JP4097833B2 - Disc discriminating method and optical disc recording / reproducing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical disc recording / reproducing apparatus such as a DVD player, and more particularly to a disc discriminating method for discriminating the type of disc to be recorded / reproduced.
[0002]
[Prior art]
Conventionally, there are a CD-ROM drive, a DVD-ROM drive, a CD player, a DVD player, a video CD player, and the like as the optical disk reproducing device. These players determine, for example, whether the disk to be reproduced is a CD or a DVD, Based on this determination, the disc is reproduced.
[0003]
First, when discriminating the disc, a disc 1 to be discriminated is irradiated with a laser beam from a pickup 2 as shown in FIG. 4, and the pickup 2 is moved from the top to the bottom by an actuator (not shown) or from the bottom to the top. Move to. At this time, if the disc 1 is a single layer DVD disc, an SBAD (sub-beam addition) signal and an FE (focus error) signal as shown in FIGS. 5A and 5B can be obtained.
[0004]
5C and 5D show the SBAD signal and FE signal of the dual layer DVD disc, and FIGS. 5E and 5F show the SBAD signal and FE signal of the CD disc.
[0005]
Here, the peak of the signal indicated by (1) in FIG. 5 is a reflected signal due to reflection when the focal point of the laser light hits the surface of the disk 1. Further, (2) is a zero cross point of the FE signal, and shows the focus point of the laser beam when the focal point of the laser beam hits the pit surface of the disk 1.
[0006]
By the way, according to the disc standard, in the case of a DVD disc, the distance from the surface to the focus point is 0.570 mm for a single layer disc, 0.550 mm for a dual layer disc, and in the case of a CD disc. , 1.2 mm.
[0007]
Therefore, in the prior art, the time between the vertex of the reflected signal (1) of the SBAD signal and the zero cross point (2) of the FE signal in FIG. 5 is measured to discriminate the CD / DVD disc.
[0008]
That is, the time from the reflected signal (1) to the zero cross point (2) in FIG. 5 is different between the DVD disk and the CD disk, and the CD disk is longer than the DVD disk. Is being determined.
[0009]
If the disc 1 is discriminated as a DVD disc, whether the disc is a single layer disc or a dual layer disc is discriminated by the number of focus points of the FE signal shown in FIGS. 5B and 5D, and there is one focus point. Is discriminated as a single layer disc, and when there are two focus points, it is discriminated as a dual layer disc.
[0010]
[Problems to be solved by the invention]
In the conventional disc discriminating method of the optical disc reproducing apparatus, the time from the reflection point (1) of the SBAD signal to the FE signal focus point (2) in FIG. 5 is the moving speed of the pickup, that is, the sensitivity of the actuator that moves the pickup, Since variations occur depending on the control voltage and current, the time difference for discriminating between the DVD disc and the CD disc varies. When the variation in the time difference becomes large, there is a problem in that the disc is erroneously discriminated and the disc discriminating rate is lowered.
[0011]
The above problem occurs not only in the optical disk reproducing apparatus but also in an optical disk recording apparatus that records data on the disk after determining the type of the disk.
[0012]
The present invention has been made in order to solve the above-described conventional problems. The purpose of the present invention is to discriminate disc types that can always discriminate disc types accurately regardless of actuator sensitivity, control voltage, and current. Method and an optical disc recording / reproducing apparatus using the determination method.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, a feature of the invention of claim 1 is that a disc discriminating method for discriminating the type of the optical disc when data is recorded or reproduced by irradiating the optical disc with a laser beam from the pickup. A reflected signal which is a peak signal of an SBAD (sub-beam addition) signal indicating that the laser beam is focused on the surface of the optical disc when the pickup is moved in a direction perpendicular to the optical disc while irradiating the laser beam. And first and second peak signals of an FE (focus error) signal appearing before and after the laser beam is focused on the pit surface of the optical disc, and a first time between the reflected signal and the first peak signal is measured. The second time between the first and second peak signals is obtained, and the ratio of these times is calculated. Is to determine the type of the optical disc by the ratio calculation.
[0014]
According to the first aspect of the present invention, the first time between the reflected signal and the first peak signal differs depending on the type of the optical disc, but the second time between the first and second peak signals hardly changes. Therefore, for example, the value of the first time / second time varies depending on the type of the optical disk. Therefore, by obtaining this value, the type of the optical disk can be specified.
[0015]
A feature of the invention of claim 2 resides in that the type of the optical disc is discriminated based on a value obtained by dividing the first time by the second time.
[0016]
A feature of the invention of claim 3 is that, instead of obtaining the second time between the first and second peak signals, two regions formed between the waveforms of the first and second peak signals and a reference voltage line. And the sum of the areas of these two regions is used instead of the second time.
[0017]
A feature of the invention of claim 4 is that it is discriminated whether it is a single layer disc or a dual layer disc based on the number of zero cross points or peak points indicating that the focus of the laser beam is focused on the pit surface of the optical disc. .
[0018]
According to a fifth aspect of the present invention, there is provided an optical disc recording / reproducing apparatus for recording or reproducing data by irradiating a laser beam from a pickup onto an optical disc, wherein the pickup is perpendicular to the optical disc while irradiating the laser beam from the pickup. And a reflected signal which is a peak signal of an SBAD (sub-beam addition) signal indicating that the laser beam is focused on the surface of the optical disc during the movement of the pickup and the laser beam is a pit surface of the optical disc. Means for measuring first and second peak signals of an FE (focus error) signal appearing before and after focusing on the first time, a first time between the measured reflected signal and the first peak signal, and the first Means for obtaining a second time between the second peak signals and calculating a ratio of these times Is to and means for discriminating the type of the optical disc by the ratio calculation.
[0019]
A feature of the invention of claim 6 is that, instead of obtaining the second time between the first and second peak signals, two regions formed between the waveforms of the first and second peak signals and a reference voltage line. And the sum of the areas of these two regions is used instead of the second time.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a first embodiment of an optical disk recording / reproducing apparatus of the present invention. The disc discriminating system of the optical disc recording / reproducing apparatus includes a pickup 2 that irradiates the disc 1 with laser light, a signal processing unit 3 that processes a signal obtained from the pickup 2 and generates an FE (focus error) signal and an SBAD signal. An A / D conversion unit 4 that converts an analog signal such as an FE signal or an SBAD signal obtained from the signal processing unit 3 into a digital signal, and a digitized FE signal or SBAD that is input from the A / D conversion unit 4 The disc discrimination processing unit 5 discriminates the type of the disc 1 based on the signal.
[0021]
The system control unit 6 performs recording / reproduction control and the like, but performs recording or reproduction control corresponding to the type of the set disc based on the discrimination result of the disc discrimination processing unit 5.
[0022]
Next, the operation of the present embodiment will be described. During disc discrimination, the pickup 2 moves in a direction perpendicular to the disc 1 by an actuator (not shown) while irradiating the disc 1 with laser light. At this time, the signal obtained from the pickup 2 is processed by the signal processing unit 3 to generate an FE signal and an SBAD signal. These signals are digitized by the A / D conversion unit 4 and input to the disc discrimination processing unit 5. The
[0023]
The disc discrimination processing unit 5 performs disc 1 discriminating processing described below from the input FE signal and SBAD signal, and gives the result to the system control unit 6.
[0024]
First, the pickup 2 is moved from the top to the bottom or from the bottom to the top while irradiating the disc 1 with laser light from the pickup 2 as described above.
[0025]
Thereby, the SBAD signal as shown in FIG. 2A and the FE signal as shown in FIG. 2B are obtained. However, the peak of the signal (1) is a reflection signal due to reflection when the focal point of the laser light hits the surface of the disk 1. The zero-cross point of the FE signal is the focal point of the laser beam when the focal point of the laser beam hits the pit surface of the disk 1, that is, the focus point of the laser beam. 3) appears.
[0026]
Therefore, the disk discrimination processing unit 5 measures the time from the vertex of the reflected signal (1) of the SBAD signal in FIG. 3 to the vertex of the peak signal (2) of the FE signal to obtain (4). Further, the time from the peak of the peak signal (2) of the FE signal in FIG. 2 to the peak of the peak signal (3) appearing in reverse is measured and is set as (5).
[0027]
Thereafter, the ratio of (4) / (5) is calculated, and the type of the disk 1 is determined based on the ratio calculation result. That is, the ratio calculation result is greater when the disk 1 is a CD disk than when it is a DVD disk. This is because the length of (4) varies depending on the type of the disc 1 (the CD is longer), but the length of (5) hardly changes. As a result, the disc discrimination processing unit 5 can discriminate the type of the disc 1.
[0028]
According to the present embodiment, since the type of the disk 1 is determined based on the ratio calculation result of (4) / (5), the sensitivity, control voltage, and current of the actuator that moves the pickup 2 vary. In some cases, (4) and (5) vary, but the ratio of (4) / (5) is almost constant. Thus, in this example, the type of the disk 1 can always be accurately discriminated regardless of the sensitivity of the actuator, the control voltage, and the current.
[0029]
In this example as well, after disc 1 is discriminated as a DVD disc, it is discriminated whether it is a single layer disc or a dual layer disc by the number of zero cross points of the FE signal obtained (or the number of peak points of the FE signal). ing.
[0030]
FIG. 3 is a signal waveform diagram showing the main part of the second embodiment of the optical disk recording / reproducing apparatus of the present invention. This example is different from the previous embodiment only in the method for obtaining the peak-to-vertex time of the peak signals (2) and (3) appearing in the FE signal, and the configuration of the apparatus is the same as the previous embodiment. In the following description, the configuration of FIG. 1 is borrowed.
[0031]
Also in disc discrimination in this example, the pickup 2 is moved from top to bottom or from bottom to top while irradiating the disc 1 with laser light from the pickup 2. As a result, the SBAD signal and the FE signal as shown in FIG.
[0032]
Thereafter, the time from the vertex of the reflected signal (1) of the SBAD signal in FIG. 3 to the vertex of the peak signal (2) of the FE signal is measured, and this is defined as (4). Also, the area of the hatched portion surrounded by the FE signal reference voltage and the FE signal peaks (2) and (3) in FIG. 4 is measured at regular intervals to be (6).
[0033]
Next, the ratio calculation of (4) / (6) is performed, and the type of the disk 1 is determined based on the result.
[0034]
Here, (6) which is the area of the hatched portion surrounded by the FE signal reference voltage and the FE signal in FIG. 3 is a value proportional to the time from the peak to the peak of the peak signals (2) and (3) of the FE signal. I know that will be.
[0035]
Accordingly, the ratio calculation result of (4) / (6) obtained using the area (6) of the hatched portion is also larger when the disc 1 is a CD than when it is a DVD. As a result, the disc discrimination processing unit 5 can discriminate the type of the disc 1.
[0036]
In this embodiment as well, when the sensitivity, control voltage, and current of the actuator vary, (4) and (6) vary, but the ratio of (4) / (6) becomes almost constant. The same effect as the embodiment can be obtained.
[0037]
The SBAD signal is always obtained when the three-beam pickup 2 is used, but even when the one-beam pickup 2 is used, a signal equivalent to the SBAD signal is obtained. The same effect can be obtained by applying the disc discrimination method.
[0038]
In the above embodiment, the signal obtained from the pickup 2 is A / D converted and the disc is discriminated digitally. However, the disc discriminating method of the present invention is combined with the first and second embodiments. It can also be realized with an analog circuit.
[0039]
【The invention's effect】
As described above in detail, according to the present invention, by determining the value used for disc discrimination by ratio calculation, the disc type can always be discriminated accurately regardless of actuator sensitivity, control voltage, and current. Can do.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a first embodiment of an optical disc recording / reproducing apparatus of the present invention.
FIG. 2 is a signal waveform diagram illustrating a disc discrimination method in the apparatus shown in FIG.
FIG. 3 is a signal waveform diagram showing a main part of a second embodiment of the optical disc recording / reproducing apparatus of the present invention.
FIG. 4 is a diagram for explaining a conventional disc discrimination method.
FIG. 5 is a signal waveform diagram illustrating a conventional disc discrimination method.
[Explanation of symbols]
1 Disc 2 Pickup 3 Signal Processing Unit 4 A / D Conversion Unit 5 Disc Discrimination Processing Unit 6 System Control Unit

Claims (6)

In a disc discrimination method for discriminating the type of the optical disc when data is recorded or reproduced by irradiating the optical disc with laser light from a pickup,
Moving the pickup in a direction perpendicular to the optical disc while irradiating laser light from the pickup;
A reflected signal which is a peak signal of an SBAD (sub beam addition) signal indicating that the laser beam obtained at that time is focused on the surface of the optical disc and an FE (focus error) which appears when the laser beam is focused on the pit surface of the optical disc. ) Measure the first and second peak signals of the signal,
Obtaining a first time between the reflected signal and the first peak signal and a second time between the first and second peak signals, and calculating the ratio of these times;
A disc discriminating method characterized in discriminating the type of the optical disc from the ratio calculation result. In a disc discrimination method for discriminating the type of the optical disc when data is recorded or reproduced by irradiating the optical disc with laser light from a pickup,
Moving the pickup in a direction perpendicular to the optical disc while irradiating laser light from the pickup;
A reflected signal which is a peak signal of an SBAD (sub beam addition) signal indicating that the laser beam obtained at that time is focused on the surface of the optical disc and an FE (focus error) which appears when the laser beam is focused on the pit surface of the optical disc. ) Measure the first and second peak signals of the signal,
Obtain a first time between the reflected signal and the first peak signal and an area of two regions formed between the waveform of the first and second peak signals and a reference voltage line, and calculate the ratio of these times,
A disc discriminating method characterized in discriminating the type of the optical disc from the ratio calculation result.   3. The disc discriminating method according to claim 1, wherein the type of the optical disc is discriminated based on a value obtained by dividing the first time by the second time.   4. A disc according to claim 1, wherein the disc is discriminated as a single layer disc or a dual layer disc based on the number of zero cross points or peak points indicating that the focal point of the laser beam is focused on the pit surface of the optical disc. Disc discriminating method described in 1. In an optical disk recording / reproducing apparatus for recording or reproducing data by irradiating a laser beam from a pickup onto an optical disk,
Means for moving the pickup in a direction perpendicular to the optical disc while irradiating laser light from the pickup;
Before and after the reflected signal which is the peak signal of the SBAD (sub beam addition) signal indicating that the laser beam is focused on the surface of the optical disc and the laser beam is focused on the pit surface of the optical disc while the pickup is moving. Means for measuring first and second peak signals of an FE (focus error) signal appearing in
Means for obtaining a first time between the measured reflected signal and the first peak signal and a second time between the first and second peak signals and calculating a ratio of these times; and the ratio calculation result Means for discriminating the type of the optical disc by:
An optical disc recording / reproducing apparatus comprising: In an optical disk recording / reproducing apparatus for recording or reproducing data by irradiating a laser beam from a pickup onto an optical disk,
Means for moving the pickup in a direction perpendicular to the optical disc while irradiating laser light from the pickup;
Before and after the reflected signal which is the peak signal of the SBAD (sub beam addition) signal indicating that the laser beam is focused on the surface of the optical disc and the laser beam is focused on the pit surface of the optical disc while the pickup is moving. It means for measuring a first, second peak signal FE (Four Kasuera) signal appearing on,
A first time between the measured reflected signal and the first peak signal and an area of two regions formed between the waveform of the first and second peak signals and a reference voltage line are obtained. An optical disk recording / reproducing apparatus comprising: means for calculating a ratio; and means for determining the type of the optical disk based on the result of the ratio calculation.

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