JPH03266223A - Optical disk device - Google Patents

Abstract

PURPOSE:To realize high-speed and highly precise information access by adding a moving speed signal showing the speed of the condenser lens to a speed pulse, generating the relative speed signal of condenser lens to an optical disk, and executing the low pass filtering of this relative speed signal. CONSTITUTION:When the condenser lens 15 moves, dislocation is caused between an optical head 100 and the condenser lens 15 because of the reaction force of supporting bodies 19a, 19b, and the condenser lens 15 is driven excessively by the portion of this dislocation. The moving speed signal showing the actual sped of the condenser lens 15 is obtained by subtracting this dislocation quantity from the driving quantity of the condenser lens 15 by a driving source, and after summing up the obtained moving speed signal and the sped pulse outputted at every movement of definite distance of the condenser lens 15, the low pass fitering is executed, and a speed signal is obtained. Accordingly, as for the obtained speed signal, the dislocation component of the condenser lens 15 to the optical head 100 is removed, and simultaneously, a high frequency component is compensated, and it comes to show the correct speed of the condenser lens 15. Thus, the stabler and more highly precise information access can be executed more surely.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides a method in which a focusing lens that forms a light spot by focusing light from a light source is movably supported by a support having spring characteristics; The present invention relates to an optical disk device including an optical head having a drive source for moving the optical head.

[Prior Art] In a file device such as an optical disk device, a large number of concentric information tracks are formed on a disc-shaped record carrier, and information is accessed by moving a head between the information tracks. There is.

In this case, speed control (changing the moving speed of the head according to the positional error up to the target) is generally performed for movement between relatively distant information tracks, but for this purpose, it is necessary to It is necessary to detect the velocity relative to the carrier.

In conventional optical disk devices, in the case of an optical disk device equipped with an optical head in which a focusing lens that focuses light from a light source to form a light spot can move independently, a track emitted when a light spot crosses an information track. A method has been considered in which a speed signal is obtained by converting a transverse pulse (which is made into a pulse by detecting the zero crossing of the track roller) to F/■ (frequency-voltage). However, simply F/V conversion of the track-crossing pulse does not provide enough detection band for the speed signal, so the speed signal obtained by F/V-converting the track-crossing pulse is used as a drive source such as a motor that drives a focusing lens. There is a method that corrects high frequency components by adding the supplied current signals (for example, Japanese Patent Laid-Open No. 7114/1983).

[Problem to be solved by the invention]

In the above-described method of adding the F/V-converted signal of the track crossing pulse in the conventional optical disk device and the current signal for driving the focusing lens, if the current signal contains other error factors, an error may occur in the speed signal. The disadvantage was that it appeared.

In other words, if the focusing lens is supported within the head frame by a support material such as a spring, the current to counteract the reaction force of the support material will also be supplied to a drive source such as a motor (lens actuator). , if the current signal containing this component and the F/V signal are added, an error will occur in the speed signal. Also, unless the focusing lens is supported by a support material such as a spring, this current deviation will not occur, but in general, the focusing lens is equipped with a support material with spring properties such as a spring or rubber material within the head frame. However, if an attempt is made to control the speed of the movement of the lens, such deviations cannot be ignored.

An object of the present invention is to provide an optical disc device that enables high-speed and highly accurate information access.

[Means for Solving the Problems] An optical disc device of the present invention includes: a lens position detector that detects a positional shift of a focusing lens with respect to a support portion of a support; a pulse generation circuit that outputs a speed pulse; a drive amount detector that detects a current value for a drive source to drive the focusing lens; and a drive amount detected by the drive amount detector that is detected by the lens position detector. a subtraction circuit that generates a moving speed signal indicating the speed of the focusing lens by subtracting the positional deviation, and a relative speed signal of the focusing lens with respect to the optical disk by adding the moving speed signal generated by the subtracting circuit to the speed pulse. and a low-pass filter that performs low-pass filtering of the generated relative velocity signal.

[Function] When the focusing lens moves, a positional shift occurs between the optical head and the focusing lens due to the reaction force of the support, and the focusing lens is driven by an amount corresponding to the positional shift. Subtracting this positional deviation amount from the actual driving amount by the driving source of the focusing lens to obtain a moving speed signal indicating the actual speed of the focusing lens,
After adding the obtained moving speed signal and the speed pulse output every time the focusing lens moves a certain distance, low-pass filtering is performed to obtain the speed signal. The misalignment component is removed and the high frequency component is compensated to provide accurate focusing lens velocity.

[Example] Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the optical disc device of the present invention, and FIG. 2 is a diagram showing signal waveforms of important parts in FIG.

In this embodiment, an optical head 100 and a speed signal generator 200
, an optical head drive section 300 , a laser drive circuit 30 , a differential amplifier 25 , and a power amplifier 26 .
The optical head 100 then irradiates light onto the record carrier 10 to access information on the record carrier 10 .

A large number of concentric information tracks are formed on the surface of the record carrier 10, and an optical head 100 is placed at a predetermined location.
A track position signal that is optically detected by light irradiation is recorded.

The optical head 100 includes a semiconductor laser 11 that receives current from a laser drive circuit 30 to oscillate laser light, a lens 12, a beam splitter 13, a mirror 14, and a focusing lens 15. The light is made into parallel light by a lens 12, passes through a beam splitter 13, is bent by a mirror 14, and enters a converging lens 15. This focusing lens 15 focuses the laser beam to form a minute optical spot on the recording carrier 10, and is supported by the frame of the optical head 100 by supporting members 19a and 19b having spring characteristics, and is also connected to the lens actuator. 18, the optical head 1
It can be moved independently from 00. therefore,
By moving only the focusing lens 15, the optical spot can be moved minutely with respect to the information track of the record carrier 10 without always accurately moving the optical head 100.

When accessing information by irradiating this light spot, the information is recorded by changing the irradiation power of the light spot onto the record carrier 10, and the reflected light from the record carrier l○ changes due to the irradiation of the light spot. Information is read out by capturing the information. When reading information from the record carrier 10, the light reflected from the record carrier 10 passes through the converging lens 15 again, the optical path is bent by the mirror 14, and the optical path is further bent by the beam splitter 13, and then sent to the track nipper detector. 16. The track error detector 16 is divided into two parts, and outputs a current corresponding to the amount of reflected light incident on each part to the speed signal generator 200.

Further, in this embodiment, the lens position detector 17 or the optical head 1
It is attached to the lens actuator 18 of 00,
Detecting the positional deviation of the focusing lens 15 with respect to the frame of the optical head 100 that serves as the support portion of the supporting members 19a and 19b,
The speed signal generator 200 generates a current corresponding to the positional deviation.
Output to.

Lens actuator 1 with a focusing lens 15 attached
8 operates in response to drive current from the power amplifier 26. The power amplifier 26 receives an output signal output from the differential amplifier 25 and indicates the difference between the speed signal 101 and the reference speed signal 102, and outputs a drive current to the lens actuator 18 of the optical head 100. This reference speed signal】0
2 is a signal corresponding to a positional error up to the target position, which is supplied from a control signal generator (not shown) when the optical spot moves between the information tracks.

The speed signal generator 200 includes a differential amplifier 20, a buffer amplifier 21, a speed pulse generator 22, and a low-pass filter 23.
, a subtraction circuit 24 , and a current detection resistor 31 .

The differential amplifier 20 determines the difference between two output currents from the track error detector 16 of the optical head 100 and outputs the difference as a track error signal 110 to the speed pulse generation circuit 22. This track error signal 110 indicates the relative position of the optical spot emitted by the optical head 1o○ with respect to the information track on the record carrier 10. The speed pulse generation circuit 22 receives the track niller signal 110 and generates a speed pulse 1 having a constant amplitude and time width for each zero cross.
Outputs 13. The buffer amplifier 21 is connected to the optical head 10
A current signal corresponding to the positional deviation of the focusing lens 15 output from the lens position detector 17 installed in the lens position sensor 17 is received, the signal is amplified, and the signal is amplified as a lens position signal 111 by the subtraction circuit 24 and the optical head drive unit 300. Output to. The current detection resistor 31 is attached to the output end of the power amplifier 26 and detects the current supplied to the lens actuator 18, that is, the current detected by the lens actuator 18.
The drive amount is detected and output as a drive current signal 112 to the subtraction circuit 24. When determining the speed of the focusing lens 15 driven by the lens actuator 18, if the focusing lens 15 is completely free, the current supplied from the power amplifier 26 to the lens actuator 18 and the acceleration of the focusing lens 15 are proportional. By integrating the driving current signal 112 detected by the current detection resistor 31, the speed of the focusing lens 15 can be determined.
Since the optical head 10 is supported on the frame of the optical head 100 by
A relative positional shift of the focusing lens 15 occurs with respect to the zero frame, and an extra current is supplied to the lens actuator 18 by the amount of the positional shift. Therefore, by subtracting the extra current from the drive current signal 112, the accurate speed of the focusing lens 15 can be determined, and the subtraction is performed by the subtraction circuit 24. The subtraction circuit 24 calculates the difference between the lens position signal 111 and the driving current signal 112 outputted from the buffer amplifier 2 and applies a low-pass filter as a correction current signal 114 which is a moving speed signal indicating the speed of the focusing lens 15. output to the device 23.

On the other hand, the recording carrier 10 (information track) of the focusing lens 15
When calculating the speed relative to the recording medium 10, the relative speed of the focusing lens 15 with respect to the record carrier 10 can be obtained by smoothing (low-pass filtering) the speed pulse 113 outputted by the speed pulse generating circuit 22. If a low-pass filter that sufficiently removes high frequency components is used for 113, the high frequency components of the speed signal will not be obtained. Therefore, in this embodiment, after adding the speed pulse 113 and the corrected current signal 114 in the low-pass filter 23, low-pass filtering is performed to correct the high frequency component of the speed signal, and the speed signal 101 is Output. Since the corrected current signal 114 is used to compensate for high frequency components in the addition in the low-pass filter 23, the DC component may be cut (a capacitor 31 is connected in series to the signal line of the addition section). This makes it possible to remove the influence of the current offset of the power amplifier 26 or the external force constantly applied to the lens actuator 18. Therefore, the low-pass filter 23 reduces the It is possible to obtain a speed signal 101 indicating an accurate speed with the influence of reaction force etc. removed.

The optical head driving section 300 includes a phase compensation filter 27, a power amplifier 28, and a head positioner 29, and forms a servo loop together with the lens position detector 17 attached to the optical head 100 and the buffer amplifier 21 of the speed signal generating bag fi200. The lens position signal 111, that is, the optical head 10 is adjusted so that the positional deviation of the focusing lens 15 is small.
Move 0.

The phase compensation filter 27 is composed of, for example, a Leet-lag filter or the like, and receives the lens position signal 111 from the buffer amplifier 21 and performs phase compensation of the servo loop. The power amplifier 28 receives and amplifies the output signal from the phase compensation filter 27, and sends the optical head 10 to the positioner 29.
Supply current to move 0. With this configuration, it is possible to cause the optical head 100 to follow the focusing lens 15 so that the positional deviation of the focusing lens 15 is reduced.

Next, the operation of this embodiment will be explained.

If access to an information track different from the current location is requested, the position error (distance [)] from the current location to the target location is
A reference speed signal 102 is generated that indicates a speed that changes in response to the change in speed, and the focusing lens 15 is controlled to move according to the speed. The reference speed signal 102 is as shown in FIG.
As shown in a), it is specified that the focusing lens 15 is accelerated at a position far from the target position, and decelerated when it approaches the target position and the positional error becomes smaller. When accelerating the focusing lens 15, a positive current is sent from the power amplifier 26 of the speed signal generator 200, and when decelerating the focusing lens 15, a negative current is sent as a drive current signal 112 as shown in FIG. 2(b). , are supplied to the lens actuator 18. However, the current supplied to the lens actuator 18 includes supporting members 19a and 19b generated by the movement of the focusing lens 15.
The component that opposes the reaction force is included, and the component that substantially accelerates or decelerates the focusing lens 15 is indicated by the broken line in FIG. 2(b).

As the focusing lens 15 is accelerated or decelerated, the positional deviation of the focusing lens 15 with respect to the optical head 100 increases;
Since the optical head 1 follows and moves, the displacement of the focusing lens 15 is not large. However, during the acceleration or deceleration period, the positional shift of the focusing lens does not become zero, and a reaction force of the supporting members 19a, 19b is generated by the amount of the positional shift. In order to counter the reaction force of the supporting members 19a and 19b, extra current is supplied to the lens actuator 18, and as mentioned above, the current component originally used for acceleration and deceleration and the detected drive current A difference occurs between the signal 112 and the signal 112. A signal corresponding to the positional deviation of the focusing lens 15 is detected by the lens position detector 17 as a lens position signal 111 as shown in FIG. 2(C), and this lens position signal 111 is subtracted from the drive current signal 112. As a result, a corrected current signal 114 corresponding to the broken line portion shown in FIG. 2(b) described above, which is substantially a current component used for acceleration and deceleration of the focusing lens 15, is obtained. After that, the obtained correction current signal 114 and the speed pulse 113 indicating the speed of the focusing lens 15 with respect to the recording medium 10 are added, and then the low frequency is filtered to obtain the speed signal 101. If the addition and low-pass filtering are performed without removing the This results in excessive acceleration and deceleration. However, in this embodiment, after removing the positional deviation component of the focusing lens 12 from the drive current signal 112, addition with the velocity pulse 113 and low-pass filtering are performed, so the solid line in FIG. 2(d) A speed signal 101 similar to the reference speed signal 102 shown in the figure can be obtained, and ideal speed control can be performed.

[Effects of the Invention] As explained above, the present invention calculates the speed of the focusing lens by removing the positional deviation component of the focusing lens with respect to the optical head, and calculates the speed of the focusing lens and the speed emitted every time the focusing lens moves a certain distance. After adding the pulses, low-pass filtering is performed to obtain the speed signal of the optical head, so the influence of the reaction force of the support member of the focusing lens is removed, and a speed signal with high frequency components compensated for can be obtained. In an optical disk device that requires high-speed movement of a focusing lens and an optical head, there is an effect that stable and highly accurate information access can be performed more reliably.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the optical disc device of the present invention, and FIG. 2 is a diagram showing waveforms for explaining the operation of the optical disc device shown in FIG. 1. 10... Record carrier, 11... Semiconductor laser, 12... Lens, 13... Beam splitter, 14... Mirror, 15. ...Focusing lens, 16...Track error detector, 17
... Lens position detector, 18 ... Lens actuator, 19a, 19
b...Supporting material, 0.25...Differential amplifier, 1...
... Buffer amplifier, 2 ... Speed pulse generation circuit, 3 ... Low-pass filter, 24 ... Subtraction circuit, 6.28 ...・・・・・・Power amplifier, 7
... Phase compensation filter, 9 ... Head positioner, 0 ... Laser drive circuit, 1 ... Capacitor.

Claims (1)

[Claims] 1. An optical head in which a focusing lens that focuses light from a light source to form a light spot is movably supported by a support having spring characteristics, and further includes a driving source for moving the focusing lens. An optical disc device comprising: a lens position detector that detects a positional shift of the focusing lens with respect to the support portion of the support body; and a pulse generation circuit that outputs a predetermined speed pulse every time the focusing lens moves a certain distance with respect to the optical disc. a drive amount detector that detects a current value for the drive source to drive the focusing lens; and a drive amount detector that subtracts the positional deviation detected by the lens position detector from the current value detected by the drive amount detector. a subtraction circuit that generates a moving speed signal indicating the speed of the focusing lens; and a subtracting circuit that adds the moving speed signal generated by the subtracting circuit to the speed pulse to generate a relative speed signal of the focusing lens with respect to the optical disk; 1. An optical disc device comprising a speed signal generation device including a low-pass filter that performs low-pass filtering of a speed signal to generate a speed signal.