Abstract: An optical information recording and reproducing apparatus comprising: a reproduction signal processing circuit including one or more elements which have respective variable parameters for changing states of the elements, respectively at the time of read-out of data from a recording medium such that the data is read out from the recording medium by changing the states of the elements.

Abstract: An optical disc record and playback apparatus is provided in which it is possible to record and play back information on erasable discs, as well as write-once discs. When a disc is first inserted into the record and playback apparatus, data written on a control track of the disc is read to identify whether the disc is erasable or write-once. Optimum record and playback parameters are then set depending upon the type of disc. Another aspect of the invention relates to an optical disc in which data representative of the optical sensitivity of the disc is recorded thereon during manufacture. The data is read by the record and playback apparatus and used to adjust the optical recording power so as to compensate for differences in optical sensitivities of different discs.

Abstract: An optical recording and reproducing apparatus stably set the gains (focus, tracking) corresponding to the respective layers at the insertion time of a recording medium having a multilayer record membrane. The optical recording and reproducing apparatus uses a recording medium having a multilayer membrane construction wherein the recording membranes are formed in a stage shape, is not superposed in the inner periphery or the outer periphery with respect to the laser transmission side, and has a circuit for detecting the number of the recording membranes, and a circuit for switching to a focus gain or a tracking gain in conformity with the recording medium, and a focus driving circuit for effecting a focus drawing-in operation. The driving circuits are driven so that they may be rotated or run into a condition of effecting capable of focus drawing-in operation, and thereafter the focus drawing-in operation is effected in the specific position of the recording medium.

Abstract: A recording apparatus overwrites an input signal having pulse duration periods and pulse spacing periods to an optical disk by irradiation of a laser beam to form recording marks corresponding to the pulse duration periods. The apparatus includes a detector for detecting a leading edge of the pulse duration period and for producing a start signal thereupon, another detector for detecting a trailing edge of the pulse duration period and for producing a stop signal thereupon, a pattern setting circuit for setting a predetermined basic pattern, and a pattern generator for generating the basic pattern from its beginning in response to the start signal and for terminating the generation of the basic pattern in response to the stop signal. The apparatus further includes a circuit for forming a modulated signal using a full or portion of the basic pattern produced from the pattern generator. The laser output is produced in accordance with the modulated signal.

Abstract: A recording apparatus overwrites an input signal having pulse duration periods and pulse spacing periods to an optical disk by irradiation of a laser beam to form recording marks corresponding to the pulse duration periods. The apparatus includes a detector for detecting a leading edge of the pulse duration period and for producing a start signal thereupon, another detector for detecting a trailing edge of the pulse duration period and for producing a stop signal thereupon, a pattern setting circuit for setting a predetermined basic pattern, and a pattern generator for generating the basic pattern from its beginning in response to the start signal and for terminating the generation of the basic pattern in response to the stop signal. The apparatus further includes a circuit for forming a modulated signal using a full or portion of the basic pattern produced from the pattern generator. The laser output is produced in according with the modulated signals.