Methods for increasing the efficiency of target tissue penetration of an adeno-associated virus (AAV) vector in a patient are provided. In some aspects, the methods involve inhibiting the interaction of the serum protein galectin 3 binding protein (G3BP) with AAV vector. Further provided are methods for reducing tissue distribution of a virus or for neutralizing a virus harbored by an organ destined for transplant, or newly transplanted, by administering a composition comprising G3BP.

Galectin-3 binding protein (G3BP), also known as 90-kDa Mac-2 binding protein, was initially identified and characterized in breast cancer cells and in human milk [see, Koths K. et al. (1993) J. Biol. Chem. 268:14245-14249], and is a heavily N-glycosylated secreted protein of about 90 kDa. G3BP is known to interact with Galectin-3, Galectin-1 and Galectin-7 [see, Inohara et al. (1996) Cancer Research 56:4530-4534; Tinari, N. (2001) Int J Cancer 91:167-172; Liu, F T et al. (2005) Nat Rev Cancer 5:29-41]. Further, G3BP is elevated in the serum of subpopulations of patients with various types of cancer [see, Iacobelli S. et al. (1986) Cancer Res. 46:3005-3010; Iacobelli S. et al. (1988) Breast Cancer Res. Treat. 11:19-30; Iacobelli S. et al. (1994) Br. J. Cancer 69:172-176; Scambia, G. et al. (1988) Anticancer Res. 8:761-764], and in patients infected with human immunodeficiency virus (HIV) [see, Natoli et al. (1991) J. Infect. Dis. 164:616-617; Natoli et al. (1993) J. AIDS 6:370-375; Iacobelli, S. et al. (1991) J. Infect. Dis. 164:189; Briggs, N.C. et al. (1993) AIDS Res. Hum. Retroviruses; 9:811-816; Longo, G. et al. (1993) Br. J. Haematol. 85:207-209]. G3BP also has stimulatory effects on cells of the immune system, such as NK cells and lymphokine-activated killer cells [see, Ullrich, A. et al. (1994) J. Biol. Chem. 269:18401-18407]. A role for G3BP in inhibiting the spread of viruses within a host's body, however, has not been previously described.
While the immune system is designed to fight and, ideally, inhibit the spread of viral infection, certain viruses are especially adept at evading or overcoming the immune response. Moreover, immunocompromised individuals, such as those taking immunosuppressant drugs to prevent rejection of a transplanted organ, or those infected with HIV, are particularly susceptible to viral infection. While anti-viral medications are currently available for some viruses, many viruses rapidly mutate and become resistant to these drugs, and for other viruses, no such drugs are available [see, Barth R E et al. (2010), Lancet Infect Dis; 10:155-66; Marcelin A G et al. (2009), Curr Opin HIV AIDS; 4:531-537]. Therefore, new compositions and methods for preventing, delaying, or limiting the severity of viral infection in an individual are needed.
In the case of gene therapy, which is a technique for correcting a defective gene responsible for disease development by replacing or introducing mutations into the defective gene, it is actually desirable to enhance the spread of a virus (in the form of a vector) to organs and tissues. Specifically, viral vectors, such as those derived from adeno-associated virus (AAV), are commonly used to deliver a corrective gene to target tissues, and inhibiting or delaying the spread of such vectors to target tissues severely limits the efficacy of the vector. Currently, a number of vectors that would otherwise be useful for gene therapy, including AAV vectors in particular, are plagued by low efficiency, and methods for increasing their efficiency are needed.
AAV is an attractive candidate for generating viral vectors for gene therapy, because it is a small, single-stranded DNA virus that infects humans and certain other mammalian species, including dogs, but does not cause infection or elicit a strong host immune response. There are 11 known serotypes of AAV, AAV1-AAV11. AAV expresses the capsid proteins VP1, VP2 and VP3, which are involved in and are thought to be required for AAV infection of target tissues. The molecular weights of these proteins are 87, 72, and 62 kDa, respectively [Jay F T et al. (1981) PNAS; 78:2927-31]. Given the importance of capsid integrity on infectivity, all capsid proteins are likely required for infection. VP2 is especially important, as AAV capsid can only form in its presence [Ruffing et al. (1992) Journal of Virology; 66:6922-6930].
Clinical trials evaluating the safety and efficacy of AAV-vector based gene therapy for a broad variety of conditions are currently underway. These conditions include, for example, Pompe disease (caused by an acid alpha-glucosidase deficiency), inflammatory arthritis, Lebers Congenital Amaurosis (caused by RPE65 mutations), Canavan disease, childhood blindness (caused by mutations in RPE65), alpha 1-antitrypsin deficiency, heart failure, hemophilia, limb girdle muscular dystrophy type 2D, lipoprotein lipase deficiency, cystic fibrosis, Parkinson's disease, Duchenne muscular dystrophy, late infantile neuronal ceroid lipofuscinosis, Alzheimer's disease, and cutaneous B cell lymphoma [see, Journal of Gene Medicine website at http://www.wiley.co.uk/genetherapy/clinical/; http://www.abedia.com/wiley/images/0912vectors.jpg; Rodino-Klapac et al, Neurology (2008); 71:240-247; Towne et al, Gene Ther. (2010); 17: 141-146].
For effective use in gene therapy to treat conditions such as those described above, an AAV vector must achieve systemic distribution throughout target tissues (i.e., "tissue distribution"). One disadvantage of using AAV vectors for gene therapy is that many individuals are already seropositive for AAV. For instance, this value varies from 5% for AAV5 to 60% for AAV2 (these values are known for AAV1, 2, 5, 6, 8, 9) [see, Boutin et al., Hum Gene Ther. (2010) January 22. [Epub ahead of print]]. Serum antibodies in this population bind to and sequester AAV in the blood. The resultant antibody-AAV complexes are cleared by the liver, thereby preventing systemic distribution of the vector.
Even in gene therapy patients who are seronegative for AAV, however, efficiency of AAV penetration in target tissues is low, and high amounts of AAV vector must be administered to the patient in order for the dose of AAV to effectively achieve systemic distribution, including distribution into target tissues. The requirement for high concentrations of AAV vector poses a significant disadvantage for its use in gene therapy, since vector overloading can be toxic under certain circumstances. Furthermore, such high titres of vector can be difficult to produce. (See, Virag et al., Hum Gene Ther. (2009) 20:807-817).
As described above, there remains a need to identify methods and compositions for increasing the efficiency of AAV penetration into target tissues and to identify methods and compositions for inhibiting the spread of harmful viral infections. The present invention provides such methods and compositions.

Methods of increasing efficiency of vector penetration of target tissue

CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE

UNIVERSITÉ PIERRE ET MARIE CURIE (PARIS 6)

INSTITUT NATIONAL DE LA SANTÉ ET DE LA RECHERCHE MÉDICALE


A portable terminal 20 according to the present invention is provided with an electronic book coupon storage 22, a book data receiver 24, an electronic book coupon deductor 25, and a book data decryptor 26. The electronic book coupon storage 22 stores an electronic book coupon used in acquisition of book data containing a plurality of page data units, along with a decryption key used in decryption of the plurality of page data units. The book data receiver 24 receives the book data from an electronic book providing server 30. The electronic book coupon deductor 25 deducts an electronic worth equivalent to a price according to page data requested to be readout, from the electronic book coupon. The book data decryptor 26 decrypts the page data in steps of one page data unit by use of the decryption key in conjunction with the deduction of the electronic worth.

1. Field of the Invention
The present invention relates to a communication terminal, a portable terminal, a circulating server, a providing server, an electronic book distributing method, and an electronic book distributing program.
2. Related Background Art
In recent years, electronic books (also called e-books (trademark)), which are superior in portability and searchability to books of paper media and which can contain records of sound, are in practical use. The electronic books are digitized books which can be purchased and read by use of such terminals as personal computers and PDAs (Personal Digital Assistances). The electronic books are roughly classified into two types depending upon provided forms, a package type in which book data is stored in a recording medium such as a CD-ROM, an FD, or the like, and a network type in which book data is transmitted and received through networks such as the Internet.
Particularly, the following operation form is the mainstream about the electronic books of the network type. Namely, a user of a portable terminal purchases an electronic book coupon from a circulating server managed by an issuer of the book coupon. Then the user uses the electronic book coupon thus purchased to download a desired electronic book from a providing server managed by a publisher of the electronic book, into the portable terminal. The portable terminal displays the electronic book thus downloaded, whereby the user can read it.

Communication terminal, portable terminal, circulating server, providing server, electronic book distributing method, and electronic book distributing program


The invention is a self-terminating helper flip-flop buffer circuit pertinent to a dynamic random access memory (DRAM) or static random access memory (SRAM) device. The invention turns off a device which is sourcing current to pull the data line low. The device is turned off when the potential on the low data line has transitioned to the trip point of the output data latch. The circuit of the invention senses the transition and provides the self terminating signal to the current source.

High density dynamic random access memorys (DRAMs) and static random access memorys (SRAMs) have long data lines for routing the memory cell information from the memory array to the output logic and output drivers at the periphery of the chip. These long data lines have large parasitic capacitances which limit the maximum operating frequency of the device. One method of improving the speed of the device is to reduce the length of the data lines by subdividing the memory array into smaller sections. However, this method is not always practical due to limitations in die size, packaging constraints, and other architectural layout limitations.
Many techniques have been employed for sensing the differential signal developed on the DRAM digit lines, amplifying the signal, and transmitting it to the output buffers. One method commonly used in DRAMs is to sense the signal with n and p-channel sense amplifiers, drive this differential potential to the end of the array, and amplify the differential potential with DC sense amplifiers located at the end of the array. The output of the DC sense amplifiers are used to drive the output logic located in the chip periphery.
With this approach the data lines develop a differential potential relatively slowly due to the low drive of the sense amp and the large RC time constant of the digit line, I/O line and data line combination. Specifically, the n and p-channel sense amplifiers are designed to have low drive capability in order to reduce power dissipation, since as many as 256 sense amps are turned on at once (the entire row). These sense amps drive the data lines through a column decode transistors 1 and an I/O line-to-data line multiplexer transistors 5, see FIG. 1. These transistors 5 have a drain-to-source resistance which increases the RC time constant of the circuit. Further, the capacitive load of the I/O lines 10 and data lines 11 combination is relatively large due to the number of column decode transistors 1 connected to the I/O lines 10, and due to the long lengths of data lines 11.
Another approach that is used in sensing the potential of the I/O lines is the addition of a helper flip-flop. With a helper flip-flop, the I/O lines are allowed to develop sufficient differential potential prior to clocking the flip-flop with an enable signal. While enabled, the helper flip-flop uses positive feedback to pull the true and complement output signals towards opposite supply potentials, thus amplifying the input signal. The large level differential output potential can be used to drive the input of a buffer circuit for driving the large capacitive load of the data lines. Sometimes, an additional helper flip-flop is used at the end of the data lines.
The advantage of a helper flip-flop is that the data lines are buffered from the I/O and digit lines, and a lower output impedance buffer circuit is used to drive the capacitive data lines. The disadvantage of this approach is that adequate signal must be developed prior to clocking the flip-flop to ensure that the output transitions to the correct state. Thus, the flip-flop must be clocked each time a new memory bit is accessed.
With either architecture, DC sense amp or helper flip-flop, the I/O and data lines are equilibrated and precharged to some operating point prior to turning on the column decoder gate and transferring the digit line differential potential. This is done to improve the speed, because the I/O and data lines now transition from midpoint to new state instead of from old state to new state. With a DC sense amp, the I/O and data lines are precharged to a potential compatible with the quiescent operating point of the amplifier, usually on the order of 0.6 V.sub.cc. With the helper flip-flop the I/O and data lines are usually precharged to V.sub.cc, and the output changes state when one of the data lines (true or complement) transitions to the opposite state, ground in this case.
With the helper flip-flop some speed is lost and some power is dissipated in each access cycle, since the data line transitions from V.sub.cc to ground and is precharged back to V.sub.cc prior to transitioning back to ground. Since the data lines have a large capacitive load, it takes significant time for the lines to transition between each power supply level. Also, power is dissipated in precharging and discharging the capacitances.
The output of the helper flip-flop usually drives a data latch which is used to store the data result while the data lines precharged. The latch 15 is shown in FIG. 2. The latch is constructed in a manner such that the latch holds the previous data when the data lines are both high, and the latch is set or reset when one of the data lines transitions low. The input of the latch can be designed to have a high trip point to improve and reduce the time required to transition to a new state.
FIG. 3 shows the schematic of a helper flip-flop buffer circuit. Transistors 20 and 25 comprise the cross-coupled differential transistor pair and transistor 30 is the current source for the helper flip-flop 35. The helper flip-flop 35 is clocked by a strobing signal, ENNSA, available at terminal 40. Transistors 45, 50, and 55 are used to precharge and equilibrate the helper flip-flop 35 to V.sub.cc. Transistors 60 and 65 are pass devices used to isolate the I/O lines 70 from the flip-flop 35 just prior to strobing the flip-flop 35. Transistors 75, 80, and 85 are used to precharge and equilibrate the data lines 90 and 95 to V.sub.cc. The buffer section 96 comprises differential pair transistors 100 and 105 and comprises the current source transistor 110. Capacitors 115 and 120 have been used to model the data line parasitic capacitance load.
FIG. 4 shows a typical timing sequence for the schematic of FIG. 3. The I/O lines 70 have been initially precharged to V.sub.cc (5v) by an I/O line precharge circuit not shown. During the precharge time the helper flip-flop internal nodes 111 and 112 and data lines 90 and 95 are precharged to V.sub.cc by a low CEQ* signal at terminal 113; the flip-flop and buffer section 96 is turned off since the signal at the ENNSA terminal 40 is low. At this time, the helper flip-flop 35 is also isolated from the I/O lines 70 by a high HFFISO* signal at terminal 114.
Differential potential is allowed to develop on the I/O lines at the start of an access cycle. At this time the equilibration is released (CEQ* goes high) and the helper flip-flop is connected to the I/O lines through the pass devices 60 and 65 (HFFISO* goes low). A small differential potential then develops on the helper flip-flop internal nodes 111 and 112. The potentials on internal nodes 111 and 112 are referred to as HFF and HFF* respectively. After sufficient potential has developed, the helper flip-flop 35 is isolated from the I/O lines (HFFISO* goes high) and ENNSA goes high which enables the buffer section 96. The internal flip-flop nodes 111 and 112 rapidly separate in potential due to the positive feedback of the helper flip-flop 35. These signals then drive the buffer section 96 which causes one of data lines 90 and 95 to be pulled to a low state, in this case complimentary data line (DL*) 95. After the data line has reached its ground potential, the helper circuit flip-flop 35 can be disabled (ENNSA goes low), and I/O lines 70 and data lines 90 and 95 can be precharged for the next access cycle. In the figure, data line (DL) 90 starts to momentarily go low by 1.5 volts; however, this is due to the equilibrate device. After sufficient precharge time, both data lines 90 and 95 will return to V.sub.cc.
The speed of an access cycle can be improved in a helper flip-flop design by only allowing the data lines to transition to a predetermined margin past the trip point of the data latch, as opposed to transitioning all the way to ground. Cycle time is improved because the data lines take less time to precharge from this level. A data line clamping circuit can be used for this purpose; however, power is dissipated in the clamping circuit.
FIG. 5 shows the same schematic as FIG. 3 with diode clamps 200 and 205 added to the data lines to limit their potential swing. The clamps can be sized appropriately to clamp the potential at the desired level. FIG. 6 shows the timing for this circuit which is identical to FIG. 2 except for the data line potentials. Note that the potential of complimentary data line 95 only reaches 2.5v due to the clamps, and therefore precharges back to V.sub.cc faster. If we assume that the trip point of the output latch is at 3v, then the output latch will switch later than in the previous circuit. This is due to the exponential transition of the data line, where the data line now exponentially approaches 2.5v instead of Ov. This is because the pull-down drive current of transistor 100 or 105 is opposed by the clamping pull-up current of transistor 200 or 205, respectively. In this case since the trip point is closer to the exponential final value, it takes longer for complimentary data line to reach the trip point potential. Further, more power is dissipated in this circuit since a DC current path exists from Vcc to ground via transistors 200, 100, and 110 or transistors 205, 105, and 110.
What would be most desireable is to have a signal that approaches ground at the same rate as in the circuit of FIG. 1, but stops abruptly, not exponentially, at some intermediate potential level. Further, it is desired to achieve this signal waveform without introducing more power dissipation as in the circuit of FIG. 5 comprising the diode clamps. The described invention accomplishes these goals, and thereby improves on the prior art.


A MONOS nonvolatile memory of a split gate structure, wherein writing and erasing are performed by hot electrons and hot holes respectively, is prone to cause electrons not to be erased and to remain in an Si nitride film on a select gate electrode sidewall and that results in the deterioration of rewriting durability. When long time erasing is applied as a measure to solve the problem, drawbacks appear, such as the increase of a circuit area caused by the increase of the erasing current and the deterioration of retention characteristics. In the present invention, an Si nitride film is formed by the reactive plasma sputter deposition method that enables oriented deposition and the Si nitride film on a select gate electrode sidewall is removed at the time when a top Si oxide film is formed.

It becomes possible to realize a highly functional semiconductor device by consolidating a nonvolatile semiconductor memory cell with a logic semiconductor device on the same silicon (Si) substrate. Such highly functional semiconductor devices are widely used as built-in microcomputers for industrial machines, home appliances, vehicle-installed devices, and others.
A consolidated nonvolatile memory is generally used by storing and retrieving programs required by a microcomputer as needed. As such a nonvolatile memory as to have a cell structure suitable for being consolidated with a logic semiconductor device, there is a memory cell having a split gate structure and comprising a select MOS transistor and a memory MOS transistor.
As methods for retaining electric charge in a memory MOS transistor which is prevailing in consolidated use since the area of peripheral circuitry for the control of memory can be reduced by the adoption of such a structure, there are the floating gate method wherein electric charge is stored in electrically conductive polycrystalline silicon isolated electrically and the MONOS method wherein electric charge is stored in an insulator film, such as an Si nitride film, having the function of storing electric charge.
Either of such electric charge retaining methods is configured so that the region where electric charge is stored is covered by an Si oxide film excellent in electrical isolation. However, the MONOS method has some advantages that: it allows discrete storage since electric charge is stored in an insulator film; it facilitates prediction of reliability since it does not see the radical shortening of charge retention time caused by defects of an Si oxide film; and it has a simple memory cell structure and therefore it is easily consolidated with logic gates. In addition, since the MONOS method does not see the radical shortening of charge retention time caused by defects of an Si oxide film, hot-hole erasure which is likely to cause damage to an Si oxide film can be adopted, thus erasing time can be shortened by leaps and bounds, and resultantly the MONOS method gathers attention in recent years. Here, hot-hole erasure is described later in detail but briefly it is the method for erasing hot electrons stored in an Si insulator film as recorded information by inducing hot holes in a memory cell and neutralizing and erasing the electrons as the stored information.
As a split gate structure particularly suitable for miniaturization, there is a structure wherein a memory MOS transistor is formed with a sidewall by utilizing self-alignment (hereunder referred to as "self-aligned split gate structure"), (for example, refer to Patent documents 1 to 3).
In the case of a MONOS memory adopting such a self-aligned split gate structure, the gate length of a memory MOS transistor can be smaller than the minimum resolution size of lithography and therefore it has the advantages that operation current can be increased (operation frequency increases) and the area of a memory cell can largely be fractionized. The structure and operation of a conventional MONOS memory cell are hereunder explained briefly on the basis of FIG. 15.
Such a nonvolatile memory is composed of two MOS transistors; a memory MOS transistor Q1 that composes a storage node and a select MOS transistor Q2 that selects the storage node and retrieves information. The diffusion layer (source region) 406a of the select MOS transistor Q2 is connected to a common source line and a select gate electrode 403 is connected to a word line. Meanwhile, the diffusion layer (drain region) 406b of the memory MOS transistor Q1 is connected to a bit line and a memory gate electrode 405 is connected to a memory gate line.
The gate insulator film 404 of the memory MOS transistor Q1 is composed of a film of a three-layered structure; for example, from the surface of an Si substrate 401 in order, an Si oxide film (the first-layered film) 404a, an Si nitride film (the second-layered film) 404b and another Si oxide film (the third-layered film) 404c.
With regard to the thickness of the gate insulator film, each of the first-layered film 404a, second-layered film 404b and third-layered film 404c is about 5 to 15 nm.
The gate insulator film 404 of the memory MOS transistor Q1 is formed after the gate electrode 403 of the select MOS transistor Q2 is formed and therefore it is formed also on the sidewall of the select gate electrode 403.
The thermal oxidation method is used for the formation of the first-layered Si oxide film 404a. The low-pressure thermal CVD method which is excellent in step coverage is used for the formation of the second-layered Si nitride film 404b, and the method of using dichlorosilane (SiH2Cl2) and ammonia (NH3) as the material gas is generally employed. For the formation of the third-layered Si oxide film 404c, either of the thermal oxidation method and the low-pressure thermal CVD method is commonly used and, generally speaking, the thermal oxidation method is dominantly used.
Writing operation is carried out by: applying prescribed voltages to the diffusion layer (source region) 406a and gate electrode 403 of the select MOS transistor Q2 and thus activating the select MOS transistor Q2; and simultaneously applying prescribed voltages to the diffusion layer (drain region) 406b and gate electrode 405 of the memory MOS transistor Q1. For example, the voltages of 0 V, 1 to 2 V, 3 to 5 V and a high voltage of 8 to 10 V are applied to the source region 406a, the gate electrode 403 of the select MOS transistor Q2, the drain region 406b and the gate electrode 405 of the memory MOS transistor Q1, respectively.
Under such voltage conditions, a high electric field is imposed on the boundary region between the select MOS transistor Q2 and the memory MOS transistor Q1, and resultantly hot electrons of large energy are generated in the Si substrate 401. Some of the hot electrons are injected to the side of the memory gate electrode 405 to which a high voltage is applied. At the time, most of the hot electrons are trapped in the Si nitride film 404b that constitutes a part of the gate insulator film of the memory MOS transistor Q1. Such an electron injection method is generally called the source side hot-electron injection method or the source side injection method.
Erasing operation is carried out by the method of: applying a negative bias to the memory gate electrode 405 of the memory MOS transistor Q1 and a positive bias to the diffusion layer 406b (drain region); generating hot holes by using band-to-band tunneling (BTBT); and injecting the hot holes into the Si nitride film 404b (hot-hole erasing). For example, erasing is carried out by applying 5 to 7 V to the drain region 406b, −9 to −11 V to the gate electrode 405 of the memory MOS transistor Q1, and 0 V or no voltage application to the source region 406a and the gate electrode 403 of the select MOS transistor Q2.
Retrieving operation is carried out by retrieving recorded information in compliance with whether a prescribed current is fed or not in accordance with the state of the threshold voltage of the memory MOS transistor Q1 when the select MOS transistor Q2 is activated.    [Patent document 1] JP-A No. 74389/1999    [Patent document 2] JP-A No. 46002/2003    [Patent document 3] JP-A No. 237540/2002
The problems of the MONOS memory of a split gate structure shown in FIG. 15 are explained on the basis of figures. FIGS. 16 and 17 are views obtained by enlarging the region A of FIG. 15.
As described above, the region where hot electrons are generated in the Si substrate 401 at the time of writing is located underneath the vicinity of the region where the select gate electrode 403 of the select MOS transistor Q2 and the memory gate electrode 405 of the memory MOS transistor Q1 are electrically separated. Some of the hot electrons generated from the position are injected toward the edge of the gate electrode 405 by the gate electric field of the memory MOS transistor Q1. Most of the injected hot electrons are trapped in the Si nitride film 404b having a large trapping sectional area and resultantly writing is carried out.
As shown in FIG. 16, in the event of the aforementioned writing, hot electrons are injected in the direction of the arrow while extending laterally and therefore some of the hot electrons are injected also into the sidewall region of the gate electrode 403 of the select MOS transistor Q2, in other words, the vertical region of the L-shaped Si nitride film 404b (the direction perpendicular to the Si substrate). Further, it is estimated that the distribution of the trapped electrons further expands by the influences of: the internal electric field in the Si nitride film 404b caused by the trapped electrons; and a high temperature environment of about 150° C.
Meanwhile, in the event of the injection of hot holes for erasing, hot holes are injected in the direction of the arrow from one end of the drain 406b of the memory MOS transistor Q1 as shown in FIG. 17. The hot holes generated in the high electric field region at the end of the drain 406b are injected into the Si nitride film 404b while being influenced by the electric field of the memory gate electrode 405 and slightly expanding toward the side of the select MOS transistor Q2.
The extension of the hot-hole injection in the lateral direction depends on injection conditions and is estimated to be 50 to 80 nm. As shown in FIG. 17, electrons existing in the region into which positive holes are injected are erased in microseconds, but the electrons existing outside the positive hole injected region has a very small positive hole density and therefore some electrons are unerased and remain. The amount of unerased electrons increases as the frequency of rewriting increases, and therefore the drawback here is that a prescribed threshold voltage cannot be secured even though erasing of electrons is carried out for the last time.
In order to avoid unerased electrons from remaining, it is necessary either to further shorten the gate length (Lmg) of the memory MOS transistor Q1 or to prolong the erasing time considerably. However, if Lmg is shortened, punch through occurs. For that reason, the lower limit of Lmg is about 60 nm.
In contrast, if the hot-hole injection time is prolonged, the following harmful effects appear: (1) the area of the charge pump power supply circuit for securing supply current increases, (2) the bottom gate oxide film 404a deteriorates and the charge retention time decreases, and (3) positive holes accumulate in the Si nitride film 404b in the vicinity of the drain 406b and the generation efficiency of hot holes lowers.

Nonvolatile semiconductor memory device and manufacturing method thereof


A needle-syringe for inserting a guidewire G in a patient comprises a barrel 10 and a hollow nozzle 15 opening into the interior of the barrel 10. It comprises a plunger 11 slidably mounted in the barrel 10 and a needle holder 14 slidably mounted in the longitudinal cavity of the plunger 11. A hollow guide member is mounted between the proximal ends of the needle holder 14 and the plunger 11 for guiding a guidewire G from the proximal end of the plunger 11 to the proximal end of the needle holder 14. The needle holder 14 includes a valve member for passing a guidewire G through the needle holder 14 while preventing blood from flowing between the interiors of the needle holder 14 and the hollow guide member. The guide member engages and retracts the needle holder 14 in response to relative rotational movement between the barrel 10 and the needle holder 14.

A hypodermic needle has many applications in modern medicine. One application is to fit the hypodermic needle onto a syringe and to then insert the needle into a person's body for intramuscular, subcutaneous, or intravenous injection of medications. A hypodermic needle entering into a patient's body is invariably contaminated by the patient's blood and body fluids. Following use of the needle, the needle presents a risk to physicians, nurses, and other health care personnel because the needle might transmit an infection or disease to such personnel if it were to accidentally puncture them. Thus, health care personnel are in constant danger of contracting infections and diseases, some of which may be deadly. Other potential victims of accidental needle punctures include sanitation workers which later dispose of garbage containing the hypodermic needle. The diseases which may be transmitted by a contaminated hypodermic needle include Immune Deficiency Virus, Hepatitis, Rabies, Kure, Encephalitis, and Arbor viruses. The outcome of contracting one of these diseases is often fatal because there are no known cures for any of these diseases. Often a needle puncture in a person's skin is so trivial that it remains unrecognized until the person becomes seriously ill.
The problem of suffering accidental needle punctures is well recognized. As a result, enormous inventive effort has been devoted to concealing the sharp needle point of hypodermic needles.
The deep-seated central veins, such as subclavian, jugular and femoral veins as well as arteries can only be accessed by negotiating a guidewire, through the puncturing needle, after disconnecting the syringe. The blood gushing out from the needle interferes with the visibility and insertion of the guidewire inside the needle. The blood also contaminates the area of operation and makes the blind insertion procedure even more difficult. The risks of needle stick are further multiplied by free sharp objects, scattered in a limited field. The present invention permits the insertion of the guidewire through the plunger itself without removing the syringe from the needle, as well as making the procedure essentially bloodless. It also avoids the needle puncture by retracting the needle even before it comes out of the patient's body.

Needle-syringe assembly for guidewire insertion


The invention provides polyisocyanates containing isocyanate groups from 1,4-diisocyanato-2,2,6-trimethylcyclohexane, having a trimer fraction of more than 80% by weight and an NCO content of at least 19.3%.

1. Field of the Invention
The invention relates to a novel polyisocyanate from 1,4-diisocyanato-2,2,6-trimethylcyclohexane (TMCDI) which contains isocyanurate groups, to a process for the preparation, and to the use.
2. Discussion of the Background
Aliphatic and cycloaliphatic diisocyanates are widely employed in high-grade light-and weather-stable polyurethane coatings. For many applications, such as for trimerization, for example, it is advantageous for the two isocyanate groups to differ in reactivity. By virtue of this so-called selectivity the fraction of unwanted oligomers (pentamers, heptamers, nonamers, etc.) is reduced and the resulting products (polyisocyanates containing isocyanurate groups) have higher NCO contents, lower viscosities and improved technical processability.
Hexamethylene diisocyanate (HDI) exhibits no selectivity whatsoever and so the corresponding polyisocyanate containing isocyanurate groups has a high unwanted oligomer fraction. Isophorone diisocyanate (IPDI), on the other hand, is selective owing to the different stearic environment of the two isocyanate groups, but trimerization under the same conditions leads to relatively low unwanted oligomer contents of approximately 35% by weight and a trimer fraction of approximately 65% by weight.
The object was to find a trimeric isocyanate having a higher NCO content and improved, lower viscosity. This object has been achieved by the trimerization product of TMCDI, with a trimer fraction of more than 80% by weight and an NCO content of at least 19.3% by weight of the trimerization product.
It has surprisingly been found that 1,4-diisocyanato-2,2,6-trimethylcyclohexane (TMCDI), a readily available cycloaliphatic diisocyanate (J. Appl. Polym. Sci. 1994, 54(2), 207-218; EP 0 945 427 A1) is particularly suited to trimerization. For a given conversion, the unwanted oligomer content of the resulting polyisocyanates containing isocyanurate groups is distinctly lower than in the case of polyisocyanates based on IPDI and containing isocyanurate groups, and the NCO content is distinctly higher.
The invention provides polyisocyanates containing isocyanurate groups from 1,4-diisocyanato-2,2,6-trimethylcyclohexane, having a trimer fraction of more than 80% by weight preferably more than 90% by weight and an NCO content of at least 19.3%, preferably at least 19.6% by weight.
The invention further provides a process for preparing polyisocyanates containing isocyanurate groups from 1,4-diisocyanato-2,2,6-trimethylcyclohexane, having a trimer fraction of more than 80% by weight, preferably more than 90% by weight, and an NCO content of at least 19.3%, preferably at least 19.6% by weight, by reacting TMCDI in the presence of at least one trimerization catalyst at from 70 to 150xc2x0 C.
1,4-Diisocyanato-2,2,6-trimethylcyclohexane, referred to below simply as TMCDI, may be converted into a polyisocyanate containing isocyanurate groups by trimerization in the presence of appropriate catalysts. For this purpose, a catalyst is added to TMCDI at room temperature and the system is heated at 130xc2x0 C. After twenty minutes, depending on the amount of catalyst, the reaction has progressed to a conversion of approximately 30-60% and is terminated either thermally or by adding an acid. Excess diisocyanate is distilled off at 150xc2x0 C. and 0.1 mbar in a short-path evaporator. The resulting polyisocyanates containing isocyanurate groups have an unwanted oligomer fraction of 8-20% by weight (trimer fraction 92-80% by weight) and an NCO content of 19.3-20.0% by weight.
Non-limiting examples of suitable trimerization catalysts are quaternary ammonium carboxylates, alkali metal and alkaline earth metal salts of carboxylic acids, trialkylphosphines or quaternary ammonium carbonates or amino silane compounds. Trioctylmethylammonium 2-ethylhexanoate, for example, is particularly suitable, and may be prepared from the corresponding chloride by the method described in more detail in U.S. Pat. No. 5,691,440.
TMCDI-based polyisocyanates containing isocyanurate groups, possibly in blocked form, represent valuable starting materials for preparing polyurethane plastics by the isocyanate polyaddition process, as base materials for coatings, and especially for preparing one- or two-component polyurethane coating materials.
Suitable blocking agents are known within isocyanate chemistry, examples being ethyl acetoacetate, diisopropylamine, methyl ethyl ketoxime, diethyl malonate, E-caprolactam, 1,2,4-triazole, and 3,5-dimethylpyrazole.
Having generally described this invention, a further understanding can be obtained by reference to certain specific examples which are provided herein for purposes of illustration only and are not intended to be limiting unless otherwise specified. The examples which follow are intended to illustrate, but not restrict, the invention:
Preparation of a polyisocyanate containing isocyanurate groups from 1,4-diisocyanato-2,2,6-trimethylcyclohexane.
292 g of 1,4-diisocyanato-2,2,6-trimethylcyclohexane were introduced into a reaction vessel, 1.46 g of trioctylmethylammonium 2-ethylhexanoate were added, and the system was heated at 130xc2x0 C. under insert gas and with stirring. After 20 minutes, the temperature was raised briefly to 150xc2x0 C. and the system was then cooled (NCO content: 31.3%, 45% conversion). Excess TMCDI was separated off on a short-path evaporator at 150xc2x0 C. and 0.1 mbar. The demonomerized product had an NCO content of 19.8% and an unwanted oligomer fraction of 33% (trimer fraction 92%) (gel permeation chromatography (GPC), super-fluid chromatography (SFC)).

1,4-Diisocyanato-2,2,6-trimethylcyclohexane polyisocyanates containing isocyanurate groups, a process for the preparation and use


Embodiments provide a system, method, apparatus, means, and computer program code that allow multiple annotations to a document to be created and that distinguish between the annotations made by different people. The people may view documents, exchange ideas and messages, etc. via a server or conference/collaboration system at different times and/or without being in direct communication with each other. In such an off-line collaboration mode, the people may want to add listen to, view, or add annotations regarding one or more documents. The methods and systems described herein allow users to follow the trail of annotations regarding a document and to distinguish between the voice or other audible annotations created by other people.

The development of various voice over IP protocols such as the H.323 Recommendation and the Session Initiation Protocol (SIP) has led to increased interest in multimedia conferencing. In such conferencing, typically, a more or less central server or other device manages the conference and maintains the various communications paths to computers or other client devices being used by parties to participate in the conference. Parties to the conference may be able to communicate via voice and/or video through the server and their client devices.
Instant messaging can provide an added dimension to multimedia conferences. In addition to allowing text chatting, instant messaging systems such as the Microsoft Windows Messenger™ system can allow for transfer of files, document sharing and collaboration, collaborative whiteboarding, and even voice and video. A complete multimedia conference can involve multiple voice and video streams, the transfer of many files, and much marking-up of documents and white boarding.
Participants in the multimedia conference or collaboration effort as well as other users may want to provide a voice, text, graphical, or other type of annotation regarding a document used in the conference or collaboration, their thoughts regarding the conference or collaboration effort, etc. The annotation may be provided back to other participants in the conference or collaboration effort for further review. As such, there is a need for a system and method for allowing multiple annotations to co-exist while distinguishing between the annotations made by different participants or other users.

System and method for indicating an annotation for a document


Systems, methods and apparatus for monitoring soil properties and applying fertilizer during a planting operation. Various sensors are disposed in ground engaging components for monitoring soil properties. The ground engaging components may have structure for opening a side trench in the sidewalls of the seed trench and may include liquid application conduits for injecting liquid into the sidewalls of the resulting side trenches.

In recent years, the availability of advanced location-specific agricultural application and measurement systems (used in so-called "precision farming" practices) has increased grower interest in determining spatial variations in soil properties and in varying input application variables (e.g. planting depth) and fertilizer and other liquid applications in light of such variations and at the appropriate location during the planting operation. However, the available mechanisms for measuring soil properties are not effectively locally made throughout the filed or not made at the same time as an input operation (e.g. planting). Additionally, commercial solutions for applying liquid have included applying liquid on top of seeds in the planting trench, which may cause deleterious effects such as "burning" (i.e., over-fertilizing) seed. Other liquid application solutions have included opening a separate trench in the soil surface (disposed between the planting trenches opened by the row unit) and depositing liquid in the separate vertical trench, which may result in underutilization of applied fertilizer.
Thus there is a need in the art for a method for monitoring soil properties during an agricultural input application and for effectively applying liquid during the planting operation.

This patent is subject to a terminal disclaimer.

Systems, methods, and apparatus for soil and seed monitoring


An active composite variable damping rotational control device includes a variable damping module and a power module. The variable damping module includes a magnetorheological fluid tank and a rotational inertia wheel. The rotational inertia wheel is arranged in the magnetorheological fluid tank fully filled with magneorheological fluid. The power module includes a device tubular cavity, a driver, an encoder and a speed changer. The driver is fixed on the inner wall of the device tubular cavity. The driver, the encoder and the speed changer are coaxial. A driving shaft of the driver passes through the speed changer and extends into the magnetorheological fluid tank to be fixed perpendicularly at the center of the rotational inertia wheel. The control effect of the present invention may not be greatly affected by the change of a structural form and the change of an external load.

In recent years, highways, railways, bridges, high-rise buildings, large-span space structures, etc. have been continuously built, and structures such as offshore platforms, space stations and the like have also been developed rapidly. These construction facilities and structures may always vibrate under the action of an external load during use, swing under a serious condition and may even be damaged. In order to solve various problems caused by the structural vibration, a vibration control technology emerges at the right moment.
The vibration control technology is mainly classified into the following four aspects: active control, passive control, semi-active control and hybrid control. For various structures, properly mounting a vibration control system can effectively reduce the dynamic response of the structures, thereby alleviating the damage or fatigue damage of the structure caused by the vibration.
The motion of the structure is generally a combination of translational motion and torsional swing. Studies have shown that translationally tuned mass dampers (TMD), active mass dampers/active torque output devices (AMD) need to provide a centrifugal force during the torsional swing, thereby greatly weakening the control effect and even completely losing the function, and consequently being almost useless to control the torsional swing. However, the structural motion form with the torsional swinging motion characteristic is very common, such as the swing of a suspension structure (hooks, cranes, etc.), torsional swing of irregular buildings under the action of wind load, torsional swing of the offshore platform under the coupled effect of ocean waves, wind, ice, etc., torsional swinging motion of spacecrafts and space structures caused by the pose adjustment and the opening of a solar panel in the running process, and the torsional swinging motion of a vehicle body of high-speed railway locomotives caused by small excitation. Therefore, a special control system is needed to automatically overcome (or get rid of) the influence of a gravity field (centrifugal force effect) on the control system, or the working/motion rule of the control system is decoupled from the gravity field, so that the natural vibration of the system is not affected by the gravity, thereby effectively playing the control role of the control system.
Generally speaking, the existing vibration control technology mainly has the following defects: first, the translational motion TMD control device can only control the translational motion of the structure and is useless to control the torsional swing; second, the translational AMD control device can control the torsional swing, but is extremely low in control efficiency, and cannot meet the use requirement; third, a passive rotational inertia tuned damper is effective to control the torsional swinging motion, but needs to perform the complicated frequency modulation for the structure, and is low in control efficiency for some complicated structures, poor in effect, low in robustness, low in controllability, small in application range, etc.; fourth, the active invariable damping rotational control system is small in application range, and is limited in output control power and limited in control effect; and fifth, the active invariable damping rotational control system cannot guarantee the energy utilization rate and cannot meet the need for economy.
The present invention is proposed under this background.

Active composite variable damping rotational control device


A zoom lens system is disclosed, in which the decrease of the peripheral light quantity at the wide-angle end is improved. The zoom lens system comprises, in order from an object side to an image side, a first lens unit having a positive optical power, a second lens unit having a negative optical power, an aperture stop, a third lens unit having a positive optical power and a fourth lens unit having a positive optical power. The four lens units and the aperture stop are moved during zooming. When MS represents movement amount of the aperture stop during zooming from the wide-angle end to the telephoto end and M3 represents the maximum movement amount of the third lens unit in the optical axis direction during zooming from the wide-angle end to the telephoto end, −1.8<MS/M3<−0.5 is satisfied.

1. Field of the Invention
The present invention relates to a zoom lens system suitable for, for instance, image-taking apparatuses such as video cameras, digital still cameras and silver halide cameras.
2. Description of the Related Art
Recently, remarkable advancement of the miniaturization of zoom lenses for image-taking, which is associated with the miniaturization and weight reduction of home video cameras, etc., is seen, and especially, shortening the total length of the lens system, miniaturizing the front lens diameter and simplifying the lens composition are attempted.
As one of means to achieve these purposes, a so-called rear focus type zoom lens is known, in which a lens unit other than the first lens unit on the object side is moved for focusing.
Generally, in the rear focus type zoom lens, an effective diameter of the first lens unit is small as compared with a zoom lens in which the first lens unit is moved for focusing, and it is easy to miniaturize the entire system of the rear focus type zoom lens. Moreover, close image-taking, especially, very close image-taking becomes easy. In addition, there are features such as a possibility of rapid focusing, etc. since the driving power of the lens unit can be small by the miniaturization and weight reduction of the lens unit.
Conventional zoom lenses of the rear focus type have four lens units comprising, in order from the object side to the image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power and a fourth lens unit having a positive refractive power. In the zoom lenses, the second lens unit is moved for varying the magnification, and the fourth lens unit is moved for compensating the image plane fluctuation associated with the variation of magnification and for focusing (see Patent Documents 1 and 2 described below).
Moreover, zoom lenses are known, which have four lens units comprising, in order from the object side to the image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power and a fourth lens unit having a positive refractive power, wherein the second, third and fourth lens units are moved for zooming (see Patent Document 3 described below).
Moreover, zoom lenses are known, which have four lens units comprising, in order from the object side to the image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power and a fourth lens unit having a positive refractive power, wherein the first, second, third and fourth lens units are moved for zooming (see Patent Document 4 described below).
Furthermore, zoom lenses are known, which have four lens units comprising, in order from the object side to the image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power and a fourth lens unit having a positive refractive power, wherein the first, second, third and fourth lens units are moved for zooming, and the miniaturization of the total length of the zoom lens and the reduction of the front lens diameter are attempted by independently moving the aperture stop (see Patent Document 5 described below).
[Patent Document 1]
Japanese Laid-Open Patent Application No. H07-270684 (corresponding to U.S. Pat. No. 5,963,378)
[Patent Document 2]
Japanese Laid-Open Patent Application No. H11-305124 (corresponding to U.S. Pat. No. 6,166,864)
[Patent Document 3]
Japanese Patent No. 2879463 (corresponding to U.S. Pat. No. 5,179,472)
[Patent Document 4]
Japanese Laid-Open Patent Application No. 2001-194586 (corresponding to U.S. Pat. No. 6,456,441)
[Patent Document 5]
Japanese Patent No. 3352240
In the zoom lens disclosed by Patent Document 3, it is difficult to miniaturize the front lens diameter since the movement track of the third lens unit for zooming is a track convex towards the image side.
Moreover, in the zoom lens disclosed by Patent Document 4, it is difficult to obtain a high zoom ratio since the first lens unit is a single lens, and the refractive power of the first and second lenses are not so large.
Moreover, in the zoom lens disclosed by Patent Document 5, it is difficult to miniaturize the front lens diameter since the movement tracks of lens units for zooming are not necessarily the best.
In general, in a case where the sufficient light quantity in the peripheral area of the image plane is secured in four-unit-zoom lenses constituted by a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, a fourth lens unit having a positive refractive power and a stop arranged near the third lens unit, there is little decrease in the peripheral light quantity in an area up to about the 80 percent height position of the peripheral area in the image plane, but there is a steep decrease in the peripheral light quantity in an outer area (peripheral portion) from about the 80 percent height position in the image plane. Therefore, there is a problem that the decrease of the peripheral light quantity stands out.


A battery holder for containing an electric storage battery is transported by a lift unit on a mobile vehicle. The lift unit is pivotally mounted at a rearward end portion of the vehicle to move into surrounding relation with the battery holder positioned on the ground. The lift unit is pivoted upwardly to raise the battery holder to a preselected elevation within the minimal lateral and overhead clearance available in an underground mine. The lift unit includes a pair of lifting forks extending in spaced parallel relation from the vehicle within the lateral dimensions of the vehicle. The lifting forks have a configuration adapted to permit downward movement of the forks into engagement with the ground to pick up a battery holder positioned on the ground. The lifting forks extend laterally of the battery holder and engage the holder for vertical movement to an elevated position that does not exceed the uppermost position for transportation of the battery in areas of minimal overhead clearance. Piston cylinder assemblies are operable to raise and lower the lifting forks in a manner that assures secure positioning of the battery holder on the lifting forks once the lifting forks engage the holder and raise the holder to an operating height that does not exceed the maximum vertical dimension of the mobile vehicle.

1. Field of the Invention
This invention relates to method and apparatus for moving a battery into and out of position on a mobile machine and more particularly to method and apparatus for lifting a battery holder or box containing an electrical battery from an initial position on the ground to an elevated position on a machine for transporting the battery for use in powering electrical vehicles and equipment in an underground mine.
2. Description of the Prior Art
In underground mining operations it is conventional practice to supply electrically driven vehicles and electrically operated equipment with electrical power supplied from storage batteries. The batteries in some instances may be stationarily positioned at a fixed power station or mounted on mobile equipment for providing electrical power to the vehicle that transports the battery. After a period of use a spent battery must be replaced on the vehicle or at the power station with a charged battery. This requires that the spent battery and the charged battery be moved into and out of position at the place of operation.
Battery changers and exchanging devices are well known for use in transporting a battery from one location to another in a mine. An example of a vehicle battery changer is disclosed in U.S. Pat. No. 3,799,063 and includes a mobile vehicle having a low profile adaptable for use in low overhead subterranean locations, such as mine shafts. The vehicle is propelled by electric motors that are powered by electric storage batteries containing a substantial number of cells and are a substantial size and weight. The batteries are positioned in cases or boxes which are supported in compartments built into the frame of the vehicle. The batteries contained in the cases are electrically connected to the vehicle drive and control mechanisms. Lift arms are pivotally mounted to the vehicle frame and releasably attached at their free ends to the battery case. The lift arms are pivotal laterally and outwardly from the upright walls of the vehicle. The batteries on the vehicle must be replaced when the electrical charge falls below the minimum required to supply the necessary power to the vehicle. The ends of the lift arms are connected to the battery cases and the piston cylinder assemblies extending between the vehicle frame and the pivot arms are actuated to pivot the arms outwardly from the upright walls to lift the battery cases out of the compartments and lower the batteries onto the ground where the lift arms are disengaged. The spent batteries are then replaced with charged batteries which are connected to the lift arms. The lift arms are raised by the piston cylinder assemblies from the outboard position to the inboard position and then lowered into place in the battery compartment.
Where the lift arms are required to pivot laterally and outwardly from the upright walls of the vehicle, ample space must be provided between the vehicle and the side walls of the mine shaft for the batteries to be raised and lowered into and out of position in the battery compartment. In addition, substantial overhead clearance must be available to permit the battery to be raised to an elevation above the vehicle for lowering the battery into position in the battery compartment.
U.S. Pat. No. 4,397,365 discloses a front end loader powered by an electrical traction motor system. The electrical power is supplied from a storage battery that is carried by a lifting frame swingably connected to the chassis frame of the vehicle. After a period of time of operation of the front end loader, a spent battery must be exchanged for a charged battery. During the battery exchange operation the power is switched over to a low tension voltage battery on the vehicle. The high voltage battery is then disconnected from the electrically operated equipment on the vehicle. The vehicle is moved into position adjacent a pallet for receiving the spent battery. The pallet is positioned on the ground. To position the spent battery on the pallet, the lifting frame is elevated and guided into openings on the pallet to receive the battery box. The lifting frame is lowered to in turn lower the battery box on the pallet. The lifting frame passes through the openings in the pallet so that the battery box is transferred from the lifting frame to the pallet. The vehicle is then moved to another location where a charged battery is positioned on a pallet. The lifting frame is moved into a position to engage the charged battery on the second pallet. The vehicle is then backed away from the second pallet to transfer the charged battery from the pallet to the lifting frame. Thereafter, the battery is elevated by the lifting frame to complete the electrical connection of the charged battery to the operating equipment on the vehicle. The low voltage battery is then disconnected. This operation requires a substantial amount of space for maneuvering a spent battery into position on a pallet and then moving the vehicle to another pallet to pick up a charged battery, followed by transfer of the charged battery onto the vehicle. The lifting frame must be elevated above the vehicle frame in order to complete the connection of the replacement battery to the operating equipment. Therefore, substantial overhead clearance is required to change a battery.
U.S. Pat. No. 3,834,563 discloses a battery carrier by which a battery is raised from a position on the ground a minimum vertical amount and then by pivotal movement of arm assemblies is moved in a substantially greater transverse motion into a battery compartment of an electrically powered mine car. The arm assemblies are actuated by hydraulic piston cylinder assemblies to move the battery from an initial position removed from the vehicle, such as on the ground, upwardly to a vertical height a sufficient distance to clear a threshold bar of the battery compartment. The pivot arm assemblies are then moved to transfer the battery in an arcuate path into the battery compartment. Initially the battery is positioned laterally of the side wall of the vehicle so that in a confined space, such as a mine shaft, sufficient space must be available between the side wall of the mine shaft and the side wall of the battery compartment to allow for the upward and laterally swinging movement of the pivot arms. A spent battery is removed from the vehicle through the same range of movement.
U.S. Pat. No. 3,782,750 discloses a battery truck containing a box in which a large storage battery is positioned. The box completely surrounds the battery. The floor and side walls of the box are supported by a carriage that is movable by action of lever and eccentric cams to raise and lower the battery box on the truck frame. When in use, the battery is positioned in the box which rests on a fixed surface, such as the surface of a battery compartment on a vehicle where the battery is used. Once the battery is spent and is to be replaced with a charged battery, the carriage is lowered so that the battery box is raised above the supporting surface to permit the truck to be moved. When the truck is in the desired location, the battery box is then immobilized as the carriage is raised to lower the bottom of the box onto a supporting surface.
It is also known to exchange spent batteries on electrically powered equipment by moving a battery transport mechanism into position adjacent the spent battery on a vehicle. The support structure is moved laterally into underlying engagement with the spent battery to lift the spent battery from the electrically powered vehicle and transfer the battery to the adjacently positioned transport mechanism. An example of a battery handling device of this type is disclosed in U.S. Pat. No. 4,808,058.
U.S. Pat. No. 3,327,875 also discloses apparatus movable into position adjacent an electrically powered vehicle for transferring a battery from the vehicle to an adjacent carriage. This permits the battery to be removed from the vehicle and a replacement battery installed.
U.S. Pat. Nos. 4,299,526 and 4,342,533 are further examples of battery changing apparatus that include transfer mechanisms for lifting vertically and horizontally batteries into and out of position on the support surface of an electrically powered vehicle. Each of these devices require substantial clearance around the battery and the electrically operated equipment to facilitate the movement of the battery transfer device into and out of position to exchange batteries on the vehicle. These devices are not suitable for use in confined spaces, such as mine shafts, where minimal area is available for maneuvering of the electrically powered vehicle or the mechanism for transferring the batteries on the vehicle.
Therefore, there is need to provide battery changing apparatus that is suitable for use in an underground mine where limited lateral and overhead clearance is available for movement of a battery box or battery holder into and out of position on a vehicle that transports the battery throughout the mine. While the prior art devices disclose various mechanisms for handling batteries on a vehicle and particularly an electrically powered vehicle used in underground mining, there is need for battery changing apparatus that is operable to pick up a battery from the ground and move it to a secure operating position that does not require lateral or vertical movement of the lifting apparatus beyond the operating position. The range of movement of the battery changer must allow exchange of batteries on a vehicle in areas having low overhead clearance. Where the side walls of the vehicle are positioned closely adjacent to the side walls of a mine shaft the battery change must be accomplished without requiring lateral movement of the battery.


When displaying an image with at least four primary colors mixed, there are provided a primary color B generating unit (1036) having, as an xy chromaticity, (x, y)=(0.150, 0.060) and generating a primary color B lowest in luminance, a primary color G generating unit (1038) having, as an xy chromaticity, (x, y)=(0.300, 0.600) and generating a primary color G highest in luminance, and a primary color R generating unit (1037) having, as an xy chromaticity, (x, y)=(0.640, 0.330) and generating a primary color R higher in luminance than the primary color B and lower in luminance than the primary color G, whereby it is possible to expand a color gamut while ensuring compatibility with 3-primary-color image signal by allowing three primary colors to agree with the primary color Rec. 709 of a standard display sRGB.

Cross-media systems, in which a variety of image apparatuses are connected to an open system, are becoming very popular in response to advances in digital image apparatuses and network technology centering on the Internet. In open systems, image apparatuses and applications need to have a common interface and establish a configuration with high versatility and extendibility. From the aspect of color reproduction, an image apparatus sending color information, i.e., a camera or scanner, needs to send accurate color information captured to the open system. On the other hand, an image apparatus receiving and displaying color information, i.e., a display or printer, needs to display accurately the color information received. For example, even though the camera captures accurate color information, the color reproducibility of the entire system is degraded if the display can only display color information inappropriately.
To solve the above point, the IEC (International Electro-technical Commission) has established a standard, sRGB, for standard displays. This standard clearly defines the relation between RGB video signals and colorimetric values by matching the chromaticity point of the three RGB primary colors to the colorimetric parameter defined in Rec. 709 as recommended by ITU-R (International Telecommunication Union Radio Communication). Accordingly, displays complying with this standard-display standard can calorimetrically display the same colors if the same RGB video signals are given. On the other hand, displays are often used for video editing as well as viewing the images displayed. For example, displays are used for creating originals for catalog prints. Therefore, "sRGB display," the standard display, which allows colorimetrical control, is a key to color management including hard copying such as printing.
However, the above conventional image display device has the following disadvantages. "Pointer color gamut" and "SOCS color gamut" are databases that contain the color distribution of typical reflective objects in the natural world. These databases give a dynamic range of colorimetric value input to cameras, and also provide design references for the color gamut of displays. In other words, the color gamut covering at least the sum of "Pointer color gamut" and "SOCS color gamut" [hereafter (Pointer+SOCS) gamut] is required for accurately displaying the colors of naturally reflective objects.
FIG. 3A is a sectional view of a gamut solid in the CIELAB space and shows the relation between the color gamut of the sRGB display and the (Pointer+SOCS) color gamut, which is the database for color distribution of naturally reflective objects, on the plane a*-b* at equal luminance L*=50. It is apparent from FIG. 3 that color gamut 2001 of the sRGB display is smaller than color gamut 2002 of (Pointer+SOCS), indicating that the sRGB display cannot display certain naturally reflective objects. Calculation of gamut volume in the CIELAB space reveals that the sRGB display covers about 76% of the (Pointer+SOCS) color gamut, and thus 24% of the (Pointer+SOCS) color gamut is not displayable on the sRGB display. Accordingly, even though the camera captures a precise image securing a wide dynamic range covering the color distribution of a naturally reflective object, about 24% of the precisely captured image is not displayable on the sRGB display.
A conventional image device solving this disadvantage is disclosed, for example, in the Japanese Patent Laid-open Application No. 2001-306023. FIG. 10 shows the conventional image display device disclosed in this laid-open patent.
In FIG. 10, the image display device configures multiple pixels 36 aligned in a matrix. These pixels consists of sub-pixel 36R for red light, sub-pixel 36G for green light, sub-pixel 36B for blue light, and sub-pixel 36C emitting light of cyan, magenta, or yellow. This sub-pixel 36C is specified as a point on the chromaticity diagram outside of a triangular region formed by linking points of red (R), green (G), and blue (B) on the chromaticity diagram shown in FIG. 11. The CMY in FIG. 11 indicates cyan (C), magenta (M), and yellow (Y).
In the above conventional configuration, however, a color display range changes with luminance because no restriction on luminance is provided. This makes it difficult to secure compatibility with the sRGB display when the fourth primary color is added.
More specifically, the shape and size of the color gamut of the display are determined by the positions of the primary color points. Since the color space is three-dimensional, primary color points have three-dimensional coordinates. In the case of the sRGB display, each primary color R (primary color red), primary color G (primary color green), and primary color B (primary color blue) possesses two-dimensional chromaticity coordinates (x, y) and one-dimensional luminance Y The (Pointer+SOCS) color gamut is also a three-dimensional solid. In order to display the precise colors of naturally reflective objects, two-dimensional chromaticity coordinates and one-dimensional luminance of primary colors of the display need to be determined such that the color gamut solid of the display covers the (Pointer+SOCS) color gamut solid to the maximum extent possible.

Image displaying method and image displaying device

Matsushita Electric Industrial Co., Ltd.


Method of and system for analysing a set of exhaustive and exclusive hypotheses, including assessing and assigning base rates for each hypothesis; determining a set of items of evidence that are relevant to, have a causal influence on, or would disconfirm more than one hypothesis; assessing and assigning base rates for each item of evidence; deciding, for each item of evidence, whether the item should be treated as being a causal influence or diagnostic indicator with respect to the set of the hypotheses; if the item of evidence is to be treated as a causal influence—making a judgement as to the likelihood of each hypothesis, both if the evidence were true, and also if the evidence were false; if the item of evidence is to be treated as a diagnostic indicator—making a judgement as to the evidence being true if the hypothesis were true; assessing the belief for each item of evidence being true; deciding a set of interim beliefs in each hypothesis for each individual item of evidence by:                employing a conditional inference operator for evidence that is to be treated as a causal influence; and        employing a reverse conditional inference operator for evidence that is to be treated as a diagnostic indicator; anddeciding the overall belief in each hypothesis by employing a consensus operator on the respective set of interim beliefs.

1. Field of the Invention
The present invention relates to a method for analysis of competing hypotheses. In particular, although not exclusively, the invention provides a method for the analysis of intelligence, wherein intelligence deals with all the things which should be known in advance of initiating a course of action.
2. Discussion of the Background Art
Intelligence analysis is a complicated task that requires a high degree of analytical judgement under conditions of considerable uncertainty. This judgement is used to fill in the gaps in knowledge and is the analyst's principal means of managing uncertainty. Much of intelligence analysis includes judging the relevance and the value of evidence to determine the likelihood of competing hypotheses.
Intelligence is a difficult term to define precisely, yet its role and importance can be both intuitively understood and appreciated. From one perspective it may be seen as an end product, i.e. 'information' that is used to enhance or aid a decision making process. From another perspective, it may refer to the process that is applied to information, in order to transform it into a more useful product. More importantly than what intelligence is perhaps, is what intelligence does. Intelligence, both as a product and a process, is a means by which better decisions can be made, based on an increased understanding of likely courses of action, their influences and their consequences.
In everyday personal affairs few of our decisions use any directed analytical processes, and even fewer of these require any sort of rigorous approach. Arguably this is due to relatively minor consequences of the decisions we face in such everyday affairs. The same is not true for large-scale human affairs, such as the business of nations and corporations, where the complexity of the environment and the relative consequences of decisions can have enormous impact on the well-being and survival of a nation's citizenry or a corporation's ability to compete. This distinction in and of itself is cause enough to consider whether human 'everyday reasoning' is robust and reliable enough for use in these larger contexts.
As it happens, humans typically systematically make substantive errors in reasoning due to problems of framing, resistance of mental models to change, risk aversion, limitations of short-term memory, and other cognitive and perceptual biases. This has severe implications for the process of intelligence analysis, and may lead to incorrect conclusions, especially in situations that appear familiar but which actually result in different outcomes; in situations where the gradual assimilation of information into established mental models results in the failure to detect 'weak signals' that should have triggered a major re-evaluation; and in situations where the complexity of the mental models are untenable due to human limitations of short-term memory.
When applied to the business of nation states, the consequences of intelligence failure can be disastrous, so much so that the recorded history of the world, both ancient and modern, is replete with a litany of devastating intelligence failures too numerous to list. Examples of these failure are easily found in any period of history, such as the failure of the United States during World War 2 to perceive an impending attack on Pearl Harbour and the failure of Japan to reason that Midway Island was a trap, with the consequent sinking of four Japanese aircraft carriers and the loss of all crews, aircrews and aircraft. It is therefore foolhardy to believe that good intelligence can be developed by relying solely on human cognition without resort to products, methodologies or frameworks that attempt to augment human cognition while also mitigating its defects.
Intelligence analysis generally requires that analysts choose from among several alternative hypotheses in order to present the most plausible of these as likely explanations or outcomes for the evidence being analyzed. Analysts that do not use some form of rigorous methodology will often work intuitively to identify what they believe to be the most likely explanation and then work backwards, using a satisficing approach where the 'correct' explanation is the first one that is consistent with the evidence. The major downfall of the satisficing approach is that there may be more than one explanation that is consistent with the evidence, and unless the analyst evaluates every reasonable alternative, they may arrive at an incorrect conclusion.
Other common problems with using this strategy include the failure to generate appropriate alternative hypotheses; the propensity to filter and interpret the evidence to support the conclusions; and the failure to consider the diagnosticity of the evidence and how well it differentiates between hypotheses. The recognition of these problems with their disastrous consequences has led to the development of Alternative Analysis techniques that are widely employed, for example, within the intelligence services, see R. J. Heuer, Psychology of Intelligence Analysis. Washington, D.C.: Central Intelligence Agency Center for the Study of Intelligence, 1999. [Online] Available: http://www.cia.gov/csi/books/19104.
Other strategies that are less commonly used in intelligence analysis and are also ineffective are discussed in detail by George, A.; Presidential Decisionmaking in Foreign Policy: The Effective Use of Information and Advice. Boulder Colo., USA: Westview Press, 1980. Many alternative analysis techniques attempt to address the problems of fixed mind-sets and incomplete generation of alternative hypotheses, while still others attempt to address the problems of reasoning about the alternative hypotheses, such as R. Z. George, Fixing the problem of analytical mind-sets: Alternative analysis, International Journal of Intelligence and Counter Intelligence, vol. 17, no. 3, pp. 385-405, Fall 2004.
One way in which some of the problems of reasoning about alternative hypotheses could be addressed is to require the analyst to simultaneously evaluate all reasonable hypotheses and reach conclusions about their relative likelihood, based on the evidence provided. However, simultaneous evaluation of all non-trivial problems is a near-impossible feat for human cognition alone. Recent research suggests the number of individual variables we can mentally handle while trying to solve a problem is relatively small, four (4) variables are difficult, while five (5) are nearly impossible according to G. S. Halford, R. Baker, J. E. McCredden, and J. D. Bain, How many variables can humans process? Psychological Science, vol. 16, no. 1, pp. 70-76, January 2005. The Analysis of Competing Hypotheses (ACH) Heuer op cit was developed to provide a framework for assisted reasoning that would help overcome these limitations.
Heuer's Analysis of Competing Hypotheses (ACH)
The ACH methodology was developed in the mid- to late-1970's by Richard Heuer, a former CIA Directorate of Intelligence methodology specialist, in response to his never-ending quest for better analysis. The ACH methodology is still considered to be highly relevant today, see F. J. Stech and C. Elässer, Midway revisited: Deception by analysis of competing hypothesis, MITRE Corporation, Tech. Rep., 2004. [Online] Available: http://www.mitre.org/work/tech papers/tech papers 04/stech deception. ACH typically consists of the following eight steps:                1) Identify the possible hypotheses to be considered, for example use a group of analysts with different perspectives to brainstorm the possibilities.        2) Make a list of significant evidence and arguments for and against each hypothesis.        3) Prepare a matrix with hypotheses across the top and evidence down the side. Analyze the "diagnosticity" of the evidence and arguments—that is, identify which items are most helpful in judging the relative likelihood of the hypotheses.        4) Refine the matrix. Reconsider the hypotheses and delete evidence and arguments that have no diagnostic value.        5) Draw tentative conclusions about the relative likelihood of each hypothesis. Proceed by trying to disprove the hypotheses rather than prove them.        6) Analyze how sensitive your conclusion is to a few critical items of evidence. Consider the consequences for your analysis if that evidence were wrong, misleading, or subject to a different interpretation.        7) Report conclusions. Discuss the relative likelihood of all the hypotheses, not just the most likely one.        8) Identify milestones for future observation that may indicate events are taking a different course than expected.These eight steps are intended to provide a basic framework for identification of assumptions, arguments and hypotheses; consideration of all evidence and hypotheses, including its value relative to the hypotheses; a method of disconfirmation for identifying the most likely hypotheses; an approach to reporting the results of the analysis; and an approach to detecting future changes in the outcomes.
In simple terms, ACH requires the analyst to simultaneously evaluate all reasonable hypotheses and reach conclusions about their relative likelihood, based on the evidence provided. Heuer acknowledges that while this holistic approach will not always yield the right answer, it does provide some protection against cognitive biases and limitations. Of particular interest is step 5, which requires the analyst to draw tentative conclusions about the likelihood of each hypothesis. It has been argued that ACH recommends analysts consider the likelihood of each hypothesis h given the assertion of each item of evidence, e, i.e. p(h|e). However, this can reasonably be interpreted to mean that the negation of each item of evidence, not e should also be considered (p(h|not e)). Consideration of counterfactuals has the advantage that the model can be constructed independently of known facts and continually evaluated if the value of the evidence changes over time.
The difference in interpretation lies in whether the evidence with respect to the hypotheses is considered a priori or a posteori. Evidence can be constructed a posteori by the analyst from the 'facts at hand', where the evidence has already been measured and valued, rather than from a general examination of the possible signs for each hypothesis. While examination of available data is usually relevant, 'hidden facts', i.e. conditions which are not observable, or conditions which have not yet taken place, are also likely to be relevant to the analysis. If reasoning is conducted a priori, then the value of the evidence is uncertain, and the analyst is more likely to consider the consequences of it being false as well as the consequences of it being true. If the reasoning is a posteori, the analyst may know whether the evidence is true or false, and not consider its counterfactual to be relevant in determining the likelihood of the hypothesis. This is a mistake, since the analysis model will no longer be relevant if the value of the evidence changes, or there is uncertainty about its value.
Richard Heuer points out that analysts should interpret 'evidence' in its broadest sense and not limit oneself just to current intelligence reporting. Indeed ACH is able to model the absence of evidence as well as its presence, and when done diligently presents no conceptual problem. However, ACH does not require analysts to consider both the assertion and negation of evidence, and this deficiency may lead them to frame the problem in terms of a single view of evidence, which often leads to incorrect conclusions, especially if deception or denial is being undertaken by an adversary.
Analysis of Competing Hypotheses—Counter Deception (ACH-CD)
ACH-CD was developed by Frank Stech and Christopher Elässer of the MITRE Corporation as a modified variant of ACH to account for cognitive factors that make people poor at detecting deception: Stech & Elässer op cit. The authors correctly argue that the use of ACH can lead to greater susceptibility for deception, especially when reasoning about a single view of evidence, i.e. the likelihood of each hypothesis given the assertion of the evidence p(h|e). Their argument is that this type of reasoning neglects the base rates both of the evidence br(e) and of the hypothesis br(h) which can result in reasoning errors that lead to incorrect conclusions, see K. Burns, Mental Models and Normal Errors. Lawrence Erlbaum Associates, 2004, ch. How Professionals Make Decisions. [Online] Available: http://mentalmodels.mitre.org/Contents/NDM5_Chapter.pdf. More correctly it should be said that reasoning using only one of the logical conditionals (usually the positive conditional, p(h|e)) is more likely to produce reasoning flaws than when both are considered. Stech and Elässer make the same point when they argue that analysts' judgements are more susceptible to deception if they also do not take the false positive rate of the evidence into account. An example of this susceptibility to deception is provided by Stech and Elässer is how the reasoning about the detection of Krypton gas in a middle-eastern country can lead to the erroneous conclusion that the country in question likely has a nuclear enrichment program. For clarity, their example has been reproduced below:Detect Kryptonp(enrichment|Krypton)=high→p(enrichment program)=high→p(nuclear program)=highThey argue that the main problem with this reasoning is that it does not consider that Krypton gas is also used to test pipelines for leaks, and that being a middle-eastern country with oil pipelines, the probability of the gas being used outside of a nuclear program is also fairly high, i.e. p(Krypton|not enrichment)=medium to high. This additional information should lead the analyst to the conclusion that there is a fair amount of uncertainty of a nuclear program given the detection of Krypton. The assignment of the 'high' value to p(enrichment|Krypton) neglects the fact that an oil-rich middle-eastern country is likely to use Krypton gas, regardless of whether they have a nuclear program.
However, it can be argued that Stech and Elässer have interpreted Step 5 of ACH more narrowly than perhaps was intended. Heuer makes no claim about which of p(h|e) or p(e|h), and their corresponding counterfactuals p(h| not e), p(e| not h), should be used. Heuer describes the process in such general terms as to be consistent with either interpretation, although consideration of counterfactuals is essential if basic reasoning errors are to be avoided. In any event, it can be shown that p(h|e) and p(h|not e) can be derived from knowledge of p(e|h), p(e|not h) and the base rate of the hypothesis br(h). Therefore the choice of which logical conditionals to use is less important then the soundness of the belief values assigned to them. The choice of logical conditionals becomes more important when the analyst considers whether the evidence is causal in nature with respect to the hypotheses, or is merely derivative. The problem of framing with respect to the causal or derivative nature of evidence and the implications for reasoning is discussed further below.

Intelligence analysis method and system using subjective logic


A wheel immobilizing cover for roller blade roller skates includes an elongated channel, a non-adjustable or fixed bridle of flexible, rubberized material which is subject to arcuate movement about an effective pivot point located on the sidewalls of the channel and an adjustable bridle coupled to the base of the channel. The adjustable bridle moves arcuately about the coupling point. The fixed bridle which is detached, at its outer end, from the base captures the front wheel of the roller blade skate wheels on the upper forward quadrant of the wheel and the adjustable bridle captures the rear wheel of the roller blade skate wheels on the upper rear quadrant of the wheel. When the front wheel rotates the wheel drags the flexible fixed bridle along the flexible, fixed bridle effectively pivoting about some pivot point on the channel and because of the difference in the paths of arcuate travel between the front wheel and the fixed bridle, the front wheel is clamped and immobilized. When the rear wheel rotates the wheel drags the adjustable bridle along and because of the difference in the paths of arcuate travel between the rear wheel and the adjustable bridle, the rear wheel is clamped and immobilized.

1. Field of the Invention
The present invention relates to a cover for the wheels of a roller blade skate. In particular, the invention is a cover for the wheels of a roller blade skate for immobilizing the wheels and protecting the wheels of the skate.
2. Prior Art
Skates, both roller skates and ice skates are used in both recreational and professional sports. Skating rinks, for both ice skating and roller skating are very popular for both professional and recreational use of skates. In the recreational rink skating, the social aspects of the sport are almost as much a part of the sport as the actual skating.
All skates, whether they be roller skates or ice skates appear to have a common objection relative wearing the skate off the surface of the rink, in, for example, the social and personal rest areas and/or the refreshment area of the rink. The objections to off-the-skating-surface use of skates have foundation in safety, both of the person wearing the skate and the surface over which the person wearing the skate is walking. When a person is at a skating rink for skating purposes, the person usually takes a break between skating secessions for refreshment purposes. It is also usual for the rink-skater to attend refreshment and rest areas with the skates on his feet, since it is bothersome to remove and replace the skates, the skater usually keeps the skates on, until the skater is ready to leave the rink. It is also usual to require that persons wearing skates in the refreshment area and/or the rest area of rinks have a satisfactory cover over the roller skate wheels or the ice skate blade.
In the case of roller skates, there are, at present, two popular type of roller skates. One popular type is the conventional roller skate which has two longitudinally spaced pairs of wheels on one skate. This type of skate is hereinafter referred to as a conventional roller skate. Another popular roller skate is a multi-wheel skate in which the wheels of each skate are mounted in a single line, in tandem alignment. This type of roller skate is referred to hereinafter as a roller blade skate. A currently popular roller blade skate has four (4) wheels mounted on each skate of a pair of skates. The four (4) wheels of the wheel assembly on each skate, are mounted in a single, straight line, so as to be aligned, in tandem.
A cover for the wheels of a roller skate is taught by Grim in his U.S. Pat. No. 4,355,474, which addresses the problem of covering the wheels of a conventional roller skate. Grim teaches a sheet type cover which hooks on to the end structure of the skate mounting, covering the spaced pairs of wheels with a flat, rectangular sheet. The sheet cover provides a surface or sole on which a skater may walk, with some safety, when not on the skating rink.
The roller skate sole of the '474 patent is not practical for use on a roller blade skate because of the wheel alignment of the skate. Further, the Grim teaching addresses the problem of covering wheels on conventional roller skates, taking account that the conventional roller skate has a wheel arrangement that provides a rectangular, almost square, area with which to work. This same type of rectangular area is not found on, nor defined by the wheels mounted on a roller blade skate.
Ice skate guards, such as taught in U.S. Pat. Nos. 1,174,601 to Nathan; 1,686,667 to Kaskey; and, 3,583,720 to Fowlkes address the problem of protecting the blades of ice skates and do not address the problem of immobilizing the the wheels on wheel equipped skates, such as on the roller blade skate. The guards taught in the prior art for protecting the blades on ice skates are not designed for use on roller blade skates and fail to immobilize the tandem aligned wheels of the roller blade skates.


Semiconductor bipolar power devices comprise a control electrode for turning on or off a first source of charge carriers into the device and a p-n junction emitter remote from the first source and acting in correspondence with the condition of the first source. The p-n junction is a heterojunction where the bandgap of the semiconductor material of the emitter side of the junction is less wide than the bandgap of the material on the base side for reducing the emitter injection efficiency in comparison with an otherwise identical device having a homojunction emitter.

This invention relates to semiconductor devices in general, and particularly to bipolar semiconductor devices of the type used for controlling the flow of electrical power.
In the design of bipolar semiconductor power devices, there is generally a trade-off between low on-state voltage drop across the device and fast switching time, particularly fast turn-off of the device. Low voltage drop is achieved by bipolar operation, i.e., the introduction of both p and n type charge carriers through the device for obtaining large charge carrier densities. Large densities cause the device to operate in a "conductivity modulated" mode providing a low resistance to current flow. Conversely, because switching off the device requires removal of charge carriers from within the device, large current densities tend to increase device turn-off time.
The trade-off generally accepted is the use of bipolar operation for high charge carrier density, but operation at a level of charge density somewhat reduced from the maximum density otherwise available. Typically, for example, two "areas" of origination of charge carriers are present in each device, a first of which is under the "direct" control of a nearby control electrode, and the second of which is spaced from the first "area" and which operates in response to the turn-on and turn-off of the first area. (As described hereinafter, the term "area of origination" is intended to cover both "source regions" in field-effect devices and "emitter regions" in high-low and p-n junction devices.)
In all devices in which the present invention has utility, the second "area" is a p-n junction across which charges are injected by an "emitter". Typical techniques for reducing the amount of charge injected across a p-n junction include reducing the effective size of the junction, e.g., by providing charge carrier paths ("shorts") bypassing the p-n junction, and/or selective doping of the emitter region and/or the adjoining region forming the p-n junction with the emitter region. The shorted emitter construction tends to be complex and relatively expensive and the selective doping, depending upon the doping scheme used, can also add complexity and cost to the device or be otherwise undesirable in terms of device performance or manufacture.
Another technique for improving device turn-off speed is to reduce the life-time of the charge carriers within the device, e.g., by the introduction of carrier recombination sites. However, this is undesirable for, among other things, adding extra processing and cost to the devices.
The present invention is directed to a different mechanism for obtaining reduced injection efficiency of the second "area of origination" of charge carriers within the devices, that is, the p-n junction emitter region remote from the gate controlled first "area" of the devices, which different mechanism provides certain advantages in device performance and device manufacture. The "different mechanism" hereinafter described can, depending upon the particular semiconductor device being made, be used in combination with known mechanisms, e.g., lifetime control mechanisms.

Bipolar semiconductor power controlling devices with heterojunction