JPH06267181A - Device for discriminating optical disk - Google Patents

Abstract

PURPOSE:To provide an optical disk discriminating device capable of rapidly discriminating the kind of an optical disk with simple configuration in the optical disk discriminating device, in particular for discriminating the kind of the optical disk. CONSTITUTION:This device is provided with a pickup part 19 irradiating the optical disk with a beam B, receiving the reflected beam modulated by the optical disk 12 and outputting an information signal and a comparator 16 comparing the information signal from the pickup part 19 with a reference signal and comparing the reflectance of the beam B by the optical disk 12 with a reference reflectance, and is constituted by providing a focus detection means detecting the fact that the beam B becomes a focal state to the optical disk 12 and a discriminator 18 discriminating the kind of the optical disk based on a decision signal and a focus detection signal from the comparator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an optical disc discriminating apparatus,
In particular, it relates to a device for discriminating the type of optical disc.

[0002]

2. Description of the Related Art In an optical disc player, for example, a laser disc (hereinafter referred to as "LD") player, L is used.
Information recorded in the LD is read by irradiating the D with a light beam and receiving the reflected light modulated by the LD.

The above LD player only reproduces a normal LD in which information is recorded in advance.
In addition to recording / reproducing for a recordable LD (hereinafter, referred to as “R-LD”) capable of recording arbitrarily according to a user's request, it is also possible to reproduce a normal LD. It is configured to be able to. here,
Since the tracking polarity, the RF gain, the tracking servo loop gain and the like are different between when reproducing the R-LD and when reproducing the normal LD, the disc is the R-LD when reproducing by the recording / reproducing apparatus. It is necessary to determine whether it is a normal LD or a normal LD.

[0004]

When discriminating whether the disc is an R-LD or a normal LD, the user conventionally has to perform the discriminating work, and therefore it takes a long time for the discriminating. Was there. Also, disc size, TOC (Tabl
Although a method for discriminating the disc based on the e of Contents) has been proposed, this system complicates the configuration for discriminating the disc.

An object of the present invention is to provide an optical disc discriminating apparatus which can discriminate the type of an optical disc with a simple structure.

[0006]

According to the present invention, there is provided a pickup unit for irradiating an optical disc with a light beam, receiving reflected light modulated by the optical disc and outputting an information signal, and an information signal from the pickup unit. A comparator for comparing the reflectance of the light beam by the optical disc with the reference reflectance by comparing with the reference signal; focus detection means for detecting that the light beam is in focus on the optical disc; A discriminator that discriminates the type of the optical disc based on the determination signal and the focus detection signal from the comparator.

[0007]

In the present invention, attention is paid to the fact that the reflectance of the light beam differs depending on the type of the optical disc, and the reflectance of the optical beam from the optical disc is compared with the reference signal by comparing the information signal from the pickup unit with the reference signal. And outputs the comparison result. Further, it is detected whether or not the light beam is in focus, considering that the reflected light amount of the light beam is slightly different depending on whether or not the light beam is in focus.
The discriminator discriminates the type of the optical disc based on the comparison result of the reflectance and the focus detection signal.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. First Embodiment FIG. 1 shows the arrangement of an optical disc discriminating apparatus according to the first embodiment of the present invention. In FIG. 1, reference numeral 10 indicates
A spindle motor is shown, and the motor 10 rotates the optical disk 12 in a direction indicated by an arrow A. Optical disc 1
A pickup unit 14 is arranged below 2,
The pickup unit 14 can reciprocate in the radial direction of the optical disk 12, that is, in the direction of arrow B. The pickup unit 14 irradiates the optical disc 12 with a light beam, receives the reflected light modulated by the optical disc 12, and outputs the RF signal 100. This RF signal 100
Is supplied to a demodulator (not shown) and is also supplied to one input terminal of the comparator 16, and the reference voltage V _ref is supplied to the other input terminal of the comparator 16. Focusing on the fact that the reflectance of the light beam differs depending on the type of the optical disc 12, the comparator 16 compares the reflectance of the optical disc 12 with the reference reflectance by comparing the RF signal 100 with the reference voltage V _ref . The discriminator 18 uses the comparator 16
The type of the optical disk 12 is determined based on the determination signal 102 from Hereinafter, the LD will be taken as an example of the optical disc 12, and the comparator 16 and the discriminator 18 will be further described.

First, when the optical disk is a normal LD, the reflectance is high, and the reflectance is 70% and 30 to 35% in the pitless portion and the pitted portion, respectively.
On the other hand, when the optical disc is an R-LD, for example, the recording film is

[0010]

[Equation 1] In the case of R-LD which is, the reflectance is low and the reflectance is
25 for each part without pits and with pits
% And 40%.

Therefore, the comparator 16 sets the reference reflectance to 50.
%, And the reflectance of the optical disk 12 is 50%.
R-L from the comparator 16 when compared with the reference reflectance of
Based on the D / LD discrimination signal 102, the discriminator 18 determines whether the optical disk 12 is an R-LD or a normal LD.

As described above, the optical disc discriminating apparatus according to the first embodiment of the present invention can discriminate the type of the optical disc by comparing the reflectance of the light beam by the optical disc with the reference reflectance. .

FIG. 2 shows an operation flowchart of the optical disc discriminating apparatus according to the first embodiment of the present invention. In FIG. 2, the discriminating operation starts in step 200, inserts an optical disk in step 202, moves the pickup section to the inner mirror section of the optical disk in step 204, and turns on the laser diode in the pickup section in step 206. Start focus. If the focus is not locked in step 208, the process proceeds to step 210, and if the predetermined time (for example, 1.5 seconds) has not elapsed from the focus on in step 210, the process returns to step 208. On the other hand, if a predetermined time has passed after the focus is turned on in step 210, the laser diode is turned off to stop the focus in step 212, and the presence or absence of the disc is determined in step 214.
If there is a disc in step 214, step 21
The disc is ejected at 6, while step 214
If there is no disc at step 218, the operation is stopped at step 218.

On the other hand, when the focus is locked in step 208, the R-LD / LD determination signal is checked in step 220 (see the determination signal 102 in FIG. 1). If the disk is a normal LD in step 220,
In step 222, the disc reproducing operation is started. On the other hand, when the disk is the R-LD in step 220, the tracking polarity inversion, the RF gain, the tracking servo loop gain, and the like are switched in steps 224 and 226, respectively, and then step 22
At 2, the disc playback operation is started. Second Embodiment Next, an optical disc discriminating apparatus according to a second embodiment of the present invention will be described. The second embodiment shows a more specific aspect of the R-LD / LD discrimination in the first embodiment.

FIG. 3 is a diagram showing a configuration of a portion relating to disc discrimination of the optical disc discriminating apparatus according to the second embodiment of the present invention. In FIG. 3, reference numeral 20 indicates an optical pickup, which has a photodiode 21 and a differential amplifier 22. The photodiode 21 has a quadrant photodiode 21c and photodiodes 21a and 21b for tracking control. For pickups such as LD,
Since tracking control is performed by the so-called three-beam method, tracking photodetectors 21a and 21 are provided on both sides of the four-division photodetector 21c as shown in FIG.
b is provided. The outputs of the detectors facing each other of the four-division photo detector 21c are added, and the differential amplifier 2
Entered in 2. The differential amplifier 22 takes the difference between these inputs and inputs it to the zero-cross detector 25 as a focus error signal FE. The zero-cross detector 25 detects the zero-cross point of the input focus error signal as the focused state of the light beam. Note that the above focus control method is already known, and therefore detailed description thereof will be omitted.

On the other hand, the sum signal (α + β) of the outputs of the photo detectors 21a and 21b is input to the comparator 24 via the amplifier 23. This sum signal (α + β) is a signal indicating the amount of light reflected by the optical disc, and the disc type is determined by comparing this value with a reference value. The reference voltage V _ref from the reference voltage generator 27 is applied to the other input terminal of the comparator differential amplifier 24. The reference voltage V _ref is change-controlled by the CPU 26, the details of which will be described later. The comparator 24 compares the reflected light amount (α + β) with the reference voltage V _ref and inputs the comparison result to the zero-cross detector 25. The CPU 26 uses the zero cross detector 25.
The disc discriminating signal is output based on the output signal of.

Next, the details of disc discrimination will be described with reference to FIG.
Will be described with reference to. FIG. 4 shows the relationship between the movement amount of the pickup with respect to the optical disc, the focus error signal FE, and the reflected light amount (α + β). As can be seen from FIG. 4B, the amount of reflected light is R− and
This differs from the case of LD. Discs are discriminated based on this property. As can be seen from FIG. 4A, the same LD or R- is used when the light beam is focused on the disc and when it is not. LD
However, the amount of reflected light is slightly different. That is, as indicated by the reflected light amount curves C ₁ and C ₂ , the reflected light amount is slightly higher in the in-focus state than in the out-of-focus state. This is the same for LD, CD and R-LD. Therefore, for example, if the inserted disc is L
In the case of D, if the light beam is in focus, the reflected light amount value at that time is point A in FIG. 4B, and this is the reference value V _ref1
By comparing with, it is recognized that the inserted disc is LD. However, when the light beam is not in focus, for example, at the point C in FIG. 4B, if the same comparison with the reference value V _ref1 is performed, the actual disc is L
Despite being D, the amount of reflected light does not exceed the reference value V _ref1 and therefore may be erroneously recognized as R-LD. In order to prevent such erroneous recognition, comparison of the reflected light amounts may be performed under the condition that the light beam is within the focus pull-in range shown in the drawing, and optimally in the completely focused state.

For the above reasons, in this embodiment, the amount of reflected light of the inserted disc is compared with the reference value, the focus state of the light beam is detected, and the disc is discriminated based on both conditions. Do. The reference values V _ref1 and V _ref2 can be arbitrarily determined in relation to the reflected light amount curves C ₁ and C ₂ , but the reference value is set relatively high with respect to the reflected light amount curve to focus the light beam. If the comparison is performed in the state, the probability of erroneous recognition is reduced, and reliable discrimination is possible.

The specific operation of this embodiment will be described below with reference to FIG. First, when the disc is inserted, the pickup is moved to the inner circumference of the disc (steps 200-204). Here, the laser diode is turned on, focus control is started, and it is determined whether or not the focus system is locked, that is, whether or not the light beam is in focus (steps 204-206). This is specifically determined by whether or not the zero-cross point of the focus error FE signal is detected by the zero-cross detector 25. When the light beam is in focus, the reflected light amount (α + β) is compared with the reference value V _ref1 for the LD (step 320). That is, the zero-cross detector 25 is
When the focused state of the light beam is detected, the comparison result of the comparator 24 is supplied to the CPU 26. When the reflected light amount (α + β) is larger than the reference value V _ref1 , the inserted disc is an LD, a CD, etc., so that the process proceeds to step 328 and reproduction is started.

On the other hand, the reflected light amount (α + β) is the reference value V _ref1.
When it is smaller, the reflected light amount is (α + β) R−L
It is determined whether or not it is larger than the reference value V _{ref2 in} the case of D (step 322). The amount of reflected light (α + β) is the reference value V
If it is larger than _ref2 , the inserted disc is RL
Since it is D, the polarity of tracking is reversed (step 324) and the RF gain is switched (step 32).
6) Then, reproduction is started (step 328). On the other hand, when the amount of reflected light is smaller than the reference value V _ref2 in step 322, the disc is out of the standard range of the reproducing apparatus, and the disc is ejected (step 31).
6).

If the focus is not locked in step 308, the process proceeds to steps 310-318, but since these are the same as steps 210-218 of the first embodiment, the description thereof will be omitted (see FIG. 2). .

In the above description, the amount of reflected light is compared with the reference value after the focus lock is detected, but this order can be reversed. The operation in this case is shown in FIG.

As described above, the amount of reflected light is different between the case of LD or the like and the case of R-LD, and in the case of R-LD, the level of the amount of reflected light should not exceed the LD reference value V _ref1 . In reality, due to scratches on the disk surface and other factors, R
The reflectance of the LD may change and exceed the reference value for the LD. Therefore, first, the amounts of reflected light are compared, and it is inspected whether or not the focus is locked on the disc judged to be LD. Even if the amount of reflected light of the R-LD changes due to the scratches and other factors as described above, and the disc is misrecognized, such a disc does not lock the focus due to scratches or the like. Therefore, the above-mentioned erroneous recognition of the disk can be corrected by further detecting the focus lock after the determination by comparing the reflected light amounts.

In this case, the reference values V _ref1 and V _ref2 shown in FIG. 4 (B) are set lower than those in the case where the focus lock is detected first (the curve C _{1 of the} reflected light amount, to C _2, by setting to) be low, it is possible to prevent erroneous determination as described above.

Referring to the flowchart of FIG. 6, after the disc is inserted, a predetermined initial operation is performed (steps 400 to 406), and the LD reference value V _ref1 is set (step 408). Next, it is determined whether the amount of reflected light exceeds the reference value V _ref1 (step 410). If it exceeds the limit, focus pull-in is started (step 41).
2) It is judged whether or not it is locked (step 41).
4). If the focus is locked, the inserted disc is an LD, and the reproduction is started. On the other hand, if the focus is not locked, the operation is stopped after a predetermined time has elapsed and the disc is ejected (steps 416-42).
0).

When it is determined in step 410 that the reference value V _ref1 is not exceeded, the reference value is changed to the reference value V _ref2 of the R-LD, and the focus gain and the like are changed (step 422). The amount of reflected light is compared with the reference value V _ref2 (step 242). If it exceeds the reference value V _ref2 , focus pull-in is started and it is detected whether or not the focus is locked (steps 426-428). When the focus is locked, the disc is RL
Since it is D, the tracking is reversed, the RF gain is changed, etc. (steps 430-432), and the reproduction is started. On the other hand, if the focus is not locked, the same error processing as in steps 416-420 is performed (step 434).

[0027]

As described above, according to the present invention,
Since the type of optical disc is determined using the focus state of the light beam and the reflectance of the light beam by the optical disc,
Optical discs can be quickly discriminated with a simple configuration.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of an optical disc discriminating apparatus according to a first embodiment of the present invention.

FIG. 2 is an operation flowchart of the optical disc discriminating apparatus according to the first embodiment of the present invention.

FIG. 3 is a structural explanatory view of an optical disc discriminating apparatus according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between a position of a pickup, a reflected light amount, and a tracking error signal.

FIG. 5 is an operation flowchart of the optical disc discriminating apparatus according to the second embodiment of the present invention.

FIG. 6 is another operation flowchart of the optical disc discriminating apparatus according to the second embodiment of the present invention.

[Explanation of symbols]

 10 ... Spindle motor 12 ... Optical disk 14 ... Pickup section 16, 24 ... Comparator 18 ... Discriminator 20 ... Pickup 21 ... Photodiode 22, 23 ... Differential amplifier 25 ... Zero cross detector 26 ... CPU 27 ... Reference voltage generator 100 ... RF signal 102 ... R-LD / LD discrimination signal

Claims (1)

[Claims] 1. A pickup unit for irradiating an optical disc with a light beam, receiving reflected light modulated by the optical disc, and outputting an information signal, and comparing the information signal from the pickup unit with a reference signal, A comparator for comparing the reflectance of the light beam from the optical disc with a reference reflectance, focus detection means for detecting that the light beam is in focus on the optical disc, a determination signal from the comparator and a focus An optical disc discriminating apparatus comprising: a discriminator that discriminates a type of an optical disc based on a detection signal.