Abstract: A digital data reproducing apparatus and method which allows reproduction for a long period of time without deterioration in picture quality. Data are reproduced from an optical disk by a pickup and are transferred to and stored in a ring buffer memory. Data read from the ring buffer memory are transferred to and stored into a video code buffer of an encoder section. The data stored in the video code buffer are encoded in the encoder section and displayed on a display. A track jump judging circuit produces a track jumping instruction to cause the pickup to track jump back to a preceding track when the amount of data stored in the ring buffer memory reaches a predetermined value.

Abstract: In an optical recording medium on which the main information is recorded on a pre-formed recording track along the track direction and in which the recorded data are read out by opticaL means, frame sync signals based on the same format as the format for the main information are pre-recorded by offsetting the recording track itself along its width for each frame as an information recording unit, for facilitating frame synchronization and simplifying the construction through the use of a sole common synchronizing circuit. The information pre-recorded by offsetting the track itself along its width includes not only the frame sync signals but also any reproduce-only information for increasing the disc recording capacity.

Abstract: A multi-value recorded data detecting method which can achieve accurate detection of multi-value data irrespective of a level variation or an amplitude variation of an input reproduction signal. A reproduction signal from a record medium, on which multi-value data are recorded, is converted from an analog signal into a digital signal in response to a reference clock signal to obtain signal level data. The signal level data are stored into memory means, and distribution information of the signal level data stored in the memory means are found out for each predetermined signal unit. Then, a threshold value or values are set in accordance with the distribution information, and the signal level data from the memory means are compared with the threshold value or values to obtain multi-value data.

Abstract: After servo information for positioning is written onto a magnetic disk medium on a track unit basis by a head, the servo information of the same track is read out and stored into a memory. Subsequently, during the seeking operation to move the head to the next track, the servo information at a time point when the head is on-tracked is arithmetically operated from the preceding read-out servo information stored in the memory and the present read-out servo information and the quality is verified.

Abstract: A disc reproducing aparatus is provided which is able to read out all of the data stored on the disc in a short time. The disk reproducing apparatus reproduces data stored on a disc and comprise a device for rotating the disc and a data processing device having a plurality of optical pickup devices for reading the data from the rotating disc, such that each pickup device reads a different part of the data area.

Abstract: A recording and read system capable of recording and reading information from a record carrier with a higher speed than that with which it is received or supplied. In order to compensate for differences between the recording speed and the read speed and between the receiving speed and the supply speed the device includes an input buffer memory and an output buffer memory. In order to minimize the required storage capacity of the buffer memories, the device comprises a control unit which is loaded with a control program which temporarily interrupts the recording and read process in such a way that the degree of filling of the capacity of the input buffer memory and of the capacity of the output buffer memory remains within specific limits.

Abstract: An optical disc reproducing apparatus can play multiple types of discs. The apparatus biases a focusing error signal based on the disc type. An analyzer receives reflected light of a light beam irradiated from an optical pick-up to a disc. A focus error signal is generated based on the signal supplied the analyzer. A switch selectively provides one of first and second bias voltages. A control controls which of the first and second bias voltages the switch provides based on the type of disc. The bias voltage is added to the focus error signal. An object lens of the optical pickup is driven based on the focus error signal with the bias voltage added.

Abstract: A digital filter (5) filters outputs of an A/D converter (3). An adder (10) adds outputs from the digital filter (5) and delayed outputs from a delay (9). An extracting circuit takes out driving data (11) from the added data. Error data, which are remaining data of the added data after extraction of the driving data by the extracting circuit (6) are delayed a predetermined period of time by a delay (9) and inputted to the adder (10). A driving unit (9) drives an optical system (2) according to the driving data (11). The error data (12) are fed back and added to outputs of the digital filter (5), thereby improving accuracy in driving of the optical disk system and, as a result, obtaining reliable controllability and high accuracy in positioning in the optical disk system.

Abstract: Methods of and information recording devices for recording and/or inhibiting recording of a signal including copy bits on a record carrier, and a record carrier including that signal. The signal has successive information frames including main data and subcode data. The subcode data of the information frames make up successive subcode frames having copy bits with logic values which alternate among the subcode frames in accordance with a predetermined pattern. Each subcode frame has at least one copy bit. In one of the embodiments, the signal is received and a determination is made whether to inhibit its recording on the basis of the predetermined pattern exhibited by the logic values of the copy bits contained in the subcode frames. In another embodiment the subcode frames are replaced by substitute subcode frames having copy bits with logic values which alternate among the substitute subcode frames in accordance with a selected pattern prior to recording of the signal.

Abstract: Method and apparatus for recording information on an overwritable optical disk in which data is recorded on the disk with a writing beam spot while shifting the writing beam spot in a radial direction by a pitch smaller than the diameter of the writing beam spot for each rotation of the disk. In a reading operation, a reading beam having a shorter wavelength than that of the writing beam is used to read recorded data.

Abstract: A compact disk playback/recording system having a compact disk playback apparatus and a cassette recording apparatus.

Abstract: An optical tracking system 10 is provided which comprises a beam source 12 which generates a light beam. The light beam travels through a splitter/filter 14 and proximate a DMD array 16. The DMD array 16 is controlled by a DMD array control system 18 which causes a single element within the DMD array to deflect the light beam towards a selected track on an optical storage medium 22. The optical storage medium 22 reflects the beam dependent upon the data stored on the selected track. The reflected beam is deflected by the DMD array 16 back to the splitter/filter 14 which separates the reflected beam from the impinging beam and directs the reflected beam to a detector 24 which discerns the information stored in the storage medium 22 responsive to the receipt of the reflected beam.

Abstract: In a normal sector mark detection routine, using a wide open search window bits read from an optical data disk are searched for the presence of a sector mark pattern. Following detection of the pattern, using a search window of programmable width, a predefined region of the next sector is searched to locate a sector mark pattern. If the pattern is found, a sector mark found signal is generated. If the pattern is not found, a pseudo sector mark signal is generated. This sequence is repeated until either a subsequent sector mark pattern is detected, a predetermined number of pseudo sector mark signals generated or an exit command is received. Data is read from a sector in response to a sector mark found signal or pseudo sector mark signal. In a constant sector mark mode, the disk is searched, with the window wide open. Sector mark patterns are detected continuously to carry out media certification.

Abstract: A digital noise blanking circuit associated with a Compact Disk-Read Only Memory (CD-ROM) system for preventing a digital noise from being output during power on/off and a computer re-set includes a first mute controller for providing a first mute signal for eliminating a digital noise generated during a power on/off, a second mute controller for providing a second mute signal for eliminating the digital noise generated during a reset of the computer operation and a muting circuit for cutting off the digital noise generated from an audio output terminal of the CD-ROM system by the first and second mute signals output from the first and second mute controller and a third mute signal output from a microcomputer of the CD-ROM system.

Abstract: Apparatus and method for asynchronous gain adjustment are provided for data detection in a partial-response maximum-likelihood (PRML) data channel. The PRML data channel includes an analog to digital converter (ADC) having a normal operating range and a filter, gain and timing control coupled to the ADC. A plurality of samples are detected from the ADC. Each of the detected samples are sequentially compared with predetermined threshold values. The predetermined threshold values include a zero value, and a minimum value and a maximum value of the normal operating range of the ADC. An absolute value of each of the detected samples are sequentially compared with a forth predetermined threshold value. A gain adjustment correction value is determined utilizing the sequentially compared values.

Abstract: A method of recording data includes irradiating a light spot on an optical card having a recording area including a user data region and an index data region arranged adjacent to each other. User data is recorded on the user data is recorded region and index data on the index data region. User data relates to the user of an optical card and may be stored in accordance with the usage of the card, such as name and age of the user. Index data is necessary for retrieving a desired user data. An optical spot is moved from a track to another track to a plus side in the user data region during the recording, whereas in the index data region, the optical spot is moved from track to track to the minus side.

Abstract: A medium testing method capable of testing a WORM (Write Once Read Memory) type optical disk efficiently and accurately, and a system for practicing the method. A playback unit plays back a disk to output a radio frequency (RF) signal representative of data stored therein. As the RF signal is routed through an RF amplifier to an error detecting unit, the detecting unit decodes the signal frame by frame and detects correctable errors and uncorrectable errors while correcting the errors of each frame. A track information detecting unit reads track information out of lead-in areas and outputs them. An error processing unit determines gaps between consecutive tracks by calculation on the basis of the track information. Subsequently, the error processing unit removes errors lying in the gaps from the error information received from the error detecting unit.

Abstract: A miniature rotary actuator optical head assembly incorporating data and servo detecting elements mounted inside a source/detector module, which is located on the rotary actuator arm adjacent to the pivot point of the rotary actuator arm. The miniature rotary actuator optical head also includes a miniature focus motor which supports a fold mirror and an objective lens and repositions the fold mirror and objective lens simultaneously whenever a focus error is received. The focus motor can be actuated by a magnetic bias field that originates external to the rotary actuator arm, particularly the magnetic bias field generated for magneto-optical recordation. The optical assembly may also include two stage tracking by mounting the light source on a pair of lateral movement flexures and supplying a fine tracking error signal to actuate the movement of the light source.

Abstract: In a spindle servo circuit for controlling rotation of a disc, a loop gain of a spindle servo can be varied and a reproduced synchronizing signal from the disc and a reference signal are compared with each other. A phase difference signal and a frequency difference signal that are compared results are chopped by a chopper clock. A loop gain of a servo circuit is varied by varying a duty ratio of the chopper clock and the loop gain can be varied by controlling the duty ratio of the chopper clock in response to a radius of the disc or a revolution rate of the disc.

Abstract: The present invention provides an optical disc comprising a main-image signal recording area holding a signal of a main image for a display, and a sub-image signal recording area holding a signal of a sub image to be displayed including an image of a time counted down in accordance with a progress of a sub-image signal reproduction. Furthermore it provides an image signal transmitting apparatus for repeatedly transmitting a main-image signal and a sub-image signal one after the other by utilizing such optical disc, the image signal transmitting apparatus comprising a image signal reproduction device for reproducing the main-image signal and the sub-image signal, a cycle time memory for memorizing a main-image signal transmission cycle, and a control device for obtaining a time difference between the cycle and time required for the main-image signal reproduction as well as control the image signal reproduction device.