JP3731451B2 - Collision prevention device for optical pickup - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a collision prevention device for an optical pickup unit, and more particularly to a collision prevention device for an optical pickup unit that can perform information recording and / or information reproduction with respect to an optical disc and has an actuator unit that can be driven in a magnetic forming unit.
[0002]
[Prior art]
An optical pickup for recording and / or reproducing information on a wide variety of optical disks such as MD, CD, CD-R, CD-RW, DVD, DVD-RAM, etc. is used in a CD reproducing device as an example. Then, the configuration is as shown in FIG.
[0003]
An optical pickup unit 1 for reproducing a disk D on which an audio signal is digitally recorded has a magnet unit 6 fixed to the base, and an actuator unit 2 disposed inside the magnetic forming unit. The actuator unit 2 is held via a flexible support unit 4 that is cantilevered by a support unit 5, a lens 3 is attached to the center, and a drive coil 2 a is provided around it.
[0004]
When a servo signal for driving in the focus direction is supplied to the drive coil 2a, the actuator unit 2 is driven in the focus direction to cause the disk D to reproduce an audio signal in a just-focused state. be able to.
[0005]
In this case, in a normal state where a servo signal is supplied to the drive coil 2a, sufficient servo control is performed so that malfunction does not occur due to this disturbance component even if vibration is applied to the optical pickup unit 1, and thus stable. Thus, optical signal reading can be performed.
[0006]
Further, in a state other than the normal state, since no signal is supplied to the drive coil 2a, the entire actuator portion 2 is in a predetermined equilibrium position by the cooperative action with the flexible support portion 4 by its own weight. And is flexibly supported in a state sufficiently separated from the surface of the disk D.
[0007]
In this state, there is no particular problem if the optical pickup unit 1 is in an environment where there is no large vibration. However, when the optical pickup unit 1 is an in-vehicle device, the actuator unit 2 is driven by vibration during traveling, etc. It is moved (vibrated) greatly against the flexible force caused by. In order to prevent this, the stopper portion 7 is provided, and even if the actuator portion 2 moves upward, the upper end of the stopper portion abuts against the stopper surface 7a, and the lens 3 may collide with the disk surface of the disk D. It is prevented. In addition, when the actuator unit 2 has been greatly moved (vibrated) downward due to a disturbance, the lower end surface of the actuator unit 2 is brought into contact with the bottom wall surface 1a.
[0008]
On the other hand, as disclosed in JP-A-59-127240, when the actuator unit is in a state other than the normal state, the position of the actuator unit is mechanically and forcibly retracted to the holding position. There are also examples.
[0009]
Further, as disclosed in JP-A-59-186147, when the actuator unit is in a state other than the normal state, the actuator unit is forcibly held in the retracted position with respect to the drive coil of the actuator unit. There is also an example in which such a servo signal is supplied.
[0010]
[Problems to be solved by the invention]
In the case of a collision prevention device provided with mechanical stopper means, not only is the structure complicated, but there is a risk that it will hinder the thinning and weight reduction of the overall shape of the actuator part, which is particularly strongly demanded in recent years. There is.
[0011]
In the case of an anti-collision device configured to mechanically and forcibly retract the position of the actuator unit to the holding position when the actuator unit is in a state other than the normal state, the actuator unit is moved to a predetermined retracted position. In order to press, it is necessary to lengthen a large amount of drive current to the drive coil, and there is a risk that the temperature of the drive coil rises, the member for supporting the actuator section is deformed, or the product life is shortened.
[0012]
In addition, when the actuator unit is in a state other than the normal state, a collision prevention device is provided so that the servo is always applied to the drive coil of the actuator unit so that the actuator unit is forcibly held in the neutral position. In the case of the configuration, particularly an acceleration detecting means for detecting a disturbance component is required, so that there is a possibility that a significant cost increase is caused.
[0013]
Therefore, the object of the present invention is to reduce the overall shape and weight of the actuator part, and to reduce the product life due to the temperature rise of the drive coil and deformation of the member for supporting the actuator part, An object of the present invention is to provide an optical pickup collision prevention apparatus that does not require a complicated configuration such as acceleration detection means.
[0014]
[Means for Solving the Problems]
In order to solve the above-described problems, the optical pickup unit collision preventing apparatus according to the present invention employs a characteristic configuration as described below.
[0015]
(1) In a collision prevention apparatus for an optical pickup unit that can perform information recording and / or information reproduction with respect to an optical disc and has an actuator unit that can be driven in a magnetic forming unit.
In order to intermittently control the actuator unit at a frequency sufficiently higher than the support resonance frequency of the movable mechanism of the actuator unit, except when the actuator unit is normally recording and / or reproducing information. Detecting means for detecting a back electromotive signal generated in the actuator unit when the actuator unit is driven by disturbance due to external vibration or the like during the stop,
A / D conversion means for converting the back electromotive signal detected by the detection means into a digital signal;
Interpolation means for interpolating the digital signal converted by the A / D conversion means;
Collision of an optical pickup unit comprising a control unit that generates and supplies a control signal to the actuator unit that cancels a disturbance component detected by the detection unit based on the signal interpolated by the interpolation unit Prevention device.
[0016]
(2) The collision preventing device for the optical pickup unit, wherein the detection means of (1) is configured to detect a counter electromotive current generated in a drive coil provided in the actuator unit.
[0017]
(3) The detection means of (1) is an optical pickup unit configured to detect a counter electromotive current generated in a drive coil of an actuator unit that is movably disposed in a magnetic forming unit formed by a magnet unit. Anti-collision device.
[0018]
(4) The detection means of (1) is configured to detect the back electromotive current obtained from the actuator unit based on data sampled at a predetermined period, and the control means of (1) is a detection means. An anti-collision device for an optical pickup unit configured to generate the control signal based on the obtained data.
[0019]
(5) The collision preventing device for an optical pickup unit, wherein the control means of (1) is configured to generate the control signal based on analog data obtained from the actuator unit.
[0020]
(6) A collision prevention device for an optical pickup unit having the detection means of any one of (1) to (5) and the control means of any of (1) to (5) is configured as an in-vehicle device. Anti-collision device for this optical pickup.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a collision preventing device for an optical pickup unit according to an embodiment of the present invention will be described with reference to FIGS. This embodiment is an example in which the present invention is applied to an actuator unit used in a CD playback device. The optical pickup unit 8 disposed opposite to the disk surface of the disk D has a magnet unit 11 fixed to its base, An actuator unit 9 is disposed inside the magnetic forming unit. The actuator unit 9 is held via a flexible support unit 13 that is cantilevered by a support unit 12, a lens 10 is attached to the center, and a drive coil 9 a is provided around it.
[0022]
During normal optical reproduction, the focus error signal generated by the optical pickup unit 8 enters the analog processing unit 15, and the signal from which high frequency noise has been removed is A / D converted by the A / D conversion unit 16. And input to the F servo calculation unit 17. The control signal generated by the F servo calculation unit 17 is D / A converted by the D / A conversion unit 20, amplified by the drive amplifier unit, applied to the coil of the actuator unit 9, and the distance between the lens and the disk is increased. In other words, the focus error signal is kept substantially zero so as to be constant.
[0023]
The circuit connected to the optical pickup unit 8 is configured by adding new “detection means” and “control means” to the conventional focus servo control circuit, and this “detection means” is an actuator. "Control means for detecting a back electromotive signal generated in the actuator unit 9 when the actuator unit 9 is driven by disturbance due to external vibration or the like except when the unit 9 is normally reproducing information" The control signal is supplied to the actuator unit 9 so as to cancel the disturbance component detected by the detecting means.
[0024]
The clock generation unit 14 generates a reference clock for operation in the control circuit unit a, and the analog processing unit 15 removes a noise component of the back electromotive current from the drive coil 9a. The analog processing unit 15 The obtained back electromotive force signal is A / D converted by the A / D converter 16. As for the intermittent signal obtained by the A / D conversion unit 16, a control current waveform is generated by the interpolation processing unit 18 and the waveform calculation unit 19, and this control current waveform is D / A converted by the D / A conversion unit 20. The
[0025]
The timing for intermittently stopping the control current and detecting the back electromotive current is executed by a clock signal from the clock generation unit 14.
[0026]
Such a control unit functions when the apparatus power is supplied and the optical pickup unit 8 is in a non-operating state. This is because, in the case of an in-vehicle system, the vehicle is running or the engine key is on, and the optical pickup This corresponds to a state where the optical reproduction by the unit 8 is not performed.
[0027]
The output of the D / A conversion unit 20 is passed through the drive amplifier unit 21 formed of a series circuit of the amplifier unit 22 and the current detection unit 23, and the output output from the current detection unit 23 is supplied to the drive coil 9a of the optical pickup unit 8 as a control current. Supplied. Accordingly, in a state where a normal servo control signal is not supplied to the drive coil 9a, a back electromotive current is generated in the drive coil 9a due to free vibration of the actuator unit 9.
[0028]
This back electromotive current is detected by the analog processing unit 15 and the A / D conversion unit 16 constituting the control circuit unit a, and the output signal of the D / A conversion unit 20 is sent to the drive coil 9a via the drive amplifier unit 21. The current value approaches zero by the output control current.
[0029]
If such an operation is continuously performed, the back electromotive force and the control current are in a balanced state. Therefore, the current value flowing through the drive coil 9a becomes substantially zero, but the vibration of the actuator unit 9 (lens 10) is free vibration. It can only be suppressed to about half of that. That is, as shown in FIG. 2, the counter electromotive current S1 during the operation of the lens 10 during free vibration is the combined current U1 obtained as a result of the counter electromotive current and the control current overlapping like the control current T1. The gain is doubled. Therefore, the signal corresponding to the actual vibration amount of the lens 10 has a waveform that is substantially equal to the control current T1, such as the back electromotive force S2.
[0030]
Therefore, the control is intermittently stopped at a frequency sufficiently higher than the support resonance frequency of the movable mechanism of the actuator unit 9, and the counter electromotive current value during the stop is detected and curve interpolation is performed in the vicinity of the support resonance frequency. Thus, sampling control for generating a new control current is performed. Then, since the amplitude due to the free vibration of the actuator portion 9 becomes the maximum near the support resonance frequency, it hardly responds to the signal intermittent portion of the control current, and the back electromotive force is substantially zero by eliminating the influence of the disturbance factor. In other words, the vibration amplitude of the actuator unit 9 can be suppressed to substantially zero. These signal forms are shown as a control current T2, a combined current U2, and a counter electromotive current S3 in FIG.
[0031]
The form described so far is the case where the optical disc is a CD, but it can be applied to all of a wide variety of discs such as MD, CD-R, CD-RW, DVD, DVD-RAM, etc., and an optical pickup. Of course, the unit may be any of read-only, record-only, and record-playback.
[0032]
【The invention's effect】
As is clear from the above description, the optical pickup collision preventing device according to the present invention is driven by disturbance due to external vibrations, etc., except when the actuator unit is normally recording and / or reproducing information. And detecting means for detecting a back electromotive force signal generated when the control signal is generated, and control means for supplying a control signal to the actuator unit so as to cancel disturbance components detected by the detecting means. Therefore, there are the following effects.
[0033]
Each of the new “detection means” and “control means” can be configured integrally with an integrated circuit that performs conventional focus servo control, and the actuator section does not require any additional structure. It is not complicated, and it is possible to reduce the overall shape and weight of the actuator part, which has been particularly strongly demanded in recent years, and it is not necessary to pass a large amount of drive current to the drive coil, making it a member for supporting the actuator part. There is no deformation or shortening of the product life, and no particular acceleration detection means for detecting a disturbance component is required, resulting in an increase in cost.
[0034]
Accordingly, the overall shape of the actuator part can be reduced in thickness and weight, the temperature of the drive coil is increased, and the member for supporting the actuator part is deformed to shorten the product life, and the acceleration detecting means is complicated. It is possible to provide a collision preventing device for an optical pickup unit that does not require a special configuration.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a collision prevention device for an optical pickup unit according to an embodiment of the present invention.
FIG. 2 is a waveform diagram for explaining the operation of continuous control of the collision prevention device for the optical pickup section shown in FIG. 1;
3 is a waveform diagram for explaining an intermittent control operation of the collision prevention device for the optical pickup unit shown in FIG. 1; FIG.
FIG. 4 is a schematic configuration diagram illustrating an example of an optical pickup unit of a conventional collision prevention device for an optical pickup unit.
[Explanation of symbols]
8 Optical pickup section 9 Actuator section 9a Drive coil 10 Lens 10
DESCRIPTION OF SYMBOLS 11 Magnet part 12 Support part 13 Flexible support part 14 Clock generation part 15 Analog processing part 16 A / D conversion part 17 F Servo calculation part 18 Interpolation process part 19 Waveform calculation part 20 D / A conversion part 21 Drive amplifier part 22 Amplifier Part 23 Current detection part

Claims (6)

In a collision preventing device for an optical pickup unit that can perform information recording and / or information reproduction with respect to an optical disc and has an actuator unit that can be driven in a magnetic forming unit.
In order to intermittently control the actuator unit at a frequency sufficiently higher than the support resonance frequency of the movable mechanism of the actuator unit, except when the actuator unit is normally recording and / or reproducing information. Detecting means for detecting a back electromotive signal generated in the actuator unit when the actuator unit is driven by disturbance due to external vibration or the like during the stop,
A / D conversion means for converting the back electromotive signal detected by the detection means into a digital signal;
Interpolation means for interpolating the digital signal converted by the A / D conversion means;
And a control unit that generates and supplies a control signal to the actuator unit that cancels a disturbance component detected by the detection unit based on the signal interpolated by the interpolation unit. Collision prevention device for optical pickup unit.   2. The collision preventing device for an optical pickup unit according to claim 1, wherein the detection unit is configured to detect a counter electromotive current generated in a drive coil provided in the actuator unit.   The said detection means is comprised so that the back electromotive force produced in the drive coil of the actuator part arrange | positioned movably in the magnetism formation part formed of the magnet part may be detected. Collision prevention device for optical pickup unit. The detection means is configured to detect the back electromotive force obtained from the actuator unit based on data sampled at a predetermined period,
2. The collision prevention apparatus for an optical pickup unit according to claim 1, wherein the control unit is configured to generate the control signal based on data obtained by the detection unit.   2. The collision prevention device for an optical pickup unit according to claim 1, wherein the control unit is configured to generate the control signal based on analog data obtained from the actuator unit.   6. The collision prevention device for an optical pickup unit according to claim 1, wherein the collision prevention device for the optical pickup unit having the detection unit and the control unit is configured as an in-vehicle device.

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