JPH02151288A - Speed controller - Google Patents

Abstract

PURPOSE:To remove sound generated from a carriage at the time of control of a speed by converting a sine wavelike position signal into a triangular wavelike position signal. CONSTITUTION:A position signal (p) is converted into a sine bit (d) and 8-bit digital signal a0-a7 with the position signal (p) and a clock (h) formed by an oscillation circuit 202 by means of a 8-bit+sine bit.A/D converter 200. A memory 201 inputs address a0-a7, and converts them into 8-bit digital signals b0-b7 corresponding to bit conversion. Then, a position signal p' is output as an analog signal by the sine bit (d) and the 8-bit digital signals b0-b7 by means by a D/A converter 203, and a sine wavelike position signal (p) is converted to a triangular wavelike position signal p'. An output signal n' of an inverted output of the position signal (p) is output by an inverting amplifier 12 having 1 of an amplification factor. The position signals p', n' are replaced with the inputs of the position signals p, n thereby to prevent a sound from a carriage at the time of control of a speed without ripple at a speed signal (v).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to speed control of a voice coil motor in a positioner of an optical disk device.

[Conventional technology]

Fig. 5 shows the principle structure of a voice coil motor used in the positioner of an optical disk device, which includes a magnetic circuit with a permanent magnet 2 that generates a -like magnetic flux in the gap 1, and a magnetic circuit that generates magnetic flux in the gap 1. , the voice coil 3 receives a linear force.

Since the voice coil 3 is fixed to the carriage ridge 4, the carriage ridge 4 also moves with linear force.

The sensor 5 that detects the mutual position of the carriage 4 and the fixed table 7 and generates a sinusoidal position signal includes an optical system sensor, a magnet scale, an inductosin, a magnetic tachometer, etc. , we will discuss the case of an optical sensor.

A scale 6 is attached to the carriage 4. The sensor 5 is fixed to the stand 7.

FIG. 6 shows the structure of the sensor 5. Light emitted from the light emitting element 8 passes through the scale 6, passes through the scale 9 fixed to the sensor 5, and is detected by the light receiving element 10 (scales 6 and 9). (The slit patterns should be the same pitch.)

FIG. 7 is a block diagram of a conventional speed detection device. The output signal a of the sensor 10 is outputted by the offset adjustment amplifier circuit 11 as a position signal p. Inverting amplifier 1 with amplification factor 1
2, a reverse rotation output n of the position signal p is output. A current signal i flowing through the voice coil 3 is sent to a constant current power amplifier 16.
When the 0 position signals p and n and the current signal i which are made to be output from the speed detection circuit 13 are inputted, the speed signal V
Output. The speed function generation circuit 14 outputs a speed function signal f. The differential amplifier circuit 15 outputs a speed difference signal S which is an amplified difference signal between the speed signal V and the speed function signal f. When the constant current power amplifier 16 receives the speed difference signal S, it can output the voice coil drive voltage e and control the speed of the voice coil 3 to a target speed.

FIG. 8 shows a detailed explanation of the speed detection circuit 13, and FIG. 9 shows a time chart of the speed detection circuit 13.

The voltage comparison circuit 100 outputs a sense signal S when the position signal p becomes 60% or less of the negative peak value of the position signal p. Similarly, the voltage comparison circuit 101 outputs the sense signal C when the position signal n becomes 60% or less of the negative peak value of the position signal n. The OR circuit 102 outputs a switch signal SO obtained by ORing the sensor signal S and C.

The S-R flip-flop circuit 103 has the sense signal already set, and the switch signal SO is inverted by the 0 inverting circuit 104 which outputs the latch signal q reset by the sense signal C and the inverted latch signal q. outputs the switched switch signal SO. The AND circuit 105 outputs a switch signal s1 obtained by ANDing the inverted switch signal S0 and the latch signal q. The AND circuit 106 outputs a switch signal S2 obtained by ANDing the inverted switch signal i and the inverted latch signal 〒.

A differential circuit made of a capacitor 107 and a resistor 108 outputs a differential signal ρV of the position signal p. A differential circuit made of a capacitor 109 and a resistor 110 outputs a differential signal nv of the position signal n. analog switch 1
11 becomes conductive only when the switch signal s1 is received. Analog switch 112 becomes conductive only when switch signal S2 is received. Resistor 113 is used to input a zero potential signal to the voltage follower when analog switches 111 and 112 are not conducting.

Only when the switch signals s1 and 82 are present, the voltage follower 114 outputs the speed signal V', but when the switch signals s1 and 52 are not present, the speed signal V' is at zero potential. To compensate for this, the integral of the constant current signal i (proportional to acceleration) is used (the integral of acceleration is proportional to speed).

The analog switch 116 becomes conductive only when the inverted switch signal 1 becomes -. When the switch signals s1 and s2 are applied, the inverted switch signal sO is applied, so the analog switch 116 is conductive and the operational amplifier 119 is turned on.
is an amplification factor determined by the resistor 117 and the resistor 115, and amplifies the speed signal V' and outputs the speed signal V.

When the switch signals s1 and s2 are not coming, the switch signal SO is also not coming, so the analog switch 11
6 is not conducting, the operational amplifier 119 becomes an integrating circuit with the capacitor 118 and the resistor 120, and the current signal i
is integrated and a speed signal V is output. If the value of the resistor 120 is made much larger than the value of the resistor 117, the current signal i has almost no effect on the speed signal V when the analog switch 116 is conductive. The speed signal V at this time is the 9th
It will look like the time chart in the figure.

[Problem to be solved by the invention]

Since the position signals p and n are sinusoidal signals, small ripples occur in the differential signals pv and nv obtained by differentiating the position signals p and n. According to Figure 7,
When the difference signal between the speed signal V and the speed function signal f is greatly amplified by the differential amplifier circuit 15, this ripple becomes a considerably large signal. Therefore, when controlling the speed,
When the voice coil 3 of the carriage ridge 4 is controlled by a drive voltage with this ripple, a sound is generated from the carriage ridge 4 when the frequency of the ripple matches the natural vibration of the carriage ridge 4, and if it gets worse, the speed control is stopped. become unable to do so.

Also, if you try to remove the ripple by passing it through a low-pass filter, you will need a fairly low-pass filter. If this low-pass filter is used, the rise and fall of speed control will be poor, making control impossible.

[Means to solve the problem]

According to the present invention, [a position sensor that detects the position of the motor as a sinusoidal position signal; an offset adjustment means that performs offset adjustment of the output signal from the position sensor; and an output signal of the offset adjustment means that detects the position of the motor in the form of a triangular wave position. a function conversion circuit that converts the output signal into a signal; an inversion unit that inverts the output signal of the function conversion circuit; and detects the speed of the motor based on the output signal of the function conversion circuit, the output signal of the inversion unit, and the current signal of the motor. a speed detection circuit that generates a speed function; a differential amplifier circuit that amplifies a difference between an output signal of the speed detection circuit and an output signal of the speed function generation circuit; and the differential amplifier circuit. and a constant current power amplifier that converts the output signal of the motor into a motor current.

〔Example〕

Next, the present invention will be described in more detail with reference to the drawings showing one embodiment of the present invention.

Referring to FIG. 1, the difference between the embodiment of the present invention and the conventional example shown in FIG. be.

FIG. 2 shows a detailed explanation of the function conversion circuit 17.

Using the position signal p and the clock h generated by the oscillation circuit 202, the 8-bit + sign bit analog/digital converter 200 converts the analog signal (position signal p) into a sign bit d and 8-bit digital signals aO to a7. . The memory 201 inputs addresses aO to a7, and
It is converted into 8-bit digital signals bO to b7 corresponding to the bit conversion shown in the figure.

Next, an 8-bit + sign bit digital/analog converter 203 outputs a position signal p as an analog signal using the sign bit d and the 8-bit digital signals bo to b7. This conversion converts the sinusoidal position signal p into a triangular position signal p'. An inverting amplifier 12 with an amplification factor of 1 generates a position signal n which is an inverted output of the position signal p.
Output. By replacing these position signals p', n with the position signals p, n input of the conventional circuit (Fig. 7), the speed signal V no longer contains ripples as shown in the time chart of Fig. 4, and the speed control Sometimes the cause of the sound generation from the car ridge disappears.

〔Effect of the invention〕

As explained above, according to the present invention, by converting a sinusoidal position signal into a triangular position signal, the speed signal no longer contains ripples, and the sound generated from the carriage during speed control can be eliminated. can.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a detailed block diagram of the function conversion circuit 17 in this embodiment, and FIG.
The figure shows bit conversion in the function conversion circuit 17,
Fig. 4 is a time chart in this embodiment, Fig. 5 is a principle structural diagram of the voice coil motor, Fig. 6 is a structural diagram of the sensor 5, Fig. 7 is a block diagram of a conventional speed control device, and Fig. 8 is a block diagram of a conventional speed control device.
The figure is a detailed block diagram of the speed detection circuit 13, and FIG. 9 is a time chart in the speed detection circuit 13. 1... Gap 2... Permanent magnet 3... Voice coil 4... Carriage 5... Sensor 6... Scale 7... Base 8... Light emitting element 9... Scale , 10... Light receiving element 11... Offset adjustment amplifier circuit 12... Inverting amplifier with amplification factor of 1 13... Speed detection circuit 14... Speed function generation circuit 15... Differential amplifier circuit 16. ...Constant current power amplifier 17...Function conversion circuit 100.101...Voltage comparison circuit, 102...OR circuit 103...S-R flip-flop circuit 104...
Inverter circuit 105.106...Logic ff circuit 107.109.118...Capacitor 108.11
0,113,115,117°120...Resistor 111.112.116...Analog switch 114
... Voltage follower 119... Operational amplifier 200... 8 bits + sign bit analog/digital converter 201... Memory 202... Oscillation circuit 203... 8 bits + sign bit digital/analog conversion vessel. Agent Patent Attorney Susumu Uchihara Figure 2 Figure 2 Roza (G) Sununagi'g ≦1 Ikko~ (1) φ Furnace Figure S2 Easy 1 blade

Claims (1)

[Scope of Claims] A position sensor that detects the position of the motor as a sinusoidal position signal; an offset adjustment means that adjusts the offset of the output signal from the position sensor; and an output signal of the offset adjustment means that converts the output signal into a triangular position signal. a function conversion circuit for converting the output signal into the function conversion circuit; an inversion unit for inverting the output signal of the function conversion circuit; and detecting the speed of the motor based on the output signal of the function conversion circuit, the output signal of the inversion unit, and the current signal of the motor. a speed detection circuit; a speed function generation circuit that generates a speed function; a differential amplifier circuit that amplifies a difference between an output signal of the speed detection circuit and an output signal of the speed function generation circuit; A speed control device comprising a constant current power amplifier that converts an output signal into a motor current.