A slab laser amplifier with parasitic oscillation suppression has a plurality of angled pump faces related to one another in order to decrease likelihood of parasitic oscillations, with internal beam incidence angles at total internal reflection that alleviate need for reflective coatings. No polished surfaces of gain material comprising the amplifier are parallel to one another. A beam path within the gain material is such that all incident angles of the beam path upon the two main faces and the common end face are greater than a critical angle required for total internal reflection, thereby alleviating need for reflective coatings. Based on an index of refraction of the gain material, and based on a diameter of the laser beam, dimensions of the gain material are selected to maximize beam overlap in a pumped volume of the gain material.

Slab amplifiers are often used to boost output of a laser system by providing extractable energy from a pumped gain medium. The large surface area of the slab allows the pump energy to be spread over a wide volume of gain material to reduce heat effects. In general, a zig-zag pattern or tightly folded resonator (TFR) design makes use of multiple beam passes through the gain material to extract energy from the pumped region of the crystal.
Referring to FIGS. 1-6, a brief overview is provided of how a laser amplifier works in accordance with the prior art. In FIGS. 1-4, a basic laser cavity 22 includes gain material 24. The cavity 22 also has at least two mirrors 26A and 26B, such as a 100% reflective mirror 26A and a 98% partially reflective mirror 26B. The cavity 22 further has a pump energy source 28, such as a laser diode or flashlamp. FIG. 1 illustrates the cavity 22 and its components in a state of non-operation. In FIG. 2, atoms in the gain material 24 receive energy from the pump source 28, which excites the electrons into higher energy states. When these electrons return to their original energy state they emit a photon. This phenomenon is called spontaneous emission of photons.
Turning now to FIG. 3, as the photons pass through the gain material 24, they also affect the atoms in the gain material 24 by stimulating them to emit more photons while in an energized state. Mirrors 26A and 26B aligned parallel to one another at each end reflect the photons back and forth, continuing this process of stimulated emission and amplification along the same beam path. Referring to FIG. 4, photons from one atom stimulate emission of photons from other atoms and the light intensity is rapidly amplified. A cascade effect occurs, and soon we have propagated many, many photons. This process is called Light Amplification by Stimulated Emission of Radiation, which is where the term "laser" comes from. As a result of one of the end mirrors 26B having less than 100% reflectivity, some of the photons are transmitted through this mirror, and this transmitted portion is the laser's output beam.
Turning now to FIG. 5, a laser cavity 22 has limitations as to how much energy can be extracted from it, depending on available pump energy from source 28, the gain material 24, and other components. So, one way more power can be obtained is to use a second stage amplifier 30. The basic second stage amplifier 30 is much like the basic laser cavity 22, except there are no mirrors to contain the photons. There is a gain material 24 and a pump source 28 that excites the material 24 into an excited state so that there are available photons being emitted. It should be noted that there can be more than one pump source 28, which can be situated on opposite sides of the gain material 24. The large surface area of the slab allows the pump energy to be spread over a wide volume of gain material 24 to reduce localized heat effects.
Referring now to FIG. 6, the laser beam from the laser cavity 22 enters the amplifier pumped gain material 24 of the second stage amplifier 30. As was the case with the laser cavity 22 itself, photons from one atom stimulate emission of photons from other atoms and the light intensity is amplified as it passes through the amplifier gain material 24. It should be readily understood that although a single straight path of the amplified beam through the gain material 24 is shown, many amplifiers make use of a zigzag path, or tightly folded resonator (TFR) through the gain material 24 to make the best use of the excited gain material 24.
One problem encountered in the scenarios described above is that a polished uncoated air/glass interface has about 4% reflectivity. This property of gain material surfaces means that the polished parallel surfaces of the amplifier gain material can act as the mirrors of a laser cavity. This parasitic oscillation thereby depletes the available gain for the beam that we intend to amplify in the first place.
Most of the current solutions to the aforementioned issue make use of anti-reflection (AR) coatings to limit the 4% reflection effect that contributes to parasitic oscillation. Some of these solutions that make use of a zigzag beam path may also employ high-reflection coatings to facilitate reflecting the beam to be amplified off of the surfaces where desired, such as low angle of incidence beam reflections inside of the gain material.

Slab laser amplifier with parasitic oscillation suppression


An improved approach for returning aesthetically relevant search results is disclosed. A training set of images (e.g., designer-created images) is used to train a detection engine that detects items in the images as features. A classification engine is configured to analyze the features and generate classification indices for the features. A user can select an item, and the classification index for the feature corresponding to the item is retrieved. The classification index is used to identify result images, which can be returned ranked according user action data and other parameters, such as style.

In recent years, users have increasingly used image-based search sites to find items (e.g., couches, pillows, sinks, tables, clothes) which they are interested. However, images of the items are a poor substitute for the users, since they cannot inspect the items in real life (e.g., in a showroom). Thus, the users are forced to make decisions based only on the provided images and description data. Further, some users, such as clothing designers or interior designers, seek to create arrangements of items that aesthetically function together. For example, a clothing designer may select shoes, pants, a shirt, a watch, and a hat to create a stylish outfit, or an interior designer may select a couch, chair, table, vase, and floor lamp to create a living room design. While it is difficult to judge individual items using only images, it is far more complex to create an aesthetically pleasing arrangement of items using images because the user cannot examine how the items look next to one another.


A sheet manufacturing method includes a mixing step of mixing a fiber and a resin powder in air, and a sheet forming step of accumulating and heating a mixture mixed in the mixing step to form a sheet. The resin powder has a volume average particle diameter of equal to or less than 50 μm, and an absolute value of an average charging amount in a range of 5 (μC/g) to 40 (μC/g).

Accumulating a fiber-like material and causing a bonding force between the accumulated fibers to obtain a sheet-like or film-like formed body has been performed for a long time. Typical examples thereof include manufacturing paper by pulp molding (paper-forming) using water. Even in present times, pulp molding is widely used as an example of a method of manufacturing paper. The paper manufactured by pulp molding generally includes a structure by cellulose fibers derived from wood or the like being entangled with one another, and being partially bonded to one another by a binder (paper strengthening agent (such as a starch paste and a water-soluble resin)).
According to the pulp molding, it is possible for the fibers to be accumulated in a state where uniformity is favorable, and, in a case where a paper strengthening agent is used in the bonding between fibers, it is possible for the paper strengthening agent to be dispersed (distributed) in a state where the uniformity in the paper surface is good. However, because the pulp molding is a wet method, it is necessary to use large volumes of water, and the necessity of dewatering and drying, or the like, arises after forming the paper, and therefore the energy or time consumed is extremely large. It is necessary to suitably process the water used as waste water. Accordingly, it is difficult to respond to modern demands for energy savings, environmental protection, and the like. The apparatuses used in pulp molding frequently need large scale utilities such as water, power, and drainage facilities, and size reductions are difficult. From this viewpoint, there is an expectation of methods, referred to as dry methods that use no or almost no water as paper manufacturing methods in place of pulp molding.
For example, in the technology disclosed in Japanese Unexamined Patent Application Publication No. 2011-099172, an attempt at bonding fibers to one another with a thermal fusion-bondable resin in air-laid non-woven fabric that includes a highly water absorbent resin is disclosed.


A slab optical multiplexer comprises a slab substrate having two substantially flat and parallel surfaces, and internally propagating light beams. The multiplexer further comprises collimating/focusing optical elements and micro-diffractive optical elements each positioned on the surfaces in the light beams. At least one micro-diffractive optical element is positioned simultaneously in two separately incident and intersecting light beams, such that the two separately incident light beams are diffracted into a pair of co-propagating diffracted light beams.

This invention relates to optical communications technology, and particularly to a system and method for providing a slab optical multiplexer.
Multiplexers are a common optical component of telecommunications technology. These devices receive a multiplicity of input optical beams having different wavelengths and superimpose them into a common optical output beam. Traditional multiplexing devices are typically based on prism/grating and refractive lens combinations, optical band-pass filters, or waveguide coupling. For free-space light propagation, prism/grating and refractive lens combination multiplexers are used. In such devices, the lens focuses multiple beams into a single output fiber. But a single collecting lens must be relatively large to intercept all beams of interest. Hence this scheme is difficult to miniaturize. Moreover, devices comprising multiple separate optical components require difficult and time-consuming optical alignment.
In a first embodiment disclosed herein, a slab optical multiplexer is provided. The multiplexer comprises a slab substrate having two substantially flat and parallel surfaces, and internally propagating light beams. The multiplexer further comprises collimating/focusing optical elements and micro-diffractive optical elements each positioned in the light beams on the surfaces. At least one micro-diffractive optical element is positioned simultaneously in two separately incident and intersecting light beams, such that the two separately incident light beams are diffracted into a pair of co-propagating diffracted light beams.
In another embodiment disclosed herein, a method of multiplexing input light beams of differing wavelengths is provided. The method comprises providing a slab of material comprising opposed major surfaces, and receiving externally incident input light beams of differing wavelengths. The method further comprises diffracting two externally incident light beams at major surfaces of the slab into a superimposed pair of co-propagating diffracted light beams containing superimposed wavelength components of the two externally incident input light beams.
In yet another embodiment disclosed herein, a method of fabricating a slab optical multiplexer is provided. The method comprises providing a slab substrate of optically transmissive material, having flat and parallel opposing surfaces. The method further comprises forming micro-optical elements at the parallel surfaces, in which the micro-optical elements are selected from collimating/focusing elements and micro-diffractive optical elements.


A method to produce levulinic acid (LA) and γ-valerolactone (GVL) from biomass-derived cellulose by selective extraction of LA by alkylphenol (AP) and hydrogenation of LA, in which mineral acid used in the method is recycled and the final concentration of GVL is increased by successive extraction/hydrogenation steps to allow for effective separation by distillation.

Significant advances have been made in recent years with respect to using heterogeneous catalysts for converting biomass-derived compounds to fuels and chemicals. Conventional approaches deconstruct solid cellulose into smaller molecules that are soluble in various solvents (e.g., water, ionic liquids), thereby allowing transport of these reactants to the active sites on the heterogeneous catalyst, the majority of which are located within the pores of a high-surface area material. A difficulty in implementing this strategy is that chemical components used to deconstruct solid cellulose (e.g., sulfuric acid) may alter the performance of heterogeneous catalysts used subsequently to convert the soluble biomass-derived reactants to the desired fuels and/or chemicals. As a result, costly purification steps are required to implement a cascade catalytic process. Thus, the present method addresses a long-felt and unmet need by providing a route to levulinic acid and γ-valerolactone that uses an extraction solvent that does not entrain the strong acid used to deconstruct the reactant cellulose.

Method to produce and recover levulinic acid and/or gamma-valerolactone from aqueous solutions using alkylphenols


A Hall thruster includes an annular discharge region and an annular cathode concentric to the annular discharge region.

Ion accelerators with closed electron drift are also known as Hall-effect thrusters or Hall thrusters. Hall thrusters can be used on space vehicles for propulsion, station-keeping, orbit changes, or counteracting drag, for example. Hall thrusters generate thrust by supplying a propellant gas to an annular channel. The annular channel has a closed end with an anode and an open end through which the gas is discharged. A cathode introduces free electrons into the area of the open end. The electrons are induced to drift circumferentially in the annular channel by a generally radially extending magnetic field in combination with a longitudinal electric field, but the electrons eventually migrate to the anode. The electrons collide with the gas atoms to create ions. The longitudinal electric field accelerates the ions from the open end of the annular channel to generate a reaction force that produces thrust. In general, Hall thrusters come in wide range of discharge power configurations.


To increase capacity in a spread spectrum packet communication system, a closed loop power control (CLPC) is provided for a common/shared downlink transport channel, such as a Forward Access Channel (FACH) and Downlink Shared Channel (DSCH), by using an existing uplink Common Packet Channel (CPCH) mechanism. After an appropriate access phase and a collision detection phase, a mobile station sends its closed-loop power control information along with any packet data over the CPCH uplink channel. Concurrently, the base station (BS) begins its downlink transmission of data and control information to the mobile station (MS). The base station transmits the packet data through the common/shared downlink transport channel, and the power of that transmission is controlled in response to the control information sent by the MS. The power of the uplink transmission from the MS is controlled in response to the control information sent by the BS, for example via a dedicated downlink channel (DCH).

This invention relates to spread-spectrum communications, and more particularly to code-division-multiple-access (CDMA) cellular, packet-switched communication systems. The inventive concepts involve using a Common Packet Channel (CPCH) as an uplink transport channel to perform closed-loop power control of a common or shared downlink transport channel, such as the Forward Access Channel (FACH) or the Downlink Shared Channel (DSCH).
Recent developments in wireless communications technologies have allowed expansion of service offerings from the original voice telephone service model to include a number of services supporting packet data communications. As customers become increasingly familiar with data services offered through landline networks, they are increasingly demanding comparable data communications in the wireless domain, for example to maintain service while mobile subscribers roam freely or to provide remote service in locations where wireless loops are preferable to landline subscriber loops. A number of technologies support packet data communications in the wireless domain. Increasingly, these technologies rely on direct sequence spread spectrum communication over the air-link.
In a conventional Code Division Multiple Access (CDMA) communication system, information transmitted between stations is modulated using a spreading code. All stations transmit over one common frequency band. Different spreading codes are used to distinguish information associated with different stations. Logically speaking, the xe2x80x9cchannelsxe2x80x9d in such a communication system correspond to the different codes.
Since all stations transmit information using the common frequency band, the transmission from each station interferes with the communications of the other stations. In any such direct sequence spread spectrum communication system, when a particular device is attempting to receive a transmission, any transmissions of other stations using codes not recognized by or assigned to the particular device appear as background noise. If the noise level is too high at the receiver, that device can not accurately distinguish transmissions directed to it even though the signals were spread using the assigned code(s). For example, signals received by a base station from a mobile station close to the base station are much stronger than signals received from other mobile stations located at the base station""s cell boundary. As a result, distant mobile communications are overshadowed and dominated by closein mobile stations. This condition is sometimes referred as the xe2x80x9cnear-far effect.xe2x80x9d
To increase capacity it becomes necessary decrease interference. To that end, most conventional CDMA communication techniques involve some form of transmission power control. In a CDMA system, all mobile-transmitted signals should arrive at the base station with about the same average power irrespective of their distance from the base station. Typically, the mobile station attempts to control its transmit (uplink) power within a relatively small tolerance based on power control messages from the base station. Conventional dedicated channel communications in CDMA utilize a similar closed-loop power control for the downlink (or forward) transmit channel, except during hand-off wherein each base station varies the transmit power using an open-loop control algorithm.
These direct sequence spread spectrum communication techniques have been extensively developed and deployed to offer circuit switched communication services, particularly for voice telephone grade communications of mobile customers. These systems offer some limited data communications capabilities. However, customers increasingly are demanding higher-rate packet data communications in the wireless domain. Considerable technological effort is under way in the wireless industry to develop a third generation (3G) digital communication system, which among other services, will support higher-rate packet data communications.
Currently, there are two modes of operation for packet data transport in the 3GPP UMTS standard for wideband code division multiple access (W-CDMA), circuit mode and packet mode. A Dedicated Channel (DCH) is used to transfer packet data in a circuit mode of operation in both directions. In the packet mode, the Common Packet Channel (CPCH), the Forward Access Channel (FACH), and the Downlink Shared Channel (DSCH) offer a common packet data mechanism for bursty data Internet traffic, such as:
E-Commerce
Unified Messaging
Video Clips
Video Monitoring
Web Browsing
Chatting
Picture and File Transfers
As presently envisage for packet services, there are two or more xe2x80x9ccommon/shared downlink transport channels,xe2x80x9d of which the Forward Access Channel FACH is one and the Downlink Shared Channel (DSCH) is the other. In the current standards, the operation of the downlink common transport channels does not support closed loop power control (CLPC). In the case of DSCH, a pair of dedicated channels, one of which for the uplink and the other of which for the downlink, can be used to enable CLPC. However, this method is very inefficient and wastes valuable system capacity.
FIG. 1 shows an example of the current operation of a FACH type common downlink channel. As shown, the base station listens to a signaling message periodically sent by the mobile station indicating the level at which the mobile station can listen (lower line). Then, the base station transmits the packet through the FACH (top line). The base station can signal to the MS to initiate a downlink packet transfer through one of the available mechanisms, such as the FACH, the Broadcast Channel (BCH) or the Paging Indicator.
A basic common-packet channel (CPCH) provides an uplink transport channel for transmitting variable size packets from a mobile station (MS) to a base station (BS) without the need for direct resource allocation. The channel resource allocation is contention based. A number of mobile stations could at any time contend for the same resources, as found in ALOHA systems.
FIG. 2 shows the operation of a mobile station over a CPCH channel together with the related indicator channel and downlink channel from the base station. In operation, a mobile station (MS), having all the necessary information from a nearby BS, starts transmitting a series of access preambles as shown at AP in the lower line in FIG. 2. Each particular access preamble in the series is the same preamble, selected from a set of predefined access preambles corresponding to CPCH channels operating through the base station. The MS transmits each particular access preamble (AP) at predefined time intervals and at increasing power levels, preferably in a step-wise manner. The transmitted power during each access preamble transmission is constant.
When the base station receives and identifies one of the access preambles, it responds by transmitting a corresponding acknowledgment AP-ACK over the AP indicator channel (AP-AICH), as shown in the middle line in FIG. 2. With this ALOHA type access technique, there is a good possibility that two or more MSs may try to access the BS using the same access preamble at substantially the same time. In such a case, the AP-ACK acknowledgement signal could be successfully received by more than one MSs. If these MSs are allowed to transmit data, the transmissions will collide. In case of collision, none of the data from either of the transmitting MSs will be received correctly. To resolve this problem, the MSs need to undergo a collision detection or xe2x80x9cCDxe2x80x9d phase.
In the CD phase, upon receiving an AP-ACK acknowledgement, the MS randomly selects a collision detection (CD) signature from a predetermined set of possible CD signatures. The MS transmits a CD preamble containing the coded CD signature (shown as a CD packet in the lower line of FIG. 2). If the base station successfully receives a CD preamble, it sends back a CD acknowledgement (CD-ACK), which is the same as or otherwise corresponds to the CD signature transmitted by the MS, over a downlink indicator channel known as CD-ICH, as appears in the middle line in the drawing. The BS responds to only one of the many possible received CD preamble signatures transmitted by different MSs, to thereby allocate the CPCH channel to one of the contending mobile stations.
Upon receiving a CD-AICH corresponding to its own CD preamble signature, indicating that there are no collisions or the base station has resolved any collision, the MS will begin to send its closed-loop power control information along with its packet data. The BS will also begin to send any message data together with any closed-loop power control information over the downlink channel (top line in FIG. 2).
Data sent over the FACH (FIG. 1) can be transmitted only using a slow power control. Slow power control is equivalent to a downlink open loop power control. The power level at which the packet is transmitted constantly over the FACH is determined based on a signaling message periodically sent by the intended receiving mobile station (MS). As shown in FIG. 1, the base station transmits the message through the FACH at a constant level for the duration of the packet transmission, that is to say, at the continuous level indicated in the signaling message periodically sent by the mobile station. This type of power control is not very accurate and does not allow for any form of dynamic adjustment.
If a common downlink channel is used, such as FACH, there is no closed loop power control for the associated uplink channel because the common channel has no power control capability. Likewise, if a common uplink channel, such as a random access channel, (RACH) is used, then there will be no closed loop power control for the downlink channel. CLPC is possible only when the UL has control feature (e.g. using CPCH) and when the DL has control feature (e.g. DCH counterpart to FACH/DSCH).
As shown by the above discussion, these newer spread-spectrum techniques intended for wideband packet communication utilize CDMA spreading techniques, but so far have provided closed loop power control only for the dedicated channels and certain uplink common transport channels with predefined closed loop power control capabilities.
When a common or shared downlink packet channel does not support closed loop power control, the noise level and attendant interference over the air-link increases, which decreases the downlink capacity of the system. The downlink capacity becomes a significant quality of service issue for asymmetric communication services via the network, such as web browsing.
This invention introduces or enhances closed loop power control (CLPC) for common downlink transport channels, which addresses the above issue, thus improving the downlink capacity of these channels. The method provides an approach to resolve the lack or inefficiency of CLPC capability by using an existing uplink Common Packet Channel mechanism.
Hence, a general objective of the invention is to use a Common Packet Channel communication mechanism to enable closed loop power control for common or shared downlink transport channels, such as the forward access channel (FACH) and the downlink shared channel (DSCH).
Another objective relates to creating a bi-directional interactive or concurrent service by combining CPCH with the common/shared downlink transport channel.
The present invention provides an improvement to a code-division-multiple-access (CDMA) system employing spread-spectrum modulation. The present invention involves a closed loop power control (CLPC) for a common downlink transport channel, such as a Forward Access Channel (FACH), by using an existing uplink Common Packet Channel (CPCH) mechanism. Aspects of the invention encompass methods utilizing the CPCH mechanism for closed-loop power control of the common downlink transport channel, as well as base stations and mobiles stations and base-band processors for use in such stations, which implement the inventive closed-loop power control technique.
In a preferred embodiment, the CDMA system has a radio network controller (RNC) and a plurality of base stations, which serve a plurality of mobile or remote stations. Each base station (BS) has a BS-spread-spectrum transmitter and a BS-spread-spectrum receiver. Each mobile station (MS) has an MS-spread-spectrum transmitter and an MS-spread-spectrum receiver. In the preferred embodiment, the RNC monitors traffic demand, based on traffic measurement information of communications through the base stations for the mobile stations. Based on the traffic demand or a projection thereof, the RNC assigns channel resources to the base stations, by re-configuring the channel resources within each cell.
When a packet needs to be sent to a mobile station (MS), the RNC schedules the transmission at time t1 and controls the base station (BS) to broadcast, via a common broadcast channel, such scheduled transmission. At the recipient MS, upon receiving the broadcast, the steps preferably implement an access phase, a collision detection phase and a data transmission phase. There may also be a power control phase between the collision detection phase and the data transmission phase. As discussed more below, the data transmission phase provides closed loop power control.
The access phase includes starting transmission of a series of access preambles (AP) at well-selected time intervals and at increasing power levels. The MS stops its transmission of the AP when it successfully receives an acknowledgment AP-ACK, which indicates that the base station (BS) has picked up and detected one of the AP transmissions. Alternatively, the MS ceases its access preamble transmissions if the MS has transmitted the maximum allowed number of access preambles MAP.
Upon receiving this AP-ACK signal, each MS seeking access to the CPCH channel initiates the collision detection phase. Specifically, each such MS randomly selects one collision detection (CD) signature from a predefined signature set and transmits a CD preamble containing that signature. Since each mobile station randomly selects one of the possible collision detection (CD) signatures, typically, no two mobile stations seeking access to the same channel will pick the same CD signature. When the base station receives only one CD preamble, it assumes the CD preamble is sent by the intended recipient MS and proceeds to send a CD acknowledgment CD-ACK over the CD-ICH. The CD-ACK corresponds to the CD preamble signature from the MS. When the base station receives more than one CD preamble, it assumes at least one of the unintended recipients has mistaken itself as the intended recipient of the scheduled packet. Since the BS cannot identify the intended recipient based on the randomly selected CD signatures, it will refrain from responding to any of the CD preambles. The BS may repeat the process again from the beginning, until it has reached the maximum number of allowable tries.
Upon receiving a CD acknowledgement CD-ICH, which corresponds to the sent CD signature, the MS waits and begins to send its closed-loop power control along with any packet data at t1, t1 being the start of the data transmission phase. Concurrent with the transmission by the MS at t1, the base station (BS) begins its transmission to the MS. The base station transmission includes transmission of the packet data through a common downlink transport channel as well as transmission of the control information through a dedicated channel. The power of the BS transmission is controlled in response to the control information sent by the MS, and the power of the MS transmission is controlled in response to the control information sent by the BS. The closed-loop control of both air-link channels continues throughout the packet communication, to substantially continuously vary the power level of both the uplink and the downlink common transport channels.
Since the MS can send data along with its power control information, a bi-directional interactive transmission is created that incorporates two-way closed-loop power control. The MS ceases transmission immediately upon the release of the common downlink shared channel.

Closed loop power control for common downlink transport channels


A digital transmission system and method for coherent optical systems in which a source signal is frequency modulated by digital information and caused to be incident on a birefringent medium. Moudulation signals are produced having a polarization which is dependent on the frequency of the source signal. The information can be regenerated by processing only one of the modulation signals and thus only one need be transmitted. Further modulation signals may be transmitted to enable error checking at the receiver.

1. Field of the Invention
The invention relates to the transmission of digital information in which electro-magnetic radiation is modulated in accordance with the information.
2. Description of Related Art
Various detection methods have been proposed in the past for demodulating the transmitted radiation including coherent detection and direct detection. Although coherent detection has major advantages over direct detection, it has the drawback of polarization sensitivity. This problem could, in principle, be eliminated if a transmission medium could be developed which was polarization holding.
In the case of optical radiation, special optical fibres have been developed which are substantially polarization holding but these have complex structures and much higher losses (and are more expensive) when compared to standard circular symmetric monomode fibres. Furthermore, since large quantities of standard optical fibre have already been installed, are being installed, and are planned for the telecommunications which initially use polarization insensitive to direct detection, it is desirable to devise a transmission method and system which is compatible with these fibre coherent networks.
So far two schemes have been proposed that will enable coherent detection, to be used with standard fibre; these are active polarization control and polarization diversity. The former is capable of eliminating all polarization penalties. However, an extra opto-mechanical or electro-optic device is required in either the local oscillator or signal path at the receiver. This complicates the receiver and could also result in an insertion loss penalty. Polarization diversity reception eliminates the need for extra optical control devices in the receiver but requires the addition of a polarising beam splitter and a second photodiode, amplifier chain and intermediate frequency (I.F.) demodulator. With polarization diversity reception there can be up to 3 dB receiver sensitivity penalty for certain combinations of input polarization and local oscillator polarization states when the outputs of the two I.F. demodulators are simply combined (although it may be possible to reduce this penalty to about 1 dB with more complex post demodulator processing).
These two methods of overcoming polarization problems both result in a more complex receiver which although possibly acceptable in a long distance high capacity point-to-point transmission link could introduce a significant cost penalty in a local wideband distribution scheme or LAN/MAN type application.

Polarization modulation of optical signals using birefringent medium

British Telecommunications public limited company


Ligomeric sulfonic acid derivatives having repeating units of the formula I ##STR1## in which R.sup.1 is an alkyl, haloalkyl or aryl radical,. R.sup.2 is a hydrogen atom, an alkyl, alkenyl or aryl radical or the group (R.sup.1 --SO.sub.2 --O--).sub.n X--, PA1 R.sup.3 is a cycloalkylenedialkyl, cycloalkenylenedialkyl, arylenedialkyl, heteroarylenedialkyl group, alkylene, alkenylene, alkynylene, cycloalkylene or arylene group, PA1 X is an alkylene, cycloalkylene or arylene group Y is O, S, CO, CO--O, SO.sub.2, SO.sub.2 --O, NR.sup.4, CO--NH, O--CO--NR.sup.5, NH--CO--NR.sup.5 or NR.sup.5 --CO--O, PA1 Z is O, CO--NR.sup.6, O--CO--NR.sup.6 or NH--CO--NR.sup.6, PA1 R.sup.4 is an acyl radical, PA1 R.sup.5 is a hydrogen atom or an alkyl-, cycloalkyl, alkenyl, alkynyl or aryl radical, PA1 R.sup.6 is an alkyl, cycloalkyl, alkenyl, alkynyl or aryl radical, PA1 k is 0, 1, 2, 3 or 4, PA1 m is an integer greater than 1 and PA1 n is 1, 2 or 3,. generate sulfonic acids under irradiation and are cleavable by the latter. In combination with alkali-soluble binders, they give positive-working mixtures which are used especially in recording materials for UV radiation and high-energy radiation. The recording materials are distinguished by a high resolution in conjunction with high image contrast and excellent storage stability.

1. Field of the Invention
The invention relates to radiation-sensitive and acid-cleavable compounds and to a radiation-sensitive mixture which is positive-working, i.e., which becomes soluble as a result of irradiation, which contains these compounds. The mixture contains
(a) a binder which is insoluble in water and soluble or at least swellable in aqueous alkaline solutions, and PA1 (b) an oligomeric compound which generates a strong acid under the action of actinic radiation and which has at least one acid-clearable C--O--C bond. PA1 R.sup.2 is a hydrogen atom, an alkyl, alkenyl or aryl radical or the group (R.sup.1 --SO.sub.2 --O--).sub.n X--, PA1 R.sup.3 is a cycloalkylenedialkyl, cycloalkenylenedialkyl, arylenedialkyl, heteroarylenedialkyl, alkylene, alkenylene, alkynylene, cycloalkylene or arylene group, PA1 X is an alkylene, cycloalkylene or arylene group if n is 1, or a (n+1)--valent radical of an alkene, cycloalkene, or arene if n is 2 or 3. PA1 Y is O, S, CO, CO--O, SO.sub.2, SO.sub.2 --O, NR.sup.4, CO--NH, O--CO--NR.sup.5, NH--CO--NR.sup.5 or NR.sup.5 --CO--O, PA1 Z is O, CO--NR.sup.6, O--CO--NR.sup.6 or NH--CO--NR.sup.6, PA1 R.sup.4 is an acyl radical, PA1 R.sup.5 is a hydrogen atom or an alkyl, cycloalkyl, alkenyl, alkynyl or aryl radical, PA1 R.sup.6 is an alkyl, cycloalkyl, alkenyl, alkynyl or aryl radical, PA1 k is an integer from 0, 1, 2, 3 or 4, PA1 m is an integer greater than 1 and n is an integer from 1, 2 or 3,
The invention also relates to a radiation-sensitive recording material produced from this mixture which is suitable for producing photoresists, electronic components, printing plates or for chemical milling.
2. Description of Related Art
The continuing reduction in the size of the structures, for example, in chip manufacture down into the range of less than 1 .mu.m, requires modified lithographic techniques. To form images of such fine structures, radiation of a short wavelength is used, such as high-energy LrV light, electron beams and X-rays. The radiation-sensitive mixture must be adapted to the short-wave radiation. A compilation of the requirements to be met by the radiation-sensitive mixture is given in the article by C. G. Willson "Organic Resist Materials--Theory and Chemistry" [Introduction to Microlithography, Theory, Materials, and Processing, editors L. F. Thompson, C. G. Willson, M. J. Bowden, ACS Symp. Ser., 219, 87 (1983), American Chemical Society, Washington].
There is therefore an increased demand for radiation-sensitive mixtures which can be used in the more recent technologies, such as mid-UV or deep-UV lithography [exposure, for example, with excimer lasers at wave-lengths of 305 nm (XeF), 248 nm (KrF), 193 nm (ArF)], electron beam lithography or X-ray lithography, and which, furthermore, are preferably sensitive in a wide spectral range and correspondingly can also be used in conventional UV lithography.
Positive-working radiation-sensitive mixtures for producing radiation-sensitive recording materials are known. Mixtures which contain o-quinone--diazide derivatives in binders soluble in aqueous alkaline media, for example novolaks or polyhydroxystyrenes, are commercially available. However, the sensitivity of these materials to actinic radiation, and especially high-energy short-wave radiation, such as light from a KrF-excimer laser having a wavelength of 248 nm or electron beams, is inadequate.
Positive-working radiation-sensitive mixtures are also known in which an acid is generated by the action of actinic radiation on a photoinitiator contained in this mixture and this acid then, in a subsequent reaction, renders an acid-cleavable compound likewise contained in the mixture soluble in the irradiated areas under the action of an appropriate, preferably aqueous alkaline developer. Such materials are in general distinguished by an enhanced sensitivity to actinic radiation.
Numerous mixtures are known which contain, as the essential components, a polymeric binder soluble in aqueous alkaline solutions, a solubility-inhibiting compound and a compound which, on irradiation, generates the acid required for cleavage. The binder is in most cases a novolak resin. Many of these mixtures have a high sensitivity to actinic radiation. They are designated as chemically amplified, photocatalytic 3-component systems.
Of these mixtures, those whose acid-clearable component contains one or more acetal units have gained commercial importance. These mixtures have, however, certain disadvantages. They possess only a limited stability on the substrate materials to which they have to be applied, which leads to an unsatisfactory, not reducible reproduction of the image original. This can be improved only by introducing additional protective layers, for example according to DE-A 3,621,376, equivalent to U.S. Pat. No. 4,840,867. The causes of the deterioration in the image reproduction are not fully known and have not been adequately investigated. For example, the process window, i.e., the processing latitude, for the exposure of these mixtures is very narrow and frequently not unambiguously reproducible. In particular, the quality of the image reproduction greatly depends on the time difference between exposure and development, the so-called delay time. In principle, it must be assumed that diffusion processes which cause this behavior are not easily controllable. In addition, however, it may be presumed that, during drying of the mixture on a substrate material, partial vaporization of the photoinitiator or of the acid-unstable compound or segregation of the individual mixture constituents takes place, which is observed with particular frequency in the case of acid-unstable compounds having a low solubility in the usual coating solvents.
It is also known from the papers by C. C. Petropoulos [J. Polym. Sci., Polym. Chem. Ed., 15, 1637 (1977)] that aromatic acetals which carry a nitro group in the vicinal position, are photodecomposable by high-energy UV radiation without acid catalysis, and can be used in positive-working radiation-sensitive recording materials. The photosensitivity of these compounds is likewise inadequate for applications in practice, since their photoreaction cannot be chemically amplified.
In DE-A 3,721,741, equivalent to U.S. Pat. No. 4,883,740, radiation-sensitive mixtures are described which contain a polymeric binder insoluble in water and soluble in aqueous alkaline solutions, and an organic compound which contains at least one acid-cleavable grouping and a grouping which generates a strong acid under the action of radiation. The radiation-sensitive groups described are exclusively onium salt groups, in particular sulfonium salt groups.
The use of onium salts, such as diazonium, phosphonium, sulfonium and iodonium salts, of nonnucleophilic acids such as HSbF.sub.6, HAsF.sub.6 or HPF.sub.6 as photolytic acid generators involves disadvantages which drastically restrict their possible uses in various fields of application. For example, many of the onium salts are toxic. Their solubility is inadequate in many solvents, which is why only a few solvents are suitable for preparing a coating solution. Furthermore, when the onium salts are used, undesired foreign atoms are sometimes introduced which can cause interference with the process, especially in microlithography. Moreover, the onium salts form Bronstedt acids, which have a very severe corrosive action, in the photolysis. These acids attack sensitive substrates, so that the use of such mixtures leads to unsatisfactory results. Halogen compounds such as trichloromethyltriazine derivatives or trichloromethyloxadiazole derivatives also form hydrohalic acids which have a severely corrosive action.
In more recent papers by F. M. Houlihan et al., SPIE 920, 67 (1988), it was shown by reference to positive-working systems that, in addition to the above-mentioned acid generators, nitrobenzyl tosylates, which on exposure generate sulfonic acids having a low migration tendency, can be used in certain acid-unstable resist formulations. It can be deduced from these results that such compounds can also be used for photo-curable systems. However, the sensitivities thus achieved, especially to UV radiation from 350 to 450 nm, and the thermal stability of the photoresists have proven to be inadequate.
Because of the inadequacies and disadvantages described above, there is a demand for radiation-sensitive mixtures which do not have these disadvantages and possess a reactivity suitable in practice.

Acid-cleavable radiation-sensitive compounds, radiation-sensitive mixture containing these compounds, and radiation-sensitive recording material produced with this mixture


Structure and methods of determining the complete location of a buried short using voltage contrast inspection are disclosed. In one embodiment, a method includes providing a test structure having a PN junction thereunder; and using the PN junction to determine the location of the buried short using voltage contrast (VC) inspection. A test structure may include a plurality of test elements each having a PN junction thereunder, wherein a location of the buried short within the test structure can be determined using the PN junction and the VC inspection. The PN junction forces a change in illumination brightness of a test element including the buried short, thus allowing determination of the complete location of a buried short.

1. Technical Field
The invention relates generally to semiconductor fabrication, and more particularly, to test structures and a method of determining the complete location of a buried short using voltage contrast inspection.
2. Background Art
In-line voltage contrast (VC) inspection is a powerful technique for detecting and isolating yield limiting defects in the semiconductor fabricating industry. In-line VC inspection includes scanning the wafer surface in which test structures exist with a scanning electron microscope (SEM). As the inspection proceeds, the SEM induces charge on all electrically floating elements whereas any grounded elements remain at zero potential. This potential difference is visible to the SEM. In particular, for electron landing energies less than the second crossover of the secondary electron yield curve (approximately 1.5 keV for tungsten (W) and copper (Cu)), grounded elements appear bright whereas floating elements appear dark.
Test structures exploiting this phenomenon can be created for many yield limiting defects including metal, gate and active region shorts and opens, and via and contact opens. For example, FIGS. 1A-B, show a short (FIG. 1B) indicated by a normally floating (dark) element becoming bright, and an open (FIG. 1A) indicated when a normally bright element becomes dark.
One advantage of this technique is that even if the defect causing the electrical failure is buried or extremely small, its existence is flagged by a change in the VC inspection signal of the entire element. Referring to FIG. 2, as a result of this situation it is possible to scan (between dashed lines) just the bottom of a test structure 10 and still detect the existence of an electrically active defect 12, 14 anywhere on that structure. See, for example, Weiner, K., Henry T., Satya, A., Verman, G., Wu, R., Patterson, O., Crevasse, B., Cauffman, K., Cauffman, W., Defect Management for 300 mm and 130 mm Technologies Part 3: Another Day, Another Yield Learning Cycle, Yield Management Solutions magazine, Vol. 4, Iss. 1, pp. 15-27, Winter 2002. This technique is referred to as "area acceleration" because only a small portion of an area (between dashed lines) must be scanned during VC inspection in order to identify a defect. FIG. 2 shows how the VC inspection pattern changes when a short 12 or open 14 exists. Test structure 10 includes a grounded comb 16 including grounded tines 18 which are interleaved with ungrounded tines 20 of a second backless comb 22. Ungrounded tines 22 are isolated from each other and grounded comb 16. If an open 14 exists on a grounded tine 180 of grounded comb 16, the VC signal changes on that tine 180, e.g., it is darker in parts than other grounded tines 18 on the open portion. If a short 12 exists between a grounded tine 18 and a floating, ungrounded tine 20S of backless comb 22, the VC signal of the floating tine changes, e.g., the shorted ungrounded tine 20S illuminates brighter than other ungrounded tines 20.
KLA-Tencor markets a product called uLoop™ that is based on the above-described principal. Using this technology, once a defect is detected using a scan as shown in FIG. 2 (between dashed lines) in a first (x) direction, the x coordinate of the defect is established. Next, the structure can be scanned in a second (y) direction for the location of the buried short to be determined. The uLoop™ software does this automatically. It also can be done manually fairly easily, although not nearly as quickly, using an inspection SEM, a review or critical dimension (CD) SEM or a focused ion beam (FIB) tool. In any case, only a small fraction of the test structure needs to be scanned. Applying area acceleration typically results in a time savings of 70-90%.
Unfortunately, in some cases a defect is not visible. For example, oftentimes contact or via opens, buried metal shorts, gate oxide shorts or silicide pipes are not visible. Such defects are often referred to as buried shorts. The location of buried opens, and in particular their y coordinate, on area accelerated test structures can be determined because the VC signal will change at the location of the defect as shown in FIG. 2 for tine 180, and as shown in the images of FIGS. 1A and 1C. The location cannot, however, be established for buried shorts because the illumination brightness of the tine containing the short will be the same regardless of the short's location. For example, shorted tine 20S in FIG. 2 illuminates the same along it's entire length. FIG. 1B also shows this situation.
One approach for isolating a buried short using VC inspection is to divide the test structure design into small pieces for analysis. FIG. 3 shows how test structure 10 in FIG. 2 may be modified so that a buried short could be isolated. FIG. 4 shows such a test structure 30 that could be used to detect silicide pipes, with polysilicon conductor regions 31 and source and drain regions 33. Unfortunately, area accelerated VC inspection cannot be applied to these structures. That is, the entire structure must be VC inspected. In another approach, an area accelerated test structure is used like test structure 10 in FIG. 2, and the defect is located using an in-line FIB tool. This approach requires that the defective tine be cut in half. The half with the VC signal would then be split again and so forth. A buried short on a 1 mm long tine could be isolated to a 1 μm segment using 10 cuts. Unfortunately, this approach is expensive and time consuming and results in wafer scrap.
In view of the foregoing, there is a need in the art for a solution to the problems of the related art.

Buried short location determination using voltage contrast inspection

International Business Machines Corporation


Preparing a stencil mask comprising a silicon thin film in which an opening for selectively irradiating charged particles to a semiconductor substrate is provided and whose irradiation surface on which the charged particles are irradiated is implanted with an impurity, and selectively irradiating charged particles to the semiconductor substrate using the stencil mask which is opposingly arranged on the semiconductor substrate.

This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 2000-333914, filed Oct. 31, 2000; and No. 2001-290118, filed Sep. 21, 2001, the entire contents of both of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to method for manufacturing a semiconductor device using a stencil mask, a stencil mask used the method for manufacturing a semiconductor device, and method for manufacturing the stencil mask.
2. Description of the Related Art
There is a method in which a stencil mask (or an aperture) having an opening is set at a certain distance on a substrate and an ion implantation is carried out, in a manufacturing process of a semiconductor device, in a process where a MOSFET in which its electrically conductive types of a channel within the same substrate are different or a MOSFET in which its threshold voltages are different is manufactured, when an ion implantation of an impurity is carried out into a well, a channel or Poly-Si.
In the case where a stencil mask is used in the ion implantation process in the manufacturing for a semiconductor device, it is carried out by employing a stencil mask having an opening limited to a region for ion implantation of the object of a substrate to be processed. Specifically, in the desired ion implantation region, ions are implanted through the opening of a stencil mask, and in a region for non-ion implantation, ions are shielded by a stencil mask shielding portion. However, on the stencil mask for shielding an ion, shielded ions are accumulated by repetitive ion implantations. Damages are also accumulated by shielded ions repeatedly crushing. As a result, after a plurality of ion implantation processes, the stencil mask is deformed and the ion implantation cannot be carried out with a high precision for positions.
For example, as shown in FIG. 39, when an impurity ion 4204 is implanted into a Si substrate 4201 on which an isolation region 4202 is formed through the opening of a stencil mask 4203 interspatially installed, if a distortion is generated on the stencil mask 4203, since the position of the opening is displaced, an ion implantation region 4205 is not formed over the whole desired region, and a non-ion implantation region 4206 is formed. Moreover, depending on the shape of rough coating pattern, a problem is occurred that an n-type impurity is implanted over to a region in which a p-type region is to be formed.
As a result, the electric characteristics of a manufactured semiconductor product are varied, or the product poorly operates. Therefore, a stencil mask becomes unusable after it is used in the process of a plurality of ion implantations. The cost of manufacturing a stencil mask is converted to the cost of a manufacturing a semiconductor device, it leads to the rise of the manufacturing cost of the semiconductor device.
Moreover, in the case of a stencil mask employing a SOI substrate, since it is shielded by a thin film portion region having an opening and a supporting portion for supporting the thin film portion region in which the oxide film is an insulating film, its electrical conductivity and thermal conductivity are poor, and when it is used in the manufacturing process of a semiconductor, there has been a problem that the deformation due to the heat occurs or the ability of pattern formation is lowered due to the accumulation of charges.
By the way, in the manufacturing for a semiconductor device employing charged particles represented by ion implantation process, it is required that the desired particles uniformly reach to the region of the object. Therefore, it is needed that the uniformity is confirmed, that is, the amount of particles is measured by spatial separation, and when it does not have the desired uniformity, the uniformity should be maintained by performing the adjustment of the particle generation source within the apparatus for manufacturing a semiconductor device and the transport system of the particles on the basis of the measured signal. Moreover, in order to maintain the uniformity of the processing state among a plurality of processing substrates, it is required that the amount of particles reaching to the processing substrate is finely and precisely measured.
For the confirmation of this uniformity and the definition of the number of the particles reached to the substrate, there is a method of confirming the state of the substrate to be processed using another measurement device by actually performing the processing to the substrate to be processed. However, in this case, since the time is taken from the processing to the measurement, it is difficult to readjust the device on the basis of the result.
Therefore, it is desirable that the measurement for the uniformity is performed within the device, the re-adjustment of the device is performed on the basis of the measurement of the results and the uniformity is measured again. For the measurement of the uniformity within the device, there is a method of evaluating the uniformity by measuring the output from the probes, for example, such as Faraday gauges or the like arranged in lines for measuring the electric charge amount of the particles passing through the specific region.
However, since these probes measure the valence electrons, any information concerning with the neutralized particles cannot be obtained. On the other hand, for example, in the ion implantation process, an ion may be neutralized due to the influence of the residual gas in the device, and the neutralized particles also act similarly as the ion does to the substrate to be processed. Therefore, a probe capable of measuring particles including the neutral particles has been required. Moreover, it has been desired that the spatial resolution is enhanced upon the measurement along with the miniaturization and refinement of a semiconductor element, however, it has been difficult to miniaturize a probe for it.
As described above, it has been desired that in-plane distribution of the number of the neutral particles and the charged particles reached to the semiconductor substrate is measured and the number of particles reached to the semiconductor substrate is precisely controlled.
As described above, in the case where a stencil mask is used in the ion implantation process a plurality of times, the distortion of the mask is generated, and the ion implantation position with respect to the semiconductor substrate is deviated, thereby making the electric characteristics of the semiconductor products to be varied or making the product poorly operate. Therefore, in order to lower the manufacturing cost of the semiconductor device, a stencil mask capable of being made in a cheap cost or a stencil mask having a long life has been desired.
Moreover, there has been a problem that an ability of pattern formation is lowered due to the deformation with heat and the accumulation of electric charges caused by electrification.
A device for measurement capable of measuring an in-plane distribution of the number of the neutral particles and the charged particles reached to the substrate has been required.
The present invention is configured so as to achieve the above-described objects as the followings.
(1) According to one aspect of the present invention, there is provided a method for manufacturing a semiconductor device comprising: a method for manufacturing a semiconductor device comprising: preparing a stencil mask comprising a silicon thin film in which an opening for selectively irradiating charged particles to a semiconductor substrate is provided and whose irradiation surface on which the charged particles are irradiated is implanted with an impurity; and selectively irradiating charged particles to the semiconductor substrate using the stencil mask which is opposingly arranged on the semiconductor substrate.
(2) According to one aspect of the present invention, there is provided a method for manufacturing a semiconductor device comprising: preparing a stencil mask comprising a metal thin film in which an opening for selectively irradiating charged particles to a semiconductor substrate is formed and a semiconductor layer formed on an irradiation surface of the metal thin film on which the charged particles are irradiated; and selectively irradiating charged particles to a semiconductor substrate using the stencil mask which is opposingly arranged on the semiconductor substrate.
(3) According to one aspect of the present invention, there is provided a method for manufacturing a semiconductor device comprising: preparing a stencil mask comprising a thin film in which an opening for selectively irradiating charged particles to a semiconductor substrate is formed and a plurality of covering layers formed on a surface of the thin film; and selectively irradiating charged particles to a semiconductor substrate using the stencil mask which is opposingly arranged on the semiconductor substrate.
(4) According to one aspect of the present invention, there is provided a method for manufacturing a semiconductor device comprising: preparing a stencil a mask comprising a silicon thin film in which an opening for selectively irradiating charged particles to a semiconductor substrate is formed and an insulating layer formed on an irradiation surface of the silicon thin film on which the charged particles are irradiated; and selectively irradiating charged particles to a semiconductor substrate using the stencil mask which is opposingly arranged on the semiconductor substrate.
(5) According to one aspect of the present invention, there is provided a method for manufacturing a semiconductor device comprising: preparing a stencil mask comprising a shielding film in which an opening for selectively irradiating charged particles to a semiconductor substrate is formed and an resist film formed on an irradiation surface of the shielding film on which the charged particles are irradiated; and selectively irradiating charged particles to a semiconductor substrate using the stencil mask which is opposingly arranged on the semiconductor substrate.
(6) According to one aspect of the present invention, there is provided a method for manufacturing a semiconductor device comprising: selectively forming a first resist film on an irradiation surface of the shielding film on which charged particles are irradiated to a stencil mask having the shielding film in which an opening through which charged particles pass is provided; selectively irradiating charged particles to one or more sheets of semiconductor substrates using the stencil mask comprising the first resist film; removing a resist formed on an irradiation surface of the stencil mask; selectively forming a second resist film on an irradiation surface of the shielding film on which the charged particles are irradiated; and selectively irradiating charged particles to the semiconductor substrate once or more.
(7) According to one aspect of the present invention, there is provided a method for manufacturing a semiconductor device comprising: preparing a stencil mask comprising a thin film provided with an opening for selectively irradiating charged particles to a semiconductor substrate, depth of the opening being different corresponding to the size of the opening; and selectively irradiating charged particles to a semiconductor substrate using the stencil mask which is opposingly arranged on the semiconductor substrate.
(8) According to one aspect of the present invention, there is provided a method for manufacturing a semiconductor device comprising: preparing a stencil mask comprising a thin film in which an opening for selectively irradiating charged particles to a semiconductor substrate is provided, an insulating layer which is formed on an irradiation surface of the thin film on which the charged particles are irradiated and a supporting substrate which is formed on the thin film and the insulating layer and which is conductive to the thin film; selectively irradiating charged particles to the semiconductor substrate using the stencil mask which is opposingly arranged on a semiconductor substrate; and discharging the charged particles attached to the thin film from the stencil mask via the supporting substrate by irradiation of the charged particles.
(9) According to one aspect of the present invention, there is provided a method for manufacturing a semiconductor device comprising: selectively implanting ions to a semiconductor substrate by irradiating charged particles to the semiconductor substrate via a stencil mask comprising a thin film opposingly arranged on the semiconductor substrate and having an opening; and adjusting a potential difference between the thin film and the semiconductor substrate during irradiation of the charged particles.
(10) According to one aspect of the present invention, there is provided a method for manufacturing a semiconductor device in which particle beam including ions and neutral particles of impurity are irradiated to a semiconductor substrate installed at an irradiation position and an impurity of implantation amount D per unit area is implanted to the semiconductor substrate, the method comprising: irradiating the particle beam to a particle amount measurement device comprising an electron generation/discharging device which is installed nearby the irradiation position in a state where the semiconductor substrate is not irradiated by the particle beam and which generates and amplifies electrons corresponding to an incident position of ions and neutral particles incident to a measurement surface and discharges the electrons from back surface side, an electron detector for measuring a position and an amount of electrons discharged from the electron generation/discharging device, and a particle amount calculation section for calculating a distribution of total particle amount of ions and neutral particles incident to a surface of the particle detector from positions and amount of electrons measured by the electron detector and irradiating the particle beam and to a beam current measurement device installed at a position different from the irradiation position for measuring current by the ions; measuring an in-plane distribution of a total particle amount of the ions and neutral particles of particle beam irradiated to the electron generation/discharging device using the particle amount measurement device; controlling an in-plane distribution of a total particle amount by adjusting a generating system for generating the particle beam and a transporting system through which the generated particle beam pass; moving the semiconductor substrate to the irradiation position; and irradiating the particle beam to the semiconductor substrate.
(11) According to one aspect of the present invention, there is provided a method for manufacturing a semiconductor device in which particle beam including ions and neutral particles of impurity are irradiated to a semiconductor substrate installed at an irradiation position and an impurity of implantation amount D per unit area is implanted to the semiconductor substrate, the method comprising: irradiating the particle beam to a particle amount measurement device comprising an electron generation/discharging device which is installed nearby the irradiation position in a state where the semiconductor substrate is not irradiated by particle beam and which generates and amplifies electrons corresponding to an incident position of ions and neutral particles incident to a measurement surface and discharges the electrons from back surface side, an electron detector for measuring a position and an amount of electrons discharged from the electron generation/discharging device, and a particle amount calculation section for calculating a distribution of total particle amount of ions and neutral particles incident to a surface of the particle detector from positions and amount of electrons measured by the electron detector and irradiating the particle beam and to a beam current measurement device installed at a position different from the irradiation position for measuring current by the ions; finding an ion amount N2 per unit area incident to the beam current measurement device from a current measured by the beam current measurement device as well as measuring total amount of particles N of ions and neutral particles incident to unit area of the measurement surface by the particle amount measurement device; finding conversion value D2=Dxc3x97(N2/N) from the total amount of particles N, the amount of ions N2 and the amount of impurity D; installing the semiconductor substrate to the irradiation position; irradiating particle beam to the semiconductor substrate to implanted an impurity into the semiconductor substrate; measuring a current due to the ions by the beam current measurement device during implantation of the impurity and finding the amount of ions N2xe2x80x2 from measured current; and terminating the implantation of the impurity when the amount of ions N2xe2x80x2 and the conversion value D2 become equal to each other.
(12) According to one aspect of the present invention, there is provided a stencil mask comprising a silicon thin film in which an opening is formed, wherein an impurity is implanted into a surface of the silicon thin film.
(13) According to one aspect of the present invention, there is provided a stencil mask comprising: a metal thin film in which an opening is formed; a semiconductor layer formed on a surface of the metal thin film.
(14) According to one aspect of the present invention, there is provided a stencil mask comprising: a thin film in which an opening is formed; and a plurality of covering layers formed on a surface of the thin film.
(15) According to one aspect of the present invention, there is provided a stencil mask which used for an ion implantation process using a silicon thin film in which an opening is formed, wherein an insulating layer is formed on a surface of the silicon thin film.
(16) According to one aspect of the present invention, there is provided a stencil mask comprising: a thin film in which an opening through which charged particles pass is provided; and a resist film formed on an irradiation surface of the thin film on which the charged particles are irradiated.
(17) According to one aspect of the present invention, there is provided a stencil mask comprising: a thin film in which an opening through which charged particles pass is provided, the depth of the opening being different corresponding to the size of the opening.
(18) According to one aspect of the present invention, there is provided a stencil mask comprising: a thin film in which an opening for selectively irradiating charged particles to a substrate to be processed; an insulating layer formed on an irradiation surface of the thin film on which the charged particles are irradiated; and a supporting substrate formed on the thin film and the insulating layer and conductive to the thin film.
(19) According to one aspect of the present invention, there is provided a method for manufacturing a stencil mask, comprising: implanting an impurity into a surface side of a silicon thin film in which an opening is formed; and heating the silicon thin film.
(20) According to one aspect of the present invention, there is provided a method for manufacturing a stencil mask comprising: implanting an impurity into a silicon thin film surface of a SOI substrate in which a supporting substrate, an insulating layer and a silicon thin layer are stacked; patterning the silicon thin film and forming an opening through which the insulating layer is exposed on a bottom of the silicon thin film; and removing one portion of the supporting substrate and the insulating layer and exposing a bottom surface of an opening.
(21) According to one aspect of the present invention, there is provided a method for manufacturing a stencil mask comprising: implanting an impurity into one surface of a silicon substrate; heating the silicon substrate; joining a surface to which an impurity is implanted and an insulating layer formed on a supporting substrate; grinding the silicon substrate to form a silicon thin film; patterning the silicon thin film and forming an opening through which the insulating layer is exposed; implanting an impurity to a surface of the silicon thin film; heating the silicon thin film; and removing one portion of the supporting substrate and the insulating layer and exposing a bottom surface of the opening.

Method for manufacturing a semiconductor device, stencil mask and method for manufacturing the same


The invention provides a microwave oven having an integral mixing assembly for agitating food inside of the microwave chamber during cooking. The mixing assembly includes a mixer shaft which is received through the top microwave chamber wall and which is capable of rotational movement. The mixer shaft is powered for rotational movement by a motor. The end of the mixer shaft disposed inside of the microwave chamber is adapted for releasable connection to one or more stirring or agitating means. A belt drive system and support mechanism are provided to control rotation of the mixer shaft.

Microwave cooking is popular as a quick and convenient way of preparing many types of foods. One important characteristic of microwave cooking is that the food cooks from the outside to the inside. It is therefore known that microwave cooking can cook food unevenly such that the center cooks less than the peripheral areas. This may be an advantageous feature in the preparation of certain food products such as meat where it may be desired to serve the product less well done. In addition, the uneven cooking characteristic of microwave ovens has not been a major drawback in the heating of pre-cooked food products, due to differing food densities.
However, the uneven cooking associated with microwave ovens has posed a major problem in the cooking of food products which have not been pre-cooked, such as eggs and sauces. In such instances, the even distribution of heat throughout the food product is crucial to complete and thorough cooking. Uniform cooking is particularly important in the preparation of foods which ordinarily require mixing such as batters, doughs, sauces, stews and the like. Heretofore, microwave cooking has not been particularly suitable for the preparation of such foods which require mixing and a substantially even distribution of heat. At present, the microwave cooking process must be stopped and the oven must be opened so that the food can be stirred. Thus, there is a need for a microwave oven which permits all cooking and stirring operations that might be done on a stove top to be accomplished therein.
Accordingly, it is an object of the invention to provide a microwave mixer which ensures that liquid, semi-liquid and mixable foods are uniformly and completely cooked by mixing the same during the cooking process.
It is a further object of the invention to provide a microwave oven having an integral mixing means for mixing food in the microwave chamber during cooking.

Microwave oven having integral mixing assembly


The present invention relates to a non-human transgenic animal, particularly a knock in mouse, whose genome comprises a heterologous, chimeric CTLA4 gene. The chimeric CTLA4 gene comprises exon 2 of the human CTLA4 gene, exon 1 and exon 4 of the non-human animal, and exon 3 of the CTLA4 gene of the non-human animal, or preferably, exon 3 of the human CTLA4 gene. The invention also relates to methods by which the transgenic mice are used to screen for monoclonal antibodies or other molecules that enhance immunity to tumors and infectious agents by interacting with the human CTLA4 receptor. The transgenic mice of the present invention are also useful for screening for monoclonal antibodies or other molecules that inhibit autoimmunity and transplant rejection.

Two types of signals are required for T cell activation and proliferation. The first gives specificity to the immune response and involves an interaction between the T-cell receptor/CD3 complex and an antigenic peptide presented by major histocompatibility complex (MHC) class I or class II proteins on the surface of an antigen-presenting cell (APC). The second, called a costimulatory signal, involves interaction between receptor-ligand pairs expressed on the surface of APCs and T cells. Antigenic stimulation in the absence of costimulation induces a state of unresponsiveness or anergy and eventual cell death by apoptosis in the responding T cells. Thus, antigenic stimulation in the presence of costimulation prevents anergy and cell death, thereby promoting cell survival.
A number of investigators have demonstrated that expression of the costimulatory ligands B7-1 and B7-2 on tumor cells can significantly increase immunogenicity of tumors, and induce tumor rejection by a T cell-dependent mechanism. (Baskar, S., Ostrand-Rosenberg, S., Nabavi, N., and Glimcher, L. (1993). Proc. Natl. Acad. Sci. USA. 90, 7015-7019; Chen, L., Ashe, S., Brady, W. A., Hellstrom, I., Hellstrom, K. E., Ledbetter, J. A., McGowan, P., and Linsley, P. S. (1992) Cell 71, 1093-102; Ramarathinam, L., Castle, M., Wu, Y., and Liu, Y. (1994). J Exp Med 179, 1205-14; Townsend, S. E., and Allison, J. P. (1993) Science 259, 368-370). CD28 and CTL4A are two T cell receptors that bind to the B7-1 and B7-2 ligands. CD28 is a transmembrane homodimer that is constitutively expressed on 90% of mammalian CD4+T cells. Engagement of CD28 by its ligands B7-1 or B7-2 on the surface of APCs initiates a signaling cascade culminating in cytokine production and expansion of specific T-cells. CTLA-4, a structural homologue of CD28, is a transmembrane protein that is expressed on activated T cells. The role of B7-CTLA4 interaction remains controversial. (Liu, Y. (1997). Immunol Today 18, 569-72).
Anti-CTLA4 Antibodies
Allison and colleagues have demonstrated that anti-mouse CTLA4 mAb induced rejection of tumors in vivo (Leach et al., 1996) Anti-CTLA4 mAb-treatment has also been shown to enhance immune response of mouse to bacteria. (Heinzel, F. P., and Maier, R. A., Jr. (1999). Infect Immun 67, 6454-60; Kirman, J., McCoy, K., Hook, S., Prout, M., Delahunt, B., Orme, I., Frank, A., and Le Gros, G. (1999). Infect Immun 67, 3786-92).
CTLA4 has also been shown to play an important role in autoimmune diseases. Numerous studies have linked the polymorphism of the CTLA4 gene in humans to a variety of autoimmune diseases, such as Graves' disease, Hashimoto's thyroiditis, myasthenia gravis with thymoma, and insulin-dependent diabetes mellitus. (Barbesino et al., 1998; Braun et al., 1998; Donner et al., 1997; Donner et al., 1997; Huang et al., 2000; Huang et al., 1998; Kotsa et al., 1997; Marron et al., 1997; Nistico et al., 1996; Tomer et al., 1997). In addition, treatment with anti-CTLA4 mAbs has been shown to exacerbate experimental autoimmune diseases such as diabetes (Luhder et al., 1998) and experimental autoimmune encephalomyelitis (animal model of human multiple sclerosis) (Karandikar et al., 1996) in animal models.
In most experimental models, the two most extensively used anti-murine CTLA4 mAbs enhanced T cell activation in vivo. Nevertheless, since different mAbs may react with different epitopes on the same region of a protein or alternatively, bind to the same epitope with different affinities, different mAbs against the same protein can have opposite effects. Thus, some monocloanal antibodies to the CTLA4 receptor may enhance T cell proliferation and activation; while other anti-CTLA4 monoclonal antibodies may inhibit T cell proliferation and activation. Accordingly, monoclonal antibodies and other agents which specifically or selectively interact with CTLA4 may be of therapeutic value in cancer, and infection, as well as autoimmune disease and transplantation.
A major impediment to the development or identification of mAbs or other agents that can be used to either activate or inactivate T cells via a CTLA4-mediated pathway is the lack of an appropriate assays for screening such agents. Conflicting results have demonstrated that an in vitro assay cannot serve as an accurate predictor of the functionality of antibodies to the B7 receptors in vivo. For example, anti-CD28 mAb have been shown to provide potent costimulatory activity for T cell activation in vitro (Jenkins et al., 1991), but have little effect on tumor growth in vivo (Leach et al., 1996). In contrast, investigators have found that administration of anti-CTLA4 mAb induces rejection of tumors and exacerbates autoimmune diseases in vivo (Leach et al.,) while anti-CTLA4 mAbs have been shown to either enhance or inhibit T cell activation in vitro (Krummel and Allison, 1995; Walunas et al., 1994) These results demonstrate that the functional effect of agents targeting receptors for B7 ligands, particularly the CTLA4 receptor, cannot be accurately tested in vitro. Accordingly, it is desirable to have additional tools for screening agents, particularly monoclonal antibodies, that either inhibit or enhance CTLA-4 signaling.

Animal model for identifying agents that inhibit or enhance CTLA4 signaling

The Ohio State University Research Foundation


An improvement is proposed in the method for the flame hydrolysis of a silicon-containing gas, e.g., silicon tetrachloride, to produce fine silica particles to be deposited on a substrate in a process for the preparation of a silica glass preform of optical fibers by using a fivefold concentric multiplex-tube burner nozzle. In contrast to the conventional way for the flame hydrolysis in which the center or first nozzle opening of the burner serves for ejection of a mixture of silicon tetrachloride and oxygen and hydrogen is ejected from the third nozzle opening while argon is ejected from the second nozzle opening inbetween, the gas ejected from the second nozzle opening is, instead of argon alone, a mixture of oxygen and argon in a specified mixing proportion so that deposition of silica particles on the nozzle end can be prevented even when the feed rate of silicon tetrachloride is relatively high.

The present invention relates to an improvement in the method for the preparation of a preform of optical fibers or, more particularly, to an improvement in the method for the preparation of a glassy preform of optical fibers by the deposition of fine silica particles formed by the flame-hydrolysis of a silicon-containing starting material for the glass in an oxyhydrogen flame.
As is known, a preform of optical fibers of, for example, fused silica glass is prepared by the deposition of silica soot or fine particles of silica, formed by the combustion of a silicon-containing starting gas such as silicon tetrachloride which is introduced into a concentric multiplex-tube burner nozzle together with oxygen gas and hydrogen gas to form an oxyhydrogen flame in which the silicon-containing starting gas is flame-hydrolyzed and converted into silica particles, on a substrate body of, for example, synthetic fused silica glass to form a porous body of silica followed by subsequent heating and vitrification of the porous body at a high temperature into a transparent silica glass preform. This process is called the outer-deposition CVD method or VAD method.
The concentric multiplex-tube burner nozzle used here has several nozzle openings including the center nozzle opening and a plural number of ring-wise nozzle openings from which the silicon-containing starting gas for the glass material, inert diluent gas, hydrogen gas and oxygen gas are ejected either separately or as a mixture to cause burning of an oxyhydrogen flame and flame hydrolysis of the starting gas for the glass material in the flame. One of the serious problems encountered in the continuous running of this flame-hydrolysis reaction is that the nozzle end of the burner is sometimes overheated by the oxyhydrogen flame resulting in premature damage or deformation of the burner nozzle if not to mention the problem that the fine silica particles produced from the silicon-containing starting gas by the flame hydrolysis are deposited more or less on the nozzle end of the burner eventually resulting in blocking of the nozzle openings by the growth of the silica particle deposition.
In view of the above mentioned problems, an improved method is disclosed in Japanese Patent Publication No. 61-44822, according to which an inert gas is ejected from a ring-wise nozzle opening of a concentric multiplex-tube burner nozzle which is between two nozzle openings, one, for the ejection of hydrogen gas or a mixture of a silicon-containing gas and hydrogen gas and, the other, for the ejection of oxygen gas. This method, however, has a practical disadvantage that the efficiency of combustion to form an oxyhydrogen flame cannot be high enough because, when the rate of ejection of the silicon-containing starting gas is increased with an object to improve the productivity, the flow rate of the inert gas also must be increased correspondingly since otherwise the nozzle openings are readily blocked by the rapid deposition of silica particles thereon. This problem of silica particle deposition on the nozzle end can be partly solved by providing an intermediate nozzle opening for the ejection of an inert gas between two nozzle openings, one, for the ejection of a mixture of oxygen and the silicon-containing starting gas and, the other, for the ejection of hydrogen gas though at the sacrifice of the efficiency of the reaction to cause a decrease in the effective yield of silica deposition on the substrate.

Preparation of a preform of optical fibers


A device for irradiating tissue encompassing at least one electron source for generating an electron beam, numerous radiation heads that are firmly and annularly arranged in a supporting frame around an isocenter of the device and emit radiation towards the isocenter, and one beam guidance system to guide the electron beam in the housing towards the radiation heads. The beam guidance system has been built as a polygon, especially as a pentagon arranged like a ring around the isocenter, in which case media for deflecting the electron beam have been placed at every corner point of the polygon.

Tissue irradiation units are well known from current technological advances. To achieve their aim, the patient is placed on a table in an isocenter of the irradiation device so his/her tissue can be irradiated. The irradiation device is equipped with a radiation source that generates radiation, which will eventually be guided to one or even several radiation heads located within the device. Generally, a device rotates the radiation heads around the object to be irradiated in such a way that the beams always reach the target volume sequentially from various directions. The target volume receives a relatively large radiation dose in this way, while the healthy surrounding tissue is protected. These known devices have the disadvantage that the precise rotation of the radiation heads is difficult to carry out from the technical viewpoint owing to the size of the masses to be moved.
In order to simplify a tissue irradiation device, EP 1 311 322 B1 suggests the firm arrangement of numerous radiation heads within a housing. What that invention foresees is a common radiation source for all radiation heads, in which case a radiation splitter splits the radiation to the various radiation heads. After the splitting, the individual beams are in each case deflected several times by a beam guidance system until they are finally guided to the radiation heads, which are largely arranged in the shape of a ring around the tissue to be irradiated. In this design, the arrangement of the radiation heads leads to a relatively large housing size.

Tissue irradiation device with at least one electron source and numerous radiation heads


An energy management circuit (100) for use with one or more rechargeable cells (201) is capable of prohibiting discharge in response to temporal or other inputs. In one embodiment, a control circuit (102) applies a control signal to a discharge control node (105) when a charging current is applied for less than a charging duration threshold. The control signal causes a discharge disconnect switch (202) to open. In another embodiment, the control circuit (102) applies the control signal to the discharge control node (105) after failing to detect a charging current for at least a non-charging duration threshold. Discharge can again be allowed by applying a charging current for at least a reset duration.

1. Technical Field
This invention relates generally to rechargeable batteries, and more specifically to rechargeable batteries with safety circuits.
2. Background Art
Portable electronic devices, such as cellular telephones, pagers, and two-way radios for example, derive their portability from batteries having rechargeable cells. These batteries allow these devices to slip the surly bonds of power supplies tethered to the wall and to travel wirelessly with the user wherever he may go.
While some may think that a rechargeable battery is simply a rechargeable cell and a mechanical housing, nothing could be further from the truth. Rechargeable battery packs often include circuit boards, electronic circuitry, mechanical housings or structural assemblies, and electronic or mechanical protection components. Simply put, a rechargeable battery pack is a system of components working in harmony to safely deliver power to a portable electronic device.
One of the most fundamental circuits in a battery pack is the protection circuit. Rechargeable battery performance, especially with respect to those having cells constructed of lithium-based materials, may be severely compromised if the cell within the battery pack is over or under charged. For this reason, most all battery packs today include one form of safety circuit or another. Typical safety circuits include voltage and current limits. As such, when the voltage across the cell in a battery pack becomes too high or too low, the safety circuit will open switches within the pack, thereby temporarily "turning off" the battery pack. Similarly, if the current flowing either into or out of the cell gets too high, the safety circuit will momentarily turn off the battery pack.
Not too long ago, most rechargeable battery packs were detachable from the devices they powered. For instance, a mobile telephone user could remove the battery pack from the mobile telephone for charging or replacement. However, as today's modern electronic devices are becoming smaller and smaller, many devices are integrating the rechargeable battery into the device. As such, the user does not have access to the battery pack.
One problem associated with integrated batteries is that of host current drain during storage. Some electronic devices drain small amounts of current from the battery pack even when they are OFF. As such, an issue of concern is the amount of current drain that occurs between the electronic device with the integrated battery is manufactured and the time when it is first charged by a consumer. During this time, which could be months, the circuitry in the host device can be generally consuming energy. This energy consumption causes battery discharge. If the charge level decreases too much, a condition known as over-discharge, the performance of the battery can be compromised
There is a need for a battery assembly that can reduce an amount of current being drained from the battery during storage or similar conditions.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.

Battery and energy management circuit with temporal storage mode


A data conversion device is provided with a data converting means that sequentially converts first data into second data of the number of second bits, wherein an analog signal is quantized into the first data by the number of first bits, and the first and second data can be first and second maximum values, respectively. The data converting means is comprised of a first conversion means (steps 21 and 23) that, when a value of the fast data is not the first maximum value, converts the first data to the second data by adding 0 to a lower bit side of the first data and a second conversion means (steps 21 and 24-26) that converts the first data to the second data so that, when a value of the first data is the fast maximum value, a value can be made larger, in accordance with a value be-fore or after the first data, than the data of the number of second bits obtained by adding 0 to the lower bit side of the first data. With the structure, when the data obtained by quantizing an analog signal is converted to data with the number of more bits, a rounding error by quantizing is improved as much as possible.

One of conventional standards relating to data recorded on a compact disk (hereafter, a "CD") is based on a sampling frequency of 44.1 [kHz] and a quantization bit rate of 16 bits. Thus, the size of digital data for a CD or the like is represented using 16-bit representations corresponding to the values of 1 through −1. That is to say, encoding is carried out by dividing the values of 1 to −1 by the number of values that can be represented by the quantization bit rate and determining 16-bit numerical values corresponding to the individual values resulting from division. Quantization for a CD is performed by dividing the values of 1 to −1 with the accuracy of the 15th power of 2 excluding a sign bit. That is to say, in general, 16-bit values from 0x7FFF to 0x8000 are related to the original values of 1 to −1 as shown in FIG. 11. When the quantization bit rate is 24-bit, 0x7FFFFF to 0x800000 correspond to 1 to −1, as also shown in FIG. 11.
FIG. 12 shows a configuration of a recording device for recording on a CD. As shown in the figure, to record on a CD 123, audio signals for right and left channels are converted to 16-bit digital signals by a 16-bit A/D converter 121. The digital signals are written on the CD 123 by writing means 122. When a maximum voltage that can be input to the A/D converter 121 is denoted as Vdd and an input voltage on the A/D converter 121 associated with an analog audio signal is denoted as Vin as shown in FIG. 15, a voltage corresponding to 16-bit 0x0001 is a value obtained by dividing Vdd by the 15th power of 2, and Vin is represented by a multiple of that value. In other words, the A/D converter 121 encodes an analog audio signal input thereto according to the equation below to convert it into a 16-bit digital signal. In the process, a small variation in voltage below a voltage equal to Vdd divided by the 15th power of 2 will be rounded. Also, when Vin=Vdd, the corresponding value is 0x8000, but because the MSB is a sign bit, the value is rounded to 0x7FFF.
[Formula 1]
Known devices that thus outputs rounded input data include a device described in Patent Document 1, for example. When outputting input data with resolution decreased to a quarter, for example, the device first sets the initial input data as a reference value, then rounds the input data by dividing the data by 4 and dropping or rounding off the remainder, and outputs the resulting data. For subsequent input data having a variation from the reference value smaller than 4, the device does not change output data, i.e., outputs the rounded reference value. When subsequent input data varies from the reference value by 4 or greater, the device replaces the output data with a value obtained by rounding that input data and also updates the reference value to that input data. In short, the device permits change of output data only when a variation equivalent to reduction in resolution is found in input data, thereby ensuring smooth variation in output data.
Patent Document 2 describes a technique for rounding z-bit input data to z/2-bit data. This technique determines which bits to remove for rounding according to bits being used.
FIG. 13 illustrates a basic configuration of a reproducing device for reproducing audio recorded on a CD. For reproduction, an audio signal recorded on CD 133 is read as 16-bit data via a servo mechanism 134 and converted to an analog signal in a 24-bit D/A converter 135. The analog signal passes through an amplifier and volume 136 to drive loudspeakers 137.
Digital Signal Processors (DSP) and D/A converters, which are recent digital-signal processing ICs, have improved bit precision and are mostly 24-bit as the D/A converter 135. To input 16-bit data from the CD 133 to the 24-bit D/A converter 135, it is necessary to convert the 16-bit data to 24-bit data. Accordingly, data from the CD 133 is converted to 24-bit data by using the data from the CD 133 as upper 16-bit data and adding zeros as lower 8 bits to make 24-bit data, as shown in FIG. 14. The figure shows 16-bit CD data corresponding to original values from 1 to −1 as well as 24-bit data after conversion for use in the D/A converter and/or a DSP.
Patent Document 1: Japanese Patent Application Laid-Open No. H05-35258
Patent Document 2: Japanese Patent Application Laid-Open No. 2007-280082

Data converting device, program and method