JPS6066372A - Tracking control circuit - Google Patents

Abstract

PURPOSE:To attain precise tracking control by fixing a relative speed of an information detecting point to a recording track at the time of jumping operation by using a voltage source and a reference. CONSTITUTION:A monostable multivibrator 12 is triggered by a tracking error signal shaped at its waveform and voltage proportional to the relative speed is outputted from an LPF13. When a jump instruction is inputted, the output Q of an FF8 is turned to the H level, a loop switch 3 is turned off and a tracking loop is opened. Simultaneously, the input of the monostable multivibrator 12 is turned to the H level and a relative speed signal is outputted from the LPF13. The relative speed signal and the output of the voltage source 19 are transmitted through a subtractor 14, a polarity inverting circuit 15 and a switch 20 to form a speed servo loop for driving a mirror 7. Namely, spot light P1-P3 move at a relative speed proportional to the voltage set up by the voltage source 19. Since the relative speed is fixed by using the voltage source as a reference, precise tracking jump control is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tracking control circuit having a function of jump-controlling a track at a recorded information detection point in a recording/reproducing apparatus.

In the recorded information reproducing apparatus, the recording information detection point is set from the recording track currently being traced to another target record i~
A so-called jump operation may be performed to force the player to jump to the rack.

Conventionally, this operation was performed as follows. That is, as shown in FIG. 1, when the relative speed of the information detection point with respect to the recording track exceeds a predetermined speed, a brake pulse is issued to decelerate the information.

Therefore, the relative speed was changing up and down around a predetermined relative speed. This makes it difficult to jump only the correct number of tracks. For example, if the tracking servo lube is closed at time t1 in Fig. 1, the speed is smaller than the predetermined value, so it locks in before the target 1~lack, and if it is 12 o'clock, the speed is lower than the predetermined value. Since it is larger than the value, it has the disadvantage of locking in beyond the target track.

The present invention provides a tracking control circuit that can perform accurate i~rack jump control by keeping the relative movement speed of the information detection point to the record 1~rack constant during a jump operation.
The purpose is to provide.

Therefore, the racking control circuit according to the present invention includes a position detection means for detecting the relative position of the information detection point with respect to the recording track, a detection means for frequency detecting the output of the position detection means, and a racking control circuit according to the number of skipped tracks. a counting means for generating an output, a comparing means for detecting a difference between the counting means and the target track, a reference signal means controlled by the output of the comparing means, and an output of the reference signal means and the detecting means. The information detection point is configured to be moved based on the output of the addition means.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 2, three spot lights P1 to P3 are obtained by converging a laser beam on records 1 to rack T.
are irradiated with the positional relationship shown. That is,
When the information detection spot light P2 is on the recording track T, the other two spot lights P1 and P3 are located on both side edges of the recording track T. Therefore, when the detection spot light P2 shifts in the direction perpendicular to the track (the radial direction of the recording disk), the difference in the amount of reflected light of both the spot lights P1 and P3 corresponds to the direction and magnitude of the shift. Each of the reflected lights of the two spot lights P1 and P3 is converted into an electric signal by photoelectric conversion elements 1a and 1b. Each output of these photoelectric conversion elements 1a and 1b is supplied to a differential amplifier 2. This differential amplifier 2J: photoelectric conversion element 1a
A signal corresponding to the level difference between the outputs of the spot lights P1 and P3, that is, a signal corresponding to the difference in the amount of reflected light of the spot lights P1 and P3 is output. The output of the differential amplifier 2 is supplied as a tracking error signal to the equalizer amplifier 4 via the loop switch 3, and phase compensation is performed.

The output of this equalizer amplifier 4 passes through an adder 5 and becomes an input to a drive amplifier 6. The output of the drive amplifier 6 drives the drive coil of the tracking mirror 7, which shifts the spot lights P1 to P3 in a direction perpendicular to the recording track T, so that the information detection spots 1 to P2 accurately track the recording track. controlled like this. In addition, loop switch 3
is configured to be in an open state when a low level signal is supplied to the control input terminal.

A tracking mebo loop is formed by the above-described portion. Further, the DC portion of the output of the drive amplifier 6 is extracted by a low-pass filter (not shown), etc., and then supplied to a slider motor drive circuit (not shown) for moving the tracking mirror 7 in a direction perpendicular to the track. .

On the other hand, the tracking error signal is input to the waveform shaper 9, and from this output passes through the inverter 10 and enters one input of the switch 11, and the other input is directly connected to the waveform shaper 9.
output is supplied.

This switch 11 is selected by an F/R signal that determines the direction of skipping, and the output of the switch 11 is connected to the input of a mono multivibrator 12.

The output of the mono-multivibrator 12 passes through a low-pass filter 13 and is connected to the ten input of a subtracter 14. or,
The output of the mono multivibrator 12 is fed into the clock input of the counter 16. Counter 16 is a programmable down counter.

The output of the subtracter 14 is connected to the output of a variable voltage source 19, whose voltage is controlled by the output of the counter 16 and the output of an 8-track detector 18 which performs rack detection. The jump instruction is input to the set input of the flip-flop 8, and the output of the zero detector 17, which detects zero detection from the output of the counter 16, is connected to the reset input.

The output of flip 70 tube 8 is mono multivibrator 1
2 CLR input, switch 20. Furthermore, it is reversed and controls loop switch 3.

The output of the subtracter 14 passes through a polarity inverter 15 and a switch 20 to drive the tracking mirror 7 from the adder 5.

Next, the operation of the present invention will be explained with reference to FIG.

The mono-multivibrator 12 is triggered by the waveform-shaped signal of the tracking error signal and generates a signal with a constant pulse width. This output is passed through the low-pass filter 13
The voltage is proportional to the frequency of the tracking error signal. That is, the output of the low-pass filter 13 is obtained by frequency-detecting I to racking error numbers. The frequency of the tracking error signal is the spotlight P1 to P3.
Since 1 is proportional to the relative speed of the rack, the output of the low-pass filter 13 is a voltage proportional to the relative speed.

, 1001-rack jump is explained as an example. First, the counter 16 is set to 100. When a jump command is received, the output Q of the flip-flop 8 becomes 1-1i0h level, the loop switch 3 is turned off, and the tracking loop is opened. At the same time, the CLR input of the mono multivibrator 12 becomes High, so a relative velocity signal is output from the low-pass filter 13. This signal and the output of the voltage source 19 pass through the subtracter 14, the polarity inversion circuit 15, the switch 20 (closed), and the mirror 7.
A speed servo loop is formed to drive the . That is, the spotlights P1 to P3 move at a relative speed proportional to the voltage set by the voltage source 19. Therefore, it moves at a constant speed V1 without being affected by the magnitude of eccentricity or the sensitivity of the mirror.

Since the output of the mono multivibrator 12 is input to the clock Ck of the counter 16, the counter 16
The output is counted down each time it passes one track. When the countdown is repeated and the output of the counter 16 shows 8 after jumping 92 tracks, it is 8i.
- The rack detector 18 is activated to switch the voltage source 19 to reduce the voltage. As a result, the relative speed between the spotlights P1 to P3 and the track becomes constant at a speed V2 lower than the initial speed.

Furthermore, when the spot light P2 comes onto the target i-rack, the output of the counter 16 becomes O, and the output of the zero detector 17 resets the flip-flop 8. This causes the switch 20 to become an oven, stopping the speed servo and closing the loop switch 3, thereby locking in at the objective 1-rack.

The polarity reversing circuit 15 and switch 11 are switched in the jump direction and are used to perform forward and reverse jumps.

In the above embodiment, the speed is changed by detecting that the track is 8 tracks ahead of the target track;
It works even if it is not easy. In addition, the voltage source 19 is 2
Although the steps are changed, smooth speed control may be performed by performing more steps of switching, such as remaining 16 tracks, 8 tracks, and 4 tracks, for example.

As described above, according to the present invention, the relative speed of the information detection point with respect to the recording track during the jump operation is kept constant by setting the voltage source to 1J, which is accurate to 1-rough-1. - Engine control becomes possible.

[Brief explanation of drawings]

FIG. 1 is a waveform diagram for explaining the conventional example, FIG. 2 is a circuit block diagram showing an embodiment of the present invention, and FIG. 3 is a waveform diagram for explaining the operation of the embodiment of the present invention. In the symbols used in the drawings, 1a, 1b...Photoelectric conversion element 12...Mono multivibrator 14...
...Subtractor 16...Counter 18...8 Track detector 19...Voltage source. Patent applicant: Pioneer Co., Ltd.

Claims (1)

[Claims] Multiple records arranged in parallel 1 to 1 at the back of the rack
Information detection points existing in one recording track can be controlled to jump to another target I-rack.
The lagging control circuit includes a position detecting means for detecting the relative position of the information detection point with respect to the recording track, a detecting means for frequency detecting the output of the position detecting means, and a lagging control circuit that detects the relative position of the information detection point with respect to the recording track. ]; a comparison means for detecting the difference between the counting means and the target rack; a reference signal means controlled by the output of the comparison means; and an output of the reference signal means and the detection A tracking control circuit comprising: an adding means for adding the output of the adding means; and an information detection point is moved by the output of the adding means.