JPH03116552A - Optical disk device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an optical disc device for recording and reproducing information on and from an optical recording medium such as an optical disc.

(Prior Art) Conventionally, in an optical disk device that optically records or reproduces information on an optical recording medium such as a write-once or erasable optical disk, a relatively small continuous beam of light is emitted from a semiconductor laser as a light source. While the information on the optical disk is read by the output, the information is recorded on the optical disk by the optical output which intermittently changes at a relatively large predetermined value or more.

Information recording in such an optical disk device is performed by the fourth
This is performed using a recording/reproducing circuit as shown in the figure. That is, one terminal of the semiconductor laser oscillator 5 that emits laser light is connected to the power supply V, and the other terminal is driven by the transistors Tr4 and T5. The collector is connected to the semiconductor laser oscillator 5, and the emitter is grounded via a resistor R3.The base is supplied with a control signal from a laser reproduction light control circuit 51. It looks like this.Photodetector 1
3 is housed in the same package 50 as the semiconductor laser oscillator 5, and photoelectrically converts the monitor light generated by the semiconductor laser oscillator 5, and the signal S5 converted into an electric signal is supplied to the laser reproduction light control circuit 51. . The laser reproduction light control circuit 51 generates a control signal according to the magnitude of the signal S5, and this signal is supplied to the base of the transistor Tr4. This forms a feedback loop, and controls the semiconductor laser oscillator 5 to emit light at a constant, weak intensity.

The transistor Tr5 generates a laser beam of high intensity during recording, and has a collector connected to the semiconductor laser oscillator 5 and an emitter grounded via a resistor R4. In addition, the base includes a recording power reference voltage generation circuit 6.
A predetermined voltage for recording is supplied from zero. The base of the transistor Tr5 is connected to the collector of the transistor Tr6, and the emitter of the transistor Tr6 is grounded. A recording pulse width setting circuit 6 is connected to the base of this transistor Tr6.
The signal output by No. 1 is supplied. The recording pulse width setting circuit 61 receives a recording pulse signal SIO corresponding to recording information, adjusts each pulse width of the recording pulse signal SIO to a predetermined width, and outputs the adjusted pulse width. The transistor Tr6 is turned on/off in accordance with the pulse signal outputted by the recording pulse width setting circuit 61, thereby turning on/off the transistor Tr5, and the semiconductor laser oscillator 5 is activated by superimposing the collectors of the transistors Tr4 and Tr5. The device is driven by a signal generated by the optical disc, and emits intermittent laser light of high intensity, thereby recording information on the optical disc.

FIG. 5 shows how the semiconductor laser oscillator 5 is mounted in the recording/reproducing circuit as described above. The semiconductor laser oscillator 5 and the photodetector 13 are housed in a package 50, and the package 50 is further supported by a metal member 70 having a heat dissipation function. The package 50 itself serves as an electrode, and the power supply voltage V
is being supplied. Therefore, in order to attach the semiconductor laser oscillator 5 to the grounded optical head 4, it is necessary to insulate the metal member 70 and the optical head 4 with the insulating member 71 and fix them using the insulating screws 72. there were.

However, in the structure insulating with the insulating member 71, the semiconductor laser oscillator 5 and the optical head 4 may be damaged due to environmental changes.
This has the drawback that precise control of laser beam irradiation cannot be performed.

(Problems to be Solved by the Invention) As described above, the present invention supplies a positive voltage using the semiconductor laser oscillator package as an electrode, and insulates the semiconductor laser oscillator and the optical head with an insulating member. This was done to eliminate the drawback that precise laser beam irradiation control is not possible due to misalignment between the semiconductor laser oscillator and the optical head due to environmental changes.By grounding the semiconductor laser oscillator package, the semiconductor laser It is an object of the present invention to provide an optical disk device that does not require insulation between an oscillator and an optical head, and therefore does not cause misalignment between a semiconductor laser oscillator and an optical head, and can precisely control laser light irradiation. purpose.

[Structure of the Invention] (Means for Solving the Problems) The optical disk device of the present invention includes a light output means for emitting a light beam, and one side of the light output means is grounded and the other side is driven to generate reproduced light. a first driving means for emitting recording light; and a second driving means for driving the other side of the light outputting means to emit recording light.
It is characterized by comprising a driving means.

(Function) The present invention performs reproduction by grounding one side terminal of the light output means and driving the other side terminal with the first driving means to emit reproduction light, and also performs reproduction by emitting reproduction light. Recording is performed by driving the recording light with a second driving means and emitting recording light by superimposing it on the drive signal of the first driving means. As a result, the terminal on one side of the light output means is grounded, so there is no need to insulate between the light output means and the optical head using an insulating member, and therefore, misalignment may occur between the light output means and the optical head. This enables precise laser beam irradiation control.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. Note that parts equivalent to those described in the conventional example will be described with the same reference numerals.

FIG. 3 shows a schematic configuration of an optical disc device as an information recording device of the present invention. In the figure, an optical disk 1 is formed by coating a metal film layer of tellurium, or bismuth, or the like in a donut shape on the surface of a circularly molded substrate made of, for example, glass or plastic.

The first disk 1 is rotated by a spindle motor 2. This spindle motor 2 is
A motor control circuit (not shown) that operates in response to a control signal from the control circuit 3 controls the start and stop of rotation, the number of rotations, and the like.

The control circuit 3 is composed of, for example, a microcomputer, and in addition to controlling the rotation of the spindle motor 2,
Controls various controls described below.

An optical head 4 is disposed below the optical disc 1 . This optical head 4 records or reproduces information on the optical disc 1, and includes a semiconductor laser oscillator 5, a collimator lens 6, and a polarizing beam splitter 7.
, objective lens 8, cylindrical lens 9 and convex lens 1
The astigmatism optical system includes a well-known astigmatism optical system 11, a 4-split photodetector 12, a photodetector 13, and the like. The optical head 4 is moved in the radial direction of the first disk 10 by a moving mechanism including a linear motor (not shown) or the like. Then, according to a control signal from the control section 3, the recording or reproducing device is moved to a target track to be recorded or reproduced.

The semiconductor laser oscillator 5 generates a diverging laser beam (light beam) according to the drive signal S1 from the optical output control circuit 14, and transmits information to the recording film 1 of the optical disc 1.
When recording on the optical disc 1, a strong laser beam whose light intensity is modulated according to the information to be recorded is generated, and when information is read and reproduced from the recording film 1a of the optical disc 1, the laser beam has a constant light intensity. It is designed to generate weak laser light.

The diverging laser beam generated by the semiconductor laser oscillator 5 is converted into a parallel beam by a collimator lens 6 and guided to a polarizing beam splitter 7. The laser beam guided by the polarized beam splitter passes through the polarized beam splitter 7 and enters the objective lens 8, and is focused by the objective lens 8 toward the recording film 1a of the optical disc 1.

The objective lens 8 is supported movably in the direction of its optical axis by a lens actuator 15 as a lens drive mechanism. The focused laser beam that has passed through the objective lens 8 is projected onto the surface of the recording film 1a of the optical disc 1 by being moved in the optical axis direction by the servo signal S2 from the focus servo circuit 16, and the minimum beam A spot is formed on the surface of the recording film 1a of the first disk 1. In this state, the objective lens 8
is in focus.

The objective lens 8 is also movable in a direction perpendicular to the optical axis, and is moved in the direction perpendicular to the optical axis by a servo signal from a tracking servo circuit (not shown). It has become. Then, the focused laser beam that has passed through the objective lens 8 is projected onto the surface of the recording film 1a of the optical disc 1, and is irradiated onto the recording tracks formed on the surface of the recording film 1a of the optical disc 1. It has become. In this state, the objective lens 8 is in a matching track state. In the focused point and focused track state, information can be written and read.

On the other hand, the diverging laser beam reflected from the recording film 1a of the optical disk 1 is converted into a parallel beam by the objective lens 8 when it is focused, and is returned to the polarized beam splitter again. Then, it is reflected by this polarizing beam splitter 7 and guided onto a 4-split photodetector 12 by an astigmatism optical system 11 consisting of a cylindrical lens 9 and a convex lens 10, and an image is formed in a state where defocus appears as a change in shape. It is now possible to do so. The four-split photodetector 12 is composed of four photodetection cells that convert the light imaged by the astigmatism optical system 11 into electrical signals.

Two sets of signals outputted from two photodetection cells arranged diagonally with each other in this four-split photodetector 12 are supplied to an amplifier 17 and an amplifier 8, respectively.

The focus servo circuit 16 includes an error amplifier 19 that inputs the two signals amplified by the amplifiers 17 and 18 and performs error amplification, a phase correction circuit 20 that corrects the phase of the output signal of the error amplifier 19, and a phase correction circuit 20 that corrects the phase of the output signal of the error amplifier 19. An analog switch 21 that controls whether or not to supply the output signal of the circuit 20 to the driver 22, and a driver 2 that amplifies the signal from the analog switch 21 and drives the actuator 21.
2. When this analog switch 21 is turned on by the focus on/off signal S3 from the control circuit 3, a focus servo loop is formed by supplying the signal from the phase correction circuit 20 to the actuator 15 via the driver 22. It has become so.

Further, the output signals from the amplifiers 17 and 18 are supplied to an adder 23. The signal added by the adder 23 reflects the recorded content of the optical disc 1, and is sent to the binarization circuit 24.

The binarization circuit 24 is composed of, for example, a comparator, and performs binarization by comparing the analog signal output from the adder 23 with a predetermined threshold level Th. The reflected light signal S4 binarized by the binarization circuit 24 is supplied to the control circuit 3.

The waveform shaping circuit 32 shapes the waveform of the recording data SIO,
This signal is supplied as a recording pulse signal S7 to a driver 28, which will be described later.

Further, a photodetector 13 constituted by a photoelectric conversion element such as a photodiode, which is provided facing a light emitting port opposite to a light emitting port for recording or reproducing laser light of the semiconductor laser oscillator 5, is configured by a photoelectric conversion element such as a photodiode. When the monitor light from the laser oscillator 5 is irradiated, the monitor light is converted into an electric signal (photocurrent) and supplied to the light output control circuit 14 as the light output monitor signal S5 of the semiconductor laser oscillator 5. ing.

The optical output control circuit 14 controls the optical output of the semiconductor laser oscillator 5 to keep it constant by manually controlling the optical output monitor signal S5 output from the semiconductor laser oscillator 5 to perform feedback control. That is, the optical output control circuit 14 is composed of a laser reproduction light control circuit 51 and a driver 28. Laser reproduction light control circuit 5
The current-voltage conversion circuit 25 that constitutes the semiconductor laser oscillator 5 inputs the optical output monitor signal S5 photoelectrically converted by the photodetector 13 and extracted as a current signal, and converts the light intensity received by the photodetector 13, that is, the semiconductor laser oscillator 5 voltage signal S according to the optical output of
6 and outputs it. A voltage signal S6 outputted from this current-voltage conversion circuit 25 is supplied to an error amplifier 26.

The error amplifier 26 uses the voltage signal S6 as one input and a reference voltage Vs generated by a constant voltage source (not shown) as the other input, compares the two voltages S6 and Vs, amplifies the difference, and calculates the error. It is output as a signal. The reference voltage VS is a constant voltage for obtaining the optical output necessary for reproduction, and the voltage signal S6 is converted to the reference voltage VS.
By feedback control to bring it closer to
A constant optical output can be obtained from the semiconductor laser oscillator 5. The error signal from the error amplifier 26 is supplied to a driver 28.

The driver 28 is supplied with a recording pulse signal S7 corresponding to the information to be recorded from the above-mentioned waveform shaping circuit 32, so that the optical output for recording is output from the semiconductor laser oscillator 5. It is now possible to do so. This driver 28 is constituted by a circuit as shown in FIG.

That is, PNP that generates reproduction light) Rungis Tr
i and PNP that generates recording light) transistor Tr2
Each collector is connected to one terminal of the semiconductor laser oscillator 5, and the other Ω terminal of the semiconductor laser oscillator 5 is grounded. The emitter of the transistor Tri is connected to the power supply V through a resistor R1, and the emitter of the transistor Tr2 is connected to a power supply V through a resistor R2.

At the time of reproduction, the voltage signal output from the laser reproduction light control circuit 51 is input to the base of the transistor Tri, and at the time of recording, the voltage value input at the time of the previous reproduction is held by a sample hold circuit (not shown). A voltage signal is inputted thereto, and these two inputs can be switched depending on whether recording or reproduction is to be performed. In both recording and reproduction, feedback control is performed based on the level of optical output during reproduction. Further, a recording pulse signal S7 is supplied from the waveform shaping circuit 32 to the base of the transistor Tr2, and the transistor Tr2 is turned on and off in accordance with the pulse to generate intermittent laser light of high intensity.

In this way, since one terminal of the semiconductor laser oscillator 5 is grounded, the grounded optical head 4 can be directly attached, so that no misalignment occurs between the semiconductor laser oscillator 5 and the optical head 4. , it is possible to precisely control the irradiation of laser light.

Further, the driver 28 and the waveform shaping circuit 32
It can also be configured as shown in the figure.

That is, the collector of the NPN transistor Tr3, which can operate at high speed, is connected to the collector of the transistor Tr2, and this collector is connected via the diode D to the collector of the transistor Trl. Further, a predetermined voltage is supplied to the base of the transistor Tr2 from the recording power reference voltage generation circuit 32a to keep it in an on state. The base of the transistor Tr3 has recording data S.
10 is supplied with a recording pulse signal S7 shaped by a recording pulse generation circuit 32b, and switching is performed in accordance with this recording pulse signal S7. In the circuit configured as described above, the transistor Tr3 is turned on and off in response to the recording pulse signal S7, and a large current is supplied to the semiconductor laser oscillator 5 through the transistor Tr2 and the diode D during recording, and when not recording, the transistor Tr3 is turned on and off in response to the recording pulse signal S7. is turned on, the current from the transistor Tr2 flows to the ground via the transistor Tr3, and does not contribute to the drive current of the semiconductor laser oscillator 5. By having such a configuration,
Depending on the switching speed of the NPN transistor that can be switched at high speed, the fall/rise characteristics of the current supplied to the semiconductor laser oscillator 5 may become steep.
High-speed operation is possible. In other words, in the above example, P
This eliminates the disadvantage that high-speed operation is not possible due to the use of an NP transistor, and also allows the semiconductor laser oscillator 5 to be directly attached to the grounded optical head 4. Therefore, the semiconductor laser oscillator 5 and the optical There is no deviation between the head 4 and the head 4, and precise laser beam irradiation control is possible.

Next, the operation of the optical disc device configured as described above will be explained.

First, before performing a recording operation, an initial operation is performed to check the validity of the light emission output of the semiconductor laser oscillator 5. That is, a linear motor (not shown) is driven by a control signal from the control circuit 3, and the objective lens 8 is made to face the non-recorded area of the optical disc 1. This non-recording area is provided on the innermost or outermost side of the optical disc 1, and is a portion where no information is recorded. By initially moving the optical head 4 to such a position, even if the laser beam is abnormally emitted for some reason, the recorded data will not be destroyed.Next, the control circuit 3 The analog switch 21 is turned off by outputting a focus on/off signal S3 from the focus on/off signal S3. As a result, the focus servo loop is disconnected, and the objective lens 8 is released from the focusing control. Next, a signal (not shown) for forcibly moving the lens actuator 15 is supplied from the control circuit 3 to the lens actuator 15 via the driver 22 . As a result, the objective lens 8 is forcibly moved to the position shown by the dotted line in FIG. 3, creating a defocused state. In this defocused state, power is supplied to the optical output control circuit 14 to turn on the semiconductor laser oscillator 5 and start outputting a laser beam. As a result, the monitor light generated from the semiconductor laser oscillator 5 is converted into a current according to the light output by the photodetector 13 and output as a light output monitor signal S5. The current-voltage conversion circuit 25 converts this optical output monitor signal S5 into a voltage signal S6 and supplies it to the error amplifier 26. The error amplifier 26 compares the preset reference voltage Vs and the voltage signal S6, and outputs the error as an error signal. This error signal is a signal that reduces the optical output of the semiconductor laser oscillator 5 if voltage signal S6>reference signal VsJ, and increases the optical output of semiconductor laser oscillator 5 if voltage signal S6<reference signal VsJ. be.

By supplying this error signal to the driver 28, a feedback loop is formed and the reference voltage Vs is controlled to be equal to the voltage signal S6, thereby keeping the optical output of the semiconductor laser oscillator 5 constant.

Next, the control circuit 3 drives the actuator 15 via the driver 22 to move the objective lens 8 toward the in-focus position. When it is determined that the in-focus position has been reached, the analog switch 21 is turned on to connect the focus servo loop and complete the initial operation. Thereafter, automatic focus control is performed by a focus servo loop, and normal operations such as reading and writing information from the optical disc 1 are performed.

In such a state, the recording operation is performed as follows. That is, recording data sent from a host device (not shown) is supplied to the control circuit 3, and as a result, pulsed recording data 510 is output from the control circuit 3. This recording data SIO is supplied to the waveform shaping circuit 32 and further supplied to the driver 28. As a result, the semiconductor laser oscillator 5 emits intermittent high-output laser light according to the recording data SIO. This laser beam is converted into a parallel beam by a collimator lens 6 and guided to a polarized beam splitter. The laser beam guided by the polarized beam splitter passes through the polarized beam splitter 7 and enters the objective lens 8, and is focused by the objective lens 8 toward the recording film 1a of the optical disc 1. Information is recorded on top.

On the other hand, the reproduction operation is performed as follows. That is, by supplying the voltage held in a sample hold circuit (not shown) to the driver 28, the semiconductor laser oscillator 5
emits a laser beam with a constant level of low optical power. This laser light is converted into a parallel beam by a collimator lens 6 and guided to a polarizing beam splitter 7. The laser beam guided by the polarized beam splitter passes through the polarized beam splitter 7 and enters the objective lens 8, and is focused by the objective lens 8 toward the recording film 1a of the optical disc 1. Then, the diverging laser beam reflected from the recording film 1a of the optical disc 1 is converted into a parallel beam by the objective lens 8, and returned to the polarized beam splitter again. Then, it is reflected by this polarizing beam splitter 7 and imaged onto a four-split photodetector 12 by an astigmatism optical system 11 consisting of a cylindrical lens 9 and a convex lens 10 . Signals photoelectrically converted by this four-split photodetector 12 are supplied to amplifiers 17 and 18, respectively. and,
One of the signals amplified by the amplifiers 17 and 18 is supplied to the focus servo circuit 16 below the error amplifier 19 and used for focusing control. Further, the other of the signals amplified by the amplifiers 17 and 18 is supplied to the adder 23 to perform addition, and then supplied to the binarization circuit 24.

The binarization circuit 24 outputs a binarized reflected light signal S4 by comparing the signal from the adder 23 with a predetermined threshold level Th. This reflected light signal S4 is then supplied to the control circuit 3. The data is then sent to a host device (not shown) via the control circuit 3, where it is displayed, printed, etc.

As described above, one terminal of the semiconductor laser oscillator 5 is grounded, and the other terminal is driven by the transistor Tri to emit reproduction light to perform reproduction, and the other terminal is connected to the transistor Tr2. Since recording is performed by driving and emitting recording light superimposed on the drive signal of the transistor Tri, there is no need to insulate between the optical head 4 and the semiconductor laser oscillator 5 with an insulating member. , semiconductor laser oscillator 5
There is no deviation due to environmental changes between the optical head 4 and the optical head 4, and precise laser beam irradiation control is possible.

[Effects of the Invention] As detailed above, according to the present invention, there is no need to insulate the semiconductor laser oscillator and the optical head by grounding the package of the semiconductor laser oscillator, and therefore the semiconductor laser oscillator and the optical head It is possible to provide an optical disc device that can precisely control laser light irradiation without causing any deviation between the two.

[Brief explanation of drawings]

1 to 3 show embodiments of the present invention. FIG. 1 is a circuit diagram of the first embodiment showing the configuration of a driving section of a semiconductor laser oscillator, and FIG. 2 is a circuit diagram of the driving section of a semiconductor laser oscillator. FIG. 3 is a block diagram showing the schematic structure of the optical disk device, and FIGS.
The drawings are for explaining a drive section of a conventional semiconductor laser oscillator, with FIG. 4 being a diagram showing the circuit configuration, and FIG. 5 being a diagram for explaining the mounting state of the semiconductor laser oscillator. DESCRIPTION OF SYMBOLS 1... Optical disk, 3... Control circuit, 4... Optical head, 5... Semiconductor laser oscillator (light output means),
12...4-split photodetector, 13...photodetector, 24
... Binarization circuit, 32 ... Waveform shaping circuit, Tri.
...Transistor (first driving means), Tr2...
Transistor (second driving means).

Claims (1)

[Scope of Claims] A light output means for emitting a light beam; a first drive means for grounding one side of the light output means and driving the other side to emit reproduction light; An optical disc device comprising: second driving means for driving the other side to emit recording light.