Optical recording medium discriminating apparatus using laser beams of different wavelengths
First Claim
1. An apparatus for recording and reproducing information from an optical recording medium, said apparatus comprising:
- a first device which emits light at the optical recording medium, and receives the light emitted at and reflected by the optical recording medium to detect an intensity of the reflected light having a first wavelength;
a second device which emits light at the optical recording medium, and receives the light emitted at and reflected by the optical recording medium to detect an intensity of the reflected light having a second wavelength, wherein the second wavelength is longer than the first wavelength; and
a discriminator which determines a type of the optical recording medium according to a difference between the intensities of the reflected light detected by said first and said second devices thereby discriminating the type of the optical recording medium according to the difference in reflectance detected by said first and second devices, wherein the difference indicates a wavelength dependence of reflectance of the optical recording medium.
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Accused Products
Abstract
In an optical recording and reproducing apparatus, two light sources such as a laser diode of different wavelengths from each other are provided, and photosensors receive the light emitted by the light sources and reflected by the optical recording medium. Before recording or reproduction is started, the type of optical recording medium having a different wavelength dependent reflectance is discriminated. Because two wavelengths are used, the difference of the outputs is large, and the type of the optical recording medium is discriminated reliably according to the outputs of the photosensors. Then, the operation of the apparatus is stabilized according to the type of the optical recording medium by optimizing the laser power, the gain of the controller, the revolution number of the medium or the like.
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Citations
17 Claims
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1. An apparatus for recording and reproducing information from an optical recording medium, said apparatus comprising:
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a first device which emits light at the optical recording medium, and receives the light emitted at and reflected by the optical recording medium to detect an intensity of the reflected light having a first wavelength; a second device which emits light at the optical recording medium, and receives the light emitted at and reflected by the optical recording medium to detect an intensity of the reflected light having a second wavelength, wherein the second wavelength is longer than the first wavelength; and a discriminator which determines a type of the optical recording medium according to a difference between the intensities of the reflected light detected by said first and said second devices thereby discriminating the type of the optical recording medium according to the difference in reflectance detected by said first and second devices, wherein the difference indicates a wavelength dependence of reflectance of the optical recording medium. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification