United States Patent [19] [ii] Patent Number: 4,679,184
Yoshida et al. [45] Date of Patent: Jul. 7, 1987
[54] OPTICAL RECORDING AND
REPRODUCING APPARATUS HAVING
ERASING BEAM SPOT WITH
ASYMMETRICAL INTENSITY
DISTRIBUTION
[75] Inventors: Tomio Yoshida, Katano; Shunji
Ohara, Higashiosaka, both of Japan
[73] Assignee: Matsushita Electric Industrial Co., Ltd., Osaka, Japan
[21] Appl. No.: 739,872
[22] Filed: May 31,1985
[30] Foreign Application Priority Data
Jun. 8, 1984 [JP] Japan 59-118531
Aug. 31, 1984 [JP] Japan 59-181782
[51] Int. Q." G11B7/00
[52] U.S. a 369/112; 369/109;
369/122
[58] Field of Search 369/99, 109, 110, 112,
369/113, 122, 124, 275; 346/76 L
[56] References Cited
U.S. PATENT DOCUMENTS
4,264,986 4/1981 Willis 369/275 X
4,383,261 5/1983 Goldberg 346/1.1
4,403,318 9/1983 Nagashima et al 369/116 X
4,498,159 2/1985 Daimon 369/44
4,516,234 5/1985 Nakagawa et al 369/109
4,564,931 1/1986 O'Hara et al 369/122 X
4,566,088 1/1986 Yoshida et al 369/116 X
Primary Examiner—Aristotelis M. Psitos
Attorney, Agent, or Firm—Spencer & Frank
[57] ABSTRACT
Disclosed is an optical recording and reproducing apparatus having an erasing function. The invention aims at providing a practical apparatus which can effect recording, reproducing and erasing of signals in an erasable recording film by applying laser beams thereto. A substantially circular first fine beam spot is formed by a beam source such as a laser, and an elliptic second beam spot for erasing purposes is formed by another beam source such as a laser, with both beam spots are disposed in close proximity of each other on the same guide track. The erasing beam spot is elongated and has an axis which is tangent to the guide track on the recording medium. The power of intensity profile of the erasing beam spot is so controlled that the highest intensity is obtained at the leading end portion of the erasing beam spot as viewed in the direction of the scan, so that the signal can be erased stably and reliably with minimal erasing power. The portion of the recording medium scanned by the erasing beam spot is scanned by the recording beam spot so that the erasing and recording are carried out substantially simultaneously.
10 Claims, 14 Drawing Figures
