JPH1186302A - Disc playback apparatus and focus control method for disc playback apparatus - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To increase the access speed of a CD player or the like without deteriorating the accuracy of focus control during normal reproduction and when moving a sled of an optical pickup. SOLUTION: An equalizer amplifier 21 which amplifies a focus error signal FE and supplies the same as a focus drive signal FD to a focusing actuator is connected to first and second changeover switches 23 and 24 in parallel with each other via the switches. 1st and 2nd equalizer amplifier 21
a and 21b. The gain of the first equalizer amplifier 21a is set to a gain suitable for reproduction, and the gain of the second equalizer amplifier 21b is set to a higher gain than during reproduction. When the sled of the optical pickup is moved, the first and second changeover switches 23 and 24 are operated by the sled signal SL from the system control circuit, and the second equalizer amplifier 21b is operated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a disk reproducing apparatus such as a CD player for reading and reproducing information from a disk on which information is recorded, and a focus control method in the disk reproducing apparatus.

[0002]

2. Description of the Related Art Conventionally, in a disk reproducing apparatus such as a CD player, recorded data is reproduced by moving an optical pickup in a radial direction of a disk while rotating a compact disk (CD) or the like. The optical pickup irradiates the disk with laser light, detects reflected light thereof, and reads data from the disk. A focus lens that focuses the laser light on the recording surface of the disk, and a focus lens in the optical axis direction And a focusing actuator for adjusting the position.
In the disc reproducing apparatus, the focusing actuator is driven by a drive signal that changes according to a focus error signal generated in response to the detection of the reflected light, so that the laser beam is always focused on the recording surface of the disc. Focus servo for driving the lens is performed.

In a disk reproducing apparatus, when the sled of the optical pickup is moved, for example, when a disk is set, the innermost TOC (Table of Content) of the disk is set.
s) When moving the optical pickup in the radial direction of the disc when sending the optical pickup until it enters the area (thread-in) or when searching for data such as music selection, by performing it at high speed, the desired data can be obtained. It is possible to access immediately. Note that, even when the sled moves, the above-described focus servo is always in the ON state for track count and quick data reading near the target.

[0004] In recent years, among disc reproducing apparatuses, especially those dealing with a CD-ROM on which image data, program data, and the like are recorded, the quadruple speed,
At present, access speeds are increasing, such as 8 × speed, 16 × speed, and so on.

[0005]

However, if the access speed is increased as described above, the speed of the optical pickup at the time of moving the sled is also increased. The impact is increased, and the influence of the vibration generated in the optical pickup (more specifically, the focus lens), that is, the shake in the tracking direction or the surface shake is increased. Accordingly, even if the above-described focus servo is performed, the accuracy of focus control during movement of the sled is reduced, and the focus is easily shifted, so that a data reading error is likely to occur. Along with this, there also arise problems such as a longer convergence time to the target position on the inner peripheral side of the disk.

On the other hand, in order to solve such a problem, the rate of change of the drive signal which changes in accordance with the focus error signal, that is, the focus gain may be increased, but in this case, it is difficult to defocus once the focus has been adjusted. However, conversely, since it is difficult to adjust the focus from a state where the focus is shifted, there is a problem that ideal focus control cannot be performed during normal reproduction.

The present invention has been made in view of such a conventional problem, and enables an increase in access speed without deteriorating the accuracy of focus control during normal reproduction and movement of a sled of an optical pickup. An object of the present invention is to provide a disk reproducing apparatus and a control method thereof.

[0008]

According to a first aspect of the present invention, there is provided an optical pickup for reading information from a disk on which information is recorded, and a focus provided on the optical pickup. In a disc reproducing apparatus that adjusts the position of a lens in the optical axis direction by an actuator driven by a drive signal that changes in accordance with a focus error signal, and focuses a laser beam on the disc, when the sled of the optical pickup is moved, A drive signal supply means for supplying a drive signal having a larger change rate than the time to the actuator is provided.

In such a configuration, when the sled of the optical pickup is moved, the drive signal supply means supplies the actuator with a drive signal having a larger change rate than during reproduction. For this reason, when the sled is moved, the actuator adjusts the position of the focus lens by the drive signal having a large change rate, so that the focus of the laser beam once adjusted is less likely to be deviated even if the sled movement speed is high. In addition, during normal reproduction, the actuator adjusts the position of the focus lens with a drive signal smaller than the rate of change at the time of moving the sled, so that it is possible to perform ideal focus control in which laser light once shifted is easily focused.

[0010] In addition, in the invention of claim 2,
The drive signal supply means includes a first signal generation means for generating a drive signal having a change rate during reproduction, and a drive signal having a change rate larger than a gain of the drive signal generated by the first signal generation means. A second signal supply unit for generating a drive signal to be supplied to the actuator when the optical pickup is moving a sled;
From the drive signal generated by the signal generation means of
Switching means for switching to the drive signal generated by the signal generation means.

In such a configuration, two types of drive signals having different rates of change supplied to the actuators during reproduction and when the sled is moved are individually generated by the first and second signal generation means. For this reason, the rate of change of the drive signal generated by the second signal generation means can be made compatible with a plurality of devices in which the vibration of the optical pickup generated when the sled moves is different.

Further, in the invention according to claim 3, the drive signal supply means generates the drive signal having a frequency characteristic according to a frequency of the focus lens in a tracking direction, and generates the drive signal of the optical pickup. When the sled is moved, the drive signal having a frequency characteristic whose change rate in the determined frequency band is larger than that at the time of reproduction is generated.

In this configuration, the frequency band is set to the frequency band of the vibration generated in the focus lens during the movement of the sled, so that the laser light once adjusted once during the movement of the sled is less likely to be out of focus. At the time of reproduction, ideal focus control that makes it easy to focus the laser light once shifted can be performed.

According to a fourth aspect of the present invention, there is provided an optical pickup for reading information from a disk on which information is recorded, and a focus lens provided on the optical pickup is changed according to a focus error signal. In a focus control method of a disc reproducing apparatus for adjusting a position in an optical axis direction by an actuator driven by a drive signal and focusing a laser beam on the disc,
When the sled of the optical pickup is moved, a drive signal having a higher rate of change than during reproduction is supplied to the actuator to adjust the position of the focus lens.

In such a method, when the sled is moved, the laser light after the laser beam is once focused is less likely to be defocused, and the accuracy of the focus control when the sled moving speed is increased is not reduced. Ideal focus control can be performed without making it difficult to focus once the state has shifted.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a drive system and a control system of a CD player according to the present invention. That is, the CD player includes a loading motor 2 for loading and unloading the disk 1, a spindle motor 3 for rotating the disk 1, an optical pickup 4 for reading data recorded on the disk 1, and moving the optical pickup 4 in the radial direction of the disk 1. Slide motor 5 for
And The optical pickup 4 is movably supported by a rail (not shown) extending in the radial direction of the disk. The optical pickup 4 includes a laser diode, a focus lens 6 for focusing laser light on the recording surface of the disk 1 (see FIG. 2), and a focusing actuator 7 for adjusting the position of the focus lens in the optical axis direction (see FIG. 2). ,
A tracking actuator for adjusting the position of the focus lens 6 in the radial direction, and a photodetector for detecting light reflected from the disk 1 and transmitted through the semi-cylindrical lens by a photodiode having a light-receiving surface divided into four parts. It is something.

The rotation of the disk 1 and the operation of the optical pickup 4 are controlled by a system control circuit 10, an RF signal processing circuit 11, a digital signal processing circuit 12, an APC
(Automatic Power Control) circuit 13, focus servo circuit 14, tracking servo circuit 15, spindle servo circuit 16, and traverse servo circuit 17. The system control circuit 10 includes a CPU (not shown), a ROM storing various data such as an operation program of the CPU, a RAM serving as a working memory of the CPU, a data input / output circuit, and the like. Control a series of operations. Note that various operation keys and indicators are connected to the system control circuit 10.

The RF signal processing circuit 11 amplifies the detection signal detected by the optical pickup 4, that is, the four detection signals A / B / C / D and the like by the photodetector described above. Focus error signal FE (FE = (A + C)-(B + D)),
A tracking error signal or the like is generated (see FIG. 2). The digital signal processing circuit 12 includes an RF signal processing circuit 11
While identifying the synchronization signal from the detection signal amplified by the above, data and control signals are extracted and demodulated. The demodulated data is output as a digital signal,
The signal is output to an analog signal processing circuit (not shown). The APC circuit 13 detects a change in the amount of laser light with the optical pickup 4, and controls the current flowing through the laser diode so that the amount of laser light is always constant.

The focus servo circuit 14 is a drive signal supply means of the present invention, and as shown in FIG.
Equalizer amplifier 2 connected to F signal processing circuit 11
1 and a driver 22 connected to the focusing actuator 7. The equalizer amplifier 21 is an active filter for stabilizing the focus servo loop system shown in FIG. 2, and is generated by the RF signal processing circuit 11 from the detection signals A / B / C / D of the optical pickup 4. Focus error signal F
A focus drive signal FD that changes according to E is generated and applied to the focusing actuator 7 via a driver 22 to achieve the phase compensation.

As shown in FIG. 3, the equalizer amplifier 21 includes first and second changeover switches 23 and 24 provided on the RF signal processing circuit 11 side and the driver 22 side, respectively, which are interlocked with each other. The first equalizer 21a and the second equalizer 21b are provided in parallel between the RF signal processing circuit 11 and the driver 22 via the two changeover switches 23 and 24. The first equalizer 21a is set so that the DC gain of the focus drive signal FD, that is, the focus gain is set to a gain suitable for normal time (at the time of reproduction), and the second equalizer 21b has
The focus gain is set to be higher than normal (at the time of reproduction). The first and second changeover switches 23 and 24 are switching means of the present invention, and a first equalizer 21 a is provided between the RF signal processing circuit 11 and the driver 22 in a normal state (during reproduction). On the other hand, the second equalizer 21 is connected according to an input of a thread signal SL from a system control circuit 10 described later.
b operates between the RF signal processing circuit 11 and the driver 22.

The tracking servo circuit 15 drives the tracking actuator based on the tracking error signal and controls the focus lens 7 of the optical pickup 4 in the radial direction of the disk 1. The spindle servo circuit 16 includes a system control circuit 10
The disk 1 is constantly rotated at a constant linear velocity (CLV) from the inner circumference to the outer circumference based on the control signal from the spindle motor 3.
The traverse servo circuit 17 controls the driving of the sled motor 5, and moves the entire optical pickup 4 outward following the track. Further, based on the thread signal SL sent from the system control circuit 10, when the disc 1 is set, the optical pickup 4 is sent (thread-in) until the innermost TOC area is entered, and further at the time of music selection (at the time of search). , The optical pickup 4 is jumped and moved to a target track. That is, the thread is moved.

In this embodiment having the above configuration, during normal reproduction, the first equalizer 21a is in a functioning state in the focus servo circuit 14;
A focus gain suitable for reading data can be obtained. As a result, ideal focus control accuracy that can easily focus the laser light once shifted is obtained. Further, when the optical pickup 4 moves the sled, the focus servo circuit 14 controls the first and second changeover switches 2.
When the second and third equalizers 21b operate instead of the first equalizer 21a, the focus gain is switched to a higher gain than during reproduction. For this reason, the sled movement is performed at high speed, and even if the impact on the optical pickup 4 is large at the movement start timing or the brake timing, the focus of the laser light once adjusted is hard to be deviated, and the precision of the focus control may be reduced. Can be prevented. Therefore, the access speed can be increased without lowering the accuracy of focus control during normal reproduction and when the optical pickup 4 moves the sled.

Also, in the present embodiment, 2
Since the first and second equalizer amplifiers 21a and 21b individually generate the different types of drive signals, the change rate of the drive signal generated by the second equalizer amplifier 21b depends on the vibration of the optical pickup generated when the sled moves. A plurality of devices can be supported.
Therefore, the versatility can be given to the equalizer amplifier 21, and the circuit configuration is simple and the design is easy.

FIG. 4 is a circuit diagram according to a second embodiment of the present invention. That is, this circuit is another circuit used as the equalizer amplifier 21 in FIG. 2, and the optical pickup 4 of the thread signal SL sent from the system control circuit 10
The first and second diodes D1 and D2 to which a signal SL + for moving the optical pickup 4 in the outer peripheral direction of the disk 1 and a signal SL + for moving the optical pickup 4 in the outer peripheral direction of the optical disc 4 are input respectively, and the RF signal processing is performed. The first resistor R to which the focus error signal FE sent from the circuit 11 is input
0, the driver 22 receives the focus drive signal FD
, The second to fourth resistors R1 to R3,
First and second capacitors C1 and C2, transistor Q
It is constituted by.

Then, similarly to the circuit shown in FIG.
A focus drive signal FD that changes according to the focus error signal FE generated by the signal processing circuit 11 is generated and output to the driver 22. The frequency characteristic is that when the inputs of the first and second diodes D1 and D2 are both "L", that is, at the time of normal reproduction, the transistor Q is turned on, and the first characteristic shown in FIG.
Characteristic a of the first or second diode D1, D2
When one of the inputs is “H”, that is, when the optical pickup 4 moves the sled, the transistor Q is turned off, and as shown in FIG. Specifically, the gain of the frequency band L of the vibration generated in the focus lens 7) is set to be the second characteristic b which is larger than the first characteristic a.

Therefore, also in the present embodiment, at the time of normal reproduction, an ideal focus control accuracy that can easily focus the laser light once shifted is obtained. In addition, when the optical pickup 4 moves the sled, even if the impact on the optical pickup 4 is large at the movement start timing or the brake timing, the focus of the laser light once adjusted is hardly defocused, and the precision of the focus control is prevented from being reduced. it can. Therefore, similar to the first embodiment,
The access speed can be increased without lowering the accuracy of focus control during normal reproduction and when the optical pickup 4 moves the sled.

Further, in the present embodiment, since the same effect as that shown in the first embodiment can be achieved by the single equalizer amplifier 21, the individual devices have the same format when moving the sled. It is convenient to set the change rate of the drive signal FD supplied to the caching actuator 7 to a change rate most suitable for the frequency of the focus lens 6.

In the above description, the present invention is applied to a CD.
Although only the case where the present invention is applied to a player has been described, similar effects can be obtained by using the present invention in other disk reproducing devices such as a laser disk (LD) player, a DVD player, a CD-ROM drive device, and the like. .

[0029]

As described above, according to the first and fourth aspects of the present invention, when the sled of the optical pickup is moved, a drive signal having a higher rate of change than during reproduction is supplied to the actuator. Even when the speed is high, it is possible to perform ideal focus control in which once the laser light is once focused is less likely to be defocused when the sled is moved, and it is easier to focus the laser light once shifted during normal reproduction. Therefore, it is possible to increase the access speed without reducing the accuracy of focus control during normal reproduction and when moving the sled of the optical pickup.

In addition to the above, in the invention of claim 2,
Two types of drive signals having different rates of change supplied to the actuator at the time of reproduction and at the time of sled movement are individually generated by the first and second signal generators, and the rate of change of the drive signal generated by the second signal generator is generated. Can be adapted to a plurality of devices having different vibrations of the optical pickup generated when the sled moves. Therefore, the drive signal supplier can be provided with versatility, and the configuration is simple and the design becomes easy.

According to the third aspect of the present invention, the frequency band of the vibration generated in the focus lens when the sled moves is set, so that the laser light once adjusted is less likely to be out of focus during the sled movement, and the normal reproduction is performed. In some cases, it is possible to perform ideal focus control that makes it easy to focus a laser beam that is once shifted. Therefore, the effect described above can be obtained by a single drive signal supply unit. Also, it is convenient to set the rate of change of the drive signal supplied to the actuator when the sled moves to the most suitable rate for the frequency of the focus lens during the sled movement for each device.

[0032]

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main part of a CD player according to the present invention.

FIG. 2 is a block diagram showing a focus servo loop of the CD player.

FIG. 3 is a circuit diagram illustrating an equalizer amplifier according to the first embodiment of the present invention.

FIG. 4 is a circuit diagram showing an equalizer amplifier according to a second embodiment of the present invention.

FIG. 5 is a characteristic diagram showing a change in gain with respect to the frequency of the equalizer amplifier.

[Explanation of symbols]

 Reference Signs List 1 disc 4 optical pickup 5 slide motor 6 focus lens 7 focusing actuator 14 focus servo circuit 21 equalizer amplifier 21a first equalizer amplifier 21b second equalizer amplifier

Claims (4)

[Claims] 1. An optical pickup for reading information from a disk on which information is recorded, wherein a focus lens provided on the optical pickup is driven by an actuator driven by a drive signal that changes in response to a focus error signal. A disc reproducing apparatus for adjusting a position in a direction to focus a laser beam on the disc, comprising: a drive signal supply unit for supplying, when the sled of the optical pickup is moved, a drive signal having a higher rate of change than during reproduction to the actuator. A disk reproducing apparatus characterized by the above-mentioned. 2. The method according to claim 1, wherein the drive signal supply means generates a drive signal having a change rate at the time of reproduction, and a change rate of the drive signal generated by the first signal generation means, which is higher than a gain of the drive signal. A second signal generating means for generating a large drive signal, and a second signal generating means for generating a drive signal to be supplied to the actuator when the optical pickup is moved from a drive signal generated by the first signal generating means. 2. The disk reproducing apparatus according to claim 1, further comprising: a switching unit configured to switch to a drive signal generated by: 3. The drive signal supply unit generates the drive signal having a frequency characteristic according to a frequency of the focus lens in a tracking direction, and generates a drive signal in a predetermined frequency band when the optical pickup moves a sled. 2. The disk reproducing apparatus according to claim 1, wherein the drive signal having a frequency characteristic whose change rate is larger than that at the time of reproduction is generated. 4. An optical pickup for reading information from a disk on which information is recorded, wherein a focus lens provided on the optical pickup is driven by an actuator driven by a drive signal that changes according to a focus error signal. In a focus control method of a disc reproducing apparatus that adjusts a position in a direction and focuses a laser beam on the disc, when the sled of the optical pickup is moved, a drive signal having a higher rate of change than at the time of reproduction is supplied to the actuator. A focus control method for a disk reproducing apparatus, comprising: adjusting a position of a focus lens.