Apparatus for optically recording and reproducing information in record tracks on a rotatable record disc

Claim 1

An apparatus for recording and reproducing information in record tracks on a rotable record disc, comprising: disc driving means (13, 15) for rotating the record disc (11) loaded thereon; first and second optical head means (19a, 19b) each facing the rotable record disc (11) and positioned to face each other with a central portion of said disc (11) loaded on said disc driving means (13, 15); and head driving means (21, 21b, 23a, 23b) for moving said optical head means (19a, 19b); characterized in that each of said first and second optical head means (19a, 19b) generates a first light beam used selectively for erasing and writing an information signal in the record track and a second light beam used for reading an information signal from the record track and causes the first and second light beams to impinge upon the record track on the rotable record disc (11) rotated by said disc driving means (13, 15) in such a manner that the first light beam precedes the second light beam in a direction along the record track, and head driving means (21a, 21b, 23a, 23b) move said first and second optical head means (19a, 19b) simultaneously to be close to or distant from each other in a radial direction on the rotable record disc (11) loaded on said disc driving means (13, 15).

Claim 5

An apparatus according to any one of claims 1 to 4, characterized in that each of said first and second optical head means (19a, 19b) comprises first and second laser light sources (30, 31) for generating said first and second light beams, respectively, object lens means (36) provided in common to said first and second light beams for focusing each of said first and second light beams from said first and second laser light sources (30, 31) on the rotatable record disc (11) loaded on said disc driving means (13, 15), and optical means (32-35, 37, 38) for forming optical paths through which said first and second light beams pass, respectively.

Claim 9

An apparatus according to any one of claims 5 to 8, characterized by further comprising signal generating means (51a, 51b) for producing a reproduced information signal (Si), a tracking error signal (St) and a focus error signal (Sf) based on a detection output signal obtained from said photodetecting means (40, 44, 46).

Claim 10

An apparatus according to any one of claims 1 to 9, characterized by further comprising first magnetic field generating means (17a) disposed to face said first optical head means (19a) with the rotatable record disc (11) loaded on said disc driving means (13, 15) between, and second magnetic field generating means (17b) disposed to face said second otpical head means (19b) with the rotatable record disc (11) loaded on said disc driving means (13, 15) between, each of said first and second magnetic field generating means (17a, 17b) extending in the radial direction on the rotatable record disc (11) loaded on said disc driving means (13, 15).

Claim 12

An apparatus according to any one of claims 1 to 11, characterized by further comprising light beam control means (49a, 49b) for causing said first light beam from one of said first and second optical head means (19a, 19b) to write the information signal in sectors each forming a portion of the record track and for causing said second light beam from one of said first and second optical head means (19a, 19b) to read the information signal written in the sectors, and operation control means (61) for controlling the operation of said first and second optical head means (19a, 19b) and the operation of said light beam control means (49a, 49b).