JPH0319141A - Driving voltage generation circuit - Google Patents

Abstract

PURPOSE:To reduce power consumption and to prevent circuit constitution from being complicated by constituting the subject circuit by means of a maximum driving voltage detection circuit and a PWM voltage conversion circuit converting a power voltage supplied to respective driving circuits into a PWM voltage by means of a signal based on a maximum driving voltage to be detected. CONSTITUTION:The subject circuit is constituted of a comparator 32, comparing a maximum control signal from a maximum control signal detection circuit 15 with an action voltage VPWM obtained by switching the power voltage from a power source 27 in a transistor 28, a PWM voltage generator 33 comparing a voltage from the comparator 32 with a sawtooth signal from a sawtooth oscillator 34 and obtaining the PWM voltage. The maximum control signal among control signals from respective driving circuits 1a-1d is detected in the maximum control signal detection circuit 15 and the power voltage is PWM- controlled by the maximum control signal. Since an action voltage for respective driving circuits 1a-1d is controlled to a necessary level, power consumption is reduced. Furthermore, the PWM voltage conversion circuit 26 is set to be common and therefore circuit constitution is prevented from being complicated.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Industrial Application Field The present invention relates to a drive voltage generation circuit used for supplying drive current to a tracking coil, focus coil, spindle motor, etc. in a disc player or the like. 〉Prior art For example, the actuator of a CD player is composed of a pickup force control, a tracking coil, a feed motor for moving the pickup itself, and a spindle motor. As described in the publication, a photodetector detects the irradiation deviation of the light beam onto the track, generates a tracking error signal, and applies the tracking error signal to a tracking film,
Tracking of the light beam is performed. When tracking is no longer possible by simply applying a tracking error signal to the tracking coil, the signal is supplied to the pickup remoter to move the entire pickup and perform tracking. Furthermore, as described in Japanese Patent Application Laid-open No. 63-193332, a photodetector using a half mirror or the like detects the deviation of the spot of the light beam on the disk surface, and generates a focus error signal. A focus error signal is applied to the focus coil and the objective lens is moved in a direction perpendicular to the disk surface, so that the light beam is always focused on the disk surface. Furthermore, in CD players, servo signals are obtained using synchronization signals extracted from information signals recorded on the disc, and these servo signals are supplied to the spindle motor so that the disc always rotates at a constant linear velocity. I have to. (c) Problems to be Solved by the Invention As mentioned above, in a CD player, a control signal is supplied to an actuator such as a tracking coil or a focus coil so that the actuator is operated correctly.

By the way, a power operational amplifier is used for each actuator, and a detection signal from a detection means is applied to the power operational amplifier to control the voltage applied to each actuator from the power supply. This series control method consumes power, making it unsuitable for portable CD players. As mentioned above, the series control method has the drawback of high power consumption, and as a method to improve this drawback, a method of PWM (pulse width conversion) of the power supply voltage applied to each actuator has been used. This PWM system has the disadvantage that noise generated by actuator switching easily enters the signal path of the start-up, and it is necessary to provide a PWM circuit for each actuator. The present invention provides a drive voltage generation circuit that eliminates the above drawbacks.

(Means for Solving Two Problems) The drive voltage generation circuit of the present invention includes a plurality of drive circuits that supply drive voltages to the drive means in accordance with the detected current detected by the detection means, and a drive voltage generated by the drive circuits. A maximum drive voltage detection circuit that detects the maximum drive voltage detected, and a PWM voltage conversion circuit that performs PWM voltage conversion of the power supply voltage supplied to each drive circuit using a signal based on the detected maximum drive voltage. .

Furthermore, the plurality of drive circuits include a comparison circuit that generates a control signal and a rotation direction instruction signal, and a drive circuit that is operated by these control signals and rotation direction instruction signals and generates drive currents for the focus coil, tracking coil, and spindle motor, respectively. It consists of means. (E) Effect The drive voltage generation circuit of the present invention has the above-described configuration, in which the maximum control signal among the control signals from each drive circuit is detected by the maximum control signal detection circuit, and the maximum control signal is used to detect the power supply voltage. PWM control is performed to reduce the power consumption of the operating voltage supplied to each of the dynamic circuits.

(F) Embodiment An embodiment of the drive voltage generation circuit of the present invention will be described with reference to the drawings.

In the figure, (la) to (ld) are drive circuits that supply drive current to the force control coil, the tracking coil, the pickup feed motor, and the spindle motor.
Each drive circuit (1a> to (1d) has the same circuit structure, for example, the drive circuit (1a> has a reference voltage (Vref)
an input terminal (2) to which a focus shift signal (VC■) is applied, an input terminal (3) to which a focus shift signal (VC) corresponding to the focus shift is applied, and a focus control device that amplifies the absolute value of the difference between the reference voltage and the focus shift signal. An absolute value amplifier (4) that takes out the signal (VMI), a comparator (5) that compares the magnitude of the reference voltage and the focus shift signal and generates a motion direction instruction signal, the focus control signal (Vvs) and the motion direction instruction. a logic circuit (6) for processing a signal; and an operational amplifier (7), one of which is operated by the signal from the logic circuit (6) and amplifies the focus control signal (1).
(8), the operational amplifier (7) (8) and the logic circuit (
A transistor (9) that is selectively turned on by a signal from (6)
) to (12), and each of the transistors (9) to (12)
) and moves the objective lens (not shown) in a direction perpendicular to the disk surface.
and (15) represents each of the drive circuits (1a> to (1a)
1d) is a maximum control signal detection circuit that detects the largest control signal among the control signals obtained from the output terminals (14a) to (14d), and the control circuits (la) to (ld) output terminals (14a) to (1
a differential amplifier (17) to which the control signal from 4d) is applied;
~(20>), the output terminals (21) to (24) connected to the output terminals of these differential amplifiers (17) to (20), and the outputs of these differential amplifiers (21) to (24) It consists of a connected time constant circuit (25). (26) is a PWM
(Pulse width modulation) voltage conversion circuit, including a transistor (28) whose emitter and collector are connected to a power supply (27), a smoothing die (29) connected to the reflector of the transistor (28), and a coil. (30) and a capacitor (31), an operating voltage (VP.
A comparator (32) for comparing M) and the comparator (32)
A PWM voltage generator (33) obtains a PWM voltage by comparing the voltage from the oscilloscope with the sawtooth wave signal from the sawtooth wave oscillator (34).
〉. The PWM voltage from the F'WM voltage generator (33) is applied to the base of the transistor (28) and the operating voltage (v,wM〉) applied to the comparator (32〉).
Transistor (9〉~(12〉Noross voltage (V,.S
S> is increasing.

Next, the operation of the drive voltage generating circuit of the present invention will be explained using a CD player as an example.

If the focus of the light beam from the optical pickup shifts due to bending or the like while a CD disc is being played, that shift will appear as a change in the amount of light beam irradiated to each photodetector via the half mirror. By taking the difference between the signals generated from each of the photodetectors, a focus shift signal corresponding to the focus shift is detected. The detected focus shift signal (VCt) is applied to the input terminal (3), and the reference voltage (Vref) supplied to the input terminal (2) is applied to the absolute value amplifier (4>), and the reference voltage (Vref) is applied to the absolute value amplifier (4). Vref
) and the focus shift signal (VC.), the absolute value of the difference is amplified and the focus control signal (V v t
) is generated. On the other hand, the comparator <5> compares the magnitude of the defocus signal (VcI) and the reference voltage (Vref), generates a positive or negative operation direction indicating signal, and supplies the signal to the logic circuit (6). Ru. When the operation direction instruction signal applied to the logic circuit <6> is positive,
A signal is applied from the logic circuit (6>) to the amplifier (7) and the transistor (12) to turn on the transistor (12).On the other hand, the operational amplifier (7>) receives the focus control signal (v1) and the operation direction instruction signal. is added in a superimposed manner, and the amplified signal is applied to the transistor (9), which turns on according to the magnitude of the applied voltage, so the operating voltage (V, W,) is the same as that of the transistor (9).
9), Four Force Scoinore (13) and Transistor
12>, the focus control signal (V, t)
The objective lens is moved away from the CD disk surface according to the size of the disc.

? When the operation direction instruction signal generated from the comparator <5> is negative, the transistor (
10> and the operational amplifier (8), turning on the transistors (11) and (10), so the operating voltage (V
EM) flows through the transistor (11) to the focus coil (13) in the opposite direction to the above. Therefore, the objective lens is moved in a direction closer to the CD disk surface. Although the focus servo was described above, the tracking servo is also almost the same, and a photodetector detects the deviation of the light beam from the track on the CD disk surface, and the drive circuit (1b)
A tracking control signal (V) is obtained by applying it to the input terminal of the objective lens and taking the absolute value of the difference from the reference voltage. In addition to the coil, tracking is performed by moving the objective lens in the horizontal direction relative to the CD disk surface.When tracking control cannot be achieved only by moving the objective lens, this is detected and an input signal is applied to the drive circuit (1c>?). , a control signal (V■) is taken out, and the control signal (vMm) is applied to the pickup feed motor, which rotates the motor and moves the entire pickup in the tracking direction to perform tracking.Furthermore, the CD disc is always In order to rotate at a constant speed, a synchronization signal extracted from the information signal is added to the drive circuit (1d) to obtain a control signal (V■), and the spindle motor is controlled by the control signal (V■). The CD disc is rotated at a constant linear velocity. By the way, since the control voltage to each actuator of the CD player such as the focus coil is sufficiently small compared to the power supply voltage from the power supply (27), If the power supply voltage is directly applied to each of the drive circuits (1a) to (1d), there will be a loss and the power consumption will be large.Therefore, the maximum control signal among the control signals is detected, and the power supply voltage is applied to each of the drive circuits (1a) to (1d).
The voltage obtained by comparing the operating voltage (VP■) applied to
Said power supply with voltage? and switching the operating voltage (
VPWM) is the maximum control signal voltage. That is, the control signals <<v1> to (V■) from each of the drive circuits <1a> to (1d) are the maximum control signal detection circuit (15).
The input terminal (16a) of each differential amplifier (17) to (20)
) to (16d) and after being amplified, the diode <
21) to (24) to the time constant circuit (25). The control signals from each of the drive circuits (1a> to (1d)) vary from 0.6V to 1.2V depending on the control state of the actuator.
It changes to v. For example, when the objective lens is largely displaced from the disk surface, a large focus control signal is generated from the drive circuit (1a) in order to return the objective lens to its original position. In this way, the control signals (VMI) to (VM.) generated from each drive circuit (1a) to (1d) are changing every moment. Then, the control signals (V M t ) to (VM.
) is amplified and the die capacitor (
2l> to (24) to the time constant circuit (25>), so only the maximum control signal among the control signals is applied to the time constant circuit (25) and smoothed.The smoothed signal and operating voltage EE (Vrwm) are comparators (32)
Compared with? In the WM voltage generator (33), the sawtooth wave signal from the sawtooth oscillator (34) is PWM-converted to obtain a PWM voltage.The obtained PWM voltage is applied to the base of the transistor (28), 28
> is turned on and off intermittently, so the power supply voltage from the power supply (27) flows intermittently. The intermittent power supply voltage is smoothed by a die (29), a coil (30), and a capacitor (31), and is applied to each drive circuit (1a) to (1d) as an operating voltage (VP). Ru.

(G) Effects of the Invention As described above, the drive voltage generation circuit of the present invention detects the maximum output voltage among the output voltages generated from each drive circuit to which a common operating voltage is supplied, and PWM conversion is performed on the voltage obtained by comparing the operating voltage and the P
Since the power supply voltage is intermittent using the WM-converted PWM voltage, the operating voltage to each drive circuit is suppressed to the required level, reducing power consumption. Furthermore, since the PWM voltage conversion circuit is shared, the circuit configuration is not complicated.

[Brief explanation of the drawing]

The figure is a diagram of the drive voltage generation circuit of the present invention. (1a>～(
1d>...Drive circuit, (l5)...Maximum control signal detection circuit, (26>...PWM voltage conversion circuit.

Claims (2)

[Claims] (1) a plurality of drive circuits that supply drive voltages to the drive means according to the detection current detected by the detection means; a maximum drive voltage detection circuit that detects the maximum output voltage generated by the drive circuit; A drive voltage generation circuit comprising a PWM voltage conversion circuit that performs PWM voltage conversion of a power supply voltage supplied to each of the drive circuits using a signal based on a detected maximum output voltage. (2) A comparator that compares the detected voltage from each detection unit with a reference voltage, and is controlled by the control signal and operation signal obtained from the comparator and supplies drive current to the focus coil, tracking coil, and spindle motor, respectively. a maximum control current detection circuit that detects the maximum control signal among the control signals from each of the comparators; and a maximum control current detection circuit that detects the maximum control signal from among the control signals from the respective comparators; A drive voltage generation circuit comprising a PWM voltage conversion circuit that converts a power supply voltage supplied to each drive circuit into a PWM voltage using a signal based on a signal.