JP2003133635A - Semiconductor laser apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor laser apparatus that can securely prevent break of a laser diode due to static electricity, and the damage to an internal circuit due to overcurrent. SOLUTION: In the semiconductor laser apparatus, the cathode side of a laser diode 11 where the laser diode 11 is connected to a drive circuit 12 in series is grounded. A control voltage for controlling the laser diode 11 is applied from a terminal 14 of the drive circuit 12. A terminal 15 is connected to a switch control circuit 13 for controlling the ON/OFF of switches 16 and 17. The switch 16 is connected to both ends of the laser diode 11 in parallel. The switch 17 is connected between the laser diode 11 and the drive circuit 12 in series. When power is turned on, the switch 17 is turned on after the switch 16 is turned off.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device, and more particularly to a semiconductor laser device as a light source which constitutes an optical pickup in an optical disk device such as a CD player and a CD-RW drive.

[0002]

2. Description of the Related Art Conventionally, a semiconductor laser device has been used as a light source forming an optical pickup in an optical disk device such as a CD player or a CD-RW drive.
A laser diode is used in this semiconductor laser device, but the laser diode is easily destroyed by static electricity.

Therefore, various measures have been taken to prevent electrostatic breakdown when the laser diode is not operated, such as when the product is distributed in a factory. next,
An example is shown below.

FIG. 2 is a circuit diagram showing a conventional semiconductor laser device. FIG. 2A shows an example of a cathode common,
(B) shows an example of the anode common.

The laser diode 21 is a drive circuit 22.
Controlled by. A control voltage is applied from the terminal 24 of the drive circuit 22, and an enable signal is applied from the terminal 25.

In the example of FIG. 2A, the laser diode 2
Short lands 23, 23 for short-circuiting the both ends are provided at both ends of each 1. The cathode side of the laser diode 21 is grounded. On the other hand, in the example of FIG. 2 (B), the cathode side is not grounded, and the anode is connected to the positive power source.
The semiconductor laser device of FIG.

In any of the semiconductor laser devices, the short lands 23, 23 are soldered to establish a short circuit between the anode and the cathode of the laser diode 21. In addition, instead of soldering the short lands 23, 23, there is an example in which the short lands 23, 23 are connected by a metal fitting for short-circuiting to make a short circuit between the anode and the cathode.

Such short-circuiting of the short land is performed at the shipping stage of the manufacturing process of the optical pickup, and thereafter the optical pickup is distributed and incorporated into a CD player, a CD-RW drive or the like.

[0009]

However, when the optical pickup is incorporated into a CD player, a CD-RW drive or the like, it is necessary to remove the solder or the metal fitting that short-circuits the short land, which is troublesome. Therefore, there is a problem in work efficiency.

Further, when the short land is short-circuited with solder, the laser diode may be deteriorated by the heat at the time of soldering and removing the solder. Also,
When using the metal fitting for short circuit, there is a problem of recycling the metal fitting.

In addition, since the both ends of the laser diode are not short-circuited in the process after the optical pickup is incorporated in a CD player or the like, there is a problem that electrostatic damage that may occur in the laser diode cannot be prevented.

Further, if the solder or the metal fittings are forgotten to be removed, an excessive current may flow through the short-circuited drive circuit 22, which may damage the drive circuit 22.

An object of the present invention is to provide a semiconductor laser device capable of reliably preventing damage to a laser diode due to static electricity and damage to an internal circuit due to overcurrent.

[0014]

In order to achieve the above object, a semiconductor laser device according to claim 1 is a semiconductor laser device including a laser diode and a drive circuit for driving the laser diode. A first switch connected in parallel to both ends of the laser diode for short-circuiting the laser diode, and a second switch connected in series between the laser diode and the drive circuit,
A switch control circuit is provided to control so that when one of the first switch and the second switch is OFF, the other is ON.

According to another aspect of the semiconductor laser device of the present invention, when the first switch is ON and the second switch is OFF under the control of the switch circuit, the laser diode is short-circuited while the drive circuit is Not short circuited. As a result, electrostatic damage to the laser diode can be prevented and damage to the drive circuit due to overcurrent can be prevented.

A semiconductor laser device according to a second aspect is the semiconductor laser device according to the first aspect, wherein the switch control circuit turns off the second switch before shorting the laser diode. 2. The semiconductor laser according to claim 1, wherein when the first switch is turned on and the short-circuited laser diode is opened, the first switch is turned off and then the second switch is turned on. apparatus.

According to the semiconductor laser device of the second aspect, when the laser diode is short-circuited, the second switch is turned off and then the first switch is turned on, and when the short-circuited laser diode is opened. Since the first switch is turned off and then the second switch is turned on, electrostatic damage to the laser diode and damage to the drive circuit due to overcurrent can be reliably prevented.

A semiconductor laser device according to a third aspect is the semiconductor laser device according to the second aspect, wherein the switch control circuit operates according to ON / OFF of a power source of the drive circuit.

According to another aspect of the semiconductor laser device of the present invention, the switch control circuit turns on / off the power source of the drive circuit.
Since it operates according to F, the first switch is turned off and then the second switch is turned on when the power supply of the drive circuit is on, so that the drive circuit is more reliably prevented from being damaged due to overcurrent. it can.

A semiconductor laser device according to a fourth aspect is the semiconductor laser device according to the second aspect, wherein the switch control circuit is responsive to a drive circuit control signal applied to the drive circuit for controlling the drive circuit. It is characterized by working.

According to another aspect of the semiconductor laser device of the present invention, the switch control circuit operates in response to a drive circuit control signal for controlling the drive circuit, which is applied to the drive circuit. The destruction of the circuit can be prevented more reliably.

A semiconductor laser device according to a fifth aspect is the semiconductor laser device according to the fourth aspect, wherein the switch control circuit turns on the first switch when the drive circuit control signal is disabled. It is characterized by doing.

A semiconductor laser device according to a sixth aspect is the semiconductor laser device according to any one of the first to fifth aspects, wherein the drive circuit, the first switch and the second switch, and a switch control circuit. Are configured in the same IC.

According to the semiconductor laser device of the sixth aspect, since the drive circuit, the first switch and the second switch, and the switch control circuit are formed in the IC,
The semiconductor laser device can be miniaturized.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a semiconductor laser device according to an embodiment of the present invention will be described in detail.

FIG. 1 is a circuit diagram showing an example of a semiconductor laser device according to an embodiment of the present invention. (A) shows an example of a cathode common, and (B) shows an example of an anode common.

In FIG. 1A, the laser diode 1
1 is connected in series to the drive circuit 12 (drive circuit). The cathode side of the laser diode 11 is grounded. A control voltage for controlling the laser diode 11 is applied to the terminal 14 of the drive circuit 12. The drive circuit 12 drives the laser diode 11 according to the applied control voltage. A switch control circuit 13 for controlling ON / OFF of two switches described below is provided at the terminal 15.
Are connected. The enable signal input to the terminal 15 also switches enable / disable of the drive circuit 12. The enable signal may be changed from disable to enable when the power of the device in which the semiconductor laser device is mounted is turned on, or the enable signal may be enabled from disable immediately before the driving of the laser diode is started. It may be changed to. The change from enable to disable is similar.

One of the two switches controlled by the switch control circuit 13 is a switch 16 (first switch) which is connected in parallel to both ends of the laser diode 11 and short-circuits the laser diode 11. . Another switch controlled by the switch control circuit 13 is a switch 17 (second switch) connected in series between the laser diode 11 and the drive circuit 12. The control voltage input to the terminal 14 and the enable signal input to the terminal 15 are generated by a control circuit (not shown).
The control circuit (not shown) controls the operation of the entire device (CD player or the like) in which the semiconductor laser device is mounted.

(A) shows a state in which the drive circuit 12 is disabled, and the laser diode 11 is short-circuited because the switch 16 is ON. On the other hand, since the switch 17 is off, the drive circuit 12
Is not short-circuited. Therefore, the laser diode 11 is not destroyed even if static electricity is generated.

When the terminal 15 is enabled, the switch control circuit 13 controls so that the switch 16 is turned off and then the switch 17 is turned on. As a result, the drive circuit 12 is not directly connected to the ground or the positive power supply when the power is turned on, so that an excessive current does not flow to the short-circuited drive circuit 22 and the drive circuit 22 is prevented from being damaged by the excessive current. When turning off the power,
The switch control circuit 13 controls so that the switch 16 is turned on after the switch 17 is turned off.

When the drive circuit 12 starts and ends the circuit operation by the enable signal applied from the terminal 15, the switch 17 is turned off when it is disabled.
After setting to F, the switch 16 is turned on. in this way,
Since there is no period in which both the switches 16 and 17 are simultaneously turned on, destruction of the laser diode 11 and the drive circuit 22 is better prevented.

Although the switches 16 and 17 are transistor switches, they may be mechanical switches. Switch 1
When 6, 17 are transistors, the switch 16,
17, the drive circuit 12, and the switch control circuit 13 can be configured in the same IC.

In this way, the semiconductor laser device can reliably prevent electrostatic damage to the internal laser diode 11 and drive circuit 12.

FIG. 1B shows a modification of the semiconductor laser device shown in FIG. 1A, in which a switch 18 (first switch) for short-circuiting the laser diode 11 is a laser diode. A switch 19 (second switch) is connected in series between the laser diode 11 and the drive circuit 12 and is connected in parallel to both ends of the laser diode 11. The semiconductor laser device shown in FIG. 1A is different in that the cathode side of the laser diode 11 and the switch 18 are not grounded and are connected to a positive power source.

Also in the semiconductor laser device having such a structure, it is possible to surely prevent the built-in laser diode 11 and drive circuit 12 from being electrostatically damaged, as in the above case.

Further, since none of the semiconductor laser devices described above uses solder for short-circuiting the laser diode 11, there is no deterioration of the laser diode due to heat generated during soldering and removal of the solder. Also, not using solder is clean from the environmental point of view.

Further, since no metal fitting is used for short-circuiting the laser diode 11, there is no need to recycle the metal fitting, which is suitable for distribution.

Furthermore, there is no need for soldering, solder removal, fitting or removal of metal fittings, and the laser diode 11 is short-circuited and the short-circuited laser diode 11 is opened only by turning the switch ON / OFF as necessary. This is advantageous in terms of work efficiency because it can be performed easily.

The above semiconductor laser device can be used not only as an optical pickup for a CD player or a CD-RW drive, but also as a laser diode drive module for communication equipment or medical equipment.

[0040]

As described in detail above, according to the semiconductor laser device of the first aspect, the laser diode is controlled by the switch circuit because the second switch is off when the first switch is on. Is shorted while the drive circuit is not. As a result, electrostatic damage to the laser diode can be prevented and damage to the drive circuit due to overcurrent can be prevented.

According to the semiconductor laser device of the second aspect, when the laser diode is short-circuited, the second switch is turned off and then the first switch is turned on, and the short-circuited laser diode is opened. Since the first switch is turned off and the second switch is turned on, electrostatic damage to the laser diode and damage to the drive circuit due to overcurrent can be reliably prevented.

According to another aspect of the semiconductor laser device of the present invention, the switch control circuit turns on / off the power source of the drive circuit.
Since it operates according to F, the first switch is turned off and then the second switch is turned on when the power supply of the drive circuit is on, so that the drive circuit is more reliably prevented from being damaged due to overcurrent. it can.

According to another aspect of the semiconductor laser device of the present invention, the switch control circuit operates according to a drive circuit control signal for controlling the drive circuit, which is applied to the drive circuit. The destruction of the circuit can be prevented more reliably.

According to the semiconductor laser device of the sixth aspect, since the drive circuit, the first switch and the second switch, and the switch control circuit are formed in the IC,
The semiconductor laser device can be miniaturized.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an example of a semiconductor laser device according to an embodiment of the present invention, (A) shows an example of a cathode common, and (B) shows an example of an anode common.

FIG. 2 is a circuit diagram showing a conventional semiconductor laser device, in which (A) shows an example of a cathode common and (B) shows an example of an anode common.

[Explanation of symbols]

11 Laser diode 12 drive circuit 13 Switch control circuit 14,15 Drive circuit 12 terminals 16, 18 switch (first switch) 17,19 switch (second switch)

Claims (6)

[Claims] 1. A semiconductor laser device comprising a laser diode and a drive circuit for driving the laser diode, comprising: a first switch connected in parallel to both ends of the laser diode for short-circuiting the laser diode; A second switch connected in series between the laser diode and the drive circuit; and a switch for controlling one of the first switch and the second switch to be on when the other is off. A semiconductor laser device comprising: a control circuit. 2. The switch control circuit turns off the second switch when the laser diode is short-circuited.
When the first switch is set to F and then the first switch is turned on to open the short-circuited laser diode, the first switch is turned off and then the second switch is turned on.
The semiconductor laser device according to claim 1, wherein 3. The semiconductor laser device according to claim 2, wherein the switch control circuit operates according to ON / OFF of a power source of the drive circuit. 4. The semiconductor laser device according to claim 2, wherein the switch control circuit operates in response to a drive circuit control signal applied to the drive circuit for controlling the drive circuit. 5. The semiconductor laser device according to claim 4, wherein the switch control circuit turns on the first switch when the drive circuit control signal is disabled. 6. The drive circuit, the first switch and the second switch, and the switch control circuit are the same I.
The device according to claim 1, which is configured in C.
6. The semiconductor laser device according to any one of items 1 to 5.