JPH10283642A - Optical information recording nd reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the requirement for a lens position detecting means, to improve the response in a high frequency region and to reduce the size by conducting the servo control of the carriage position to eliminate the long term deviation of the optical axis of an objective lens from an optical center based on the low frequency components of tracking error signals and the detected outer of an attitude sensor. SOLUTION: A lens holder 1 of an objective lens 2 is elasticity held by a spring 3 whose one end is fixed to an actuator base 5 of a carriage 4. A tracking error detecting circuit 6 extracts tracking error signals from the signals from a recording medium 7 and controls the tracking of the holder 1 through an equalizer 8 and a driving circuit 9. Moreover, the low frequency components are taken out from the output of the equalizer 8 through a low pass filter 14, added with the output of an attitude sensor 15 and drive the carriage 4 through a drive circuit 16. Thus, compensations are made for the long term deviation of the optical axis of the objective lens with respect to the optical center and the deviation caused by gravity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical information recording / reproducing apparatus for recording / reproducing information by irradiating an optical information recording medium having information tracks with a light beam focused by an objective lens.

[0002]

2. Description of the Related Art An optical information recording / reproducing apparatus such as an optical disk apparatus is provided with a tracking drive mechanism for causing a pickup to follow a track of the disk and a seek drive mechanism for allowing the pickup to access the inner and outer circumferences of the disk. Have been. Then, record and
When the reproduction is performed, a tracking servo is applied, and the objective lens is controlled so as to follow the track. At this time, the optical axis of the objective lens is displaced with respect to the optical center, which is the optical axis of the light beam incident from the light emitting unit toward the objective lens. , There are some limitations.

For this reason, the conventional optical information recording / reproducing apparatus is provided with means for detecting the position of the objective lens, and the displacement from the original center position of the objective lens (the position where the optical axis of the objective lens coincides with the optical center). The seek mechanism (access means) is configured to operate so as not to increase. FIG. 7 shows an example of a pickup provided with such a lens position detecting means.

In FIG. 7, a lens holder 101 which is a frame of a pickup holds an objective lens 102, a tracking coil 103 and a focusing coil 104, and is elastically supported by one end of a leaf spring 105.

The other end of the leaf spring 105 is connected to a carriage 106
Are fixed to an actuator base 107 provided at the bottom.

Reference numeral 108 denotes a magnet, which is a yoke 10
9 and is fixed to the carriage 106, and forms a magnetic circuit together with the yoke 110 on the opposite side.

A projection 101a is provided on the lens holder 101, and a part of the projection 101a is disposed between the light projecting section 111a and the light receiving section 111b of the photo sensor 111 fixed to the carriage 106. .

In such a configuration, when the tracking coil 103 is energized based on the tracking error signal obtained by the disk track scanning, the lens holder 101
Is driven in the direction of the arrow in the figure. The displacement of the objective lens 102 from the optical center (optical axis) at this time is obtained as a change in the output of the photosensor 111, and the carriage 106 is moved by a drive mechanism (not shown) so that the displacement falls within a predetermined range. It is driven in the direction of displacement of the objective lens.

In summary, the carriage performs a part of the seek operation and part of the tracking operation in this way.

[0010]

However, in the lens holder 101 provided with the lens position detecting means composed of the photo sensor 111 and the protrusion 101a as described above, the protruding portion 101a causes higher-order sub-resonance. For this reason, the servo gain in the high-frequency region of the tracking servo and the focusing servo must be reduced, which causes a problem in the responsiveness of the tracking servo and the focusing servo particularly in the high-frequency region.

Further, since the photosensor 111 must be mounted on the carriage 106 which is a movable part,
There is also a problem that a load is imposed on a driving mechanism for driving the carriage 106.

Accordingly, an object of the present invention is to provide a photo sensor 1
The carriage control is performed to make the optical axis of the objective lens coincide with the optical center without using the lens displacement detecting means composed of the projection 11 and the projection 101a.

[0013]

According to an optical information recording / reproducing apparatus for recording / reproducing information by irradiating an optical information recording medium having an information track with a light beam condensed by an objective lens, a holder is provided. A tracking drive unit for following an information track and a holder for integrally holding the objective lens; a support unit for elastically supporting the holder so that an optical axis of the objective lens coincides with an optical center; An access unit mounted with the support unit and configured to access and move the holder to a desired track; an attitude detection unit configured to detect an attitude in which gravity acts in a tracking direction; a tracking control unit configured to control the tracking drive unit; An access control means for controlling the access means in accordance with the outputs of the control means and the attitude detection means Characterized in that it comprises and.

In an optical information recording / reproducing apparatus for recording / reproducing information by irradiating a light beam condensed by an objective lens onto an optical information recording medium having an information track, a holder follows the information track. A holder for integrally holding the tracking drive unit and the objective lens, a support unit for elastically supporting the holder so that the optical axis of the objective lens coincides with the optical center of the objective lens, the holder, An access unit mounted with the support unit, for moving the holder to a desired track, a vibration / shock detection unit for detecting vibration and shock of the apparatus main body, a tracking control unit for controlling the tracking drive unit, and the tracking An access control means for controlling the access means in accordance with the output of the control means and the vibration / shock detection means Characterized in that it comprises a means.

Further, the vibration / shock detecting means includes an acceleration detecting means and a low-frequency filter for extracting a low-frequency component of the output of the acceleration detecting means.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] An embodiment according to the present invention will be described below. FIG. 1 is a block diagram showing an entire embodiment of the present invention, and FIG. 2 is a diagram showing a configuration of a pickup portion of the embodiment.

The lens holder 1 holds the objective lens 2 and is elastically supported by one end of a spring 3. The other end of the spring 3 is fixed to an actuator base 5 provided on the carriage 4.

Reference numeral 6 denotes a tracking error detection circuit, which extracts a tracking error signal from a signal obtained from a recording medium 7 such as a disk, and outputs this output to an equalizer 8. The output of the equalizer 8 is input to a tracking coil 10 (FIG. 2) fixed to the lens holder 1 via a drive circuit 9. In FIG. 2, reference numeral 11 denotes a magnet, which is fixed to the carriage 4 via a yoke 12, and forms a magnetic circuit together with the yoke 13 on the opposite side.

The low frequency component of the output of the equalizer 8 is extracted through a low-pass filter (LPF) 14, added to the output of the attitude sensor 15, input to a drive circuit 16, and the driving of the carriage 4 is performed. Converted to a signal.

The attitude sensor 15 is provided on a device fixing portion (not shown) and is arranged to detect the inclination of the device on which gravity acts in the tracking direction.

FIG. 3 is a diagram showing an example of the attitude sensor.
Utilizing the fact that the slider 18 coupled to the weight 17 faces vertically downward, the attitude is detected by the angle between the reference position of the variable resistor 19 and the slider 18. Center of rotation of the slider 18 20, also serves as an output terminal of the divided voltage V _OUT of the power supply voltage V _E.

In such a configuration, for example, when power is not supplied to the tracking coil 10 and no other external force is applied, the optical force of the objective lens 2 is increased by the elastic force of the spring 3 as shown in FIG. Are located in agreement with the optical center of the pickup unit.

FIG. 4 shows a state where the optical axis of the objective lens 2 and the optical center of the pickup unit are shifted. Such a shifted state occurs in the following three cases.

(I) When a certain voltage is applied to the tracking coil 10, the displacement x is
0 is determined by the balance between the force generated by the action of the magnetic circuit and the restoring force of the spring 3.

(Ii) When the apparatus is held in such a position that gravity is applied in the direction of the arrow in the figure, the displacement x is determined by the balance between the gravity applied to the movable part and the restoring force of the spring 3.

(Iii) When the above two terms are superimposed. In the above (i), taking the case where the recording medium is a disk as an example,
When the tracking operation is performed, a sinusoidal waveform as shown in FIG. 5A is obtained as the output of the equalizer 8. In the tracking operation, the tracking of the eccentricity of the disk is mainly dominant, and the tracking operation has a sinusoidal waveform including a large number of the same frequency components as the frequency corresponding to the rotation cycle of the disk as shown by a solid line in the figure.

As shown in FIG. 5B, a DC component indicated by a broken line in FIG. 5A is extracted from the low-pass filter (LPF) 14. This component corresponds to the displacement x of the displacement between the optical axis of the objective lens 2 and the optical center of the pickup unit. The output from the attitude sensor 15 is at zero level as shown in FIG.
The same signal is input as it is through the adder,
The carriage 4 is driven in a direction to make the displacement x zero. Then, the actuator base 5 fixed to the carriage 4 also moves together with the carriage 4 in the direction in which the displacement amount x becomes zero.
Is returned to the non-displacement shape.

In (ii), when the tracking operation is performed, a waveform as shown in FIG. 5D is obtained as the output of the equalizer 8. Low-pass filter (LPF) 14
5 (e) is at zero level, and the output from the attitude sensor 15 is obtained by the tracking direction component of gravity as shown in FIG. 5 (f), which corresponds to the displacement x. In other words, the attitude sensor 15 is adjusted so that a signal of the same level as the output of the tracking error detection circuit corresponding to the tracking error generated by the gravity acting in the tracking direction is generated.
The same signal as the signal in FIG. 5F is directly input to the drive circuit 16 through the adder, and the carriage 4 is driven in a direction to make the displacement amount x zero. This is a feedforward control for preventing a tracking shift due to gravity.

It is clear that the above (iii) is a combination of these.

As described above, even if the cause of displacement of the optical axis of the objective lens 2 with respect to the optical center of the pickup unit is a long-term tracking error due to a track position accuracy error or the like, it is a gravity direction component. However, it is possible to drive the carriage 4 in a direction to correct it.

[Second Embodiment] FIG. 6 is a block diagram showing a second embodiment. This embodiment is the same as the first embodiment except that a vibration impact detection unit is provided instead of the posture detection unit. Therefore, description of common parts is omitted, and only different points will be described.

The acceleration sensor 2 is used as vibration / impact detection means.
1 and a low-pass filter (LPF) 22. The output of the acceleration sensor 21 in which only the low-frequency component is extracted by the low-pass filter (LPF) 22 is supplied to the drive 16 after being added to the tracking error signal that has passed through the equalizer 8 and the low-pass filter (LPF) 14. . Examples of the acceleration sensor include a capacitance type and a sensor using a piezo element. The acceleration sensor 21
Is input to the main CPU 23 which is a control unit of the entire apparatus. The main CPU monitors the input from the acceleration sensor 21 and outputs a laser output in order to prevent the pickup from leaving the track and recording a signal in a wrong place when vibration or impact is applied to the apparatus. Controls disconnection.

In such a configuration, the vibration can be detected by detecting the vibration or shock applied to the apparatus, and the tracking can be corrected by feedforward so as to cancel the tracking deviation caused by the vibration or shock. Therefore, abnormal situations such as recording on the wrong track and reproducing from the wrong track in the recording or reproducing operation can be prevented from the viewpoint of tracking.

Although the two embodiments have been described above, an embodiment in which both embodiments are combined, that is, which includes an attitude detecting means and a vibration / shock detecting means and which passes through the equalizer 8 and the low-pass filter (LPF) 14 There is also a form in which both outputs are added to the tracking error signal obtained and supplied to the drive circuit 16.

In each of the embodiments, the tracking error detection circuit 6, the equalizer 8, the drive circuit 9, the tracking coil 10, the magnet 11, the yokes 12 and 13, the tracking actuator, the spring 3, A first control, a tracking error detection circuit 6, which is a tracking servo composed of:
A second control which is a tracking servo composed of an equalizer 8, a low-pass filter (LPF), a drive circuit 16, a carriage 4, an actuator base 5, and a spring 3, and a posture detecting means or a vibration shock detecting means , A drive circuit 16, a carriage 4, an actuator base 5, and a third control that is a feedforward control including the spring 3. That is, in both embodiments, triple control is configured.

[0036]

According to the present invention, the servo of the carriage position for eliminating the long-term deviation of the optical axis of the objective lens from the optical center is performed based on the low-frequency component of the tracking error signal. Need not be performed based on the lens position detecting means including the photosensor and the projection. Therefore, it is not necessary to provide a projection for generating a higher-order sub-resonance during the tracking operation of the optical pickup, so that the servo gains of the tracking servo by the tracking coil and the focusing servo by the focusing coil can be increased. It is possible to provide an optical information recording / reproducing apparatus having a good and compact carriage driving mechanism.

When a force in the tracking direction acts on the pickup due to disturbance such as gravity or vibration or impact, feedforward control is performed so as to cancel the force, so that tracking becomes strong against these disturbances. .

Further, since there is no need to provide a dedicated lens position detecting means comprising the photosensor and the projection for detecting the deviation of the optical axis of the objective lens from the optical center, the cost is reduced.

Further, the acceleration sensor used for controlling the laser output by monitoring the vibration / shock applied to the apparatus can be used also as the vibration / shock means for the present invention, so that the cost increase is small.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a pickup part according to the present invention.

FIG. 3 is a diagram illustrating an example of a posture sensor used in the present invention.

FIG. 4 is a diagram showing a state where the objective lens according to the present invention has a displacement.

FIG. 5 is a signal waveform diagram according to the present invention.

FIG. 6 is a block diagram showing an overall configuration of a second embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of a pickup portion according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lens holder 2 Objective lens 3 Spring 4 Carriage 5 Actuator base 6 Tracking error detection circuit 7 Recording medium 8 Equalizer 9 Drive circuit 10 Tracking coil 11 Magnet 12, 13 Yoke 14 Low-pass filter (LPF) 15 Attitude sensor 16 Driver circuit 17 Weight 18 Slider 19 Variable resistor 20 Center of rotation 21 Acceleration sensor 22 Low-pass filter 23 Main CPU

Claims (3)

[Claims] 1. An optical information recording / reproducing apparatus for recording / reproducing information by irradiating an optical information recording medium having an information track with a light beam focused by an objective lens, wherein the objective lens is provided on the information track. A holder for integrally holding the tracking lens and the objective lens; a holder for elastically supporting the holder so that an optical axis of the objective lens coincides with an optical center; and the holder and the holder. Mounting means for accessing and moving the holder to a desired track; posture detecting means for detecting a posture in which gravity acts in a tracking direction; tracking control means for controlling the tracking driving means; and an output of the posture detecting means. And an access control means for controlling the access means according to Information recording and reproducing apparatus. 2. An optical information recording / reproducing apparatus for recording / reproducing information by irradiating an optical information recording medium having an information track with a light beam condensed by an objective lens, comprising: A holder for integrally holding the tracking lens and the objective lens; a holder for elastically supporting the holder so that an optical axis of the objective lens coincides with an optical center; and the holder and the holder. Mounting means for accessing and moving the holder to a desired track; vibration and shock detection means for detecting vibration and shock of the apparatus main body; tracking control means for controlling the tracking drive means; Access control means for controlling the access means according to the output of the vibration / shock detection means. An optical information recording / reproducing device characterized in that 3. The optical information recording / reproducing apparatus according to claim 2, wherein the vibration / shock detecting means includes an acceleration detecting means, and a low-frequency filter for extracting a low-frequency component of an output of the acceleration detecting means. An optical information recording / reproducing apparatus characterized by the above-mentioned.