Radiant energy – Photocells; circuits and apparatus – With circuit for evaluating a web – strand – strip – or sheet
Reexamination Certificate
1998-02-20
2001-05-01
Le, Que T. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
With circuit for evaluating a web, strand, strip, or sheet
C250S559270, C250S201500, C356S389000
Reexamination Certificate
active
06225638
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a disc discrimination device and a disc discrimination method capable of discriminating what type of disc is loaded on a disc apparatus on which a different type of disc such as a CD, DVD and the like can be loaded.
2. Description of the Related Art
Recently, there have been developed disc apparatuses on which a different type of disc can be loaded. In this case, what type of disc is loaded on the disc apparatus must be discriminated.
However, a CD (Compact Disc), DVD (Digital Versatile Disc), CD-ROM, etc. have the same disc diameter of 12 cm and the clamping center hole thereof also has the same diameter. Thus, a type of disc cannot be discriminated from only the shape and size thereof.
To cope with this problem, conventional disc apparatuses employ such a method of discriminating a type of disc loaded thereon that the signal recorded on the disc is read by an optical head by rotating the disc when it is loaded to thereby determine the transfer velocity and arrangement of the thus read signal.
However, the method of discriminating a type of disc loaded on the disc apparatus by rotating the disc and reading its signal by the optical head cannot instantly discriminate the type just after the disc is loaded and a long time is required to the completion of the discrimination.
When, for example, only two types of disc, namely, the CD and DVD are discriminated by the above method, it is sufficient for a control circuit to distinguish only two types of signal. However, in a disc apparatus on which more types of disc are loaded, it is necessary for the control circuit to discriminate a plurality of types of signal and the discrimination method effected by the control circuit is made very complex.
An object of the present invention for solving the above problem of prior art is to provide a disc discrimination device and a disc discrimination method capable of discriminating a disc in a short time without the need of reading the signal recorded on the disc.
Another object of the present invention is to provide a disc discrimination device and a disc discrimination method capable of certainly discriminating respective types of disc even in a disc apparatus on which many types, namely, three types or more of disc are loaded.
SUMMARY OF THE INVENTION
A disc discrimination device of the present invention provided with a disc apparatus on which loaded is a different type of disc whose thickness from a front surface to a recording surface is different is characterized by comprising light irradiation means for obliquely irradiating detection light onto the recording surface, two light receiving regions for receiving the reflected light reflected from the recording surface, means for determining the difference between the quantities of reflected light received by the two light receiving regions and discrimination means for discriminating a disc based on the difference.
In the invention, a disc can be discriminated by the difference between the regions where the reflected light returns when the detection light is obliquely irradiated onto the recording surface. The above two light receiving regions may be provided with two light receiving elements such as photodiodes with a specific area which are disposed thereto adjacent to each other or may use a photodiode divided into two portions. Otherwise, they may use light receiving means such as a CCD having a multiplicity of portions for detecting light by dots and form the light receiving means to two regions capable of detecting the reflected light. These modifications are applicable to the following inventions.
A disc discrimination device of the present invention provided with a disc apparatus on which loaded is a different type of disc in which the reflection factor of light is different on a recording surface is characterized by comprising light irradiation means for irradiating detection light onto the recording surface, light receiving means for receiving the light reflected from the recording surface and discrimination means for discriminating a disc based on the quantity of reflected light received by the light receiving means.
According to the invention, it is possible to discriminate a disc in which the reflection factor on a recording surface is different with respect to a specific wavelength can be discriminated.
A disc discrimination device of the present invention provided with a disc apparatus on which loaded are a plurality of types of disc which include a disc whose thickness from a front surface to a recording surface is different and a disc in which the reflection factor of light is different on a recording surface is characterized by comprising light irradiation means for obliquely irradiating detection light onto the recording surface, two light receiving regions for receiving the reflected light reflected from the recording surface, means for determining the difference between the quantities of reflected light received by the two light receiving regions, means for determining the sum of the quantities of reflected light received by the two light receiving regions and discrimination means for discriminating a type depending upon the difference between the thicknesses from the front surface of the disc to the recording surface thereof based on the difference as well as discriminating a type depending upon the difference between the reflection factors of the light on the recording surface based on the sum.
In the invention, a disc can be discriminated by detecting both the difference between the thicknesses of the protective layer of the disc and the difference between the reflection factors of the light having a specific wavelength on the recording surface of the disc based on the quantities of reflected light received by the two light receiving regions. The two types of discrimination executed to discriminate, for example, two types of disc not only increases discrimination accuracy but also makes discrimination for specifying many types of disc possible.
The above disc discrimination device is preferably arranged such that light having a different wavelength is individually irradiated from the light irradiation means and the discrimination means discriminates a type depending upon the difference between the reflection factors of the light on the recording surface of the disc based on the quantity of reflected light received and the wavelength of the detection light.
In this case, one piece or one set of light receiving means may be provided, two sets of light sources from which light having different wavelength is individually emitted may be provided with a light emitting unit in adjacent to each other as light irradiation means and the two light sources may be switched so that light is individually emitted therefrom at a different time. Otherwise, it is also possible that a light source having one wavelength and light receiving means are arranged as a set, a light source having another wavelength and the light receiving means are arranged as a set and the light irradiation means and the light receiving means is arranged as an individual set for each wavelength to be used.
Otherwise, detection light including light having a different wavelength is irradiated from the light irradiation means, wavelength separation means for separating the light reflected from the recording surface to a different wavelength is disposed in front of the light receiving means, the light receiving means includes individual light receiving regions for individually receiving the reflected light having the different wavelength and the discrimination means discriminates a type depending upon the difference between the reflection factors of the light on the recording surface of the disc based on the quantities of light received by the respective light receiving regions and the wavelengths of the light applied to the light receiving regions.
The disc discrimination device for discriminating a disc based on the reflection factor of light on a recording surface is prefe
Okada Hirobumi
Togashi Mitsuhiro
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Le Que T.
Luu Thanh X.
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