JPH026556Y2 - - Google Patents

Description

[Detailed description of the invention] The invention relates to a disk-shaped information recording medium reproducing device,
A reproducing device having a configuration in which a tracking error signal is clamped and supplied to a reproducing needle transporting body drive circuit, and is capable of preventing runaway of the reproducing needle transporting body even if the tracking error signal becomes a value different from that at the time of reproduction due to some reason. The purpose is to provide

The present applicant has previously developed an electrode function in which the main information signal and the reference signal for tracking control (hereinafter referred to as the tracking signal) are recorded in a spiral shape as changes in their respective geometric shapes without forming a needle guide groove. We have proposed a reproducing apparatus that reads and reproduces the above-mentioned signals by slidingly scanning a disk-shaped information recording medium (hereinafter referred to as a disk) and a reproducing needle having electrodes. Specifically, in the disk 1, two types of tracking signals f _P1 and f _P2 having different frequencies are input to the outer circumferential side and the inner circumferential side at each rotation on both sides of a main information signal track provided in a spiral shape. It has been changed and recorded.

FIG. 1 shows a schematic block system diagram of an embodiment of a disc reproducing apparatus according to the present invention for reproducing such discs. As shown in Figure 1, disk 1
The signals read by the reproducing needle 2 are extracted as video and audio signals by the reproducing circuit 3, and are supplied to filters 4 ₁ and 4 ₂ to become tracking signals f _P1 and f _P2 , respectively, and are sent to the switch circuit. 5 and is recorded every rotation of disk 1.
f Can be switched with _P3 .

By this switching, tracking signals f _P1 , f _P2
is alternately switched every rotation of the disk 1 and supplied to the differential amplifier of the drive control circuit 6, and is used as a tracking error signal. This tracking error signal has a level corresponding to the amount of tracking deviation of the regeneration needle 2 and a polarity according to the tracking deviation direction, and is supplied to the tracking coil 2a of the regeneration stylus 2, so that the regeneration stylus 2 is the main one. Driving in the tracking direction is controlled so as to accurately trace the information signal track.

At the same time, during normal playback and 1/2x speed,
During trick playback at 1/4x speed, 2x speed, 4x speed,...61x speed, etc. (all modes that require normal tracking control), the tracking error signal is sent to the regeneration needle transport body (carriage) drive circuit 7. The signal is supplied as a carriage drive signal, and the carriage 8
is transported in the radial direction by this carriage drive signal. As a result, the reproducing needle 2 is moved such that there is no inclination with respect to the track direction of the disk 1, and the main information signal is reproduced.

During normal playback or trick playback, for example, if the disk 1 is damaged or has dust attached, the playback needle 2 may become out of track, and as a result, the drive control circuit 6 The output voltage becomes an extreme value (for example, about ±12V) compared to normal control (about +1V during normal playback, about ±1.8V during trick playback). This extreme voltage is applied to the carriage drive circuit 7, and the carriage 8 is displaced by an amount extremely different from the amount of displacement during normal playback, causing it to run out of control in the radial direction of the disk 1. There is a risk of damage.

Therefore, the device of the present invention is designed to prevent a signal exceeding a predetermined value from being supplied to the carriage drive circuit no matter what the value of the tracking error signal is.

FIG. 2 shows a specific circuit diagram of a drive control circuit used in one embodiment of the device of the present invention. In the figure, reference numeral 9 denotes a differential amplifier which detects the difference between the tracking signals from the switch circuit 5 and outputs a tracking error signal, the output of which is phase compensated and then supplied to the tracking coil 2a. 10 is a phase compensation amplifier having a low-pass filter, and its output terminal 6a is connected to a carriage drive circuit 7. Amplifier 1
By connecting a capacitor and a resistor to 0 as shown in FIG. 2, an integrating circuit consisting of a negative feedback type operational amplifier is constructed.

The output terminal 6a has a resistance R ₁ (1kΩ) and a resistance R ₂ (10kΩ).
It is connected to a negative power supply (-12V) via a resistor R 3 (1kΩ) and a positive power supply (+12V) via a resistor R ₃ (1kΩ) and a resistor R ₄ (10kΩ), respectively. resistance
A diode D _a is connected between the connection point a of R ₁ and R ₂ and the input terminal of the amplifier 10, with its anode on the connection point a side,
A diode D _b is connected between the connection point b of the resistors R ₃ and R ₄ and the input end of the amplifier 10 with its anode connected to the input end of the amplifier 10. side, with its cathode at the connection point b side.

When the tracking error signal is output from the amplifier 9, this tracking error signal is phase compensated and then supplied to the tracking coil 2a, while the phase is compensated by the amplifier 10 and output to the output terminal 6a.
It is taken out and supplied to the carriage drive circuit 7. In this case, in a mode in which tracking control is applied, such as during normal playback or trick playback, the output of the amplifier 10 has a voltage determined by resistors R ₁ and R ₂ or a voltage determined by resistors R ₃ and R ₄ . (As mentioned above, during normal playback, about +1kV,
During trick regeneration, approximately ±1.8V) is extracted.
During trick regeneration, the kick pulse is extracted and combined with a tracking error signal, and the regeneration needle 2 is forcibly moved one track by this combined signal, but such a high frequency signal The configuration is such that the signal is removed by the low-pass filter of the amplifier 10 and not taken out as its output. Since the tracking error signal supplied to the tracking coil 2a does not pass through the amplifier 10, the kick pulse combined with the tracking error signal is transmitted to the tracking coil 2a.
The tracking coil 2a then moves the regeneration needle 2 in response to the kick pulse. In this way, the tracking coil 2a is
The tracking error signal supplied to the carriage drive circuit 7 is different from the tracking error signal supplied to the carriage drive circuit 7.

Let us now consider a case where there is dust or the like on the disk 1 and the tracking error signal has a value that is extremely different from that during normal control. In this case, the output voltage of the amplifier 9 has a certain time constant (at a lower frequency than when the above kick pulse is generated).
becomes an extreme value.

However, even if an abnormal voltage is to be output to the output terminal of the amplifier 10, diodes D a and D b are connected between the point a and the input terminal of the amplifier 10 and between the point _b and the input terminal of the amplifier ₁₀ . Since it is connected, point a
The potential at point b is clamped to the potential due to the forward voltage of diodes D _a and D _b , and the potential at point a is +
0.6V or higher, the potential at point b will never be lower than -0.6V (in either case for a silicon diode). Therefore, no matter what value of voltage is to be output to the output terminal 6a of the amplifier 10, the potential of the output terminal 6a is controlled by the resistors R ₁ , R ₂ , the positive power supply, and the resistor R ₃ ,
R ₄ can be suppressed to a value determined by the negative power supply.

In this case, no matter what voltage value is applied to the input of the amplifier 10, the output of the amplifier 10 is the voltage (±1.8 V
The voltage is selected so as not to exceed the absolute value of a voltage (for example, about ±2V) that is slightly higher than For this reason, even if the tracking error signal becomes an extremely different value from that during normal control and an abnormal voltage of about ±12V is output to the output of the amplifier 10, the voltage at the terminal 6a will be about ±2V. suppressed by
As a result, no abnormal voltage will be applied to the carriage drive circuit 7, and the carriage 8 will not run out of control.

By configuring an integrating circuit using the amplifier 10, the integrating circuit becomes a low-pass filter, so that kick pulses can be removed. Therefore, it is possible to prevent the kick pulse from having an adverse effect on tracking control.

As described above, the disc playback device according to the present invention includes a drive control circuit that includes a detector that detects the difference between two tracking control reference signals, an output signal of the detector is supplied to an inverting input terminal, and an output signal is supplied to the inverting input terminal. an integrating circuit consisting of a negative feedback operational amplifier whose terminal is connected to the drive circuit; a first dividing resistor whose one end is connected to the negative power supply and whose other end is connected to the output terminal; a second divided resistor connected to the positive power supply and whose other end is connected to the output terminal; an anode connected to the first divided resistor and a cathode connected to the inverting input terminal; Since it is composed of a first diode and a second diode whose anode is connected to the inverting input terminal and whose cathode is connected to the second dividing resistor, it is possible, for example, to play back a disk with dust attached. As a result, even if the tracking error signal becomes an abnormal value different from that during normal reproduction, this abnormal voltage will not be applied to the drive circuit, and as a result, the reproduction needle transport body will not run out of control and will always The regenerated needle can be transported in a normal state without damaging the regenerated needle or disk, and since the disturbance caused by the regenerated needle transport body can be prevented in this way, the tracking control system will not be adversely affected. It has characteristics.

[Brief explanation of the drawing]

FIG. 1 is a schematic block system diagram of one embodiment of the device of the present invention, and FIG. 2 is a specific circuit diagram of a drive control circuit used in the device of the present invention. DESCRIPTION OF SYMBOLS 1... Disc-shaped information recording medium (disc), 2... Playback needle, 2a... Tracking coil, 6... Drive control circuit, 6a... Output terminal, 7... Carriage drive circuit, 8... Playback needle transport body (carriage), 9 ...Differential amplifier, 10...Phase compensation amplifier, _R1 to _R4 ...Resistor,
D _a , D _b ...diodes.

Claims (1)

[Claims for Utility Model Registration] A drive circuit that is supplied with a tracking error signal for tracking control of the reproducing element and transports the reproducing element transporting body to which the reproducing element is attached in the radial direction of the disc-shaped information recording medium. , a disk-shaped drive control circuit which clamps the tracking error signal so that it does not exceed the value output during playback under the tracking control no matter what value it becomes, and supplies the tracking error signal to the drive circuit. An information recording medium reproducing apparatus, wherein the drive control circuit is supplied with two tracking control reference signals read from the disc-shaped information recording medium via the reproducing element, and the two tracking control reference signals are supplied to the drive control circuit. an integrating circuit consisting of a negative feedback operational amplifier whose output terminal is connected to the drive circuit and whose output terminal is connected to the drive circuit; a first divided resistor connected to the positive power supply and whose other end is connected to the output terminal; and a second divided resistor whose one end is connected to the positive power supply and whose other end is connected to the output terminal. a resistor, a first resistor having an anode connected to the first dividing resistor and a cathode connected to the inverting input terminal;
and a second diode having an anode connected to the inverting input terminal and a cathode connected to the second dividing resistor.