Noise reduction system for optical record and reproduction apparatus using auto-power controlled semiconductor laser device

An apparatus for suppressing or eliminating a noise from a reproduced information signal read out of an optical record carrier body using a solid-state light emission device, said apparatus comprising:

• driver means for receiving a control voltage signal externally supplied thereto to designate a light emission of said light emission device, and for supplying said light emission device with a corresponding drive current signal in response to the control signal;
• optical detector means for partially receiving a light sent forth from said light emission device, and for generating a detection current signal corresponding in magnitude to a detected amount of light;
• compensator means coupled to said driver means and said optical detector means, for generating a voltage signal that compensates for a possible variation in the light sent forth from said light emission device, which is supplied to said driver means;
• noise reduction means for receiving the voltage signal and the reproduced information signal, for using said voltage signal as a noise monitor signal, for subtracting this noise monitor signal from said reproduced information signal to generate a noise-suppressed reproduction signal;
• and
• optical means coupled to said optical detector means, for causing a first optical system associated with said optical detector means to be equivalent in optical condition with a second optical system for reproduction of the information signal.

An optical record and reproduction apparatus for recording an information on an optical record carrier body, said apparatus comprising:

• a solid-state light emission device;
• control means coupled to said light emission device, for controlling said light emission device so that said device sends forth a light beam indicative of information to be recorded;
• optical guide means for optically dividing the light beam into a first component and a second component, for causing the first component to be introduced onto said carrier body as a recording beam, and for causing the second component to propagate along a preselected path;
• optical detector means for at least partially receiving the second component of said light beam, and for generating a detection signal corresponding in magnitude to a detected amount of light;
• reference signal generator means having storage means for storing a plurality of reference signals indicative of preselected optical output data for said light emission device, and selector means for selecting a suitable reference signal from the reference signals stored in said storage means in accordance with the information to be recorded presently;
• and
• subtraction means connected to said control means, said optical detector means and said selector means, for providing an electrical difference signal indicative of a difference in magnitude between the reference signal selected by said selector means and the detection signal of said optical detector means, and for causing said difference signal to be supplied to said control means as a light emission control signal.

An apparatus for suppressing or eliminating noise from a reproduced information signal read out of an optical record carrier body using a solid-state light emission device, said apparatus comprising:

• driver means for receiving a control voltage signal externally supplied thereto to control alight emission of said light emission device, and for supplying said light emission device with a corresponding drive current signal in response to the control voltage signal;
• optical detector means for partially receiving light emitted from said light emission device, and for generating a detection current signal corresponding in magnitude to a detected amount of light;
• compensator means, coupled to said driver means and said optical detector means, for generating a voltage signal that compensates for a possible variation in the light emitted from said light emission device, which is supplied to said driver means;
• noise reduction means for receiving the voltage signal and the reproduced information signal, for using said voltage signal as a noise monitor signal, and for subtracting said noise monitor signal from said reproduced information signal to generate a noise-suppressed reproduction signal;
• and
• optical means optically coupled to and positioned in front of said optical detector means, for causing a first optical system associated with said optical detector means to have an equivalent optical condition as a second optical system for reproduction of the information.