JPS59101036A - Lens driving circuit of digital audio disk player - Google Patents

Abstract

PURPOSE:To perform accurate control to return a lens by a little distance under the pose mode, by installing an adder which inputs a return pulse and forward pulse of opposite polarities and a coupling condenser which supplies the output signal of the adder to a lens driving circuit. CONSTITUTION:When a lens return controlling signal D is generated, the output signal G of an inverter 18 also becomes ''L'' and is outputted from an adder 16 as its output signal I. The output signal I of the adder 16 is outputted to the output signal of a coupling condenser 23 under almost the same conditions and the output signal K of the condenser 23 is supplied to another adder 6 through a variable resistance 24 for level adjustment. The adder 6 adds the output signal K of negative polarity to the output signal C of a loop filter 2 and outputs the added result. However, since the output signal C is composed only of a DC component because a lens servo loop is interrupted in the period when the output signal K is generated by means of a switching circuit 12, a lens driving circuit 4 executes lens returning control of about 10 seconds in accordance with the time width of the lens return controlling signal D.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a digital medium audio disc player, and more particularly to a lens drive circuit for driving a lens provided in an optical pickup in the radial direction of the disc.

BACKGROUND TECHNOLOGY A digital audio disc player plays back a disc on which digitized audio signals, synchronization signals, etc. are optically recorded at a constant linear velocity, and a high-fidelity playback signal can be obtained. It has excellent features. Then, for example, 1.6μ
Information recorded at intervals of m is read by moving an optical pickup in the radial direction of the disk. In this case, the optical pickup controls the reading position using a fine adjustment system and a coarse adjustment system. In other words,
The fine adjustment system performs tracking by driving a lens provided on the optical pickup, and the coarse adjustment system is configured to move the optical pickup by driving a pickup motor. When the tracking by the lens drive in the fine adjustment system reaches its limit, the pickup motor of the coarse adjustment system is driven to drive the optical pickup quantitatively, and the lens system that drives the lens is driven by a servo. It is made up of loops.

In this case, when searching for the desired information, it is necessary to move the lens of the optical pickup over an amount equivalent to approximately 10 seconds of reproduction, and when operating the Bose, it is necessary to move the lens over an amount equivalent to reproduction within 1 second. be.

However, there is no simple circuit that can reliably drive the lens in this manner, and a complicated and expensive circuit must be used. Further, even when such a complicated circuit is used, it is not possible to accurately move the lens over a reproduction amount within one second during a pause operation.

DISCLOSURE OF THE INVENTION Accordingly, it is an object of the present invention to provide a lens drive circuit for a digital audio disc player that can accurately move a lens provided in an optical pickup by a desired amount.

Another object of the present invention is to provide a lens drive circuit for a digital audio disc player that can accurately control the lens back by a small amount when in Bose mode.

In order to achieve such an object, the present invention includes an adder circuit that inputs return pulses and send pulses of opposite polarity, and an output signal of this adder circuit that is connected to a lens and drive circuit provided in a lens servo loop. It consists of a coupling capacitor to be supplied, and a switch circuit connected through a resistor between the output side of this coupling capacitor and ground, and turned on by a Bose mode signal to load the coupling capacitor. It is.

Launch F8! DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a circuit diagram showing an embodiment of a lens driving circuit of a Digimol audio disc player according to the present invention. In the figure, a radial error detection circuit receives a pickup signal A supplied from an optical pickup (not shown) as an input and generates an output signal B corresponding to the amount of tracking deviation. A loop filter which receives the generated output signal B as an input; 4 is a lens driving circuit; and by inputting the output signal 0 of the loop filter 2 through a variable resistance path 5 and a second addition circuit 6, this input signal is The radial coil 7 is driven in accordance with the signal to control tracking of a lens (not shown) provided in the optical pickup. These circuits constitute a lens servo loop. Reference numeral 8 denotes a pulse detection circuit which inputs a negative polarity lens return control signal supplied from a microcomputer (not shown) and a lens advance control signal E, and is constituted by a Nandt gate 8a. Reference numeral 9 denotes an integrating circuit having fast attack/slow release characteristics that receives the output signal F of the pulse detection circuit 8 as an input, and is constituted by a diode 10 and a capacitor 11 for preventing backflow. 12 is the integration circuit 9
A first switch circuit operates when an output is generated and connects the input side of the loop filter 2 to ground to interrupt the lens servo loop, and includes a transistor 13 and a resistor 14.1.
5. Reference numeral 16 designates a first adder circuit, which includes inverters 17 and 18 that pass the lens return control signal and send out a return pulse G of negative polarity, and an inverter 17 and 18 that invert the lens return control signal E and send out a return pulse H of positive polarity. The inverter 19 that generates the return pulse G and the sending pulse H
and mixing resistors 20 to 22 for synthesizing and outputting. 23 is a coupling capacitor that supplies the output signal of the adder circuit 16 to the adder circuit 6 provided on the input side of the lens drive circuit 4 via a variable resistor 24; 25 is a link between the output side of the coupling capacitor 23 and the ground; A second switch circuit is connected to the second switch circuit via a resistor 26, and is turned on when the Bose mode signal J is generated. This switch circuit 25 includes a transistor 26
and resistors 27 and 28.

In the circuit configured in this way, the amount of deviation in the radial direction is detected in the radial error detection circuit 1 by processing a pickup signal supplied from an optical pickup (not shown) during normal times, and this deviation is detected by the radial error detection circuit 1. An output signal B corresponding to the amount is output. Then, this output signal B is supplied to the loop filter 2 via the resistor 3, so that only the reduced amount is outputted to the output signal C by the integration operation.
is extracted as. The output signal C extracted in this way is connected to a level-adjusting variable resistor 5 and an adder circuit 6.
The signal is supplied to the lens drive circuit 4 via. The lens drive circuit 4 controls the position of the lens of an optical pickup (not shown) by applying foot noise control in the radial direction of the disk by driving the radial coil 7 in accordance with an input signal.

Next, from a microcomputer (not shown),
When the negative polarity lens return control signal shown in a) is supplied, the pulse detection circuit 8 generates an output signal F shown in FIG. In this case, when the integrator circuit 9 is supplied with the output signal F, the diode 10
The capacitor 11 is rapidly charged via the capacitor 11, and the output rises.

When the supply of this output signal F is cut off, the return discharge of the capacitor 11 is blocked by the diode 10, so that the discharge time constant increases and a signal with an extended trailing edge of the input signal is generated, causing the switch to switch. is supplied to circuit 12.

Therefore, this switch circuit 12 is also turned on for a period whose trailing edge is longer than the period during which the output signal F1 of the pulse detection circuit 8, that is, the lens return control signal, is generated. When this switch circuit 12 is turned on, that is, when the transistor 13 is turned on, the input side of the loop filter 20 is grounded, so that an output signal B for lens tracking control is output from the radial error detection circuit 1. is dropped and the lens servo loop is cut off.

On the other hand, when the lens return control signal is generated, the output signal G of the inverter 18 also becomes %L as shown in FIG. 2(e).
tt, and this output signal G is output from the adder circuit 16 as an output signal. In this case, since the switch circuit 25 is off, the load on the coupling capacitor 23 becomes extremely small. As a result, the coupling capacitor 23
As shown in FIG. 2(g), the output signal of
The output signal I of No. 6 is output in almost the same form, and this output signal K is connected to the variable resistor 24 for level adjustment.
is supplied to the adder circuit 6 via. The adder circuit 6 adds the negative output signal K to the output signal 0 of the loop filter 2 and outputs the result. However, during the period in which this output signal is generated, the lens servo loop is cut off by the switch circuit 12, so the output signal 0 is only the direct component, and the lens drive circuit 4 receives the lens return control signal. For example, the return control is executed for about 10 seconds depending on the time width of the return.

Next, as shown in FIG. 3(b), the lens feed control signal E
is generated, the pulse detection circuit 8, the integration circuit 9, and the switch circuit 12 operate in the same manner as in the case described above to cut off the lens servo loop. On the other hand, the inverter 19 of the addition circuit 16 sends a positive polarity signal. A pulse H is generated as shown in FIG. 3(f). Then, the adder circuit 16 outputs an output 1 symbol corresponding to the sending pulse H, and this output signal is sent out as an output signal via the coupling capacitor 23 as shown in FIG. 3(y). . The output signal generated in this way is supplied to the lens drive circuit 4 via the addition circuit 6, so that the return control of the lens is performed in the same manner as in the case described above.

Next, when the Bose mode signal J is generated as shown in FIG. 4(c), the transistor 26 is turned on and the output side of the coupling capacitor 23 is connected to the resistor 27. The load on the coupling capacitor 23 increases accordingly. In this state, when a lens return control signal is supplied from a microcomputer (not shown) at predetermined intervals as shown in FIG. 4(a), the output signal of the inverter 18 as shown in FIG. 4(e) is G will be sent out from the adder circuit 16 as an output signal. This output signal (■) is supplied to the adder circuit 6 via the coupling capacitor 23, and is differentiated due to the increase in load on the coupling capacitor 23 due to the on-operation of the switch circuit 250 and the operation of the resistor 16. It will act as a circuit. Therefore, the coupling capacitor 2 is connected to the output signal supplied to the adder circuit 6.
3 is differentiated as shown in FIG. 4(g).

In this case, since the output signal is a bipolar differential signal, the lens is returned during the first negative differential signal portion, and a feeding action is applied to the lens during the next positive differential signal portion. This acts as a brake on the return movement of the lens. Tsu-! In the Bose mode, the lens drive circuit 4 kicks the lens in the return direction and then applies a brake to stop the lens, so the lens moves within 1 second, which is necessary for pausing. And in this case,
Since the movement of the lens is stopped by applying braking, the amount of movement is always constant.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing one embodiment of a lens drive circuit for a digital audio disc player according to the present invention, and FIG.
Figures (a) to (h), Figures 3 (a) to (h), and Figures 4 (a) to (h) are operation waveform diagrams of each part of the circuit shown in Figure 1. DESCRIPTION OF SYMBOLS 1... Radial error detection circuit, 2... Loop filter, 4... Lens drive circuit, 6... Second addition circuit, 7... Radial coil, 8... Pulse detection circuit,
9... Integrating circuit, 16... First addition circuit, 25...
・Switch circuit, 23...coupling capacitor,
29...Resistance.

Claims (1)

[Claims] (1) A first adder circuit that inputs a lens return control signal and a lens feed control signal and sends out either a return pulse or a feed pulse of opposite polarity, and the output signal of this adder circuit is provided in a lens two-way loop. A coupling capacitor is connected via a resistor between the output side of the coupling capacitor and the ground, and is turned on by the Bose mode signal to 1. A lens drive circuit for a digital audio disc player, comprising a switch circuit for increasing the load on a coupling capacitor.