JPS595461A - Feed driving device - Google Patents

Abstract

PURPOSE:To extend a control range of movement of a pickup, by modulating the height of a pulse when pluse width whose width is applied with width modulation coincides with a sampling interval, and extending a dynamic range of modulation. CONSTITUTION:In case when a period in which an output signal of a pulse width modulating (PWM) circuit 2 becomes L in a sampling period exists, charge of a capacitor C10 which is charged through a resistance R5 from power supply voltage Vcc is made to pass through a diode D1, and is discharged through a resistance R4. In this case, a transistor (TR) Q1 is off, and height of a pulse of a PWM waveform outputted through an amplifier 19 is decided by the gain of an amplifier 10. On the other hand, in case when an H state is continued in an output signal of the circuit 2, terminal voltage of the capacitor C10 rises, its charge makes a diode D2 conduct, and the TR Q1 becomes an on-state. In this case, a resistance R2 is short-circuited by the TR Q1, and height of a pulse in an output terminal 16 becomes twice comparing with height of a pulse in case when an output sigal is not saturated. Such a circuit is used for a feed driving control system.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a feed drive IEJ device that controls the movement of a pickup that reads signals on a video disk using a PWM (Pulse Width Modulation) signal.

Pulse width modulation is a method of quantizing a continuous signal into discrete quantities at a certain sampling interval (frequency) and converting it into a pulse width. In this case, the dynamic range of modulation is determined by the sampling frequency and the minimum pulse gv. limited. Therefore, the maximum pulse width corresponds to the sampling interval, and no more can be generated. That is, since the dynamic range of quantization matches the dynamic range of modulation, if highly accurate quantization cannot be expected, the dynamic range of modulation will be low. Therefore, an object of the present invention is to widen the control range of the # movement of the L pickup by widening the dynamic range of modulation.

In recent years, the commercialization of video discs has attracted attention, especially the optical system, VHD (VHD).
nsi-ty) method, CfcD (Capocitan
Development efforts have been focused on the Ekctionics Disc) method. VTi((Vinθo TapeR
recorder) records video and audio signals on magnetic tape. : Images and audio signals are recorded on a record in the form of finely uneven shapes. For reproduction, this change in shape is converted into an electrical signal by a pickup, and then reproduced by a television receiver (similar to VTI').

VTli vC (Although there is no comparison iPirokuiso tn5, it has high quality image quality.

Umaha is 1 tsubo. 'It is also possible to randomly select the video you want to watch (random access). Furthermore, special playback such as still playback, frame-by-frame playback, frame-by-frame playback, slow motion, and double-speed playback is also possible. v
In the case of the hb system, this random access and special playback are realized by controlling a feed motor that moves a pickup section including a playback needle in the radial direction of the disk. In reality, a tracking signal for making the pickup follow the recorded track of video 1g is written along with the video signal and audio signal on the record, and the tracking signal obtained from the playback needle V is written. φ)D
The C component corresponds to the control sound of the feed motor, and the feed motor is driven in accordance with the operation by a closed loop control system that feeds back the DC component. The DC component of this tracking signal modulates the pulse width to control the NA movement of the feed motor.

Figure 11 shows an example of a conventional control system for a feed motor. The tracking signal obtained by the regeneration needle attached to the pink up (5-pin) is: LPF (Low Pa5sp
i 1t; θr) (1) is multiplied by K, and the pulse width modulation circuit (2) generates a pulse with a width corresponding to the output of the LPF (1) using the trigger pulse (6). The converted signal passes through an amplifier (3) and becomes a signal for controlling the feed motor (4).

Figure 2 shows an example of the basic configuration of the PWM modulation circuit (2) used to modulate the pulse width with the DC component of the tracking signal, and Figure 3 shows an example of the waveform when a continuous signal is converted into a PiVM signal. show. Note that the trinob pulse (6) is a sampling pulse for converting to PWM, and in FIG. 2, the trigger pulse (6) is connected to the terminal (7).
) K is applied. When the trigger pulse (6) is applied to the comparator (8) [hereinafter referred to as CQMF 2], the flip-flop (11 (hereinafter referred to as FIl'1i)
j ' is in the OFF state, and the capacitor CI is connected to the resistor R
It is charged via 1o. And the capacitor ('+)
If Lll7JO is applied to the input continuous signal voltage applied to the input terminal a and the input terminal a, the voltage at the capacitor CI terminal is equal to input No. 16, COMP l (9) The output becomes "H" state, FB'LQ is reset, and the output i becomes IHl. When the output Q becomes H', the transistor (11) becomes tri 'ON' state 9, and the capacitor C3 becomes Discharged. FB'IQO output Qi, J
: ) It is applied to the transistor Oυ and is output as a digital signal to the output terminal σQ via the inverter α. In this way, the input signal voltage and the charging voltage of the capacitor are compared during the sampling period to convert the continuous signal into a pulse width signal.

In Figure 3, (a) is the input continuous signal applied to input terminal αQ, (p) is the trigger pulse (6), and (C) is the input continuous signal generated at output terminal m and applied to amplifier (3). Pulse 1 garden 1 gi number is shown. In addition, in the PV/M conversion in the feed motor control system shown in Fig. 1, Fig. 3 (a) shows the LPF (1
) shows the DC component of tracking No. 18' after passing. Further, the trigger pulse (6) in FIG. 3(b) indicates a field pulse. What is feed pulse? Pickup α
There are 10 pulse trains that occur every time Q follows track V and moves a certain number of tracks. Is (t') in Fig. 3 a PWM-converted signal when (b) is a continuous signal (a)/bring pulse? r Near] No entry.

The pulse IM after the PWM conversion is determined by the capacitor C in FIG. 2, the time constants C1 and R2O by the resistor R1o, and the sampling frequency. The PWM-converted pulse signal [Fig. 3(C)] is amplified and used to drive the feed motor (4). Conventionally, in special playback, feed motors (3-speed continuous mode, 4-speed mode) (
4), this PWM signal is sufficient to track the drive, but if the speed is higher, the trigger pulse train will become denser.
As shown in Figure 4(C), the pulse width reaches the saturated state VCl, so that the pulse 1! The N4 control is disabled, causing a delay in the pickup (5) relative to the truck's starting point. In order to achieve this in the same way as the 3x speed, 4-compensation continuous mode, it is necessary to increase the gain of the amplifier (3). However, if this is done, the pulse width at low speed Nyu must be narrow <Lfx, and the dead zone of the motor,
Control performance deteriorates due to load fluctuations, restrictions on power supply voltage, etc., and shaft followability deteriorates. “F, if we temporarily change the cycle of the trigger nox (6), the relative running of the truck and pickup will also be affected, and another problem will occur, and the solution for t4!4 will be difficult. .

The present invention periodically inputs a relay pulse according to the speed of movement to the drive circuit of a motor that moves a pickup that detects information recorded on a video disk, and varies the input pulse width to move the pickup. The speed is controlled, and the amplitude of the pulse applied to the drive circuit is made larger than when the pulse width does not reach the maximum by determining that the input pulse width has reached the maximum. The pickup control range can be widened by widening the variable dynamometer.

Hereinafter, one embodiment of the invention will be described based on FIGS. 5 and 6. Note that the same function as in Figures 1 and 2 is given by the same matrix and its explanation will be omitted.

Figure 5 shows the narrow configuration of the feed drive device interposed between the LPF (1) and the amplifier (3), Figure 6 (A) shows the signal waveform of the input terminal αQ, and (B) M sampling. Pulse waveform, (C) shows the output waveform of PTVM1 path (2). Book(
If there is an intercostal space in which the output signal of the PWM circuit (2) is sampled J4J)iJ1'P&7m'L' in the ``g)'' path, the charge of the capacitor C2o optically connected from the power supply basket IffvCC via the resistor R5 is: Diode D1
4 through the resistor R4 and discharged through the resistor R4. In this case, the transistor Q, is up to 1 in the 'OFB' state, and the pulse height of the PWM waveform output through the amplifier (IX+1) is determined by the gain of the amplifier 00, in which case the gain is (Ra / ( Therefore, the relationship between the pulse heights of (C) and (middle) in FIG. 6 is expressed by the following equation.

R6 gR, 10R2 However, R and R2 are resistors that connect the PWM circuit (2) and the non-inverting input of amplifier 01, and R6 is a feedback resistor for the amplifier. If the condition continues, the terminal voltage of capacitor CIo will rise. However, the charge on the capacitor C+ojC is diode. In this case, resistor R1 is shorted by transistor Q1,
The gain of increaser 1-04 is (''a/R+), and the strength of the pulse at output terminal 4 is ((Rl+Rt)/R+) compared to the pulse height h.
) times the pulse daytime becomes 1. The gain for the input signal is given by the following equation:

i R.

g R+ Here, the time constant determined by the capacitor C2o and the resistor R3 is such that if the saturated state of the output pulse signal is the trigger pulse - times or U multiple times in succession, the transistor q is '01'.
4-. ．． : It is necessary to set the value VC obtained by increasing the terminal voltage of the capacitor C1o by a certain amount. As explained above, the conventional problems can be solved by using the present invention V in which such a circuit is used in the feed/drive itb control system. In other words, even when driving the feed seventer (4) in high-speed mode, the feed rate is
In Figure 5, if the ratio of R, (!:R2 is set to 1=2,
Since the control discharge range #BA spreads over three lines, tracking becomes faster, and the high-speed mode feed motor (4) can be driven normally by VC without increasing the error in the relative position between the truck on the tire and the pickup. It becomes possible to do so.

Although the above implementation is explained in terms of a special Nyu IQ speed mode of the feed drive control system in a VL-LD video disc player, it is not limited to this embodiment.
Modifications may be made without departing from the spirit of the invention.

As explained above, according to the present invention, when the pulse width modulated in PWM conversion matches the sampling interval, the field of the pulse is modulated by a simple circuit to widen the range of modulation. Compared to the conventional VC, the control range of the movement of the pickup can be expanded without impairing the control 1-11 performance.

[Brief explanation of the drawing]

Fig. 1 is a basic block diagram of a conventional feed drive motor control system, Fig. 2 is a specific circuit diagram of the l'WM circuit shown in Fig. 1, and Figs. FIG. 5 is a configuration diagram of an embodiment of the present invention, and FIG. 6 is a waveform diagram of the main part of FIG. 5. (1)...Low pass filter, (2)...PWM circuit, (3)...Amplifier, (4)...Feed motor''
(5)...Pickup, (6)...Trigger pulse, OL...Amplifier, Equal +R1+R* *R6...
, resistance, C4゜...capacitor, Qbi...transistor agent Yoshihiro MorimotoFigure 1Figure 2Figure 3Figure 4Figure 4S Figure θFigure

Claims (1)

[Claims] L Pulses are periodically input into the drive circuit of the motor that drives the big amplifier that detects the information recorded on the video disc, depending on the speed of movement, and the width of the manually inputted pulses is varied to control the speed of movement. and detects that the input pulse width has reached a maximum, and makes the amplitude of the pulse input to the drive circuit larger than when the pulse width does not reach the maximum V. Configured feed drive device.