JPH0628113B2 - Information recording / reproducing device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an information recording / reproducing apparatus having a rotating disk-shaped recording medium such as an optical disk.

[Prior Art] FIG. 4 is a block diagram showing a configuration of a compact disc player which is a kind of conventional information recording / reproducing apparatus. In FIG. 4, (1) shows a disc (generally, information recording in the form of a rotating disc). Medium), (1a) is its rotation mechanism, (2)
Is a pickup, (3) is a pickup actuator, (4) is a pickup holder, (5) is a holding part,
(6) is a vibration insulator, (7) is a focus servo circuit, and (8) is a track servo circuit.

The actuator (3) finely adjusts the position of the lens held by the actuator (3) with respect to the disc (1), and the pickup holder (4) includes a pickup (2), an actuator (3), and a rotation mechanism. (1a) is fixed, and the pickup holder (4) is held by the holding portion (5) via the vibration insulator (6) to prevent transmission of vibration.

A pickup for a compact disc player is composed of an objective lens, a light source and a photoelectric conversion device.
The focal point of the objective lens must be in a correct relational position with respect to the disc (1) in a direction (probably the z direction) perpendicular to the plane of the disc (1), and also in the radial direction of the disc (1). It must be in the correct relative position with respect to the disc (1) in the r direction). With respect to relative vibration between the disc (1) and the pickup holder (4), the z-direction and r-direction positions are automatically controlled by the servo circuits (7) and (8) and the actuator (3). is doing. Therefore, the actuator (3) is divided into a focus actuator and a track actuator.

FIG. 5 is a block diagram showing a configuration example of the focus servo circuit (7) and the track servo circuit (8) in FIG. 4, and the same reference numerals as those in FIG. 4 indicate the same or corresponding parts,
(3a) is a focus actuator, (3b) is a track actuator, (9) and (9a) are detectors for detecting an error between the surface vibration of the disc (1) and the displacement of the focus actuator (3a), (13a). ), (13)
Is the eccentricity of the disk (1) and the track actuator (3
It is a detector that detects an error from the displacement of b).

(10), (14) are preamplifiers, (11),
(15) is a compensation circuit, (12) and (16) are drivers, and compensation circuits (11) and (15)
Is a circuit that adds a differential characteristic and / or an integral characteristic in order to improve the characteristic of feedback control.
9) and (20) indicate the displacement amounts of the actuator (3) in the z direction and the r direction. Detector (9), (1
The loop gain of this feedback control is from the input point of 3) to the output point of the actuator (3). It is well known that the larger the loop gain, the smaller the servo tracking error.

[Problems to be Solved by the Invention] Since the conventional device is configured as described above, the relative position between the pickup holder (4) and the disc (1) causes the position in the z direction or (and ) Even if an error occurs in the position in the r direction, the servo circuit performs control so that the error is always zero. However, the position error due to vibration contains a relatively high frequency component, and the loop gain of the servo circuit becomes small for this high frequency component, and the position error cannot be made sufficiently small. It is possible to improve the loop gain at a high frequency, but if this causes a drop in the information recorded on the disc (1), the problem of track skipping occurs and the disc (1)
Even if the recording is complete, there was a problem that the drive current of the servo system had to be increased in order to improve the loop gain. Therefore, in the conventional device, the loop gain is kept relatively low and the vibration insulator (6) is used so that the vibration is not transmitted to the pickup (2), but it is difficult to sufficiently insulate the vibration. It was

The present invention has been made in order to solve the above-mentioned problems in the conventional one, and even when the disc (1) has a scratch, it does not cause a track jump and satisfactorily follows a position error due to vibration. The purpose is to obtain an information recording / reproducing apparatus that can be used.

[Means for Solving the Problem] In the present invention, the loop gain is improved only when relative vibration occurs between the disc (1) and the pickup (2).

[Operation] Since the loop gain is kept relatively low while vibration is not occurring, the drive current of the servo system does not increase,
Track jumping does not occur, and vibration can be tracked accurately by a high loop gain.

Embodiments Embodiments of the present invention will be described below with reference to the drawings. First
The figure is a block diagram showing an embodiment of the present invention. In the figure, the same reference numerals as those in FIG.
1) and (22) constitute an angle detector, and (21) is LE
D and (22) are light receiving elements. Further, (24) indicates an angle detection circuit, and (25) and (26) indicate control signals.

When some shock is applied to the housing of the player, the holding portion (5) connected to the housing first vibrates. Since the vibration insulator (6) is interposed between the holding part (5) and the pickup holder (4), the vibration of the holding part (5) and the vibration of the pickup holder (4) are different from each other. The pickup holder (4) has its rotation mechanism (1
The relative angular change between the plane of the disk (1) to which a) is fixed and the LED (21) and the light receiving element (22) fixed in one surface of the holding portion (5). The angle detector (21), () changes so that this angle change is a change in the amount of light emitted from the LED (21), reflected by the surface of the disk (1), and input to the light receiving element (22). Two
2) is arranged, the amount of light incident on the light receiving element (22) is converted into an electric signal, and the angle detection circuit (2
4) is input.

FIG. 2 is a block diagram showing the configuration of the angle detection circuit (24), focus servo circuit (7) and track servo circuit (8) of FIG. 1, and the same reference numerals as those in FIGS. 1 and 5 are the same. Or (27) is a filter,
(28) is a comparator, and (29) is a logic circuit.

FIG. 3 is a waveform diagram showing the output waveform of each part of the angle detection circuit (24) shown in FIG. 2, showing the output of the filter (27), the output of the comparator (28), and the output of the logic circuit (29). .

The filter (27) passes only the frequency component that needs to be tracked by the servo mechanism, and the comparator (28) improves the servo loop gain to determine the magnitude of vibration that needs to be addressed. When the amplitude of the vibration waveform of the output of the filter (27) exceeds the threshold value in the positive direction or the negative direction, the comparator (28) outputs the output as shown in FIG. The logic circuit (29) outputs a signal of logic "1" for a predetermined time T from the time when this output first rises. This becomes the control signals (25) and (26).

A gain switching circuit (not shown) is included in the compensation circuits (11) and (15) of FIG.
Only while the logic of (26) is "1", switching is performed to increase the loop gain, and control is performed so as to reduce the focus error and the track error even with respect to vibration. Also,
When there is no vibration of a predetermined amplitude or more, the loop gain is kept low and operates stably, the operating current of the actuator is kept low, enabling low power consumption and low noise, and Can improve the reproduction ability of the.

In the above embodiment, the LED (2
1), the optical sensor composed of the light receiving element (22) is used, but any other angle detector may be used.

Further, even if only one of the focus servo circuit and the track servo circuit is controlled, a considerable effect can be obtained.

Further, a laser vision (LV) player or the like may have a built-in tilt servo mechanism for detecting the information surface of the disc and the angle of the pickup and adjusting the tilt of the pickup. In this case, the angle between the pickup and the disc is adjusted. Since the sensor for detecting is provided, this sensor can also be used as an angle detector.

As described above, according to the present invention, the angle detector for detecting the vibration applied to the information recording / reproducing apparatus is provided, and only when the vibration of a predetermined value or more is applied, the loop gain of the servo system is increased. As a result, it is possible to obtain an information recording / reproducing apparatus which has a high vibration resistance and an excellent scratch disk reproducing ability.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is an angle detection circuit and a focus servo circuit shown in FIG.
FIG. 3 is a block diagram showing the configuration of the track servo circuit, FIG. 3 is a waveform diagram showing the output waveform of each part of the angle detection circuit shown in FIG. 2, and FIG. 4 is a block diagram showing the configuration of a conventional device.
The figure is a block diagram showing the configuration of the focus servo circuit and the track servo circuit shown in FIG. (1) is a disk, (1a) is a rotation mechanism, (2) is a pickup, (3) is an actuator, (4) is a pickup holder, (5) is a holding part, (6) is a vibration insulator, and (7) is Focus servo circuit, (8) track servo circuit, (21), (22) angle detector, (2
4) is an angle detection circuit, (25) and (26) are control signals,
(27) is a filter, (28) is a comparator, (2
9) is a logic circuit. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A rotating disk-shaped information recording medium on which information is recorded, a pickup for reading the information recorded on the information recording medium, and a pickup actuator for controlling the position of the pickup with respect to the information recording medium. A pickup holder to which the pickup and the rotation mechanism of the recording medium are fixed; a holding portion that holds the pickup holder via a vibration insulator that prevents transmission of vibration; A focus servo circuit for automatically controlling the position of the information recording medium in a direction perpendicular to the disc surface; and a track servo circuit for automatically controlling the radial position of the disc surface of the information recording medium of the pickup via the pickup actuator. In an information recording / reproducing apparatus having An angle detector for detecting a relative angle between a predetermined portion of the disc surface of the information recording medium and a plane of the predetermined portion of the holding portion, a predetermined frequency band among frequency components included in the output of the angle detector A filter that allows the components inside to pass through, a comparator that detects when the output of this filter exceeds a predetermined amplitude, a logic circuit that generates a control signal of a predetermined time width from the detection time of this comparator, and the presence of the control signal An information recording / reproducing apparatus comprising: means for controlling a loop gain of the focus servo circuit and / or the track servo circuit to increase during a period.