JPH06309778A - Reproducing device for optical information - Google Patents

Abstract

PURPOSE:To prevent a recordable disk from being recorded by reproducing power by discriminating a kind of a disk by a reflection factor of light for a disk and controlling a disk device in accordance with a kind of a disk. CONSTITUTION:When an output of a tilt sensor 3 is larger than a prescribed value, a detecting circuit 8 discriminates it as an exclusive reproducing disk based on an output of a differential amplifier 7, when an output of the tilt sensor 3 is smaller than the prescribed value, the circuit 8 discriminates it as a recordable disk. When it is discriminated as a recordable disk, each servo gain is adjusted to a recording disk. Next, in order to prevent disappearance of information written in the disk, after the disk is rotated, a semiconductor laser LD is turned on, and a focus servo routine is performed.

Description

Detailed Description of the Invention

[0001]

The present invention relates to an LDR (Laser Disk
Recordable disc and LD-ROM
The present invention relates to an optical information reproducing apparatus represented by an optical disk player (LD player) capable of reproducing both read-only disks such as (Laser Disk-Read Only Memory).

[0002]

2. Description of the Related Art Conventionally, there has been no so-called compatible LD player capable of reproducing both a recordable disc and a reproduction-only disc.

Generally, in the case of an LD player, one of the tilt sensor outputs for tilt detection of the disk is used to detect the disk, and when a disk is present, the focus actuator is moved up and down to output the sum of the focus. Activates the focus servo when exceeds the specified value,
After confirming the focus servo operation, rotate the disc. In the case of the LD, the disc may be significantly curved or may be in the shape of a potato chip, so that the disc and the pickup may be extremely separated from each other in the initial state. Therefore, in the case of the LD, the focus servo is first applied and then other operations are performed.

On the other hand, OMDD (Optical Memory Disk Dr)
In the case of ive), VDR (Vidio Disk Recorder), etc., the disk is stored in the case in advance, and a disk type detection hole is provided outside the case. The playback device
After detecting the hole for detecting the type of the disk, the disk is rotated, the semiconductor laser is turned on, and finally the focus servo is operated.

[0005]

However, OMDD, V
Disc specifications are strictly regulated in DR, etc.,
This is rare in the case where the disc and the pickup are significantly separated from each other as in the LD. Further, if the semiconductor laser is turned on and the focus servo is operated while the disc is stationary, there is a risk that the disc will be recorded with reproduction power. In particular, in the case of a disc having excellent recording sensitivity even at a high linear velocity such as LDR, if focus is set in the disc stationary state, recording may be performed even with low reproduction power.

An object of the present invention is to provide a so-called compatible type optical information reproducing apparatus which detects the type of a disc and controls the operation of the disc device according to the type.

[0007]

An optical information reproducing apparatus according to the present invention is an optical information reproducing apparatus for reproducing a recordable disc and a reproduction-only disc, and detects the reflectance of light to the disc, When the reflectance indicated by the detection signal is a predetermined value or less, the disc is rotated first, then the light source for detecting optical information is turned on, and then And a control means for controlling the focus servo to operate.

[0008]

According to the above-mentioned structure of the present invention, the reflectance of the light with respect to the disk is detected by the detector, and the detection signal indicating the reflectance is supplied to the controller. The control means determines that the disc is recordable and reproducible when the reflectance indicated by the detection signal is less than or equal to a predetermined value,
First, the disk is rotated, then the light source for detecting optical information is turned on, and then the focus servo is controlled to operate. Thus, by discriminating the type of the disc by the reflectance of the light to the disc and controlling the optical information reproducing device according to the disc type, it is possible to provide a so-called compatible type optical information reproducing device. .

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a circuit diagram of an optical information reproducing apparatus according to the present invention. In the circuit diagram, LED (Light Emitting)
The light beam emitted from the diode) 1 is reflected by the disk 2, and its reflectance is detected by the tilt sensors 3 and 4. The output of the tilt sensor 3 is connected to the inverting input terminal of the operational amplifier 5 via the resistor R ₁ and also to the inverting input terminal of the differential amplifier 9. The output of the operational amplifier 5 is connected to the presence / absence detection circuit 6 of the disk and also to the inverting input terminal of the differential amplifier 7 via the resistor R ₅ . On the other hand, the reference voltage V ₀ set by the resistor R ₄ is connected to the non-inverting input terminal of the differential amplifier 7 via the resistor R _6, and the output of the differential amplifier 7 is connected to the disc type detection circuit 8. To be done. Further, the output of the tilt sensor 4 is connected to the non-inverting input terminal of the differential amplifier 9, and the output of the differential amplifier 9 is connected to the distance measuring circuit 10 between the disc and the tilt sensor. The detection circuit 6,
The detection circuit 8 and the measurement circuit 10 are respectively connected to the microcomputer 11, and the output of the microcomputer is connected to each servo.

Next, the operation of the optical information reproducing apparatus shown in FIG. 1 will be described. The tilt sensor 3 supplies the detection signal indicating the detected reflectance to the inverting input terminal of the differential amplifier 9 and also to the inverting input terminal of the amplifier 5 via the resistor R ₁ . The detection signal amplified by the amplifier 5 is supplied to the disk presence / absence detection circuit 6, and the detection circuit 6 supplies a signal a indicating the presence / absence of the disk to the microcomputer 11. The detection signal amplified by the amplifier 5 is also supplied to the inverting input terminal of the differential amplifier 7 via the resistor R ₅ . On the other hand, the reference voltage V ₀ set by the resistor R ₄ is applied to the resistor R _{4 at} the non-inverting input terminal of the differential amplifier 7.
Supplied via ₆ . The differential amplifier 7 is the operational amplifier 5
Output of the tilt sensor 3 and the reference voltage V amplified by
The difference output from ₀ is supplied to the disc type detection circuit 8. Here, the reference voltage V ₀ serves as a threshold value for detecting the type of disk. In addition, the experiment shows that the reflectance is 40%.
Is suitable for identifying the type of disc. The detection circuit 8 supplies a signal b for identifying the disc type to the microcomputer 11. Further, the tilt sensor 4 supplies a detection signal indicating the detected reflectance to the non-inverting input terminal of the differential amplifier 9, and the differential amplifier 9 outputs the output thereof to the circuit 10 for measuring the distance between the disc and the tilt sensor. The distance measuring circuit 10 supplies the signal c indicating the distance to the microcomputer 11. The microcomputer 11 uses the signals a, b, c
Based on the above, each servo system 12 is controlled. First Embodiment FIG. 2 shows a flowchart of a first embodiment of the startup operation of the compatible player of the recordable disc and the read-only disc. First, the disk presence / absence detection circuit 6
It is determined whether the output of the tilt sensor 3 is present (step 21). That is, if the output of the tilt sensor 3 is present, it is determined that the disc is present (step 2).
If the output of the tilt sensor 3 does not exist, it is determined that the disk does not exist (step 21, NO). When it is determined that the disc exists (step 21, YES), the disc type detection circuit 8
Determines the disc type. That is, the differential amplifier 7
At, the output of the tilt sensor 3 amplified by the operational amplifier 5 is a predetermined value V ₀ set by the resistor R ₄ .
(Step 22). Based on the output of the differential amplifier 7, the detection circuit 8 determines that the disc is a read-only disc when the output of the tilt sensor 3 is larger than a predetermined value (step 22, YES), and when it is smaller than the predetermined value. Disc is a recordable disc (step 2)
2, NO). When it is determined that the disc is a reproduction-only disc (step 22, YES), each servo gain (focus, tracking, sum signal, tilt output, RF amplifier gain, etc.) is adjusted to the reproduction disc (step 23),
Enter the focus servo routine. In the focus servo routine, move the objective lens up and down (step 2
7) Scan the focus zero point. That is, the point at which the focus sum signal exceeds a predetermined value is scanned (step 2
8) At the time when the value exceeds the predetermined value (step 28, YE
S), close the focus servo (step 2)
9). Next, after confirming that the focus servo is closed, the disk is rotated (step 30) and the next operation is performed.

On the other hand, when it is determined that the disc is a recordable disc (step 22, NO), each servo gain is adjusted to the recording disc (step 24). Next, in order to prevent the destruction of the information written on the disc, the disc is rotated (step 25), the semiconductor laser LD is turned on (step 26), and then the focus servo routine is started. The operation of the focus servo routine is similar to that of the read-only disc. First, the objective lens is moved up and down (step 27 ') to scan the focus zero point. That is, the point at which the focus sum signal becomes equal to or larger than the predetermined value is scanned (step 28 '), and when it becomes equal to or larger than the predetermined value (step 28', YES), the focus servo is closed (step 29 ').

In some cases, the focus servo may be difficult to close when the disc is rotating because the distance between the disc and the pickup at the time of start-up is too large. In such a case, the distance measuring circuit 1 between the disc and the tilt sensor
At 0, the distance between the disc and the pickup is detected from the output difference of the tilt sensors 3 and 4 output from the differential amplifier 9, and the pickup is moved in the radial direction when the distance is more than a certain distance (or constant). In the case of the distance tilt servo mechanism, the entire pickup is moved up and down). As described above, the operation of FIG. 2 is started after confirming that the distance between the disk and the pickup is within a certain range so that the focus servo can be closed stably even while the disk is rotating. Second Embodiment FIG. 3 shows a flowchart of a second embodiment of the startup operation of the compatible player of the recordable disc and the read-only disc. In the first embodiment, the output of the tilt sensor is used to measure the reflectance of light with respect to the disc, but in the second embodiment, the focus S-shaped peak-to-peak is measured.
Measure peak power. The focus S-shaped peak-to-peak output is proportional to the reflectance of light on the disc. That is, in the first embodiment, the reflectance of light that was directly measured using the output of the tilt sensor is indirectly measured using the focus S-shaped output in the second embodiment.

In FIG. 3, the objective lens is moved up and down (step 31), the focus S-shaped peak-to-peak value is measured (step 32), and the S-shaped peak-to-peak value is read-only type disc. It is determined whether there is any (step 33). That is, S-shaped peak toe
If the peak value is larger than the predetermined value, it is determined to be a read-only type disc (step 33, YES), and if it is smaller than the predetermined value, it is determined to be a recordable type disc (step 33, NO). If the disc is determined to be a read-only type disc (step 33, YES), each servo gain is adapted to the read-only disc (step 3).
3 '), after turning on the LD (step 34), the focus servo is closed (step 35) and the disc is rotated (step 36). On the other hand, when it is determined that the type is the recordable type (step 33, NO), each servo gain is adapted to the recordable disc (step 37),
After rotating the disk (step 38), the LD is turned on (step 39) and the focus servo is closed (step 40). Third Embodiment FIG. 4 is a diagram showing the relationship between the recording speed and the linear velocity of CDR and LDR. In the case of a CDR disc that can be played by a general CD player, the disc will not be recorded unless there is a power of 5 mW even at a linear velocity of 0 m / sec (the disc is in a stationary state). Even if the disc is rotated after the focus servo operation, the recorded information is recorded. It will not be destroyed. But,
On an LDR disk or the like which has excellent recording sensitivity even at a high linear velocity, recording may be performed at a low recording power even at a considerably low linear velocity. A method of distinguishing a disc capable of recording with such a low recording power from a read-only disc will be described below. At this time, it is used that the spectral reflectances of aluminum (playback-only type disk) and dye disk (recordable disk) are different for light of a specific wavelength.

FIG. 5 shows the spectral reflectances of a read-only type disc (aluminum disc) and a recordable disc (dye disc). Generally, in the case of a recordable disc (dye disc) that has a sensitivity at 780 nm (wavelength used for recording) and can obtain a certain reflectance after recording,
The reflectance is considerably smaller than that of a read-only type disc (aluminum disc) near 660 nm. In this way, the read-only type disc can be distinguished from the dye type disc by detecting the two reflectances. The wavelength of the LED for disc identification is not limited to 660 nm, and it is preferable to select the optimum one according to the type of disc.

FIG. 6 shows a flowchart of the third embodiment of the startup operation of the compatible player of the recordable disc and the read-only disc. In FIG. 6, first, 6
The output of the 60 nm LED sensor is detected (step 4
1). Next, when the output of the 660 nm LED sensor is larger than the predetermined value (step 41, YES), it is determined that the disc is a read-only disc (aluminum disc) as described with reference to FIG. 5, and the LD is turned on first. (Step 42), the focus servo is closed (step 43), and then the disc is rotated (step 4).
4).

On the other hand, when the output of the LED sensor having a wavelength of 660 nm is small (step 41, NO), it is determined that the recording disk (pigment disk), each servo gain is adapted to the recording disk (step 45), and the disk is rotated first. After that (step 46), the LD is turned on (step 47) and the focus servo is closed (step 48).

[0017]

According to the above-described structure of the present invention, the disc type can be discriminated by the reflectance of light to the disc, and the disc device can be controlled according to the disc type. That is, when the reflectance of the light is less than or equal to a predetermined value, it is determined that the disc is recordable and reproducible, first the disc is rotated, then the light source for detecting optical information is turned on, and then the focus servo is turned on. It can be controlled to operate. In this way, it is possible to prevent the recordable disc from being recorded with the reproducing power and provide a so-called compatible type optical information reproducing apparatus.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an optical information reproducing apparatus according to the present invention.

FIG. 2 is a flowchart showing a first embodiment of a startup operation of a compatible player of a recordable disc and a reproduction-only disc.

FIG. 3 is a flowchart showing a second embodiment of the startup operation of the compatible player of the recordable disc and the reproduction-only disc.

FIG. 4 is a diagram showing a relationship of recording power with respect to linear velocities of CDR and LDR.

FIG. 5 is a diagram showing the spectral reflectances of a read-only type disc and a dye disc.

FIG. 6 is a flowchart showing a third embodiment of the startup operation of the compatible player of the recordable disc and the reproduction-only disc.

[Explanation of symbols]

 1 ... Light emitting diode 2 ... Disk 3, 4 ... Tilt sensor 5 ... Amplifier 6 ... Disk presence / absence detection circuit 7 ... Differential amplifier 8 ... Disk type detection circuit 9 ... Differential amplifier 10 ... Distance measuring circuit 11 ... Microcomputer 12 ... Each servo

Claims (1)

[Claims] 1. An optical information reproducing apparatus for reproducing a recordable disc and a reproduction-only disc, the detecting device detecting a reflectance of light with respect to the disc, and outputting a detection signal indicating the reflectance. When the reflectance indicated by the detection signal is less than or equal to a predetermined value, first the disc is rotated, then the light source for detecting optical information is turned on, and then the focus servo is controlled to operate. An apparatus for reproducing optical information, which is provided.