JPH0689518A - Track jump signal generation circuit - Google Patents

Abstract

PURPOSE:To obtain a track jump signal generation circuit constituted so that adjustment is unnecessitated. CONSTITUTION:An acceleration/deceleration period of a track jump pulse TJP is decided by counting the rise or the fall of a tracking zero cross pulse TZC being a detection pulse relating to a laser for following a track by a counter 62. Thus, adjustment for adjusting the width of the tracking zero cross pulse TZC to cope with the dispersion of the mechanical parts, etc., of a motor 4 and a detection head is unnecessitated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a track jump signal generating circuit, and more specifically, a CD player or LD for reproducing a so-called DAD (digital audio disc).
The present invention relates to an improvement of a track jump signal generation circuit which is used for a player or the like and generates a track jump signal for controlling a so-called track jump that jumps across a recording track.

[0002]

2. Description of the Related Art FIG. 2 shows a so-called C compact disc.
The recording image of D is shown. Here, 7 is an image of a track on which acoustic signals and the like are recorded. Reference numeral 8 indicates a read position by the detection head, and reference numeral 9 indicates an example of the moving direction of the detection head. The track 7 has a spiral shape (although it is actually much denser than in the figure) like a recording groove formed on a conventional record board, and the track rotates as the CD rotates. During normal reproduction, the read head is controlled by the read position control mechanism so that the read position 8 stays on the track 7, and as the track 7 rotates, it moves at a rate of one track per one rotation.

In order to explain this control method in detail, FIG. 3 shows an enlarged view near the read position 8. The track 7 is composed of a series of recording units, such as elongated holes 7a, 7b, 7c, which have different light reflection states and lengths according to the recorded values. When reading the elongated hole 7b, which is also called a pit, the laser beam for recording and reading is at the position 8 on the elongated hole 7b.
It is performed by irradiating D and detecting its reflection state and the like. Then, as the CD rotates, the elongated holes 7c, 7b, 7a sequentially move to the position of the irradiation position 8D, and the recorded information is sequentially read.

Further, another pair of laser beams are used for track following. This track tracking laser light is
The positions 8E and 8F on both sides of the long hole 7b are irradiated, and the irradiation position 8 is adjusted so that the value of the difference signal of their reflection amounts becomes "0".
E, 8F are controlled. Therefore, when the irradiation positions 8E and 8F are at the target positions at both ends of the elongated hole 7b, the reflection amounts of these are balanced, and the irradiation position 8D is the irradiation position 8D.
Since it is located at the center of E and 8F, the detection head is controlled so that the irradiation position 8D, that is, the reading position 8 remains on the track 7.

The above description is for the control of the read position in the normal reproduction state. On the other hand, there are cases in which it is desired to perform fast-forwarding, cueing, etc. during or before this reproduction. At that time, the detection head corresponding to the read position 8 needs to move off the track 7 in the direction 9, for example, to jump across the recording track at a high speed and move to another read position. It is necessary to do so-called track jumps.

Then, a track jump signal is generated for controlling the track jump. This signal is
It is one of the control signals sent to the read position control mechanism, and is a signal indicating an acceleration period and a deceleration period for the interlaced movement. FIG. 4A shows a waveform example of the track jump signal TJP. The high level (“H”) portion of the first half portion indicates the acceleration period, and the low level (“L”) portion of the second half portion indicates the deceleration period. The detection head is
The vehicle moves in response to the track jump signal TJP and is accelerated in the first half to jump over at high speed, decelerated in the latter half to end the movement, and finally stays on the nearest track to the movement end position.

Further, in FIG. 4 (b), a corresponding detection pulse, so-called tracking zero cross pulse T, in which the difference signal of the reflection amount of the laser beam for track following is waveform-shaped,
An example of a ZC waveform is shown. Since the difference signal is controlled to be "0" during normal reproduction, the detection pulse TZC is not generated, but during a track jump, a detection pulse is generated every time the detection head crosses the track. In addition, the pulse width has a characteristic that it gradually decreases during the acceleration period and conversely increases during the deceleration period.

Therefore, in order to utilize this characteristic, the width of the detection pulse TZC is detected, and when the width (t1) becomes shorter than a predetermined width, the acceleration period is ended and the deceleration period is started, and the width (t2). ) Becomes longer than a predetermined width, it is determined that the vehicle has been sufficiently decelerated and the deceleration period is ended to generate a track jump signal. As a result, it is not necessary to add a special detection mechanism for the track jump, for example, another laser reading mechanism or the like, and the laser for tracking the track can be used also for the track jump.

[0009]

In such a conventional track jump signal generating circuit, in order to save a mechanism using an expensive and complicated laser or the like, a characteristic relating to the width of the detection pulse from the track following laser is changed. The track jump signal is generated by using this. However, the width of the detection pulse is
Since it is determined by the track crossing speed, it depends on the acceleration / deceleration characteristics of the scanning mechanism of the laser light. For this reason, the characteristics of the width of the detection pulse also fluctuate under the influence of the fluctuations of the mechanical characteristics of the scanning mechanism or the characteristics of the motor and its driver.

However, in the usage mode of a CD player or the like, the positioning accuracy at the time of a track jump is not so strict, and a deviation of several tracks from the target jump destination track is within an allowable range. Therefore, as long as the characteristic variation of the scanning mechanism or the like is within a predetermined range, it is sufficiently satisfactory. However, there are remarkable advances and diversifications in the technology of lasers and related parts, and a wide variety of things have been put to practical use. And, according to it, the above characteristics are distributed over a wide variety.

For this reason, since the characteristics of the width of the detection pulse greatly differ corresponding to each of these distributions, in order to absorb the difference and prevent malfunction, the time width (t1, t2) as the comparison reference is set. It became necessary to adjust the set value. However, such an adjustment work is a problem because it requires equipment and man-hours and deteriorates productivity. The purpose of this invention is
In order to solve the problems of the conventional technology,
The object is to realize a track jump signal generation circuit that does not require adjustment.

[0012]

The structure of the track jump signal generating circuit of the present invention which achieves the above object is as follows.
When performing the reading process of the recorded signal or data from the spiral track on which the signal or data is recorded,
When the detecting head for reading jumps across the track, a track jump signal indicating the acceleration period and the deceleration period of the jumping movement is generated to a mechanism for controlling the position of the detecting head. In the track jump signal generation circuit, a counter circuit receives a detection pulse detected each time the detection head crosses the track and counts a rising or falling edge of the detection pulse, and corresponds to half of the number of tracks to be skipped. Receiving a set value, comparing the count value of the counter circuit with the set value, detecting a match between them and outputting a match detection signal, and receiving a timing signal indicating the start timing of the interlaced movement. , Start the generation of the window pulse according to this timing signal,
And a window pulse generation circuit that ends the window pulse by receiving the coincidence detection signal twice, and the counter circuit resets the count value at a timing corresponding to both the timing signal and the coincidence detection signal. The period from the timing corresponding to the timing signal or the generation timing of the window pulse to the generation timing of the coincidence detection signal thereafter is the period of the acceleration of the track jump signal, and from the end timing of the acceleration period The period until the next generation timing of the coincidence detection signal or the end timing of the window pulse is the deceleration period of the track jump signal.

[0013]

In the track jump signal generating circuit of the present invention having such a structure, by counting the rising or falling timing of the detection pulse, the switching timing of the track jump signal is determined corresponding to the number of tracks to be skipped. . Unlike in the past, the width of the detection pulse is not used. Therefore, it is not affected by the variation of the characteristics related to the width of the detection pulse. Therefore, it is not affected by the change in the mechanical characteristics of the scanning mechanism or the change in the characteristics of the motor and its driver. Therefore, even if the characteristics of the laser of the detection head, which is the control target of this circuit, and its related parts are different, it is not necessary to make any adjustments to this.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A tracking circuit as an embodiment of the track jump signal generating circuit of the present invention will be described below with reference to the block diagram of FIG. Here, 1 is a reflected light E of a pair of laser lights for track following,
A differential amplifier that takes the difference between the detection signals of F and outputs the difference signal,
Reference numeral 2 is a servo filter for filtering the difference signal to generate a track following control signal, 3 is a driver for amplifying the control signal and outputting a drive current, and 4 is a motor driven by the drive current. Further, 5 is a waveform shaping circuit, and 60 is a track jump signal generating circuit.

Although not shown in the drawing, a scanning mechanism of a track following laser is attached to the motor 4, and the differential amplifier 1, the servo filter 2 driver 3, and the motor 4 both have a feedback loop. Form and perform servo function. Therefore, the read position control mechanism integrated with the scanning mechanism of the track following laser causes the detection head to follow the track so that the read position remains on the track. Regarding the operating principle,
Since it has been described in detail in the conventional example, the description will not be repeated.

However, the tracking servo function works when the connection between the servo filter 2 and the driver 3 is established by the switch SW in front of the driver 3. In the normal read state, this connection state is set, but in the case of a track jump, the switch SW
The connection between the servo filter 2 and the driver 3 is cut off by switching the connection of the driver, and the driver 3 receives the track jump pulse TJP (track jump signal), outputs a drive current corresponding to this, and forcibly drives the motor 4. Acceleration drive,
Further, deceleration driving is performed. As a result, the track jump is executed.

The track jump signal generating circuit 60 has a tracking zero cross pulse TZ in which the difference signal from the differential amplifier 1 is pulse-shaped by the waveform shaping circuit 5.
Upon receiving C (detection pulse), this track jump pulse TJP is generated. At this time, the track jump signal generation circuit 60 causes the tracking zero cross pulse TZC
In addition, a timing signal A indicating the start timing of the track jump, a set value B corresponding to half of the number of tracks to be jumped over, and a signal C indicating the moving direction of forward or backward are provided by an external controller or the like. Receive from.

The detailed structure will be described. 61 is an edge detection circuit for detecting the rising edge of the timing signal A, 62 is a counter for counting the rising or falling edges of the tracking zero cross pulse TZC, and 63 is a counter.
Is a match detection circuit that compares the count value of the counter 62 with the set value B and outputs a match detection signal when they match. The count value of the counter 62 is reset by both the rising timing of the timing signal A and the coincidence detection signal.

Further, 64 is a flip-flop which is reset at the rising edge of the timing signal A and is set by the coincidence detection signal to generate the original signal of the track jump pulse TJP, and 65 is an original signal of the track jump pulse TJP according to the direction signal C. A gate circuit which inverts or non-inverts the logical value of the signal, 66 is made conductive only during the track jump, and the original signal from the gate circuit 65 is supplied to the track jump pulse TJ.
A switch circuit for transmitting as P. And
Reference numerals 67 and 68 are flip-flops, and their constituent circuits are set at the rising edge of the timing signal A,
After that, it will be reset when receiving the match detection signal twice,
A window pulse for controlling the switch circuit 66 is generated. This pulse width indicates the track jump period.

Under such a configuration, the timing signal A
When the counter jump pulse T is received, the counter 62 is reset and the flip-flop 64 is reset.
The JP original signal becomes low level (“L”), the flip-flops 67 and 68 are set, and the window pulse becomes high level (“H”). The switch circuit 66 becomes conductive in response to this window pulse, and the signal C
Indicates, for example, inversion, a track jump pulse TJP having an inverted value of the original signal (“L”), that is, a high level (“H”) value is output. As a result, the motor 4 is forcibly accelerated to start the track jump.

Then, the tracking zero cross pulse TZC is generated every time the detection head crosses the track.
Then, when a half of the target number of tracks is traversed and the count value of the counter 62 reaches the set value B, a coincidence detection signal is generated. This means that the first half of the track jump is completed, the flip-flop 64 which receives the coincidence detection signal is set, and the value of the tracking zero cross pulse TZC is inverted and becomes the low level (“L”). As a result, the motor 4 is forcibly decelerated and the latter half of the track jump is started. The counter 62 is reset by the coincidence detection signal.

Further, each time the detection head crosses a track while decelerating, a tracking zero cross pulse TZ is generated.
C occurs. Then, when the count value of the counter 62 reaches the set value B again, that is, when the total number of target tracks is counted, a coincidence detection signal is generated. This means that the latter half of the track jump is also completed, and the window pulse becomes "L" in response to the second coincidence detection signal. As a result, the output of the track jump pulse TJP is stopped, and the motor 4, the detection head, etc. can return to the normal tracking operation.

As described above, since the track jump pulse TJP is generated from the tracking zero cross pulse TZC which is a detection pulse using the laser for tracking the track, a special detection mechanism for the track jump, for example, another laser reading. There is no need to add a mechanism or the like. Moreover, since the track jump pulse TJP is generated based on the count value obtained by counting the rising or falling of the tracking zero cross pulse TZC, it is affected by the width of the track jump pulse TJP having variations due to the reading position control mechanism or the like. There is no.

[0024]

As can be understood from the above description, in the track jump signal generation circuit of the present invention, even if the characteristics of the laser of the detection head, its scanning mechanism, the motor, its driver, etc. are different, There is no need to make any adjustments to the pulse width. As a result, there is an effect that productivity is improved.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a track jump signal generation circuit having the configuration of the present invention.

FIG. 2 is a schematic diagram of recording tracks on a CD.

FIG. 3 is a detailed view of a part thereof.

FIG. 4 is a waveform example of a track jump signal and a detection pulse.

[Explanation of symbols]

 1 differential amplifier 2 servo filter 3 driver 4 motor 5 waveform shaping circuit 7 track 8 read position 9 direction of movement 60 track jump signal generating circuit 61 edge detection circuit 62 counter 63 match detection circuit 64 flip-flop 65 gate circuit 66 switch circuit 67 , 68 flip-flops

Claims (1)

[Claims] 1. When performing a reading process of the recorded signal or data from a spiral track in which the signal or data is recorded, when a detection head for reading jumps across the track. In a track jump signal generation circuit that generates a track jump signal indicating an acceleration period and a deceleration period of the jumping movement with respect to a mechanism for controlling the position of the detection head, detection is performed each time the detection head crosses the track. Counter circuit that receives the detection pulse that is generated and counts the rising or falling edge of this detection pulse, and the set value that is half the number of tracks to be skipped,
A match detection circuit that compares the count value of the counter circuit with the set value, detects a match between them and outputs a match detection signal, and a timing signal that indicates the start timing of the interlaced movement A window pulse generation circuit that starts generation of a window pulse in response to the coincidence detection signal and then ends the window pulse by receiving the coincidence detection signal twice. Also, the count value is reset at the timing corresponding to, the period from the timing corresponding to the timing signal or the generation timing of the window pulse to the subsequent generation timing of the coincidence detection signal is the acceleration period of the track jump signal. From the end timing of the acceleration period, Track jump signal generation circuit period until end timing of the generation timing or the window pulses characterized in that it is with the deceleration period of the track jump signal of the serial coincidence detection signal.