JP2001118258A - Optical information recording / reproducing device - Google Patents

Abstract

(57) [Summary] [Problem] Since a DC motor is driven by current drive after focus pull-in at a home position of an optical card,
In some cases, the movement speed is so large that tracking cannot be drawn into the target track. SOLUTION: When an optical head 204 accesses a target track from a home position, a DC motor 209 is driven by voltage control in an open control to relatively move the optical head 204 and the optical card 107, and a track crossing signal is generated. In the detected area, the drive of the DC motor 209 is switched to the current drive, and the optical head is moved to the target track while controlling the speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing apparatus for recording information on a recording medium having a plurality of tracks or reproducing the recorded information, and in particular, a track for accessing an optical head to a target track of the recording medium. It is about access.

[0002]

2. Description of the Related Art Various types of recording media, such as a disc, a card, and a tape, are conventionally known as a recording medium for optically recording information or reading recorded information. These optical information recording media include those that can be optionally recorded and reproduced, those that can be additionally recorded and reproduced,
Some can only be reproduced. In particular, the use of an optical card as a recording medium is expected to be expanded due to features such as ease of manufacturing, portability, and accessibility. Various types of optical information recording / reproducing devices for this optical card are provided.

In such an optical information recording / reproducing apparatus,
Recording and reproduction of information are performed while always performing auto tracking and auto focusing control. The recording of information on the recording medium is modulated according to the recording information, and the information beam is recorded as an optically detectable information pit row by scanning the information track with a light beam narrowed in a minute spot shape. In addition, reproduction of information from a recording medium
A low-power light spot that does not record on the medium is scanned over the information pit row of the information track, and reflected light or transmitted light from the medium is detected, and predetermined signal processing is performed using the obtained detection signal. Thus, the recorded information is reproduced.

FIG. 4 is a configuration diagram showing a typical example of an optical head used in such an optical recording / reproducing apparatus. In FIG. 4, a light beam emitted from a semiconductor laser 101 is collimated by a collimator lens 102 and is divided into a plurality of light beams by a diffraction grating 103. The split light beam passes through the polarizing beam splitter 104 and the quarter-wave plate 105, and the objective lens 1
At 06, the light is focused on the optical card 107 into a minute light spot. The reflected light from the optical card 107 is
6, 1/4 wavelength plate 105, polarizing beam splitter 10
4. Photodetector 109 via toric lens 108
Is detected by Reproduction and auto-focusing control (hereinafter, referred to as AF) are performed by using the 0th-order diffracted light split by the diffraction grating 103 among the detection signals of the photodetector 109, and ±
Auto tracking control (hereinafter referred to as A
T). An actuator 125 moves the objective lens 106 in the focusing direction and the tracking direction. AF is an astigmatism method, and AT is a three-beam method.

FIG. 5A is a schematic plan view of an optical card. A number of information tracks are arranged in parallel on the optical card 107, and some of them are T1, T2, T3,.
It is shown as This track is divided into tracking tracks tt1 to tt4. The tracking tracks tt1 to tt4 are grooves or tracks T1 to tt4.
T3 is formed of a substance having a different light reflectance, and is used as a guide for obtaining a tracking control signal. FIG.
(A) shows an example in which information is recorded or reproduced on the track T3. In this example, the 0th-order diffracted light 110 for recording, reproduction and AF is on the track T3, and the ± first-order diffracted lights 111 and 112 for AT are tracking tt3 and tt4, respectively.
It is located in. The reflected light from the diffracted lights 111 and 112 is detected by the AT light receiving element of the photodetector 109, and a tracking control signal is generated from the detection signal. Based on the signal, the 0th-order diffracted light 110 scans the track T3 correctly. AT control is performed. Each diffracted light 110, 111, 11
2 scans the optical card 107 in the horizontal direction on the drawing by a mechanism (not shown) while maintaining the same positional relationship under AF and AT control.

The scanning method includes a method of moving an optical system and a method of moving an optical card. In either method, the optical system and the optical card reciprocate relative to each other.
Non-constant speed portions occur at both ends of the optical card. FIG. 5B shows this state. The horizontal axis in FIG. 5B represents the horizontal direction of the optical card, and the vertical axis represents the relative scanning speed between the optical system and the optical card. Usually, an optical card 10
7 is used as a recording area. The home position HP shown in FIG. 5A is provided in an area without a track at the scanning end in the track direction, and is used as a reference position for track access. That is, focusing is performed at the home position HP, and then the optical head or the carriage on which the optical card is mounted is driven, so that the optical beam and the optical card are relatively moved in the track orthogonal direction, and the target beam is moved to the target track. Perform access.

FIG. 6 shows the diffracted lights 110 to 112 in FIG.
FIG. The 0th-order diffracted light 110 for recording, reproduction and AF is located at the center of the ± first-order diffracted lights 111 and 112 for AT and scans the center of the track T3. Shaded area 11
Reference numerals 3a, 3b, and 3c denote recording rows of the 0th-order diffracted light 110 of the semiconductor laser 101, which are generally called pits. Since the pits 113a, 113b, and 113c have different reflectances from the periphery of the other recording rows, when the light is scanned again with the weak light spot 110, the reflected light of the 0th-order diffracted light 110 becomes
Modulated by a, b, and c to obtain a reproduced signal. Also, A
The ± first-order diffracted lights 111 and 112 for T are irradiated to the periphery of the recording row and the tracking tracks tt3 and tt4, and the reflected light provides a tracking control signal.

FIG. 7 is a circuit diagram showing details of the photodetector 109 of FIG. 4 and a signal processing circuit. In FIG. 7, a photodetector 109 includes a four-divided photosensor 114, photosensors 115 and 11,
It consists of a total of six optical sensors. The light spots 110a, 111a, and 112a are respectively shown in FIG.
(A), each diffracted light 110, 111, 112 in FIG.
Represents reflected light. The light spot 110a is condensed on the four-divided optical sensor 114, and the light spots 111a, 112a
Are focused on the optical sensors 115 and 116, respectively. The sensor output in each diagonal direction of the four-divided sensor 114 is
17 and 118 are added.

The outputs of the adders 117 and 118 are similarly added by an adder 121 and output as an information reproduction signal RF. That is, the information reproduction signal RF is transmitted to the four-division optical sensor 11.
4 corresponds to the sum total of the light spots 110a condensed at 4.
Also, the outputs of the adders 117 and 118 are subtracted by the differential circuit 120 to become a focusing control signal Af. That is,
The focusing control signal Af is a difference between the sums of the four divided optical sensors 114 in the respective diagonal directions. Since the astigmatism method is well known in the literature, the description is omitted here. Further, the outputs of the optical sensors 115 and 116 are subtracted by the differential circuit 119 to become a tracking control signal At. Normally, the tracking control signal At is controlled so as to become zero, thereby performing tracking control for causing the light spot to follow the information track.

Here, in order to access the target spot on the optical card 107 to the light spot, a track crossing signal is generated when the light spot crosses the track on the optical card, and the track crossing signal is counted and obtained. A method is used in which the optical head and the optical card are relatively moved in the direction orthogonal to the track based on the count value. The track crossing signal is obtained by comparing the tracking control signal At with a constant voltage VL by a comparator and binarizing it.

FIG. 8 shows a tracking control signal At according to such a method and a track crossing signal TRC which is a binary output thereof. One pulse of the tracking crossing signal is output by one wave of the tracking control signal At. By counting this signal TRC, the relative movement distance between the light spot and the optical card can be measured. In addition, since the scanning speed can be detected by measuring the pulse interval of the track crossing signal by counting the clock pulse, the speed is controlled based on the obtained scanning speed and the relative moving distance to access the target track. .

FIG. 9 is a block diagram showing a configuration of a conventional optical card recording / reproducing apparatus. 9, first, when the optical card 107 is inserted into the apparatus, it is detected by a sensor (not shown) and notified to the MPU 201. The MPU 201 controls a motor drive circuit (not shown) to drive the loading motor, thereby introducing the optical card 107 into the apparatus and mounting the optical card 107 on the carriage 202. Also, the MPU 201
Controls the VCM drive circuit 219 to position the optical head 204 at the home position HP, which is the left end of the entire scanning area of the optical card in FIG. The optical head 204 is as shown in FIG. After that, the MPU 201 connects SW1 to the A side and gives a fixed command value to the D / A converter 221.
The corresponding voltage signal is supplied to the AT actuator driving circuit 2
16. The command value at this time is a value that does not cause a drive current to flow through the actuator 125 in the optical head 204, and 0 voltage is applied to the actuator 125 from the AT actuator drive circuit 216.

At the same time, the MPU 201
03, the semiconductor laser 101 is turned on, and the light spot from the optical head 204 is irradiated on the home position HP of the optical card 107. The reflected light from the optical card 107 is detected by the photodetector 109, and the signal processing circuit 205 generates a focus control signal Af based on the sensor output. The signal processing circuit 205 is the circuit shown in FIG. MPU2
In step 01, focus is pulled using the focus control signal Af so that the light beam is focused on the medium surface at the home position HP.

Next, the MPU 201 is
Is moved in the direction orthogonal to the track, and the optical head 204 accesses the target track of the optical card 107 for track access. Although there is no track between the home position HP and the recording area, the track access is performed as follows in order to relatively move the optical head 204 and the carriage 202 in this area. First, the MPU 201
Is the D / A converter 207 with SW2 connected to the B side.
Is given a fixed command value. The D / A converter 207 supplies a voltage signal corresponding thereto to the DC motor drive circuit 208,
The DC motor 209 is driven at a constant current. DC motor 2
09 is transmitted to the lead shaft 211 via the gear 210 and the lead pin 21 fixed to the carriage 202
By moving the carriage 2, the carriage 202 is moved in the track orthogonal direction.

Upon entering the recording area, a track crossing signal is obtained, and a track access is performed using the signal. That is, the tracking control signal At is generated by the signal processing circuit 205, and the tracking control signal At is
The value is converted to a value to generate a track crossing signal TRC as shown in FIG. The MPU 201 calculates the scanning speed based on the pulse interval of the track crossing signal, calculates the residual distance to the target track from the count value of the track crossing signal, and sets the control value based on the obtained scanning speed and the residual distance. Calculate,
The speed of the DC motor 209 is controlled. The control value of the MPU 201 is supplied to the DC motor drive circuit 208 via the D / A converter 207, and the speed of the carriage 2 is controlled while controlling the speed.
02 is moved.

When the optical head 204 reaches the target track, the MPU 201 switches SW1 to the B side, turns on the tracking servo, pulls the light spot into the target track, and starts tracking control. When the tracking servo is turned on, the tracking control signal At is sent from the signal processing circuit 205 to the actuator 12 via the phase compensator 216 and the AT actuator driving circuit 216.
5 to be in a tracking state. Also, MPU
201 switches SW2 to the A side, supplies the tracking control signal At to the DC motor drive circuit 208 via the phase compensators 214 and 217, and performs double tracking servo. That is, since the objective lens 106 shifts due to skew of the optical card or the like, the carriage 202 is driven based on the tracking control signal, and double tracking servo is performed so that the objective lens 106 is located at the center.

When the track access is completed, M
The PU 201 controls the VCM drive circuit 219 to drive a voice coil motor including a voice coil 218 and a magnet 217. By driving the voice coil motor, the optical head 204 moves in the track direction, and the optical head 20 moves.
The light spot of No. 4 is scanned on the target track. At this time, the track number of the optical card is read, and if it is confirmed that the track is the target track, the optical head 204 is further scanned to record or reproduce information. When recording information, the laser drive circuit 203 drives the semiconductor laser 101 in accordance with a recording signal, and performs recording by scanning an intensity-modulated light beam on a target track. When reproducing recorded information, a target light track is scanned with a reproducing light beam, and recording is performed by performing predetermined signal processing using an information reproducing signal RF generated by a signal processing circuit 205 in a reproducing circuit (not shown). Reproduce information.

Next, when there is a scanning command, the MPU 201 moves the light beam to the designated track. This includes a seek method for moving the carriage 202 and the objective lens 1.
There is a track jump method for moving the 06. The seek method is a method in which the carriage 202 is moved while performing speed control using a track crossing signal, and is exactly the same as described above. Here, a description will be given assuming that the movement is performed by the track jump method. The MPU 201 switches SW2 to the B side, and at the same time gives a fixed command value to the D / A converter 207, and the DC motor drive circuit 208
0 voltage is applied to 9.

At the same time, the MPU 201 switches SW1 to the A side, turns off the tracking servo loop, and
A jump drive signal is supplied to the A converter 221. The jump drive signal is composed of a constant command value for acceleration and a subsequent constant command value having different polarities for deceleration. When a jump drive signal is supplied, the actuator 1
The objective lens 106 moves in the direction crossing the track by driving the drive 25, and at this time, a track crossing signal is output from the comparison circuit 213 and supplied to the MPU 201. MPU2
01 counts the track crossing signal, and when it reaches the target track, switches SW1 to the B side and turns on the tracking servo. At the same time, switch SW2 to A side,
Move to heavy tracking servo. Next, the optical head 20
4 is scanned to record / reproduce information on the target track.

Next, the speed control method will be described.
FIG. 10 is a flowchart showing the speed control process. This routine is executed at regular intervals. In FIG.
First, a target moving speed _VT is calculated in S1. Assuming that the distance X from the movement start position (speed control start position) to the target track is X = X _i , the current position is X ₀ , and the position proportional coefficient is K _K , the target movement speed V _T is V _T = (X _i obtained in the -X ₀₎ · _K K.

Next, in S2, the target speed V _T and the current speed V
_The control amount ε is calculated using ₀ . The current speed V ₀ is obtained from the pulse interval of the track crossing signal. The control amount ε is obtained by ε = (V _T −V ₀ ) · K _P. K _P is a proportional gain. In S3, the control amount is supplied to the D / A converter 207, and the DC motor 209 is controlled.
Drive. Thus, one speed control process is completed, and thereafter the same speed control process is performed at regular intervals. FIG. 11 shows a speed profile in this case. The horizontal axis is the distance X,
The vertical axis is the target speed V. The target speed decreases as the target track approaches. Speed control is performed so as to follow the target speed. When the target speed becomes 0, the vehicle reaches the target track, and the speed control is completed.

[0022]

However, in the above-described conventional track access method, when speed control is performed using a track traversing signal, a DC motor drive method uses a current drive which is small in control delay and advantageous in control. Therefore, the DC motor is driven by the constant current drive even after the focus is pulled at the home position HP. Therefore, if there is a variation in the characteristics of the DC motor or the mechanical unit load, a change in the motor characteristics due to an environmental temperature or a change over time, or a change in the mechanical unit load, the moving speed fluctuation is large. In some cases, driving became impossible.

FIG. 12 is a diagram showing a torque-rotational speed (TN) characteristic and a torque-driving current (TI) characteristic of the DC motor when the DC motor is driven by current driving.
The horizontal axis represents torque (or load), the vertical axis (left side) represents the rotation speed (moving speed of the carriage), and the vertical axis (right side) represents the drive current. Hereinafter, speed fluctuations due to load fluctuations (due to load variations, environmental temperatures, and changes over time) of the mechanical unit will be described with reference to FIG. Now, assume that the TN characteristic when the voltage V applied to the DC motor is Va is TN (V = Va),
Let L1 be the load characteristic of the entire mechanism.

Here, when the DC motor is driven at a constant current of I = Ia, a torque of Ta is generated as shown in FIG. 12, and when the load is L1, the rotation speed (movement speed) is N = Ia.
It becomes Na. When the load changes to L2, the rotation speed becomes N = Nc, and the rotation speed changes greatly from Na to Nc. However, if the moving speed is too low, the moving time is long and the device becomes inconvenient to use. If the moving speed is too low to operate, a normal operation becomes impossible. Also, if the moving speed is too high, after detecting the track crossing signal, even if an attempt is made to access the target track by speed control, the speed cannot be sufficiently reduced when reaching the target track, and the target track will be switched when switching to tracking control. In some cases, tracking could not be pulled in.

FIG. 13 is a graph showing torque-rotation speed (TN) characteristics when the DC motor is driven by voltage driving. The TN (V = Va) characteristics, load characteristics and load fluctuation are the same as those in FIG. FIG. 13 for voltage drive
When the load changes from L1 to L2 as shown in FIG.
a changes to Nb. Therefore, the rotation speed fluctuation rate Ri in the case of FIG. 12 is (Na−Nc) / Na, and the rotation speed fluctuation rate Rv in the case of FIG. 13 is (Na−Nb) / Na. Then, Rv <Ri. The rate of change of the rotational speed depends on the slope of the TN characteristic, the slope of the load characteristic, and the range of fluctuation. However, when the slope of the load is large, the speed fluctuation is smaller in constant voltage driving than in constant current driving. . As described above, when the DC motor is driven by the current drive, the speed fluctuation becomes large, so that there is a problem that the relative movement cannot be performed or the tracking cannot be drawn into the target track as described above.

According to the present invention, in consideration of the above-described conventional problems, the movement from the home position is driven by voltage control in an open control, so that the relative movement speed fluctuation in the open control is reduced and the target track is reliably moved to the target track. It is an object of the present invention to provide an optical information recording / reproducing device which can be accessed.

[0027]

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical head for recording or reproducing information on a recording medium provided with a home position serving as a reference for track access near a recording area composed of a plurality of tracks; Means for relatively moving the optical head and the recording medium in the cross-track direction,
Means for detecting a track traversing signal when the optical head crosses a track; detecting a relative moving speed of the optical head and the recording medium based on the track traversing signal; and detecting a relative moving speed and a residual distance to a target track. An optical information recording / reproducing apparatus comprising: means for controlling a relative moving speed of the optical head and a recording medium based on the target speed, wherein the optical head comprises means for switching the moving means between voltage drive and current drive. When the target track is accessed from the home position, the optical head and the recording medium are moved relative to each other by driving the moving means under voltage control with open control, and in the area where the track crossing signal is detected, Switching the driving of the moving means to current driving,
The optical information recording / reproducing apparatus is characterized in that the optical head is moved to a target track while controlling the speed by the speed control means.

[0028]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the first embodiment of the optical information recording / reproducing apparatus of the present invention. In FIG. 1, the same parts as those of the conventional apparatus of FIG. In FIG. 1, a DC motor drive circuit 220 is a drive circuit that drives a DC motor 209 and moves a carriage 202 on which the optical card 107 is mounted in a direction orthogonal to the tracks. When accessing the target track from the home position HP of the optical card 107, the MPU 201 outputs a switching signal Q to the DC motor drive circuit 220, and switches the drive of the DC motor 209 to voltage drive. Therefore, the DC motor drive circuit 220 drives the DC motor 209 from the home position HP by voltage control under open control, thereby controlling the carriage 202.
To move.

When the carriage 202 moves and enters a region where a track crossing signal is detected, the MPU 201 outputs a switching signal Q to the DC motor driving circuit 220,
The drive of the DC motor 209 is switched to the current drive. Therefore, in the area where the track crossing signal is detected, the drive of the DC motor 209 is switched to the current drive, the moving speed is detected based on the track crossing signal as described above, and the residual speed between the current moving speed and the target track is detected. The optical head is moved to the target track by moving the carriage 202 while controlling the speed based on the target speed corresponding to the distance. The method of speed control is the same as the method of FIGS.

Next, the track access operation of this embodiment will be described with reference to FIG. FIG. 2A is a plan view of the optical card when the horizontal axis is the short direction and the vertical axis is the long direction. FIG. 2B shows a speed profile at the time of track access. The horizontal axis in FIG. 2B is the distance from the home position HP, and the vertical axis is the moving speed. Let _Xt be the target track to be accessed. The optical head 2
04 is already located at the home position HP.

First, when there is a track access command, M
As described above, the PU 201 outputs the switching signal Q to the DC motor driving circuit 220, and switches the driving of the DC motor 209 to the voltage driving. The MPU 201 sets SW2 to B
And supplies a predetermined command value to the D / A converter 207 at the same time. As a result, the D / A converter 207 has a DC
A voltage signal corresponding thereto is supplied to the motor drive circuit 220, and the DC motor 209 is driven by constant voltage driving, and is driven by open control. By driving the DC motor 209, the carriage 202 moves from the HO position HP (X = 0) of the optical card 107 in the direction orthogonal to the track.

As described above, when the carriage 202 moves in the track orthogonal direction and the light beam of the optical head 204 enters the recording area of the optical card 107, the comparison circuit 213 outputs a track crossing signal. The track crossing signal is
First, it is output between the tracking tracks tt1 and tt2. When the track crossing signal is output, the MPU 201 outputs a switching signal Q to the DC motor driving circuit 220, switches the driving of the DC motor 208 to current driving, and performs driving by speed control. That is, executes the speed control process in FIG. 10 at predetermined time intervals, performs speed control so the carriage 202 as shown in FIG. 2 (b) is moved to follow the target speed L _x. When the light beam of the optical head 204 reaches the target track X _t, the MPU 201 switches the SW1 to the B side, performs pull tracking. SW2
To the A side to perform double tracking servo.

Next, the MPU 201 controls the VCM driving circuit 2
By controlling the voice coil motor 19, the optical head 204 is moved in the track direction. At this time, the track number is read, and after confirming that the track is the target track, information is continuously recorded on the target track,
Alternatively, the recorded information is reproduced. The determination as to whether or not the track crossing signal is output may be made by detecting the pulse interval of the track crossing signal and determining that the track crossing signal cannot be obtained if the predetermined time or more. When returning to the home position HP such as when the optical card is ejected, the light beam irradiation is turned off and the movement in the cross-track direction is performed by open control. Since the light beam is also turned off in the recording area of the optical card and a track crossing signal cannot be obtained,
Drive by open control. For this reason, it is possible to save power required for light beam irradiation, focusing control, and the like.

FIG. 3 is a circuit diagram showing an example of the DC motor drive circuit 220. R1 to R6 are resistors, Rs is a current detection resistor, SW4 is a switch, and 301 and 302 are power operational amplifiers. Power operational amplifiers 301 and 302
A DC motor 209 is connected between the outputs of. Also,
P is a control signal from the MPU 201 (or the phase compensator 217), and Q is a switching signal of the switch SW4, and switches between voltage driving and current driving as described above. The + terminals of the power operational amplifiers 301 and 302 have the power supply voltage V of 1
/ 2 voltage. Here, the DC motor 20
The coil impedance of No. 9 is Z, R1 to R6 have the same resistance value, and at the time of open control, SW4 is opened by a switching signal from the MPU 201. At this time, M
When a control signal from the PU201 and _{(V / 2 + V i)} , a voltage applied between V _1, V ₂ is 2V _i becomes, D
C voltage V _m to be applied to the motor 209 becomes _{V m = 2V i × (Z} / (Z + R S)). When _{R s << Z, V m =} 2V i becomes, the voltage driving circuit.

On the other hand, during speed control, SW4 is closed. The control signal from the MPU 201 is (V / 2 + V
_i ), the current I flowing through the DC motor 209 becomes I = V _i / R _s , and it becomes a current drive circuit. Thus, the MPU 201
The DC motor 209 can be switched between the voltage drive and the current drive by supplying a switching signal from the controller and turning on and off the switch SW4.

In the above embodiment, the DC motor 2
Although it has been described that a predetermined command value is given to the D / A converter 207 in the open control of the step 09, the moving speed is detected from the interval of the track crossing signal by changing the voltage value in the case of the voltage drive in advance when the apparatus is adjusted. Alternatively, a voltage value at a predetermined moving speed may be obtained, a command value corresponding to the voltage value may be stored in an EEPROM, and voltage driving may be performed using the value when the apparatus is operating. Similarly, when the power of the apparatus is turned on, a command value corresponding to a predetermined moving speed may be obtained and stored in a volatile memory such as a RAM, and the voltage driving may be performed using the value during open control.

In the embodiment, the carriage on which the optical card is placed is moved in the direction perpendicular to the track. However, the optical head may be moved in the direction perpendicular to the track, or a DC motor may be used as a drive source for moving the carriage. Although it is used, a voice coil motor or the like may be used. Furthermore,
Although the voltage drive / current drive is switched by the switching signal using the same drive circuit, different drive circuits may be used. In the case of the drive circuit of FIG. 3, an error occurs in the voltage drive due to the presence of the current detection resistor Rs when switching to the voltage drive. However, a switch is connected in parallel with the resistor Rs, and the switch is turned on during the voltage drive. By doing so, an error can be removed and accurate voltage driving can be performed. Further, the predetermined voltage signal is supplied by using the D / A converter at the time of driving at a constant voltage. However, a constant voltage may be supplied to the DC motor by switching with a switch or the like using a constant voltage source.

[0038]

As described above, according to the present invention, the optical head in the open control is driven by driving the moving means under the open control by the voltage drive in the area where the track crossing signal from the home position cannot be obtained. And fluctuations in the moving speed of the recording medium can be reduced, and the moving speed becomes small and the relative movement between the optical head and the recording medium cannot be performed, or the moving speed increases and the tracking cannot be drawn into the target track. The optical head can surely access the target track without causing a situation.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an optical information recording / reproducing apparatus of the present invention.

FIG. 2 is a diagram for explaining a track access operation of the embodiment of FIG. 1;

FIG. 3 is a circuit diagram illustrating an example of a DC motor drive circuit according to the embodiment of FIG. 1;

FIG. 4 is a diagram showing an example of an optical system of a conventional optical card recording / reproducing apparatus.

FIG. 5 is a diagram illustrating a relative scanning speed on a recording surface of an optical card and a recording area of the optical card.

FIG. 6 is a diagram showing a light spot on an optical card.

FIG. 7 is a circuit diagram showing an example of a signal processing circuit of a conventional optical card recording / reproducing device.

FIG. 8 is a diagram showing a tracking control signal and a track crossing signal when the optical head crosses a track.

FIG. 9 is a block diagram showing a conventional optical card recording / reproducing apparatus.

FIG. 10 is a flowchart showing speed control at the time of track access.

FIG. 11 is a diagram showing a speed profile at the time of track access.

12 is a diagram illustrating torque-rotation speed characteristics and torque-drive current characteristics in the case of current driving of the DC motor in FIG. 9;

FIG. 13 is a diagram showing torque-rotation speed characteristics in the case of voltage driving of the DC motor of FIG. 9;

[Explanation of symbols]

 Reference Signs List 101 semiconductor laser 106 objective lens 107 optical card 109 photodetector 201 MPU 202 carriage 204 optical head 216 actuator drive circuit 205 signal processing circuit 207, 221 D / A converter 209 DC motor 213 comparison circuit 214, 217 phase compensation circuit 216 AT Actuator drive circuit 219 VCM drive circuit 220 DC motor drive circuit SW1, SW2 switch

Claims (3)

[Claims] An optical head for recording or reproducing information on or from a recording medium having a home position serving as a track access reference near a recording area including a plurality of tracks; Means for moving in the cross-track direction, means for detecting a cross-track signal when the optical head crosses a track, detecting relative movement speed between the optical head and the recording medium based on the cross-track signal, Means for controlling a relative moving speed of the optical head and the recording medium based on a target speed corresponding to a residual distance to a target track, wherein the moving means is driven by voltage and current. When the optical head accesses the target track from the home position, the moving means is driven by voltage driving. The optical head and the recording medium are moved relative to each other by driving under the open control. In an area where the track crossing signal is detected, the driving of the moving means is switched to current driving, and the speed is controlled by the speed control means. An optical information recording / reproducing apparatus, wherein the optical head is moved to a target track while performing control. 2. The voltage driving is performed by a constant voltage driving,
2. The optical information recording / reproducing apparatus according to claim 1, wherein the value of the constant voltage is measured at the time of adjustment and stored in a memory. 3. The voltage driving is performed by a constant voltage driving,
2. The optical information recording / reproducing apparatus according to claim 1, wherein the value of the constant voltage is measured when the apparatus is powered on and stored in a memory.