Optical head

Claim 2

An optical head for effecting the recording of information onto a recording medium or the reproduction of information from the recording medium, said recording medium having one or more signal tracks for storing information, comprising: a light source unit for supplying a light beam; a first optical system for directing the light beam from said light source unit to the recording medium; photodetector means; and a second optical system for directing the light beam from the recording medium to said photodetector means, said second optical system having a light beam divider for dividing the light beam from the recording medium into a first light beam and a second light beam, said light beam divider having a stripe-shaped light beam separating portion extending in a direction orthogonal to a direction correspoinding to the direction of a signal track on the recording medium.

Claim 3

An optical head according to claim 1, wherein said light divider has a stripe-shaped light beam separating portion extending in a direction orthogonal to the direction of a track.

Claim 4

An optical head for effecting the recording of information onto a recording medium or the reproduction of information from the recording medium, said recording medium having one or more signal tracks for storing information, comprising: a light source unit for supplying a light beam; a first optical system for directing the light beam from said light source unit to the recording medium; first and second photodetectors for receiving the light beam from said recording medium; a second optical system for directing the light beam from said recording medium to said first and second photodetectors, said second optical system having a light beam separating means for separating the light beam from the recording medium into two light beams, said light beam separating means having a first area for directing the incident light beam to said first photodetector and a second area for directing the incident light beam to said second photodetector; and signal processing means for processing the signals from said first photodetector and said second photodetector and generating a tracking signal and a focusing signal, said processing means controlling a focus state of the light beam on the recording medium by the focusing signal representative of the difference between the signals from said first and second photodetectors and controlling a tracking state of the light beam on the recording medium by the tracking signal resulting from detecting any variation in the distribution of light on said photodetectors in a direction orthogonal to a direction corresponding to the direction of a signal track on the recording medium.

Claim 5

An optical head for effecting the recording of information onto a recording medium or the reproduction of information from the recording medium, said recording medium having one or more signal tracks for storing information, comprising: a light source unit for supplying a light beam; a first optical system for directing the light beam from said light source unit to the recording medium; first and second photodetectors for receiving the light beam from said recording medium; a second optical system for directing the light beam from said recording medium to said first and second photodetectors, said second optical system having a light beam separating means for separating the light beam from the recording medium into two light beams, said light beam separating means having a first area for directing the incident light beam to said first photodetector and a second area for directing the incident light beam to said second photodetector; and signal processing means for processing the signals from said first photodetector and said second photodetector and generating a tracking signal and a focusing signal, said processing means controlling a focus state of the light beam on the recording medium by the focusing signal representative of the difference between the signals from said first and second photodetectors and controlling a tracking state of the light beam on the recording medium by the tracking signal resulting from detecting any variation in the distribution of light on said photodetectors in a direction orthogonal to a direction corresponding to the direction of a signal track on the recording medium.

Claim 6

An optical head according to claim 3, wherein said first and second photodetectors are two-division photodetectors and the division lines thereof are disposed so as to be coincident with the direction corresponding to the of the signal track.

Claim 7

An optical head for effecting the recording of information onto an opto-magnetic recording medium or the reproduction of information from the opto-magnetic recording medium, said recording medium having one or more signal tracks for storing information, comprising: a light source unit for supplying a light beam; a first optical system for directing the light beam from said light source unit to the opto-magnetic recording medium; first and second photodetectors for receiving the light beam from the opto-magnetic recording medium; a second optical system for directing the light beam from the opto-magnetic recording medium to said first and second photodetectors, said second optical system having light beam separating means for separating the light beam for the opto-magnetic recording medium into two light beams, said separating means having a first area for directing the incident light beam to said first photodetector and a second area for directing the incident light beam to said second photodetector; polarizing plates provided forwardly of said first photodetector and said second photodetector, respectively; and signal processing means for generating a focusing signal and a tracking signal on the basis of electrical signals obtained by said first and second photodetectors, said processing means including a frequency discriminator and passing the focusing signal representative of the difference between the signals from said first and second photodetectors to the frequency discriminator and effecting the control of a tracking state of the light beam on the opto-magnetic recording medium by the tracking signal resulting from detecting any variation in a distribution of light on said photodetectors in a direction orthogonal to a direction corresponding to the direction of a signal track on the opto-magnetic recording medium.

Claim 8

An optical head for effecting the recording of information onto an opto-magnetic recording medium or the reproduction of information from the opto-magnetic recording medium, said recording medium having one or more signal tracks for storing information, comprising: a light source unit for supplying a light beam; a first optical system for directing the light beam from said light source unit to the opto-magnetic recording medium; first and second photodetectors for receiving the light beam from the opto-magnetic recording medium; a second optical system for directing the light beam from the opto-magnetic recording medium to said first and second photodetectors, said second optical system having light beam separating means for separating the light beam for the opto-magnetic recording medium into two light beams, said separating means having a first area for directing the incident light beam to said first photodetector and a second area for directing the incident light beam to said second photodetector; polarizing plates provided forwardly of said first photodetector and said second photodetector, respectively; and signal processing means for generating a focusing signal and a tracking signal on the basis of electrical signals obtained by said first and second photodetectors, said processing means including a frequency discriminator and passing the focusing signal representative of the difference between the signals from said first and second photodetectors to the frequency discriminator and effecting the control of a tracking state of the light beam on the opto-magnetic recording medium by the tracking signal resulting from detecting any variation in a distribution of light on said photodetectors in a direction orthogonal to a direction corresponding to the direction of a signal track on the opto-magnetic recording medium.