Abstract: Disclosed is an optical recording and reproducing apparatus capable of recording in a position which is properly synchronous with the position of the last pit in a sector on which a recording was made, the first pit in a sector on which a recording is to be subsequently made. This apparatus is characterized by a recording circuit having a data demodulating circuit which includes a synchronizing signal separating circuit. The synchronizing signal separating circuit outputs a synchronizing signal on the basis of a pit detection signal generated in response to the detection of pits formed on a track of a recording medium and representing data to be recorded.

Abstract: An optical data storage accessing apparatus which includes a first light projecting unit including a laser diode for projecting data recording light onto a data storage medium, a second light projecting unit for projecting data recording light onto the data storage medium, and a light receiving unit. The light receiving unit receives the data reading light after it is reflected by the data storage medium to read data recorded on the data storage medium. An optical unit joins the data recording light and the data reading light and separates data reading light reflected from the data storage medium from the data recording light.

Abstract: There is provided an optical card information recording/playing back apparatus comprising: an optical system for irradiating a light beam for reproducing recorded information onto information recording tracks of the optical card on which pit trains indicative of recording information are formed; a photo detector for receiving the reflected light from the optical card and outputting a photo sensing signal; a pit correspondence signal producing circuit for detecting a peak of the photo sensing signal and producing a pit correspondence signal which changes in correspondence to a pit position on the basis of the result of the peak detection; a frequency/voltage converter for converting a frequency of the pit correspondence signal to a voltage; and a discrimination signal producing circuit for comparing a voltage output of the frequency/voltage converter with a reference value and producing an information presence/absence discrimination signal.