Optical recording medium and method for using the same

• US 5,399,451 A
• Filed: 04/09/1993
• Issued: 03/21/1995
• Est. Priority Date: 03/14/1991
• Status: Expired due to Term

• Current Assignee: New Energy and Industrial Technology Development Organizatio, Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Hashida, Takashi, Kishimoto, Yoshio
• Primary Examiner(s): Bowers, Jr., Charles L.
• Assistant Examiner(s): McPherson, John A.
• Application Number:
  US08/045,541
• Time in Patent Office: 711 Days
• Field of Search: 430/19, 430/139, 430/945, 430/495, 430/962, 430/343, 430/345, 430/333, 346/135.1, 369/288, 365/111
• US Class Current: 430/19
• CPC Class Codes: G11B 7/004 Recording, reproducing or erasing methods; Read, write or erase circuits therefor magneto-optical systems G11B11/105
• CPC Class Codes: G11B 7/244 comprising organic materials only
• CPC Class Codes: Y10S 430/146 Laser beam
• CPC Class Codes: Y10S 430/163 Radiation-chromic compound

Abstract

An optical recording medium contains a fluorescent material and a photo-reactive bistable quencher. Information is digitally recorded by utilizing the bistable isomers of the photo-reactive bistable quencher by irradiating the medium with a light in the wavelength to be absorbed by the fluorescent material, whereby energy is transferred from the fluorescent material to the photo-reactive bistable quencher. Reading is made by irradiating the medium with a weaker light and detecting the fluorescence emitted by the fluorescent material.

Claims

1. In an optical recording medium comprising at least one recording layer containing as essential material a composition which includes

at least one dye and

at least one photochromic compound,

the improvement that

said dye is a fluorescent material,

said photochromic compound is a photo-reactive bistable quencher for quenching the fluorescence emitted from said fluorescent material, and

amount of said photo-reactive bistable quencher is in excess for the amount actually required for quenching said fluorescence.

2. A method for erasing information stored in or for initializing an optical recording medium comprising at least one recording layer containing as essential material a composition which includes

at least one dye and

at least one photochromic compound,

the improvement that

said dye is a fluorescent material.

said photochromic compound is a photo-reactive bistable quencher for quenching the fluorescence emitted from said fluorescent material, and

amount of said photo-reactive bistable quencher is in excess for the amount actually required for quenching said fluorescence,

which method comprises:

irradiating said recording layer with a light at the wavelength in an absorption band of a colorless isomer of said photochromic compound, and thereby

converting a portion of said first photochromic compound into its colored isomer.

3. A method for erasing information stored in or for initializing an optical recording medium comprising at least one recording layer containing as essential material a composition which includes

at least a first photochromic compound with fluorescent activity and takes either one of two states of colorless isomer and of colored isomer, and

at least one photo-reactive bistable quencher, which is also a second photochromic compound, takes either one of two states of long wavelength isomer and of short wavelength isomer and quenches the fluorescence emitted from said first photochromic compound,

said one photo-reactive bistable quencher being a control agent for controlling the photochromic reactivity of said photochromic compound,

which method comprises:

irradiating said recording medium with a light at the wavelength in an absorption band of a short wavelength isomer of said photo-reactive bistable quencher included in said recording layer thereby converting said photo-reactive bistable quencher into its long wavelength isomer and activating it as a quencher, and then

irradiating said recording layer with a light at the wavelength in an absorption band of said colorless isomer of said first photochromic compound included in said recording layer thereby converting said colorless isomer of said first photochromic compound into its colored isomer.

4. A method for recording information on an optical recording medium comprising at least one recording layer containing as essential material a composition which includes

at least a first photochromic compound with fluorescent activity and takes either one of two states of colorless isomer and of colored isomer, and

at least one photo-reactive bistable quencher,which is also a second photochromic compound, takes either one of two states of long wavelength isomer and of short wavelength isomer and quenches the fluorescence emitted from said first photochromic compound,

said one photo-reactive bistable quencher being a control agent for controlling the photochromic reactivity of said photochromic compound,

which recording medium has previously been erased or initialized by irradiating said recording medium with a light at the wavelength in an absorption band of a short wavelength isomer of said photo-reactive bistable quencher included in said recording layer thereby converting said photo-reactive bistable quencher into its long wavelength isomer and activating it as a quencher, and then by irradiating said recording layer with a light at the wavelength of an absorption band of said colorless isomer of said first photochromic compound included in said recording layer thereby converting said colorless isomer of said first photochromic compound into its colored isomer,

which method comprises:

irradiating a light at the wavelength in an absorption band of a long wavelength isomer of said photo-reactive bistable quencher thereby inactivating it as a quencher by converting said photo-reactive bistable quencher into its short wavelength isomer, and then

irradiating said recording layer with a light the wavelength in an absorption band of the colored isomer of said first photochromic compound thereby converting said first photochromic compound into its colorless isomer.