JP3125514B2 - Optical disk tilt control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tilt control device for an optical disk used for a CD player, a video disk and the like.

[0002]

2. Description of the Related Art When playing back an optical disk such as a video disk, the optical disk bends at the outer periphery. Therefore, when playing back the outer periphery of the optical disk, an inclination occurs between the optical disk and an optical pickup for playing back the optical disk. The quality of the product deteriorates.

Conventionally, in order to prevent the reproduction signal from deteriorating due to the tilt of the optical disk, the signal is read by tilting the objective lens with respect to the tilt of the optical disk.

A conventional optical disc tilt control apparatus is described in, for example, Japanese Patent Application Laid-Open No. 1-263951. According to Japanese Patent Application Laid-Open No. 1-263951, the inclination of the disk 5 is detected by the two-divided photodetectors 21a and 21b, and the objective lens 4 is tilted by the coil 33 that drives the tilt of the objective lens 4 about the center of gravity 40 of the movable part 10 as the rotation center. Let's go to disk 5
Was corrected.

[0005]

However, in such a conventional configuration, if the tilt of the optical disk is corrected by tilting the objective lens, the drive center of the drive unit for the objective lens and the focus of the objective lens are different. When tilted, there is a problem that the reproduction position on the optical disk is shifted.

An object of the present invention is to provide a control apparatus for tilting an optical disk which solves the above-mentioned problems and can maintain a reproduction position even when an objective lens is tilted.

[0007]

In order to achieve this object, a tilt control device for an optical disk according to the present invention adds a signal input to a tilt drive device for tilting an objective lens to a translation drive device for translating the objective lens. The configuration is such that a reproduction position shift which is inputted and deviated by an inclination driving device of an objective lens is compensated for by a translational motion by a translation driving device.

[0008]

With the tilt control device for the optical disk, the reproducing position shifted by the tilting motion of the objective lens can be compensated by the translational motion, so that the position on the optical disk where the objective lens reproduces can be maintained at a constant position before and after tilting. You can do it.

[0009]

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 first embodiment of an optical disc tilt control device according to the present invention.

In FIG. 1, reference numeral 1 denotes an optical disk;
Is an objective lens. The objective lens 3 is a light condensing means of an optical pickup (not shown) for reproducing information on the optical disk 1, and reproduces information while moving various controls by moving an objective lens movable section 10 for holding the objective lens 3. are doing.

The objective lens movable section 10 has a degree of freedom to move in the direction perpendicular to the surface of the optical disk 1 for focusing on the optical disk 1, and also adjusts the reproduction position in the radial direction of the optical disk 1, so-called tracking. The optical disc 1 has a degree of freedom that allows translation along the radial direction. Further, the objective in order to follow the bending of the radial direction of the optical disk 1, the degree of freedom that can be inclined in the radial direction and having both, the current applied to a coil placed in a magnetic field, respectively for the three or more degrees of freedom The lens 3 can be driven in each degree of freedom.

Each coil is driven by a coil and a magnetic field (not shown) for each degree of freedom. In this description, each coil is referred to as a vertical drive 11, a translation drive 12, and a tilt drive 13 Will be referred to by different names.

The optical pickup detects an error signal for controlling in a vertical direction and an error signal for controlling in a translation direction. In particular, the signal of the translational position error is shown as the tracking error signal 20.

Reference numeral 14 denotes an inclination detector for detecting a relative inclination between the objective lens 3 and the optical disk 1, an inclination control circuit 15 for frequency-processing the output of the inclination detector 14, and an inclination driving circuit for supplying a current to the inclination driving device 13. A feedback circuit is formed by inputting the signal to the inclination driving device 13 through the line 16.

The translation of the objective lens movable unit 10 is controlled by a translation control circuit 21 for frequency-processing the tracking error signal 20 output from the optical pickup and a translation drive circuit 22 for supplying a current to the translation drive unit 12. The signal is input to the driving device 12 to form a feedback circuit.

The adder 23 adds the drive signal of the tilt drive device 13 input to the tilt drive circuit 16 and the drive signal of the translation control device 21 input to the translation drive circuit 22 to add the translation drive device 12. To input current.

The tilt drive unit 13 tilts the objective lens movable unit 10 in the radial direction of the optical disk 1. As shown in FIG. 2, the playback position of the objective lens 3 on the optical disk 1 and the objective lens movable unit When the objective lens 3 is inclined along the arrow A and the objective lens 30 is inclined, the reproduction position of the optical disc 1 is shifted.

In FIG. 1, when this displacement occurs, the translation drive unit 12 attempts to return the original lens to the reproduction position by moving the objective lens movable unit 10 by the feedback circuit. If this occurs, the translation drive device 12 cannot follow, and the control of tracking loss occurs.

In order to prevent this, according to the present invention, the adder 2
3, a signal input to the tilt driving device 13 is added and input to the translation driving device 12 to correct the positional shift of the objective lens 3 caused by the tilt.

In this manner, as shown in FIG. 3, when the objective lens 3 is tilted along the arrow A and the objective lens 31 is tilted, the objective lens 3 translates in the direction of the arrow B, and The displacement can be suppressed and corrected, and in combination with the feedback circuit for controlling the translation drive device 12 in FIG. 1, the reproduction position of the optical disc 1 due to the tilt can be kept at a constant position, and the control can be performed. The stability can be improved.

[0021]

[0022]

[0023]

[0024]

Next, a second embodiment will be described. FIG. 4 is a circuit diagram of an optical disc tilt control device according to a second embodiment of the present invention. The difference from the first embodiment is that when the input of the gradient drive circuit 16 is input to the adder 23, it is input through the frequency processor 34.

Generally, the frequency response characteristic of the tracking error signal 20 to the input of the translation driving device 12 and the frequency response characteristic of the output signal of the inclination detector 14 to the input of the inclination driving device 16 are different. If the addition is directly performed in this characteristic state, the translational motion is later than the tilt motion in the frequency range of 10 to 100 Hz, and the correction in this frequency range may not be completed in time. In order to compensate for this, by adding the signal of this frequency through the frequency processor 34 that amplifies the signal, the control of correcting the tilt of the optical disk by the tilt of the objective lens can be performed more accurately.

Since the frequency processor performs signal processing in a circuit, it may be a holding function, a switching function, a filter, or the like.

[0028]

As described above, by adding the input signal to the tilt driving device to the translation driving device, the tilt is corrected by tilting the objective lens with respect to the tilt of the optical disk.
When the playback position shifts momentarily, tracking control should be
This control can prevent the occurrence of deviation , and the objective lens can be tilted with respect to the tilt of the optical disc with stable control.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an optical disc tilt control device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of the operation of the optical disc tilt control device in the first embodiment.

FIG. 3 is an explanatory diagram of the operation of the optical disc tilt control device according to the first embodiment;

FIG. 4 is a block diagram showing a configuration of an optical disc tilt control device according to a second embodiment of the present invention;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical disk 3 Objective lens 10 Objective lens movable part 12 Translation drive device 13 Tilt drive device 14 Tilt detector 23 Adder

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toru Nakamura 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-62-2232732 (JP, A) JP-A-5-205 6561 (JP, A) JP-A-61-48138 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 7/09 G11B 7/095

Claims (2)

(57) [Claims] 1. An objective lens for reproducing information from an optical disk, an objective lens movable section that holds the objective lens and moves the objective lens, and a relative tilt amount between the optical disk and the objective lens movable section
An inclination detector that detects the position of the objective lens movable section in response to a signal from the inclination detector; a photodetector that detects a reproduction position of the objective lens on the optical disc; A tilt control device for an optical disc, comprising: a translation drive device that drives the objective lens movable portion in a translation direction in accordance with a signal from a disc drive; and a calculator that adds and inputs a signal applied to the tilt drive device to the translation drive device. 2. An objective lens for reproducing information from an optical disk, an objective lens movable section for holding the objective lens and moving the objective lens, and an inclination detector for detecting a relative inclination amount between the optical disk and the objective lens movable section. A tilt drive device that tilts the objective lens movable section in response to a signal from the tilt detector; a photodetector that detects a reproduction position of the objective lens on the optical disc; and a signal in response to a signal from the photodetector. A translation driving device that drives the objective lens movable unit in the translation direction; a frequency processor that performs frequency processing on a signal applied to the tilt driving device; and a computing unit that adds and inputs an output of the frequency processing device to the translation driving device. An optical disc tilt control device comprising: