Abstract: Respective regenerative signals from magnetic heads 1A, 1B are combined into one system through a changeover switch 9. After the reproducing characteristic is compensated by using a filter 4 serving as an equalizer, that combined signal is decoded at a decoder 5. An adaptive control unit 7 adjusts (modifies) the characteristic of the filter 4 so that it becomes optimum on the basis of a decode error (residual) at the decoder 5 and an input to the filter 4. The adaptive control unit 7 carries out an adaptive processing in a time divisional manner for every regenerative signal of respective magnetic heads 1A, 1B to send filter coefficients for the respective magnetic heads 1A, 1B to the filter 4. Thus, since the adaptive processing is carried out in a time divisional manner by the filter 4 and the adaptive control unit 7, the circuit scale can be reduced, resulting in low cost.

Abstract: In a magnetic head driving circuit, switching devices are turned on/off in response to a recording signal, thereby inverting a drive current to be applied from direct current power sources to a magnetic head coil. Switching devices to be switched in connection with on/off of the switching devices are connected in parallel with dummy loads connected to the direct current power sources in series. In response to the switching of the switching devices, the magnetic head coil and the dummy load alternately function as a load of each auxiliary coil. Impedances of the dummy loads are set to be equal to the impedance of the magnetic head coil, thereby making the total load of each of the auxiliary coils fixed at any time. Since a balance can be established between a value of a drive current in one direction and that of a drive current in the opposite direction, it is possible to reduce jitter of a recording mark and enable the drive current to suddenly rise and fall.

Abstract: A method for detecting defects by detecting defects a magneto-optic property of a magneto-optic recording medium. A signal with constant frequency is recorded on a recording layer of the magneto-optic recording medium, and positive and negative side waveforms of the reproduced constant frequency signal obtained through play of the recording medium are integrated separately. The level of each of these integrated values and a reference level are compared, and a level drop of the peak value is detected.

Abstract: A read/write circuit for a disk drive system with a two-terminal magnetic head, having an adjustable damping resistor across the magnetic head. A switch network connects across the magnetic head and controls a resistor network to obtain an optimum level of impedance across the magnetic head in both the read mode and the write mode. The circuit provides a lower and well-defined impedance across the magnetic head in the write mode for all operating voltages across the head. A clamp circuit operates to prevent the write current source from saturating to improve current switching speed in the write mode.

Abstract: A method and device for storing data comprises a non-volatile memory for storing digital data words and a photoelectric transducer receptive of light energy applied thereto for producing an electric signal. The device is responsive to the electric signal for reading the stored digital data words out of the memory and for displaying the stored digital data words read out of the memory.

Abstract: A system for recording and reproducing data including user data on a magnetic tape having a number of partitions in which recording can be performed, the tape having at least one system zone in which user data is not recorded, the system having a table of data located near the beginning of the tape and near each system zone with the table including data identifying the physical location of the system zones and partitions and other sections of the tape.

Abstract: At least one of an error detection code for detecting an error in information to be recorded and an error correction code for correcting the error in the information is added to the information, and the information with at least one of the error detection code and the error correction code added thereto is recorded in a magnetic recording section provided in a photographic film. The information recorded in the magnetic recording section of the photographic film is read, and at least one of the detection of an information-reading failure and the correction of the error in the information is effected on the basis of at least one of the error detection code and the error correction code added to the information which has been read.

Abstract: A class IV partial response, maximum likelihood data channel for a disk drive includes an encoder connected to a data sequencer for converting user data blocks into a predetermined 8/9ths code such as a (0,4,4,) code. A precoder converts the 8/9ths code into class IV code. An analog write driver supplies the class IV code to a data transducer head during data write-to-disk operations. A read channel connected to the head amplifies and conditions analog signals during data read operations. A quantizer produces samples of the analog signals in accordance with a quantization clock generated by a clock generator. An adaptive FIR filter means is conditions the data samples in accordance with selectable, adaptive filter coefficients. A Viterbi detector puts out the class IV code from the filtered and quantized samples. A postcoder converts the detected class IV code into detected 8/9ths code. A decoder converts the detected 8/9ths code into user data and supplies user data to the sequencer.

Abstract: A magnetic card writing circuit is disclosed which enables the recording density of a recorded card to be selected, as desired, independently of the speed of a card conveying motor.

Abstract: A class IV partial response, maximum likelihood data channel for a disk drive includes an encoder connected to a data sequencer for converting user data blocks into a predetermined 8/9ths code such as a (0,4,4,) code. A precoder converts the 8/9ths code into class IV code. An analog write driver supplies the class IV code to a data transducer head during data write-to-disk operations. A read channel connected to the head amplifies and conditions analog signals during data read operations. A quantizer produces samples of the analog signals in accordance with a quantization clock generated by a clock generator. An adaptive FIR filter means is conditions the data samples in accordance with selectable, adaptive filter coefficients. A Viterbi detector puts out the class IV code from the filtered and quantized samples. A postcoder converts the detected class IV code into detected 8/9ths code. A decoder converts the detected 8/9ths code into user data and supplies user data to the sequencer.

Abstract: Sheets carrying bar codes are first stacked with their bar codes directed downward, then are pulled one at a time from the bottom of the stack, and then the pulled sheets are gripped and impelled into an upper upstream end of a guide whose downstream end opens into an outfeed hopper. The sheets slide in free fall downward in the guide in an upstream-to-downstream travel direction along a travel path without being gripped with the sheets passing over a basically planar upstream guide plate having, relative to the travel direction, an upstream edge and a downstream edge below the upstream edge and over a basically planar downstream glide plate having an upstream edge joined to the downstream edge of the upstream plate and a downstream edge below the upstream edge of the downstream plate. The downstream plate lies in a plane forming with the upstream plate an angle of slightly less than 180.degree. while forming with the horizontal an angle of between 17.degree. and 30.degree.

Abstract: The invention provides a system and method for making a data update, such as a directory update, to a magneto-optic disk which includes: copying designated directory sectors from the disk to a cache buffer, the designated directory sectors containing the portion of the directory which is to be updated; updating the directory portion to be updated in the cache buffer to provide an updated directory portion; writing the updated directory portion to a directory consistency block on the disk so as to provide a backup of the updated directory portion; erasing the designated directory sectors from the disk; writing the updated directory portion from the cache buffer to the designated directory sectors; verifying that the updated directory portion has been written to the designated directory sectors on the disk; and erasing the directory consistency block if there is verification that the updated directory portion has been written to the designated directory sectors on the disk.

Abstract: An optical information recording/reproducing apparatus for use in an optical card, in which a moving speed of the optical card is detected on the basis of an information signal read out from the optical card and in which the information signal is corrected with the aid of the thus detected moving speed. Therefore, the data recorded on the optical card can be read out in a stable manner even when the optical card is transferred with a variation of its moving speed; and such apparatus can be manufactured at a low cost.

Abstract: A tape data recording and reproducing system is disclosed which has an over-writing capability which can result in previously recorded data continuing to exist on the tape after the over-writing has been completed. The present invention uses cyclical redundancy check data that is normally recorded with the data to determine if the data recovered during reproducing is valid data.

Abstract: An arrangement for reproducing a digital signal from a track on a magnetic record carrier (20) includes a magnetic read head (21) having a magneto resistive element ( 107), and an equalizer filter circuit (23) for equalizing the output signal of the read head. The equalizer filter circuit (23) includes an IIR filter (29) and FIR (30). The IIR filter (29) equalizes magnitude and group delay of the signal applied to its input in a low frequency region of the signal frequency range. The FIR filter equalizes at least the magnitude of the signal applied to its input in a higher frequency region of the signal frequency range. Viewed in the direction of transport of the record carrier, the MR head has a front side and a back side. One of the sides (41) has a magnetic shielding for the MR element (107) which is larger than the magnetic shielding of the other side (40). The MR head (21) is positioned relative to the track so that the front side (40) has the lesser magnetic shielding.

Abstract: A magnetic head driving circuit is provided which has first and second transistors having the bases respectively connected to first and second input terminals and the collectors supplied with a power source voltage, third and fourth transistors having the collectors respectively connected to the emitters of the first and second transistors, and a magnetic head and surge absorbing resistor disposed in a parallel connection with each other between the emitters of the first and second transistors. Delay circuits are respectively disposed between the input terminal and the base of the fourth transistor and between the second input terminal and the base of the third transistor. If there has a time delay in inverting action generated between the first and second transistors, the reverse bias voltage acting between the base and emitter of the first and/or second transistor will be impossible to be increased, so that the switching time of the magnetic head current can be shortened.

Abstract: A write circuit in a magnetic disc drive writes data to a magnetic disc based on a write signal received. The write circuit includes a magnetic write head, an H-switch, and a headroom assistance circuit. The headroom assistance circuit includes a voltage divider, a capacitor, and a charging circuit for charging and discharging the capacitor based on the write signals so that increased voltage appears across the magnetic recording write head during switching of the current polarity by the H-switch.

Abstract: A digital signal recording and/or reproducing apparatus which converts an input analog signal into a digital signal and records the digital signal on a recording medium, or which reproduces a digital signal recorded on a recording medium and converts the digital signal into an analog signal has an analog signal level controller and a digital signal level controller connected in front of and after an A/D converter or a D/A converter and the digital signal level controller and the analog signal level controller are controlled in correlation with each other, whereby the S/N ratio of a recording signal or a reproducing signal can be improved.

Abstract: A device for reading code lines on a moving carrier in which the lines extend transverse to the direction of movement. The reading head extends across the web and has a row of sensors subdivided into groups. The sensors of each group have a length equal to the maximum length of the coding traces and the total row has a substantially greater length so that the sensors are subdivided along the row into groups. The signals from sensors of preceding groups in a direction of signal flow along the row are summed e.g. at operational amplifiers before being summed with the corresponding sensor outputs of subsequent groups.

Abstract: A circuit for generating a bias signal and an erase signal for use in a recording apparatus having a record head for recording an input analog signal on a magnetic tape, and an erase head for erasing information from the tape. A DC erase signal is applied to the erase head in response to the erase control signal to cause the erase head to erase information. An AC bias signal is generated and is combined with the input analog signal to make a record signal. The record signal is applied to the record head in response to the record control signal to record information on the tape. A controller generates an erase control signal and as record control signal. The AC bias signal is generated by an AC bias oscillator, such as a Hartley oscillator to reduce the noise contributed in the recording system. Use of a DC source to drive the erase head reduces the cost of the circuit, while maintaining a significant increase in the signal-to-noise ratio.