A method and an apparatus for manufacturing trichlorosilane are disclosed. A polymer containing high boiling chlorosilane compounds that are generated in a polycrystalline silicon manufacturing process are mixed with hydrogen chloride and introduced into a decomposition furnace. The polymer and the hydrogen chloride are reacted at a temperature of 450° C., and preferably of 450° C. or more and 700° C. or less. Preferably a mixture containing the polymer and hydrogen chloride of 10 to 30 mass % with respect to the weight of the polymer is introduced into the decomposition furnace.

Field of the Invention
The present invention relates to a method and an apparatus for manufacturing trichlorosilane by decomposing compounds (hereinbelow, referred to as "polymers") containing high-boiling chlorosilane, which are generated in a polycrystalline silicon manufacturing process. In particular, the present invention relates to a method and an apparatus for manufacturing trichlorosilane by decomposing polymers that have been separated in a chlorination step or polymers that have been separated from an exhaust gas of a polycrystalline silicon manufacturing process.
Priority is claimed on Japanese Patent Application No. 2008-049229, filed Feb. 29, 2008, the content of which is incorporated herein by reference.
Description of Related Art
The high-purity polycrystalline silicon that can be used as a semiconductor material is mainly manufactured by the Siemens process in which, for example, trichlorosilane (SiHCl3; abbreviated "TCS") and hydrogen are used as raw materials, a gas mixture thereof is introduced into a reactor and brought into contact with heated silicon rods, and silicon is deposited on the surfaces of the silicon rods due to the hydrogen reduction or thermal decomposition of the trichlorosilane at a high temperature.
The high purity trichlorosilane to be introduced into the reactor, for example, is manufactured by introducing metallurgical grade silicon and hydrogen chloride into a fluidized-bed chlorination furnace to react them, chlorinating the silicon to produce crude TCS (chlorination step), and purifying the crude TCS by distillation into high purity TCS.
In the manufacture of polycrystalline silicon, the reactor exhaust gas includes, in addition to unreacted trichlorosilane, hydrogen, and hydrogen chloride, by-products such as silicon tetrachloride (STC) and chlorosilanes including, for example, tetrachlorodisilane (Si2H2Cl4) and hexachlorodisilane (Si2Cl6). (Patent Document 1: PCT International Publication WO 02/012122) The chlorosilanes have boiling point higher than that of silicon tetrachloride, and they are referred to herein as "high boiling chlorosilanes". Also, the gas produced in the chlorination reactor includes, in addition to trichlorosilane and unreacted hydrogen chloride, by-products such as silicon tetrachloride and high-boiling chlorosilanes.
Conventionally, when the gas that has been produced in the chlorination reactor is purified by distillation, separated polymers undergo a hydrolytic process and are then discarded. The exhaust gas of the reactor is introduced into a recovery distillation column, and after the polymers have been separated, the exhaust gas is returned to the distillation step of the chlorination step and recycled. However, the separated polymers undergo a hydrolytic process and are then discarded. Thus, there is problem in that the hydrolytic and the waste disposal processes are costly.
A method is known in which the polymers generated in the manufacture of polycrystalline silicon are returned to the fluidized-bed chlorination furnace and then decomposed and used in the manufacture of trichlorosilane (Patent Document 2: Japanese Unexamined Patent Application, First Publication No. H01-188414). However, in this method, because the silicon powder and polymers supplied to the chlorination reactor are mixed, there is a problem that the fluidity of the silicon powder is reduced and the conversion rate of the silicon powder to chlorosilanes is lowered.

Method and apparatus for manufacturing trichlorosilane


Even when an input is small in a current supply capacity, a differential amplifier circuit capable of outputting a high accurate voltage with an offset corrected can be obtained. In the differential amplifier having first and second input terminals and an output terminal, a control is made for switching between a first state wherein a first input terminal is taken as a non-inverting input terminal, and a second input terminal is taken as an inverting input terminal, and a second state wherein the first input terminal is taken as an inverting input terminal and the second input terminal is taken as a non-inverting input terminal, and further, a capacity element, one end of which is connected to a predetermine power source terminal, is provided, and moreover, a control is made such that the first input terminal is supplied with an input voltage, and the other end of the capacity is connected to the second input terminal and output terminal in the first state, and the first input terminal is connected to the output terminal, and the other end of the capacity is connected to the second input terminal in the second state. In this way, an offset detecting operation is performed in the first state, and an offset correcting operation is performed in the second state without the input voltage connected to the capacity.

1. Field of the Invention
The present invention relates to a differential amplifier circuit and a drive circuit of a liquid crystal display unit using the same, and more in particular, it relates to improvement of the differential amplifier circuit which is removed from an offset in order to drive a load with a high degree of accuracy.
2. Description of the Prior Art
Heretofore, there has been a problem of the differential amplifier circuit for driving a load developing an output offset because of variation in characteristics of active elements configuring the differential amplifier circuit. To solve this problem, there have been various methods employed so far to correct the output offset. From among those methods, the differential amplifier circuit as disclosed in Japanese Patent Laid-Open No. 9-244590 (patent document 1) is cited as an example of the differential amplifier circuit of a first conventional example having an output offset correcting means using a capacitance.
FIG. 19 is a view showing the differential amplifier circuit of a first conventional example having the output offset correcting means as disclosed in this patent document 1. The differential amplifier circuit of FIG. 19 comprises an operational amplifier circuit 503 and an offset correcting circuit 504. The offset correcting circuit 504 comprises switches 506 and 507 connected in series between a non-inverting input terminal of the operational amplifier circuit 503 and an output terminal 502 of the operational amplifier circuit 503, a capacitor 505 connected between a mutual connecting point of the switches 506 and 507 and an inverting input terminal of the operational amplifier circuit 503, and a switch 508 connected between the inverting input terminal of the operational amplifier circuit 503 and the output terminal 502 of the operational amplifier circuit 503.
FIG. 20 shows an operational timing chart of the differential amplifier circuit of FIG. 19. The operation of the differential amplifier circuit of FIG. 19 will be described below with reference to the timing chart of FIG. 20. First, in the period T1 which is a proceeding state, the switch 507 alone is put into an ON state, and other switches 506 and 508 are put into an OFF state. This allows the output terminal 502 and the inverting input terminal of the operational amplifier circuit 503 to be connected through the capacitor 505. In this state, the preceding output voltage carries over the voltage level of an output voltage Vout.
In the next period T2, in addition to the switch 507, the switch 508 is turned ON. When the voltage level of the input voltage Vin changes, the output voltage Vout changes accordingly, and becomes (Vin+Voff) including an output offset Voff. At this time, the capacitor 505 is short-circuited, and both ends of the capacitor 505 become the same potential. Further, by turning the switches 507 and 508 ON, the both ends of the capacitor 505 are connected to the output terminal 502 of the operational amplifier circuit, and therefore, the potentials of both ends of the capacitor 505 become Vout (=Vin+Voff) by the output of the operational amplifier circuit, respectively.
In the next period T3, while the switch 508 is turned ON as it is, the switch 507 is turned OFF, and after that, the switch 506 is turned ON. This allows one end of the capacitor 505 to be connected to an input terminal 501 and change from Vout to Vin. Since the switch 508 is turned ON, the other terminal of the capacitor 505 remains the output voltage Vout. Hence, the voltage applied to the capacitor 505 becomes as followsVout−Vin=Vin+Voff−Vin=Voffand a charge equivalent to the offset voltage Voff is charged to the capacitor 505.
In the next period T4, the switches 506 and 508 are turned OFF, and after that, the switch 507 is turned ON. By turning the switches 506 and 508 OFF, the capacitor 505 is directly connected between the inverting input terminal and the output terminal 502 of the operational amplifier circuit 503, and the output offset Voff is held by the capacitor 505. By turning the switch 507 ON, the output offset Voff is applied to the inverting input terminal of the operational amplifier circuit 503 with the potential of the output terminal 502 as a reference. As a result, the output voltage Vout becomes as followsVout=Vin+Voff−Voff=Vinand therefore, the output offset is canceled, and a highly precise voltage can be outputted.
Next, as a second conventional example for correcting the output offset, amplifier circuits as disclosed in Japanese Patent Laid-Open Nos. 11-249624 (patent document 2) and 11-305735 (patent document 3) are cited. FIG. 21 is a circuit diagram showing a basic circuit configuration of a low voltage amplifier circuit shown in the patent document 2, and FIG. 22 is a circuit diagram showing the basic circuit configuration of a high voltage amplifier circuit as similarly disclosed in the patent document 2.
The low voltage amplifier circuit shown in FIG. 21 is provided with switching transistors NA1 and NB1 which connects the gate electrode (control electrode) of a P channel (hereinafter, referred to simply as P) MOS transistor PM51 of an input stage to either a (+) input terminal or a (−) input terminal, switching transistors NA2 and NB2 which connects the gate electrode of the PMOS transistor PM52 of the input stage to the (+) input terminal or the (−) input terminal, switching transistors NA3 and NB3 which connects the gate electrode of a N channel (hereinafter, referred to simply as N) MOS transistor NM65 of an output stage to either the drain electrode (second electrode) of the PMOS transistor PM51 of the input stage or the drain electrode of the PMOS transistor PM52 of the input stage, and switching transistors NA4 and NB4 which connects the gate electrodes of the NMOS transistors NM63 and NM64 configuring an active load circuit to either the drain electrode of the PMOS transistor PM51 of the input stage or the drain electrode of the PMOS transistor PM52 of the input stage.
A high voltage amplifier circuit shown in FIG. 22, similarly to the low voltage amplifier circuit shown in FIG. 21, is provided with switching transistors PA1 to PA4 and PB1 to PB4. Here, the gate electrodes of switching transistors NA1 to NA4 and PA1 to PA4 are applied with a control signal A, and the gate electrodes of switching transistors NB1 to NB4 and PB1 to PB4 are applied with a control signal B.
In the low voltage amplifier circuit shown in FIG. 21, a circuit configuration is shown in FIG. 23 where the control signal A is at a H (high) level and the control signal B is at a L level, and a circuit configuration is shown in FIG. 24 where the control signal A is at a L (low) level and the control signal B is at an H level. As evident from these FIGS. 23 and 24, in case of the low voltage amplifier circuit, the MOS transistor of the input stage applied with the input voltage Vin and the MOS transistor of the input stage fed back with the output voltage Vout are exchangeable. Consequently, in the cases of the circuit configuration of FIG. 23 and the circuit configuration of FIG. 24, an output offset is generated in the amplifier circuit where reference numerals are in reverse to one another and the absolute values thereof are equal.
Further, in the high voltage amplifier circuit shown in FIG. 22 also, in the cases of the circuit configuration where the control signal A is at the H level and the control signal B is at the L level and the circuit configuration where the control signal A is at the L level and the control signal B is at the H level, the output offset is generated in the amplifier circuit where reference characters are in reverse to one another and the absolute values thereof are equal.
It is disclosed in the circuit configuration of the patent document 2 that, in an image signal line driving means of the liquid crystal display unit for performing a dot inversion driving, to apply a gradation voltage to a piece of pigment, a high voltage side amplifier circuit for outputting a positive polarity gradation voltage and a low voltage side amplifier circuit for outputting a negative polarity gradation voltage are alternately operated for every frame in response to the polarity, and an operation of alternately changing the MOS transistor of the input stage applied with the input voltage of the amplifier circuit and the MOS transistor of the input stage fed back with the output voltage for every two frames is performed, whereby the output offset generated for each amplifier circuit is equalized for every four frames time-wise. By so doing, the increase and decrease of brightness generated by variation of a voltage applied to the pigment by the output offset is prevented.

Differential amplifier circuit and drive circuit of liquid crystal display unit using the same


An EEPROM device includes a split-gate FET (10) having a source (36), a drain (22), a select gate (16) adjacent the drain (22), and a control gate (32) adjacent the source (36). When programming the split-gate FET (10), electrons are accelerated in a portion of a channel region (38) between the select gate (16) and the control gate (32), and then injected into a nitride layer (24) of an ONO stack (25) underlying the control gate (32). The split-gate FET (10) is erased by injecting holes from the channel region (38) into the charge nitride layer (24). When reading data from the split-gate FET (10), a reading voltage is applied to the drain (22) adjacent the select gate (16). Data is then read from the split-gate FET (10) by sensing a current flowing in a bit line coupled to the drain (22).

The present invention relates, in general, to a memory device and, more particularly, to a nonvolatile memory device.
An Electrically Erasable Programmable Read Only Memory (EEPROM) permits stored data to be retained even if power to the memory is removed. An EEPROM cell stores data either by storing electrical charge in an electrically isolated floating gate of a field effect transistor (FET) or by storing electrical charge in a dielectric layer underlying a control gate of a FET. The stored electrical charge controls the threshold of the FET, thereby controlling the memory state of the EEPROM cell.
Conventionally, an EEPROM cell is programmed using drain side hot carrier injection to inject charge carriers either onto a floating gate or into charge trapping sites in a dielectric layer underlying a control gate. High drain and gate voltages are used to speed up the programming process. Thus, the FET in the EEPROM cell conducts a high current during programming, which is undesirable in low voltage and low power applications. Further, the EEPROM cell operates very close to breakdown during programming.
Breakdown conditions during programming can be avoided by using source side carrier injection. To program an EEPROM cell using source side hot carrier injection, a select gate is formed overlying a portion of the channel region adjacent the source region. The select gate is electrically isolated from a control gate formed adjacent the drain region. During programming, an electric field is established in the channel region so that charge carriers originating in the source region are accelerated across the channel region before being injected into a floating gate or a dielectric layer located below the control gate. The select gate controls the channel current. Thus, programming with source side hot carrier injection is more power efficient than the conventional drain side hot carrier injection and suitable for low voltage and low power applications.
Accordingly, it would be advantageous to have a nonvolatile memory device and a method for accessing the nonvolatile memory device which is power efficient and suitable for low power applications. It is also desirable for the nonvolatile memory device to be simple and inexpensive to fabricate, and silicon area efficient. In addition, it is also desirable for the accessing method to be reliable and time efficient.

Split-gate memory device and method for accessing the same


The present invention relates to a wireless local area network (WLAN). In the present invention, an access point transmits and receives a probe frame including identity numbers of each access point with a near access point, determines a master access point, and establishes a connection with a near access point through a first radio channel. The master access point transmits a beacon frame, including time information, to a station through a second radio channel, and establishes a connection with the station. The master access point relays a wired internet service received from internet network to the station. Thereafter the master access point switches the connection to the first radio channel and transmits a data frame to the near access point connected with a target station.

1. Field of the Invention
Generally, the present invention relates to a wireless local area network (WLAN), more particularly to an apparatus and a method for providing a frame bridge of an access point.
2. Discussion of the Related Art
Generally, a wireless local area network (WLAN) includes radio devices functioning as mobile stations and access points functioning as connectors to the stations.
To be properly applied to a wireless medium, each element forms a WLAN through a medium access control (MAC) protocol defined in IEEE (Institute of Electrical and Electronics Engineers) 802.11 and a wireless network interface card (NIC) supporting a physical layer standard. An exemplary diagram for the above WLAN is shown in FIG. 1.
As shown in FIG. 1, a WLAN includes access points 4 and 5 and wireless stations STA 6, 7, and 8 connected with the access points. The access points 4 and 5 and the wireless stations 6, 7, and 8 construct a mutually connected structure in accordance with the MAC protocol standard and the physical layer standard defined in IEEE 802.11.
Each access point 4, and 5 relays a wired Internet service received from the Internet 1 to the wireless stations 6, 7, and 8 through a gateway 2 that is connected with a wired medium 3. Herein, the access point 4 functions as a bridge which relays a frame to a non directly connected wireless station 8 through the near access point 5 which is linked to the wired medium 3.
The access point in the WLAN of the above mentioned structure has generally the same function as a station. The access point provides the link service between the WLAN and a wired LAN so that each station may access a distribution system. Therefore the access point includes at least one wired LAN and at least one WLAN.
A frame bridge of the access point is to identify a MAC address of a is station and to transmit a frame to be relayed to the predetermined station. The access point provides the link service between a WLAN and a wired LAN by this frame bridge.
However, the frame bridge of the access point is available when at least one wired LAN is used or when a radio basic service set (BSS) is not supported.
In detail, it is difficult for an access point having one NIC (Network interface card) to operate its own wireless BSS and provide a wireless frame bridge with a near access point simultaneously through different channels.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the background of the invention, and therefore, unless explicitly described to the contrary, it should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known in this country to a person of ordinary skill in the art.

Apparatus and method for providing frame bridge of wireless local area network

Electronics and Telecommunications Research Institute


A pad conditioning apparatus and method for conditioning a surface of a polishing pad which is used in a polishing apparatus for polishing works, having a bending or deflecting or elastic member and a supporting section to support a base end of the bending or deflecting or elastic member, wherein the bending or deflecting or elastic member elastically deforms upon contact of a vicinity of a tip end of the bending or deflecting or elastic member with the polishing pad, so that a pressure necessary to condition the pad is generated. A pad preparation apparatus using the pad conditioner; and a pad preparation method using the same, enable even conditioning of a polishing pad of an elastic body by following a surface of the polishing pad.

1. Field of the Invention
The present invention relates to a pad conditioner, a pad conditioning method, and a polishing apparatus, in particular, a pad conditioner which recovers a surface of a polishing pad in a polishing apparatus for polishing a work such as a semiconductor wafer, a pad conditioning method, and a polishing apparatus which is provided with the pad conditioner.
2. Description of the Related Art
As microstructure and multilayered structure of a semiconductor device have been achieved, CMP (Chemical Mechanical Polishing) technology has become essential in a manufacturing process of the semiconductor device. The CMP technology is now used for planarization of an insulating film between layers, as well as in various processes of Cu wiring and isolation of elements, for example.
In the CMP technology for planarization, removal rate uniformity (polishing uniformity) across a work surface is an important specification. In order to improve the polishing uniformity, it is important to uniformly distribute any elements which affect the removal rate across a work surface.
While such important elements include a polishing pressure and a relative velocity in polishing, a surface state of a polishing pad is also an important element quantification of which is still in a preliminary stage. A preferable surface state of a polishing pad is achieved by conditioning the polishing pad. Also, a fact that, in a so-called in-situ conditioning in which a pad is conditioned during polishing, for example a stopping of the conditioning suddenly drops a removal rate, shows that a precise control of a surface state of a polishing pad is important.
Pad conditioning is an act to bring a pad conditioner (hereinafter, it may be simply referred to as a conditioner) having grinders such as diamond into contact with a polishing pad to scrape or roughen a surface of the polishing pad, so that a surface state of a new polishing pad is optimized as an initial state with a good holding capacity of the slurry or the slurry holding capacity of the polishing pad in use is recovered to maintain its polishing capability.
Conventionally, pad conditioners having diamond abrasive particles electro-deposited thereto have been often used to condition a polishing pad by being pressed against the polishing pad while rotating around its central axis (for example, see Japanese Patent Application Laid-Open No. 2001-274122 and corresponding U.S. Pat. No. 6,623,344, or Japanese Patent Application Laid-Open No. 2003-181756).
FIG. 12 is a conceptual view to illustrate a pad conditioner described in Japanese Patent Application Laid-Open No. 2001-274122 and corresponding U.S. Pat. No. 6,623,344. The pad conditioner 130 described in Japanese Patent Application Laid-Open No. 2001-274122 and corresponding U.S. Pat. No. 6,623,344 includes, as shown in FIG. 12, a substrate 131 having diamond abrasive particles 133 electro-deposited thereto, and a supporting section 132 to which the substrate 131 is fixedly attached.
FIG. 13 is a conceptual view to illustrate a pad conditioner described in Japanese Patent Application Laid-Open No. 2003-181756. The pad conditioner 130A described in Japanese Patent Application Laid-Open No. 2003-181756 in principle includes a substrate 131A, diamond abrasive particles 133 which are electro-deposited to the substrate 131A, and a supporting section 132A, and the substrate 131A is swingably mounted to the supporting section 132A in every direction, via a so-called gimbal arrangement of a ball joint 132a for example, so as to follow a surface of a polishing pad 20.
Apparatuses having a brush conditioner in addition to a diamond conditioner are also known (for example, see Japanese Patent Application Laid-Open No. 2003-211355 and corresponding U.S. Pat. No. 6,953,390). Japanese Patent Application Laid-Open No. 2003-211355 and corresponding U.S. Pat. No. 6,953,390 disclose a diamond conditioner for scraping a polishing pad surface as a first conditioner and a brush conditioner for extracting foreign matters clogged in recesses in the polishing pad surface as a second conditioner.
Since the brush conditioner is for extracting foreign matters clogged in recesses in the polishing pad surface, it is the diamond conditioner of the first conditioner which conditions the pad.
The brush conditioner has a nylon brush as a brushing member. The nylon brush can brush a pad surface, but is not effective for scraping the pad surface.
Thus, in the technology disclosed in the above document, the brush conditioner is used as a device only for removing foreign matters in a pad surface, not for scraping and conditioning the pad surface with a brush.
Other than the above, there is another document which describes about conditioning by use of brush (for example, see the above Japanese Patent Application Laid-Open No. 2003-181756 or Japanese Patent Application Laid-Open No. 10-329003). However, both brushes described in Japanese Patent Application Laid-Open No. 2003-181756 and Japanese Patent Application Laid-Open No. 10-329003, as well as the one in Japanese Patent Application Laid-Open No. 2003-211355 and corresponding U.S. Pat. No. 6,953,390, are described to use in a brushing method for extracting foreign matters in a pad surface, not to use in a conditioning method for scraping a surface of a polishing pad.
A polishing pad used in a CMP apparatus has a surface which is not flat when the pad is attached to a polishing plate, because the thickness of the polishing pad itself is uneven or the polishing pad is attached to the polishing plate unevenly. A surface of a polishing pad attached to a polishing plate usually has a height difference of 30 μm to 50 μm.
However, in CMP, in order to uniformly polish a wafer surface, a uniform conditioning over a polishing pad surface having such unevenness is required by following such a surface with a pad conditioner.
FIG. 11 is a view to show a concept of a pad conditioning specification required in CMP. As shown in FIG. 11, when a polishing pad 20 having the waviness with a height difference of 50 μm for a width of about 100 mm is conditioned for example, a uniform conditioning by following the waviness is required. Since a polishing pad is made of an elastic material in this way, such a pad conditioning in a CMP apparatus is considered to be a reference grinding process on an elastic material.
Whereas, the pad conditioner 130 described in Japanese Patent Application Laid-Open No. 2001-274122 and corresponding U.S. Pat. No. 6,623,344 is completely fixed to the supporting section 132, and this configuration allows only the top portion of a waviness of a polishing pad surface to be scraped. Thus, the pad conditioner 130 has a problem that a uniform conditioning by following a polishing pad surface cannot be achieved.
The pad conditioner 130A described in Japanese Patent Application Laid-Open No. 2003-181756 has a conditioning surface which is supported to follow a polishing pad surface, but in an actual pad conditioning, a uniform conditioning by following a polishing pad surface cannot be achieved. This is because the pad conditioner is positioned at an angle to the polishing pad 20 due to a large frictional force applied to the pad conditioner surface in contact with the polishing pad 20 which is moving at a high speed. The positioning at an angle makes the frictional force to be decreased, and the pad conditioner returns to its original posture, thereby the pad conditioner discontinuously contacts the polishing pad 20 (stick-slip).
The following problems on the polishing performance of the wafer are caused by the ununiformity (unevenness) of the conditioning in the polishing pad surface. The polishing ununiformity (polishing unevenness) is occurred because there are a conditioned portion and an unconditioned portion in the polishing pad surface. Next, in the step of stabilizing the polishing rate, the entire polishing pad surface is not conditioned evenly and the conditioning is made to partially progress, so that stabilizing the polishing rate takes long time. The polishing pad in which the polishing rate is yet stabilized, can not subject a product wafer to the polishing processing. As a result, the startup time of the polishing pad takes long.
In case of pad conditioning is an act to bring the conventional plate type pad conditioner to which diamonds are electro-deposited into contact with a polishing pad, the pad conditioner is positioned at an angle to the polishing pad due to a large frictional force applied to the pad conditioner surface in contact with the polishing pad which is moving at a high speed. The positioning at an angle makes the frictional force to be decreased, and the pad conditioner returns to its original posture, thereby the pad conditioner discontinuously contacts the polishing pad. In this way, the conditioning of the polishing pad in a circumferential direction is performed unevenly. The problems caused by the uniformity of the conditioning are not limited to the above described.
The size of the scrapes of the polishing pad scraped by conditioning varies greatly, since the portions of small scrapes and large scrapes are generated because the pad conditioner discontinuously contacts the polishing pad. The surface of the polishing pad is scraped as exfoliated a big pieces not stably scraped by small amount, accordingly, the scrapes volume of the polishing pad by the conditioning enlarges. As a result, the consumption amount of the pad surface is increased, leading to a problem that the life of the polishing pad is short and then the replacement cycle of the polishing pad is also short. In this way, conventional pad conditioners have an essential problem in their structures from the point of view of a reference grinding over an elastic body.
Prior to the present invention, the inventor of the present invention made a study to assess the effect of a pad conditioning. First, a recovery of a removal rate of a clogged polishing pad was evaluated by brushing a surface of the polishing pad with a nylon brush while pure water being supplied to the pad without scraping the polishing pad surface. As a result, the removal rate recovered not more than 31.4% in spite of the pure water supply and brushing for a long time of period, where it was observed under SEM that foreign matters in the polishing pad surface were completely removed from the polishing pad surface (related document: Daichi Kamikawa and Takashi Fujita et al., Proceedings of the 2004 Japan Society for Precision Engineering Conference, Tohoku Regional Branch, p. 22).
The above experiment shows that such a brushing only removes foreign matter remaining on a surface of a polishing pad, but does not condition a pad. The inventor of the present invention confirmed that the removal rate recovers with a usual conditioning using diamonds for scraping the polishing pad surface after the brushing, and concluded that a scraping of a polishing pad surface is necessary for a pad conditioning.
In addition, the inventor of the present invention verified that a surface of a polishing pad is chemically modified when a removal rate of the polishing pad is decreased due to clogging. The inventor of the present invention also confirmed that scraping the diverse material partially recovers the removal rate. This result suggests that a removal rate decreases not only when foreign matters are deposited in pores of a polishing pad, but also when the polishing pad surface chemically modifies (related document: Takashi Fujita, Proceedings of the 2005 Japan Society for Precision Engineering Conference, Spring, p. 845).
In this way, the inventor of the present invention confirmed that extracting foreign matters in a polishing pad surface is not sufficient as a conditioning to maintain a removal rate, and scraping the modified pad surface is essential.
A conditioning in terms of scraping a polishing pad surface is already achieved with a conditioning plate of the first conditioner to which diamonds are electro-deposited, in the above Japanese Patent Application Laid-Open No. 2003-211355 and corresponding U.S. Pat. No. 6,953,390, for example.
The above description shows that a pad conditioning which includes scraping a polishing pad surface by following a surface of the polishing pad, that is, finely grinding the polishing pad is indispensable.
However, a pad conditioning is not just a scraping of a polishing pad surface. Roughening the polishing pad surface during the scraping is also necessary, and when the surface is carved with a tool such as a plane without roughening, the slurry holding capacity of the polishing pad is degraded, which is not a result of conditioning to obtain. In conditioning, it is important to scrape a pad surface while a microscopically rough surface being formed which is required to improve or maintain the slurry holding capability of the pad.
When a finely-scraped, microscopically rough surface of a polishing pad is achieved by conditioning, the modified portion of the polishing pad surface is effectively removed, and a substantial surface area for holding slurry is increased in the polishing pad surface, which allows a sufficiently high removal rate to be ensured.
Because the polishing pad is an object to be processed which is made of a polymer composite resin material and of a material having a number of air bubbles in its surface, the process to achieve a microscopically rough surface of a polishing pad is very different from a grinding in a usual metal processing or ceramic processing. In grinding a porous resin material with abrasive particles, a size of the abrasive particles, a tip shape of the abrasive particles, and the like should be carefully designed so as not to tear off the surface by the particles cutting into the surface.
In a conventional pad conditioning, a plate to which diamonds are electro-deposited is pressed against a polishing pad. As a result, a polishing pad surface is scraped by the moving diamonds of the plate. However, since the diamonds electro-deposited to the plate do not cut into the pad enough under a low pressure, a somewhat higher pressure is applied to press down the plate for conditioning. Therefore, the plate roughens a polishing pad surface while grinding, but eventually it scrapes the surface too much due to the higher presser, and shortens the life of the polishing pad.
Prior to the present invention, the inventor of the present invention first roughened a polishing pad surface with a tool having a tiny needle to which diamonds are electro-deposited. The inventor confirmed a result that the surface was quite effectively scraped, and observed under SEM that the surface was effectively microscopically roughened despite the surface of the polishing pad being also a porous resin material.
However, as described above, in the case of a conditioner using a conventional conditioning plate, the conditioning plates is positioned at an angle to a polishing pad due to a frictional force between the polishing pad and the conditioner, and the positioning at an angle makes the frictional force to be decreased, and the pad conditioner returns to its original posture, thereby a conditioning is performed by the pad conditioner which discontinuously contacts the polishing pad.
With respect to the discontinuous contact, a report about an actual research has been issued (See Ara philipossian, Zhonglin Li, Hyosang Lee, Len Borucki, Ryozo Kimura, Naoki Rikita and Kenji Nagasawa, Effect of Diamond Disc Conditioner Design and Kinematics on Process Hydrodynamics during Copper CMP, Proceedings of CMP-MIC conference (2005) p. 43, T. P. Merchanr, J. N. Zabasajja, L. J. Borucki, A. Scott Lawing, A Pad Wear Model For CMP Process Optimization, Proceedings of CMP-MIC Conference (2005) p. 143-150).
In the report, a tilting of a pad is mentioned in which a conditioner tilts relative to a pad due to a frictional force when a small vertical load is applied to a conditioner, and the moving of a conditioning plate is analyzed in consideration of the tilting.
The inventor of the present invention also conditioned a pad using a conditioning plate of the prior art under a flexible joint mechanism. In the conditioning, the inventor of the present invention applied a coating over the polishing pad surface to evaluate the conditioning uniformity based on the amount of the removed coating.
The result of the above evaluation, as shown in FIG. 9, clearly shows that the polishing pad surface was unevenly conditioned using the conventional conditioning mechanism. This obviously means that the polishing pad surface was unevenly polished because the conditioner discontinuously contacted the pad as described above and also the uneven thickness of the polishing pad or uneven attachment of the polishing pad affected the polishing.

Pad conditioner, pad conditioning method, and polishing apparatus


A key management apparatus which can be used to encrypt/decrypt content data in a content playback device includes a storing unit for storing a secret key, a key information decrypting unit for decrypting encrypted key information and an updating unit operable to update the secret key with an algorithm stored therein, when the decrypted key information is key-updating information. Seed information can be received for use with the algorithm to provide a new secret key, and preliminary trigger information can be used to poll a group of appliances to request key information to determine any duplication of appliances.

In MPEG-2 Systems (ISO/IEC13818-1), which is a standard conditional access system, the distributor transmits contents including images and audio after scrambling them with a scrambling key Ks. The receiver plays back the contents after descrambling them with a scrambling key Ks. At this time, the distributor and the receiver each need to have the same scrambling key Ks.
The distributor therefore stores the scrambling key Ks into a piece of information called ECM (Entitlement Control Messages), and transmits the ECM after encrypting them with a work key Kw. Further, the distributor stores the work key Kw into a piece of information called EMM (Entitlement Management Messages), and transmits the EMM after encrypting them with a master key Km which is unique to each playback apparatus.
The receiver decrypts the EMM using the master key Km that is of its own to obtain the work key Kw, and then decrypts the ECM using the work key Kw to obtain the scrambling key Ks. This way, the distributor and the receiver each have the same scrambling key Ks.
FIG. 1 shows the general structure of the conditional access system.
The broadcast apparatus 101 multiplexes and transmits to the playback apparatus 102 by broadcast, various kinds of information including scrambled contents, ECM, EMM. The playback apparatus 102 descrambles/decrypts the information and displays it on a display monitor 103. At this time, the playback apparatus 102 performs decryption with use of an ID and a master key Km stored in the playback apparatus itself, and then descrambles the scrambled contents. A different ID is assigned to each playback apparatus, each manufacturer, or else, as necessary. Also, a different master key Km is assigned to each playback apparatus, each manufacturer, or else, as necessary. The master keys correspond one-to-one with the IDs.
FIG. 2 shows the structure of the playback apparatus in the conditional access system.
In the playback apparatus 201, the receiving unit 202 receives various kinds of information including scrambled contents, ECM, EMM, and the type judging unit 203 judges the types of information. The type judging unit 203 transfers information to different units depending on what type of information it is; for example, it transfers scrambled contents to the content descrambling unit 211, ECM to the ECM decrypting unit 208, and EMM to the EMM decrypting unit 205.
The ID/Km storing unit 204 stores an ID and a master key that are unique to the playback apparatus 201. The EMM decrypting unit 205 decrypts EMM with the master key Km, and inputs, to the Kw updating unit 206, a work key Kw which has been a part of the decrypted EMM. The Kw updating unit 206 obtains the work key Kw from the EMM decrypting unit 205 and updates the existing work key Kw. The Kw storing unit 207 stores the work key Kw that has been updated by the Kw updating unit 206.
There is also another example where, in order to update an existing work key, a new work key is obtained through a bi-directional communication system. (e.g. see Japanese Unexamined Patent Application Publication No. 2002-16901)
The ECM decrypting unit 208 decrypts ECM with the work key Kw, and inputs, to the Ks updating unit 209, a scrambling key Ks which has been a part of the decrypted ECM. The Ks updating unit 209 obtains the scrambling key Ks from the ECM decrypting unit 208 and updates the existing scrambling key Ks.
Here, updating of the work key Kw and the scrambling key Ks usually means to overwrite them; however, it is acceptable to make additions to the work key and the scrambling key.
The Ks storing unit 210 stores the scrambling key Ks that has been updated by the Ks updating unit 209. The content descrambling unit 211 descrambles the scrambled contents using the scrambling key Ks, and inputs the descrambled contents to the content outputting unit 212. The content outputting unit 212 transmits the contents to the display monitor.
FIG. 3 shows the operation of the playback apparatus in the conditional access system.
The playback apparatus receives EMM from the broadcast apparatus (S301). The EMM include (i) an ID of a playback apparatus that is to receive the EMM and (ii) an encrypted work key E(Kw, Km) which is a work key Kw encrypted with a master key Km that corresponds to the ID. Here and hereafter, E(X, Y) denotes "information X encrypted with the key Y" or "information X scrambled with the key Y".
The playback apparatus decrypts E(Kw, Km) using a Km stored in the playback apparatus itself, if the ID included in EMM coincides with the ID stored in the playback apparatus itself. As a result, the playback apparatus obtains the work key Kw (S302).
Next, the playback apparatus receives ECM from the broadcast apparatus (S303). The ECM include an encrypted scrambling key E (Ks, Kw) which is a scrambling key Ks encrypted with a work key Kw.
The playback apparatus decrypts E (Ks, Kw) using the work key Kw stored in the playback apparatus itself. As a result, the playback apparatus obtains the scrambling key Ks (S304).
Further, the playback apparatus receives a scrambled content E(Content, Ks) from the broadcast apparatus (S305).
The playback apparatus descrambles E(Content, Ks) using the scrambling key Ks stored in the playback apparatus itself. As a result, the playback apparatus obtains the content (S306) and the user is able to view the content.
FIG. 4 shows the general structure of the conditional access system in which there are a plurality of playback apparatuses.
The playback apparatus 1 and the playback apparatus 2 receive various kinds of information transmitted from the broadcast apparatus 101. A display monitor is omitted from the drawing. The ID1 and the ID2 are assigned to each of the playback apparatuses respectively and are different from each other. Since IDs correspond one-to-one with master keys Kms, Km1 and Km2 are different from each other as well. Here, a different ID is assigned to each playback apparatus, but it is also acceptable if a different ID is assigned to each manufacturer, each model of playback apparatuses, each production lot, or each specific group. In such cases, a plurality of playback apparatuses within a group have the same IDs and master keys Kms, but those IDs and master keys are different from IDs and master keys owned by playback apparatuses in another group.
FIG. 5 shows the operation of the plurality of playback apparatus in the conditional access system.
The playback apparatus 1 selectively receives EMM 1 from the broadcast apparatus (S501). EMM 1 includes the ID1 and an encrypted work key E(Kw, Km1) which is a work key Kw encrypted with the master key Km1 that corresponds to the ID1. Because of the ID1 included in EMM 1, the playback apparatus 1 is able to identify that this particular set of EMM is addressed to the playback apparatus 1 itself.
The playback apparatus 1 decrypts E(Kw, Km1) using the Km1 stored in the playback apparatus 1 itself. As a result, the playback apparatus 1 obtains the work key Kw (S502).
The playback apparatus 2 selectively receives EMM 2 from the broadcast apparatus (S503). EMM 2 include ID2 and an encrypted work key E(Kw, Km2) which is the work key Kw encrypted with the master key Km2 that corresponds to ID2. Because of the ID2 included in EMM 2, the playback apparatus 2 is able to identify that this particular set of EMM is addressed to the playback apparatus 2 itself.
The playback apparatus 2 decrypts E(Kw, Km2) using the Km2 stored in the playback apparatus 2 itself. As a result, the playback apparatus 2 obtains the work key Kw (S504).
This is how the playback apparatus 1 and the playback apparatus 2 each obtain the work key Kw. The procedure after this is the same as the one described in FIG. 3; therefore, explanation will be omitted.
The following describe a method of preventing an unauthorized apparatus from playing back contents, when there is one.
FIG. 6 shows the general structure of the conditional access system in which there is an unauthorized apparatus.
The unauthorized playback apparatus is a playback apparatus that disguises itself as the playback apparatus 2 with ID2 and the master Key Km2 having been obtained in an unauthorized fashion. In this situation, the unauthorized apparatus is able to pretend as if it was the playback apparatus 2 and play back the contents, by the same procedure of operations shown in FIG. 5.
Here is a method by which the broadcast apparatus does hot transmit EMM that include the ID2 so that it is possible to prevent unauthorized playback of contents when it has been learned that an unauthorized apparatus exists.
FIG. 7 shows the operation of the playback apparatuses at times of preventing an unauthorized apparatus from performing unauthorized playback of contents.
FIG. 7 differs from FIG. 5 in that the broadcast apparatus transmits only EMM 1 intended for the playback apparatus 1 (S501), and does not transmit EMM2 which are intended for the playback apparatus 2. This way, the unauthorized apparatus is not able to obtain the work key Kw. As a result, the unauthorized playback apparatus is not able to obtain a scrambling key Ks (S701), and is not able to receive the contents, either (S702).
There is, however, a problem in this method since the broadcast apparatus does not transmit EMM that include the ID2. —The playback apparatus 2, being an authorized apparatus, will not be able to play back the contents, either.
The first object of the present invention, therefore, is to provide a technique that makes it possible to eliminate content playback by unauthorized playback apparatus, and enable only authorized playback apparatuses to play back contents properly.
The second object of the present invention is to provide a technique that enables only authorized playback apparatus to play back contents properly by utilizing the channel through which the contents are transmitted.

Content playback apparatus method and program and key management apparatus and system

Matsushita Electric Industrial Co., Ltd.


The present invention relates generally to compositions, methods of use and kits for use as an automotive protectant composition and/or automotive cleaning composition. The protectant composition and/or cleaning composition comprises at least one surfactant and at least one rheology modifier, at least one silicone component, and water. The composition also optionally comprise, pH adjusters, builders, alkalinity sources, wetting agents, spreading agents, UV absorbers. The protectant composition has a viscosity of about 4000 to 6000 cps and exhibits a Vertical Cling parameter of between 1 and about 7 at a temperature of about 25° C. on automotive surfaces to which the compositions are applied.

Field of the Invention
The present invention relates generally to compositions, methods of use and kits for an automotive protectant exhibiting beneficial surface adhesion and application characteristics. These surface adhesion and application characteristics are measured and quantified as Vertical Cling of a composition. A composition with a very high Vertical Cling parameter, greater than 7, runs off a vertical surface very quickly which makes it difficult to get uniform coverage of a composition on vertical, sloped or angled surfaces which are common with automotive surfaces. A very low Vertical Cling parameter, less than 1, means the composition has very strong surface adhesion on vertical surfaces and will not run. Having a very low Vertical Cling parameter, it may not be beneficial because the composition may not be sprayable or it may not be easily spreadable or may not be easy to apply to surfaces and obtain uniform coverage.
The present invention also relates to a protectant composition which forms an sprayable aqueous silicone emulsion containing at least one surfactant and a rheology modifier, a silicone, and water. The composition exhibits a Vertical Cling parameter of between 1 and about 7 at a temperature of about 25° C. The present invention also relates to a method of cleaning, providing gloss and/or protecting an interior automotive surface by applying the inventive composition directly to a soiled or cleaned surface and then spreading the composition across the surface with a substrate. The substrate may be a nonwoven material comprising cellulosic fibers, modified cellulosic materials, synthetic fibers or a mixture of cellulosic or modified cellulosic and synthetic fibers. The synthetic fibers are selected from the group consisting of: polyethylene, polypropylene, and Polyethylene terephthalate (PET) and any mixture or combination thereof. In an alternate embodiment, the composition may be applied to an automotive surface using a pre-loaded wipe or substrate which is loaded with a protectant composition. Most particularly, the present invention relates to an automotive protectant and/or cleaning kit which employs a deformable container with a sprayer device that enables application of the composition to the surface to be treated where it may be spread across the surface by hand using a substrate, where the protectant composition exhibits a Vertical Cling parameter of between 1 and about 7 at a temperature of about 25° C.
The present invention pertains to sprayable silicone-containing protectant compositions used to enhance gloss and aid in protecting automotive surfaces. More particularly, the present invention pertains to protectant compositions which are aqueous silicone emulsions which provide uniform gloss and protection to surface without dripping or running. In addition, the inventive protectant composition usually contains less silicone, but yet provides comparable or higher gloss as compared to other prior art and/or commercial formulations.
Description of the Related Art
Silicone-based automotive protectants are now established products in the marketplace. By the term "automotive protectants" is meant those products which are applied to vinyl, leather, plastics, rubber, and other interior and exterior surfaces of automobiles, trucks, and other vehicles to improve the gloss of such surfaces. The protectants also to protect such surfaces from the damaging effects of uv rays, sunlight, heat, moisture, etc. Although described as "automotive protectants", the term "automotive" is not meant as a restriction on the use of these compositions, which may be equally useful on boats, trains, planes, outdoor furniture, indoor furniture etc., and also for a variety of interior uses.
The protectant may be sprayed directly onto the surface to be treated, or may be first sprayed onto a cloth, pad, or the like and then applied to the intended surface. Evaporation of the aqueous continuous phase leaves an organopolysiloxane coating which may, in some cases, penetrate polymer substrates, ameliorating loss of plasticizers from such surfaces due to exposure to sun and heat. The protectants are often formulated with UV absorbers as well, and the net effect is not only providing a glossy appearance to the vehicle or other product, but also in a general prolonging of life of leather and vinyl surfaces to which the protectant has been applied.
While lotion and paste-type protectants are available, these have not met the acceptance of sprayable formulations, due not only to their increased difficulty in application to the surface, but also due to their propensity to leave a buildup of protectant at seams, crevices, and on highly textured surfaces such as crushed leather-like vinyl. Examples of such paste and lotion-type protectants are provided by U.S. Pat. No. 5,433,890, wherein protectants containing both an aminofunctional organopolysiloxane and a polydimethylsiloxane, a film forming polymer to increase abrasion resistance, and morpholine, necessary to activate the film forming polymer are disclosed. These protectants must be left on the surface for a considerable period before wiping off the excess, and maximum effectiveness is achievable only with a second coating. The disadvantages of such preparations are readily apparent.
In Canadian published application CA 1,176,828, paste-type, organopolysiloxane emulsion-based polishes which contain a silicone-soluble UV absorbent are disclosed. These polishes have a high proportion of organopolysiloxane, greater than 20 weight percent solids, and an organic thickening agent which provides the paste-like character of the polish and serves to maintain the high level of silicone solids uniformly dispersed. However, these compositions are not sprayable, and therefore suffer the drawbacks of other pastes, creams, and lotions. Moreover, they contain a high proportion of relatively expensive organopolysiloxane.
The active ingredients of automotive protectants include silicones, which are typically organopolysiloxanes. Organopolysiloxanes are relatively expensive, and a typical protectant may contain from 20 weight percent to 40 weight percent organopolysiloxane as an aqueous emulsion. Despite the relatively high amount of organopolysiloxane, studies demonstrate that only a relatively small amount, i.e. 10% to 20% of what is applied, actually ends up on the substrate. It would be desirable to be able to lower the amount of organopolysiloxane in automotive protectants without lowering performance, or to obtain increased performance at the same level of active ingredient. Even with the same organopolysiloxane content, improved performance may allow the application rate to be lowered, resulting in greater economy to the purchaser.
Two patents, U.S. Pat. No. 6,221,433 and U.S. Pat. No. 6,206,956, by Muntz et al., describe siloxane automotive protectant compositions which contain about 10% to 20% by weight of organopolysiloxane and having comparable or improved gloss performance to comparative examples with 20% to 40% by weight of organopolysiloxane. The siloxane automotive protectants described in the Muntz patents, require that the viscosity of the emulsion be less than about 4000 cP to maintain it sprayabilty. Although these protectant formulations are an improvement over the previous protectants, there is still an opportunity to lower the amount of siloxane in the formulation to levels of less than 10% to achieve a cost savings while maintaining good gloss performance. In addition, these formulations described by Muntz have a viscosity of less than 4000 cps and do not exhibit good vertical cling and have a tendency to drip and run off of surfaces.
Accordingly, there is a need in the art for improved protectant compositions and methods of using said protectants which will provide good gloss and protection of automotive surfaces with low amounts of silicone and which have improved application and vertical cling properties so that they can be uniformly applied to surfaces without dripping and running.

Automotive protectant compositions with improved vertical cling


A method and device for optimal processing of a plurality of sets of coherent states of lights. The method includes: receiving a light having a coherent state; splitting the coherent state into a plurality of identical states (slices), each a coherent state with lower intensity than that of the received coherent state; transferring the information of each of the identical coherent states into a qubit; compressing the quantum information of the qubit into a quantum memory; and quantum processing the quantum information from the quantum memory.

Quantum information is physical information that is held in the state of a quantum system. The unit of quantum information may be a qubit, a two-level quantum system. In contrast to discrete classical digital states, a two-state quantum system can be in a superposition of the two states at any given time. Unlike classical information, quantum information cannot be read without the state being disturbed by the measurement device. Furthermore, in quantum information, an arbitrary state cannot be cloned.
Coherent states of light, such as those of laser light waveforms, are widely used for communication and sensing applications, so the optimal discrimination of coherent states, that is, the quantum states of light emitted by a laser, has immense practical importance. However, quantum mechanics imposes a fundamental limit on how well different coherent states can be distinguished, even with perfect detectors, and limits such discrimination to have a finite minimum probability of error. While conventional optical detection schemes lead to error rates well above this fundamental limit, an explicit receiver design involving feedback and photon counting that can achieve the minimum probability of error has been proposed. However, this receiver design only applies to a set of two coherent states (the binary case) and the generalization of this proposed design to larger sets of coherent states has proven to be challenging, thereby suggesting that this may be a limitation inherent to proposed linear-optics-based adaptive measurement strategy.
Helstrom (cited reference [1] on page 4 of Appendix I) provided a set of necessary and sufficient conditions on the measurement that yields the minimum average probability of error in discriminating M≧2 distinct quantum states. However, for optical state discrimination, this mathematical specification of measurement operators does not usually translate into an explicit receiver specification realizable using standard optical components, thus leaving a gap between the minimum error probability (the Helstrom limit) and the minimum achievable by conventional measurements, viz., homodyne, heterodyne, and direct detection.
For discriminating two coherent states, Dolinar proposed a receiver that achieves the Helstrom limit exactly for discriminating any two coherent state signals (Cited references [2] and [12] on pages 4 and 5 of Appendix I). This proposed receiver works by applying one of two time-varying optical feedback waveforms to the laser pulse being detected, and instantaneous switching between the two feedback signals at each click event at a shot-noise-limited photon counter. More recently, it has been shown that two coherent states can be optimally distinguished using linear-optical processing followed by adaptive measurements. For discriminating between multiple (M>2) coherent states, there is yet no optical receiver known which achieves the Helstrom limit.
A number of sub-optimal receivers for the M>2 case have been proposed with a common philosophy—that of "slicing" a coherent-state pulse into smaller coherent-states, detecting each slice via photon counting after coherent addition of a local field, and feeding forward the detection outcome to the processing of the next slice, as illustrated in FIG. 1. The Dolinar receiver functions by slicing the coherent state, but instead of compressing all the information content of the slices, it measures each slice individually and feeds information about the measurement forward to the measurement of the other slices. After the final measurement, this receiver is able to determine which state was transmitted with a minimum probability of error allowed by quantum mechanics. The main disadvantages of the Dolinar receiver are that: 1) it can only optimally distinguish between two coherent states, 2) it only optimizes the probability of error and cannot be easily adapted to optimize a different figure of merit, and 3) it results in a classical decision, not quantum states, accordingly, its results cannot be further optimally processed by a quantum device/computer. That is, making a classical decision corresponds to making a measurement, which destroys some information which could be useful for additional quantum processing. Thus, making a classical decision is akin to not fully utilizing the information that is in the quantum states, and thus additional processing after a classical decision may be suboptimal.
A quantum computer makes direct use of quantum mechanical properties, such as superposition and entanglement, to perform operations on data. Contrary to digital computers, which require data to be encoded into binary digits (bits), quantum computers utilize quantum properties to represent data and perform operations on these data. Quantum computers share theoretical similarities with non-deterministic and probabilistic computers, like the ability to be in more than one state simultaneously. A quantum computer maintains a sequence of "qubits," each of which can represent a one, a zero, or any quantum superposition of these two qubit states. Additionally, a pair of qubits can be in any quantum superposition of 4 states, and three qubits in any superposition of 8.
In general, a quantum computer with n qubits can be in an arbitrary superposition of up to 2n different states simultaneously (contrasting to a classical computer that can only be in one of these 2n states at any one time). A quantum computer operates by setting the qubits in a controlled initial state that represents the hypothesis at hand and by manipulating those qubits with a fixed sequence of quantum logic gates. The calculation may end with measurement of all the states, collapsing each qubit into one of the two pure states, so the outcome can be at most n classical bits of information. Alternatively, the qubits may be stored in a quantum memory for further quantum processing.
Recent research shows that any optical receiver involving the most general coherent-state feedback, passive linear optics and photon counting cannot attain the quantum-limited channel capacity of an optical channel to carry classical information. The fact that such generalizations of Dolinar's optimal binary receiver to larger sets of coherent states has proven to be challenging, and the above result on the limitation of general coherent optical receivers, suggest that this may be a limitation inherent to the linear-optics-based adaptive measurement approach, and that the binary discrimination case is somehow special.

Device and method for optimally distinguishing among an arbitrary set of coherent states of light


Earth-boring rotary drill bits including a bit body attached to a shank assembly at a joint. In some embodiments, the joint may be configured to carry at least a portion of any tensile longitudinal and rotational load applied to the drill bit by mechanical interference at the joint. In additional embodiments, the joint may be configured to carry a selected portion of any tensile longitudinal load applied to the drill bit. Methods for attaching a shank assembly to a bit body of an earth-boring rotary drill bit include configuring a joint to carry at least a portion of any tensile longitudinal and rotational load applied to the drill bit by mechanical interference. Additional embodiments include configuring a joint to carry a selected portion of any tensile longitudinal load applied to the drill bit by mechanical interference.

Rotary drill bits are commonly used for drilling bore holes or wells in earth formations. One type of rotary drill bit is the fixed-cutter bit (often referred to as a "drag" bit), which typically includes a plurality of cutting elements secured to a face region of a bit body. The bit body of a rotary drill bit may be formed from steel. Alternatively, the bit body may be formed from a conventional particle-matrix composite material 15. A conventional earth-boring rotary drill bit 10 is shown in FIG. 1 that includes a bit body 12 comprising a particle-matrix composite material 15. The bit body 12 is secured to a steel shank 20 having a threaded connection portion 28 (e.g., an American Petroleum Institute (API) threaded connection portion) for attaching the drill bit 10 to a drill string (not shown). The bit body 12 includes a crown 14 and a steel blank 16. The steel blank 16 is partially embedded in the crown 14. The crown 14 includes a particle-matrix composite material 15, such as, for example, particles of tungsten carbide embedded in a copper alloy matrix material. The bit body 12 is secured to the steel shank 20 by way of a threaded connection 22 and a weld 24 extending around the drill bit 10 on an exterior surface thereof along an interface between the bit body 12 and the steel shank 20.
The bit body 12 further includes wings or blades 30 that are separated by junk slots 32. Internal fluid passageways (not shown) extend between a face 18 of the bit body 12 and a longitudinal bore 40, which extends through the steel shank 20 and partially through the bit body 12. Nozzle inserts (not shown) also may be provided at the face 18 of the bit body 12 within the internal fluid passageways.
A plurality of cutting elements 34 is attached to the face 18 of the bit body 12. Generally, the cutting elements 34 of a fixed-cutter type drill bit have either a disk shape or a substantially cylindrical shape. A cutting surface 35 comprising a hard, super-abrasive material, such as mutually bound particles of polycrystalline diamond, may be provided on a substantially circular end surface of each cutting element 34. Such cutting elements 34 are often referred to as "polycrystalline diamond compact" (PDC) cutting elements 34. The PDC cutting elements 34 may be provided along the blades 30 within pockets 36 formed in the face 18 of the bit body 12, and may be supported from behind by buttresses 38, which may be integrally formed with the crown 14 of the bit body 12. Typically, the cutting elements 34 are fabricated separately from the bit body 12 and secured within the pockets 36 formed in the outer surface of the bit body 12. A bonding material such as an adhesive or, more typically, a braze alloy may be used to secure the cutting elements 34 to the bit body 12.
During drilling operations, the drill bit 10 is secured to the end of a drill string, which includes tubular pipe and equipment segments coupled end to end between the drill bit 10 and other drilling equipment at the surface. The drill bit 10 is positioned at the bottom of a well bore hole such that the cutting elements 34 are adjacent the earth formation to be drilled. Equipment such as a rotary table or top drive may be used for rotating the drill string and the drill bit 10 within the bore hole. Alternatively, the shank 20 of the drill bit 10 may be coupled directly to the drive shaft of a down-hole motor, which then may be used to rotate the drill bit 10. As the drill bit 10 is rotated, drilling fluid is pumped to the face 18 of the bit body 12 through the longitudinal bore 40 and the internal fluid passageways (not shown). Rotation of the drill bit 10 under weight applied through the drill string causes the cutting elements 34 to scrape across and shear away the surface of the underlying formation. The formation cuttings mix with and are suspended within the drilling fluid and pass through the junk slots 32 and the annular space between the well bore hole and the drill string to the surface of the earth formation.
Conventionally, bit bodies that include a particle-matrix composite material 15, such as the previously described bit body 12, have been fabricated in graphite molds using a so-called "infiltration" process. The cavities of the graphite molds are conventionally machined with a multi-axis machine tool. Fine features are then added to the cavity of the graphite mold using hand-held tools. Additional clay work also may be required to obtain the desired configuration of some features of the bit body. Where necessary, preform elements or displacements (which may comprise ceramic components, graphite components, or resin-coated sand compact components) may be positioned within the mold and used to define the internal passages, cutting element pockets 36, junk slots 32, and other external topographic features of the bit body 12. The cavity of the graphite mold is filled with hard particulate carbide material (such as tungsten carbide, titanium carbide, tantalum carbide, etc.). The preformed steel blank 16 may then be positioned in the mold at the appropriate location and orientation. The steel blank 16 typically is at least partially submerged in the particulate carbide material within the mold.
The mold then may be vibrated or the particles otherwise packed to decrease the amount of space between adjacent particles of the particulate carbide material. A matrix material (often referred to as a "binder" material), such as a copper-based alloy, may be melted, and caused or allowed to infiltrate the particulate carbide material within the mold cavity. The mold and bit body 12 are allowed to cool to solidify the matrix material. The steel blank 16 is bonded to the particle-matrix composite material 15 forming the crown 14 upon cooling of the bit body 12 and solidification of the matrix material. Once the bit body 12 has cooled, the bit body 12 is removed from the mold and any displacements are removed from the bit body 12. Destruction of the graphite mold typically is required to remove the bit body 12 therefrom.
The PDC cutting elements 34 may be bonded to the face 18 of the bit body 12 after the bit body 12 has been cast by, for example, brazing, mechanical, or adhesive affixation. Alternatively, the cutting elements 34 may be bonded to the face 18 of the bit body 12 during furnacing of the bit body if thermally stable synthetic or natural diamonds are employed in the cutting elements 34.
After the bit body 12 has been formed, the bit body 12 may be secured to the steel shank 20. As the particle-matrix composite materials 15 typically used to form the crown 14 are relatively hard and not easily machined, the steel blank 16 is used to secure the bit body 12 to the shank 20. Complementary threads may be machined on exposed surfaces of the steel blank 16 and the shank 20 to provide the threaded connection 22 therebetween. The steel shank 20 may be threaded onto the bit body 12, and the weld 24 then may be provided along the interface between the bit body 12 and the steel shank 20.

Methods of attaching a shank to a body of an earth-boring tool including a load-bearing joint and tools formed by such methods


A bill payment provider offers to a customer an option to pay a bill from a biller using a payment card account. The offering is carried out via a mechanism of the bill payment provider. The mechanism is of a kind which normally facilitates payments via electronic funds transfer from a demand deposit account of the customer. A request to pay the bill using the payment card account is received via the mechanism. Payment of the bill using the payment card account is facilitated by formatting and dispatching a message from the bill payment provider to an electronic bill payment system. The message is flagged with a flag indicating that the message comprises a non-financial, card payment, message. The message includes an identification of the biller, a card number of the payment card account, and an expiration date of the payment card account. The message is an electronic funds transfer message augmented with the flag, the card number, and the expiration date. An alternative technique using an operator of a payment network is also disclosed, as are corresponding systems.

Movement of consumer bill payments from paper to electronic methods continues to increase. Using methods such as Automated Clearing House (ACH), debit, credit, and online banking, electronic bill payments have gone from 22% in 2001 to 45% in 2005, according to the American Bankers Association, Dove Consulting, US Consumer payment trends 2005. Furthermore, according to a recent E SOURCE market research study, PRNewswire, E SOURCE, 2008 Self-Service Customer Care Market Research Study, 51% of Internet users in the U.S. and Canada now pay at least one monthly bill online, which represents a substantial increase over the results of the company's 2004 research that indicated only 33% of Internet users were making online payments.

Apparatus and method for bill payment card enrollment


An artificial ligament 12 comprises a ligament section 12 having a long narrow shape, and coupling sections provided on both ends. The coupling sections comprise balls which are fixed at both ends of the ligament section, and holding body in which a holding space is formed within the inner section by means of cap section covering the holding body base section so as to hold the balls in a slidable manner. Attachment holes are formed in the bones of the joint, and the coupling sections are fixed by being screwed into the attachment holes. After transplantation of this ligament, there is no damage to the artificial ligament when the joint is extended, and long lasting use can be expected.

1. Field of the Invention
The present invention relates to an artificial ligament for transplantation to a joint such as the knee, ankle, or elbow which has lost its ligament.
2. Description of the Related Art
For athletes who participate in sports such as soccer, rugby and skiing in which movement is very intense, injuries to the ligaments of joints such as the knee, ankle, or elbow are numerous. In particular, when these ligaments are severed, transplantation of artificially made ligament or ligament taken from a living body is carried out for strengthening purposes and the like.
When these types of artificial ligament are transplanted, as shown in FIG. 7, firstly, holes 2 for attaching an artificial ligament 1 are formed in the vicinity of the joint of bones B which are to be connected by means of the artificial ligament 1, the artificial ligament 1 is inserted through these holes 2, and both ends thereof are fixed to bones B by means of staples 3.
However, when an artificial ligament 1 is transplanted in the above way, for example, the artificial ligament 1 makes contact with and rubs on the peripheral section 2a of the opening of holes 2 formed in bones B for the purpose of attachment, and there is concern that the artificial ligament 1 will be damaged due to this friction. In addition, there is the problem that, due to repetitive bending of the artificial ligament 1 at these peripheral sections 2a of the openings, stress is exerted on the artificial ligament 1 at these sections and damage of the artificial ligament is promoted.
Consequently, it is an object of the present invention to provide an artificial ligament which, after transplantation, is long lasting and does not become damaged even by extension of the joint.


The mechanism is to apply drive in both directions of rotation to a ring having an inside set of teeth, the drive being applied by means of a pivoting handle. The ring cooperates with two locking pawls mounted on a stationary cheekplate and with a toothed slug pivotally mounted on a cam and forming two drive pawls, the cam being pivoted by the handle, but with a certain amount of diametral clearance. When the handle is pivoted, the drive pawl corresponding to the pivot direction engages the toothed ring while the other drive pawl is held in a retracted position by a stationary slideway, and the locking pawl corresponding to the pivot direction of the handle is moved into a retracted position by the cam while the other locking pawl engages the toothed ring.

Such a control mechanism is disclosed, in particular, in document FR-A-2 717 751.
Those known control mechanisms give satisfaction, but they nevertheless suffer from the drawback of needing to be associated with a transmission mechanism generally referred to as a "locking mechanism", which enables torque to be transmitted from the handle to a downstream adjustment device, but not vice versa.
The locking mechanism represents non-negligible extra weight and extra cost.

Mechanism for controlling a rotary member by means of a pivoting handle, and a seat fitted with such a mechanism


A system and method for network support that addresses the needs of a cellular phone system which handles large volumes of information. The invention comprises a complex computer network for performing various tasks including data collection and processing, equipment inventory management, customer service, tactical surveillance, trend forecasting, modeling and other interrelated processes. The system incorporates state-of-the-art computer hardware and software into an engineering platform for providing a modular base to accommodate multiple applications as well as to ease integration of future applications.

1. Field of the Invention
This invention relates generally to information overload problems in a network, and in particular, to managing and integrating data from telephone switches, cellular phone sites and other related elements, which in the aggregate, provide cellular phone service.
2. Background of the Invention
Management of telephone switches, cellular transmission sites, and other related elements, which collectively provide cellular communication services, is very complex. The complexity is exacerbated by the myriad of network elements which generate data and by the sheer volume of the data. Information overload is an appropriate term to describe this central problem. Up until now, systems and methods in communication services have dealt with information overload by parsing out the data to multiple task handlers and manually integrating the results to achieve management and integration of the equipment and services. High integration and correlation of data from the various task handlers was impracticable or at the very least cumbersome.


A pumping device for removing liquid from a container and dispensing it in the form of a spray includes a pump attached to the upper end of a container. A pump body is engaged in the container and a piston is movable in the container and is provided with a hollow rod projecting outside of the pump. A cylindrical cap is attachable to the container and has a pivoting actuating and dispensing element provided with a dispensing nozzle communicating through a passage with a cylindrical sheath projecting inside the actuating element. The free end of the hollow rod of the pump piston engages the sheath, and the hollow rod is flexible over part of its length as measured from its free end.

The present invention relates to a pump device and method for removing a liquid from a container and dispensing it in the form of a spray.
More specifically, the present invention relates to a device of the type having a pump attached to the upper end of the container. The pump includes a pump body disposed in the container and a piston is movable in the pump body and provided with a hollow rod projecting outside of the pump. A cylindrical cap is attachable to the container and has a pivotable actuating and dispensing element provided with a dispensing nozzle communicating via a passage with a cylindrical sheath projecting inside the actuating element. The free end of the hollow rod of the pump piston engages the cylindrical sheath.
The actuating element includes at a first end a lever and at a second end a spray nozzle. The actuating element is articulated to the cap, the cap being hollowed to provide access to the opposite end of the lever-shaped actuating element, the first end also providing a bearing area for the user's finger. When the user presses down, the actuating element pivots, exerting a downward force on the hollow rod of the piston engaged by its free end in the internal cylindrical sheath of the actuating element.
The hollow rod constitutes means or structure by which the pumped liquid passes from the container to the dispensing nozzle of the cap. The axial movement of the hollow rod of the piston must be substantially if not fully linear, also keeping in mind that sufficient rigidity on the rod must be maintained to prevent any buckling as the rod moves when the actuating element pivots.
A number of solutions have been proposed to take into account off-center forces applied to the rigid hollow rod of the pump piston as a result of the pivoting movement of the actuating element.
For example, FR-A-2,682,937 proposes to connect the end of the hollow piston rod to the cylindrical sheath of the actuating element by a tubular element with flexible links. This solution requires separate fabrication of an additional built-on part to link the hollow piston rod to the actuating and dispensing element.
Also, the assignee of the present invention has proposed (in French Patent Application No. 94 00988) to manufacture the cylindrical sheath of the actuating and dispensing element in the form of a relatively long flexible passage. In practice, however, the cap and the actuating element provided with the cylindrical sheath and made in one piece therewith must be made of a relatively rigid material, such as polypropylene or high-density polyethylene. Indeed, the cap must be sufficiently rigid so that, on the one hand, it can be snapped onto the container body and, on the other hand, can ensure that the hinge area providing the articulated link of the actuating element to the cap wall is sufficiently strong to allow a large number of actuations, and finally to ensure that the lever-shaped actuating element is sufficiently rigid over its entire length.
If a rigid material is used to make an assembly including the cap and actuating element, the cylindrical sheath of the actuating element, to be sufficiently flexible, must have a very thin wall, which entails the risk of flexural breakage when the actuating element pivots.
The device known from the French patent application referred to above is possible, in practice, only with pumps such as those described in this document, requiring only a short length of travel of the hollow rod of the pump piston, and is accordingly limited in application.

Pivot-type pump having flexible liquid supply rod and method


Systems and methods for optimizing write operations to a storage device in a virtualized computing environment comprise monitoring write operations issued by an application running on a virtual machine's (VM) operating system, wherein the VM is hosted by a hypervisor providing access to a storage device in a virtualized computing environment; and causing a virtual file system (VFS) supported by the operating system to call on a first para-virtualized file system (PVFS FE) supported by the operating system to execute a write operation, in response to determining that the write operation is to write data to the storage device, wherein data that is to be written to the storage device is first written to a VM memory area allocated to the VM and accessible to the hypervisor hosting the VM.

A virtual machine (VM) is a software implementation of a machine (i.e., a computer) that executes programs like a physical machine would. Generally, access to resources in virtualized environments is associated with a high level of overhead because the VM typically cannot directly communicate with a virtualized resource. A hypervisor that hosts the VM typically has the burden of emulating the needed interface or driver on behalf of the VM. In other words, the hypervisor presents the VM with a virtual platform and monitors the execution of the VM and how the VM accesses the available hardware resources.
For example, for a VM to read or write data to a virtualized storage device, control of the read or write operations will have to be transferred between the VM and the hypervisor. The hypervisor may use any type of storage interface for storing the VM's data, including local file system, network file system, network block device, etc. In a purely emulated case, the VM has no knowledge that the provided interface (i.e., the block device) is not a real physical device, because the hypervisor emulates the interface in software. A high overhead is associated with such emulation. The operational overhead is even more costly, if there is a need for transferring control intermittently between the VM and the hypervisor during I/O operations.

Optimizing a file system interface in a virtualized computing environment

International Business Machines Corporation


A seating system configurable between a one-person and a two-person configuration, comprising a bed with front and rear portions, a bench with front and rear portions, and a backrest. The backrest is moveable between a first position immediately aft of the front bench portion whereby the seating system is in the one-person configuration, and a second position immediately aft of the rear bench portion whereby the seating system is in the two-person configuration. The rear bench portion is removable, and the seating system may be fitted with a cargo carrier in place of the rear bench portion.

This invention relates to a seating system suitable for use with a vehicle, and more particularly to a seating system that is configurable between a one-person configuration suitable for supporting one person, and a two-person configuration suitable for supporting two persons.
Seating systems for supporting people in a sitting position on a vehicle such as a snowmobile are well-known. Most vehicles include seating systems of some sort. Vehicle seating systems commonly comprise a generally horizontal bench portion secured to a supporting bed structure, and often include a generally vertical backrest immediately aft of the bench for additional comfort.
Conventional vehicle seating systems generally hold a fixed number of people. Most commonly, a vehicle seat supports only a single person. However, vehicle seats that support two people are also known. Typically, two-person seating systems are designed with an elongated bench portion so as to support one person in front of the other. Such seats typically have a backrest only for the person in the rear position, so that the person in the front position must rely on the person in the rear position for back support.
It is desirable to have the option of supporting two people on a single seat, especially in a relatively small vehicle where space and weight capacity are limited, for example a snowmobile. However, a vehicle with a conventional two-person seating system may be uncomfortable, inconvenient, or even dangerous for a single person to operate, due to the greater length of the bench and the absence of a properly positioned backrest. Furthermore, when a single person occupies a two-person seat, the excess space is wasted, as it is difficult to adapt a seat for other purposes, for example cargo space.
It is known to produce multiple seating systems for a single vehicle, for example a one-person seat and a two person seat, and to exchange seats when necessary. However, removing and replacing a seat is commonly a difficult and time-consuming operation, requiring tools and at least some mechanical expertise.
Therefore it is the general purpose of the present invention to overcome the deficiencies of the existing designs. It is the purpose of the present invention to provide a seating system suitable for use with a vehicle that is configurable between a one-person and a two-person configuration. It is preferable that the seating system be configurable quickly and conveniently. It is also preferable that, when the seating system is in the one-person configuration, the space otherwise required for supporting a second person is available for other purposes, such as cargo.
An embodiment of the present invention comprises a bed with front and rear portions, a bench with front and rear portions disposed on the bed, and a backrest disposed on the bench. The seating system is configurable between a one-person configuration suitable for supporting one person, and a two-person configuration suitable for supporting two persons. It is preferable that the backrest is moveable between a first position immediately aft of the rear bench portion, whereby the seating system is in the two-person configuration, and a second position immediately aft of the front bench portion, whereby the seating system is in the one-person configuration.
It is also preferable that the rear portion of the bench be removable when the seating system is in the one-person configuration. It is more preferable that the rear bed portion is suitable for accepting a cargo carrier when the rear bench portion is removed.
A variety of additional advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages of the inventions will be realized and attained by means of the elements and combinations particularly pointed out in the claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.

Seating system configurable between one-person to two-person configurations, and methods for configuring the same


A dynamic safe state control circuit is disclosed that controls an electrical motor based on vehicle speed. A microcontroller or other processing device is configured to control an inverter system of an electrical motor. The dynamic safe state control circuit is configured to receive a first signal that corresponds to a speed of the electric motor. The circuit is configured to activate any one of a plurality of safe states in the inverter system based on the first signal and in response to a malfunction in the microcontroller.

An electrical motor is a machine that converts electrical energy into mechanical energy. Electrical motors are employed in electric vehicles (EVs) and generate mechanical force through an interaction between a magnetic field and electric current in wire windings. The force is used to rotate a drive shaft, which in turn propels the EV. Electrical motors vary in design. Some are powered by direct current (DC) sources (e.g., batteries), while others powered by alternating current (AC) sources (e.g., the electrical grid). Electrical motors may be brushed or brushless. Electrical motors can be designed with one or more phases. The present disclosure will be described with reference to a three-phased electrical motor powered by a battery, it being understood the present disclosure should not be limited thereto. Moreover, the present disclosure will be described with reference to an electrical motor employed in an electric vehicle (EV), it being understood that present disclosure should not be limited thereto.

Dynamic safe state control of electrical motor based on vehicle speed


Channels are assigned based on co-spatial constraints in wireless network using spatial division multiple access. In one example, the invention includes assigning a co-spatial constraint to each of a plurality of conventional traffic communications channels of a base station, and receiving a request from a user terminal to communicate using a traffic communication channel of the base station. The invention further includes measuring a quality parameter of the request deriving a co-spatial constraint for the user terminal, assigning the user terminal co-spatial constraint to the user terminal, and assigning the user terminal to a traffic communication channels having a channel co-spatial constraint that is no less than the user terminal co-spatial constraint and that has no more assigned radios than permitted by the channel co-spatial constraint.

1. Field of the Invention
The present invention applies to the field of wireless communications systems using adaptive antenna arrays and, in particular, to allocating communications channels and terminals using spatial strategies in a spatial division multiplexed wireless communications system.
2. Description of the Prior Art
A typical wireless communications system is generally subdivided into cells. A cell is generally thought of as a distinct geographic area, although cells usually overlap in reality. A cell is generally associated with a base station providing service to user terminals that enter the cell, i.e., the base station's service area. Thus, a cell may also be thought of as a collection of remote terminals communicating with a particular base station at a certain time. Thus, while cells are pictured geographically, it is possible for two user terminals in close proximity to be in different cells, so long as they are communicating with different base stations of the wireless radio network.
Adaptive antenna arrays and SDMA (Spatial Division Multiple Access) enable a wireless system to use strategies to reduce interference and enhance system capacity. These strategies include 1) increasing the signal to interference ratio on the uplink (user terminal to base station) by adjusting received signal samples based on the location of a remote terminal and the RF environment, 2) concentrating signal power to the intended user terminal (beam-forming), and 3) placing nulls to user terminals using similar or the same frequency resources, such as terminals using the same channel on the downlink (base station to user terminal), among others. With these strategies, adaptive arrays can greatly enhance the capacity of a wireless system.
Using various SDMA strategies, as described above, a single base station may be able to communicate with more than one user terminal on the same conventional communications channel. The number of user terminals with which a base station can successfully communicate using a single communications channel varies. It can depend on the number of other user terminals on other channels, the nature of physical obstructions to the radio signals, the amount of RF (radio frequency) noise in the environment, and the design of particular radios and the overall system among other factors.
Prior art SDMA systems have generally used one conventional channel for one user terminal, and used the co-channel interference mitigating capabilities provided by SDMA for mitigating interference to co-channel user terminals in other cells. A co-channel user terminal can be viewed as another user terminal using the same conventional channel. For co-channel users communicating with another base station, in a different cell, the reuse frequency of the channel determines how near the co-channel users are. This affects how much co-channel interference is created. SDMA used to increase reuse frequency can increase the capacity of the system by allowing more aggressive frequency reuse.
As an alternative, the SDMA system can assign a predetermined number of user terminals to each channel. For example, three user terminals using SDMA could share each channel. Unfortunately, a system with a predetermined number of user terminals is unlikely to operate at maximum capacity, or to provide optimum quality of service. The number of co-spatial users that can successfully share a channel typically depends on the individual characteristics of each user terminal and its reception on its assigned channel. In most real systems, some user terminals will be able to successfully share a channel with more co-spatial users than others.
Therefore, using a predetermined number for co-spatial terminals will likely result in some channels being overused and some being underused. Underused channels waste capacity, and overused channels may have an unacceptably low quality of service. In order to ensure high quality service on all channels, some channels will be underused. This reduces the capacity benefits that an SDMA system can offer.

This patent is subject to a terminal disclaimer.

Channel assignment based on spatial strategies in a wireless network using adaptive antenna arrays