JPS639032A - Controller for optical information reproducing device - Google Patents

Abstract

PURPOSE:To prevent a control element from being damaged and to obtain a highly reliable device by detecting the abnormality of a power supply and stopping the operation of a circuit for driving the control element to interrupt the inflow of overcurrent into the element. CONSTITUTION:When abnormality is generated in power supply voltage and the voltage of the power supply 14b/14a is disconnected, a transistor (TR) 31/32 in a detecting circuit 15 is turned on/off, an output (a) is turned to the low level and an output (b) is turned to the high level, turned to the low level by an inverter 34 and then inputted to an AND gate 33. Thereby, the output of the circuit 15 is inputted to a protector circuit 16 as the low level in either case, the TR 35/36 is turned off/on, on the output of the circuit 16 is turned to the low level, and a current source circuit in a driving circuit 12 is interrupted, so that the inflow of overcurrent into the control element 13 is interrupted and the element 13 can be prevented from being damaged.

Description

[Detailed description of the invention] Industrial applications The present invention relates to an optical information reproducing device.

2. Description of the Related Art As a conventional control device for an optical information reproducing device, there is, for example, a tracking control device as disclosed in Japanese Patent Application Laid-open No. 153562/1983. This will be explained below using FIG. 3.

A light beam generated from a light source 1 such as a semiconductor laser is collimated by a coupling lens 2, reflected by a polarizing beam splitter 3, passes through a λ/4 plate 4 (λ is the wavelength of the light beam), and is focused. After being focused by a lens 5, it is irradiated onto a disk 7 which is being rotated by a motor 6. The reflected light beam from the disk passes through the converging lens 5, the λ/4 plate 4 again, the polarizing beam splitter 3, and is irradiated onto the photodetector 8 having a two-split structure.

The direction of the dividing line of the photodetector 8 having a two-part structure is set to coincide with the tangential direction of the concentric (or spiral) track on the disk T onto which the light beam is irradiated in a predetermined focused state.

The output B of the photodetector 8 is the output of each preamplifier 91.
After being amplified by L and 9b, it is input to a differential amplifier 10, and the differential amplifier 10 outputs both preamplifiers 92L.

9b is obtained, and this signal is input to the tracking control element 13 via a phase compensation circuit 11 for compensating the phase of the tracking control system and a drive circuit 12 for power amplification. . Therefore, the tracking control element 13 is controlled so that the light beam on the disk 7 correctly scans the track.

The preamplifiers ga and gb, the differential amplifier 10, the phase compensation circuit 11 and the drive circuit 12 are bipolar (power supply voltage Vcc
) is operated by the power supplies 14&, 14b.

Problems to be Solved by the Invention In conventional control devices, if one of the two bipolar power supplies that operate the control device drops or cuts out due to a failure of the device, etc. A problem has arisen in that the drive voltage of the drive circuit changes, causing an overcurrent to flow through the control element and damaging the control element.

The present invention has been made in view of the above problems, and detects when an abnormality occurs in the power supply voltage and stops the operation of the drive circuit to prevent overcurrent from flowing to the control element. The object of the present invention is to prevent damage to control elements and provide a highly reliable device.

Means for Solving the Problems The present invention provides a focusing means for focusing a light beam generated from a light source, a detection means for detecting a signal according to the positional relationship between the light beam and a track on a record carrier, and the focusing means. a moving means for moving a light beam focused by a light beam in a direction substantially perpendicular to the track direction of the record carrier; a driving means for driving the moving means in response to a signal from the detecting means; and a signal from the detecting means. tracking control means for controlling the light beam on the record carrier to always scan the track by transmitting the information to the driving means, operating the driving means, and driving the moving means; the detecting means; the moving means; A power supply abnormal state detection means for detecting an abnormal state of a power supply for operating the drive means and the tracking control means, and a protection means for disabling the drive means, and in response to a signal from the power supply abnormality state detection means, The protection means is configured to operate.

Effect of the present invention With the above-described configuration, when an abnormality occurs in the power supply supplied to the device, it is detected and the operation of the drive circuit is stopped, so that no overcurrent flows to the control element, and the control element damage to the equipment can be prevented, and the reliability and maintainability of the equipment can be improved.

Example Embodiments of the present invention will be described in detail using the drawings.

FIG. 1 is a block diagram showing the configuration of a tracking control device according to an embodiment of the present invention. The same parts as in the conventional tracking control device are given the same numbers, and the explanation thereof will be omitted.

When an abnormality occurs in the power supply 1jLL or 14b, the power supply abnormality detection circuit 15 detects this and activates the protection circuit 1.
The information about this power supply abnormality is transmitted to 6.

The protect circuit 16 cuts off the current source circuit of the drive circuit 12 and stops the operation of the tracking control element 13.

FIG. 2 is a detailed diagram showing one embodiment of the power supply abnormality detection circuit 16 and the protection circuit 16.

This embodiment will be described in more detail with reference to FIG.

Power supply voltage of this control device +v0°, -vo. In a normal state, the transistor 31 is in an off state with no pace current flowing through it, the transistor 32 is in an on state through a pace current, the collector of the transistor 31, that is, the output a is at a HIGH level, and the collector or output a of the transistor 32 is at a low level.
It becomes OW level.

Since this output ab is directly inputted to the ND gate 33Vc, and the output is inputted to the AND gate 33 via the inverter 34, the output of the AND gate 33 becomes HIGH level.

The output of this person ND gate 33 is the power supply abnormality detection circuit 15
It is input to the protect circuit 16 as an output.

When the output of the power supply abnormality detection circuit 15 is at HIGH level and is input to the protection circuit 16, the transistor 35
is in the on state, the transistor 36 is in the off state, and the collector of the transistor 36, that is, the output C is HI
(1, H level, and is input to the drive circuit 12 as the output of the protect circuit 16. When this input is at the HIGH level, the drive circuit 12 becomes operational, and current flows through the control element 13 to drive it. .

A case where an abnormality occurs in the power supply voltage of this control device will be explained. When the voltage -VCC of the power supply 14b is cut off, the base current flows to the transistor 31, the transistor 31 is turned on, the output a becomes Lot level, and the AND
The signal is input to gate 33. Therefore AND gate 33
That is, the output of the power supply voltage detection circuit 15 is related to the level of the output voltage (if it is not Lot level, it is input to the protect circuit 16, the transistor 36 is off, and the transistor 3θ is in the on state). The output becomes Lot level and is input to the drive circuit 12.

At this time, the current source circuit of the drive circuit 12 is cut off and no current flows through the control element 13. Therefore, the operation of the control element 13 is stopped.

When the voltage v0° of the power supply 14& is cut off, the transistor 3
No base current flows through the transistor 2, the transistor 32 is turned off, the output becomes HIGH level, and is input to the inverter 34. The output of the inverter 34 becomes LOW level and is input to the AND gate 33. Therefore, the output of the ND gate 33, that is, the power supply voltage detection circuit 16
The output of is related to the level of output & (Lo! level, and is input to the protection circuit 16, the transistor 35 is turned off and the transistor 36 is turned on, and the output of the protection circuit 16 is Lot level, which is input to the drive circuit 12. Therefore, no current flows through the control element 13.

As explained above, according to the power supply abnormality detection circuit 15 and the protection circuit 16, the power supply voltage +VCC or -VCC used in the present control device can be detected with a simple configuration.
If an abnormality occurs, it can be detected immediately and the information can be transmitted to the drive circuit 12.

Therefore, if this embodiment is used, when an abnormality occurs in the power supply 14a or 14b supplied to the control device, it is detected, the operation of the circuit that drives the control element is stopped, and the control element is It is possible to prevent overcurrent from flowing. Therefore, even if one of the bipolar power sources drops in voltage or is cut off due to a failure of the conventional device, no overcurrent will flow to the control element, and damage to the control element can be prevented.

Further, this embodiment can be applied not only to a tracking control device but also to a focus control device in exactly the same way. Furthermore, by inputting the output of the protect circuit 16 to both the drive circuit of the tracking control element and the drive circuit of the focus control element, the above-mentioned effects can be further enhanced.

As described in detail, according to the present invention, it is possible to protect the control element from an abnormal state of the power supply voltage supplied to the control device, prevent damage to the control element, and improve reliability. We can provide expensive equipment.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of a tracking control device that is an embodiment of the present invention, Fig. 2 is a detailed diagram of the power abnormality detection circuit and protection circuit of Fig. 1, and Fig. 3 is a conventional tracking control device. FIG. 2 is a block diagram showing the configuration of the device. 1... Semiconductor laser, 2... Coupling lens, 3... Polarizing beam splitter, 4
.....lambda./4 plate, 5 ..... focusing lens, 6
...Motor, 7...Disc, 8...
...Photodetector, ga, gb ...preamplifier, 1o ...differential amplifier, 11 ...phase compensation circuit, 12 ...drive circuit , 13...
・Control element, 141L, 1 ab...Power supply, 15...Power supply abnormality detection circuit, 16...
・Protect circuit, 31・Old...transistor, 32・
...transistor, 33...kawa-mund gate,
34... Inverter, 35... Self... Transistor, 36... Old... Transistor. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure/A

Claims (2)

[Claims] (1) A focusing means for focusing a light beam generated from a light source, a detection means for detecting a signal according to the positional relationship between the light beam and the track on the record carrier, and recording the light beam focused by the focusing means. a moving means for moving the carrier in a direction substantially perpendicular to the direction of the track; a driving means for driving the moving means in response to a signal from the detecting means; and a driving means for transmitting the signal from the detecting means to the driving means to cause the carrier to move. tracking control means for driving the means so that the light beam on the record carrier always scans over the track; and the detection means;
The power supply abnormal state detection means includes power supply abnormal state detection means for detecting an abnormal state of a power supply for operating the moving means, the driving means, and the tracking control means, and a protection means for disabling the driving means. 1. A control device for an optical information reproducing device, characterized in that the protection means is operated in response to a signal from the optical information reproducing device. (2) A focusing means for focusing a light beam generated from a light source, a detection means for detecting a signal according to the focused state of the light beam on the record carrier, and a light beam focused by the focusing means on the surface of the record carrier. a driving means for driving the moving means in response to a signal from the moving means and the detecting means; and a driving means for transmitting a signal from the detecting means to the driving means to operate the driving means; An abnormality in the focus control means that drives the moving means to control the light beam on the record carrier so that it is always in a predetermined focused state, and the power supply that operates the detection means, the moving means, the driving means, and the focus control means. An optical device comprising power abnormality state detection means for detecting a state, and protection means for disabling the drive means, and operating the protection means in response to a signal from the power power abnormality state detection means. A control device for the expression information reproducing device.