JP3316416B2 - Optical disc playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk reproducing apparatus, and more particularly to an optical disk reproducing apparatus capable of changing a linear velocity according to vibration of the apparatus.

[0002]

2. Description of the Related Art The speed at which a commercially available optical disc reproducing apparatus can operate is increasing year by year. In the case of a CD-ROM device for a personal computer, the speed is changed from the standard speed to double speed, quadruple speed, six times speed,. . It is rising to say, and CD-ROM
Many of the devices are capable of selectively operating at one of a plurality of linear velocities.

[0003] The rotational speed of a disk increases with linear velocity. The rotation speed on the inner peripheral side is about 500 rpm in the case of the standard speed (x1), but is 3000 rpm in the case of x6.
m. As the speed increases, vibration also increases, which is a problem. When the vibration increases, the signal reading may be affected and reading may not be possible. Causes of the vibration include eccentricity of the disk, variations in the position where the disk is held, and unevenness in the thickness of the disk. For example, a commercially available CD-ROM disc having a nominal thickness of 1.2 mm has a difference between the maximum thickness and the minimum thickness of 0.1 mm.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical disk reproducing apparatus capable of performing reading reliably and operating at a maximum speed.

[0005]

According to the present invention, there is provided an optical disk reproducing apparatus comprising: means for rotating an optical disk; means for detecting vibration or impact of the apparatus during rotation of the optical disk;
The data in the TOC area of the optical disk is read at a predetermined rotational speed, and thereafter, the rotational speed of the disk is changed to determine a rotational speed at which vibration or impact does not become excessive based on the output of the detecting means. Control means for controlling the rotation speed of the optical disk based on the result and reading the data in the data area.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention.

[0007] The CD-ROM device of this embodiment is a CD-ROM device.
A spindle motor 2 for rotating the ROM disk 1 is provided. The CD-ROM disk 1 stores data representing characters, sounds, images, and the like in spiral tracks. On the innermost side of the disk, there is a TOC (table of contents) area in which addresses and the like of respective data are stored. The data representing the characters, sounds, images, and the like are stored in a data area located outside the TOC area.

The objective lens 4 converges a laser beam from a laser diode (not shown) to form a beam spot on the surface of the disk. Data on the disk is read at the position of this beam spot. Objective lens 4
Also receives the reflected light from the disk 1 and focuses /
It is led to the tracking control circuit 11.

The focus unit 5 has a focus coil 6 and a focus magnet 7. The lens 4 is supported by a lens support 4s. The focus coil 6 is supported by the lens support 4s, and is thus fixed to the lens 4. The focus magnet 7 is held by a pickup frame (indicated by a dotted line PU). The focus coil 6 and the focus magnet 7 are opposed to each other, and cooperate with each other to move the lens 4 closer to or away from the surface of the disk according to a focus control signal supplied from the focus / tracking control circuit 11. In the focus direction.

[0010] The tracking section 8 has a tracking coil 9 and a tracking magnet 10. The tracking coil 9 is supported by the lens support 4 s, and as a result, is fixed to the lens 4. The tracking magnet 10 is held by a pickup frame PU. The tracking coil 9 and the tracking magnet 10 face each other, cooperate with each other, and move the lens 4 in the radial direction of the disk, that is, in the tracking direction according to the tracking control signal supplied from the focus / tracking control circuit 11. move.

Focus / tracking control circuit 11
Detects a focus error and a tracking error based on light reflected from the disk, supplies a focus control signal to the focus unit 5, and supplies a tracking control signal to the tracking unit 8. The focus / tracking control circuit 11 also outputs a reproduction signal RS from the disk 1.

The motor control 3 controls the rotation speed of the spindle motor 2 in synchronization with the clock included in the reproduction signal RS from the disk 1. The rotation control is a control for CLV (constant linear velocity). As the beam spot from the objective lens 4 moves to the outside of the disk (for scanning along a track), the rotational speed decreases and the linear velocity decreases. Keep constant. The device has several different linear velocities, x1, x2, x
4, x6, x8 speed mode (x1 represents standard speed,
x2, x4, x6 and x8 are twice the standard speed, respectively.
Doubling, 6 times, and 8 times). In each speed mode, the rotation speed changes in the following range. x1 530-200 rpm x2 1060-400 rpm x4 2120-800 rpm x6 3180-1200 rpm x8 4240-1600 rpm One feature of this embodiment is performed immediately after the disc is inserted (each time the disc is performed). In the operation in the test mode, vibration and impact (expressed by acceleration) are detected, and above that, a limit rotational speed at which vibration or impact becomes excessive is determined.

In the operation of the reproduction mode for reproducing the data of the disc, which is performed after the test mode, the linear velocity is controlled so that the rotational speed does not exceed the limit rotational speed.
The linear velocities that can be selected are discrete values (x1, x2, x
4,. . . ), And the control is performed as follows. That is, the beam spot moves outward in the radial direction,
When the rotational speed reaches a position where the rotational speed does not exceed the limit rotational speed even when the linear speed is switched to a higher value, the linear speed is switched to the higher value.

A means for detecting vibrations and shocks is provided in order to find a limit rotational speed at which vibrations and shocks become excessive when the rotation speed exceeds the limit.

In the present embodiment, vibrations and shocks are detected when the beam spot is on the innermost side and the disk is rotating at each of various linear velocities. If the vibration and the shock are not excessive at a certain linear velocity, and the vibration or the shock is excessive at one higher linear velocity, the vibration or the impact corresponds to the linear velocity (when the beam spot is on the innermost peripheral side). Let the rotation speed be the limit rotation speed.

If the vibration and impact are not excessive at the highest linear velocity (x8), the rotational velocity corresponding to the linear velocity (x8) (when the beam spot is on the innermost peripheral side) is defined as the limit rotational velocity. .

The means for detecting vibration and shock will be described below.

An electromotive force is induced in the focus coil 6 by the relative displacement between the focus coil 6 and the focus magnet 7 due to the vibration. In this embodiment, the vibration is detected by using the electromotive force.

Similarly, an electromotive force is induced in the tracking coil 9 in accordance with the relative displacement between the tracking coil 9 and the tracking magnet 10. In this embodiment, the vibration is detected using the electromotive force.

The shock sensor 17 is fixed to the pickup frame PU and detects the acceleration of the pickup frame PU.

The system control circuit 13 includes a microprocessor, and controls each unit of the apparatus according to a program written in the ROM 14. In particular, the electromotive force generated by the focus unit 5 and amplified by the focus amplifier 15, the electromotive force generated by the tracking unit 8 and amplified by the tracking amplifier 16, and the detection signal from the shock sensor 12 Specify the linear velocity.

The RAM 17 stores data necessary for the operation of the system control circuit 13. This includes threshold values for the electromotive force representing the signal and the acceleration representing the shock (if exceeded, the vibration or shock is judged to be excessive), and the vibration and shock should not exceed any of the threshold values For this reason, data representing a critical rotational speed at which the rotational speed should not be exceeded is included.

The focus switch 18 is controlled by the system control circuit 13 to connect the focus unit 5 to the focus / tracking control circuit 11 to enable focus control or to connect to the system control circuit 13 via the focus amplifier 15. To enable detection of vibration.

The tracking switch 19 is controlled by the system control circuit 13 to connect the tracking section 8 to the focus / tracking control circuit 11 to enable tracking control, or to connect to the system control circuit 13 via the tracking amplifier 16. To enable detection of vibration.

FIG. 2 shows the operation of the system control circuit performed according to the program stored in the ROM 14.

When it is detected that the disc 1 has been inserted into the apparatus (S1), the focus switch 18 and the tracking switch 19 fall to the contacts 18a and 19a, and
Connected to the focus / tracking control circuit 11 to enable focus control and tracking control (S
2).

The linear velocity is set to the standard velocity, and data in the TOC area is read (S3, S4). Since the data in the TOC area is important as initial data, the speed is set to the standard speed instead of the 8 × speed.

Next, the focus switch 18 is set to the contact 18b.
The tracking switch 19 is tilted to the contact 19b and connected to the tracking amplifier 16 (S5). The beam spot is maintained on the innermost circumference of the disk. The system control circuit 13 increases the linear velocity of the disk 1 by 8 times the motor control circuit 3).
Is instructed to ascend (S6). No control signal is given to the focus coil 6 and the tracking coil 9, an electromotive force due to vibration is supplied to the system control circuit 13 via the focus amplifier 15 and the tracking amplifier 16, and information on acceleration from the shock sensor 12 is controlled by the system control. The signal is supplied to the circuit 13 (S7).

As described above, the RAM 17 stores the threshold values for the electromotive force from the focus amplifier 15, the electromotive force from the tracking amplifier 16, and the output from the shock sensor 12. If there is an input exceeding any of the threshold values, it is determined that there has been vibration or shock exceeding the limit (S8). Next, in step S9, it is determined whether the linear velocity has already reached (decreased to) the standard velocity (x1). If the speed is already at the standard speed, the speed cannot be further reduced. Therefore, a display indicating that vibration or impact is excessive at the standard speed is displayed (S11), and the operation is terminated. If the speed is not the standard speed in step S9, then in step S10, the speed is reduced by one step (for example, from x8 to x6) (S1
0). Vibration and impact are reduced due to the reduced speed.

After reducing the speed, the test is again performed for vibration and shock. If the vibration or shock is still above the threshold, reduce the speed again. For example, it is reduced from x6 to x4. Similarly, the speed is reduced by one step, for example, from x4 to x2 and from x2 to x1 until the vibration and the impact become smaller than the threshold values (S7 to S10).

When the vibration and the shock are no longer excessive (in S8,
Yes), the rotation speed at which the vibration and impact are not excessive for the first time in the above operation (the rotation speed when the beam spot is on the innermost side at the set linear speed) is the limit rotation. The speed is stored in the RAM 17 (S12).

Further, in this step S12, a radial position of the disk whose rotational speed does not exceed the limit rotational speed even when the linear speed is switched to a higher value by one step is obtained, and the address of the track or sector at that position is stored in the RAM 17. Let it.

For example, if the linear velocity at which the vibration and impact do not become excessive when the beam spot is on the innermost side is x1, the limit rotation speed is 530 rpm. A position at which the rotational speed reaches (decreases to) the limit rotational speed at another linear speed is determined. In this case such a position only exists if the speed is x2. The address of the track or sector at this position is stored in the RAM 17.

Next, in step 12, the focus switch 18 and the tracking switch 19 are connected to the contacts 18a and 1
9a side, focus / tracking control circuit 1
1 to perform focus control and tracking control.

As described above, each time a disk is inserted, vibration and impact are detected. During data reproduction from the disk, the linear velocity is controlled so that the rotational speed does not exceed the limit rotational speed.

FIG. 3 shows the operation of the control circuit according to the program stored in the ROM 14. This operation is performed when data on the disk is reproduced after setting the limit rotation speed.

As described above, the disk 1 is rotating at a constant linear velocity, and therefore the rotational speed decreases as the beam spot moves radially outward. For example, the range of the change in the rotation speed between the double speed and the standard speed is as follows. Standard speed (x1): 530-200 rpm Double speed (x2): 1060-400 rpm The maximum rotation speed at the standard speed is higher than the minimum rotation speed at the double speed. Therefore, at x2, the rotation speed when the radial position of the beam spot is outside a certain position (the position where the rotation speed is 530 rpm at x2) is lower than the maximum rotation speed at the standard speed. A similar relationship exists between x4 and x2, x6 and x4, and x8 and x6.

The motor control circuit 3 has a capturing range of about ± 50%. For example, even if the rotation speed is doubled by switching from the standard speed to the double speed, for example, from 250 rpm to 500 rpm, the speed before the switching is -50% of the speed after the switching and is within the capturing range. Therefore, data can be read continuously (without interruption).

As described above, the track or sector address at a position where the linear velocity can be switched to a higher value without affecting data reading for each linear velocity is stored in the RAM1.
7 is stored. When the beam spot reaches this position during the reproduction of data from the disk, the linear velocity is switched to a value one step higher (S21 to S29). Then, reading is continued. This increases the average speed of reading data and ensures correct reading.

In the above embodiment, the focus unit 5, the tracking unit 8, and the impact sensor 12 are used. It is not necessary to use all three. For example, only one of these may be used. However, if both the means for detecting the vibration based on the electromotive force from the focus unit 5 and the means for detecting the vibration based on the electromotive force from the tracking unit 8 are used, the vibration in the direction perpendicular to the disk surface and the vibration in the radial direction Can be detected separately, and can be detected with different sensitivities and characteristics.

The detection of vibrations can also be detected in other ways, for example using existing components already forming part of the device.

[0042]

In the above embodiment, when the beam spot is located on the innermost peripheral side and the linear velocity is decreased one step at a time, the rotational speed at the time when it is first determined that vibration and impact are not excessive is limited. The rotation speed was used.

The limit rotational speed can be determined in consideration of a margin from the threshold values of vibration and shock when it is first determined that the vibration and shock are not excessive.

For example, it is assumed that the vibration or impact close to the threshold is a predetermined ratio (for example, M = 20%) with respect to the threshold. At this time, the linear velocity is x1, and the beam spot is also on the innermost side, so that the rotation speed is 530 rpm
m. In this case, the limit rotation speed is 530 / (1-M / 100) = 530 / 0.8 = 6
62.5 rpm. In this case, the position at which the linear velocity is switched to a higher value is such that the rotational speed after the switching is 662.5 rp.
m.

In the above embodiment, when the beam spot is on the innermost peripheral side of the disk and the linear velocity is lowered one step at a time, the rotational speed (for example, 530 rpm) when the vibration or impact is not excessively large first is set. The limit rotation speed was set.

Instead of or in addition to the above, a value (for example, 500 rpm) that is somewhat lower than the speed (530 rpm) at that time may be used as the limit rotation speed. This value is hereinafter referred to as a secondary limit rotational speed. For the sake of distinction, the first limit rotational speed is referred to as a primary limit rotational speed.

The secondary limit rotational speed is used for determining the switching position. The reason for using such a secondary limit rotational speed is to provide an operation margin.

That is, the system control circuit 13 calculates the linear velocity x
At 1 only, rotation at 530 rpm is permitted, and at other linear velocities, the rotation speed is controlled to be 500 rpm or less.

In the above embodiment, the beam spot was fixed on the innermost side of the disk, the connection was switched step by step, and the rotation speed was also switched between discrete values. Instead, the rotation speed is changed continuously or substantially continuously (that is, the beam spot is on the innermost side and the linear speed is discontinuous (x1, x2, x4,...).
Irrespective of the rotation speed at that time). Then, the maximum rotation speed at which both the vibration and the impact are equal to or less than the respective thresholds is found, and this maximum rotation speed may be set as the limit rotation speed.

In order to find such a maximum rotation speed, the rotation speed is gradually reduced from the highest value, and the speed at the time when the vibration or impact is not excessively large at first is set to the above-mentioned maximum speed, that is, the limit speed. good. Alternatively, such a maximum speed may be found by a binary search method.

To obtain the maximum speed by gradually lowering the speed, the same operation as in FIG. 2 may be performed. However, instead of step S10 (the linear velocity is reduced by one step), the rotational speed is reduced by a predetermined unit amount.

In the above embodiment, the maximum linear velocity is x8. However, the present invention is not limited to this. The present invention
The present invention can also be applied to an optical disk reproducing device that can operate at a higher linear velocity.

[0054]

According to the present invention, since the vibration is detected and the rotation speed of the disk is set based on the vibration, the disk can be rotated at an allowable rotation speed according to the disk to be used.

[0055]

[0056]

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main part of a CD-ROM reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a control operation.

FIG. 3 is a flowchart showing a control operation in the same manner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 CD-ROM disk 2 Spindle motor 4 Lens 5 Focusing part 8 Tracking part 12 Shock sensor 13 System control circuit 18 Focus switch 19 Tracking switch

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Masayuki Hayashida 3-201 Minamiyoshikata, Tottori City, Tottori Prefecture Tottori Sanyo Electric Co., Ltd. (72) Inventor Akihiro Kishishita 3-201 Minamiyoshikata, Tottori City, Tottori Prefecture Tori Tori Sanyo Electric Co., Ltd. (72) Inventor Kiyoshi Kotani 3-201 Minamiyoshikata, Tottori City, Tottori Prefecture Tottori Sanyo Electric Co., Ltd. (56) References JP-A-8-55422 (JP, A)

Claims (1)

(57) [Claims] A means for rotating an optical disk;
Means for detecting vibration or impact of the device during rotation of the disk
A predetermined rotation of the data in the TOC area of the optical disc.
Read processing by speed, and then turn the disk
The rotational speed is changed to reduce vibration based on the output of the detection means.
Or the rotation speed at which the impact does not become excessive,
Controlling the rotation speed of the optical disk based on the
It is characterized by comprising control means for reading area data
Optical disk playback apparatus according to.