JPH01130367A - Target signal retrieving device - Google Patents

Abstract

PURPOSE:To surely suppress oscillation of mobile optical parts and to quickly perform retrieval by supplying an acceleration signal after supplying a linear motor signal to a tracking coil driving circuit at the time of starting movement of an optical pickup device in the case of retrieval. CONSTITUTION:The linear motor signal generated from a first signal generating circuit is supplied to a tracking coil driving circuit 9 at the time of starting movement of an optical pickup device 1 in case of retrieval, and the acceleration signal generated from a second signal generating circuit is supplied thereafter. Consequently, oscillation of mobile optical parts is suppressed from the start to the end of movement of the optical pickup device 1. Especially, mobile optical parts are prevented from being not accurately controlled by the influence of problems on the structure such as play at the time of starting movement of the optical pickup device 1 or a problem of resolution of a movement extent detecting means in a low-speed movement area of the optical pickup device 1. Thus, oscillation of mobile optical parts for tracking control is sufficiently suppressed.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention performs a rough search by moving the entire optical pickup device at high speed in the tracking direction of a signal recording medium, and also tracks movable optical parts of the optical pickup device. Regarding a target signal search device that searches for a target signal track by performing a fine search by displacing the target signal in the direction,
In particular, the present invention relates to a target signal search device that suppresses vibrations when the movable optical component searches for a signal track.

(B) Conventional Technology Optical reproducing devices, such as CD players and laser vision players, are known that optically reproduce signals that have been completely recorded on a signal recording medium using an optical pickup device. As is well known, in the optical reproducing apparatus, in addition to main data signals such as music information and video information, a sub data signal of position index information representing the position of the disc is recorded. Specifically, CD
In the case of , index information called TOC (for music CDs, the starting position of famous songs, total number of strokes, total playing time, etc.) is recorded in the lead-in area, and 1775
A sub-data signal called a sub-coding signal that can complete one block in a second cycle is recorded, and the sub-coding signal consists of eight P-W channels. The position index information indicating the beginning of the song is displayed on the Q channel, the absolute elapsed time from the start point of the signal track, the elapsed time of famous songs,
Position index information indicating the song number and index is recorded. Therefore, the optical playback device is usually equipped with a target signal search device so that the position index information can be used to search for a data signal such as the beginning of a target song manually specified. In addition, in the case of CD-ROM, the main data signal includes position index information, so
In a CD-ROM drive device, the position index information can also be used in the search to make the search more accurate.

By the way, as a target signal search device for an optical reproducing device,
A moving distance detecting means for detecting a moving distance of the optical pickup device is provided, and position data corresponding to the current position of the optical pickup device is created based on a distance signal obtained by the moving distance detecting means and is recorded on a CD. Create target data corresponding to the position of the target signal track to be searched based on the position index information, calculate the difference between the position data and the target data, calculate the distance from the difference, and calculate the distance. In some cases, the optical pickup device is moved based on the distance signal from the moving distance detecting means to perform a rough search.As is well known, the optical reproducing device uses the light generated from the optical pickup device. Focusing control to control the light beam in the optical axis direction, so-called focusing direction, in order to accurately focus the beam on the signal surface on the disk, and focusing control to control the light beam in the radial direction of the disk to make it follow the signal track on the signal surface. , tracking control is performed in the so-called tracking direction, and focusing control and tracking control are usually performed by displacing the objective lens.
The objective lens is displaceably supported. Therefore, after the playback position of the optical pickup device approaches the target signal track through coarse search, the target signal search device performs a fine search by displacing the objective lens to move the playback position onto the target signal track. It is being moved to .

As described above, the target signal search device equipped with the moving distance detecting means moves the irradiation point (reproduction position) of the light beam generated from the optical pickup device to the target signal track by one high-speed feed of the optical pickup device. Since it can be brought closer, it is advantageous for speeding up the search operation. Here, as the moving distance detecting means of the target signal search device, there are two methods: one detects the moving distance by counting the track cross signal generated when the light beam from the optical pickup device crosses the signal track; There is a method that uses an encoder or potentiometer that generates an output as the device moves, and uses the output from the encoder or potentiometer to detect the distance traveled.
In the former method, if the frequency of the track cross signal becomes too high, it will not be possible to count due to the detection circuit.
The moving speed of the optical pickup device cannot be made very high. Therefore, in order to shorten the search time, the latter method is preferable.

By the way, the target signal search device performs tracking control by the acceleration when the search operation is performed and the optical pickup device is displaced in the tracking direction, or by the inertia when the optical pickup device is stopped. Since the movable optical component vibrates, the vibration of the movable optical component causes the subsequent tracking control to take a long time and causes inaccurate search positioning of the target track. In particular, there has been an increase in the number of optical pickup devices that use linear motors to displace optical pickup devices at high speed in order to shorten search time.
Vibration of the moving optical components has become even more problematic.

(c) Problems to be solved by the invention In order to solve the above-mentioned problems, for example,
As shown in Publication No. 5278, we focused on the fact that the drive current supplied to the linear motor for driving the optical pickup device is approximately proportional to the acceleration of the optical pickup device,
A movable optical component (objective lens) for tracking control of a signal proportional to the drive current supplied to the linear motor.
A target signal search device configured to supply a target signal is known.

However, in reality, the drive current of the linear motor is not necessarily proportional to the acceleration of the optical pickup device due to factors such as friction in the drive mechanism of the optical pickup device or external forces such as inclination of the drive mechanism. Therefore, in the end, it was not possible to sufficiently suppress vibrations of the movable optical components for tracking control.

(d) Means for Solving the Problems The present invention has been made in view of the above points, and includes a linear motor for driving an optical pickup device in the tracking direction, and a driving current supplied to the linear motor. a linear motor drive circuit; a tracking coil drive circuit that supplies a drive current to a tracking coil for driving the movable optical components of the optical pickup device in the tracking direction; a first signal generating circuit that generates a signal, a moving distance detecting means for detecting a moving distance of the optical pickup device, and a distance signal obtained by the moving distance detecting means into an acceleration signal corresponding to a moving acceleration of the optical pickup device. a second signal generation circuit for converting, and a switch circuit that selectively supplies the linear motor signal from the first signal generation circuit and the acceleration signal from the second signal generation circuit to the tracking coil drive circuit; and supplying a linear motor signal to the tracking coil drive circuit for a predetermined period when the light distribution pickup device starts moving during the search,
Thereafter, the switch circuit is switched to supply an acceleration signal.

(*) Effect The present invention is designed to prevent optical pickups during searches due to structural problems such as rattling in the drive mechanism that drives the optical pickup device, or problems with the resolution of the moving distance detection means in the low-speed range of movement of the optical pickup device. During a predetermined period when the device starts moving, a linear motor signal is generated from the first signal generation circuit, and after the movement of the optical pickup device is stabilized, an acceleration signal is generated from the second signal generation circuit. Focusing on the fact that it approximates the actual acceleration of the optical pickup device, the linear motor signal is supplied to the tracking fill drive circuit for a predetermined period when the optical pickup device starts moving during a search, and then the acceleration signal is It was designed to be supplied.

(v) Embodiment Figure 1 is a circuit diagram showing an embodiment of the present invention. (1) shows a semiconductor laser (2) serving as a light source, and a half mirror for splitting the optical path and generating astigmatism. -(3) and
an objective lens (5) supported movably in the tracking direction and the focusing direction of the signal recording medium (4);
An optical pickup device (7) is provided with a photodetector (6) having a detection element for detecting a tracking deviation of the light beam toward the signal track, and is supported so as to be displaceable in the tracking direction of the signal recording medium (4). a tracking error detection circuit that uses the output signal from the photodetector (6) to indicate a tracking error of the light beam of the optical pickup device (1) to the signal track;
8) is a phase compensation circuit that compensates the phase of the output signal from the tracking error detection circuit (7) according to the drive system in the tracking direction of the objective lens (5) of the optical pickup device (1); A tracking coil drive circuit that supplies a drive current to a tracking coil (10) for driving the objective lens (5) in the tracking direction, and (11) a linear motor for driving the optical pickup device (1) in the tracking direction. , (婬) are a main scale (13) that is fixed to the optical pickup device (1) and is displaced in accordance with the movement of the optical pickup device (1), and a detection section that detects the movement of the main scale (13). A linear encoder consisting of (14), (15〉) is the linear encoder (
The encoded output signal from B) is decoded and converted into a waveform-shaped and multiplied pulse signal, and the output signal supplied from the linear encoder is used to direct the optical pickup device (1) in the traveling direction. According to the positive output end (
16a) and (17a), or the negative output end (16b
) and a decoder that outputs pulse signals from (17b);
(18) is an optical pickup device (
1) is a position data creation circuit that creates position data according to the current position; (22) is a target data setting circuit that sets index information according to the search target specified by (23), and (23) is set by the position data created by the position data creation circuit (18) and the target data setting circuit (20). (24) a target position calculation circuit that detects a difference with the target data and calculates the distance from the current position of the optical pickup device (1) to the target position, which is the position of the target signal track, based on the difference; The count value is set according to the numerical value calculated by the target position calculation circuit (23), and is counted down according to the pulse signal output from the positive output terminal (16a) of the decoder (15), (15) A counter that counts up in response to a pulse signal output from the negative output terminal (16b), (
(25) is a speed reference signal generation circuit that generates a speed reference signal serving as a reference for the speed at which the optical pickup device (1) is moved in accordance with the count value of the counter (24);
) consists of an F-V converter that converts a frequency signal into a voltage signal, and the number of pulse signals output per unit time from the positive and negative output terminals (17a) and (17b) of the decoder (15). Optical pickup device based on (1)
(27) is a speed signal generation circuit that generates a speed signal whose voltage value changes according to the moving speed of the speed signal generation circuit (27).
26) and differentiates the speed signal from the optical pickup device (
1) a differential circuit that converts into an acceleration signal according to the acceleration;
(28) is a subtraction circuit that subtracts the speed reference signal output from the speed reference signal generation circuit (25) and the speed signal output from the speed signal generation circuit (26>); (29)
is a phase compensation circuit that compensates the phase of the output signal from the subtraction circuit (28) according to the drive system of the optical pickup device (1), and (30) is a linear compensation circuit that compensates the output signal from the phase compensation circuit (29). A linear motor drive circuit (31) supplies a drive current to the motor (11).
) for generating a voltage according to the drive current supplied to the linear motor (11), and (32) a linear motor signal according to the drive current supplied to the linear motor (11) from the potential difference between both ends of the resistor (31). A first linear motor signal generating circuit (33) selectively supplies the linear motor signal from the linear motor signal generating circuit (32) and the acceleration signal from the differentiating circuit (27) to the next stage. switch circuit,
(34) is a second switch circuit that selectively supplies the signal from the first switch circuit (33) and the signal from the phase compensation circuit (8) to the tracking coil drive circuit (9);
35) are the first and second switch circuits (33) and (
34).

Here, a position data creation circuit (18), a target data setting circuit (20), a RAM (21), a target position calculation circuit (2
3), the speed reference signal generation circuit (25) and the switch switching circuit (35) are configured by a microcomputer,
The switch switching circuit (35) is connected to the target position calculation circuit (
From the time when it is detected that the optical pickup device (1) needs to be moved based on the distance to the target position calculated in step 23), the counter (24) performs an initial predetermined number of counts (for example, 2 counts). The first switch circuit (33) is switched to the a side until then, and then switched to the b side, and the count value of the counter (24) becomes "O" from the time when the search operation is performed by the input means (22).
The second switch circuit (34) is switched to the b side until the time is reached, and a switching signal is generated to switch the second switch circuit (34) to the a side at other times. - Furthermore, the linear encoder (super) and decoder (15) serve as moving distance detection means for detecting the moving distance of the optical pickup device (1), and as the linear encoder (super), an optical type is used. As shown in FIG. 2, the main scale (13) has a plurality of slits (36) arranged at equal intervals, and the detection section (14) has slits (36) arranged facing each other with the main scale (13) in between. The luminescent element, +(
37) and light receiving elements (38) and (39) are provided. In front of the light receiving elements (38) and (39), slits (
Auxiliary scales (40〉 and (41
) is provided. Therefore, the optical pickup device (1
) is completely moved and the main scale (13) is displaced, the amount of light detected by the light receiving elements (38) and (39) changes, and the light receiving elements (38) and (39> each have a 90' phase. Different output signals can be extracted.

In the apparatus configured as described above, when searching for a predetermined data signal, the input means (22) performs a search operation according to the target data signal. Then, the target data setting circuit (20) selects an index corresponding to the search target from among the index information of the signal recording medium (4) stored in the RAM (21) in advance in response to the operation of the input means (22). Information target data is set. On the other hand, the position data creation circuit (18) controls the optical pickup device (1) based on the position index information currently being reproduced supplied from the input terminal (19).
Position data is created according to the current position of. For that reason,
The target position calculation circuit (23) calculates the distance from the current position of the optical pickup device (1) to the target position, and the count value of the counter (24) is set according to the calculated value, so that the speed Reference signal generation circuit (25
), a speed reference signal can be generated according to the count value. The speed reference signal generated from the speed reference signal generation circuit (25) is passed through a subtraction circuit (28) and a phase compensation circuit (
29) to the linear motor drive circuit (30), so that the linear motor drive circuit (30) generates a drive type flow according to the speed reference signal. For that reason,
The linear motor (11) is driven according to the speed reference signal, and the optical pickup device (1) is moved accordingly. The count value set in the counter (24) is set to a positive or negative value depending on the direction of the target position relative to the current position, and the speed reference signal generation circuit (25) ) generate speed reference signals of different polarity.

When the optical pickup device (1) moves, the main scale (13) of the linear encoder (tsubo) moves, so the detection part (14) of the linear encoder (tsubo)
An output signal is generated from. The output signal generated from the detection section (14>) is decoded by a decoder (15).Here, the output signal generated from the detection section (14) is output from the two light receiving elements (38) and (39). A signal is output, and the output signals generated from the light receiving elements (38) and (39) have a phase difference of 90 degrees, so the decoder (15) detects the output signal whose phase is leading, thereby detecting the optical pickup. Determine the moving direction of the device (1),
When the playback position by the optical pickup device (1) is moving in the forward direction, the positive output ends (16a) and (17
If a pulse signal is generated from g> and the playback position by the optical pickup device (1) is moving in the returning direction,
Pulse signals are generated from the negative output terminals (16b) and (17b). Note that one pulse is generated per pitch of the main scale (13) from the positive and negative output terminals (16a) and (16b) connected to the counter (24).
Two light receiving elements (
By combining the output signals generated from 38) and 39, the resolution is increased so that 4 pulses can be generated per pitch of the main scale (13).

The decoder (1) moves according to the movement of the optical pickup device e (1).
5) positive or negative output end (16a) or (16
When a pulse signal is output from b>, the counter (24)
The karantoi nao is counted down or counted up one count at a time, approaching 'OJ. The speed reference signal generated from the speed reference signal generation circuit (25) changes sequentially according to the count value, and as the count value approaches r□ from a predetermined value, the moving speed of the optical pickup device (1) becomes slower. It changes as it becomes. Then, when the optical pickup device (1) reaches the target position, the count value becomes "0" and the speed reference signal generation circuit (25) stops generating the speed reference signal. , the movement of the optical pickup device (1) is stopped. At this time, since the reproduction position of the optical pickup device (1) has been displaced within the range where it can be moved to the target signal track by track jumping by the objective lens (5), the optical pickup device (1) then drives the objective lens (5). A search for the target signal track is thereby performed.

On the other hand, when a pulse signal is output from the positive or negative output terminal (17a) or (17b) of the decoder (15) in response to the movement of the optical pickup device (1), the pulse signal is output per unit time. The speed signal generation circuit (26) generates a speed signal corresponding to the moving speed of the optical pickup device (1). This speed signal is input to the inverting input terminal of the subtraction circuit (28) in phase with the speed reference signal generated from the speed reference signal generation circuit (25), so that the moving speed of the optical pickup device (1) can be adjusted. It acts as a negative feedback signal, and when the optical pickup device (1) at the time of search is moved by the linear motor (11), the second switch circuit (34) is activated by the switching signal from the switch switching circuit (35>). switch to the side,
The output signal from the first switch circuit (33) is supplied to the tracking fill drive circuit (9). The first switch circuit (33) includes a counter (24)
The tracking filter is switched to side A by the switch switching circuit (35) until the first predetermined number of counts is performed at the counter (24), and then switched to side B after the counter (24) counts that number. Drive circuit〈9
) includes the optical pickup device (1) at the time of search.
The linear motor signal generation circuit (
A linear motor signal generated from the differential circuit (27) is supplied, and after the predetermined period has elapsed, an acceleration signal generated from the differentiating circuit (27) is supplied. Here, the moving period of the optical pickup device (1) is shown as shown in FIG. 3 (a), and the actual moving speed of the optical pickup device (1) is shown in FIG. 3 (b).
, the actual acceleration of the optical pickup device (1) is as shown in FIG. 3 (c). On the other hand, since the linear motor signal generation circuit (32) outputs a linear motor signal according to the drive current supplied to the linear motor (11) from the potential difference between both ends of the resistor (31), this linear motor signal is It will look like Figure 3 (d). - On the other hand, since the speed signal generating circuit (26) generates a speed signal as shown in Fig. 3 (*), the differentiating circuit (26) differentiates this speed signal.
7) generates an acceleration signal as shown in FIG. Here, the speed signal generated from the speed signal generation circuit (26) may be caused by structural problems such as play due to the difference between the fulcrum and the point of action of the drive mechanism (not shown) of the optical pickup device (1). Or, due to poor resolution in the low speed range due to the influence of the pitch interval of the slits (36) of the main scale (13) (detection of minute displacements due to resolution), the difference between the actual speed and the actual speed when the optical pickup device (1) starts moving is caused by poor resolution in the low speed range. The error that occurs between the two becomes noticeable. Therefore, as a matter of course, a large error occurs between the acceleration signal generated from the differentiation circuit (27) and the actual acceleration when the optical pickup device (1) starts moving.

However, as the moving speed of the optical pickup device (1) increases, the influence of the structure of the drive mechanism of the optical pickup device (1) or the pitch interval of the slits (36) of the main scale (13) increases. The influence becomes negligible, and the decoder (15) is connected to the linear encoder (
Since a signal corresponding to the actual moving speed of the optical pickup device (1) obtained from the optical pickup device (1) is generated, the speed signal generated from the speed signal generating circuit (26) is approximately equal to the actual speed. Furthermore, when the optical pickup device (1) stops moving, the slit (
36) is affected by the pitch interval, but at the start of movement, it is not easily affected by the structure of the drive mechanism of the optical pickup device (1), so the acceleration signal generated from the differentiating circuit (27) and the actual acceleration are The error with this does not become large at the start of movement.

As a result, when the linear motor signal from the linear motor signal generation circuit (32) and the acceleration signal from the differential circuit (27) are compared with the actual speed, it is found that when the optical pickup device (1) starts moving, When the movement of the optical pickup device (1) is stable, the acceleration signal of the linear motor signal becomes approximately equal to the actual acceleration.

Therefore, the first switch circuit (33) is
As shown in the figure, by switching to the a side and then switching to the back side for a predetermined period at the start of the movement of the optical pickup device (1), the tracking coil drive circuit (9) receives approximately the actual acceleration of the optical pickup device (1). Equal signals will be provided. Therefore, the optical pickup device (
During the movement of the optical pickup device (1), the objective lens (5) is controlled by a signal substantially equal to the actual acceleration of the optical pickup device (1) as shown in FIG. 3 (H), thereby suppressing vibration.

In addition, in Figures 3 (a) to (h), the horizontal axis is time (1).
3 (B), (C), (D), (E), (
In (f) and (h), the vertical axis represents voltage.

When the movement of the optical pickup device (1) is completed, the switch changeover circuit (35) switches the second switch circuit (34).
is immediately switched to side a. Therefore, a tracking error signal corresponding to the tracking error from the tracking error detection circuit (7) is supplied to the tracking coil drive circuit (9) via the phase compensation circuit (8), so that tracking control can be performed immediately. A pulling operation is performed,
Thereafter, the objective lens (5
), and the search for the target signal track is accomplished.

In the above-described embodiment, the first switch circuit (33) is switched to the a side only for a predetermined period when the optical pickup device (1) starts moving, where the acceleration signal from the differentiator circuit (27) differs greatly from the actual acceleration. Although the acceleration signal from the differentiating circuit (27) is better than when the optical pickup device <1) starts moving and is less affected by the vibration of the objective lens (5), the acceleration signal from the differentiating circuit (27) is Further effects can be expected if the first switch circuit (33) is switched to the a side for a predetermined period of time until the optical pickup device (1) stops moving, which differs from the acceleration.

Further, in the embodiment, the target data setting circuit (20)
Index information is stored in advance in RAM (21) in order to set target data according to the index target.
In the case of a D-ROM with a large capacity of index information, the index information is stored in a RAM in the microcomputer.
Since the index information cannot be stored on the CD
- The target data may be stored in a host computer connected to the ROM drive, or the index information of the CD-ROM may be read each time a search is made and the target data setting circuit (2o) may set the target data.

(G) Effects of the Invention As described above, the target signal search device according to the present invention generates a signal from the first signal generation circuit to the tracking coil drive circuit for a predetermined period at the start of movement of the optical pickup device during search. Since the linear motor signal is supplied and then the acceleration signal generated from the second signal generation circuit is supplied, it is possible to suppress the vibration of the movable optical components from the start of movement of the optical pickup device to the end of movement. In particular, it is difficult to control the movable optical parts accurately due to structural problems such as rattling at the start of movement of the optical pickup device, or problems with the resolution of the moving distance detection means in the low-speed range of movement of the optical pickup device. Since vibrations of the movable optical component are prevented from occurring, vibrations of the movable optical component can be reliably suppressed, and there is an advantage that the speed of the search can be increased.

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram showing one embodiment of the present invention, and FIG.
The figure is a model diagram showing a linear enhancer, and Figures 3 (a), (b), (a), (d), (ne), (f), (g), and (h) are waveform diagrams for explaining the present invention. be. Explanation of main drawing numbers (1)... Optical pickup device, (10)... Tracking filter, (7)... Tracking coil drive circuit, (11)... Linear motor, (12)...
・Linear encoder, (15)...decoder, (
18)...Position data creation circuit, (20)...Target data setting circuit, (23>...Target position calculation circuit, (24)...Counter, (25)...Speed reference signal generation circuit, (26)... speed signal generation circuit,
(27)...Differential circuit, (28)...Subtraction circuit, (30)...Linear motor drive circuit, (32>...
...Linear motor signal generation circuit, (33)...1st
Switch circuit, (34)...Second switch circuit, (3
5)...Switch changeover circuit.

Claims (1)

[Claims] (1) Equipped with an optical pickup device that optically reproduces a signal recorded on a signal recording medium and has a movable optical component that is supported so as to be displaceable in order to follow the signal track of the signal recording medium, and to generate a target signal. A target signal search device that performs a coarse search by moving the optical pickup device at high speed in the tracking direction of a signal recording medium when searching for a track, and also performs a fine search by displacing the movable optical component in the tracking direction, A linear motor for driving the optical pickup device in the tracking direction, a linear motor drive circuit for supplying a drive current to the linear motor, and a drive current for supplying a tracking coil for driving the movable optical component in the tracking direction. a tracking coil drive circuit for detecting the movement of the optical pickup device; a first signal generation circuit for generating a linear motor signal corresponding to a drive current for driving the linear motor; a second signal generating circuit that converts a distance signal obtained by the distance detecting means into an acceleration signal corresponding to the moving acceleration of the optical pickup device; a linear motor signal from the first signal generating circuit; and a linear motor signal from the first signal generating circuit and the second signal. a switch circuit that selectively supplies an acceleration signal from a generation circuit to the tracking coil drive circuit, and supplies a linear motor signal to the tracking coil drive circuit for a predetermined period when the optical pickup device starts moving during a search. A target signal search device characterized in that the switch circuit is switched to supply the acceleration signal and then supply the acceleration signal.