JP2001118259A - Optical information recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such problem that, when a moving speed is high in the case of open control and a target track is near, it is impossible to reduce the speed and pull in tracking into the target track. SOLUTION: An optical head 204 is moved to the target track after having been moved relatively to the optical card 107 by open control, having changed over the speed control to that by a speed control signal in the area where a track traverse signal is detected, and also the optical head is moved to a prescribed track.

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. 7 is a configuration diagram showing a typical example of an optical head used in such an optical recording / reproducing apparatus. In FIG. 7, a light beam emitted from a semiconductor laser 101 is collimated by a collimator lens 102 and split 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. 8A 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. 8B shows this state. The horizontal axis in FIG. 8B 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. 8A 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. 9 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. 10 is a circuit diagram showing details of the photodetector 109 of FIG. 7 and a signal processing circuit. In FIG. 10, a photodetector 109 includes a four-divided optical sensor 114, an optical sensor 115,
It consists of 116 optical sensors in total. Further, the light spots 110a, 111a, and 112a correspond to the respective diffracted lights 110, 111, and 1 in FIGS.
12 represents the reflected light. The light spot 110a is condensed on the four-divided optical sensor 114, and the light spots 111a, 111
2a is focused on the optical sensors 115 and 116, respectively. 4
The sensor outputs in the diagonal directions of the divided sensor 114 are added by adders 117 and 118, respectively.

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. 11 shows a tracking control signal At by such a method and a track crossing signal TRC which is a binary output thereof. 1 of the tracking control signal At
One pulse of a tracking traverse signal is output as a wave, and the relative movement distance between the light spot and the optical card can be measured by counting this signal TRC. 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. 12 is a block diagram showing a configuration of a conventional optical card recording / reproducing apparatus. 12, 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. MPU201
Controls the motor drive circuit (not shown) to drive the loading motor to introduce the optical card 107 into the apparatus and mount it on the carriage 202. In addition, MPU20
1 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. Thereafter, the MPU 201 connects the switch SW1 to the A side, gives a fixed command value to the D / A converter 221 and supplies a voltage signal corresponding to the command value to the AT actuator drive circuit 216. The command value at this time is the optical head 204
The drive current is set to a value that does not cause a drive current to flow through the actuator 125, 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. MPU
Reference numeral 201 performs focus pull-in using the focus control signal Af such that the light beam focuses 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,
A control value is calculated based on the obtained scanning speed and residual distance, and speed control of the DC motor 209 is performed. MPU201
Is supplied to the DC motor drive circuit 208 via the D / A converter 207, and moves the carriage 202 while controlling the speed.

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 the jump drive signal is supplied, the objective lens 106
Moves across the track, and at this time, the comparison circuit 2
13 outputs a track crossing signal and supplies it to the MPU 201. The MPU 201 counts the track crossing signal, and when reaching the target track, switches SW1 to the B side and turns on the tracking servo. At the same time, SW2
To the A side, and shift to the double tracking servo. Next, the optical head 204 is scanned to record / reproduce information on the target track.

Next, the speed control method will be described.
FIG. 13 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. 14 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, in a region where a track crossing signal cannot be obtained, the optical head and the optical card are relatively moved by driving at a constant voltage or a constant current. The speed at the time of entering the region greatly varies if there is a variation in the characteristics of the DC motor or the load of the mechanism, a change in the motor characteristics due to an environmental temperature or a change over time, or a change in the load of the mechanism. Therefore, if the moving speed is too high and the target track is close, 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. In some cases, it was not possible to pull tracking into the target track.

FIG. 15 is a diagram showing the relationship between the moving speed and the stopping distance. FIG. 15A shows the horizontal direction of the optical card,
The figure shows a part of the optical card when the vertical axis is taken in the longitudinal direction of the optical card. In FIG. 15B, the horizontal axis represents the distance X from the home position HP, and the vertical axis represents the moving speed. In FIG. 15A, tt1, tt2, tt3... Represent tracking tracks, and are shifted from the home position HP to tt.
No. 1 is an area without a track. Since open control is performed in an area where there is no track from the home position HP to the tracking track tt1, if there is a variation in the characteristics of the DC motor or the mechanical unit load, a change in motor characteristics due to environmental temperature or aging, or a change in mechanical unit load, The moving speed fluctuates greatly.

[0024] In this case, the moving speed is assumed to vary from V _x to V _n. When speed is minimum accelerating from X = 0, becomes V = V _n at X = X _na, after moving substantially at a constant speed, detecting a track crossing signal from tt1, tt
The speed is calculated between 1 and tt2, and the brake is applied at the maximum to stop at _Xn . Further, when the speed is maximum accelerating from X = 0, becomes V = V _x at X = X _xa, after moving substantially at a constant speed, detecting a track crossing signal from tt1, while tt1~tt2 in calculating the rate, it stops at X _x over maximum braking. However, since the no track area is open control, speed when entering the region of the track fluctuates between V _x ~V _n, the moving speed becomes maximum V _{x X} = _{X x} It was impossible to access a closer area, and it was difficult to access near tt1 in an area where detection of a track crossing signal was started.

The present invention has been made in view of the above-mentioned conventional problems, and provides an optical information recording / reproducing apparatus which can surely access a track near the first track of a recording area regardless of movement speed fluctuation. The purpose is to do.

[0026]

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. Controlling the relative movement speed of the optical head and the recording medium based on the target speed obtained, when the optical head accesses a target track from a home position, The optical head and the recording medium are moved relative to each other by the open control, and in the area where the track crossing signal is detected, the speed is switched to the speed control by the speed control means, and the optical head is moved to a predetermined track. This is achieved by an optical information recording / reproducing apparatus characterized by moving to a target track after moving.

[0027]

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, DC
The motor drive circuit 220 is a drive circuit that drives the DC motor 209 to move the carriage 202 on which the optical card 107 is mounted in the track orthogonal direction. When accessing the target track from the home position HP of the optical card 107, the DC motor drive circuit 220 changes from voltage drive, which is open control, to speed control drive by the command Q of the MPU 201 when the moving speed is detected based on the track crossing signal. Is switched to the current drive.

Here, in the present embodiment, the optical card 107
DC from open position from home position 107
When the motor 209 is driven and enters the recording area and the track crossing signal is output from the comparison circuit 213, the open control is switched to the speed control. Figure 1 shows the speed control method.
3, completely the same as the method of FIG. Also, at this time, the track to be accessed first is not the target track, and even if the speed is maximized due to the movement speed fluctuation during the open control, the speed control starts decelerating by detecting the track crossing signal and decelerates by tracking. The minimum track (a predetermined track closest to the first track) that can be normally pulled in is determined. Thereafter, speed control (or track jump) is performed from a predetermined track to access a target track.

Next, the track access operation 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, as in FIG. 15A. 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. The target track to be accessed X _t, the predetermined track to initially access the X _x. in this case,
It is an X _t <X _x. It is assumed that the optical head 204 is already located at the home position HP. First, when there is a track access command, the MPU 201 sets SW2 to B
And supplies a predetermined command value to the D / A converter 207 at the same time. The D / A converter 207 supplies a corresponding voltage signal to the DC motor drive circuit 220, and the DC motor 209 is driven at a constant voltage (or at a constant current).
By driving the DC motor 209, the carriage 202 moves from the home position HP (X = 0) of the optical card 107 in the track orthogonal direction by open control.

Here, it is assumed that the movement speed fluctuates during the open control, and fluctuates at the maximum speed V _x and at the minimum speed V _n . In this case the movement speed of the carriage 202 will be described as in which the maximum of V _x. When the carriage 202 moves in the direction orthogonal to the track and the light beam of the optical head 204 enters the recording area of the optical card 107, the comparison circuit 21
3, a track crossing signal is output between the tracking tracks tt1 and tt2. When the track crossing signal is output, the MPU 201 switches to the speed control, and executes the speed control process of FIG. 13 at regular intervals. At this time, even the first track moving speed variation to access the maximum as described above, tracking is determined to a predetermined track X _x that can be pulled correctly, the MPU 201 in FIG. 2 (b) As shown in FIG.
Speed control is performed so as to follow _x . When the light beam of the optical head 204 reaches a predetermined track X _x, M
The PU 201 pulls in the tracking by turning on the tracking servo.

The light beam of the optical head 204 in [0031] above is in a state of being drawn into the predetermined track X _x. Then, MPU
201 SW1 the A-side, switch the SW2 to the B side, performs speed control process in FIG 13 from a predetermined track X _x to the target track X _t, while following the target speed L _xt as shown in FIG. 2 (b) The carriage 202 is moved. Upon reaching the target track X _t, the MPU 201 may SW1 a B side,
Switch SW2 to the A side, and switch the light beam to the target track _Xt.
Draw in. Next, the MPU 201 operates the VCM drive circuit 21.
9, the optical head 204 is moved in the track direction by driving the voice coil motor. At this time,
After reading out the track number and confirming that the track is the target track, information is subsequently recorded on the target track or the recorded information is reproduced.

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. The switch SW4 is switched on and off by the switching signal Q.
The positive terminals of the power operational amplifiers 301 and 302 are supplied with a voltage that is の of the power supply voltage V. Here, the coil impedance of the DC motor 209 is Z, R1 to R6 have the same resistance value, and during open control, SW4 is opened by a switching signal from the MPU 201. At this time,
When a control signal from MPU201 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, by switching SW4, the DC motor 209 can be switched between voltage drive and current drive.

In the present embodiment, when a track is accessed from the home position, the track is first moved to a predetermined track and then moved from the predetermined track to a target track. In this case, even when the target track is close to the head track, the target track can be normally drawn into the target track. Incidentally, in the above embodiment has been described for the case of X _t <X _x, after the case of X _x <X _t likewise moved temporarily to a predetermined track X _x, is moved further away the target track X _t I just need.

Next, a second embodiment of the present invention will be described. In the first embodiment, the target track is moved to the target track once and then to the target track regardless of whether the target track is farther or closer than the predetermined track. However, in the second embodiment, the target track is moved more than the predetermined track. Is far from the target track. Second
Will be described with reference to FIG. First, MPU2
01 is a target track X when there is a track access command.
comparing _t with a predetermined track X _x, it determines whether the target track is far for a given track.

Here, if target track ≧ predetermined track, it is moved directly to the target track. FIG. 4 shows a case where the target track = the predetermined track. First,
The MPU 201 moves the carriage 202 in the track orthogonal direction by open control from the home position HP of the optical card, and switches to speed control when a track crossing signal is output between the tracking tracks tt1 and tt2,
The speed control process of FIG. 13 is executed at regular intervals. At this time, while following the target speed, such as mt corresponding to the target track X _t as shown in FIG. 4 (b) the carriage 202
To move. When the target track _Xt is reached, tracking is pulled into the target track to complete the track access. In the present embodiment, when the target track is farther than the predetermined track, the target track is directly moved to the target track, so that the access time can be reduced.

Next, a third embodiment of the present invention will be described. In the first and second embodiments, the predetermined track to be accessed first is determined in advance. In the third embodiment, the predetermined track to be moved first is changed according to the moving speed during the open control. In this case, the smallest track (the track closest to the head track) that can normally pull in the tracking corresponding to the moving speed is determined and stored in a table or the like. Alternatively, a predetermined track corresponding to the moving speed may be calculated from a relational expression obtained in advance.

FIG. 5 shows a speed profile in this case. X a predetermined track when the maximum moving speed V _x
x, and X _n a predetermined track when the minimum of the moving speed V _n, the target track as an X _t. However, FIG. 5 shows that X _t <X _n
<X _n is shown. If there is an access command, M
The PU 201 moves the carriage 202 in the track orthogonal direction from the home position HP by open control.
Next, when a track crossing signal is output between the tracking tracks tt1 and tt2, the MPU 201 calculates a moving speed from the track crossing signal, and determines a predetermined track corresponding to the moving speed by referring to the table.

[0039] For example, when the moving speed is to be had at V _x, it determines the predetermined track X _x corresponding thereto from the table. Then, the MPU 201 performs the speed control process in FIG. 13, while following the target velocity P _x carriage 202
Moving the draw tracking a predetermined track X _x. Thereafter, the speed control from the predetermined track X _x, while following the target speed P _xt as shown in FIG. 5 (b) by moving the carriage 202 reaches the target track X _t, draws tracking the target track Completes track access.

Further, when the moving speed during the open control is assumed to be V _n, it determines the predetermined track corresponding thereto by referring to the table to X _n. Then, the MPU 201 performs the speed control, the target speed P _nt as shown in FIG. 5 (b)
The carriage 202 is moved to a predetermined track _Xn while following the above, and tracking is performed. Next, the speed control from the predetermined track X _n, while following the target speed P _nt is moved to the target track X _t, completes the track access draws tracking the target track.

Next, the operation in the case of X _n <X _t <X _x will be described with reference to FIG. First, home position H
When the carriage 202 is moved by open control from P and a track crossing signal is output between the tracking tracks tt1 and tt2, the MPU 201 calculates the moving speed and determines a predetermined track corresponding to the moving speed by referring to the table. I do. For example, the moving speed of assuming that a V _x, determines the predetermined track corresponding to it X _x. Next, the speed control, while following the target velocity P _x as shown in FIG. 6 (b) is moved to a predetermined track X _x, draw tracking a predetermined track X _x. Thereafter, the speed control to the target track X _t while follow a predetermined track X _x the target speed P _xt, completes the track access draws tracking the target track X _t.

Further, a predetermined track is accordingly when the moving speed was V _n is a X _n, when the target track X _t is farther than the predetermined track moves directly to the target track X _t. That is, when X _n ≦ X _t , the target track is directly moved to shorten the access time. Therefore,
While following the target speed P _t by the speed control as shown in FIG. 6 (b) is moved to the target track X _t, completes the track access draws tracking the target track X _t. In the present embodiment, since the predetermined track to be moved first is changed according to the moving speed at the time of the open control, track access can be performed in a short time.

In the above embodiment, the carriage on which the optical card is mounted is moved in the direction perpendicular to the track, but the optical head may be moved in the direction perpendicular to the track.
Although a DC motor is used as a drive source for moving the carriage, a voice coil motor or the like may be used. Further, in the region where the track crossing signal can be obtained, the current driving is switched, but the voltage driving may be maintained.

When returning to the home position HP when the optical card is ejected or the like, the light beam irradiation is turned off and the movement in the cross-track direction is performed by voltage driving by open control. That is, since the light beam is turned off even 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.

[0045]

As described above, according to the present invention, when the track is accessed from the home position of the recording medium, the target track is accessed after the track is once moved to a predetermined track where the tracking can be reliably drawn. Therefore, regardless of the relative movement speed fluctuation at the time of the open control, even if the target track is close to the head track, the tracking can be reliably drawn into the target track. When the target track is farther than the predetermined track, the access time can be reduced by directly moving to the target track. Further, by changing the predetermined track to be accessed first according to the relative moving speed at the time of the open control, the access time can be similarly reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first 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 for explaining a track access operation according to a second embodiment of the present invention.

FIG. 5 is a diagram for explaining a track access operation according to a third embodiment of the present invention.

FIG. 6 is a diagram for explaining a track access operation according to a third embodiment of the present invention.

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

FIG. 8 is a diagram showing a relative scanning speed on a recording surface of an optical card and a recording area of the optical card.

FIG. 9 is a diagram showing a light spot on an optical card.

FIG. 10 is a circuit diagram showing an example of a signal processing circuit of a conventional optical card recording / reproducing device.

FIG. 11 is a diagram showing a tracking control signal and a track crossing signal when the optical head crosses a track.

FIG. 12 is a block diagram showing a conventional optical card recording / reproducing apparatus.

FIG. 13 is a flowchart showing speed control at the time of track access.

FIG. 14 is a diagram showing a speed profile at the time of track access.

FIG. 15 is a diagram for explaining a track access operation of the conventional device of FIG. 12;

[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 (4)

[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 a recording medium based on a target speed corresponding to a residual distance to a target track, wherein the optical head is moved from a home position to a target track. When the optical head is accessed, the optical head and the recording medium are moved relative to each other by controlling the moving means by open control. In the area where the track crossing signal is detected, the speed is switched to speed control by the speed control means,
An optical information recording / reproducing apparatus, wherein the optical head is moved to a target track after moving the optical head to a predetermined track. 2. The track according to claim 1, wherein the predetermined track is a track closest to a head track among tracks capable of reliably pulling in tracking when the speed at the time of the open control is maximum. An optical information recording / reproducing apparatus according to claim 1. 3. The optical information recording apparatus according to claim 1, further comprising means for comparing the target track with a predetermined track, and when the target track is farther than the predetermined track, the target track is directly moved to the target track. Playback device. 4. The system according to claim 1, wherein a relative moving speed at the time of the open control is calculated based on the track crossing signal, and a predetermined track to be moved first is changed according to the calculated moving speed. Optical information recording and reproducing apparatus.