Abstract: An optical device has a plurality of LED sources distributed at the nodes of a rectangular lattice and solid state bistable electronic circuits associated with each source for delivering a predetermined current to the source responsive to a temporary control signal applied to a now line corresponding to the source and for maintaining it until it is cut off by another signal.In a modified embodiment, a plurality of LED sources are associated to the same solid state circuit which has a column interface having several outputs connected to respective column lines for delivering signals representative of conditions to be given to the LED sources one row at a time and a row interface having several outputs connected to respective row lines for selecting the row to be controlled. The circuit is again arranged for maintaining each of the LED sources in energized condition after it has been energized by the column interface and until it is cut-off by a specific signal.

Abstract: Process for the regeneration of synchronizing signals used for writing and/or reading recorded digital data or for recording on an optical data carrier, wherein the synchronizing signals are regenerated in phase by determining the phase shift of the center of specific pulses with respect to a clock signal. According to a preferred variant, the specific data and the useful information data are coded by a N.R.Z-type code, the specific data being associated with pulse durations not used in the N.R.Z. code for recording information data. The specific data can be recorded in time multiplexing with digital information data or, according to a preferred variant, in the form of flags at regularly spaced locations on the tracks which define between them zones intended for the recording of data blocks. The recording of these flags can take place prior to any recording of digital information data in preetched form.

Abstract: Process for the regeneration of synchronizing signals used for writing and/or reading recorded digital data or for recording on an optical data carrier, wherein the synchronizing signals are regenerated in phase by determining the phase shift of the center of specific pulses with respect to a clock signal. According to a preferred variant, the specific data and the useful information data are coded by a N.R.Z.-type code, the specific data being associated with pulse durations not used in the N.R.Z. code for recording information data. The specific data can be recorded in time multiplexing with digital information data or, according to a preferred variant, in the form of flags at regularly spaced locations on the tracks which define between them zones intended for the recording of data blocks. The recording of these flags can take place prior to any recording of digital information data in preetched form.

Abstract: Process for generating synchronizing signals used for writing and/or reading recorded digital data or recording on an optical data carrier, in which the synchronizing signals are obtained from basic clock signals regenerated in phase with the aid of the determination of the phase shift of a specific pulse relative to the clock signal. According to a preferred variant, the specific data and the useful information data are coded according to the NRZ code. The specific data are associated with pulse times not used in the NRZ code for the recording of the information data. The synchronizing signals generated on the basis of the reading of these flags can then be used for writing during the information data recording phases.