A method for facilitating a reduction in reconstructed image noise in a computed tomography imaging system. The method includes generating projection data, characterizing a noise distribution of the projection data, performing an adaptive noise reduction operation on the projection data using the noise distribution characterization, and filtering the projection data.

This invention relates to tomographic imaging, and more particularly to methods and apparatus for reducing reconstructed image noise in a computerized tomographic (CT) imaging system.
In at least one known CT imaging system configuration, an x-ray source projects a fan-shaped beam which is collimated to lie within an X-Y plane of a Cartesian coordinate system and generally referred to as an xe2x80x9cimaging planexe2x80x9d. The x-ray beam passes through an object being imaged, such as a patient. The beam, after being attenuated by the object, impinges upon an array of radiation detectors. The intensity of the attenuated beam radiation received at the detector array is dependent upon the attenuation of an x-ray beam by the object. Each detector element of the array produces a separate electrical signal that is a measurement of the beam attenuation at the detector location. The attenuation measurements from all the detectors are acquired separately to produce a transmission profile.
In known third generation CT systems, the x-ray source and the detector array are rotated with a gantry within the imaging plane and around the object to be imaged so that the angle at which the x-ray beam intersects the object constantly changes. A group of x-ray attenuation measurements, i.e., projection data, from the detector array at one gantry angle is referred to as a xe2x80x9cviewxe2x80x9d. A xe2x80x9cscanxe2x80x9d of the object comprises a set of views made at different gantry angles, or view angles, during one revolution of the x-ray source and detector.
In an axial scan, the projection data is processed to construct an image that corresponds to a two-dimensional slice taken through the object. One method for reconstructing an image from a set of projection data is referred to in the art as the filtered back projection technique. This process converts the attenuation measurements from a scan into integers called xe2x80x9cCT numbersxe2x80x9d or xe2x80x9cHounsfield unitsxe2x80x9d, which are used to control the brightness of a corresponding pixel on a cathode ray tube display.
In some known imaging systems, using sub-millimeter scanning speeds, the demands on the peak and sustained x-ray source power increase substantially resulting in a signal loss to the detector. Additionally, a signal loss can be caused by gaps between individual detector cells resulting in the number of detected x-ray photons decreasing by more than a factor of two thereby facilitating a reduction in image quality. Additionally, an increased x-ray dosage may produce adverse effects in a human body, therefore, a reduced x-ray photon flux facilitates a reduction in the x-ray dosage a patient receives since an x-ray dosage received by a patient should be minimized. This is generally accomplished with a reduced x-ray tube current, which typically results in a decreased number of x-ray photons.
In one aspect, a method for facilitating a reduction in reconstructed image noise in a computed tomography imaging system is provided. The method includes generating projection data, characterizing a noise distribution of the projection data, performing an adaptive noise reduction operation on the projection data using the noise distribution characterization, and reconstructing an image.
In another aspect, a method for facilitating a reduction in reconstructed image noise in a computed tomography imaging system is provided. The method includes generating projection data, pre-processing the projection data using at least one of an offset correction, a primary speed correction, a reference channel correction, and an air-calibration. The method also includes characterizing a noise distribution of the projection data wherein characterizing a noise distribution includes generating an air calibration vector, performing a polynomial fit of the air calibration vector to generate a bowtie shape vector and approximating a standard deviation of the noise distribution using the bowtie shape vector in accordance with       σ              (      γ      )        =                              B                                (            γ            )                                                        p                                      (              γ              )                                                  p                          (                      γ            0                    )                      .
The method also includes performing an adaptive noise reduction operation on the projection data using the noise distribution characterization, filtering the projection data in accordance with pr(xcex3)=p(xcex3)xe2x88x92xcex1(xcex3)└p(xcex3)xe2x88x92pf(xcex3)┘, and reconstructing an image.
In a further aspect, a computed tomographic (CT) imaging system for facilitating a reduction in reconstructed image noise is provided. The computed tomographic (CT) imaging system includes a detector array, at least one radiation source, and a computer coupled to the detector array and radiation source and configured to generate projection data. The computer is also configured to characterize a noise distribution of the projection data, perform an adaptive noise reduction operation on the projection data using the noise distribution characterization, and reconstruct an image.
In still a further aspect, a computed tomography (CT) imaging system for facilitating a reduction in reconstructed image noise is provided. The computed tomography (CT) imaging system includes a detector array, at least one radiation source, and a computer coupled to the detector array and radiation source and configured to generate projection data, pre-process the projection data using at least one of an offset correction, a primary speed correction, a reference channel correction, and an air-calibration. The computer is also configured to characterize a noise distribution of the projection data, wherein to characterize a noise distribution includes generating an air calibration vector, performing a polynomial fit of the air calibration vector to generate a bowtie shape, approximating a standard deviation of the noise distribution using the bowtie shape vector in accordance with       σ              (      γ      )        =                              B                                (            γ            )                                                        p                                      (              γ              )                                                  p                          (                      γ            0                    )                      .
The computer is also configured to perform an adaptive noise reduction operation on the projection data using the noise distribution characterization, filter the projection data in accordance with pr(xcex3)=p(xcex3)xe2x88x92xcex1(xcex3)└p(xcex3)xe2x88x92pf(xcex3)┘, and reconstruct an image.
In yet another aspect, a computer readable medium encoded with a program executable by-a computer for facilitating a reduction in reconstructed image noise in a computed tomography imaging system is provided. The program is configured to instruct the computer to generate projection data, characterize a noise distribution of the projection data, perform an adaptive noise reduction operation on the projection data using the noise distribution characterization, and reconstruct an image.
In yet another further aspect, a computer readable medium encoded with a program executable by a computer for facilitating a reduction in reconstructed image noise in a computed tomography imaging system is provided. The program is configured to instruct the computer to generate projection data, pre-process the projection data using at least one of an offset correction, a primary speed correction, a reference channel correction, and an air-calibration. The program is also configured to characterize a noise distribution of the projection data wherein to characterize a noise distribution includes generating an air calibration vector, performing a polynomial fit of the air calibration vector to generate a bowtie shape vector and approximating a standard deviation of the noise distribution using the bowtie shape vector in accordance with       σ              (      γ      )        =                              B                                (            γ            )                                                        p                                      (              γ              )                                                  p                          (                      γ            0                    )                      .
(The program is also configured to instruct the computer to perform an adaptive noise reduction operation on the projection data using the noise distribution characterization, filter the projection data in accordance with pr(xcex3)=p(xcex3)xe2x88x92xcex1(xcex3)└p(xcex3)xe2x88x92pf(xcex3)┘, and reconstruct an image.

Method and apparatus for noise reduction in computed tomographic systems

GE Medical Systems Global Technology Company, LLC


A vehicle condenser which has a substantially parallelepipedic shape and stacked plates, which are parallel to a substantially vertical plane and define alternate coolant chambers and refrigerant chambers between each other. The vehicle condenser is divided into three consecutive groups of refrigerant chambers and includes at least one combination, on one side of the vehicle condenser, of a larger refrigerant outlet, that leads a main flow of refrigerant from one group of refrigerant chambers to a larger refrigerant inlet of a following group of refrigerant chambers, and, vertically opposite to the larger refrigerant outlet, a smaller refrigerant outlet, that leads a residual flow of refrigerant from the one group of refrigerant chambers to a smaller refrigerant inlet of the following group of refrigerant chambers.

Rankine cycles driven by exhaust gases or recycled exhaust gases can be used in vehicles to reduce the fuel consumption and the emission of CO2. If a Rankine system is properly designed, most of the heat in the exhaust gases can be recovered. In the Rankine cycle a refrigerant is brought from liquid to gas phase in an evaporator in a high pressure state and heat is exchanged from a heat source. Gas is expanded from high pressure to low pressure in an expander and useful work is extracted from the cycle. The gas is condensed at low pressure in a condenser and heat is exchanged towards a heat sink. In a vehicle the heat sink is a low temperature radiator system. The formed fluid can after condensation be gathered in a tank and pumped to a high pressure level and fed to the evaporator again to form a closed cycle.
The disclosure particularly relates to condensers for vehicles, which are built as plate heat exchangers with fluid circuits that are integrated in plate bundles.


An encryption/decryption device, system and method for providing secure communication over a communication channel. The encryption device includes a radio interface unit connected to a conventional radio, wherein the interface unit selectively couples a codec, signal processor and modem to the transmit and receive path during secure operation. The codec digitally encodes non-secure analog signals and places them in pulse code modulated format. The signal processor then compresses the pulse code modulated signals into voice coded and then digitally encrypted NRZ signals which are then input into the conventional radio for modulating a carrier frequency on an occupied bandwidth approved for 15 KHz to 25 KHz, or as little as 11.4 KHz, spaced channels. The modem can input the digitally encrypted signals using modified frequency modulation to place the modified digitally encrypted signals substantially within the voice passband of 300 Hz to 3200 Hz. The device, system and method incorporates a master prologue sent prior to voice information at a BPS rate different from that of the voice BPS rate. The voice information is sent in blocks with a plurality of resynchronization data frames of bits interlaced between a plurality of voice frames of bits to allow highly reliable late entry and re-entry access. A conventional repeater system can be selectively controlled by a controller device of the present invention for demodulating, error correcting and recompressing the master prologue without descrambling the digitally encoded voice information.

1. Field of the Invention
The present invention relates to the art of cryptography and, more specifically, to the implementation of improved techniques for achieving voice and/or data communication security over a radio and/or telephone channel.
2. Description of the Relevant Art
Cryptography generally relates to the art of protecting sensitive communications against unauthorized access. The proliferation of electronic eavesdropping into sensitive police and military communications has spurred industry to create encryption/decryption devices which prevent such eavesdropping.
Techniques of encrypting or scrambling of radio or telephone signals can take on many forms. Scrambling can go from simple analog encryption to sophisticated digital encryption. Analog scrambling, which makes use of filtering schemes, inverting schemes, time domain schemes and split-band audio schemes is generally easier to incorporate into the radio communication channel than digital scrambling, however, it is much easier for unauthorized users to unscramble an analog-scrambled voice than it is for them to unscramble digital-scrambled voice. Digital encryption, is more difficult to unscramble since it converts the voice to binary bits, scrambles the bits, then transmits the scrambled bits over the communication channel. Thus, the digital system makes unauthorized descrambling or deciphering difficult since all the intruding user "sees" is scrambled bit representation of voice and not scrambled voice itself.
Generally, the three functional blocks used in a digital speech encryption device are: (1) voice coder/decoder (vocoder); (2) encryption/decryption algorithm; and (3) modulation/demodulation methodology. The vocoder functions by first coding analog voice samples and then compressing those samples into a smaller number of binary bits. Thus, when combined with a suitable modulation methodology, the vocoder allows transmission over a communication channel of a smaller, specified bandwidth, and provides intelligible reproduction or decoding via the decode block on the receive end.
First generation vocoders were linear predictive coders (LPC-10) as discussed in Federal Information Processing Standards Publication (FIPS PUB) No. 137, U.S. Dept. of Commerce, NTIS, 5285 Post Royal Road, Springfield, Va. 22161, published on Nov. 28, 1984. The relatively poor voice quality reproduced by LPC coders spurred the industry to develop other vocoders, such as: (1) continuously variable slope delta (CVSD) modulation, described in U.S. Pat. No. 4,167,700, (2) sub-band coding described in T. P. Barnwell et al., "A Real-Time Speech Sub-Band Coder Using the TMS 32010," IEEE Southcon, (1984), and (3) hybrid sub-band coders described in U.S. Pat. No. 4,817,146.
Most of the recently developed vocoders known in the industry are described in "An Evaluation of 4800 BPS Voice Coders" Proceedings of ICASSP (1989). Such vocoders include Vector Adaptive Predictive Coder (VAPC) and Code or Vector Sum Excited Linear Predictive (CELP or VSELP) type coders. Other recent vocoders include Improved Multi-Band Excitation (IMBE) voice coders as described in Proceedings of ICASSP, (1990) and in U.S. Pat. No. 5,081,681 (herein incorporated by reference), and Sinusoidal Transform Coder (STC), as described in U.S. Pat. Nos. 4,885,790 and 4,937,873 (herein incorporated by reference). In addition, there are some very low bit rate (BPS) laboratory voice coders being developed. An exemplary said voice coder is described in Y. J. Liu, "A High Quality Speech Coder at 600 BPS," Proceedings of ICASSP (1990), pp 645-648.
Although vocoders of the conventional art can be adequately interfaced with many different and suitable modulation methodologies depending upon the channel characteristics, typical vocoders must transmit large numbers of bits per second (BPS), and/or utilize sophisticated forward error correction/detection techniques in order to achieve commercial quality voice reproduction. As defined herein "commercial quality voice reproduction" is reproduction which is considered equal to or near equal to the original analog voice normally reproduced through the communication channel. For example, CVSD requires 12,000 BPS while sub-band coding and hybrid sub-band coding requires approximately 9,600 BPS to reproduce commercial quality voice through radios. CELP type vocoders require 4,800 BPS and the IMBE and STC vocoders generally require 2,400 BPS to achieve commercial quality voice reproduction through radios.
Conventional vocoders typically reproduce commercial quality voice in the 0 to 1% bit error rate (BER) condition. With forward error correction, conventional vocoders typically reproduce intelligible voice up to the 5% to 8% BER condition. Thus, the vocoder BPS rates described above do not include the forward error correction/detection required to correct for a constantly varying BER of 0% to 10% encountered in land mobile radio channels (i.e., channels subject to fading and multipath conditions). Typical forward error correction methods such as cycle redundancy checks, parity checks, matrix extraction, bit averaging, Hamming coding, Golay coding, and soft decision, generally require additional or redundant bits be transmitted to ensure data integrity at the receive end. Other methods to help intelligibly receive data include bit interleaving, block or convolution coding.
Forward error correction techniques often require an additional 25-100% BPS be transmitted depending upon the vocoder, with the recent vocoders (i.e., VAPC, CELP, VSELP, IMBE and STC) requiring higher redundancy because of the increased importance of each bit transmitted. While a 10% to 25% redundancy is generally appropriate for a sub-band coder method, a 30% to 100% redundancy is often required for many of the recently developed vocoders described above. Thus, for example, the actual vocoder data rate required for a 2,400 BPS vocoder may be approximately 3,600 to 4,800 BPS in order to operate intelligibly in a land mobile radio. When system overhead is included, such as system synchronization, commands, and encryption initialization, the actual transmitted data rate may be over twice the actual vocoder rate.
The next functional block, or encryption/decryption block, is generally designed either to protect classified information or to protect sensitive but unclassified information. One conventional encryption technique used to prevent eavesdropping of sensitive but unclassified information is the Data Encryption Standard (DES). DES has become the standard algorithm used for sensitive, non-military applications such as, e.g., police communication. DES is fully explained in FIPS Pub No. 46, U.S. Dept. of Commerce, NTIS, 5285 Post Royal road, Springfield, Va. 22161, published on Jan. 22, 1988.
Typically, digital signals are processed in non-return-to-zero (NRZ) format. NRZ, as well as other formats, are often not reliable over communication channels. Thus, the third functional block, comprising the modulation/demodulation methodology, is needed. Modulation/demodulation methodologies are known in the art and can be described in M. Schwartz, Information, Transmission, Modulation and Noise, McGraw Hill, (3rd Edition, 1980); Ferrel G. Stremler, Introduction to Communication Systems, Addison-Wesley Publishing Company, Inc., (2nd Edition, 1982); I. Korn, Digital Communications, Van Nostrand Reinhold Company, Inc., (1st Edition, 1985); and J. Proakis, DigitaI Communications, McGraw Hill, (2nd Edition, 1989). It is important when modulating or demodulating in a communication path, that efficient use be made of the frequency spectrum. As generally utilized for conventional and trunked radios, constant envelope modulation techniques, such as frequency shift keying (FSK), or phase shift keying (PSK), may often cause the communication medium to occupy too wide a transmitted bandwidth for the governmental standard of 15 KHz to 25 KHz spaced radio channels. Also, the transmitted frequency components representing the digitally encrypted signals generally exceed the voice passband of 300-3200 Hz required in conventional radio and telephone systems when operating at the required data rates/hertz for digital secure voice communications.
To aid in the discussion and understanding of the present art, the following terms are defined herein: "conventional radios" are defined as frequency modulated (FM) and phase modulated (PM) analog radios that may contain nonlinear amplifiers and designed for 15 to 25 KHz spaced radio channels as defined in FCC Rules and Regulations Part 90, dated Feb. 15, 1989. Conventional radios may include trunked radios used in a trunked group as defined in FCC Rules and Regulations Part 90, dated Feb. 15, 1989. "15 KHz to 25 KHz spaced radio channels" refer to the separation between the center carrier frequency, measured in Kilohertz (KHz), of each radio channel as designated and listed in FCC Rules and Regulations Part 90, dated Feb. 15, 1989. "Linear Amplifier" is defined as a radio final amplifier, wherein the output is linearly proportional to the input. Generally, a signal requiring a linear amplifier will not work properly with a linearized or nonlinear amplifier. A linear amplifier is generally regarded as an FCC class A amplifier. "Linearized Amplifier" is defined as a radio final amplifier, wherein the output is mostly linearly proportional to the input. Generally, a signal requiring a linearized amplifier will also work properly with a linear amplifier, but not with a nonlinear amplifier. A linearized amplifier is generally regarded as an FCC class AB amplifier. "Nonlinear Amplifier" is defined as a radio final amplifier, wherein the output is not linearly proportional to the input. Generally, a signal that will work properly with a nonlinear amplifier will also work properly with a linear or linearized amplifier. A nonlinear amplifier is generally regarded as an FCC class C amplifier. "Conventional Repeater" is defined as a conventional radio that is used to expand the coverage by receiving and re-transmitting the signal to a satellite receiver, or receivers.
The industry has increased non-linear modulation efficiency using continuous phase modulation techniques, such as continuous phase frequency shift keying (CPFSK) including minimum shift keying (MSK) that have produced bandwidth efficiencies of up to 2 bits/Hz. However, one of the most popular and bandwidth efficient of these methods, MSK, requires a minimum separation of the transmitted frequencies that equals one-half of the BPS rate. Thus, for conventional digital encryption techniques employing MSK and requiring 9,600 BPS, as described in U.S. Pat. No. 4,817,146, a frequency separation of 4,800 Hz is needed thereby requiring frequency components of 2,400 Hz and 7,200 Hz be transmitted. It is believed that this constant frequency separation or shift of 4,800 Hz may exceed the design of some conventional phase modulated radios. An additional problem associated with conventional digital voice encryption modulation techniques is that they often require linearized response amplifiers and filters. Such is the case in U.S. Pat. No. 4,167,700 which describes an improved repeater which contains a "regeneration" means for retiming and reshaping the signal at remote locations without descrambling the signal. This method requires compatibility with linearized amplifiers and thus is not applicable to conventional radios and repeaters. Any of the above reasons, or others, may force consumers to dispose of their conventional radio equipment, including associated repeaters, and purchase new radio systems (i.e., radio equipment and repeaters) in order to use digital encryption/decryption with their radios.
As stated above and discussed in U.S. Pat. No. 4,852,166, another problem that typically arises in conventional digital voice encryption devices is that the transmitted BPS rates require transmission of frequency components that exceed the voice pass-band of 3200 Hz (approximately 300 to 3,200 Hz) specified by the FCC for conventional and trunked analog radio and telephone systems. One such system is described in U.S. Pat. No. 4,817,146. Patent '146 specifies a fairly high transmitted frequency component of approximately 7200 Hz. To compensate for the transmitted high frequencies, a low pass filter is modified or bypassed in the radios and the level of modulation deviation is often lowered to remain within the approved occupied bandwidth of 15 KHz to 25 KHz spaced channels. Oftentimes, lowering the modulation deviation results in a reduction of transmitter efficiency. To compensate for a loss of transmitter efficiency, radio transmitter power must generally be boosted. As shown in the FCC Rules and Regulations, Title 47 Code of Federal Regulations (CFR) Part 22.508 dated Oct. 1, 1988, a low-pass filter is required before the modulator in a conventional and trunked radio that attenuates audio frequency components above the voice pass-band from 3 KHz to 15 KHz by at least a scale of 40 log.sub.10 (f/3) decibels (db) where "f" is the audio frequency in KHz. Thus, the digital encryption device described in Patent '146 (which transmits a 7200 Hz high frequency component), must modify or bypass this low-pass filter because the transmitted signal strength (power) of the high frequency component would be attenuated by approximately 15 db below the low frequency component (i.e., 2400 Hz). This would result in a conventional radio only transmitting the high frequency component at a power level substantially equal to 1/32nd of the low frequency component transmitted power, rendering the device virtually useless.
Also, as discussed in the FCC Rules and Regulations Part 2.202 dated Oct. 1, 1987 and Part 22.507 dated Oct. 1, 1988, the formula to calculate the necessary bandwidth occupied by a typical FM radio emission is B.sub.n =2M+2DK, wherein:
B.sub.n =necessary bandwidth in hertz. PA1 M=maximum modulation frequency in hertz. PA1 D=peak frequency deviation, i.e. half the difference between the maximum and minimum values of the instantaneous frequency (i.e., instantaneous frequency in hertz is the time rate of change in phase in radians divided by two) PA1 K=an overall numerical factor which varies according to the emission and which depends upon the allowable signal distortion: K=1 for typical FM Radio. PA1 B.sub.n =2(7200 Hz)+2(10000 Hz/2)(1) PA1 B.sub.n =14400 Hz+10000 Hz PA1 B.sub.n =24400 Hz or 24.4 KHz PA1 B.sub.n =2(7200 Hz)+2(5000 Hz/2)(1) PA1 B.sub.n =14400 Hz+5000 Hz PA1 B.sub.n +19400 Hz or 19.4 KHz
The maximum occupied bandwidth for the digital encryption apparatus described in Patent '146 when transmitting a 7200 Hz frequency component is calculated as, M=7200 (highest frequency) and D=maximum 10000/2 Hz, or 5 KHz as described in Part 22.507 above, the maximum occupied bandwidth could be:
By lowering the peak deviation (D) to 5000 Hz, which is believed to be the lowest peak deviation that will provide satisfactory results (+/-2.5 KHz), the necessary occupied bandwidth should be:
Thus, the occupied bandwidth of the device described in Patent '146 should fall within the allowable 20 KHz for digital voice transmissions on 15 KHz to 25 KHz spaced channels if the peak deviation is substantially lowered from the maximum 5 KHz allowed.
The FCC Rules and Regulations concerning occupied bandwidth, frequency deviation, voice pass band and resulting radio designations are fully explained in Title 47, Code of Federal Regulations (CFR) Parts 2, 22, and 90 available at the U.S. government printing office.
New digital radio standards are currently being developed by both the U.S. government (Federal Standard 1024) and the public safety community (e.g., Associated Public Safety Communication Officers, Inc. (APCO) Project 25) to achieve increased spectrum efficiency. The new standards may ultimately narrow the channel spacing in a portion of the spectrum to about 6.25 KHz, versus the current 15 KHz to 25 KHz spacing. Examples of modulation methodologies that are being considered to obtain this efficiency are 4-ary FSK, generalized tamed frequency modulation (GTFM), quadrature differential phase shift keying (QDPSK), pi/4 shift QDPSK, C4FM, and QPSK-compatible (QPSK-C). These modulation techniques have not achieved the 6.25 KHz efficiency when designed into conventional radio transmitters without wholesale redesign of the radio itself. It is believed that there are currently no plans or discussions underway that will allow conventional radios to be forward compatible to the new digital radios in the new digital mode, regardless of the occupied bandwidth required by older conventional radios.
As explained above, digital voice coders typically used in digital voice encryption applications remain intelligible in the BER condition. That is, the voice typically remains intelligible even though the received information contains wrong information (i.e., bit errors) in the range of 0% to 8%. However, it is also commonly known that the critical control information must be interpreted correctly, i.e., interpreted error-free by the receive unit in order for the voice to be decrypted properly. Critical control information typically includes system synchronization, encryption initialization, a method of identifying the encryption code key used and a method of identifying units authorized to receive the information.
Typical digital transmission methods of the prior art use either asynchronous methods or synchronous methods at a fixed speed. The fixed speed means the BER condition for the critical control information is the same as the voice information since both blocks are sent at the same speed. However, only the control information must be interpreted error-free. Asynchronous methods include the synchronization bits within the data bits. Synchronous methods separate the synchronization bits from the data bits. However, when a fixed speed is utilized, the device then becomes limited to only the application for which it was designed. A recent application of the new digital radios suggests combining both voice and data into the same bit stream at a fixed speed, but this application has not been shown to be suitable with conventional radios.
Generally, to ensure correct reception when using synchronous techniques, the critical control information is redundantly transmitted such that each subblock of information (e.g., encryption initialization or re-initialization subblocks) is repeated several times whenever the critical control information is transmitted. Also, the entire critical control information block is repeatedly transmitted as often as possible, often more than twice per second, to ensure the receiving units remain in synchronization throughout the message. Retransmitting the critical control information throughout the message also allows those units that are lost to "enter the conversation late" and decrypt the remainder of the message. This is commonly known as "late entry". Also, retransmitting the critical control information throughout the message allows the message to be more secure by continuously re-initializing and changing the encryption mapping via transmission of new encryption initialization vectors (IV).
Redundant transmission of the critical control information is necessary to compensate for the fading and multipath effects associated with land mobile radio channels. These effects, known as Rayleigh fading to those skilled in the art, cause the transmitted signal to fade by an average of -20 db (decibels) for an average length of 45 milliseconds (ms) per occurrence. Also, as the carrier frequency band increases, the occurrence of fades per second increases which typically results in comparatively poorer system reliability at frequency bands such as 800 MHz to 900 MHz versus 150 MHz to 450 MHz.
A conventional digital encryption device that uses synchronous methods is described in U.S. Pat. No. 4,757,536. Patent '536 utilizes a fixed speed and a very redundant "preamble" data format for transmitting the initial critical control information. This redundant preamble cannot be repeated throughout the message without losing a large portion of the transmitted voice data, or without allowing for a late entry so infrequently as to be deemed virtually useless. Thus, subsequent re-synchronization, encryption re-initialization and other control information that allows for late entry in this method is transmitted as header information only once per data frame and thereby is not as reliable as the initial preamble. Where the long preamble format virtually assures reliable initial synchronization at the beginning of a message, one error during the re-initialization of the encryption subsequently transmitted during the same message causes the receiving unit to lose encryption synchronization, or go into a "coast" condition. As described in Patent '536, the "coast" condition occurs whenever a transmitting or receiving unit has previously received control information properly (i.e., attained a steady state) and has subsequently detected an error during re-initialization of the encryption process. The "coast" condition allows the receiving unit to then predict the correct IV and continue decrypting the message.
As taught in our co-pending parent application Ser. No. 07/621,476, a dynamic speed change can be designed to occur between the master prologue (control information) and a subsequent voice or slave prologue (voice block or secondary command/data block) depending upon the command word in the master prologue. The method of application Ser. No. 07/621,476 allows for the control information to be sent at a slower BPS to reduce the BER condition during transmission of the critical control information and allows the BPS to change as required for transmission of the appropriate voice or data information. When comparing the lower versus higher BPS rates for the same BER condition, informal tests have shown the higher BPS rates require a received signal strength of 3 db to 6 db greater than the lower BPS rates, depending upon the actual BPS rates being tested. As such, lower BPS rates provide more accurate transmission reliability. Informal tests have shown a 3 to 6 db improvement in the signal to noise ratio for the same BER condition depending upon the actual BPS rates being tested. As is readily appreciated, data applications, such as information transmitted by data terminal equipment (DTE) must also be interpreted error-free in order to use the information. Most data applications through conventional radios transmit the data in packet format, wherein the same packet of information is repeated until the receive unit responds that the packet was received correctly. The command word as taught in application Ser. No. 07/621,476 instructs the transmitter and receiver to remain at a slow speed for packet transfers of data information.
Approximately 14 million U.S. consumers have conventional radios and repeater equipment approved for the standard 15 KHz to 25 KHz spaced channels, most of which are not presently capable of being converted to include digital encryption capability. While many conventional radios have been produced for foreign countries using 12.5 KHz spaced channels, such conventional radios lack retrofittability with digital encryption techniques described herein. If the foreign format radios could be retrofitted with digital encryption, then greater bandwidth efficiency in both secure and non-secure modes could be achieved thereby providing a transition to the new narrow band digital radio standards using existing equipment. If the end user wishes to transmit data, as well as voice, conventional digital encryption devices cannot automatically transmit and receive secure signals at different data and voice transmission rates and/or data frame lengths. Nor can conventional devices permit the user to alternatively send a secure message through a DTE such as a keyboard, etc., or send a secure voice message at a slower speed for playback at the receiver at full speed.
Thus, a substantial need exists for an encryption/decryption device which can be retrofitted into existing off-the-shelf conventional radios. It also would be advantageous for the device to include re-synchronization capability with the same reliability as the initial synchronization and be capable of inputting into the conventional and trunked radio both control and encrypted voice data within the voice passband of approximately 300-3,200 Hz. Furthermore, if the device can send and receive secure information at varying BPS, the device would not be limited to only one application (i.e., voice or data). It would also be advantageous to provide a control and correction technique that can be designed into or retrofitted into conventional repeaters that controls the repeater functions during digitally encrypted transmissions and error-corrects the critical control information without descrambling the encrypted information. A need also exists for a method and device that can substantially narrow the necessary occupied bandwith below the 15 KHz to 25 KHz spaced channels while being able to use a nonlinear amplifier. Also, a need exists to provide a device which provides forward compatibility of conventional and trunked radios to the new federal standard 1024 and ApCO project 25 digital radio standards in the digital mode.

Apparatus, system and method for transmitting secure signals over narrow spaced channels


A traffic exchanging method for a mobile node in a mobile network reduces packet loss during hand-over latency, and defines new messages in order to prevent packet disorder. By defining a message indicating that earlier received packets have all been delivered, it is possible to prevent packet disorder. This has an effect of reducing packet loss and preventing packet disordering while a mobile host exchanges traffic in a mobile network. This solves the performance degradation of application layer protocol caused by packet disordering.

1. Field of the Invention
The present invention relates to a Mobile Internet Protocol version 6 (MIPv6) network, and more particularly, the present invention relates to a method of exchanging traffic for a mobile node in a MIPv6 network.
2. Description of the Related Art
The present Internet is based upon Internet Protocol version 4 (IPv4). According to IPv4, a source sends a source address and a destination address on a packet to the Internet in order to transmit traffic to a destination. An IP address used in IPv4 is composed of 32 bits so that about 4 billion (4,000,000,000) hosts can access the Internet. However, the actual number of hosts capable of accessing the Internet is remarkably small because of special addressing, sub-netting and network address allocation. In addition, owing to the generalization of the Internet and an increase in multimedia traffic, unlike in the past, endeavors have been continuously made so that various devices such as mobile nodes, information home electronics and so on in addition to computers can access the Internet. Such mobile nodes and information home electronics such as televisions and refrigerators are of a vast number, and thus, IPv4 addresses have become insufficient for such devices to access the Internet. Accordingly, IPv6 technology was proposed to solve the insufficient IP addresses and complement the inefficiency of IPv4 so as to improve Internet performance.
IPv6 has a 128 bit address system. Thus, this address system has many more IP addresses than the 32 bit address system of IPv4. The address system increased to 128 bits also increases the contents of a routing table, which are essential for path determination at a router. This can increase the time consumed to find a suitable route. However, since the IPv6 address system has many more layers than the IPv4 address system, the increased time consumed to find a suitable route from the routing table is small.
Since IPv6 has improved performance over IPv4, IPv6 can solve Internet performance related problem owing to the rapid increase in Internet traffic and the generalization of multimedia traffic.
The IP address allocated to a host or node is composed of network identifier and host identifier. The network identifier is information for uniquely indicating a network to which the host is connected, and the host identifier is information for uniquely identifying the host in the corresponding network. The host allocated with the IP address generates a socket address by using the IP address and port number of a transmission layer, and establishes a connection to another host by using such socket information.
Therefore, once one host or host 1 has established a connection with another host or host 2, a constant IP address should be fixedly maintained to the host while the connection is established.
However, if one host connected to another host moves to another network, the network identifier should be changed, and the IP address allocated to the host must also be changed. Changing the IP address means changing the socket address, terminating all previously established connections, and thus, the host disadvantageously has to again attempt a connection.
In order to solve the problem of connection termination occurring when a host changes a network as above, the Internet Engineering Task Force (IETF) proposes a Mobile IPv6 (hereinafter referred to as 'MIPv6') protocol. The MIPv6 protocol proposes a method for enabling a Mobile Node (hereinafter referred to as 'MN') to continuously maintain previously-established connections even though the MN changes its location. That is, the MIPv6 protocol defines a mechanism by which even though the MN, which has connected to the Internet with has established connection to a Correspondent Node (hereinafter referred to as 'CN'), changes its Access Point (AP), the MN can maintain a connection to the CN.
However, when an MN moves from an MIPv6 network to a new network, a predetermined time is consumed until the MN is provided with Internet access service from the new network. Such a time is referred to as hand-over latency, which includes a time period until recognizing that the MN has moved to the new network, a time period until composing a new address from the new network and a time period necessary for registering the composed new address.
Accordingly, when the MN has moved from the MIPV6 network, any packet sent during such hand-over latency is transmitted to the previous address, which the MN has accessed before hand-over, and thus the packet is lost. Thus, packet loss increases in proportion to hand-over latency.
In order to solve such problems and reduce hand-over latency, Hierarchical MIPv6 (hereinafter referred to as 'HMIPv6') and Fast hand-over for MIPv6 (hereinafter referred to as 'FMIPv6') have been proposed.
HMIPv6 defines a router having new functions so-called Mobile Anchor Point (MAP), in which a set of ARs having same MAP information is referred to as a MAP domain. When the MN moves within the MAP domain, address change is reported merely to the MAP to reduce binding update time and resultantly reducing hand-over latency.
When HMIPv6 is used, additional registration procedures can be omitted at hand-over in the same MAP domain. Thus, it is possible to reduce hand-over latency at hand-over in the same MAP domain. However, event this process cannot completely eliminate hand-over latency. That is, when the MN moves, hand-over latency occurs, so that the packets are still discarded. Thus, problems of packet loss still take place even in the HMIPv6 network.
As another solution to reduce hand-over latency, there is FMIPv6. FMIPv6 uses a system configuration of an MIPv6 network as is. FMIPv6 can previously process information before the movement of the MN to a new network in order to reduce hand-over latency as well as minimize packet loss.
However, if it takes a long time for the MN to move or if a binding update time is delayed so that a number of packets are buffered, then some of the packets are delivered to the MN before all of the buffered packets are delivered to the MN.
This can cause problems in that the packets are delivered to the MN in the wrong order. This wrong order of the packets can remarkably degrade the performance of an application program. When the packets are received in the wrong order, a receiving side of the packets generates an acknowledgment signal requesting packets in the correct order. This as a result causes a duplicated acknowledgment, and when a transmitting TCP receives 3 or more duplicated acknowledgments, the transmitting TCP promptly changes into a retransmission and recovery state. In this state, the transmitting TCP retransmits its own traffic and reduces the size of a congestion window. The reduced congestion window size also degrades the transmitting TCP performance.
Also, in case of UDP based multimedia traffic, packet loss or packet disordering considerably degrades quality.
Therefore, where the MN moves to a new network, a mechanism capable of preventing not only packet loss but also packet disordering is essential.

Traffic exchanging method for mobile node in mobile internet protocol version 6 (MIPv6) network


A speaker includes a sound source, a rod-like member whose base end is in contact with the sound source, and a pair of flexible wing members whose ends are attached to the tip of the rod shape member, and whose other ends are free.

In a conventional speaker, a sound propagates in form of a dilatational wave (a sound wave/longitudinal wave), thereby stimulating human's hearing sense. A speaker which is different from such a conventional speaker is disclosed in Japanese Laid Open Patent Nos. 2000-350285, 2006-207108, and 2006-197562.
Japanese Laid Open Patent No. 2000-350285 discloses a speaker having a diaphragm, a support member which supports the diaphragm in a state where internal stress is produced therein, and a sound source connected with the support member.
Japanese Laid Open Patent No. 2006-207108 discloses a receiver, a piezoelectric device which vibrates based on an audio signal received by the receiver, and a helmet with a speaker to which the piezoelectric device is attached. Moreover, a sheet-like speaker to which the piezoelectric device is brought into close contact with a flexible sheet is disclosed.
Japanese Laid Open Patent No. 2006-197562 discloses a speaker having a piezoelectric device which vibrates based on an input signal, and a wave motion radiation unit which is brought into close contact with an oscillating face of the piezoelectric device.
In Japanese Laid Open Patent Nos. 2006-197562 and 2006-207108, physical characteristics of such a speaker, which are different from those of the conventional speaker are described as set forth below.
That is, the speaker uses the wave motion property of sound. Since the sound from the speaker may propagate in the air as a wave motion, energy loss and its attenuation rate are low, as compared with the conventional speaker. The sound quality and a propagation property thereof are excellent.
In addition, from another point of view, the sound from the speaker described above may be deemed to propagate in the air as particles. However, the mechanism of such a physical phenomenon of the speaker is not necessarily clearly explained.


An isolated or purified polypeptide having xyloglucanase activity which is obtained from a strain of the genus Malbranchea and has xyloglucanase activity in the pH range 4-11, measured at 50xc2x0 C.; and/or a molecular mass of 25xc2x110 kDa, as determined by SDS-PAGE; and/or an isoelectric point (pI) in the range 3-5; and/or an N-terminal sequence Ala-Asp-Phe-Cys-Gly-Gln-Xaa-Asp-Ser-Glu-Gln-Ser-Gly-Pro-Tyr-Ile-Val-Tyr-Asn-Asn-Leu is useful in industrial applications such as in laundry detergent compositions and for treatment of textiles.

The present invention relates to xyloglucanase enzymes which are endogeneous to a strain belonging to Malbranchea, especially enzymes exhibiting xyloglucanase activity in the pH range 4-11; to a method of producing such enzymes; and to use of such enzymes in the textile, detergent and cellulose fiber processing industries.
Xyloglucan is a major structural polysaccharide in the primary (growing) cell wall of plants. Structurally, xyloglucans consists of a cellulose-like beta-1,4-linked glucose backbone which is frequently substituted with various side chains. The xyloglucans of most dicotyledonous plants, some monocotyledons and gymnosperms are highly branched polysaccharides in which approx. 75% of the glucose residues in the backbone bear a glycosyl side chain at O-6. The glycosyl residue that is directly attached to the branched glucose residue is invariably alfa-D-xylose. Up to 50% of the side chains in the xyloglucans contain more than one residue due to the presence of beta-D-galactose or alfa-L-fucose-(1-2)-beta-D-galactose moieties at O-2 of the xylose residues (C. Ohsumi and T. Hayashi (1994) Plant and Cell Physiology 35:963-967; G. J. McDougall and S. C. Fry (1994) Journal of Plant Physiology 143:591-595; J. L. Acebes et al. (1993) Phytochemistry 33:1343-1345). On acid hydrolysis, the xyloglucan extracted from cotton fibers yielded glucose, xylose, galactose and fucose in the ratio of 50:29:12:7 (Hayashi et al., 1988).
Xyloglucans produced by solanaceous plants are unusual in that typical only 40% of the beta-1,4-linked glucose residues bear a glycosyl side chain at O-6. Furthermore, up to 60% of the xylose residues are substituted at O-2 with alfa-L-arabinose residues and some solanaceous plants, such as potato, also have xyloglucans with beta-D-galactose substituents at O-2 of some of the xylose residues (York et al (1996)).
Xyloglucan is believed to function in the primary wall of plants by crosslinking cellulose-microfibrils, forming a cellulose-xyloglucan network. This network is considered necessary for the structural integrity of primary cell-walls (Carpita et al., 1993). Another important function of xyloglucan is to act as a repository for xyloglucan subunit oligo-saccharides that are physiologically active regulators of plant cell growth. Xyloglucan subunits may also modulate the action of a xyloglucan endotransglycosylase (XET), a cell-wall associated enzyme that has been hypothesized to play a role in the elongation of plant cell walls. Therefore xyloglucan might play an important role in wall loosening and consequently cell expansion (Fry et al., 1992).
The seeds of many dicotyledonous species contain xyloglucan as the major polysaccharide storage reserve. This type of xyloglucan, which is localized in massive thickenings on the inside of the seed cotyledon cell wall, is composed mainly of glucose, xylose and galactose (Rose et al., 1996).
Seeds of the tamarind tree Tamarindus indica became a commercial source of gum in 1943 when the gum was found useful as a paper and textile size. Sizing of jute and cotton with tamarind xyloglucan has been extensively practiced in Asia owing to the low cost of the gum and to its excellent properties. Food applications of tamarind xyloglucan include use in confections, jams and jellies and as a stabilizer in ice cream and mayonnaise (Whistler et al., 1993).
Xyloglucanase activity is not included in the classification of enzymes provided by the Enzyme Nomenclature (1992). Hitherto, this enzymatic activity has simply been classified as glucanase activity and has often been believed to be identical to cellulolytic activity (EC 184.108.40.206), i.e. activity against xcex2-1,4-glycosidic linkages in cellulose or cellulose derivative substrates, or at least to be a side activity in enzymes having cellulolytic activity. However, a true xyloglucanase is a true xyloglucan specific enzyme capable of catalyzing the solubilisation of xyloglucan to xyloglucan oligosaccharides but which does not exhibit substantial cellulolytic activity, e.g. activity against the conventionally used cellulose-like substrates CMC (carboxymethylcellulose), HE cellulose and Avicel (microcrystalline cellulose). A xyloglucanase cleaves the beta-1,4-glycosidic linkages in the backbone of xyloglucan.
Xyloglucanase activity is described by Vincken et al. (1997) who characterizes three different endoglucanases from Trichoderma viride (similar to T. reesei) which all have high activity against cellulose or CMC and show that the EndoI (which is indeed belonging to family 5 of glycosyl hydrolases, see Henrissat, B. et al. (1991, 1993)) has essentially no (i.e. very little) activity against xyloglucan, and that EndoV (belonging to the family 7 of glycosyl hydrolases) and EndoIV (belonging to the family 12 of glycosyl hydrolases) both have activity against xyloglucan and CMC, respectively, of the same order of magnitude.
International Patent Publication WO 94/14953 discloses a xyloglucanase (EG II) cloned from the fungus Aspergillus aculeatus.
International Patent Publication WO 98/38288 discloses amino acid sequences of xyloglucanases from Tiarosporella phaseolina and Dichotomocladium hesseltinei, respectively.
International Patent Publication WO 98/50513 discloses laundry and cleaning compositions containing xyloglucanase enzymes.
International Patent Publication WO 99/02663 discloses xyloglucanases cloned from Bacillus licheniformis and Bacillus agaradhaerens.
Since many important processes, both industrial processes and domestic processes using industrially produced agents, are operating at a high pH in the alkaline range. Accordingly, there is a need for a true xyloglucanase enzyme with a high xyloglucanase activity at an alkaline pH.
The inventors have now found enzymes having substantial xyloglucanase activity at high pH in the alkaline range, such enzymes being obtained from or endogenous to a strain belonging to the fungal genus Malbranchea.
Accordingly, the present invention relates to an isolated or purified xyloglucanase enzyme obtained from a strain belonging to the genus Malbranchea, preferably to a strain belonging to a species selected from the group consisting of Malbranchea cinnamomea (and the three synonyms Malbranchea sulfurea, Malbranchea pulchella var. sulfurea and Thermoidium sulfureum), Malbranchea graminicola, Malbranchea pulchella, Malbranchea filamentosa, Malbranchea gypsea, Malbranchea albolutea, Malbranchea arcuata, Malbranchea aurantiaca, Malbranchea bolognesii-chiurcoi, Malbranchea chrysosporioidea, Malbranchea circinata, Malbranchea flava, Malbranchea flavorosea, Malbranchea flocciformis, Malbranchea fulva, Malbranchea kambayashii, Malbranchea multicolor, Malbranchea sclerotica, Malbranchea setosa and Malbranchea dendritica, which enzyme exhibits xyloglucanase activity and no activity on cellulose or cellulose derivative substrates. In a preferred embodiment of the invention, the xyloglucanase has an apparent molecular weight of 25xc2x110 kDa, a pI between 3 and 5 and exhibits xyloglucanase activity the pH range 4-11, measured at 50xc2x0 C.
In a further aspect, the present invention provides a xyloglucanase cloned from a strain belonging to Malbranchea, i.e. a xyloglucanase selected from one of (a) a polypeptide comprising a fragment encoded by the DNA sequence of positions 141-806 of SEQ ID NO:1; (b) a polypeptide produced by culturing a cell comprising the sequence of SEQ ID NO:1 under conditions wherein the DNA sequence is expressed; and (c) a xyloglucanase enzyme having a sequence of at least 80% identity to positions 1-222 of SEQ ID NO:1 when identity is determined by GAP provided in the GCG program package verion 10.0 using a GAP creation penalty of 8 and GAP extension penalty of 2.
In another aspect, the present invention provides an isolated or purified polypeptide having xyloglucanase activity which is obtained from a strain of the genus Malbranchea and has
i) xyloglucanase activity in the pH range 4-11, measured at 50xc2x0 C.;
ii) a molecular mass of 25xc2x110 kDa, as determined by SDS-PAGE;
iii) an isoelectric point (pI) in the range 3-5; and/or
iv) the N-terminal sequence Ala-Asp-Phe-Cys-Gly-Gln-Trp-Asp-Ser-Glu-Gln-Ser-Gly-Pro-Tyr-Ile-Val-Tyr-Asn-Asn-Leu (SEQ ID NO: 2).
The invention further provides an isolated xyloglucanase enzyme which is (i) free from homologous impurities, and (ii). produced by culturing a cell comprising the DNA sequence of positions 141-806 of SEQ ID NO:1.
The novel enzyme of the present invention is useful for the treatment of cellulosic material, especially cellulose-containing fiber, yarn, woven or non-woven fabric. The treatment can be carried out during the processing of cellulosic material into a material ready for garment manufacture or fabric manufacture, e.g. in the desizing or scouring step; or during industrial or household laundering of such fabric or garment.
Accordingly, in further aspects the present invention relates to a detergent composition comprising a xyloglucanase which is endogeneous to a strain belonging to the fungal genus Malbranchea, in particular belonging to the fungal species Malbranchea cinnomomea, and exhibits substantial activity in the alkaline pH range; and to use of the enzyme of the invention for the treatment of cellulose-containing fibers, yarn, woven or non-woven fabric.
The present invention has now made it possible to use a truly enzymatic scouring process in the preparation of cellulosic material e.g. for proper response in subsequent dyeing operations. Further, it is contemplated that detergent compositions comprising the novel enzyme are capable of removing or bleaching certain soils or stains present on laundry, especially soils and spots resulting from xyloglucan-containing food, plants, and the like. It is also contemplated that treatment with detergent compositions comprising the novel enzyme can prevent binding of certain soils to the xyloglucan left on the cellulosic material.


A spring winding device, a counterbalancing force adjustment device for a counterbalancing mechanism, and a method of adjusting an amount of force stored in a spring of a counterbalancing mechanism are provided. The spring winding device includes a support bracket, a worm gear, and a drive gear. The worm gear is rotatably coupled to the support bracket and includes a mount portion for coupling a first end cone thereto. The drive gear is rotatably disposed adjacent the support bracket and is drivingly engaged with the worm gear. A rotation of the drive gear causes the worm gear to rotate within the support bracket. The spring winding device does not require pretensioning using winding rods, maintains rigidity and alignment when a counterbalancing force is applied, and decreases a cost and a complexity of the counterbalancing mechanism.

Conventionally, a torsion spring counterbalancing mechanism may be used with an overhead door to counterbalance a weight of the overhead door when moving the overhead door during between an open position and a closed position. When the torsion spring counterbalancing mechanism is installed, one or more springs forming a portion of the torsion spring counterbalancing mechanism need to be pretensioned with an amount of counterbalancing force. Further, following initial installation, adjustment of the amount of counterbalancing force may be necessary to repair or replace the torsion spring counterbalancing mechanism.
A conventional method used to adjust the amount of counterbalancing force in one or more springs forming a portion of the torsion spring counterbalancing mechanism may be dangerous. Winding rods are typically inserted into a spring end cone, a rotational force is applied to the one or more springs, the spring end cone is disengaged from a torsion shaft, and the amount of counterbalancing force is one of increased and decreased. When a first winding rod is inserted in the spring end cone, the rotational force may be applied to the one or more springs. Using a second winding rod and an iterative process, the one or more springs may be wound or unwound. Such a process may be dangerous, as the winding rod will rotate quickly when the one or more springs are pretensioned and the winding bar is unrestrained.
To reduce such a danger, it is known in the prior art to employ a spring winder having a worm drive gear engaged with a worm wheel to adjust the amount of counterbalancing force. The worm wheel is fitted about a center portion of the torsion shaft and the worn drive gear is rotated to adjust the amount of counterbalancing force in the one or more springs. However, when the one or more springs are pretensionsed, the worm wheel may tilt or move along its axis as it resists the counterbalancing force. When the worn wheel tilts or moves along its axis, the worn drive gear may become disengaged or misaligned, rendering such a spring winder inoperable.
It is also known in the prior art to locate the spring winder having the worm drive gear engaged with the worm wheel at an end of the torsion shaft to militate against movement of the worm wheel. In such an arrangement a separate spring winder is employed for each spring, and the spring winder is subject to a thrust force of the spring. Balancing the thrust force of the spring may extend a service life of the spring significantly. Further, in such an arrangement, non-conventional cable drums are employed to house a portion of the spring winder. The spring winder having the worm wheel at an end of the torsion shaft increases a cost and a complexity of the counterbalancing mechanism while decreasing a service life of the one or more springs.
It would be advantageous to develop a spring winding device that does not require pretensioning using winding rods, maintains rigidity and alignment when a counterbalancing force is applied, and decreases a cost and a complexity of a counterbalancing mechanism the spring winding device is incorporated in.

Spring winding device for use with overhead doors


Techniques relating to buffer circuits. In one embodiment, a circuit includes a first transistor configured as a source follower and a feed-forward path coupled to the gate terminal of the first transistor and the drain terminal of the first transistor. In this embodiment, the feed-forward path includes circuitry configured to decouple the feed-forward path from a DC component of an input signal to the gate terminal of the first transistor. In this embodiment, the circuitry is configured to reduce a drain-source voltage of the first transistor based on the input signal. In some embodiment, the feed-forward path includes a second transistor configured as a source follower and the source terminal of the second transistor is coupled to the drain terminal of the first transistor. In various embodiments, reducing the drain-source voltage may improve linearity of the first transistor.

1. Technical Field
This disclosure relates to analog circuits and more particularly to a highly linear buffer circuit.
2. Description of the Related Art
Buffer circuits are often used to transfer a signal from a circuit with a given impedance level to another circuit with a different impedance level. For example, when transmitting radio frequency (RF) signals using a cable (e.g., for cable television), a buffer may be used between the circuitry generating the signal and the cable itself. Cable often has low impedance (e.g., low resistance and/or large capacitance). Buffer/driver circuits may or may not amplify an input signal. Typically, a linear relationship between an input signal to a buffer and an output signal from the buffer is preferable for preserving signal quality.


Provided is a paddle processor and a method for processing material within the paddle processor. In one example, the paddle processor may include a trough comprising an inlet to receive a feed of material and an outlet for exiting the material after processing, rotational paddles disposed in the trough and configured to rotate about each other to move the material from the inlet to the outlet, an overflow weir disposed in association with the outlet and having a dynamically adjustable height for controlling a rate at which the material exits the trough, and a control system configured to dynamically adjust the height of the overflow weir and/or other dryer parameters based on a temperature of the material within the trough.

A paddle dryer (also referred to as a paddle processor, etc.) is an efficient, mechanically agitated, indirect heat transfer device that can add or remove heat from a process mass in the form of a liquid, a paste, a cake, a granule, or the like. The paddle dryer may be used for indirect drying, heating, cooling, pasteurization, crystallizing, reacting of material, and the like. A paddle dryer may include one or more shafts such as a single shaft, dual counter-rotating shafts, etc. with unique intermeshing wedge shape paddles, and the like, which produce intimate mixing and optimize heat transfer to the material held within. The paddles may be hollow allowing for optimal heat transfer. For example, steam, oil, thermal fluid, water, glycol, or the like, may be introduced into the paddles to cause the paddles to heat up or chill down. The paddles in turn contact the material thereby isolating the heating/cooling liquid/gas from the process mass.
As one example, a thickened sludge (i.e., dewatered manure) may be fed into the paddle dryer in the form of a liquid, paste, etc., and converted into a granular powder that can be used as fertilizer, etc. As the sludge moves through the dryer (e.g., over the course of hours, etc.) the material slowly turns from a paste to a dry granule. One of the difficulties with paddle dryers is the ability to control the temperature of the product within the dryer. Typically, if the material (e.g., sludge, etc.) coming out of the dryer is too dry, an operator will lower the temperature of the paddle dryer to compensate. Likewise, if the material coming out of the paddle dryer is too wet the operator will raise the temperature of the paddle dryer to compensate.
However, raising/lowering the temperature of the paddle dryer raises/lowers the temperature throughout the entire paddle dryer (e.g., paddles) including the front end where the material is being fed to the back-end where the material is coming out. While the changes in temperature may quickly address the issue at the backend having the material which is too wet/dry, it may also cause reverse negative effects on new material entering at the front of end the paddle dryer (i.e., causing it to turn out too dry or too wet) during processing. As a result, the process will ping-pong back and forth creating a material that is either too dry or too wet, requiring an operator to continually raise/lower the dryer to accommodate changes to the consistency of the material being output.
Furthermore, as material dries in the backend of the dryer it loses a significant amount of water content to the point where the surface moisture of the product has such little water content (e.g., moisture content of 10% or less) that it needs a greater temperature than 212° to further dry the material. As a result, the material within the backend of the paddle dryer has to be heated to a higher temperature (e.g., 240°, etc.) to continue the drying process. Here, the outside of the material particles may be 240° but the inside of the particle is just reaching 212° because of transient heat conduction inside the particle. As a result, the temperature often has to be driven up a significant amount to accommodate the particles with less water content.
Besides the transient heat transfer component there is also a diffusion component that takes places. As noted, there is a critical moisture content (e.g., moisture content of 10% or less) where the surface moisture of a particle is depleted leaving behind internal bound or interstitial moisture. At this point two things happen to evaporate the remaining moisture. First, the surface of the particle heats up and this heat is then conducted inside the particle. This heat then evaporates the water inside the particle which then migrates out of the particle. At the same time, water inside the particle diffuses outward towards the particle surface. Once it reaches the surface (or perhaps on it's way to the surface) it evaporates. In the time it takes for the water to diffuse to the surface, the surface of the particle heats up. The result is that particles often heat up above 212° F. as you remove the last 10% or so of moisture.
Accordingly, what is needed is an improved mechanism for managing temperature of material being processed by a paddle dryer that does not rely on raising/lowering the temperature of the paddle dryer or making manual/static adjustments by the dryer operator.

Dynamic state configuration for paddle processor


A reproduction method for reproducing BCA data for optical discs using the defect signal. The reproduction method for reproducing BCA data includes the steps of: generating a defect signal as a BCA signal by detecting an RF signal of the BCA; generating a BCA data bit stream by sampling the BCA signal according to a sampling clock; and decoding the BCA data bit stream to generate BCA data. Because the defect signal is utilized as the BCA signal of the invention, no additional BCA signal extracting device is needed.

1. Field of the Invention
The invention relates to a BCA data reproduction method and apparatus for optical discs, in which a defect signal generated from a defect detector in a signal reproduction unit is used as a BCA (Burst Cutting Area) signal.
2. Description of the Related Art
Typically, digital video discs or digital versatile discs (hereinafter referred to as DVDs) include DVD-ROM (Read Only Memory), DVD-R (Recordable), and DVD-RAM (Random Access Memory). In the development of DVD-ROM disk, it has been suggested to provide a BCA (Burst Cutting Area) for the purpose of providing information for identifying each of the DVD-ROM discs. A BCA code (signal) is recorded on the aforementioned DVD-ROM disc, after a predetermined video data or the like is recorded, by partially removing with a laser beam an aluminum film which has been deposited as a reflection film. That is, a BCA code is formed by removing an aluminum film of an area not affecting reproduction of a video data, audio data, or computer data which has been recorded as a pit signal on the disc. More specifically, the BCA code is recorded so as to be overwritten on a pit string of dummy data recorded on an area located along the inner circumference of the disc.
As shown in FIG. 1, the BCA 11 is recorded as bar-code stripes in the circumferential direction of the optical disc 10, and each stripe has a length of about 1 mm between 22.3 (+0/−0.4) mm to 23.50±0.5 mm from the center of the center hole of the disc. The BCA data writing method adopts a laser beam to remove a part of the area of the reflection film in a radiation direction. In general, the BCA data is recorded by way of a RZ (return to zero) modulation method and read out by an optical pickup serving for reproducing video data or audio data recorded on the optical disk. Since a dummy pit string has already existed in the original BCA, when the optical pickup head reads the BCA data, the obtained RF (radio frequency) signal includes a BCA stripe signal and a high-frequency pit string signal. FIG. 2 shows the RF signal and the BCA signal for the BCA, wherein FIG. 2(A) shows the RF signal and FIG. 2(B) shows the BCA signal.
FIG. 3 is a block diagram showing a conventional BCA signal reproduction apparatus. In the conventional BCA signal reproduction method, a BCA signal reproduction apparatus is used to extract the desired BCA information from the RF signal. As shown in FIG. 3, the BCA signal reproduction apparatus utilizes a peak detector 31 to detect the peak value of the RF signal. Since the RF signal carries the high-frequency pit signal, a low-pass filter (LPF) 32 has to be used to filter out the high-frequency component in the RF signal. Furthermore, a slice signal generator 33 is utilized to generate a slice signal corresponding to the RF signal. Then, two processed signals are compared in a comparator 34, which generates a BCA signal accordingly. However, since the RF signal is subjected to BCA's mirror modulation, thus causing the phenomenon of DC wandering, and the high-frequency component in the RF signal may not be completely filtered out easily, a correct BCA signal cannot be extracted in the conventional method.
Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.


A cell phone system (10) for enabling and disabling a vehicle (12) includes a cell phone (20) and a receiving receptacle (22) secured within the vehicle (12) that is configured so that the cell phone (20) cannot transmit signals whenever the cell phone (20) is secured within the receiving receptacle (22). A vehicle enabling mechanism (44) is secured within the receiving receptacle (22) and is also secured in communication with an engine (50) of the vehicle (12) so that placement of the cell phone (20) within the receiving receptacle (22) activates the vehicle enabling mechanism (44) to put the vehicle (12) in an enabled mode, and so that removal of the cell phone (20) from the receiving receptacle (22) deactivates the vehicle enabling mechanism (44) to put the vehicle (12) in a disabled mode.

Cell phones are increasingly common especially amongst adolescents and teenagers, and use of cell phones by young and novice operators of vehicles has become a grave hazard on roadways. Initially, it was thought that use of an operator's hand or hands during operation of the cell phone was the primary problem resulting in inattentive drivers. Therefore, many efforts focused upon development of "hands-free" cell phones, either integral with the vehicle, or by way of dashboard mounting of cell phones with removable headsets, or "BLUETOOTH" brand ear pieces, etc. However, more recent studies have concluded that the most distracting aspect of cell phone usage is a conversational interchange between the user and the person to whom the user is talking. Unlike a radio or musical sound system within a vehicle, which is exclusively one-way communication, cell phone usage is necessarily two-way communication that involves such a high level of mental activity that simultaneous careful operation of a vehicle frequently becomes a secondary concern.
More recently, cell phones have grown in technical complexity, involving "smart phones" that can access the internet for e-mail correspondence, and that include full mini-keyboards for "texting" messages, etc. Consequently, cell-phone based driver distractions have become an ever growing hazard. To minimize this potentially lethal hazard, many states have enacted laws severely restricting usage of cell phones while driving. Unfortunately, however, such laws are extremely difficult to enforce, especially at night when driving hazards are greatest because law enforcement officers are unable to see within vehicles.
This problem has been recognized and many efforts have been undertaken to eliminate usage of a cell phone by an operator of a vehicle. Such efforts however, typically require very costly and complex apparatus and systems and therefore have not experienced widespread acceptance. For example, a "Motion Disabled Cell Phone" is shown in U.S. Patent Application Publication No. US 2005/0255874 A1 by Stewart-Baxter et al. The Stewart-Baxter cell phone includes use of a "Global Positioning System" ("GPS") reader or an accelerometer integrated within a cell phone, and software within the cell phone to disable the cell phone when motion of the phone is detected by the GPS reader or accelerometer. Such a cell phone therefore, cannot be utilized in a moving vehicle. Another example is shown in U.S. Patent Application Publication No. US 2008/0268767 A1 to Brown et al., wherein an interference device and an antenna element secured within a vehicle produce a bare carrier wave or noise at sufficient power to interfere with operation of a cell phone within the vehicle. Both Stewart-Baxter et al. and Brown et al. require costly modifications to a cell phone and a vehicle, and both result in all cell phones within a vehicle being disabled.
Another example of an effort to restrict usage of cell phones in a vehicle is shown in U.S. Patent Application Publication No. US 2007/0270122 A1 to Ewell Jr. The Ewell Jr. disclosure also requires use of a location tracking unit that uses a GPS signal and a disabling circuit within a cell phone. The resulting system may be utilized to disable cell phones when they are within a restricted region, provided the cell phones include the disabling circuit. These disclosures indicate that complex and costly systems are available for selectively disabling cell phones to suit particular conditions. However, none have gained wide acceptance probably because they require substantial modification to cell phones, which result in the inability of the modified cell phone to be utilized whether the owner of the cell phone is operating the vehicle, or merely a passenger in the vehicle. Therefore such unpopular modified cell phones are simply not available.

Cell phone system for enabling and disabling a vehicle


A display device includes a display module extending in a first direction, a supporting portion disposed under the display module and which supports a part of the display module, a first driving part connected to a first end of the display module to roll and unroll the display module, a connecting portion connected to a second end of the display module, and a second driving part connected to the connecting portion to roll and unroll the connecting portion. The second driving part unrolls the connecting portion when the first driving part rolls the display module, and the second driving part rolls the connecting portion when the first driving part unrolls the display module.

The present disclosure herein relates to a display device, and more particularly, to a display device in which a display module is expanded or reduced.
In general, an electronic apparatus providing images to users, such as smartphones, digital cameras, laptop computers, navigation devices, and smart televisions, includes a display device for displaying images. The display device generates images to provide the images to users through a display screen.
Various types of display devices have been developed. For example, a flexible display device or the like that may be folded or rolled has been developed. The flexible display device capable of being deformed into various shapes may be easily portable and may improve the convenience of users.


The present invention relates to a method of preparing a novel water-soluble and self-doped polyaniline graft copolymer, wherein aniline was grafted onto a poly(styrenesulfonic acid-c-aminostyrene) backbone. The graft copolymer is useful for advanced applications such as electrode manufacture, EMI shielding, static electricity dissipation, metal anti-corrosion, electrochromic materials, sensors, functional film and marine-fouling prevention.

Polyaniline is one of the extensively studied intrinsic conducting polymers and shows electrical conductivity after proton-doping or oxidation. It had been well known that polyaniline can be prepared with easiness, high yield and low cost of synthesis and also shows very high conductivity with excellent environmental stability in a conducting form. (MacDiarmid, A. G. In Conjugated polymers and Related Materials, The Interconnection of Chemical and Electronic Structure; Salaneck, W. R.; Lundstrom, I.; Ranby, B., Eds.; Oxford University Press, 1993, PP 73–98)
Poyaniline can be used in the advanced application such as secondary battery, light emitting diode, electrochromic materials and sensor because of it's excellent electrical and electrochemical and optical properties. For these applications, polyaniline should be prepared in a film or processable form. Thus, development of water-soluble polymers becomes important when commercial applications are considered. However, few solution processes have been reported because conducting polymers based on polyaniline are not soluble in common solvent due to the π-π interaction between the rigid polyaniline backbone.
In the latest 10 years, processable polyaniline that is soluble in organic solvent or water was developed by virtue of the advance in the research on solution process. Base form of polyaniline (emeraldine base) can be processed in solvent such as strong Lewis-acid, like N-methylpyrrolidone (NMP) (Tzou, K. T. and Gregory, R. V. Synth. Met. 1995, 69, 109) or concentrated sulfuric acid (Andreatta, A., Cao, Y., Chiang, J. C., Heeder, A. J. and Smith, P. Synth. Met. 1988, 26, 383). More recently, Conducting forms of polyaniline can be processed in a polar or non-polar solvent by using the acidic dopant such as dodecylbenzene sulfonic acid or camphorsulfonic acid (Cao, Y., Smith, P. and Heeder, A. J. Synth. Met. 1992, 48, 91).
The method for the preparation of water-soluble polyaniline has been also developed. Several methods such as the introduction of alkyl sulfonic acid group onto the nitrogen atom in polyaniline (Bergeron, J. Y., Chevalier, J. W. and Dao, Le H. J. Chem. Soc., Chem. Commun. 1990, 180; Chen, S. A. and Hwang, G. W. J. Am. Chem. Soc. 1994, 116, 7939), or chemical or electrochemical polymerization of anline-N-alkyl sulfonate (Bergeron, J. Y., Chevalier, J. W. and Dao, Le H. J. Chem. Soc., Chem. Commun. 1990, 180; Chen, S. A. and Hwang, G. W. J. Am. Chem. Soc. 1994, 116, 7939) were reported to prepare water-soluble polyaniline. More recently, it has been reported that water-soluble polyanline was prepared by polymerization of di-phenyl-4-sulfonic acid (DeArmitt, C., Armes, C. P., Winter, J., Uribe, F. A., Gottesfeld, J. and Mombourquette, C. Polymer 1993, 34, 158) or copolymerization of O-amino benzyl alcohol and diphenyl-4-sulfonic acid (Nguyen, M. T. and Diaz, A. F. Macromolecules 1994, 27, 7003).
Another method for the preparation of water-soluble polyaniline was synthesis of PANIs in the presence of a water-soluble polymeric acid [M. Angelopoulos, N. Patel, J. M. Shaw, N. C. Labianca and S. A. Rishton, J, Vac. Sci. Technol. B11, 2794(1993); K. Shannon, and J. E. Fernadez, J. Chem. Soc. Chem. Commum., 643(1994)].
The water-soluble polyaniline prepared by above methods can't be extracted and purified from the reaction solution and by-product after synthesis. Residual product and reagent that remains unreacted in the solution is very difficult to separate from water. Thus, the dialysis was conducted to purify the resulted polyaniline, but it takes much time and there is a doubt on the degree of purity. The excess water also should be extracted for the preparation of desired concentration of water-soluble polyaniline aqueous solution.
On the other hand, the electrochemical properties such as reversible oxidation/reduction and the stability during the potential swap cycle is very important when film or coatings of the solution-processed polyaniline are used in electrochemical applications. The most important factor that determines such properties is the ionic conductivity of the film. The diffusion rate of ions has effects on the reversibility of oxidation/reduction and the length of life. It has been reported that cycles of oxidation/reduction in N-alkyl sulfonic acid substituted polyaniline were over 100,000 in the acidic condition (Kim, E. M., Lee, M. H., Moon, B. S., Lee, C. and Rhee, S. B. J. Electrochem. Soc., 1994, 141, L26), in which the above method isn't applicable to the secondary battery or electrochromic material.
Recently, it has been reported that when the copolymer of poly(styrenesulfonic acid) and oligo ethyleneglycol acrylate was used for the dopant of polyaniline, the electrical property was enhanced (H. Tsutsumi, S. Fukuzawa, M. Ishikawa, M. Morita, and Y. Matsuda, J. Electrochem. Soc., 142, L168(1995)). In this case, the electrical property was preserved even after the 40 cycles of charging and dis-charging, but the polymerization method is very difficult and the solution process wasn't possible because the prepared polyaniline film couldn't be dissolved in solvent.

Method of making novel water-soluble and self-doped polyaniline graft copolymers

Seoul National University Industry Foundation


Disclosed is a track-search control circuit for performing track-search of an optical disc stably even at the time of multi-speed reproduction of the optical disc. The track search control circuit comprises a circuit for detecting the light beam having traversed the track when the light beam moves in the radial direction of the optical disc and generating a normal direction on-track signal FVACLR at the time of being on the track and a normal direction off-track signal FVBCLR at the time of being off the track, a first measurement circuit that starts time measurement at the time of generating the normal direction on-track signal, a second measurement circuit that starts time measurement at the time of generating the normal direction off-track signal, circuits which detect the error between a moving velocity of the optical beam in the radial direction of the optical disc and a target velocity based on a measurement output by the first measurement circuit and a measurement output by the second measurement circuit, and a correction circuit for correcting the moving velocity of the optical beam in the radial direction based on the detected error signal.

The present invention relates to a track search control circuit for controlling track search of an optical disc and an optical disc drive equipped with a track search control device with the use of the track search control circuit, which are used, for example, for optical disc reproducing apparatuses such as a CD (Compact Disc) ROM drive for a computer system, a DVD (Digital Versatile Disc) drive, etc. and for optical disc recording/reproducing apparatuses for a CD-R, a CD-RW, a DVD-RAM, etc.
Conventionally, in optical disc systems for the DVD, the CD, etc., when the track search of the optical disc is performed, track traversing direction/frequency of a laser beam spot are detected using amplitude information of a tracking error signal and a readout signal at a time when the laser beam spot traverses the track, and the velocity control of the track search is performed.
That is, when the track search is performed, the track search control circuit is given the track search direction BWFW and the necessary number of tracks to be searched by a system controller, and generates track traversing information of the laser beam spot from a tracking error signal TE and a readout ripple signal RFRP. Then, acceleration/deceleration energy necessary for the track search is calculated from the track traversing information, the track search direction, and the number of tracks to be searched, and a signal indicative of the energy is added to an input of a tracking servo equalizer.
Now, along with the increase in a disc angular velocity in reproducing the optical disc in connection with the competition for reproduction speed of optical disc systems, the necessity of performing the track search under a condition of a large angular velocity of the disc has been arisen. However, in the case where the disc angular velocity is large, the variation of eccentric acceleration of the disc is large, and hence it is likely to be difficult to control the track search velocity effectively in the conventional track search method.
Hereafter, regarding this respect, a configuration of a conventional velocity error detection circuit for the track search control circuit will be described with reference to FIG. 11.
In the velocity error detection circuit of FIG. 11, a velocity error detection counter (FVCTR) 81 measures a semi-track interval. The velocity error detection counter FVCTR 81 is a 5-bit counter, whose count is incremented by a target velocity clock FVCK. Therefore, the target velocity clock counter (FVCTR) 81 can count thirty-two clocks (FVCKS) and when the counter reaches the full-count, a full count detection signal FULL-DET becomes logic "H". Further, when the velocity error detection counter (FVCTR) 81 counts the full count, a gate 83 for the target velocity clock FVCK is turned off using an inverted signal of the full count detection signal FULL-DET by the inverter circuit 82 in order that after the full count the full count value does not return to zero by the next target velocity clock FVCK.
On the other hand, a normal direction on-track/off-track signal FVCLR is a pulse generated at the normal direction on-tracking/off-tracking time, which clears the FVCTR 81. It should be noted that the "normal direction" means a case where a direction in which the lens of the pick-up mechanism is moved with regard to the track is the same as a track search direction given by a system controller.
A data latch signal FVLP is a pulse generated just before the generation of the normal direction on-track/off-track signal FVCLR. The data latch signal FVLP latches (the count value of the FVCTR−15)×(+1) or (the count value of the FVCTR−15)×(−1) in the TKIC (track search velocity control) register 85. Specifically, when the track search is to be performed in the outward direction, the BWFW signal from the system controller is goes to a logical low level, and in this time, (the count value of the FVCTR−15)×(+1) is latched by the TKIC register 85. On the other hand, when the track search is to be performed in the inward direction, the BWFW signal from the system controller goes to a logical high level, and in this time, (the count value of the FVCTR−15)×(−1) is latched by the TKIC register 85.
data including the count value (velocity measurement data) of the FVCTR 81 and the track search direction BWFW given by the system controller into a TKIC (track search velocity control) register 85. These normal direction on-track/off-track signal FVCLR and data latch signal FVLP are generated using the tracking error signal TE and the readout ripple signal RFRP.
Therefore, the velocity measurement result by the FVCTR 81 that counts up the target velocity clock FVCK is loaded into the TKIC register 85 at the data latch signal FVLP generated just before the generation of the track pulse, and is cleared by an inverted signal of the normal direction on-track/off-track signal FVCLR by an inverter circuit 84. In this case, a velocity measuring period of the FVCTR 81 is a half-track period, and acceleration/deceleration data stored in the TKIC register 85 is outputted in a half-track period next to the velocity measuring half-track period.
FIG. 12 is a characteristic diagram showing the relation between the track search velocity error and the number of the FVCK counts of the velocity error detection counter (FVCTR) 81 of FIG. 11.
FIG. 13 is a characteristic diagram showing the relationship between the FVCTR value detected as the velocity error and the value stored in the TKIC register 85 in the outward direction search, i.e., BWFW="L".
FIG. 14 is a characteristic diagram showing the relationship between the FVCTR value detected as the velocity error and the value stored in the TKIC register 85 in the inward direction search, i.e., BWFW="H".
FIG. 15 is a waveform chart showing output timing for a velocity error detection result in the velocity error detection circuit of FIG. 11 in a case where a track search in the outward direction is taken as an example.
In FIGS. 11 and 15, the target velocity clock FVCK is a clock having a frequency sixteen times that of the actual target velocity (half-track traversing target frequency). Accordingly, if the FVCTR 81 counted sixteen clocks until the velocity measurement result of the FVCTR 81 is latched in the TKIC register 85 at the data latch signal FVLP, it is the case where the actual velocity is equal to the target velocity (i.e. the velocity error being zero), the value zero ("0") is stored in the TKIC register 85.
Moreover, if the FVCTR 81 counted less than sixteen clocks until the velocity measurement result of the FVCTR 81 is latched in the TKIC register 85 at the data latch signal FVLP, it is the case where the actual velocity is higher than the target velocity, and a negative value in the outward direction search or a positive value in the inward direction search is stored in the TKIC register 85.
On the contrary, if the FVCTR 81 counted more than sixteen clocks until the velocity measurement result of the FVCTR 81 is latched in the TKIC register 85 at the data latch signal FVLP, it is the case where the actual velocity lower than the target velocity, and a positive value in the outward direction search or a negative value in the inward direction search is stored in the TKIC register 85.
In this way, error data between the target velocity and the actual track traversing velocity is modified by the track search direction signal BWFW and stored in the TKIC register 85, which becomes an input of addition of the tracking servo equalizer to effect the addition of a signal indicative of acceleration/deceleration energy in a tracking direction.
The velocity control method for the track search mentioned above referring to FIGS. 11 to 15 has an advantage that the track search velocity can be controlled accurately based on the measured velocity error (in multiple values). However, as will be mentioned below, it is difficult to perform the track search in the optical disc system for the DVD, the CD, etc. stably when the disc is reproduced at a multi-speed, because the timing of outputting the velocity measurement result stored in the TKIC register 85 is always in a next half-track period next to the period (half-track) when the velocity measurement was performed and because there may exist the eccentricity of the axis of rotation of the optical disc.
That is, generally in the case of a removable disc, when the disc is manufactured, the center of the disc made in a donut-shape is not necessarily in the center of a track formed in a spiral manner from which the signal is read. Moreover, the center of a track formed in a spiral manner is not necessarily in the axis of a disc motor, which results from improper placement of the disc when the disc is loaded (clamped). Furthermore, in manufacturing a disc drive, it is probable that the rotor axis of the disc motor for rotating the disc is not in the actual axis of rotation. Moreover, the rotor axis of the disc motor may have inclination to the actual axis of rotation.
The effect of such eccentricity of the disc rotation on the track search will be considered. When the track search is performed in an ideal condition without the eccentricity and if an objective lens housed in the pickup is moved at a constant velocity toward the inward direction/outward direction of the disc with respect to a frame fixing the mechanism, the relative velocity between the track and the objective lens becomes also constant. However, when the track search is performed under a condition with the existence of the eccentricity, if the objective lens is moved at a constant velocity with respect to the frame, the relative velocity between the track and the objective lens is modulated by the eccentric acceleration.
Therefore, in order to keep the relative velocity between the track and the objective lens constant or in a target velocity, it is necessary to alter the acceleration/deceleration energy that is given to a tracking coil (a drive coil of a pickup sending motor) in response to this change of the eccentric acceleration.
In this case, in the velocity control method as described above, the velocity measurement is performed for every half-track period by counting the target velocity clock FVCK and this count data is used as the track search velocity error data (acceleration/deceleration data). However, regarding the velocity measurement, the velocity measurement result for previous half-track period is used and the acceleration/deceleration data is outputted in a half-track period next to the velocity measuring half-track period, and hence this method may arise a problem.
The reason for this is that, since the variation of the eccentric acceleration is large in the multi-speed reproduction, the relative velocity between the track and the lens for the half-track period when the track search velocity is measured may differ largely from that for a half-track period when the acceleration/deceleration data is actually outputted, which results from the modulation due to the eccentricity.
That is, in an example shown in FIG. 15, at a time when the count value of the FVCTR 81 reaches C5, the track search control circuit is going to operate in such a way that almost maximum acceleration energy in the outward direction is made to be outputted, however in the next half-track period when the acceleration/deceleration data for outputting this acceleration energy is actually outputted, the track search velocity has already become approximately close to the target velocity.
The worst case is a case where the track search velocity is too high compared to the target velocity at the time of the detection of the track velocity, and the track search velocity, namely the relative velocity between the track and the objective lens, is controlled so as to become lower because of the erroneous measurement of the track search velocity resulted from the modulation due to the eccentricity in the next half-track period when the acceleration/deceleration data for causing the deceleration energy to output is actually outputted. In this case, although the track search velocity is low, the deceleration energy is to be further applied. However, since the acceleration/deceleration data is not renewed until the light beam traverses the track, there is likely to occur a situation where the deceleration energy term is kept on to be applied. In this case, the acceleration/deceleration control gets into an oscillation state and it may be difficult that the track search is stably performed.

Track search control circuit and optical disc drive