Optical information recording medium

• US 4,839,883 A
• Filed: 06/25/1987
• Issued: 06/13/1989
• Est. Priority Date: 06/30/1986
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited 1006 OAZA Kadoma-Shi Osaka Japan
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Nagata, Kenichi, Yamada, Noboru
• Primary Examiner(s): Stephan, Steven L.
• Application Number:
  US07/066,229
• Time in Patent Office: 719 Days
• Field of Search: 369/100, 369/275, 369/283, 369/284, 369/286, 369/288, 346/135.1, 430/19, 430/945
• US Class Current: 369/286
• CPC Class Codes: G11B 7/258 of reflective layers
• CPC Class Codes: G11B 7/2595 based on gold
• CPC Class Codes: Y10S 430/146 Laser beam

Abstract

There is provided a rewritable tri-layer optical information recording medium of the phase change type having a high sensitivity. In this medium, a reflective layer is formed by a thin film of an Ni-Cr alloy or an Au-Cr alloy.

Claims

1. A reversible optical information recording medium comprising:

a substrate;

an absorptive layer, overlying the substrate, which absorbs a light of a wavelength of an irradiating laser beam for any one of recording, reproducing, and erasing and which may be reversibly switched to a state having different optical properties;

a reflective layer, overlying the absorptive layer, for reflecting a considerable portion of the light of an irradiating laser beam; and

a spacer layer interposed between said absorptive layer and said reflective layer,

wherein said reflective layer comprises a thin film of an Ni-Cr alloy or an Au-Cr alloy.

2. A recording medium according to claim 1, wherein said absorptive layer comprises a material which can reversibly cause a phase transition between a crystalline phase and an amorphous phase upon irradiation by a laser beam, and said reflective layer comprises a thin film of an Ni-Cr alloy or an Au-Cr alloy of a thermal diffusivity lower than that of Au or Al.

3. A recording medium according to claim 1, wherein said reflective layer is composed of an Ni-Cr alloy and when it is assumed that the composition of said alloy is Ni_100-x Cr_x, x is set to a value within a range of 10≦

x≦

90.

4. A recording medium according to claim 3, wherein said x is set to a value within a range of 20≦

x≦

80.

5. A recording medium according to claim 1, wherein a thickness of said thin Ni-Cr alloy film is set to a value within a range of 200 to 600 Å

.

6. A recording medium according to claim 1, wherein said reflective layer is composed of an Au-Cr alloy and when it is assumed that the composition of said alloy is Au_100-y Cr_y, said y is set to a value within a range of 2≦

y≦

30.

7. A recording medium according to claim 6, wherein said y is set to a value within a range of 10≦

y≦

20.

8. A recording medium according to claim 1, wherein a thickness of said thin Au-Cr alloy film is set to a value within a range of 100 to 600 Å

.

9. A recording medium according to claim 2, wherein said reflective layer comprises an Ni-Cr alloy film.

10. A recording medium as in claim 9 wherein said Ni-Cr alloy film has a composition of Ni_100-x Cr_x and x is set to a value in the range of 10≦

×

≦

90.

11. A recording medium according to claim 10, wherein x is set to a value within a range of 20≦

×

≦

80.

12. A recording medium according to claim 9, wherein a thickness of said thin Ni-Cr alloy film is 200 to 600 Å

.

13. A recording medium according to claim 2, wherein said reflective layer comprises an Au-Cr alloy.

14. A recording medium according to claim 13 wherein said Au-Cr alloy film has a composition of Au_100-y Cr_y and y is set to a value in the range of 2≦

y≦

30.

15. A recording medium according to claim 14, wherein y is set to a value within a range of 10≦

y≦

20.

16. A recording medium according to claim 13 wherein a thickness of said thin Au-Cr alloy film is set to a value within a range of 100 to 600 Å

.