JPS631671B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a feed pulse generation circuit, in which a capacitor of a Miller integration circuit is charged with a tracking error signal, and the discharge of this capacitor is used to reduce the capacitance of the capacitor and eliminate unnecessary It is an object of the present invention to provide a feed pulse generation circuit that does not generate feed pulses.

The present applicant has proposed that the main information signal and the first to third tracking control reference signals (hereinafter referred to as "tracking signals") f _p1 to f _p3 each have a change in geometrical shape without first forming a needle guide groove. A disk-shaped information recording medium (hereinafter referred to as "disk") having an electrode function recorded as , and relative sliding scanning of it with a reproducing needle having electrodes generates the main information signal and the first to third tracking signals.
We proposed a reproducing device that reads and reproduces f _p1 to f _p3 as changes in capacitance.

Therefore, in the disc reproducing apparatus proposed by the present applicant, the feed feeding device for transporting the regenerating needle in the radial direction of the disc is configured to transport the reproducing needle in the radial direction of the disc using a DC motor. Therefore, the transfer speed can be controlled by controlling the rotational speed of the DC motor by changing the period and pulse width of the feed pulse applied to the DC motor. During normal playback (normal playback, slow motion playback, quick motion playback, etc.), the error caused by the movement of the tip of the playback needle due to feed feed changes to the DC component of the tracking error signal. In order to correct this feed feeding error, the pulse width of the feed pulse is varied in accordance with the DC component of the tracking error signal. It is clear that in a DC motor, if the repetition frequency of the applied feed pulse is the same, the rotation angle increases in proportion to the pulse width.

FIG. 1 shows a circuit diagram of an example of a feed pulse generation circuit previously proposed by the applicant. In the same figure,
At the input terminal 1, the first and second tracking signals f _p1 and f _p2 are discriminated and separated during playback of the disc;
After detecting them, a tracking error signal is input into the differential amplifier at a level corresponding to the relative level difference between the two (that is, a level corresponding to the amount of track deviation) and a polarity corresponding to the direction of the track deviation.
Supplied to R ₁ . The resistor _R1 and the capacitor _C1 constitute an integrating circuit, and the tracking error signal is supplied to the switch S1 after high frequency components are removed by this integrating circuit. A control signal corresponding to the feed feed direction is supplied to the switch S1 via an input terminal 2, and the switch S1 is switched to supply the signal from the integrating circuit to an inverting input terminal or a non-inverting input terminal of an amplifier 3 at the next stage. The amplifier 3 inverts or non-inverts the signal from the integrating circuit and supplies it to the pulse width modulator 4 as a tracking error signal with a voltage value of 0V or more. This pulse width modulator 4 is triggered by a pulse supplied from an input terminal 5 every 32 tracks of the disc during normal playback, and is fed with a feed pulse whose pulse width is varied according to the voltage value of the tracking error signal from the amplifier 3. is generated and supplied to switch S2. A control signal is supplied to the switch S2 from the input terminal 2, and this causes the feed pulse to be sent to the amplifier 6.
is supplied to the inverting input terminal or non-inverting input terminal of
The amplifier 6 inverts or non-inverts the feed pulse and outputs it as a feed pulse with a polarity according to the feed feeding direction via the output terminal 7,
A feed motor (not shown) is rotated in the forward or reverse direction to move the regeneration needle to the inner or outer side of the disk.

In this circuit, it is necessary to use a non-polar capacitor _C1 having a large capacity of 22 μF, for example, which constitutes the integrating circuit. Also, for example, if a pulse is supplied from the input terminal 5 while the regeneration needle is tilted toward the outer circumference, the regeneration needle will track toward the inner circumference over time, so there is no need to feed the feed. A feed pulse is generated and the feed is fed uniformly. On the other hand, there is a drawback in that unnecessary feed is similarly performed when the reproduction needle is inclined toward the inner circumference during backward reproduction.

The present invention eliminates the above-mentioned drawbacks,
One embodiment thereof will be explained with reference to FIG. 2 and the following figures.

FIG. 2 shows a circuit diagram of one embodiment of the feed pulse generating circuit according to the present invention. In the figure, the same parts as in FIG. 1 are given the same reference numerals. In Fig. 2, input terminal 1 is used to distinguish and separate the first and second tracking signals f _p1 and f _p2 during disc playback, and after detecting them, a differential amplifier outputs a level corresponding to the relative level difference between the two. (that is, a level corresponding to the amount of track deviation), a tracking error signal whose polarity corresponds to the direction of track deviation is input, and the resistance R ₂
is supplied to terminal S3a of switch S3 via. Switch S3 is flip-flop 1, which will be described later.
A low level control signal is supplied from 0 to the terminal S.
3a and terminal S3c are connected, and the tracking error signal is supplied to the inverting input terminal of operational amplifier 11. The operational amplifier 11 constitutes a Miller integration circuit together with the capacitor C ₂ and the resistor R ₂ whose ends are connected to its output terminal and the inverting input terminal, and the capacitor C ₂ is charged to a polarity according to the polarity of the tracking error signal. be done.

Here, the flip-flop 10 is set by a pulse from the input terminal 5 applied to its set terminal, but this pulse is not set during normal playback (during normal playback, fast motion playback, slow motion playback, etc.). is a pulse that is generated, for example, once every 32 tracks on the disk are reproduced. Therefore, flip-flop 10 is, for example, 32
During track playback (every 2.1 seconds during normal playback)
is set to The Q terminal output of flip-flop 10 is supplied to switches S3 and S4, and Q
When the terminal output becomes high level, switch S3 connects terminal S3b and terminal S3c and connects the capacitor.
The charge charged in C ₂ is discharged through resistor R ₃ . The voltage generated at the output terminal of the operational amplifier 11 is supplied to a comparator 12 and compared with zero potential, and the comparator 12 outputs a high level (0V or more) or a low level (0V or less) depending on the charged polarity of the capacitor _C2 . generates a rectangular wave whose pulse width corresponds to the charge of the capacitor _C2 charged by the tracking error signal, and sends this to the switch S.
4 and the inversion detector 13.
FIG. 3 shows the state of the voltage across capacitor _C2 .
When the regeneration needle is tilted greatly toward the inner circumference of the disk, the polarity is positive and the voltage is high, as shown by the broken line in Figure 3, and the discharge begins at time t ₁ and ends at time t ₃ . The output of the comparator 12 is at a high level and becomes a rectangular wave with a pulse width of t ₃ −t ₁ . When the regeneration needle is slightly tilted inward, the voltage is low and the discharge time is short, t ₂ - t ₁ , as shown by the broken line in Figure 3, the output of the comparator 12 is at a high level, and the pulse width is t ₂ - t. It becomes ₁ .

Similarly, when the playback needle is tilted toward the outer circumference of the disk, the polarity becomes negative as shown by the broken line in Figure 3, the absolute value of the voltage is proportional to the tilt angle, and the output of the comparator 12 is at a low level with a pulse width. are each
t ₂ −t ₁ , t ₃ −t ₁ . The inversion detector 13 detects when the rectangular wave is inverted from a low level to a high level or from a high level to a low level, supplies a detection signal to the reset terminal of the flip-flop 10 to reset the flip-flop 10, and outputs the Q terminal of the flip-flop 10. The output becomes low level.

The switch S4 is closed when a high level signal is supplied from the flip-flop 10, and is opened when the signal is low level, and connects the rectangular wave from the comparator 12 to the anode of the diode _D1 and the diode _D2.
supply to the cathode of The cathode of diode _D1 is connected to terminal S5a of switch S5, and the anode of diode _D2 is connected to terminal S5b of switch S5.
Terminal S5c of switch S5 is connected to terminal S5a and S5c according to the feed direction according to the control signal supplied from input terminal 2. For example, when feed is to be fed in the direction of the inner circumference of the disc, terminals S5a and S5c are connected to feed in the direction of the outer circumference. For feed feed, use terminal S5
b, connect S5c. As a result, the above-mentioned rectangular wave is extracted from the switch S5 as a positive polarity feed pulse for feeding in the inner circumferential direction or a negative polarity feed pulse for feeding in the outer circumferential direction, and is outputted from the output terminal 14.

For example, during normal playback, when the playback needle is tilted toward the outer circumference and the feed is to be fed in the inner circumferential direction, a low level signal (0V or less) is sent from the comparator 12 to the switch S4.
and is supplied to the terminal S5b of the switch S5 through the diode _D2 , but the switch S5 is supplied to the terminal S5b of the switch S5.
Since a and S5c are connected, there is no feed pulse output from the output terminal 14, and feed feeding is not performed. In this case, the regeneration needle tracks toward the inner circumference with time. Furthermore, when performing feed feeding in the outer circumferential direction with the reproduction needle tilted toward the inner circumference during backward reproduction, the above is reversed, and the explanation thereof will be omitted.

Furthermore, since the above circuit uses a Miller integration circuit, the capacitance of capacitor C ₂ is 1/A of the capacitance of capacitor C ₁ shown in the first diagram (that is, C ₂ = C ₁ /A) is sufficient, the size is small and the cost is low.

As described above, the feed pulse generating circuit according to the present invention includes a Miller integrating circuit having a capacitor charged by a tracking error signal, and a rectangular pulse having a polarity corresponding to the discharge direction and a pulse width corresponding to the discharge time when the capacitor discharges. A circuit that generates a wave, a first switch that charges a capacitor when supplied with a signal instructing to start the feed, and discharges the capacitor when the polarity of the rectangular wave is reversed; It consists of a rectifier circuit that extracts either the positive or negative polarity side of the wave and uses it as a feed pulse, and a second switch that works in conjunction with the first switch to supply a rectangular wave to the rectifier circuit when the capacitor discharges. , the electrostatic capacitance of the capacitor is small, and unnecessary feed pulses are not generated.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of an example of a conventional feed pulse generation circuit, Fig. 2 is a circuit diagram of an embodiment of the feed pulse generation circuit according to the present invention, and Fig. 3 is a voltage of capacitor C _{2 shown in Fig. 2} . It is a figure showing a state. 1, 2, 5...input terminal, 3, 6...amplifier,
4... Pulse width modulator, 7, 14... Output terminal,
10...Flip-flop, 11...Operation amplifier, 12...Comparator, 13...Inversion detector, S1 to S5...Switch, _R1 to _R3 ...Resistance,
C ₁ , C ₂ ... Capacitor, D ₁ , D ₂ ... Diode.

Claims (1)

[Claims] 1. In a circuit that generates a feed pulse with a pulse width corresponding to the DC component of a tracking error signal of the reproducing element in order to move the reproducing element that picks up and reproduces a recorded signal on a disk-shaped information recording medium in the radial direction of the recording medium, A Miller integration circuit having a capacitor charged by the tracking error signal, a circuit that generates a rectangular wave with a polarity corresponding to the discharge direction and a pulse width corresponding to the discharge time when the capacitor discharges, and a feed start instruction. a first switch that charges the capacitor when it is supplied with a signal and discharges the capacitor when the polarity of the rectangular wave is reversed; A rectifier circuit which extracts one of the negative polarity side as a feed pulse, and a second switch which operates in conjunction with the first switch and supplies the rectangular wave to the rectifier circuit when the capacitor discharges. Feed pulse generation circuit.