JPH0516105B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an optical recording/reproducing device for optically recording and reproducing information on a disc-shaped recording medium (hereinafter abbreviated as a disk), and particularly relates to an optical recording/reproducing device for optically recording and reproducing information on a disk-shaped recording medium (hereinafter abbreviated as a disk). The present invention relates to a means for automatically returning an optical head for recording and reproducing to a preset radial reference position (hereinafter referred to as a zero position) on a disk at the start of reproduction.

[Technical background of the invention and its problems]

Generally, in this type of optical recording/playback device, when recording or playback is started, the optical head is temporarily returned to the zero position on the disk, that is, the innermost or outermost position of the recording area, and the information is recorded from that position. Or, it is configured to start a playback operation. In this case, the conventional zero position return means fixedly sets the zero position near the optical head movement limit position on the disk center side or the disk periphery side in the optical head movement mechanism, and returns the optical head when the start switch is turned on. was directly moved to the above-mentioned zero position and stopped at that position.

However, the conventional zero position return means described above has the following problems. In other words, since the optical head is directly moved to a fixedly set zero position with respect to the optical head movement mechanism, the return time varies depending on where the optical head is before returning to the zero position. The control output had to be adjusted depending on the length of the path. This has resulted in a drawback that the configuration of the control system is complicated.

[Purpose of the invention]

The present invention has been made based on such circumstances, and its object is to provide an optical recording/reproducing apparatus that can be moved to the zero position by a control system with a simplified configuration.

[Summary of the invention]

The present invention provides an optical recording and reproducing apparatus for moving an optical head for recording and reproducing information on a disc-shaped recording medium to a predetermined radial reference position of the disc-shaped recording medium prior to recording and reproducing operations. means for moving the optical head in a radial direction on the disc-shaped recording medium, constant speed movement control means for outputting a control signal to the moving means for moving the optical head at a constant speed, and a control signal for the constant speed movement control means. mark detection means for detecting that the optical head has reached a position mark provided along the movement path of the optical head when the optical head moves based on the position mark; radial reference position movement control for reversing the moving direction of the optical head and outputting a movement signal to the moving means to move the optical head by a distance between the position mark and the predetermined radial reference position; It is characterized by having the means.

[Embodiments of the invention]

The present invention will be explained in detail below with reference to embodiments shown in the drawings.

FIG. 1 is a block diagram showing the electrical configuration of one embodiment of the present invention. Reference numeral 1 shown at the left end in FIG. 1 is a disk rotated at a constant speed by a spindle motor (not shown), and 2 is a disk that performs focusing control and tracking control for various information such as image information on the disk 1. It is an optical head equipped with an actuator that records and reproduces information in a circular or spiral manner. Reference numeral 3 denotes a carriage that is integrated with the optical head 2 and is provided to reciprocate linearly in the direction indicated by the arrow in the figure, that is, in the radial direction of the disk. Reference numeral 4 denotes a voice coil motor ( (hereinafter abbreviated as VCM). 5
is a glass scale for positioning the optical head which is fixed to the base of the apparatus (not shown) in parallel to the moving direction of the optical head 2.
Limit position marks 5a and 5b are provided near both ends of this glass scale 5, and these marks 5
A scale 5C with a constant pitch is provided between a and 5b. 6 is a first photo sensor for detecting the scale 5C on the scale, and 7 is a second photo sensor having two detection terminals arranged in parallel in the width direction of the scale 5 in order to read the marks 5a and 5b on the scale. It is a photo sensor. These first and second photo sensors 6, 7 are fixed to the carriage 3 so as to move together with the optical head 2.

FIGS. 2a and 2b are a plan view and a partially enlarged view showing the scale 5 in detail. As shown in Figures 2a and b, the scale 5C consists of a linear scale scale LS1 carved at a constant pitch PA along the longitudinal direction of the scale 5, and a linear scale scale LS1 carved at a small pitch PB which is further divided into four parts of this LS1. It consists of scale graduation LS2. In this example, the pitch PA of LS1 is
The pitch is 80μm, and the pitch PB of LS2 is 20μm.
It is set equal to the movement pitch of the carriage 3 by the VCM 4.

On the other hand, an inner limit position mark 5a is provided at the upper left end of the scale 5 in the figure, and an outer limit position mark 5b is provided at the upper right end in the figure. The mark 5a consists of two parts IGB1 and IGB2, and the mark 5b consists of two parts OGB1 and OGB2. The IGB1 and IGB2 are placed at the optical head movement limit position in the second direction on the center side of the disk 1, and the OGB1 and OGB2 are placed at the optical head movement limit position in the second direction on the periphery side of the disk. The parts are aligned with precision.

Let's return to Figure 1. As shown by the thick arrow at the right end of FIG. 1, data indicating the zero position, that is, the return amount, is given to the instruction register 11 from a setting switch (not shown) or the I/O of disk 1, etc., and this data is stored in the register 11. . Here, the zero position is the initial setting position that the optical head 2 should be located with respect to the disk 1 at an initial stage before it starts recording or reproducing information on the disk 1. is the position at which point C in FIG. 3 is detected. Further, the data indicating the zero position, that is, the return amount, is distance information from the optical head movement limit position on the center side or the peripheral side of the disk 1 to the zero position. In this embodiment, the photo sensor 7 (7a, 7b) This is the moving distance (number of scales) n of the optical head from the position where the point B in the figure, that is, the boundary point between the marks IGB1 and IGB2, is detected to the position where the photo sensor 6 detects the point C.

The explanation returns to FIG. 1 again. When the start switch 12 shown in the lower right of FIG.
A pulse of a certain width is subtracted from the counter 15.
Given to the SET pin. Therefore, zero position data n, which is the content of the instruction register 11, is set in the subtraction counter 15. This data n is converted into analog data by the D/A converter 16, and the polarity of this data is determined by the output of the polarity inversion register 17 in the controller 13. At this point, the polarity reversal register 17 has been reset by the signal from the start switch 12, so the D/A converter 16 receives a polarity command to move the optical head 2 toward the center of the disk 1. It is given. Therefore, the digital data input to the D/A converter 16 is converted into a speed instruction analog signal for moving the optical head 2 toward the center of the disk, and the digital data is input to the error amplifier 18.
is supplied to the side input end.

On the other hand, the actual speed signal of the optical head 2 is applied to the input terminal on the side of the error amplifier 18, but since the optical head 2 is in a stopped state in the initial state, the level of the actual speed signal is zero level. .
As a result, the output voltage of the error amplifier 18 rises all at once, and one input terminal 1 of the analog switch 19
Added to 9a.

At this point, the analog switch 19 is set to the speed control side terminal 19a. Therefore, the output voltage of the error amplifier 18 is supplied to the power amplifier 20 via the analog switch 19. Therefore, power for driving the carriage is supplied from the power amplifier 20 to the VCM 4, and the optical head 2
starts moving toward the center of disk 1. In accordance with this, the first photo sensor 6 successively reads LS1 and LS2 of the scale 5C on the scale 5. This successive scale detection signal is amplified by an amplifier 21 and then converted into a first speed signal through a differentiation circuit 23 and a filter 24 of an actual speed detection circuit 22. This first speed signal is ON at this point.
It is supplied to one input of the mixer 26 via the analog switch 25 which is in the active state. Note that the analog switch 25 and the analog switch 19 are controlled by the output of the speed/position register 27 of the controller 13, but this speed/position register 27 is initially
2, and its output level is "0", so it is in the above state.

On the other hand, a current value proportional to the output voltage of the power amplifier 20 is detected by a current detection resistor provided in the power amplifier 20, and the detection signal is supplied to the integration circuit 28 of the actual speed detection circuit 22 and integrated. Thereafter, it becomes a second speed signal through a filter 29 and is input to the other input terminal of the mixer 26.

Therefore, at this point, the actual speed signal output from the actual speed detection circuit 22 is the sum of the first actual speed signal and the second actual speed signal in the mixer 26. The actual speed signal output from the mixer 26 is input to the side terminal of the error amplifier 18.

Thus, VCM4 is sped up to reduce the difference between the input voltages of error amplifier 18. And VCM4
When the speed of the VCM 4 reaches the speed instructed by the speed instruction analog signal, the speed increase command from the error amplifier 18 becomes zero, and the power supplied to the VCM 4 becomes constant. Therefore, from now on, the speed of the VCM 4 is controlled so that it drives the carriage 3 at a constant speed.

By performing the speed control as described above, the optical head 2 moves toward the center of the disk 1 at a constant high speed. Along with this, the first and second
The photo sensors 6 and 7 move in the direction shown by the arrow in FIG. When the optical head 2 reaches the movement limit position on the center side of the disk 1, each element 7a, 7b of the photo sensor 7 sequentially detects the marks IGB1, IGB2. At this time, the output levels of each element 7a and 7b are "0" and "0" in the D area shown in FIG. 3, "1" and "0" in the E area, and "1 and 1" in the F area, respectively. change. This output is amplified by the amplifier 30 in FIG.
The signal is decoded by the controller 13 and supplied to the controller 13. This point will be specifically explained below.

Now, if the photo sensor 7 enters the E region, "1" and "0" are detected first, but in this embodiment, the first detected "1" and "0" are not output from the decoder 32. I have to. Next, the photo sensor 7 enters the F area and becomes "1".
When “1” is detected, this detection power is applied to the decoder 3.
2 to polarity inversion register 1 in controller 13
It is added to the SET terminal of 7. As a result, the polarity inversion register 17 is brought into a set state, and the output polarity of the D/A converter 16 is inverted by its output. Since the polarity of the speed instruction analog signal output from the D/A converter 16 is thus reversed, an amplification command in the opposite direction is given to the power amplifier 20. Therefore, the VCM 4 operates to move the optical head 2 in the opposite direction to that in which it has been moving, that is, from the center of the disk 1 toward the periphery. As a result, when the photo sensor 7 enters the E area again and detects "1" and "0", this detection force is transferred to the D-
Added to FF33's CK terminal. At this time D-
The D terminal of the FF 33 is supplied with a high level signal "1" from the polarity inversion register 17 which is in the set state. Therefore, D-FF33 is inverted,
A high level signal "1" is applied to one input terminal of the AND gate 34.

On the other hand, the scale detection signal detected by the photo sensor 6 is amplified by the amplifier 21 and then converted into a rectangular wave by the waveform shaping circuit 35 and supplied to the other input terminal of the AND gate 34. Thus, the scale detection signal is input from the AND gate 34 to the CK terminal of the subtraction counter 15 as a subtraction clock signal from the time when "1" and "0" are detected after the detection of "1" and "1". Therefore, immediately after the optical head 2 starts moving in the opposite direction, the countdown of the position data n set in the subtraction counter 15 starts. Along with this, the speed command analog signal which is the output of the D/A converter 16 also gradually decreases, and the VCM 4 decelerates. Subtraction counter 15
When the contents of VCM 4 become zero, the VCM 4 becomes almost stopped.

The curve in FIG. 3 shows the operation of the optical head 2 described above. That is, in FIG. 3, G is the position of the optical head 2 before returning to the zero position, and ν is
It shows the speed of the VCM 4, that is, the moving speed of the optical head 2. The optical head 2 whose speed has been increased from the position G reaches the maximum speed based on a preset speed instruction analog signal, and then is controlled at a constant speed. And position H corresponding to point B on scale 5
When the speed reaches , an analog signal indicating the speed in the opposite direction is given, and after stopping suddenly, the robot is accelerated in the opposite direction and moves. Immediately after that, the speed is gradually decelerated and almost comes to a stop at zero position I corresponding to point C on the scale 5.

The explanation returns to FIG. 1 again. When the content of the subtraction counter 15 becomes zero, a zero detection signal notifying this is given to the timing circuit 36 in the controller 13. This timing circuit 36 delays the zero detection signal by a certain amount of time necessary to stabilize the control system, and then registers the speed/position register 27 in the same controller 13 at a predetermined timing.
It is applied to the SET input terminal to put this register 27 into the set state. When the speed/position register 27 enters the set state, it outputs a high level signal "1", switches the analog switch 19 from the speed control side terminal 19a to the position control side terminal 19b, and also switches the analog switch 25 in the actual speed detection circuit 22. OFF
state. Control of the optical head 2 is thus switched from speed control to position control. As a result, the power amplifier 20 is given a position control signal from the position servo circuit 37. The position servo circuit 37 receives a scale detection signal from the amplifier 21 and the actual speed detection circuit 2.
The actual speed signal from 2 is supplied. However, in this case, the analog switch 25 is OFF for the actual speed signal.
Since it is in this state, only the second speed signal is sent through the integrating circuit 28 and the filter 29.

Now, considering the moment when the output of the subtraction counter 15 becomes zero, the optical head 2 will move forward slightly due to the inertia of the VCM 4 and the like at the next point in time. At this time, the photo sensor 6 continues to move through several scale marks beyond the point C of the scale 5C corresponding to the zero position. A signal corresponding to the successive scales is applied to the position servo circuit 37 via the amplifier 21. Therefore, a backward drive command is applied to the power amplifier 20 in accordance with the number of consecutive graduations. For this reason
VCM4 operates in the opposite direction. On the other hand, the current value signal obtained by the current detection resistor of the power amplifier 20 is integrated and given to the position servo circuit 37 as a second actual speed signal. Thus, when the moving speed of the optical head 2 is high, a large reverse power is generated.
It is controlled so that it is given to VCM4. As a result, the optical head 2 approaches the zero position while vibrating in forward and reverse directions around the zero position I.

On the other hand, the scale detection signal outputted from the waveform shaping circuit 35 at the time of vibration is transmitted to the f/V converter 38.
supplied to The f/V converter 38 converts the speed change component, that is, the frequency f, included in the scale detection signal during the vibration into a voltage signal, and supplies the voltage signal to the determination circuit 40 in the controller 13. The determination circuit 40 determines whether the output from the f/V converter 38 is determined by a preset upper limit value ν2 and lower limit value ν1 as shown in FIG.
is within the range and the period exceeds a certain period T, an output “1” is given to one input terminal of the AND gate 41. The other input terminal of the AND gate 41 is supplied with the zero detection signal output from the subtraction counter 15 described above. As a result, the AND gate 41 sends out an END signal indicating that the zero position return operation has been completed.

Figure 4 is a diagram showing the above position control.
FIG. 3 is a diagram in which time is plotted on the horizontal axis and optical head movement speed is plotted on the vertical axis. In FIG. 4, J is the position control start point, and by performing position control from this J point, the optical head 2 at K point is ν1
and ν2, and position control ends at point M.

In this embodiment described above, the relative positional relationship between the marks IGB1 and IGB2 provided on the scale 5 and the optical head movement limit position can be made to match with high accuracy regardless of the various conditions that the disk 1 has. . Therefore, by setting the zero position data n in advance according to the conditions on the disk side, it is possible to easily and accurately set the zero position to a constant position that is optimal for the disk based on the head movement limit position. . When returning to the zero position, the scale 5c on the scale 5 is continued and the subtraction counter 15 counts down.
Since the set return amount is returned and the zero position is held by the position control means when the zero position is reached, highly accurate zero position return can be performed. Furthermore, no matter what position the optical head 2 is in before returning to the zero position, only relatively simple speed control is required until it reaches the movement limit position on the disk center side. Relatively complex and fine controls such as deceleration control and position control may be performed from the time when movement is started in the opposite direction from the movement limit position. In this case, the zero position data, that is, the return amount n, is variably set to match the conditions on the disk side, but it is set without direct relation to the position of the optical head 2 before the return operation starts, that is, the length of the total length of the return path. It is possible. Therefore, the control operation is simplified, and the configuration of the control system can be simplified accordingly.

Note that the present invention is not limited to the above-mentioned embodiment. For example, in the embodiment described above, the zero position is set at the center of the disk 1, but it may be set at the periphery of the disk 1.
However, in that case, marks corresponding to marks IGB1 and IGB2 should be provided on the edge of the disk periphery on the scale 5, and marks corresponding to marks OGB1 and CGB2 should be provided on the edge of the scale 5 on the disk center side. There is a need.

Further, in the above embodiment, the scales and marks on the scale 5 are optically read, but magnetic, electrostatic or other reading means may be used.

〔Effect of the invention〕

As explained above, according to the present invention, in order to move the optical head to the zero position, the optical head is first moved at a constant speed to a position mark provided along the movement path. Next, it is moved a predetermined distance from this position mark to the zero position.

In this case, the control system is simplified because it moves at a constant speed to the position mark. In addition, instead of adjusting the control output according to the length of the return path as in the conventional case, it is sufficient to always move by a predetermined rectangular distance, so it is possible to configure a simple control system.

[Brief explanation of drawings]

Figures 1 to 4 are diagrams showing an embodiment of the present invention. Figure 1 is a block diagram mainly showing the electrical configuration of the apparatus of the present invention, and Figures 2a and 2b are diagrams showing the glass scale of Figure 1. A more detailed plan view and partially enlarged view, and Figure 3 show the correspondence between the scale and marks on the glass scale and the position of the optical head, as well as a diagram showing the relationship between the position and speed of the optical head. FIG. 4 is a diagram showing the relationship between the moving speed of the optical head and time when speed control is shifted to position control. 1...disk, 2...optical head, 3...
Carriage, 4...VCM, 5...Glass scale, 6,7...Photo sensor.

Claims (1)

[Scope of Claims] 1. An optical recording/reproducing device in which an optical head for recording/reproducing information on a disc-shaped recording medium is moved to a predetermined radial reference position of the disc-shaped recording medium prior to recording/reproducing operations, means for moving the optical head in a radial direction above the disc-shaped recording medium; constant speed movement control means for outputting a control signal to the moving means for moving the optical head at a constant speed; and constant speed movement control means for moving the optical head at a constant speed. mark detection means for detecting that the optical head has reached a position mark provided along a movement path of the optical head when the optical head moves based on a control signal of the optical head; a radial reference for outputting a movement signal to the moving means for reversing the moving direction of the optical head and moving the optical head by a distance between the position mark and the predetermined radial reference position when the optical head is moved; An optical recording/reproducing device comprising: a position movement control means;