. 4,360,481 to Kaufman, the disclosure of which is expressly incorporated herein by reference. Idle fuel orifices 56, 58, 60 are provided in the wall surface of the carburetor""s air flow passage, and open into idle fuel chamber 62 which is supplied with liquid fuel by idle circuit 54. Notably, idle fuel outlets 56, 58, 60 may be located in a diverging portion of the carburetor""s venturi and airflow passage, the diverging portion serving as a diffuser which causes the pressure of the air flowing past the idle fuel supply orifice(s) to be increased. The flow of the liquid fuel through the idle circuit, and thus the idle speed of the engine, is controlled through an idle feed restrictor comprising screw 64 as shown.
It is to be noted that at least one of the idle fuel orifices (i.e, orifice 56, the xe2x80x9cprimaryxe2x80x9d fuel orifice) is at all times downstream of throttle plate 36. As the throttle plate is opened slightly during acceleration from idle, first progressive orifice 58 and second progressive orifice 60 sequentially become downstream of the opening throttle plate, and additional fuel/air emulsion is provided therethrough to aid in the engine""s smooth acceleration to an off-idle speed. Air is received within chamber 62 through idle air bleed orifice 66 located in the wall surface of the carburetor""s air flow passage, upstream of the throttle plate, and is mixed with liquid fuel in chamber 62 to produce therein an idle fuel/air emulsion which is delivered to the airstream through at least idle fuel supply orifice 56, and perhaps through orifices 58 and/or 60 as well. The admixed air and fuel is then delivered to cylinder 30 to support the idle running condition of the engine.
As the throttle is opened from its idle position, the pressure of the air flowing through venturi throat 38 drops with the increasing speed of air moving therethrough. A main fuel/air emulsion is thus drawn to venturi portion 34 at or near its throat 38 through main jet nozzle 44 to support the faster running condition of the engine. Because throttle plate 36 is now no longer substantially closed, a greater amount of air is allowed to pass through the carburetor; the pressure of the air flowing across the idle fuel outlets 56, 58, 60 is increased, and a lesser amount of fuel is provided to the airstream by idle circuit 54. At high engine running speeds, with throttle plate 36 substantially fully opened, the vacuum condition at or near venturi throat 38 is even greater, owing to the higher velocity of the air flowing therethrough; further, the air pressure at the idle fuel outlets 56, 58, 60 is even higher, and still less fuel is delivered to the airstream by idle circuit 54.
The idle circuit is typically one of two types relative to the main fuel circuit, the latter comprising main jet well 48 and main nozzle 44: (1) the idle circuit may be a separate circuit entirely which parallels the main circuit, with liquid fuel supplied from the carburetor""s fuel supply bowl 50 to the idle circuit and main jet well independently; or (2) as shown in FIG. 4A, idle circuit 54 may be xe2x80x9cmarriedxe2x80x9d to the main fuel circuit by having its supply passageway 68 in exclusive fluid communication with main jet well 48. Separate idle and main fuel circuits may lead to undesirable emissions during the transition from idle to off-idle running conditions, however, for the pressure of the air flowing across the idle fuel orifices 56, 58, 60 may still be low enough to draw fuel therefrom during the transition, causing the engine to temporarily run too rich; thus married systems are often preferred for reduced engine emissions.
In addition to its separated or married main and idle fuel circuits, some carburetors may utilize a third fuel circuit which also provides fuel to the airflow passage, at a location upstream of the throttle plate and intermediate the outlets of the main jet and the idle fuel circuit. This third fuel circuit may be referred to as a xe2x80x9csecondary fuel circuitxe2x80x9d, for it is secondary to the main fuel circuit from which it may be supplied with fuel. Published PCT International Application WO 98/55757, for example, discloses embodiments of carburetors having such secondary fuel circuits. With reference to FIGS. 1-4 of this PCT application, a first embodiment is disclosed having two such secondary fuel circuits. One of the two secondary fuel circuits (14) has a single fuel outlet (28F) which opens into the airflow passageway of the carburetor upstream of the throttle plate and idle fuel orifice(s); this secondary fuel circuit is in communication with the main fuel circuit and is provided with its air/fuel emulsion thereby. The other secondary fuel circuit (14A) has a spaced plurality of fuel outlets (28A, 28B, 28C, 28D) which also open into the airflow passageway upstream of the throttle plate and the idle fuel orifice(s); this secondary fuel circuit is also in communication with the main fuel circuit, from which it is supplied with an air/fuel emulsion. The fuel delivered to the airflow passageway through the secondary fuel circuit outlets (28A, 28B, 28C, 28D, 28F) is disclosed to be in a highly vaporized state, and the different locations of these outlets along the airflow passageway, where different airflow characteristics are anticipated, supposedly provide fuel delivery which is more responsive to changing airflow conditions vis-a-vis carburetors without such secondary fuel circuit(s).
The above-mentioned PCT application also discloses another embodiment of a carburetor having such a secondary fuel circuit. With reference to FIG. 5 of that application, the carburetor includes an idle circuit which is provided with fuel through an idle supply passage (105A). A secondary fuel delivery circuit (14B) receives an air/fuel emulsion from the main fuel circuit, and includes an intermediate circuit (105) having a single fuel delivery orifice (28F) which opens into the airflow passage intermediate the main and idle fuel outlets, upstream of the throttle plate. The intermediate fuel circuit (105) receives fuel from both the main fuel circuit, and from the idle circuit through an idle transfer passage (104) which interconnects the idle circuit and the secondary fuel delivery circuit.
The above-mentioned PCT application also discloses another embodiment of a carburetor having such a secondary fuel circuit. With reference to FIG. 6 of that application, the carburetor includes an idle fuel circuit and an intermediate fuel circuit (105) which are each provided with fuel through a supply passage (105A). A secondary fuel circuit (14C) provides an air/fuel emulsion obtained from the main fuel circuit to secondary fuel delivery outlet orifices (28B, 28F) which open into the carburetor""s airflow passageway upstream of the throttle plate.
Some engines, such as engine 20, include a mechanical, centrifugal flyweight governor mechanism, such as mechanism 70, best shown in FIGS. 2A and 3, which regulates engine speed. With reference to FIGS. 1-3, 5 and 6, engine 20 includes crankshaft 72 having an eccentric portion (not shown) which is operably coupled to reciprocating piston 32 in the well-known manner, as by a connecting rod. Crankshaft 72 is supported by, and extends through, bearing portions 74, 76 provided in joined crankcase portions 78, 80, respectively, which form the engine crankcase or housing. Within the engine crankcase, crankshaft 72 is provided with a gear (not shown) which is in meshed engagement with camshaft gear 82, which is rotatably fixed to a camshaft (not shown) of known type. The camshaft rotates at one half the speed of the crankshaft and controls the operation of the intake and exhaust valves in the manner well known in the art. Camshaft gear 82 is intermeshed with governor gear 84, which comprises part of governor mechanism 70. Disposed on governor gear 84, and adapted to rotate therewith, is flyweight assembly 86, best shown in FIGS. 5A and 5B, which comprises base 88 to which are pivotally attached a pair of opposed flyweights 90. Flyweights 90 are received in annular recess 92 of governor spool 94, which is slidably disposed on spool shaft 96, as best shown in FIGS. 6A and 6B. End 98 of spool shaft 96 extends through base 88 of the flyweight assembly and is fixed relative to the crankcase. Spool 94 moves axially, i.e., substantially vertically, on shaft 96 between shoulder 100 and snap ring 102 (FIG. 6A).
At higher engine speeds, spool 94 is moved upwards on shaft 96, toward snap ring 102, under the force of flyweights 90 which bear against a surface defining recess 92. The centers of mass of the flyweights pivot outwardly with the increasing rotational speed of governor gear 84, and the portions of the flyweights which are in contact with the spool force the spool upwards on shaft 96. At lower engine speed, spool 94 has a position closer to shoulder 100, the spool being biased by a spring into this generally downward position and overcoming the upward force attributed to the pivoting flyweights as described further hereinbelow.
As best shown in FIGS. 2 and 3, spool 94 has flat upper surface 104 on which free end 105 of governor rod 106 rests. Rod 106 is supported by bearing portion 108 of crankcase portion 78, through which it extends (FIG. 2), and between bearing portion 108 and spool surface 104, rod 106 is provided with a 90xc2x0 bend; upward travel of spool 94 along shaft 96 thus induces rotation, relative to the engine crankcase, of governor rod end 109, which protrudes through bearing portion 108. As best shown in FIGS. 1 and 2, lever 110 is rotatably fixed to end 109 of governor rod 106 via clip 112, such that the lever pivots about axis 114 as rod end 109 rotates in bearing portion 108. The orientation between lever 110 and clip 112 may be adjusted and fixed by means of screw 115 (FIG. 1).
Spring 116 is attached to and extends between end 118 of lever 110 and end 120 of pivoting throttle control member 122, the other end 124 of which, on the opposite side of pivot point 126, is moved by means of a conventional push-pull throttle cable (not shown) attached thereto and actuated by the operator. Tension on spring 116 biases lever 110, and thus end 109 of governor rod 106, in a counterclockwise direction about axis 114, as viewed in FIG. 1, thereby imparting a downward biasing force on spool surface 104 through abutting free end 105 of rod 106.
With reference to FIGS. 1-3 and 4A, wire link 128 is attached to and extends between end 118 of lever 110 and crank arm 130 of carburetor throttle plate shaft 40. The above-mentioned counterclockwise bias placed on lever 110 by spring 116 places link 128 in compression, urging throttle plate 36 into an open position. On startup, as the engine speed initially increases in response to this spring-induced bias, the rotation of flyweights 90 will force spool 94 to rise, thereby forcing lever 110 to rotate in a clockwise direction, as viewed in FIG. 1, about axis 114 against the force of spring 116 and move throttle plate 36 towards its closed position via link 128. It will be understood by those skilled in the art that under normal operating conditions, at any desired engine running speed set by the operator, the tension of spring 116 and the force exerted on spool 94 by the flyweights offset one another, and are continually adjusted to maintain the desired engine running speed, the governor opening or closing throttle plate 36 in response to lower or higher engine speeds, respectively, which respectively result from increased or lightened loads on the engine. Thus, the desired engine running speed, once set, is thereafter maintained at a substantially constant level as the governor appropriately opens the throttle in response to an increase in load on the engine to provide more power for accommodating the increased load. The increase in load, recognized by the governor as a decrease in engine speed, decreases the centrifugal force acting on the flyweights, and the spring pulls lever 110 counterclockwise, thereby opening the throttle. A decrease in load, recognized by the governor by an attendant increase in engine speed, increases the centrifugal force action on the flyweights, and the rising spool causes lever 110 to rotate clockwise against the force of spring 116, thereby closing throttle plate 36. Thus the speed of the governed engine is stabilized or maintained at the desired level despite load fluctuations.
As mentioned above, married idle and main fuel circuits are desirable for avoiding the emission concerns associated with separate circuits, but in engines having married fuel systems, governor mechanisms such as that described above may actually cause an unsteadiness of the engine speed during the transition from a high engine running speed condition to an idle condition or vice versa. Here, the vacuum on main jet nozzle 44 during high speed conditions may be so great that it places an undesirably high flow restriction on idle circuit fuel 54. This added restriction may be best understood by characterizing this added restriction as placing the liquid idle circuit fuel in xe2x80x9ctensionxe2x80x9d, such that it does not so readily flow to idle fuel outlets 56, 58, 60. Initially, when making the transition from high speed to idle, a too lean condition is experienced, causing the engine speed to reach abnormally low levels. Governor mechanism 70 perceives this reduction in engine speed as an increased load to be accommodated by opening the throttle. The engine speed consequently increases. There being little or no load, however, the governor mechanism reacts to this speed increase by closing the throttle. There again may be too much tension on the fuel in idle circuit 54 to readily achieve a smooth transition to a normal engine idle speed, and the cycle repeats, the governor causing the engine speed to oscillate as it seeks to achieve a stable running condition and thereby creating an undesirable xe2x80x9ctug of warxe2x80x9d condition on the idle fuel between the sources of vacuum located at the idle fuel outlets 56, 58, 60 and the main nozzle 44.
Referring again to FIG. 4A, idle circuit 54 comprises an interconnected series of conduits or bores 132, 134, 136 which extend between fuel chamber 62 and the idle circuit""s source of liquid fuel, passageway 68 which communicates with main jet well 48. Idle circuit restrictor screw 64 is threadedly received in a counterbore provided in cast body 138 coaxially with horizontal bore 134, which is fluidly intermediate substantially vertically extending bores 132 and 136. The opening at the bottom of lowermost vertical idle circuit bore 136 is plugged with ball 140 which seals the bore from fuel bowl 50. Cross bore 144 is provided. in cast body 138 and extends from the outer surface thereof, within bowl 50, through bore 136, and into main jet well 48, cross bore 144 partially forming idle circuit fuel supply passageway 68. Passageway 68 also includes orifice 146 provided through the wall of hollow bowl xe2x80x9cnutxe2x80x9d 148, orifice 146 being aligned with cross bore 144 and serving as a flow restrictor. Orifice 146 provides a flow restriction which may help reduce the severity of, but does not eliminate, the above-described tension condition on the fuel in idle circuit 54. The diameter of orifice 146 may be approximately 0.023 inch. A smaller such restriction may inhibit the ready flow of fuel from main jet well 48 to idle circuit 54. Main jet well 48 is partially defined by hollow, externally threaded bowl nut 148, which secures bowl 50 to cast body 138 of the carburetor, and liquid fuel is received into main jet well 48 through above-described metering jet 52, which extends through the bowl nut.
The opening of the portion of cross bore 144 which lies on the radial side of bore 136 opposite main jet well 48 is plugged with ball 152 which seals that portion of cross bore 144 from the gasoline in fuel bowl 50. The placement of ball 152 within cross bore 144, which is located well below surface level 153 of the liquid fuel in bowl 50, is best shown in FIG. 4B. Thus it can be readily seen that idle circuit 54 is xe2x80x9cmarriedxe2x80x9d to main jet well 48, and receives its fuel exclusively therefrom, via passageway 68.
As shown in FIG. 4A, main jet nozzle 44 is sealed in its bore 154 by o-rings 156 and 158 respectively located at the top and bottom thereof. Main jet nozzle bore 154 is provided with vent 160 which allows air to travel to the bottom, interior of the main jet nozzle through radial passage 162 therein. An emulsion of air and fuel proceeds upwardly through main jet nozzle 44 and is delivered near throat 38 of the venturi portion of the airflow passage during off-idle running conditions, where the main fuel/air emulsion is mixed with air flowing therethrough.
As described above, under high speed conditions, with a high vacuum placed on outlet end 42 of main jet nozzle 44, fuel in idle circuit 54 may be placed in tension. The flow of liquid idle circuit fuel being so additionally restricted, a ready supply of fuel to idle chamber 62 is prevented. The consequential lack of fuel flow to fuel chamber 62 results in a sharp decrease in engine speed during the transition to idle, which is perceived by the governor as an increased load to be accommodated by opening the throttle of the lightly loaded engine. The resulting high engine speed places a substantial vacuum on the main jet nozzle, which again places the idle circuit fuel in tension. Reacting to the overspeeding of the unloaded engine, the governor reacts by closing the throttle to its idle position, and the cycle repeats as the governor again seeks to achieve a stable running condition, an effort which is undermined by the tension being cyclically exerted on the idle circuit fuel by the vacuum on the main jet nozzle. This cycle manifests itself by an undesirable, automatic raising and lowering of the engine speed.
A way of addressing the problem by maintaining a smooth engine running condition during the transition from high speed to idle, while avoiding a too rich condition which can lead to emission concerns, and which may be easily incorporated into previous engine and/or carburetor designs, is highly desirable.
The present invention provides an increased flow of liquid fuel to the idle circuit and avoids the above-mentioned tension condition being placed on this fuel, which allows sufficient low-speed or idle fuel flow to the idle fuel orifice(s) to be maintained while providing sufficient high-speed or main fuel flow to the main jet well, thereby accommodating smooth transitions between high-speed and low-speed operations.
The present invention may be easily facilitated in existing engine and/or carburetor designs with little or no additional machining or tooling revisions and, unlike the above- mentioned carburetor disclosed in WO 98/55757, without providing any fuel delivery circuits which communicate with the airflow passageway other than the existing idle and main fuel circuits. Indeed, with regard to the particular embodiment of the present invention described herein, it will be appreciated that the present invention may be very readily implemented into the above-described engine (FIGS. 1-3) and/or carburetor (FIG. 4).
The present invention provides the solution to the above-mentioned problem by providing an internal combustion engine including a cylinder, a crankshaft, a reciprocating piston disposed in the cylinder and operably coupled to the crankshaft, and a carburetor. The carburetor includes an airflow passage through which varying amounts of air flows; a variably positioned throttle valve located in the airflow passage, the amount of air flowing through the airflow passage being varied in response to the position of the throttle valve; a source of stored liquid fuel; a well containing liquid fuel and in independent fluid communication with the source of stored liquid fuel; a nozzle extending between the liquid fuel contained in the well and the airflow passage, the nozzle having an outlet located upstream of the throttle valve in the airflow passage, a variable amount of the liquid fuel contained in the well being conveyed through the nozzle to the airflow passage in response to the amount of air flowing through the airflow passage; and an idle circuit in independent fluid communication with both the source of stored liquid fuel and the well, the idle circuit containing liquid fuel and having at least one fuel outlet located in the airflow passage downstream of the throttle valve, a variable amount of the liquid fuel contained in the idle circuit being conveyed to the fuel outlet in response to the amount of air flowing through the airflow passage.
The present invention also provides an internal combustion engine including a cylinder having a piston reciprocatively disposed therein, a crankshaft operably coupled to the piston, and a carburetor having an airflow passage extending therethrough which is in fluid communication with the cylinder. The carburetor has a variably positioned throttle valve located in the airflow passage, and the amount of air flowing through the airflow passage is varied in response to the position thereof The carburetor also includes a source of stored liquid fuel, a well containing liquid fuel and in fluid communication with the airflow passage at a location upstream of the throttle valve, and an idle circuit containing liquid fuel and in fluid communication with the airflow passage at a location downstream of the throttle valve. The well and the idle circuit are each in independent liquid communication with the source of liquid fuel and with each other.
The present invention also provides an internal combustion engine including a cylinder having a piston reciprocatively disposed therein, a crankshaft operably coupled to the piston, and a carburetor having an airflow passage extending therethrough which is in fluid communication with the cylinder. The carburetor has a variably positioned throttle valve located in the airflow passage, and the amount of air flowing through the airflow passage is varied in response to the position thereof. The carburetor also includes a source of stored liquid fuel, a well containing liquid fuel and in fluid communication with the airflow passage at a location upstream of the throttle valve, an idle circuit containing liquid fuel and in fluid communication with the airflow passage at a location downstream of the throttle valve, and means for providing the idle circuit with liquid fuel directly from the source of liquid fuel and with liquid fuel directly from the well in amounts which respectively vary with engine speed.
The present invention also provides a carburetor including an airflow passage through which varying amounts of air flows; a variably positioned throttle valve located in the airflow passage, the amount of air flowing through the airflow passage being varied in response to the position of the throttle valve; a source of stored liquid fuel; a well containing liquid fuel and in independent fluid communication with the source of stored liquid fuel; a nozzle extending between the liquid fuel contained in the well and the airflow passage, the nozzle having an outlet located upstream of the throttle valve in the airflow passage, a variable amount of the liquid fuel contained in the well being conveyed through the nozzle to the airflow passage in response to the amount of air flowing through the airflow passage; and an idle circuit in independent fluid communication with the source of stored liquid fuel and the well, the idle circuit containing liquid fuel and having at least one fuel outlet located in the airflow passage downstream of the throttle valve, a variable amount of the liquid fuel contained in the idle circuit being conveyed to the fuel outlet in response to the amount of air flowing through the airflow passage.
The present invention also provides a carburetor having an airflow passage extending therethrough, the carburetor including a variably positioned throttle valve located in the airflow passage, the amount of air flowing through the airflow passage being varied in response to the position of the throttle valve, a source of stored liquid fuel, a well containing liquid fuel and in fluid communication with the airflow passage at a location upstream of the throttle valve, and an idle circuit containing liquid fuel and in fluid communication with the airflow passage at allocation downstream of the throttle valve, the well and the idle circuit each being in independent liquid communication with the source of liquid fuel and with each other.
The present invention also provides a carburetor having an airflow passage extending therethrough, the carburetor including a variably positioned throttle valve located in the airflow passage, the amount of air flowing through the airflow passage being varied in response to the position of the throttle valve, a source of stored liquid fuel, a well containing liquid fuel and in fluid communication with the airflow passage at a location upstream of the throttle valve, an idle circuit containing liquid fuel and in fluid communication with the airflow passage at a location downstream of the throttle valve, and means for providing the idle circuit with liquid fuel directly from the source of liquid fuel and with liquid fuel directly from the well in amounts which respectively vary with the amount of air flowing through the airflow passage.

Engine having carburetor with bridge circuit


The invention features the generation of timing signals for use in the generation of a video signal. Vertical timing codes and horizontal timing codes are stored in a memory. The horizontal timing codes define regions of at least two types of horizontal timing signals of the video signal, and the vertical timing codes define the timing of the horizontal timing signals. The vertical and horizontal timing codes are stepped through to generate at least one signal indicative of the timing of the horizontal timing signals.

The invention relates to video timing generation.
As shown in FIG. 1, a video image is typically generated on a television screen 10 by projecting three electron beams (one for red, green, and blue) onto a phosphor coating on the back of the screen 10. Each electron beam traverses a predetermined pattern across the screen 10, and the time varying intensity of the electron beam (i.e., the number of electrons striking the phosphor coating) modulates the intensity of light emitted by the phosphor coating.
The predetermined pattern includes horizontal scan lines 12 with the first scan line 12 having an origin at a point 16 at the upper left corner of the screen 10. Each scan line 12 has a slight downward incline from the left to the right of the screen 10. Once the electron beam reaches the far right of the screen 10 (and current scan line 12), the electron beam traverses horizontal retrace lines 14 to move the electron beam back to the far left of the screen 10.
For noninterlaced video, once the electron beam reaches a point 18 at the bottom of the screen 10, the top-to-bottom scan, or field, and the video image, or frame, are complete. Each electron beam then returns to the point 16 via a vertical retrace line (not shown). For interlaced video, a frame is formed from multiple successive scans of the electron beam from the top of the screen 10 to the bottom, i.e., multiple fields are used.
A typical video signal typically has horizontal timing signals which contain image information for controlling the three electron beams. The type of horizontal timing signal appearing in the video signal is a function of a vertical timing of the video signal. As shown in FIG. 2, the video signal may be divided into three fundamental types of horizontal timing signals: a regular horizontal timing signal 35, a serration pulse signal 36, and an equalization pulse signal 37.
Within the regular horizontal timing signal 35 an active signal 32 (in an active region 31) contains the information for one scan line 12. The time-varying magnitude of the horizontal timing signals 35-37 indicate the black-and-white formation for the scan line 12. The minimum black-and-white level (a black level) of the horizontal signals 35-37 is equivalent to the color black, and the maximum black-and-white level of the horizontal signals 35-37 is equivalent to the color white. Thus, the minimum level of the active signal 32 is equal to the black level.
A synchronization level is the minimum voltage level of the horizontal timing signals 35-37 and cannot be seen on the screen 10. Thus, during a region 33 of the regular horizontal timing signal 35 associated with one of the vertical retrace lines 14, the horizontal timing signal 35 is equal to the synchronization level. The regular horizontal timing signal 35 also has a region 29 which contains a color burst signal 34. The color burst signal 34 is a reference signal used to extract color information from the active signal 32.
The serration 36 and equalization 37 pulse signals occur during video blanking (i.e., during times when no additional illumination of the screen 10 occurs), such as during the generation of the vertical retrace line. The serration 36 and equalization 37 pulse signals can be distinguished by the length of the regions 38 and 42, respectively, at which the signals are at the synchronization level.


A message exchange system for software components on different processors. A first component's attempt to load a write register with a message pointer (or a message itself) triggers a determination whether space exists in a shared memory queue. If so, the queue is updated by incrementing a message counter, writing the message/pointer into the queue where designated by a write pointer, and changing the write pointer to a next queue location. A second component's attempt to load the message/pointer from a read register triggers a determination whether there is at least one new message in the queue. If so, the queue is updated by decrementing the message counter, reading the message/pointer from the queue where designated by a read pointer, and changing the read pointer to point to a next queue location. The determinations and queue updates are performed atomically with respect to the software components.

Shared memory is usually employed when multiple processors exchange messages. That is, when a first processor (which we herein term "CPU") writes a message into the shared memory so that a second processor (which we herein term "COP") can then read the message from the shared memory. Maintaining the integrity of the messages thus exchanged requires that any updating of the content of the message be performed "atomically" with respect to the software threads of execution.
Multiple processor safe message queues are typically implemented using such shared memory, as well as with locks and asynchronous signaling. The messages are put in the shared memory, and then read and written only after certain precautions are taken. For instance, the reader or writer software thread that creates the message will acquire a multi processor safe lock (usually implemented using a "spin lock"). And, when necessary, it will also acquire a single processor multi thread safe lock (usually termed a mutual exclusion lock or "mutex").
FIGS. 1a-c are schematic block diagrams wherein FIG. 1a stylistically depicts the general hardware (HW) environment of interest and FIGS. 1b-c depict the regular software (SW) operations necessary in prior art schemes.
There are usually also a few "corner conditions" that need to be considered. For instance, one needs to deal with the special case when a read is attempted but the message queue is empty, and one also needs to deal with the special case when a write is attempted but the message queue is full. Asynchronous signaling is typically used to handle these conditions (e.g., signaling after the first write to an empty message queue to wake up a waiting reader thread). Such asynchronous signaling is usually implemented by one processor interrupting another, and then within an interrupt service routine (ISR) signaling with a semaphore to wake up the blocked thread.
Unfortunately, all of these locking and signaling mechanisms require significant software design and implementation effort and significant runtime overhead.
Let us consider an example based on a spin lock. If a first thread running on CPU (a first processor) has acquired the spin lock and is preempted by another thread on CPU (the first processor), and then a third thread on the COP (the second processor) tries to get the spin lock it will be blocked for a long time until the first threads becomes active again and then releases the spin lock. Spin locks are usually implemented as polling within a loop that runs forever until the condition is met. As can be appreciated, this scheme may result in a temporary priority inversion, wherein a very high priority task on COP is delayed because a lower priority thread on CPU has ownership which is preempted by an unrelated higher priority thread on CPU. This scheme can also easily cause significant wait time, wherein COP becomes essentially useless while waiting on a favorable polling result.
Which has ownership is preempted by an unrelated higher priority thread on CPU.
Similarly, the use of a mutex imposes another overhead. Some operating systems (OSes) and real time OSes (RTOSes) take a significant amount of time to acquire a mutex even when the resource it is protecting is available.
Accordingly, what is still needed is a more efficient system for multiple processors to exchanges messages. This system should preferably eliminate the need to employ software-based mechanisms such as the spin lock and the mutual exclusion lock (mutex).

Multi processor and multi thread safe message queue with hardware assistance


A housing for an air flow rate meter is embodied by two housing parts joined together by a detent connection, so that the assembly is reduced to a single operation, and screws and nuts are omitted. The housing for air flow rate meters is especially suitable for fuel injection systems of mixture-compressing internal combustion engines with externally supplied ignition, or air-compressing, self-igniting internal combustion engines.

The invention is based on a housing for an air flow rate meter to a mixture-compressing internal combustion engine with externally supplied ignition. A housing for an air flow rate meter is already known (German Offenlegungsschrift 31 03 170), which along with a second housing part in which a throttle device is disposed forms a throttle valve neck for mixture-compressing internal combustion engines with externally supplied ignition; the housing for the air flow rate meter is embodied as a Venturi nozzle. An air bypass line begins upstream of the Venturi nozzle and discharges into the narrowest cross section of the Venturi nozzle, and the air flow rate meter is disposed in that line. The mechanical coupling of the two housing parts in the prior art is typically in the form of a screw connection, as shown for instance in European Patent Application EP 00 96 842 Al. The use of screws and nuts represents considerable expenditure for material. Moreover, the various operations that are required result in a long assembly time, entailing high production costs.
During operation, the danger exists that the screw fastening will loosen unintentionally as a result of the dynamic strains in the form of vibration and impact originating in the engine; the functional capability of the air flow rate meter is impaired thereby. For instance, the engine power can be reduced quite considerably from infiltrated air that is aspirated through leaking portions of the connection between the two housing parts, these leaks being caused by loosening of the fastening screws.
To assure operational safety, other, cost intensive provisions such as spring rings, which adequately secure the screw fastening, are necessary.


There is disclosed a heterojunction bipolar transistor (HBT) which operates as either the emitter top mode performance or the collector top mode performance and also operates for low power dissipation due to lower ON voltages. A high gain, ultra-high speed semiconductor device is also disposed which includes a collector top type pnp HBT as a switching transistor and a lateral npn bipolar transistor as a current injection source, together with an integration method thereof which meets high density requirement with simple processes. The HBT is implemented with an InP substrate and a collector or emitter layer of p type In.sub.x Al.sub.1-x As lattice matched at least to the InP substrate, a base layer of n type In.sub.x Ga.sub.1-x As, a first spacer layer interposed between the base and collector and a second spacer layer between the base and emitter, both the spacer layers being made of p type In.sub.x Ga.sub.1-x As wherein by introducing of material which serves as an n impurity, the external base region is formed by the n type In.sub.x Ga.sub.1-x As and the resulting n type In.sub.x Al.sub.1-x As. There is further provided an I.sup.2 L circuit which comprises a HBT collector layer and a HBT emitter layer both of p type In.sub.x Al.sub.1-x As lattice matched to an InP substrate and a HBT base layer of n type In.sub.x Ga.sub.1-x As. By introduction of an n type impurity a HBT external base region is formed by the n type In.sub.x Ga.sub.1-x As and the resulting n type In.sub.x Al.sub.1-x As, together with a BT collector region and a BT emitter region of n type In.sub.x Al.sub.1-x As, wherein the BT base is common to the HBT collector and connected to a contact layer of p type In.sub.x Ga.sub.1-x As.

1. Field of the Invention
This invention relates to a heterojunction bipolar transistor and its integration method and its manufacturing method.
2. Description of the Prior Art
Heterojunction bipolar transistors (HBT) have attracted a great degree of attention as the next generation of very-high speed devices which enjoy large current driving capabilities and excellent high frequency characteristics. In his article "Heterojunction Bipolar Transistors and Integrated Circuits," Proc. IEEE., Vol. 70, P. 13, 1982, H. Kroemer reported that the collector top type of heterojunction bipolar transistors HBT with a collector on the top of the devices are more favorable than the conventional emitter top type heterojunction bipolar transistors HBT with an emitter on the top thereof, because the former provides ease of implementing of high gain and high speed Integrated Injection Logic (I.sup.2 L) reduction of the area of base collector junctions, highly reliable high frequency performance, ease of implementing of grounded-emitter circuits, and so forth.
Of the collector top type heterojunction bipolar transistors, heterojunction bipolar transistors with a symmetric structure where the collector is also made up of a wide-gap material in relation with the base are in greatest demand, because they are beneficial to the application of I.sup.2 L and Emitter Coupled Logic (ECL) circuits. This is especially due to the capability to execute not only collector top performance but also emitter top performance. A feature of I.sup.2 L gates that the need of an isolation region may be eliminated by reversing the roles of the emitter and the collector in the conventional npn bipolar transistor to permit use as emitter-ground circuit and commonly using a n.sup.+ type substrate and that fundamental gates may be implemented without resistors by using pnp bipolar transistors as a current injection source. I.sup.2 L gates are, therefore, thought to meet high density and low power consumption requirements. As a matter of fact, I.sup.2 L gates were proposed where the collector top type or symmetric structure npn heterojunction bipolar transistors (HBT) are used as switching transistors and lateral pnp bipolar transistors (BT) as a current injection source, in an attempt to develop high gain, high speed and easy-to-manufacture I.sup.2 L gate integrated circuits.
P. M. Asbeck et al. reported in their article "GaAlAs/GaAs Heterojunction Bipolar Transistor Device and IC Technology for High-Performance Analog and Microwave Applications," IEEE Trans. Microwave Theory Tech., Vol. 37, P. 2032, 1989, that ON voltages of the base-to-emitter diodes of AlGaAs/GaAs heterojunction bipolar transistors were 1.35 V and about 60% higher than those of Si bipolar transistors (about 0.8 V), causing the problem of an increase in power dissipation.
H. Kroemer pointed out in his report problems with integration of the conventional heterojunction bipolar transistors that element-to-element wirings are complex and the necessity of isolation regions between individual transistors hampers higher density integration.
A first prior art heterojunction bipolar transistor proposed by H. Kroemer was to implement heterojunction bipolar transistors with a symmetric structure. This sort of bipolar transistor was also reported by S. Tiwari et al. in "Symmetric-Gain, Zero-Offset, Self-Aligned, and Refractory-Contact Double HBT's," IEEE Electron Device Lett., Vol. 9, P. 417, 1987. FIG. 12 is a cross-sectional view of a first conventional symmetric structure NpN type heterojunction bipolar transistor device. Disposed on a semi-insulating GaAs substrate 21 is an epitaxial growth structure which consists of a first contact layer 22 of highly doped n type GaAs, a collector or emitter layer 23 of n type AlGaAs, a base layer 24 of highly doped p type GaAs, a collector or emitter layer 25 of n type AlGaAs and a second contact layer 26 of highly doped n type GaAs stacked sequentially on the named order.
To form a base electrode, a portion of the second contact layer 26 and a portion of the emitter or collector layer 25 which are located on an external base region are removed by a wet etching technology using a solution of sulfuric acid and hydrogen peroxide or the like or the dry etching technology using chlorine gas or the like. Be ion implantation step completes the setup of the external base region 24a. An interelement isolation region 27 and an interelement isolation 28 are defined by implanting boron and proton ions, respectively. The final step is to deposit a collector/emitter electrode 9a, the base electrode 9b and an emitter/collector electrode 9c.
A second heterojunction bipolar transistor as discussed hereinafter was proposed as a solution to the second problem in an attempt to lower the ON voltage of the base-to-emitter diode. FIG. 13 is an energy band diagram of the second prior art heterojunction bipolar transistor which is typically an NpN type heterojunction bipolar transistor of an InGaAs/InAlAs system disposed with lattice matching on an InP substrate. This device structure comprises a grading layer which helps in reducing the ON voltage of the base-to-emitter diode. The illustrated structure includes an emitter 133 of n type In.sub.x Al.sub.1-x As (x=0.52), a base 144 of p type In.sub.x Ga.sub.1-x As (x=0.53) and a collector 155 of n type In.sub.x Ga.sub.1-x As (x=0.53). Particularly, the grading layer 133a is disposed between the emitter 133 and the base 144, the composition of which varies continuously from n type In.sub.x Al.sub.1-x As (x=0.52) to n type In.sub.x Ga.sub.1-x As (x=0.53). It is evident from FIG. 7 which shows an energy band diagram, that a barrier V against carriers between the base 144 and the emitter 133 (i.e., electrons) becomes lower due to the presence of the grading layer 133a, so that the built-in voltage of the diode becomes smaller and the ON voltage becomes lower.
In the first prior art symmetric structure heterojunction bipolar transistor as depicted in FIG. 12, the difference between the ON voltage of the external base 24a and the emitter 23 and the ON voltage of the diode between the internal base 24 and the emitter would be as low as 0.3 V in view of the materials used therein. Therefore, the diode between the external base 24a and the emitter 23 would turn On at high collector current densities of over several 10.sup.4 A/cm.sup.2, thereby developing an abrupt drop in current gain.
To suppress Be diffusion during the step of high temperature annealing by which the crystalline statue is recovered after ion implantation, it is necessary to keep the Be doping concentration between 3 and 5.times.10.sup.18 /cm.sup.3. Should Be be doped at a higher concentration than the specified scope, Be would be diffused during the annealing step so that the n type AlGaAs 23 would turn into p type and the heterojunctions between the p type GaAs 24 and the n type AlGaAs 23 and 25 would be destroyed with the accompanying development of a homojunction between the n type AlGaAs and the p type AlGaAs with a lower efficiency of carrier injection. As a consequence, the first prior art heterojunction bipolar transistor can not sufficiently lower the base resistance as compared with the emitter top type so that it may not take full advantage of the excellent high frequency characteristics of the collector top type transistor.
As mentioned above, to make smaller the built-in voltage of the base-emitter junction, the second prior art heterojunction bipolar transistor has the grading layer the composition of which varies continuously from In.sub.x Al.sub.1-x As (x=0.53) to In.sub.x Ga.sub.1-x As (x=0.52). In essence, the manufacturing of such grading layer which matches in lattice with the InP substrate is very difficult.
To improve integration density, an I.sup.2 L gate was proposed which uses a heterojunction bipolar transistor, in an article "Double Heterojunction GaAs/GaAlAs I.sup.2 L Inverter," by P. Narozy et al, Electron. Lett., Vol. 21, P. 328, 1985. FIGS. 14(A) and 14(B) show an equivalent circuit diagram and a cross sectional view of the I.sup.2 L gate device reported therein, respectively. There is disposed an epitaxial layered structure on a semi-insulating GaAs substrate 111, which structure consists of a first contact layer 112 of highly doped n type GaAs, an emitter layer 113 of n type AlGaAs, a base layer 114 of highly doped p type GaAs, a collector layer 115 of n type GaAs and a second contact layer 116 of highly doped n type GaAs, sequentially deposited in the named order. To form a collector mesa structure, the second contact layer 116 and the collector layer 115 are removed partially for a buildup of an external base region by the wet etching technology using a solution of sulfuric acid and hydrogen peroxide or the like or the dry etching technology using chlorine gas or the like. The subsequent Be ion implantation and thermal treatment for recovery of crystalline state result in buildup of the external base region of an npn heterojunction bipolar transistor and buildup of a collector region 114a or an emitter region 114b of a lateral pnp bipolar transistor. After formation of a base mesa structure through the use of the same etching technology as mentioned above, a base electrode of the heterojunction bipolar transistor or a collector electrode 110a of the lateral bipolar transistor, an emitter electrode of the heterojunction bipolar transistor or a base electrode 110b of the lateral bipolar transistor, an emitter electrode 110c of the lateral bipolar transistor and a collector electrode 110d of the heterojunction bipolar transistor are deposited, respectively. Measurements at high collector current densities revealed that the external base-emitter diode turned ON in the above mentioned materials at high collector current densities over several 10.sup.4 A/cm.sup.2, causing a sharp drop in current gain, because the difference between the ON voltage of the external base-emitter diode and the ON voltage of the intrinsic base-emitter diode was as low as 0.2 V-0.3 V in the collector top type npn heterojunction bipolar transistor used in the prior art I.sup.2 L gate device. As discussed above, to suppress Be diffusion during the step of high temperature annealing by which the crystalline state is recovered after ion implantation, it is necessary to keep the Be dopings between 3 and 5.times.10.sup.18 /cm.sup.3. As a consequence, the prior art collector top type heterojunction bipolar transistor can not sufficiently lower the base resistance as compared with the emitter top type so that it may not take full advantage of the excellent high frequency characteristics of the collector top type transistor. The hole mobility of the AlGaAs layer which forms the base of the lateral pnp bipolar transistor is as low as 100 cm.sup.2 /V sec and the diffusion length of the minority carriers is as low as about 0.5 .mu.m. To assume sufficient current gain, the thickness of the base needs to be less than 0.1 .mu.m. The profile of the p type AlGaAs intervening between the collector and emitter regions of the n type AlGaAs corresponds to the thickness of the base and needs to be less than about 0.1 .mu.m. Such requirement is difficult to meet even when the state-of-art technology is utilized.

Heterojunction bipolar transistor and its integration method

Matsushita Electric Industrial Co., Ltd.


A new pharmaceutical composition is disclosed that comprises clioquinol, vitamin B.sub.12, and, optionally, pharmaceutical acceptable carriers and/or excipients. The use of the pharmaceutical composition removes or alleviates the side effects of clioquinol.

2.1. ALZHEIMER'S DISEASE
Alzheimer's disease, which is the single major cause of dementia in adults in industrialized societies, is a degenerative brain disorder characterized clinically by a progressive loss of memory, confusion, dementia and ultimately death. Histopathologically, Alzheimer's disease is characterized by the presence in the neocortex, especially the hippocampus, of two brain lesions: the neurofibrillary tangles (NFTs) of paired helical filaments (PHF) in the neurons and the neuritic (senile) plaques in the extracellular space. The formation of senile plaques is related to the appearance of the symptoms and signs of the disease, including amnesia. After the formation of senile plaques, neurofibrillary tangles are produced in the neuronal bodies. The formation of neurofibrillary tangles is related to the worsening of amnesia and other symptoms of dementia.
There are several animal models of Alzheimer's disease. In one model, the insertion and overexpression in mice of a mutant form of the human amyloid precursor protein gene as a minigene under the regulation of the platelet-derived growth factor .beta. receptor promoter element causes the appearance of a syntaptic pathology and amyloid-.beta. peptide deposition in the brain of the mice. These changes in the brains of transgenic animals are similar to those seen in human Alzheimer's disease (Games et al., 1995, Nature 373:523-527).
In a similar model, transgenic mice were generated by using a promoter derived from the mouse neurofilament-light gene to drive expression in nerve cells of the mouse 42-amino acid A.beta. protein (LaFerla et al., 1995, Nat. Genet. 9:41-47). Such mice also exhibit insoluble A.beta. deposition in the brain.
A major component of the amyloid deposits in Alzheimer's disease is a polypeptide referred to herein as A.beta. (Amyloid-beta). A.beta. also accumulates in the wall and the lumen of the brain vessels. A.beta. is normally a soluble component of the cerebrospinal fluid where it is found in concentrations of about 3-5 nM. A.beta. may have 39 to 43 amino acids, typically 40 amino acids, in the mature form and is derived as a proteolytic cleavage product from a cell surface protein called the amyloid precursor protein (APP) (Kang et al., 1987, Nature 325:733-736). The normal function of A.beta. is not known at present but might be to form cation selective channels across cell membranes (Kawahara et al., 1997, Biophysical Journal 73/1, 67-75).
The major form of Alzheimer's disease is sporadic and has a late onset, whereas a small percentage of cases are familial and have an early onset. Some of the familial cases of Alzheimer's disease are strongly associated with one or more mutations at different sites on the A.beta. precursor protein, the gene of which lies on chromosome 21. Whether these mutations are the cause of Alzheimer's disease in the affected patients, however, has not been proven experimentally.
The plaques are not unique to Alzheimer's disease. The senile plaques are also seen in Down syndrome and in both aged human and animal brains. The numbers of plaques in non-demented aged humans are sometimes similar to those seen in Alzheimer's disease cases (Katzman et al., 1988, Ann. Neurol. 23:138-144).
The precipitation of synthetic A.beta. has been shown to be caused by several environmental factors including low pH, high salt concentrations and the presence of metals, e.g., zinc, copper, and mercury (Bush et al., 1995, Science 268:1921-1923). It has been reported that A.beta. itself specifically and saturably binds zinc with a high affinity binding (K.sub.D =107 nM) at a molar ratio of 1:1 (zinc: A.beta.) (Bush et al., 1994, J. Biol. Chem. 269:12152-12158). This binding takes place at physiological concentrations of zinc (Bush et al., 1994, Science 265:1464-1467).
There is a strong supposition that the removal of amyloid deposits from patients suffering from Alzheimer's disease will alleviate the symptoms of Alzheimer's disease. Therefore, several attempts have been made to prepare a drug for the removal of amyloid deposits, as methods for healing Alzheimer's disease are urgently sought.
International Publication No. WO 93/10459, dated May 27, 1993, discloses a method for the treatment of Alzheimer's disease by administering a zinc binding agent. As preferred compounds, phytic acid, desferri-oximine, sodium citrate, EDTA, 1,2-diethyl-3-hydroxy-pyridin-4-one, and 1-hydroxyethyl-3-hydroxy-2-methyl-pyridin-4-one are mentioned.
German publication DE 39 32 338, dated Apr. 11, 1991, discloses the use of an aluminum chelator, such as 8-hydroxy-quinoline, for the treatment of Alzheimer's disease.
U.S. Pat. No. 5,373,021, dated Dec. 13, 1994, discloses disulfiram and its salts and analogs. According to this patent, disclosed compounds may be used to reduce neurological damage caused by Alzheimer's disease.
The hitherto known compounds suggested for the treatment of Alzheimer's disease have several drawbacks, which has prevented their widespread use. Most of the compounds are unable to penetrate the blood-brain-barrier and thus cannot readily reach the areas in which the amyloid is deposited. Disulfiram, which may penetrate the blood-brain-barrier, has the drawback that when it is combined by a patient with ethyl alcohol, it causes severe adverse reactions, including headaches, nausea, vomiting, sweating, thirst, weakness, and low blood pressure.
The most extensively studied chelator is EDTA. However, the chelating effect of EDTA is relatively weak towards zinc and copper. Furthermore, EDTA cannot penetrate the blood-brain-barrier and is considered relatively toxic.

Clioquinol for the treatment of Alzheimer's disease


An electronic device, according to various embodiments, comprises: one or more image sensors; a first processor electrically connected to at least one of the one or more sensors via a first interface and including a first functional processing circuit and a second functional processing circuit capable of processing first output information of the first functional processing circuit; a second processor electrically connected to at least one of the one or more image sensors via a second interface; a third interface for connecting the first functional processing circuit and the second processor to transfer the first output information of the first functional processing circuit to the second processor; and a fourth interface for connecting the second functional processing circuit and the second processor to transfer second output information of the second processor to the second functional processing circuit. Various other embodiments are possible.

An electronic device can perform various functions in a complex manner. For example, a mobile communication terminal, a personal digital assistant (PDA), an electronic notebook, a smart phone, a tablet personal computer (PC), and the like have been developed to provide more convenience to users while realizing advanced performance.
The electronic device may include a plurality of processors to provide various functions. For example, the electronic device may include a plurality of processors configured to perform predetermined functional processing using sensing information acquired through a sensor.

Interface connected to image sensor and electronic device comprising interfaces connected among plurality of processors


Methods and systems for producing direct reduced iron (DRI), comprising: generating a syngas stream in a carbon dioxide (CO2) and steam reformer; and providing the syngas stream to a direct reduction (DR) shaft furnace as a reducing gas stream. The methods and systems also comprise combining the syngas stream with a recycled off-gas stream from the DR shaft furnace to form the reducing gas stream. The methods and systems further comprise removing carbon dioxide (CO2) from the recycled off-gas stream from the DR shaft furnace prior to combining it with the syngas stream to form the reducing gas stream. The methods and systems still further comprise feeding CO2 removed from the recycled off-gas stream from the DR shaft furnace to the CO2 and steam reformer. The methods and systems still further comprise feeding recycled off-gas from the recycled off-gas stream from the DR shaft furnace to the CO2 and steam reformer.

U.S. Pat. No. 3,844,766 (BEGGS, PROCESS FOR REDUCING IRON OXIDE TO METALLIC SPONGE IRON WITH LIQUID OR SOLID FUELS) provides an economical process for the direct reduction (DR) of iron ore by the efficient production of a reducing gas when the external source of fuel used in the process is a liquid or solid. A gasifier facility converts a minimal amount of fuel to a gas comprised principally of reductants which is supplemented with reductants reclaimed from the reacted off-gas produced in the reduction process. A controlled amount of water vapor is added to the gas mixture which is heated to approximately reduction furnace temperature before undergoing a shift reaction to equilibrium externally of the furnace to produce a reducing gas having a preferred gas composition.
It is preferable, however, that this process may be modified somewhat, with a CO2 and steam reformer replacing the gasifier and being fed by recovered CO2. Such CO2 and steam reformers are well known to those of ordinary skill in the art, but such use in a DR process is not.

Methods and systems for producing direct reduced iron incorporating a carbon dioxide and steam reformer fed by recovered carbon dioxide


An endoscope spectral image system is provided and includes: an image recording apparatus for recording a color image provided by using a scope; and a processor apparatus, in which spectroscopic characteristic information including a spectroscopic characteristic of CCD is output from the processor apparatus to the image recording apparatus along with color image data. At the image recording apparatus, matrix data in correspondence with the spectroscopic characteristic information is selected to be read from a plurality of matrix data stored in a memory, matrix operation by the matrix data and color image data is carried out at a spectral image-forming circuit, and a spectral image formed by signals of arbitrarily selected wavelength regions is provided.

In recent years, in an electronic endoscope apparatus using a solid state image sensor, attention is attracted to spectroscopic imaging combined with a narrow band pass filter, that is, a narrow band filter incorporated electronic endoscope apparatus (Narrow Band Imaging-NBI) based on a prediction of a spectroscopic reflectance in the digesting organ (stomach mucosa or the like). According to the apparatus, three band pass filters of narrow (wavelength) bands are provided in place of a rotating filter of R (red), G (green), B (blue) of a face sequential type, and a spectral image is formed by successively outputting illuminating light by way of the narrow band path filters and processing three signals provided by the illuminating light while changing respective weights thereof similar to a case of R, G, B (RGB) signals. According to the spectral image, in the digesting organ of the stomach, the large intestine or the like, a fine structure which cannot be provided in a background art is extracted.
Meanwhile, it has been proposed to form a spectral image by operation processing based on the image signal provided by white light not by the face sequential type using the narrow band pass filters but by a simultaneous type for arranging a color filter of a small mosaic to a solid state image sensor as shown by JP-A-2003-93336 and Tokyo University Printing Association Foundation 'Analysis and Evaluation of Digital Color Image' by MIYAKE, yoichi (P148 through P153). According thereto, a relationship between respective color sensitivity characteristics of RGB which are formed into numerical value data and a spectroscopic characteristic of a specific narrow band pass filter which is formed into numerical value data is calculated as matrix data (coefficient set) and by operation of the matrix data and RGB signals, a spectral image signal provided by way of the narrow band pass filter is pseudonically provided. When the spectral image is formed by such an operation, it is not necessary to prepare a plurality of filters in correspondence with a desired band pass region, an interchanging arrangement thereof is dispensed with and therefore, large-sized formation of the apparatus is avoided and low cost formation thereof can be achieved.
Meanwhile, according to a spectral image extracting a specific fine structure or the like of an object, it is necessary to select a preferable wavelength region or adjusting the selected wavelength region and there is a case in which a necessary and sufficient spectral image cannot be provided in inspection by an endoscope in a limited time period. Further, it is necessary to observe and diagnose the spectral image in details by comparing with a normal color image and when a spectral image having an arbitrary wavelength region can be formed and displayed after inspection by the endoscope, an apparatus having an excellent way of use can be provided.
Further, in the operation processing of the spectral image by the endoscope apparatus, for example, color image signals of RGB constituting a basis thereof differs by a spectroscopic sensitivity characteristic including a kind of a color filter of an imaging element (solid state image sensor or the like), a kind of a light source, a spectroscopic sensitivity characteristic of an optical system member of the endoscope of a light guide or the like to pose a problem that such differences in the spectroscopic characteristics of the endoscope of the light source effect an influence on reproducibility on the same wavelength region. That is, there are CCDs constituting solid state image sensors of a complementally color type having color filters of Mg, Ye, Cy, G and a primary color type having color filters of RGB, further, even in the CCD of the same kind, the spectroscopic sensitivity characteristic differs by an individual difference. FIG. 9 shows an example of spectroscopic sensitivity characteristics of color filters of primary color type CCD, respective spectroscopic sensitivities of the R, G, B color filters differ by an individual difference of CCD, in an operation processing using a single matrix data, the difference in the spectroscopic characteristics is reflected to an operation result and the spectral image having reproducibility cannot be provided.
Further, a spectroscopic characteristic of illuminating light differs by an aperture amount of a diaphragm blade in the light source apparatus owing to chromatic aberration of lenses, there is constituted a characteristic in which the more the light amount is reduced, the more the red color component is gradually cut from a long wavelength side to pose a problem that the reproducibility of the spectral image is deteriorated even by the spectroscopic characteristic of the illuminating light.

Endoscope spectral image system apparatus


A process for the preparation of polymers comprising: polymerizing at least one monomer of the formula X--CH.sub.2 --Ar--CH.sub.2 --X' in the presence of a base and at least one chain end controlling additive of the formula R--H to form a soluble conjugated poly(arylene vinylene) of the formula EQU R--CH.sub.2 --AR--CH.dbd.CH--!.sub.n --Ar--CH.sub.2 --R. where X and X' are electron withdrawing groups, R--H is a compound containing at least one acidic proton, R is a nucleophile, Ar is an aryl or aromatic group with from 5 to 30 carbon atoms, and n represents the number of repeating segments.

The present invention relates to electroluminescent polymer compositions and processes for the preparation and use thereof in, for example, electroluminescent devices such as electroluminescent displays and electrochemical cells.
More particularly, the invention relates to polymer compositions and to processes for making and using in, for example, high performance, that is, high stability and high luminosity electroluminescent displays and devices.
The present invention, in embodiments, is directed to processes for preparing soluble poly(p-arylene vinylene) polymers, especially poly(p-phenylene vinylene) polymers, wherein at least one solubilizing side chain or substitutent is present in the monomer imparts desirable solubility and processibility properties to the resulting polymer product. The present invention is also directed toward polymerization processes for controlling the molecular weight of the polymers, the functionality on the polymer chain ends, and polymer architecture using chain end controlling additives, which controlled factors contribute to improved stability and performance of light emitting devices constructed therefrom. By adjusting the ratio of a chain end controlling additive to a monomer, it is possible to control the molecular weights of the polymer. The higher the ratio, the lower the molecular weight of the polymer product. In extreme cases, one can prepare oligomeric phenylene vinylenes by using large amount of chain initiating additive(s). The use of chain end controlling additives provides a simple and general method for preparing poly(p-phenylene vinylene) polymers with specific chain end functionality. The chain end controlling additives generally serve to initiate and terminate polymerization and are incorporated in the polymer structure ultimately becoming bound at the ends of the polymer chain. The use of a chain end controlling additives with two or more polymerization initiation and termination site enables the preparation of block, branched, and grafted poly(p-phenylene vinylenes). Highly stable poly(p-phenylene vinylene) light emitting devices can be achieved by controlling the polymer molecular weights, chain ends, and architectures through chain end controlling additives.

Electroluminescent polymer compositions and processes thereof


A surgical cutting instrument is disclosed for percutaneously debulking tissue through an access sheath commonly used in minimally invasive laparoscopic or endoscopic surgical procedures. The cutting instrument includes a inner rotary member tube having a cutting edge at the distal end thereof for cutting and slicing tissue. The distal end of the cutting member tube extends from the distal end of a stationary sheath which prevents tissue from wrapping around the inner cutting member tube. The inner cutting member tube includes a hollow passageway for suctioning and aspirating tissue and fluid through the tube and into a collection chamber or out through a vacuum or suction line attached thereto. The instrument further includes an outer safety shield having a rounded distal end for preventing the puncture of a surgical tissue bag or from unintentionally cutting tissue by the attending physician. The outer shield has a channel across the distal end through the hollow passageway therein for feeding tissue into the cutting edge and controlling the vacuum applied to the tissue. Vacuum or suction control ports are included at the proximal end of the inner cutting member tube and stationary sheath for also controlling the amount of vacuum or suction applied to the tissue. The surgical cutting instrument includes a control handle for grasping by the physician. A removable collection chamber is connected to a coupler connected to the stationary sheath for collecting tissue therein. The inner cutting member tube extends through the collection chamber to a drive motor or to a remotely positioned rotary drive mechanism. A vacuum line is attached to the collection chamber for drawing tissue and fluid through the inner cutting member tube and into the collection chamber.

One of the major problems associated with minimally invasive surgery is percutaneously debulking or reducing a large tissue volume such as with a cyst, tumor, or an organ for removal through an access sheath. A number of power-driven, surgical cutting instruments are presently available in which a side port or a partial opening at the distal end of a cutting tube are rotated to shear and aspirate bone and cartilage through a lumen of the instrument. These side ports or partially open-ended cutting instruments are inefficient in debulking large volumes of soft- tissue due to their limited access cutting surfaces, which require an angled or a side approach for cutting. Furthermore, these side port or partially open-ended instruments cannot core soft tissue. This significantly increases the time necessary to debulk and remove tissue through an access sheath. This is particularly applicable in laparoscopic or pelviscopic procedures in which large fibroid cysts must be removed. These power-driven side port or partially open-ended instruments are best suited for cutting cartilage or bone material in arthroscopic procedures, but are very inefficient in debulking and removing large volumes of soft tissue.
Another side port cutting instrument is manually operated and uses a series of opposing jaws that are opened and closed to grasp and shear the tissue. Such a manually-operated device is extremely limited in debulking tissue because of the time required for grasping and cutting each piece of the large tissue volume.
Another problem associated with these side port or partially open-ended instruments are the complex angles that are required for the cutting edges. Not only do these complex cutting angle instruments have limited access, but also provide limited control or directionality with respect to slicing or cutting soft tissue.

Vance Products Incorporated D/B/A Cook Urological Incorporated


The invention relates to a device for supporting sheet-like materials for at least one separating process in the sheet-like materials, with at least one jet cutter device which may be displaced in the Y-direction during a separation process, with a first and second support surface together forming a support table for supporting the sheet-like material and with a jet trapping device, arranged between the first and second support surfaces and provided to be able to be displaced in the X-direction. The first and the second support surfaces are made from a flexible material forming part of at least one enclosed chamber, filled with a gas under pressure.

JP 4-91884 discloses a laser processing machine which comprises a device for supporting plate-like materials for at least one separating process in the plate-like material. The plate-like material is processed by a cutting beam arrangement. The plate-like material rests on a supporting table which comprises a first and a second supporting surface, between which a beam-catching device is provided. A cutting beam discharging downward during the processing of the plate-like material is received by the beam-catching device, such that the band-shaped material which is used for forming the first and the second supporting surface is not damaged. In this device, a housing is moved relative to fixed deflection axes of the band-shaped material via an electric motor, as a result of which the supporting surfaces are variable in size, such that the entire region of the plate-like material is available for processing by the cutting beam arrangement, and the beam-catching device is positioned below a cutting head of the cutting beam arrangement.
This device is designed for small and light sizes of the plate-like material. In addition, tilting or impairment of the position of the plate-like material may occur on account of a deflection of the band-shaped supporting surface.
JP 2000-153427 has disclosed a laser processing machine which has a device for supporting plate-like materials for at least one separating process in the plate-like material, in which device the first and the second supporting surface are formed by tubes which are arranged in parallel next to one another and are connected at their respective outer sides to a chain. Although such a device permits stiffening of the supporting surface, as viewed in the longitudinal axis of the tubes, for supporting heavy workpieces of large area, there is likewise the disadvantage that, in the traverse direction of a beam-catching device arranged between the supporting surfaces, a deflection of the supporting surface may occur. As a result, the processing point may be adversely affected.
Furthermore, WO 03/016004 A1 discloses a device for mounting planar material for at least one separating process in the plate-like material by means of a cutting beam arrangement. This device has a chain link belt which is carried by telescopic arms which determine the size of the first and the second supporting surface as a function of their stroke movement. Due to the configuration of horizontally extending telescopic arms, this device is restricted in the maximum load bearing capacity and in the size of the supporting surface. In addition, an arrangement and incorporation of a beam-catching device is not provided.
The devices according to JP 2000-153427 and WO 03/016004 A1 both have the disadvantage that the supporting surface is not completely closed due to the formation of chain links. As a result, there is the risk of good parts and remnants becoming caught on the supporting surface.

Device for supporting plate-like materials for at least one separating process


A steel cord for rubber reinforcement comprises a first group of core filaments (105) having a number of m and a second group of sheath filaments (110) having a number of n, m is three or four, the core filaments (105) are forming a helix, the core filaments (105) are not twisted together and being substantially parallel or the core filaments (105) have a twist pitch being more than 300 mm; the second group and the first group are twisted with each other, and the sheath filaments (110) are forming a flattened helix in the same direction of the helix of the core filaments (105), and the sheath filaments (110) have a cord twist pitch, at any cross-section of the steel cord, at least one interstice between two adjacent core filaments (105) is present. The steel cord has improved abrasion resistance and can contribute to the reduction of the weight of the tire.

To reduce the pollution to the environment, the environmental friendly tire is now desired. One direction is developing lighter weight tire. One of the solutions is reducing the rubber amount of the belt layer of the tire: The thickness of the belt layer is reduced and the weight of the tire is reduced. However, this will make the adjacent belt layers being easily separated, and will lead to the failure of the tire. Another solution is reducing the weight of the steel cords in the tire: The tire reinforced by the lighter steel cord becomes lighter.
Steel cord for reinforcing a rubber product, for example a tire, is always required to have good and even full rubber penetration.
To achieve the above requirements, an m+n flat cord has been developed.
EP2689939 discloses a steel cord with a structure of 2+n, wherein the two core filaments are contacting with each other, and n sheath filament are twisted with the two core filaments, and the core filament has a diameter bigger than the sheath filament.
JP2007063706 discloses a steel cord with a structure of 2+n, n is 1 to 3, wherein the two core filaments are contacting with each other, and n sheath filament are twisted with the two core filaments.
U.S. Pat. No. 6,748,731 discloses a steel cord with a structure of m+n, wherein the core filaments are arranged in side-by-side configuration and no voids are formed between the core filaments.
The steel cords of the above prior arts can help to reduce the weight of the tire and improve the rubber penetration property. However, new solution of steel cord for reducing the tire weight is still desired.

M+N steel cord for reinforcing rubber product