An invention is disclosed for reducing power in a CAM using sample words. A sample section of stored data is compared to a corresponding sample section of search data. If the sample section of the stored data is different from the corresponding section of the search data, a non-match result is generated. However, if the sample section of the stored data is equivalent to the corresponding sample section of the search data, the remaining section of the stored data is compared to a corresponding remaining section of the search data. Thus, the remaining section of the stored data is not compared to the corresponding remaining section of the search data if the sample section of the stored data is different from the corresponding section of the search data.

1. Field of the Invention
This invention relates generally to memory circuits, and more specifically to low power search techniques in content addressable memory circuits using sample search words.
2. Description of the Related Art
A content addressable memory (CAM) semiconductor device is a device that allows the entire contents of the memory to be searched and matched instead of having to specify one or more particular memory locations in order to retrieve data from the memory. Thus, a CAM may be used to accelerate any application requiring fast searches of a database, list, or pattern, such as in database machines, image or voice recognition, or computer and communication networks.
CAMs provide performance advantages over conventional memory devices having conventional memory search algorithms, such as binary or tree-based searches, by comparing the desired search term, or comparand, against the entire list of entries simultaneously, giving an order-of-magnitude reduction in the search time. For example, a binary search through a non-CAM based database of 1000 entries may take ten separate search operations whereas a CAM device with 1000 entries may be searched in a single operation, resulting in significant time and processing savings. Internet routers often include a CAM for searching the address of specified data, allowing the routers to perform fast address searches to facilitate more efficient communication between computer systems over computer networks.
Conventional CAMs typically include a two-dimensional row and column content addressable memory core array of cells. In such an array, each row typically contains an address, pointer, or bit pattern entry. In this configuration, a CAM may perform xe2x80x9creadxe2x80x9d and xe2x80x9cwritexe2x80x9d operations at specific addresses as is done in conventional random access memories (RAMs). However, unlike RAMs, data xe2x80x9csearchxe2x80x9d operations that simultaneously compare a bit pattern of data against an entire list (i.e., column) of pre-stored entries (i.e., rows) can be performed.
FIG. 1A shows a simplified block diagram of a conventional CAM 100. The CAM 100 includes a data bus 102 for communicating data, an instruction bus 104 for transmitting instructions associated with an operation to be performed, and an output bus 106 for outputting a result of the operation. For example, in a search operation, the CAM 100 may output a result in the form of an address, pointer, or bit pattern corresponding to an entry that matches the input data.
As mentioned above, to perform a search operation a CAM includes a plurality of bit pattern entries, each comprising a series of CAM cells coupled to a local match line. FIG. 1B is a schematic diagram showing a prior art bit pattern entry 120 in a conventional CAM. The bit pattern entry 120 includes a plurality of CAM cells 122 coupled to a local match line 124. In addition, the bit pattern entry 120 includes a current generator 126 and precharge circuitry 128 coupled to the local match line 124. The local match line 124 is further coupled to an inverter 130, which is coupled to an inverter latch 132. Each CAM cell 122 is also coupled to a pair of compare lines K0 and K1. Although, for clarity, only one CAM cell 122 is shown coupled to compare lines in FIG. 1B, it should be noted that all the CAM cells 122 are actually coupled to compare lines.
During a search operation, the precharge circuitry 128 precharges the match line 124 to a predictable state, which is generally low, to prepare for the search. The compare data, known as the comparand, is then compared to the bit pattern entry 120. Specifically, compare lines, such as compare lines K0 and K1, are used to compare the comparand to the data stored in the CAM cells 122. The current generator 126 begins to supply current to the match line 124. As the compare data is compared to the data stored in each CAM cell 122, the CAM cell will ground the match line 124 if the data stored in the CAM cell 122 does not match the compare data. Thus, if any CAM cell 122 does not match the compare data, the match line 124 will be pulled low. Conversely, if all the CAM cells 122 in the bit pattern entry 120 match the comparand, the match line 124 will remain high. The signal from the match line 124 is then sent through an inverter 130, and then to the inverter latch 132, which provides a high or low output, as described in greater detail below.
FIG. 1C is a diagram showing exemplary search signals 150 for a conventional CAM. The search signals 150 include an external clock 152, a first compare line K0154, a second compare line K1156, an internal clock 158, a match line 160, and a search output 162. As previously mentioned, during a search the compare lines 154 and 156 are used to provide search data to a particular CAM cell. Each compare line 154 and 156 will be set to either high or low, depending on the search data. Typically the compare lines K0154 and K1156 are set to the inverse of each other, however, when using a ternary CAM cell both compare lines 154 and 156 may be set to the same value. In the example of FIG. 1C, a first set of search data is placed on the compare lines for the first and second external clock cycle 150a and 150b. Then the search data is inverted in the third and fourth external clock cycle 150c and 150d. In addition, the data stored in the CAM cell matches the first set of search data, during the first and second external clock cycle 150a and 150b, and does not match during the third and fourth external clock cycle 150c and 150d.
To set the compare lines 154 and 156 to their appropriate values in a conventional CAM, each compare line 154/156 is first set to a predictable state of zero, or low. Then, one of the compare lines is asserted high. As shown in FIG. 1C, at the rising edge of the first external clock cycle 150a, both compare lines 154 and 156 are set low. Shortly thereafter, one of the compare lines is asserted high, in this case compare line K0154, thus in the first external clock cycle 150a, K0154 is asserted high and K1 remains low.
Next, at the rising edge of the second external clock cycle 150b, compare line K0154 is again set to a predictable state of zero. In this case, the search data for this particular CAM cell remains the same in the second external clock cycle 150b, thus compare line K0154 is again asserted high shortly after the rising edge of the second external clock cycle 150b. In a similar manner, both compare lines K0154 and K1156 are set to a state of zero at the beginning of the third external clock cycle 150c. This time the comparand changes, thus switching compare lines K0154 and K1156 such that K1156 is asserted high shortly after the rising edge of the third external clock cycle 150c, while K0154 remains low. At the rising edge of the fourth clock cycle 150d, both compare lines 154 and 156 are set to zero. The search data remains the same for the fourth external clock cycle 150d, thus compare line K1156 is again asserted high shortly after the rising edge of the fourth clock cycle 150d.
Thus, in a conventional CAM the compare lines are pulsed to compare the search data to the data stored in the CAM cell. This results in two transitions for every clock cycle of the external clock 152, regardless of the actual data being placed on the compare lines. As will be explained in greater detail subsequently, each transition requires increased power in the CAM to overcome the capacitance of the compare line.
Continuing with the above example, an internal clock 158 is used to control the search results in the conventional CAM. The internal clock 158 is an inverted clock, which is pulsed slightly after the compare lines 154 and 156 are set to the appropriate search value. As mentioned above, in the example of FIG. 1C the search data matches the data stored in the CAM cell during the first and second external clock cycle 150a and 150b, and does not match during the third and fourth external clock cycle 150c and 150d. Hence, at leading edge of the first internal clock cycle 158a, the match line 160 begins to ramp up, since the data stored in the CAM cell matches the comparand in the first external clock cycle 150a.
The rising match line 160 causes the inverted latch to output a high search output signal 162 during the first internal clock cycle. The precharge circuitry coupled to the match line 160 then causes the match line 160 to discharge and go low at the trailing edge of the first internal clock pulse 158a. As a result, during the leading edge of the second internal clock pulse 158b the output signal 162 is low. The output signal 162 then transitions to high after the match line 160 ramps to a sufficient level, later during the second internal clock pulse 158b. During the third and fourth external clock pulses 150c and 150d, the data stored in the CAM cell does not match the comparand. Hence, both the match line 160 and the output signal 162 are low during the third and fourth internal clock pulses 158c and 158d. Thus, during consecutive match results, the output signal 162 of the conventional CAM generally must transition from low to high during each internal clock cycle.
Each output 162 for each bit pattern entry of the CAM is coupled to a global match line, which is a long line that provides the search results to other areas of the CAM for further processing, such as to priority encoders. The long length of the global match lines results in each global match line having a large capacitance. As a result, every transition on a global match line requires a large amount of power to overcome the large capacitance. Since the output signals from the bit pattern entries propagate to the global match lines, every transition in the output signal results in a large power drain on the CAM. A similar result occurs with respect to the compare lines, each transition in the compare lines requires increased power from the CAM to overcome the capacitance of the compare line.
In view of the foregoing, there is a need for low power search methods for use in content addressable memory circuits. The methods should reduce the power required to perform searches in the CAM, and decrease the amount of transitions required during search operations.
Broadly speaking, the present invention fills these needs by providing systems and methods for reducing power in a CAM using sample words. In one embodiment, a method for low power searching in a CAM by testing a sample section of the bit pattern is disclosed. The method includes comparing a sample section of stored data to a corresponding sample section of search data. If the sample section of the stored data is different from the corresponding section of the search data, a non-match result is generated. However, if the sample section of the stored data is equivalent to the corresponding sample section of the search data, the remaining section of the stored data is compared to a corresponding remaining section of the search data. Thus, the remaining section of the stored data is not compared to the corresponding remaining section of the search data if the sample section of the stored data is different from the corresponding section of the search data. Generally, to reduce power in the sample test, the sample section is smaller than the remaining section of the bit pattern.
A match line for a CAM is disclosed in another embodiment of the present invention. The match line includes a sample match line coupled to a first set of CAM cells, and a sub-match line coupled to a second set of CAM cells. Sample circuitry is also included that is coupled to both the sample match line and the sub-match line. The sample circuitry provides current to the sub-match line if a sample section of search data corresponding to the first set of CAM cells is equivalent to the data stored in the first set of CAM cells. The sample circuitry preferably does not provide current to the sub-match line when the sample section of the search data corresponding to the first set of CAM cells is different from the data stored in the first set of CAM cells.
A content addressable memory is disclosed in a further embodiment of the present invention. The content addressable memory includes sample circuitry coupled to a first clock and a second clock. In addition, a sample match line is included that is coupled to the sample circuitry and to a first set of CAM cells. A sub-match line is also coupled to the sample circuitry and to a second set of CAM cells. The sample circuitry provides current to the sub-match line if a sample section of search data corresponding to the first set of CAM cells is equivalent to data stored in the first set of CAM cells. Conversely, when the sample section of the search data corresponding to the first set of CAM cells is different from the data stored in the first set of CAM cells, the sample circuitry does not provide current to the sub-match line. The first set of CAM cells coupled to the sample match line is compared to the corresponding sample section of search data during a clock pulse of the first clock, and the second set of CAM cells coupled to the sub-match line is compared to a corresponding remaining section of the search data during a clock pulse of the second clock.

System and method for low power searching in content addressable memories using sample search words


A ball-balancing drive assembly includes a ball having a ball surface and a reference axis extending through a centroid of the ball. Three omniwheel assemblies, each having a motor with a motor axle and an omniwheel configured to rotate around the motor axle are mounted on a chassis configured for supporting the three omniwheel assemblies at radially symmetric spacings with the motor axles oriented at an angle relative to the reference axis and the omniwheels oriented in mutually-orthogonal planes. Each omniwheel frictionally contacts the ball surface to convert rotational motion of the motor axle to torque on the ball.

Mobile robots can be broadly categorized as statically stable, e.g., stable when unpowered, and dynamically stable, e.g., stable only when powered. Statically stable robots generally have at least three wheels. A significant but frequently overlooked problem is that statically stable wheeled mobile robots can easily become unstable. If the center of gravity is too high, or the robot accelerates/decelerates too rapidly, or is on a sloping surface, or is pushed too hard, the robot can tip over. Thus, statically stable wheeled robots tend to have low centers of gravity and large bases. However, short, wheeled robots having large bases do not interact well with humans and have trouble maneuvering in environments that are crowded or cluttered.
A ball-balancing robot, or BBR, also known as a "ballbot", is a dynamically-stable mobile robot designed to balance on a single spherical wheel (i.e., a ball). Through its single contact point with the ground, a ballbot is omnidirectional and thus exceptionally agile, maneuverable and organic in motion compared to other ground vehicles. Its dynamic stability enables improved navigability in narrow, crowded and dynamic environments. The BBR works on the same principle as that of an inverted pendulum. It forms an underactuated system, in which there are more degrees of freedom (DOF) than there are independent control inputs. The ball is directly controlled using actuators, whereas the body has no direct control. The body is kept upright about its unstable equilibrium point by controlling the ball, much like the control of an inverted pendulum. This leads to limited but perpetual position displacements of the BBR. The counter-intuitive aspect of the BBR motion is that in order to move forward, the body has to lean forward and in order to lean forward, the ball must roll backwards. All these characteristics make planning to achieve desired motions for the ballbot a challenging task. In order to achieve a forward straight line motion, the ballbot has to lean forward to accelerate and lean backward to decelerate. Further, the ballbot must lean into curves in order to compensate for centripetal forces, which results in elegant and graceful motions.
BBRs exhibit rich 3D dynamics and are capable of fluid and graceful motion. Early research on BBRs appeared around 2006. The first successful ballbot was developed by Hollis and co-workers at Carnegie Mellon University (CMU), and is described in U.S. Pat. No. 7,847,504, which is incorporated herein by reference. This robot is also described by T. B. Lauwers, et al. in "A Dynamically Stable Single-Wheeled Mobile Robot with Inverse Mouse-Ball Drive", Proc. of the 2006 IEEE Int'l Conf. on Robotics and Automation, Orlando, Fla., May 2006, pp. 2884-2889. The described robot applies two roller bars to drive the ball in any direction but does not accommodate the ability to spin in place as the rollers used in the prior art act in interference of one another.
The omniwheel drive mechanism described by Wu et al. in U.S. Pat. No. 8,485,938, the disclosure of which is incorporated herein by reference, utilizes sets of guide rollers on axles that are arranged perpendicular to each other, i.e., 90° apart, so that the guide rollers contact the surface of the spherical wheel oriented to effectively define a cross pattern on the wheel that intersects a line corresponding to the wheel's north pole. The vertical positioning of the guide rollers limits the ability to spin in place.
Other ballbots have been described in the literature, including one developed by M. Kumagai and T. Ochiai, "Development of a Robot Balancing on a Ball", Int'l Conf. on Control, Automation and Systems 2008, Oct. 14-17, 2008, Seoul, Korea, pp. 433-438. This robot uses a single angle in engaging the ball while maintaining the drive motors vertically. This arrangement limits the mobility of the robot, and makes it difficult to spin in place. (The disclosures of both identified publications are incorporated herein by reference.)
To date, most BBR research has focused on human-scale designs, ball-balancing transportation vehicles, and knee-high to waist-high designs. A smaller scale robot, such as would be useful for entertainment, i.e., toys, service, education and research, is referred to as a "micro ball-balancing robot", or "MBBR", pronounced "Ember."
There are significant challenges and limitations to contend with when attempting to miniaturize a BBR. Tolerances become more stringent and cross-sectional areas decrease, lowering the yield strength of mechanical components. Scaling down the characteristic length scale (l) of a given design generally reduces the volume and mass of the design by l3; on a BBR, this significantly reduces the normal force between the omniwheels and the ball, creating problems with slip. Simultaneously, the time scale of the non-minimum-phase inverted-pendulum dynamics of a BBR is √{square root over (l/g)}, so as l is reduced, the time scale decreases, and the actuators must respond more quickly, further exacerbating the slip problem. In extreme cases, the drive wheels may even lose contact with the ball completely for short periods of time.
Earlier work on BBRs fall into two main categories: those driven by an inverse mouseball mechanism, and those driven by three omniwheels. In principle, neither category presents obvious barriers to miniaturization. The inverse mouseball mechanism relies on two perpendicular rollers that roll along the equator of the ball. A small, low-friction bearing is used at the top of the ball to support the weight of the upper body. Spring-loaded idler wheels at opposite points along the equator press the rollers against the ball to create enough friction to eliminate slip between the rollers and the ball. This allows the rollers to actuate the ball in the two horizontal directions independently.
There are two key problems with MBBRs driven by an inverse mouseball mechanism. The first was contamination. During testing, dirt and rubber particles can build up on the support bearing, idler wheels, and drive rollers. This increases friction and degrades performance to the point of failure. For large BBRs, the torques and forces involved are greater in magnitude, and tolerances are relaxed, so a thin layer of dirt has little effect on performance. However, for an MBBR, dirt buildup on the rotating components can be a critical point of failure.
A second problem encountered was the ball being pushed out of the socket during maneuvers. The rollers transmit torque to the ball by applying a friction force along the ball's equator. Depending on the direction of rotation, this force tends either to push the ball further into the socket, or to pull the ball away from the socket. The only force preventing the ball from leaving the socket is the weight of the robot itself. Since MBBRs have reduced mass, their weight is generally insufficient to keep the ball in the socket. Even if the ball does not leave the socket, the design suffers from asymmetric friction. As the roller actuates the ball in one direction, the ball is forced into the socket, increasing both the normal force and the friction at the top support bearing. When actuating the ball in the opposite direction, the friction at the top support bearing is reduced. Additionally, the inverse mouseball mechanism does not control the yaw of the robot about its vertical axis, so additional actuators would be needed to make the robot face in a desired direction. Given its significant problems, an inverse mouseball mechanism cannot be considered a viable choice for an MBBR.

Ball-balancing robot and drive assembly therefor

The Regents of the University of California


Syntheses of unsaturated piperidines from piperidones through a silyl piperidine reagent via the Shapiro reaction and palladium-catalyzed cross-coupling reactions with organo halides.

The present invention provides novel methodologies for the preparation of unsaturated piperidines, such as 3,4-unsaturated 4-arylpiperidines, from piperidones through silyl reagents via the Shapiro reaction and palladium-catalyzed cross-coupling reactions with organo halides, such as aryl iodides and bromides. Embodiments of this invention provide synthetic methodologies for making benzyl-protected, 3,4-unsaturated piperidine, which contains an aryldialkylalkenylsilane moiety, such as a benzyldimethylalkenylsilane moiety, from 1-benzyl-4-piperidone via the Shapiro reaction. This silyl piperidine readily undergoes palladium-catalyzed cross-coupling reactions with a variety of organo halides, such as aryl iodides and bromides, to generate 3,4-unsaturated piperidines, such as 3,4-unsaturated 4-arylpiperidines. Many of these coupling reactions according to this invention proceed at ambient temperature. These reactions present useful methods for 3,4-unsaturated piperidine and 4-arylpiperidine syntheses.
The 4-arylpiperidine moiety is commonly employed as a structural unit in numerous drug discovery programs, including those with potential application to the treatment of asthma,1 hypertension,2 depression,3 migraine headaches,4 bacterial infections,5 prostrate gland enlargement,6 estrogen-related disorders,7 neurodegenerative disorders (e.g. Alzheimer's disease),8 neuronal excitotoxicity (e.g. epilepsy, Parkinson's disease),9 cocaine abuse,10 and allergic rhinitis.11 Both the 4-aryl group and the N-substituent are frequently used as points of structural diversification within such programs.1,3c,4a,5,9,11
Because relatively few 4-arylpiperidines are commercially available, new synthetic routes to obtain such compounds are desirable. The most common methods that are currently applied include the condensation of a 4-piperidone derivative with an anionic aryl species (Scheme 1, Eq. (1)),3-4,8-12 the cross-coupling of a fully saturated piperidine reagent (Eq. (2)),13 and the cross-coupling of a 3,4-unsaturated piperidine reagent (Eq. (3)).1-2,5-7,14 The first of these three methods is often undesirable due to its harsh reaction conditions (i.e., strong nucleophiles and acids). The latter two methods are thus advantageous because they generally involve milder reaction conditions.

One disadvantage, however, that exists for the cross-coupling methods represented in Equations (2) and (3) is that the requisite piperidine reagents are generally not carried through multiple synthetic steps. They instead undergo the cross-coupling reaction immediately following their synthesis. Thus the manner in which a 4-arylpiperidine unit can be diversified within a drug discovery program is limited. This situation exists primarily because tin reagents introduce issues of toxicity and difficult by-product removal, while triflate, zinc, and boron reagents introduce issues of reagent instability and incompatibility.
Organosilanes have recently emerged as alternative cross-coupling reagents that possess the advantages of low toxicity and high stability.15 Benzyldimethylsilyl reagents in particular exhibit notable stability toward acids and bases,16 and they can be carried through multiple synthetic steps.17 It was ascertained in the context of this invention whether a 3,4-unsaturated piperidine reagent containing a benzyldimethylsilyl moiety could be readily synthesized and successfully employed in the cross-coupling reaction represented in Equation (3). Some embodiments of this invention provide the application of the Shapiro reaction to efficiently convert 1-benzyl-4-piperidone into a benzyldimethylsilyl reagent. Other embodiments of this invention provide the use of palladium-catalyzed cross-coupling chemistry to subsequently transform this reagent into a variety of 3,4-unsaturated 4-arylpiperidines. Still other embodiments of this invention provide the application of the Shapiro reaction to efficiently convert 1-benzyl-4-piperidone into a benzyldimethylsilyl reagent and the use of palladium-catalyzed cross-coupling chemistry to subsequently transform this reagent into a variety of 3,4-unsaturated 4-arylpiperidines.

Synthesis of unsaturated piperidines from piperidones with a silyl reagent


An apparatus for repairing a defective semiconductor device having an electrically short-circuited portion, wherein the semiconductor device includes a semiconductor thin film and a conductive thin film disposed in the named order on a conductive surface of a substrate and in which the conductive thin film and the conductive surface of the substrate are electrically short-circuited at a pinhole occurring in the semiconductor thin film to form an electrically short-circuited portion so that the semiconductor device is defective. The apparatus includes a substrate holding unit for holding the substrate of the defective semiconductor device and an electrode arranged above the substrate holding unit so that, when the defective semiconductor is positioned on the substrate holding unit, there is a predetermined distance between the electrode and the conductive thin film of the defective semiconductor device, the electrode being capable of moving in relation to the substrate of the defective semiconductor device. The apparatus further includes a voltage applying unit for applying a desired voltage to the electrode, wherein discharge is caused between the electrode and the conductive thin film of the defective semiconductor device by applying a desired voltage to the electrode through the voltage applying means to thereby modify a region of the conductive thin film of the defective semiconductor device in electrical contact with the conductive surface of the substrate of the defective semiconductor device.

1. Field of the Invention
The present invention relates to a method for repairing an electrically short-circuited semiconductor device by insulating portions of the device which are short-circuited due to pin holes and the like, an apparatus suitable for practicing said method, and a process for producing a semiconductor device by utilizing said method.
2. Related Background Art
In recent years, various studies have been made on large area semiconductor devices such as solar cell, flat panel display, photosensor, electrophotographic photosensitive device, etc. In addition public attention has been focused on non-single crystal semiconductors such as amorphous silicon semiconductors to constitute those large area semiconductor devices mainly because of their reasonable production cost.
For instance, there is known a pin junction type amorphous silicon solar cell as an example of such non-single crystal semiconductor device. In this solar cell, photocarriers occur in its semiconductor layer, comprising an amorphous silicon semiconductor thin film when light is impinged in the solar cell. The photocarriers migrate to its transparent electrode comprising a transparent conductive thin film situated on the side through which light is impinged and also to its conductive substrate situated opposite the transparent electrode by the action of an internal electric field, to thereby provide a photoelectromotive force.
The conductive thin film serving as the transparent electrode and the semiconductor thin film serving as the photosensitive semiconductor layer may be properly formed in a vacuum chamber in accordance with a plasma CVD method, a photo CVD method, a thermal CVD method, a vacuum evaporation method, or a sputtering method.
In the preparation of such amorphous silicon solar cell, due regard should be made to the problem relating to a short circuit which is often caused between the transparent electrode and the conductive substrate due to pinholes occurring at part of the semiconductor layer.
There are various causes for such pinholes to occur. For instance, in one case, since the transparent electrode is usually of some hundreds of angstrom in thickness and the semiconductor layer is usually of about 0.005 to some tens of um, minute dust particles (some micronmeter to some tens micronmeter in size) are deposited on the surface of the conductive substrate or they are deposited on or contaminated into the semiconductor layer during film formation to cause a removal for the conductive substrate or/and the semiconductor layer, whereby such pinholes occur at the semiconductor layer.
In other case, such pinholes occur when part of the semiconductor layer is removed due to its internal stress or its insufficient adhesion with the transparent electrode to furnish the conductive substrate with a region not having a desired semiconductor layer. In this case, the transparent electrode situated on the side through which light is impinged and the conductive substrate situated opposite said electrode are connected with each other through said region to be in an electrically short-circuited state. This results in significantly degrading of the characteristics required for a semiconductor device.
The occurrence of pinholes causing a short circuit is a serious problem particularly in the case of a large area semiconductor device such as solar cell, flat panel display, photosensor, electrophotographic photosensitive device, etc. In any case, it is extremely difficult to obtain a large area semiconductor device completely free of a short-circuited state region even under a clean environment substantially free of minute dust.
In order to solve the above problem relating to occurrence of pinholes causing a short circuit, Japanese Patent Publication 62(1987)-53958 (hereinafter referred to as Literature 1) proposes a method of making the inside of each of the pinholes occurring at the thin film semiconductor layer of a photosemiconductor to be in an electrically insulating state by perforating pinholes at its electrode layer and communicating the pinholes of the thin film semiconductor layer with the pinholes of the electrode layer. Likewise, Japanese Patent Publication No. 62(1987)-59901 (hereinafter referred to as Literature 2) proposes a method of reclaiming pinholes occurring at the thin film semiconductor layer of a semiconductor device by fusing the peripheries of the pinholes with radiation of energy beam.
FIGS. 10(A) and 10(B) are schematic views respectively for explaining the method according to Literature 1.
In FIGS. 10(A) and 10(B), numeral reference 1 stands for a translucent substrate, numeral reference 2 stands for a translucent electrode layer, numeral reference 3 stands for a semiconductor layer comprising a thin semiconductor film, numeral reference 4 stands for a back electrode layer, numeral reference 5 stands for a pinhole in a short-circuited state, numeral reference 6 stands for a pinhole provided at the back electrode layer, numeral reference 7 stands for laser beam, and numeral reference 8 stands for laser beam.
The method according to Literature 1 is to be explained with reference to FIGS. 10(A) and 10(B). That is, after a plurality of semiconductor devices have been prepared, semiconductor devices defective due to a short circuit are sorted out. As for each of those defective semiconductor devices, beam plane-scanning is performed while irradiating laser beam 7 through the other principal face of the translucent substrate 1 as shown in FIG. 10(A). When a short circuit current for the semiconductor device is measured at the time of performing the beam plane-scanning, a short circuit current does not flow when the laser beam 7 is irradiated to the portion where a pinhole 5 in a short-circuited state is present, and on the other hand, upon irradiating the laser beam 7 to the other portion where such short-circuited state is not present, a hole-electron pair is caused and migrates in the semiconductor layer 3, whereby a short circuit current flows. In view of this, the position where a pinhole 5 is present can be found for the semiconductor device by performing plane-scanning using the laser beam 7.
As for the portion of the semiconductor layer where a pinehole 5 is present, laser beam outputted from YAG pulse laser of 5.times.10.sup.6 W/cm.sup.2 in peak outputting power is radiated through the back electrode layer 4 in the way as shown by an arrow 8 to thereby remove a short-circuited state region comprising the constituent of the back electrode layer 4 which is extended to the inside of the pinhole 5. Particularly, as shown in FIG. 10(B), a pinhole 6 is made at the back electrode layer 4 formed on the semiconductor layer 3 having the pinhole 5 occurring therethrough at the time of the formation thereof such that it is coaxially in communication with the pinhole 5, whereby the inside of the pinhole 5 and that of the pinhole 6 are made to be in an electrically insulating state.
FIGS. 10(C), 10(D) and 10(E) are schematic views for explaining the method according to Literature 2.
In FIGS. 10(C), 10(D) and 10(E), numeral reference 1 stands for a translucent substrate, numeral reference 2 stands for a translucent electrode layer, numeral reference 3 stands for a semiconductor layer comprising a thin semiconductor film, numeral reference 4 stands for a back electrode layer, numeral reference 5 stands for a pinhole in a short-circuited state, numeral reference 7 stands for laser beam, and numeral reference 9 stands for a photosensor.
The method according to Literature 2 is to be explained with reference to FIGS. 10(C) through 10(E).
That is, a translucent electrode 2 is formed on a translucent substrate 1 and then, a thin film semiconductor layer 3 is formed on the translucent electrode 2. As for the device thus obtained, it is examined whether or not the semiconductor layer 3 is accompanied with a pinhole 5, by plane-scanning is performed for the semiconductor layer 3 while irradiating laser beam 7 outputted from an Ar gas laser of an extremely low Outputting power through the rear side of the semiconductor layer 3 and moving a photosensor 9 arranged on the side of the translucent substrate 1 and opposite the Ar gas laser in synchronism with the scanning of the laser beam 7 in the way as shown in FIG. 10(C), to thereby examine whether or not the semiconductor layer 3 is accompanied with a pinhole 5. In this case, if such pinhole 5 is not present at the portion of the semiconductor layer 3 where the laser beam 7 is irradiated, the laser beam 7 is absorbed by the semiconductor 3 and does not reach the photosensor 9. On the other hand, if such pinhole 5 is present at the portion of the semiconductor layer 3 where the laser beam 7 is irradiated, the laser beam 7 reaches the photosensor 9, and from a signal outputted from the photosensor 9 at that time, the position where the pinhole 5 is present is detected.
When the presence of the pinhole 5 is optically detected as above described, laser beam of about 2 to 3 W/cm.sup.2 in power outputted from, for example, an Ar gas laser of 514.5 nm in oscillating wavelength instead of the laser beam 7 is irradiated to the portion where the pinhole 5 is present to thereby fuse the peripheries of the pinhole 5 with respect to the semiconductor layer 3, whereby the pinhole 5 is filled up with the constituent of the semiconductor layer 3 in such a state as shown in FIG. 10(D). The filled portion of the semiconductor layer 3 exhibits a fused state at the beginning but it is sooner or later cooled, wherein the constituent of the filled portion is changed from amorphous state to polycrystalline state or the like and the junction state is eventually broken. Thus, the filled portion finally becomes to function substantially as an insulator.
Finally, as shown in FIG. 10(E), a 2000 to 10000 thick aluminum layer serving as a back electrode 4 is laminated on the semiconductor layer 3 having the above filled portion by a vacuum evaporation technique.
The above mentioned two methods are effective in order to solve the foregoing problems relating to short circuit caused due to pinholes occurring at the semiconductor layer to a certain extent, but there still exist such problems as will be mentioned below, which are necessary to be solved.
In the case of the method according to Literature 1, there is a problem that it takes a long period of time in order to detect a number of pinholes being present at the semiconductor layer of a large area by way of the laser beam scanning process.
There is also other problem for the method according to Literature 1 that, in this method, as apparent from FIG. 10(B), the pinhole 6 is left as it is in any case, however, such pinhole must be filled up in practice. That is, in the case of a semiconductor device having such a configuration as shown in FIG. 10(B) in which the pinhole 6 is left without being filled up, water, alkaline metal, or the like are apt to enter therethrough upon use, and once water or/and alkaline metal, etc. have entered thereinto, the semiconductor device will be deteriorated shortly. However, in order to fill up such pinhole as shown in FIG. 10(B), not only a specific technique is required but also it takes time, and because of this, the resulting product becomes unavoidably costly.
Likewise, there are some problems also for the method according to Literature 2. That is, in the case of the method according to Literature 2, as apparent from what shown in FIG. 10(D), the pinhole 6 is filled up by fusing the peripheries thereof, but this process is performed prior to forming the back electrode layer 4, and because of this, a pinhole which will be caused at the time of forming the back electrode layer on the semiconductor layer 3 having the filled portion is unavoidably left without being filled up. In addition to this, since the fill up of the pinhole 5 is performed through the laser beam-irradiating process which takes time while exposing the semiconductor layer 3 to environmental atmosphere, the quality of the semiconductor 3 is apt to deteriorate during the filling up process.
There is a still further problem for the method according to Literature 2 in that it takes a long period of time in order to detect a number of pinholes being present at the semiconductor layer of a large area by way of the laser beam scanning process and it is extremely difficult to fill up all such numerous pinholes uniformly by way of the laser beam fusing process.
In view of the above, in the case of the method according to Literature 2, if a desirable semiconductor device should be obtained, it will be costly.

Apparatus for repairing an electrically short-circuited semiconductor device


A protective hood assembly (6) for a tool machine (2) is formed of a housing with a protective hood (10), to a securing assembly (8, 8′, 8″) relative to the housing (4) in different rotary positions, wherein at least one lock-in part (30, 30′) is provided, which can be brought along a direction of installation (M) into a receiving region (36) of a locking housing (16) of the securing assembly (8) and at which, by rotating, can be brought into a bayonet-like engagement and wherein locking means (32, 32′) are provided on the protective hood, the locking means being capable of being locked in different locking positions with counter locking means (26, 26′) of the securing assembly (8). The receiving region (36) is limited on a side facing the housing (4) at least in part by an abutting wall (34, 34′, 34ä, 34″b), which is mobile.

This type of protective hoods have the advantage that the protective hood is installed and removed on the tool machine without the use of tools. In addition, the protective hood in the secured condition, depending on need, can be brought, relative to the tool machine, also without the use of tools from one locked position into another.
CH 682 732 A5 discloses a protective hood arrangement, where the protective hood has an annular holding part, on which two brackets project inwardly. At one fastening flange of the tool machine, an annular receiving groove formed by two access recesses towards the free end of the fastening flange extend, whose cross-section and arrangement correspond to the form and arrangement of the brackets on the protective hood. When installing the protective hood, the brackets are urged over the access recesses into the receiving groove and then by rotating, together with the later brought into a bayonet-type engagement. In addition, on an underside of the tool machine, around the fastening flange, depressions are formed into which locking cams of the protective hood can interlock and which project axially on a free end part of an annular holding part.
The drawback in the prior art protective hood arrangement is that the features for the optional fixing of the protective hood in different locking positions are relatively expensive and consequently result in high costs of manufacture. In addition, the receiving groove in cross-section must be relatively precisely matched to the thickness of the brackets, in order to prevent a disturbing rattling during operation. At the same time, this precise matching of the receiving groove to the dimensions of the brackets results in a slight sticking, particularly when the brackets are slightly bent. This can result in a misalignment of the protective hood into a new locking position or can result in substantial problems at the time of their installation or dismantling.


A shot blasting machine for shot blasting wire or rod-like material is of the kind comprising two centrifuge wheels in a closed housing which has an inlet for blasting shot or sand, means for conducting the wire rod material to be blasted through the housing between the centrifuge wheels, and an outlet for scale blasted from the wire or rod material. The centrifuge wheels are rotated in the same direction as each other, the region between the wheels where blasting takes place is divided into two sections by a wall, which permits the passage of the material to be blasted through the region, the shot or sand, in operation passing from one wheel to the other wheel in one section and from the other wheel to the one wheel in the other section, and a guide device being disposed adjacent each centrifuge wheel one in each section to direct the shot or sand from the wheel against the material to be blasted. This arrangement economizes in power because the shot circulates through the two wheels and impinging streams of shot are avoided so that there is no destruction of the energy of the shot, and also the wear of the shot is minimized.

This invention relates to shot or sand blasting machines for use in shot or sand blasting material in the form of wire or rod, the machine being of the kind comprising two centrifuge wheels in a closed housing which has an inlet for blasting shot or sand, means for conducting the wire or rod material to be blasted through the housing between the centrifuge wheels, and an outlet for scale blasted from the wire or rod material.
In one such machine the two centrifuge wheels are driven in opposite directions from each other, so that the blasting shot or sand from one centrifuge wheel impinges upon the blasting shot or sand from the other centrifuge wheel approximately in the region in which the wire or rod material is blasted. As a result the energy transmitted by the centrifuge wheels to the blasting shot is continually destroyed. This means that this energy must be repeatably renewed. Furthermore, the blasting shot or sand itself is subject to comparatively high wear. The blasting shot flung out from the centrifuge wheels collects at the bottom of the housing and is conveyed upwards again by an externally situated conveyor and is fed back again to the inlet regions of the centrifuge wheels. Along this transportation route of the shot or sand, scale or other material abraded from the rod or wire is separated from the shot or sand. This arrangement is disclosed in French Patent Specification No. 1,268,599.
A shot blasting machine is also known, in which three centrifuge wheels are arranged in a star pattern staggered from one another around the path of the material to be blasted in the direction of movement of this material. With each centrifuge wheel there is associated a guide device consisting of two adjustable guide plates. The guide devices feed the blasting material issuing from the centrifuge wheels against the material to be blasted. The shot or other blasting material here again collects in the lower region of the housing and must be supplied thence to the centrifuge wheels by separate conveyors. This machine is described in German Specification No. 1,815,187.
The main object of the present invention is to provide a shot blasting machine of the kind initially described which can be operated with a lower energy consumption, which is constructed as compactly as possible, and in which minimum wear of the blasting shot or other blasting material takes place.


This application provides an apparatus and method for detecting online failure and a system. The apparatus includes: a reading unit configured to read signal to noise ratios of subcarriers from a receiver of a multicarrier optical communication system according to a predetermined monitoring time interval; a judging unit configured to judge whether there exist a first predetermined number of subcarriers of which the signal to noise ratios are less than a first threshold value; a detecting unit configured to monitor a change of distortion of the system when it is judged yes by the judging unit, and determine a cause of degradation of signal to noise ratios according to the change of distortion of the system; and a reporting unit configured to report degradation of signal to noise ratios and/or the cause of degradation of signal to noise ratios. With the apparatus and method and system provided by this application, changes of distortion of the system may be monitored on line, and the changes possibly posing a threat to normal operation of the system may be early alerted, thereby making it possible to perform targeted adjustment in advance.

1. Field
The present disclosure relates to a multicarrier optical communication system, and in particular to an apparatus and method for detecting online failure and a system.
2. Description of the Related Art
A multicarrier communication system is a communication system based on multicarrier modulation, which is widely used in wireless communications and wired access networks due to its advantages of high transmission rate, high spectrum efficiency and anti-multipath and frequency domain fading. In a short-haul optical communication application, a multicarrier communication system, especially a discrete multi-tone (DMT) system based on intensity modulation and direct detection, gains much attention in the industry due to its simple structure and high transmission rate, and is deemed as one of leading technologies in a short-haul optical communication application scenario, such as a next-generation data center, etc. (refer to Document 1).
However, different from conventional wireless communication and a wired access network, on the one hand, a rate of a DMT optical communication system is greater than or equal to 100 Gb/s, and at such a high rate, influence of a change of a system distortion on the performance of the system will be enlarged; and on the other hand, a typical application scenario, such as a data center, has a higher requirement on stability of the DMT optical communication system, which often requires the system to be able to ensure operating consecutively at a stable rate. While in the known art, the DMT system tracks only changes of signal to noise ratios (SNRs) of the subcarriers, simply attributes a cause of the changes of the SNRs to changes of system noises and crosstalk, and attempts to ensure continuity of traffics in a subcarrier bit swap manner (refer to Document 2).
It can be seen that, the known art does not solve two key problems of the DMT optical communication system. First, localization of the cause of the changes of the SNRs. As the communication rate of the DMT optical communication system is very high, slight changes of various distortion in the system, such as a clock jitter, etc., will bring changes of the SNRs, while such degradation of the SNRs is not brought by noises or crosstalk, hence, the continuity of the traffics cannot be ensured by the subcarrier bit swap. Second, assurance of a stable transmission rate. As facing to terminal users, the conventional wireless communication and wired access network do not require the stability of the transmission rate, and hence, the known art deals with the changes of the SNRs based on adjusting the transmission rate. However, the DMT optical communication system is used in such scenarios as interconnection of large-scale servers in the data center, and requires that the transmission rate of the system is stable, such as satisfying specifications of a 100 Gb/s Ethernet, etc.
Document 1: "Discrete Multi-Tone for 100 Gb/s Optical Access Networks", Takahara, T.; Fujitsu Labs. Ltd., Optical Fiber Communications Conference and Exhibition (OFC), 2014; and Document 2: "Adaptive Channel Tracking and Bit-Power Reallocation for 100 Gb/s Uncooled DMT Transceiver", Bo Liu; Weizhen Yan; Lei Li; Hao Chen; Zhenning Tao; Takahara, T.; Rasmussen, J. C.; Drenski, T. Optical Communication (ECOC), 2014.
It should be noted that the above description of the background is merely provided for clear and complete explanation of the present disclosure and for easy understanding by those skilled in the art. And it should not be understood that the above technical solution is known to those skilled in the art as it is described in the background of the present disclosure.

Apparatus and method for detecting online failure and system


This invention discloses a monostable multivibrator which is useful for an FM detector circuit of a pulse count system. The monostable multivibrator has a time constant circuit which includes a capacitor, an amplifier circuit which receives an output of the time constant circuit, a positive feedback circuit which is connected between an output end of the amplifier circuit and an input end of the time constant circuit, and a trigger terminal which is disposed in a circuit loop constructed of the time constant circuit, the amplifier circuit and the positive feedback circuit; and is characterized in that the amplifier circuit is a differential amplifier which is made up of a pair of transistors connected in the differential form, the transistors being connected in common through emitter resistances connected in series with respective emitters thereof. Thus, the monostable multivibrator can provide pulse signals of a fixed pulse width without being influenced by noise.

This invention relates to monostable multivibrator circuits, and more particularly to a monostable multivibrator circuit for use in an FM detector circuit of a pulse count system.
A monostable multivibrator circuit usually has a time constant circuit which includes a capacitor, an amplifier circuit which receives an output from the time constant circuit and which has an input threshold voltage, a positive feedback circuit which is connected between an output end of the amplifier circuit and the time constant circuit, and a trigger terminal which is disposed in a circuit loop constructed of the time constant circuit, the amplifier circuit and the positive feedback circuit.
The output pulse width of this circuit is determined by a period of time during which the output signal level of the time constant circuit exceeds the input threshold voltage.
The inventors constructed a monostable multivibrator by employing differential amplifier transistors for the amplifier circuit and the positive feedback circuit. As a result, it has become possible to determine the input threshold voltage by a potential which is applied to the base of one of a pair of transistors of the differential amplifier. In this case, the input threshold voltage is decided by the external potential, not by the characteristic of an element itself as in the case of, for example, utilizing the base-emitter voltage of a transistor. Therefore, the input threshold voltage can be freely set and can be made a stable value without being influenced by a variation in the characteristic of the element itself.
Moreover, it has become possible to operate the differential amplifier transistor in the non-saturated state in such a way that the quantity of a voltage drop to appear in a collector load is limited by the current of a current source connected to the emitter of the transistor. Therefore, the lowering of a current gain and the accumulation of carriers in a collector region or a base region which are attributed to the saturated operation of the transistor do not occur, and an output signal of comparatively good waveform and quick response can be obtained.
Further, experiments and studies, however, have revealed that, in the monostable multivibrator employing the differential amplifier transistors as described above, the operation resetting time is susceptible to influences of noise, so that the output pulse width is not fixed.

Monostable multivibrator and FM detector circuit employing common emitter transistor amplifier with plural emitter resistors to avoid circuit operation from signal noise


The present invention is directed to the measurement of soluble leukocyte surface markers, soluble T cell growth factor receptors, soluble complement receptors, soluble T cell differentiation antigens, or related soluble molecules or fragments thereof, and the use of such measurements in the diagnosis and therapy of diseases and disorders. The invention is also directed to the measurement of soluble CD35 (sCD35) or fragments thereof, and the use of such measurements in detecting disease or disorders. A polyclonal sandwich assay is provided for the detection and/or measurement of soluble CD35. The invention further relates to the measurement of total leukocyte markers or fragments thereof, and the use of such measurements in the detection and diagnosis of diseases or disorders. The term "total" leukocyte marker used herein refers to the total amount of a leukocyte marker in a sample, including that present in membrane and intracellular compartments and extracellular soluble compartments. Measurements of a total leukocyte marker can be used to determine the approximate amount in a body fluid sample of leukocytes positive for the leukocyte marker. In a further embodiment, the invention relates to the measurement of both the amount of total leukocyte marker and the amount of the soluble form of the leukocyte marker and a comparison of the measured levels.

2.1. LEUKOCYTE SURFACE MOLECULES
Clusters of differentiation (CD) have been established which define human leukocyte differentiation of antigens (Bernard and Boumsell, 1984, Hum. Immunol. 11:1-10; Knapp et al., 1989, Immunol. Today 10:253:258; Gebel et al., 1988, ASHI Quarterly 12:11; Leukocyte Typing III: White Cell Differentiation Antigens. Ed., McMichael, A. J. 1987. Oxford University Press. Oxford), by the comparison of reactivities of monoclonal antibodies directed against the differentiation antigens. The T cell surface antigens, their classification into epitope-defined subgroups, and their distributions on T cells have been studied by use of monoclonal antibodies directed against human T cells (Clark et al., 1983, Immunogenetics 18:599-615; Hansen et al., 1984, in Leucocyte Typing, Bernard, A., et al., eds., Springer-Verlag, New York, pp. 195-212). Some of the T cell clusters of differentiation and other T cell surface molecules are listed in Table I.
These T cell surface markers serve as markers of the cell lineage, the identity of the functional T cell subset to which the T cell belongs, and the activation state of the T cell. Several of the cell surface molecules have been studied in great detail, have been found to be important in initiating and regulating immune functions and are critical to communication processes between immune cells.
TABLE I __________________________________________________________________________ LEUKOCYTE SURFACE MOLECULES Leukocyte Detection Surface Monoclonal Marker Expression Antibodies References __________________________________________________________________________ T cell Antigen Receptor All T cells and T cell subsets T40/25, .alpha.F1, .beta.F1, 1, 2, 3, 4, 5, 6 TCR.delta.1, C.gamma.M1 CD1 Thymocytes & Langerhans OKT6 Cells, Leukemia Cells NAI/34 NK cell receptor NK cells NC-37 specific 7 antibodies Cell Adhesion Molecules CD2 All T cells OKT11 8, 9, 10 Leu5 B67.1 CD58 (LFA-3) Leukocytes, epithelial TS2/9 11 CD3 Pan T cell OKT3 12 Leu4 CD4 Helper/Inducer Subsets OKT4 12 of T cells Leu3a CD5 T. B subsets UCHT2 11 T1 CD7 T Cells 3AI 11 CD8 Supressor/Cytotoxic .alpha. Chain: OKT8 13, 14 Subsets of T cells Leu2a .beta. Chain: T8/2T8 14a .beta.2 integrins LeuCAM leukocyte cell adhesion 11 molecules CD11a (LFA-1) myeloid, lymphoid 11.15 CD11b myeloid 11, 15, 16, 17, 18, 19 (MAC-1 (CR3)) CD11c (CR4) myeloid 11, 15 CD16 (FcR111) Natural Killer, Macrophages HUNK2 11 Granulocytes 3G8 CD21 (CR2) B subset B2 11, 20 HB5 CD23(FC.epsilon.R11) B subset MHM6 11 Blast-2 CD25 TAC, IL-2 Receptor Anti-TAC 21 (Activated T Cells) 7G7/B6 CD30 Activated T, B Cells Ki-1 11 Reed-Steinberg Cells HSR4 CD35(CR1) Granulocytes, B cells, YZ-1 11, 22 monocytes J3D3 .beta.3 integrins CD41 11, 23 CD51 11, 23 Homing Receptors CD44 Leukocytes, brain 33-3B3 24 Mel-14 GRHL1 25, 26 .beta.1 Integrins CD49a-f(VLA-1, Extracellular 27, 23 VLA-2, VLA-3, VLA-4, Matrix (ECM) VLA-5, VLA-6) CD56(NKH1, NCAM) Natural Killer NKH1 11 Activated lymphocytes Leu19 CD71 Transferrin Receptor, 11, 28 Proliferating cells __________________________________________________________________________

Therapeutic and diagnostic methods using leukocyte surface antigens


One or more techniques and/or systems are provided for dynamic data access configuration. For example, a mapping may be maintained for compute nodes of a distributed processing system. The mapping may comprise access permission assignments of at least some compute nodes to shared data segments (e.g., read access and/or write access permissions). The mapping may be updated based upon configuration changes for the distributed processing system (e.g., addition of a new compute node, failure of a compute node, granting or removal of access to a shared data segment for an existing compute node, etc.). The updated mapping may be applied to the distributed processing system during operation of the distributed processing system (e.g., access may be granted to original instances of shared data segments based upon the configuration change; compute nodes and/or the distributed processing system may be kept online and operational while applying the configuration change; etc.).

A distributed computing or processing system comprises multiple computers, such as compute nodes or processing nodes, which operate relatively independently to achieve a common goal. Data processing, analytics, and/or other jobs may be performed using distributing computing (e.g., hundreds or thousands of compute nodes may process a relatively large data set to accomplish a job). A scheduler may be used to schedule tasks, corresponding to portion of a job, which are to be performed by various compute nodes.


A decontamination operation chamber is partitioned into a first operation chamber and a second operation chamber. A connecting portion that connects the first operation chamber and the second operation chamber can be closed. The pressure of the first operation chamber and the second operation chamber is adjusted by a pressure-adjusting mechanism. When the connecting portion is opened and the first operation chamber and the second operation chamber are connected, an inlet portion for the first operation chamber and an outlet portion for the second operation chamber are closed and air flow is generated from the second operation chamber to the first operation chamber by the pressure-adjusting mechanism. When carrying an object into an aseptic manipulation chamber, the object is housed in the first operation chamber and a first decontamination operation is performed, then the object is transferred to the second operation chamber and a second decontamination operation is performed.

Conventionally, as disclosed in PATENT DOCUMENT 1, for example, an aseptic manipulation system is partitioned into an aseptic manipulation chamber, the inside of which is kept in an aseptic condition, and a pass box connected to the aseptic manipulation chamber. A communication portion formed between the aseptic manipulation chamber and the pass box, and an inlet portion provided in an outer wall of the pass box, can be hermetically closed by an open-close member, respectively. Microbes adhering to a surface of an object carried into the aseptic manipulation chamber are removed therefrom by decontamination gas (i.e., decontamination vapor) in the pass box. After that, the inside of the pass box is subjected to aeration, so that decontaminants remaining on the object and an inner wall of the pass box are removed, and the pass box and the aseptic manipulation chamber are then in communication with each other, and the object is transferred into the aseptic manipulation chamber.
According to the above-described conventional aseptic manipulation system, the inside of the pass box is filled with decontamination gas to remove microbes, so that not only the object but also the inner walls of the pass box, which has been opened to the external environment for introducing the object, are sterilized, and the pass box is then in communication with the aseptic manipulation chamber while keeping the sterilized condition. Therefore, the aseptic manipulation chamber and the pass box are maintained in a grade D cleanliness environment of air, which is a slightly higher cleanliness grade than the general environment.
PATENT DOCUMENT 1: Japanese Unexamined Patent Publication No. 2010-51351


The present invention relates to a process for the elimination of heavy metals from a closed white water system within the pulp and paper industry, wherein one adjusts the pH of the white water to between 5 and 11, and that one subsequently precipitates the resins present using a flocculation agent, whereby by a simultaneous elimination of the heavy metals is obtained.

Today, within the pulp and paper industry, there is a more frequent closing of the white water systems. This is, as such, a positive environmental factor, by reducing the discharge to different recipients, but means increased problems, as well, within the industry by accumulation of different compounds in the white water systems as closed. Thus there is an accumulation of resins and heavy metals in the white water, which different compounds have to be eliminated in order not to create problems at the production of paper and pulp at the renewed use of the white water. Resins and heavy metals are present in different concentrations in the wooden raw materials depending on its origin.
The resins can be precipitated chemically by using flocculation agents followed by flotation or sedimentation whereby the white water as such can be treated using such a flocculating agent.
One has, however, not known how to treat the heavy metals.

Process for the elimination of heavy metals


A DC voltage converter is provided that cyclically converts an input-side supply voltage into an output voltage. The converter includes an inductive storage element connected between a terminal for the supply voltage and, in a manner such that it is coupled via a first switch, a reference potential terminal. The capacitively buffered output voltage terminal is connected, via a second switch, between the inductive storage element and the first switch. Provision is furthermore made of a third switch, which is intended to selectively short the inductive storage element that is connected in parallel and is controlled by a control circuit. The control circuit is controlled, on the input side, by a control voltage that is tapped off at the second terminal of the inductive storage element.

DC voltage converters are used in portable devices in which the batteries provide only a low supply voltage on account of the desired miniaturization and weight saving. In order to supply the circuit units of the devices, a DC voltage converter converts the supply voltage into a higher output voltage. The design of such a DC voltage converter (which is also referred to as a step-up converter) is described in Tietze/Schenk: "Halbleiterschaltungstechnik" [Semiconductor circuit technology], 12th edition, pages 948 to 949.
A DC voltage converter has an inductive storage element, which is connected between a terminal for the supply voltage and, in such a manner that it is coupled via a first switch, a terminal for the reference potential. A capacitively buffered terminal for the output voltage is connected, via a second switch, between the inductive storage element and the first switch.
During ideal cyclic operation, the first switch and the second switch change over simultaneously, with the result that either the first switch is on and the second switch is off or the first switch is off and the second switch is on, respectively. If the first switch is on, energy is stored in the inductive storage element. The charge is removed if the second switch is on, and the capacitor is charged. If the switching states of the first and second switches remain unchanged, the coil current falls continuously until the inductive storage element has been discharged.
If the first and second switches are on, the energy stored in the capacitor drains via the second and first switches. This impairs the efficiency of the DC voltage converter.
If the first and second switches are off at the same time and energy is still stored in the inductive storage element, the coil current is interrupted and voltage spikes which may damage the circuit occur. In addition, interfering oscillations occur, said oscillations being caused by the resultant resonant circuit that is formed from the inductive storage element and the parasitic switch capacitance.
In practice, the first and second switches cannot be changed over at exactly the same time on account of propagation times and other effects. Therefore, it is difficult to avoid the first and second switches being off at the same time. The first and second switches may likewise be on at the same time. This state is usually avoided on account of the efficiency being greatly reduced. In addition, it is also sometimes desired, when regulating the circuit, that the first and second switches are off at the same time so that the output voltage assumes a prescribed value. In order to suppress the associated voltage spikes or voltage oscillations, the inductive storage element is shorted, with the result that the coil current flows in the short-circuit circuit. Such a circuit is also referred to as a snubber circuit. A snubber circuit has hitherto usually been formed by a series circuit comprising a diode and a series resistor, said series circuit being connected in parallel with the inductive storage element. The series resistor is used to set a voltage value, at which the inductive storage element is shorted. The voltage value may not be less than the threshold voltage of the diode, which, in integrated circuits, is possibly already a critical value.
The problem is that both the diode and the resistor must be dimensioned as accurately as possible (which is associated with outlay in terms of technology and costs) so that, on the one hand, the inductive storage element is shorted at a desired threshold value and, on the other hand, the losses on account of the voltage drop across the resistor are not too large.

Cyclical DC voltage converter for suppressing voltage spikes and oscillations


An apparatus for supporting an arts and crafts project during the creation, decoration, repair, or display of the project. The support apparatus includes a support rod upwardly projecting from a base positionable upon a support surface such as a table top. A hanging module, which may be variously shaped including peg or hook shapes, inserts into vertically spaced holes in the support rod, and the project is hangable from the hanging module. Adjustment of the height of the hanging module to customize the support apparatus to different sized projects can be performed by inserting the hanging module into a different hole in the rod. The present invention also provides a stabilizer for limiting twisting of the arts and crafts project hanging from the hanging module.

The present invention pertains to devices used in arts and crafts activities, and, in particular, to a device used to support an article such as a wreath being worked on by a craftsperson.
Countless people participate in a wide range of creative activities which are commonly referred to as arts and crafts activities. Representative activities range from basket and wreath making to woodworking projects. The reasons for which people partake in these activities are numerous and very diverse. For example, arts and crafts activities may be performed to serve as an outlet for creative impulses, or as a method of relieving stress, or possibly as a means of economic gain.
One popular arts and crafts activity involves making and/or decorating hanging adornments such as wreaths. Wreaths fabricated from materials such as twigs, styrofoam, wire, straw, paper mache, etc., can be purchased or made, and then decorated in an individualistic fashion which is aesthetically pleasing to the craftsperson. Wreath decorating typically involves affixing various items including flowers, greenery, figures, bows, ribbon, and cloth to the wreath with materials such as wire, string and/or glue or alternative adhesives.
While the process of transfiguring a wreath to enhance its appearance can be a fulfilling experience for the craftsperson, one aspect of the process can be especially problematic. In particular, for many people, the hassles of holding and maneuvering the wreath during the transfiguration process is frequently an annoying and inconvenient task which interferes with decorating.
Specifically, when decorating a wreath, a craftsperson typically rotates the wreath to center the wreath, i.e. identify the rotational orientation where the wreath looks best. A hangar for eventually mounting the wreath may be fashioned from a piece of wire or other element and attached to the wreath at this stage of decoration. Then, the craftsperson begins attaching the materials such as the bow or ribbons to the wreath. During this attaching or decorating process, due to the lack of a more viable alternative, many people resort to setting the wreath flat on a support or work surface such as a table top. Before adding each new decoration, a craftsperson frequently picks up the wreath from the support surface to recenter the wreath which may have shifted during decorating and to check how the decorations look in a frontal, mounted view. Besides being tedious, this continual recentering of the wreath provides abundant opportunity for displacing or disturbing those decorations previously placed.
Resorting to placing wreaths on a table top during decorating also may undesirably slow the decorating process. For example, when glue or another adhesive is employed to affix decorations, especially decorations which are attached on the back side of the wreath normally laid on the table top, drying time is required for the glue before the wreath can be returned to its normal arrangement on the support surface. When the wreath has to be set down on, for example, its front surface during glue drying, no further decorating of the front of the wreath can be undertaken. Consequently, a wreath or other hanging adornment that might otherwise be decorated within a several hour period takes up table or counter space for a longer time while waiting to be finished. As many craftspersons decorate or create as a hobby and therefore work in their homes, for example at their kitchen tables, the drying wreaths take up important space and may have to be moved out of harms way at some point during their drying, increasing the likelihood of disturbing the placed decorations.
To overcome these problems, during the decorating process some craftspersons hang the hanging adornment from a hook placed in pegboard that has been mounted on a wall. Unfortunately, this technique is not always practical to all craftspersons for a variety of reasons. For example, besides the obvious problem that not everyone has a pegboard equipped wall, even those with access to pegboard also need a table, counter-top or other surface adjacent to the pegboard on which the decorations can be placed in order to make decorating convenient. In addition, the lack of portability is a shortcoming, as this technique does not allow a craftsperson the freedom to work wherever she/he desires, such as out on a picnic table on a nice day.
Thus, it would be desirable to provide a device which overcomes these shortcomings of the prior art.

Support apparatus for arts and crafts project


An optical recording medium is disclosed, which has a substrate and a recording film formed on the substrate. The recording film has a film comprising tin as the main component and passive state-forming metal layers formed on both sides of the tin film. The optical recording medium has a high recording sensitivity, a good signal quality and a high reliability. The optical recording medium is prepared by forming a first passive state-forming metal layer, a film comprising tin as the main component and a second passive state-forming metal layer in sequence on a substrate, and preferably heating the thus-obtained laminate.

(1) Field of the Invention
The present invention relates to an optical recording medium comprising a recording film of a metal formed on a substrate. In this optical recording medium, the metal film is irradiated with laser beams to melt or evaporate the film and form small pits or cause deformation, whereby information can be recorded at a high density, and reproduction is performed by utilizing changes in the light reflectance or transmission in the recorded areas.
(2) Description of the Related Art
A process is known in which laser beams are converged on a recording film formed on a disk-shaped transparent substrate of a glass or plastic material and a physical deformation, a phase change or the like occurs in the laser beam-converged portion of the recording film, and information is recorded by utilizing this deformation or change. If a high output laser such as an argon laser is used as the laser beam source for recording, a film of a high-melting-point metal having a high oxidation resistance can be used as the recording film, and the range of selection of the recording film is expanded. But the size of the recording and reproducing apparatus, per se, is increased and an expensive modulator must be provided for modulation of the laser beams, and thus this process is not suitable for practical application. Accordingly, semiconductor lasers are mainly used at present, but semiconductor lasers have problems in that the wavelength of laser beam is limited to that in the near-infrared region and the output is low. Accordingly, a recording medium of a heat mode optical recording medium used for recording information according to the above-mentioned process must have a high absorption to light in the near-infrared region.
The heat mode optical recording medium most frequently used at present is the type wherein pits are formed in a laser beam-converged portion and information is recorded by utilizing these pits. In order for this optical recording medium to show good recording characteristics, the material of the recording film must have a low melting point, the material must have a low heat conductivity, the material must have an appropriate light reflectance, and pits having a good shape must be formed. As the conventional material of the optical recording film satisfying these requirements, there are known films prepared by vacuum deposition or sputtering of metals such as tellurium, bismuth, selenium and tin, alloys composed mainly of these metals and composites of these metals or alloys with organic materials or oxides, and films formed by spin-coating of organic dyes having a light absorption band in the near-infrared region.
Especially, a film of tin formed by vacuum deposition or sputtering has a low melting point and high light absorption and reflectance in the near-infrared region, and therefore, a recording film of the pit-forming type having a high recording sensitivity and a high contrast ratio can be obtained from tin. Moreover, this recording film is advantageous over other metal type optical recording materials in that the material is cheap and has a low toxicity.
Although the tin film has the above-mentioned characteristics, a film of tin formed by vacuum deposition or sputtering has a cohesion structure and the surface is roughened, and therefore, if recording and reproduction are carried out on this recording film, the noise due to the surface condition of the film is large and a good C/N ratio cannot be obtained. Moreover, the tin film is often deteriorated by oxidation, and if the tin film is allowed to stand in air for a long time, a reduction of the reflectance and a formation of pinholes occur.
As the means for obviating the foregoing defects without degradation of the high sensitivity possessed by the tin film, there can be mentioned a method in which another metal is added to tin, a method in which a compound of tin is used, and a method in which fine particles of tin are dispersed in a tin compound. Since films prepared according to these methods, which comprise tin as the main component, are composed of fine particles of tin, the above-mentioned noise due to the surface condition of the film is drastically reduced. Furthermore, according to these methods, the oxidation resistance of the film is increased, and reduction of the reflectance of the recording film or degradation of the recording-reproducing characteristics, caused when the film is stored at room temperature for a long time, can be controlled to a high degree.
As the substrate acting as a support for the recording film, a glass substrate, a plastic substrate composed of polymethyl methacrylate, polycarbonate, an epoxy resin or the like, and a substrate which is formed by coating a recording film-forming side of a substrate as mentioned above with an ultraviolet ray-curable resin or the like for formation of a guide groove or the like, are often used.
Especially, the plastic substrate is frequently used because the molding is easily performed, little cracking occurs handling is easy, and the heat conductivity is low.
If the above-mentioned film comprising tin as the main component is allowed to stand in a high-temperature and high-humidity atmosphere for a long time, because of an adhesion of water drops or other foreign substances, pinholes are formed by pitting and the bit error rate is increased, with the result that a problem arises with respect to the reliability of the medium.
Moreover, if this film comprising tin as the main component is formed on a plastic substrate such as polymethyl methacrylate or polycarbonate and recording is conducted on this recording medium, the formation of pits is incomplete and the film material is not completely removed from the laser beam-irradiated area but a slight amount thereby remains in the interiors of pits, as shown in FIG. 2. Therefore, the C/N ratio upon reproduction is unsatisfactory and the bit error rate is high.


A digital signal processor comprises a bus structure including a program bus, data bus and data input/output bus, a program memory, a program controller, an internal data memory made up of a plurality of 2-port memories for storing block data, an arithmetic operator, a DMA controller for implementing block data input/output between the internal data memory and an external data memory in parallel to an internal operation by the arithmetic operator, an address generator for generating addresses for the internal operation and DMA transfer concurrently and in parallel to the internal operation, and parallel data input/output ports for implementing parallel data communication with an external device independently of input/output operations and in asynchronous fashion. The processor executes an intricate adaptive process algorism such as image signal processing at high speed and at high throughput.

1. Field of the Invention
The present invention relates to a digital signal processor for implementing computation which is mainly intended for systems of signals.
2. Description of the Prior Art
FIG. 1 shows in block diagram a conventional digital signal processor intended mainly for audio signal processing, i.e., Digital Speech Signal Processor 1 (DSSP1) in this example described in the proceeding of symposium of the annual convention of The Institute of Electronics and Communication Engineers of Japan, Communication Section, held in 1986. In the figure, indicated by 1 is a program counter (PC) which incorporates a stack pointer for controlling the program address, 2 is a program ROM in the DSSP1, 3 is an instruction register 0 (IRO) for latching an instruction retrieved from the program ROM 2, 4 is an instruction register 1 (IR1) for latching the instruction released from the IRO 3 onto a program bus P-Bus 9, 5 is an instruction decoder for decoding the instruction held in the IR1 4, 6 is a bus interface register (BIR) for relaying immediate data placed on the P-Bus onto a data bus (D-Bus) 10, 7 is an address arithmetic unit (AAU) which incorporates three address registers for generating addresses, 8 is a page register (PR) which adds high-order 3 bits to a 9-bit address output from the AAU 7 to produce a 12-bit external RAM address, 9 is the program bus (P-Bus) for transferring instructions, 10 is the data bus (D-Bus) for transferring data separately from the P-Bus 9, 11, 12 are selectors, 13 is a data pipeline register 0 (DPR0) for receiving one input for an execution unit (will be described shortly), 14 is a data pipeline register 1 (DPR1) for receiving another input for the execution unit, 15 is an internal 2-port data memory (2P-RAM) having a 512-word capacity, 16 is a floating point multiplier (FMPY) for implementing the 12E6 floating point multiplication for the outputs of the DPR0 13 and DPR1 14, 17 is a pipeline register (P register) for latching the output of the FMPY 16, 18, 19 are selectors, 20 is a floating point arithmetic logic unit (FALU) for implementing the 12E6 floating point operation for two inputs to produce one output, 21 is a selector, 22 are accumulators 0-3 (ACCO-ACC3) each having a 4-word capacity, 23 is a loop counter (LC) for counting the number of loops in a program, 24 is a status register (SR) which indicates all statuses of the processor and controls the mode of operation, especially for setting the interrupt mode of a DMA controller 26. The connections of SR24 in FIG. 1 are omitted for simplicity of representation. 25 is a selector for selecting the outputs of the AAU 7 and DMA controller 26, 26 is the direct memory access (DMA) controller for implementing DMA transfer between serial I/O 33, 35, 37, 39 and an external RAM 32, 45 is a R/W controller for controlling data reading and writing for the external RAM, 27 and 28 are read RD and write WR signals provided by the R/W controller 45, 29 is an address register for latching the address 30 of the external RAM, 31 is a data register DR for latching data on the data bus 32 which is connected to the external RAM, 33 is SO0 for outputting serial output data 0 (34), 35 is SI0 for inputting serial input data 0 (36), 37 is SO1 for outputting serial output data 1 (38), 39 is SI1 for inputting serial input data 1 (40), 41 is an interrupt controller for analyzing the interrupt signal 42 to determine the interrupt, and 43 is a bus controller for controlling the data bus 32 connected to the external data RAM using the bus signal 44.
FIG. 2 shows an example of arrangement using two sets of DSSP1 shown in FIG. 1 for implementing a sample-by-sample process through the serial data ports. In the figure, indicated by 50 is a master processor which is the entire DSSP1 shown in FIG. 1, 52 is a request signal issued by the master processor 50 to a slave processor 51, and 53 is an acknowledge signal issued by the slave processor 51 to the master processor 50.
Next, the operation of the above conventional digital signal processor will be explained in brief. This system arangement has the separate P-Bus 9 and D-Bus 10, allowing the instruction decoder 5 to perform instruction fetching and the FMPY 16 and FALU 20 to execute internal operations concurrently. In addition, address generation by the AAU 7 takes place in parallel to these operations, thereby preventing instruction overhead from the address generation. The system has a DMA transfer function by the DMA controller between the external data bus 32 and the two serial I/O systems 33, 35 and 37, 39. Since the DMA transfer uses the D-Bus 10, the internal operation halts for a 6 machine cycle time for each word transfer during the DMA transfer cycle. The parallel processing ability of this system is summarized as follows.
(1) Address generation (primary address) by AAU 7. PA0 (2) Floating point multiplication by FMPY 16. PA0 (3) Floating point arithmetic/logic operation by FALU 20. PA0 (4) Data transfer between 2P-RAM 15 and external RAM.
(5) Data transfer between two serial I/O systems 33, 35/37, 39 and external RAM (this data transfer causes an internal operation to halt for a 6 machine cycle time for each transferred word).
The system allots one system of serial I/O 33, 35, 37, 39 to the A/D converter and another system to the transmission path, making itself suitable for arranging on a single chip a full-duplex audio codec which implements DMA transfer in units of transmission frame and buffering using an external RAM, rather than for fast processing mass data using an external memory.
The arithmetic operator constituted by the FMPY 16 and FALU 20 is capable of executing a product-sum operation, which is performed often in FIR filters and FFT (fast Fourier transformation), in one machine cycle, as in the case of a multiplier-accumulator pair described in article "Packing a single processor onto a single digital board", by Louis Schirm, Electronics, Dec. 20, 1979. Namely, this system achieves the maximum throughput when the multiply-accumulation operation is carried out continuously, and it reaches 40 MIPS (mega instructions per second) when the machine cycle is 50 ns.
However, general signal processings include other types of operations such as absolute value accumulation and differential absolute value evaluation besides the multiply-accumulation operation, in which case the FMPY 16 cannot be used, resulting in a halved throughput of 20 MIPS achieved by the FALU 20 alone.
Next, the operation of the DSSP1 multiprocessor configuration will be described in connection with FIG. 2. Serial input data of system 0 (36) and system 1 (40) entered to the master processor 50 are rendered a certain computation by the processor 50, which yields an intermediate result. The master processor 50 issues a data transfer request 52 to the slave processor 51 and, after confirming a data transfer ready 53 from the slave processor 51, transfers the intermediate result held in the DR 31 to the slave processor 51 through the data bus 30. The DR 31 is timed for latching on the basis of the RD 27 and WR 28.
Subsequently, the intermediate result processed by the slave processor 51 is transferred back to the master processor 50 using a reverse procedure and, after being rendered a final computation by the processor 50, sent to the serial data output ports 34 and 38 of system 0 and system 1.
This system arrangement is based on the anticipation of the intricate signal processing algorism which is infeasible to carry out by a single DSSP1 and the requirement of throughput which is beyond the ability of a single DSSP 1. However, the system involves the following problems. First, in case of mass data transfer by way of the data bus 30, the throughput is not improved as expected due to the overhead of data transfer control. The master and slave processors 50 and 51 must be in complete synchronism in running their programs, and if the load is concentrated to one of the processors the system throughout is determined by its maximum load. Finally, data transfer through the data bus 30 creates a bus contention with a process using the external RAM which is connected through the data bus 30, resulting in a possible significant fall in throughput.
Although these problems may easily be overcome by addition of an external control circuit, this will result in an increased hardware and lowered flexibility and the abandonment of the superiority of the signal processor in a processor-based system. Especially, image signal processing is mostly required to perform a very fast processing for mass data in a multiprocessor configuration using a video frame memory, and the above-mentioned scheme imposes a most significant problem in introducing processors in image signal processing.
As described above, the conventional digital signal processor is not always suitable for signal processings such as image signal processing, and an intentional application of this will incur an increased number of processors needed for compensating the lowered throughput and an increased hardware of external circuitry due to the increased load. As a result, it has been difficult to introduce a processor-based system to this technical field.


An apparatus and method for drilling an underground borehole is presented, wherein pressurized air may be used to discharge out of the borehole cuttings created by a cutter head. A casing may be secured to the cutter head such that the cutter head and casing may be rotatable together as a unit. The casing may have larger and smaller diameter sections. An auger may be disposed adjacent the front of the casing.

Technical Field
The invention relates generally to apparatus and methods for drilling generally horizontal boreholes. Compressed air may be used to facilitate removal of the cuttings or spoil from the borehole, and a reduced diameter casing may be used to drive rotation of a cutting head.
Background Information
Underground boring machines have been used for decades in the drilling of generally horizontal boreholes, which may include boreholes which are substantially straight and those which are arcuate for the primary purpose of avoiding or bypassing an obstacle. Often such boreholes are formed by initially drilling or otherwise forming a pilot hole of a generally smaller diameter, followed by the use of an enlarged cutting head which follows the path of the pilot hole in order to enlarge the borehole. In some cases, it may take only one pass in addition to the pilot hole to create the desired final diameter of the borehole. In other cases, additional enlarged cutting devices may be used to drill as many passes as necessary to achieve the desired diameter of the borehole.
Many of the boring machines utilize an auger which is rotated in order to force the cuttings or spoil to be removed from the borehole. Such augers may be disposed in a casing and have an outer diameter which is slightly smaller than that of the inner diameter of the casing in which it is disposed. Drilling fluid or mud is often pumped into the borehole either within a casing or external to a casing in order to facilitate the cutting process and removal of the cuttings. Drilling fluids or lubricants may involve water, bentonite or various types of polymers, etc. The use of certain types of drilling fluids may present environmental hazards and may be prohibited by environmental laws or regulations in certain circumstances. The inadvertent return of drilling lubricant, sometimes referred to as "frac-out", may be of concern when the drilling occurs, for example, under sensitive habitats or waterways. Although bentonite is non-toxic, the use of a bentonite slurry may be harmful to, for example, aquatic plants and fish and their eggs, which may be smothered by the fine bentonite particles when discharged into waterways.
As noted above, many underground boring systems utilize augers to remove the cuttings from the borehole. Such augers are typically formed in sections, which are sequentially added rearwardly as the borehole becomes longer and can accommodate additional auger sections. Given that many boreholes may be several hundred feet long, an auger of such length adds a substantial amount of weight and frictional resistance to the rotation thereof. There is a need in the art for improvements with respect to the above-noted problems.

Apparatus and method for drilling generally horizontal underground boreholes


A control lever assembly adapted for use with a powered surgical instrument which prevents the instrument from being inadvertently or accidentally activated. The assembly 10 includes a depressible control lever 20 for controlling the action of the instrument and a second safety lever or latch 30 which engages the trigger pin 6 of instrument only when selectively positioned with respect to control lever 20. Control lever 20 is secured to cutting device 2 by a mounting bracket 12. Safety latch 30 is pivotally carried by control lever 20 for shiftable movement between a safety position and an operational position. In the operational position, safety latch 30 engages trigger pin 6 when control lever 20 is depressed. Safety latch 30 cannot be switched from its safety position to its operational position when control lever 20 is depressed; therefore, the instrument is "locked-out" and cannot be inadvertently activated even when control lever 20 is depressed. Safety latch 30 can only be manually shifted from the safety position to the operational position when control lever 20 is released, which ensures safe handling of the instrument.

Hand held powered surgical instruments are well known in the medical field. In general, the operation of such instruments are controlled by depressing a trigger pin which extends from the body of the instrument. Most conventional hand held instruments include an external control lever for manually controlling the downward pressure applied to the trigger pin thereby controlling the operation of the instrument. The control lever allows the instrument to be easily activated and manipulated with one hand. Since the control lever is exposed, incorporating a safety mechanism into the control lever is desirable to prevent the instrument from being inadvertently activated during handling. Ideally, a safety mechanism should be operable with one hand and cooperate with the control lever.

Safety device for a powered surgical instrument