JPH09288839A - Optical information recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform write processing at a desired high transfer rate in keeping an enough effect to cope with EMI by inexpensive and simple constitution. SOLUTION: An LD 1 is driven via a capacitor 5 as an EMI filter and a transistor 6 by a reading LD driver 7. Then the LD 1 is driven via a capacitor 8 and a switching diode 9 by a writing LD driver 10. A base of the transistor 6 is connected to an output terminal of a reading LD driver, and an emitter is connected via a resistor 11 to a power source Vcc for the circuit and also connected via a capacitor 12 to a high frequency oscillator circuit 2, and then a collector is connected to a cathode of the diode 9 and an anode of the LD 1 respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing apparatus, and more particularly to an optical information recording / reproducing apparatus characterized by a constituent portion of an EMI filter for taking measures against EMI.

[0002]

2. Description of the Related Art Conventionally, in an optical information recording / reproducing apparatus, a high frequency oscillating circuit for reducing noise of a semiconductor laser is also used. As such a high-frequency oscillator circuit, for example, as disclosed in Japanese Patent Publication No. 59-9086, there is one that superimposes a high-frequency current on a direct current applied to a semiconductor laser to reduce noise. Therefore, in the optical information recording / reproducing apparatus, it is necessary to electrically connect the semiconductor laser and the high frequency oscillation circuit.

In a conventional optical information recording / reproducing apparatus as shown in, for example, Japanese Patent Laid-Open No. 6-274920, a semiconductor laser (LD) 101 is provided as shown in FIG.
Is a light source of an optical head (not shown), which is driven in a reproduction mode, a recording mode, and an erasing mode.

The LD 101 is housed in a shield case 104 together with an oscillation circuit for high frequency superposition (hereinafter abbreviated as high frequency oscillation circuit) 102, an unnecessary radiation prevention circuit 103, and the like. The high frequency oscillating circuit 102 is driven only during reproduction and functions to reduce LD noise during reproduction.

At the time of reproduction, the LD 101 has a capacitor C1 and a coil L1 forming an unnecessary radiation prevention circuit 103.
Driven by a read current from a reproducing R LD driver 107 composed of a transistor Q1 and a resistor RE through a high frequency oscillator circuit 1 through a capacitor C2.
A high frequency signal is superimposed by 02. The semiconductor laser 1 is driven by a write pulse from a W LD driver 110 for recording which is switched based on write data via a capacitor C3 and a switching diode Di.

In such an optical information recording / reproducing apparatus which also uses a high frequency oscillating circuit, the high frequency oscillating circuit is surrounded by a conductive package to be grounded and shielded.
When the electrodes are pulled out from the package, the unwanted radiation prevention circuit is configured by using a feedthrough capacitor, a coil, or the like. This unnecessary radiation prevention circuit and shield generally prevent radio interference, that is, take measures against EMI.

[0007]

By the way, recently, demands for high density, high speed, and high transfer rate are remarkably high for optical information recording / reproducing devices. Along with this, in the optical modulation type device that modulates the output of the semiconductor laser to record a signal, it is necessary to increase the modulation speed of the semiconductor laser output and the rising speed thereof.

Considering the influence of L1 and C1 on the write pulse in the conventional optical information recording / reproducing apparatus, an AC equivalent circuit of the load viewed from the W LD driver 110 in FIG. 7 is shown in FIG. Like Note that R
SDi is the forward resistance of diode Di, and RSLD is LD101.
Shows the forward resistance of.

The frequency characteristic of the current ILD flowing through the LD 101 in this equivalent circuit is as shown in FIG. The cutoff frequencies f1 and f2 are

[Equation 1]

[Equation 2] Becomes

As a result, in order to keep the above-mentioned EMI countermeasures and effects, it is necessary to write f1 in equation (1) in an actual optical information recording / reproducing apparatus which requires high density, high speed, and high transfer rate. The value must be set to a value close to the pulse period or pulse width, and this will adversely affect the write profile, so write processing at a high transfer rate cannot be performed, and conversely f1 is not affected. There is a problem in that the EMI effect cannot be obtained when the value is set high.

The present invention has been made in view of the above circumstances, and is an optical system capable of performing a write process at a desired high transfer rate while maintaining a sufficient effect as an EMI countermeasure with an inexpensive and simple structure. It is an object to provide an information recording / reproducing device.

[0012]

The optical information recording / reproducing apparatus of the present invention is an optical information recording / reproducing apparatus for recording and / or reproducing at least information by utilizing a laser beam irradiated on an information recording medium. A semiconductor laser that emits a recording laser beam and a reproducing laser beam; a control unit that controls driving of the semiconductor laser; a recording driving unit that supplies a recording current to the semiconductor laser by a recording driving signal; A high frequency oscillating means connected to the semiconductor laser to reduce laser noise, an unnecessary radiation preventing means for preventing unnecessary radiation accompanying the driving of the high frequency oscillating means, and a reproducing current supplied to the semiconductor laser by a reproducing drive signal. And a drive unit for reproduction.

In the optical information recording / reproducing apparatus of the present invention, the output of the high frequency oscillating means is outputted to the reproducing drive means through the unnecessary radiation preventing means, so that the EMI countermeasure can be achieved by an inexpensive and simple structure. It is possible to perform write processing at a desired high transfer rate while maintaining a sufficient effect.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

1 to 5 relate to the first embodiment of the present invention, FIG. 1 is a block diagram showing the configuration of an optical information recording / reproducing apparatus, and FIG. 2 is a state in which the high frequency oscillation circuit of FIG. 1 is not driven. Showing the emitter voltage of the transistor of FIG. 3, FIG. 3 showing the read current supplied to the LD by the emitter voltage of FIG.
4 is a diagram showing the emitter voltage of the transistor when the high-frequency oscillator circuit of FIG. 1 is driven, and FIG. 5 is a diagram showing the read current supplied to the LD by the emitter voltage of FIG.

In the optical information recording / reproducing apparatus of the present embodiment, a semiconductor laser (LD: laser diode) 1 is a light source of an optical head (not shown) as shown in FIG. And driven in the erase mode. That is, the LD 1 reproduces information,
The optical recording medium (not shown) is irradiated with laser light for recording and erasing.

The LD 1 is housed in a shield case 4 together with an oscillation circuit for high frequency superposition (hereinafter abbreviated as high frequency oscillation circuit) 2 and the like. Here, the high frequency oscillation circuit 2 is driven only during reproduction, and functions to reduce LD noise during reproduction.

The LD 1 has a reproducing semiconductor laser drive circuit (hereinafter, abbreviated as an R LD driver) via a capacitor 5 as an EMI filter and a transistor 6.
It is driven by 7. The drive mode at this time is the reproduction mode. Note that verification can also be performed.

The LD 1 has a recording semiconductor laser drive circuit (hereinafter abbreviated as W LD driver) 1 via a capacitor 8 and a switching diode 9.
It is driven by 0. The drive mode at this time is the recording mode. The erasing may be driven by either the R LD driver 7 or the W LD driver 10. In the present embodiment, hereinafter, it is assumed that the recording side drives the erase mode.

The base of the transistor 6 is connected to the output terminal of the R LD driver 7, and the emitter is connected to the circuit power supply Vcc, for example + 5V, through the resistor 11 and the high frequency oscillation circuit 2 through the capacitor 12. Further, the collector is connected to the cathode of the diode 9 and the anode of LD1. Further, the cathode of the LD1 is connected to the GND through the shield case 4, that is, is grounded.

A change-over switch 16 is connected in parallel between the W LD driver 10 and the GND. The common of the changeover switch 16 is connected to a line connecting the W LD driver 10, and the R side terminal of the changeover switch 16 is connected to GND. Furthermore, the changeover switch 1
6, the W side terminal is open, and the opening and closing is C
It is controlled by the PU 15.

Further, the LD driver 7 for R and the L driver for W
The D driver 10 is controlled by the R control circuit 17 and the W control circuit 18 controlled by the CPU 15. An information signal for recording is given to the W control circuit 18 to be modulated.

In the above configuration, the changeover switch 16 is switched by the control signal from the CPU 15,
The diode 9 turns ON / OFF.

At the time of reproduction, the control circuit 17 for R uses the CPU 1
5 outputs a predetermined indication voltage to the base of the transistor 6, and the transistor 6 converts this indication voltage into a current, and the constant emitter voltage shown in FIG.
As shown in, a constant read current is supplied to the LD 1 (note that the high frequency oscillation circuit 2 is not driven at this time). For example, assuming that the instruction voltage is VR and the voltage between the base and collector of the transistor is VBE, the constant read current IR supplied to LD1 is

(Equation 3) Becomes

Further, the high frequency oscillation circuit 2 is driven only during reproduction under the control of the CPU 15. The high-frequency current from the high-frequency oscillator circuit 2 is output to the emitter of the transistor 6 forming the grounded base circuit via the capacitor 12.
At this time as well, the emitter voltage of the transistor 6 is constant as shown in FIG. 4, and as a result, the high frequency current from the high frequency oscillation circuit 2 is superimposed on the constant read current from the circuit power source (see FIG. 3), and the LD1 is fed to the LD1. Causes a read current as shown in FIG. For example, assuming that the high frequency current from the high frequency oscillation circuit 2 is IHFM, the read current IRHF supplied to the LD1.
M is

## EQU4 ## IRHFM = IR-IHFM (4)

At this time, at the time of reproduction, the changeover switch 16 is connected to the R side by the control signal from the CPU 15. The forward voltage of LD1 is about 2V, for example.
Therefore, a reverse voltage, for example, -2 V is applied to the diode 9 to turn it off. That is, since the W LD driver 10 is separated from the LD 1 and the high frequency oscillation circuit 2, unnecessary radiation from the W LD driver 10 system can be prevented.

On the other hand, at the time of recording / erasing, the LD driver 10 for W controls the LD 1 to record / erase information.

In this embodiment, the read current IRHFM corresponds to the collector current of the transistor 6, and the base current of the transistor 6 at this time is IRH.
Since it is FM / hfe, the high frequency current that tries to go out from the shield case 4 is 1/1 of the current supplied to the LD1.
It becomes hfe. Therefore, the EMI filter placed on the base side of the transistor has a sufficient effect only with the one-stage capacitor 5 described above, and the EMI filter can be inexpensively and easily configured. Further, the capacitor 5 constituting the EMI filter does not become a load of the LD1 write drive system by the W LD driver 10, and the LD1 write drive is performed with a desired write profile, so that write processing at a high transfer rate is possible. Becomes

Since it does not become a load of the light drive system of the LD 1, it is possible to increase the capacity of the capacitor 5, and by using a high capacity capacitor, E
The effect as the MI filter can be improved.

FIG. 6 is a structural diagram showing the structure of an optical information recording / reproducing apparatus according to the second embodiment of the present invention.

Since the second embodiment is almost the same as the first embodiment, only different points will be described, the same components will be denoted by the same reference numerals, and description thereof will be omitted.

In this embodiment, an FET 31 is used as shown in FIG. 6 in place of the transistor of the first embodiment. At this time, the constant read current IR supplied to LD1 is

(Equation 5) Becomes IDSS is a drain current when the gate and the source are short-circuited, and gm is a mutual conductance.

Other configurations and operations are the same as those of the first embodiment.

In the present embodiment as described above, the read current IRHFM corresponds to the drain current of the FET 31, and the gate current of the FET 31 at this time is zero due to the nature of the device. Therefore, the EMI filter inserted on the gate side of the FET 31 has the same structure as that of the first embodiment.
A sufficient effect can be obtained only by the above-mentioned capacitors 5 in stages, and the EMI filter can be constructed inexpensively and easily. In addition, the capacitor 5 that constitutes the EMI filter
Is not a load on the write drive system of the LD1 by the W LD driver 10, and the LD1 has a desired write profile.
By performing the write drive of, it becomes possible to perform write processing at a high transfer rate.

[0035]

As described above, according to the optical information recording / reproducing apparatus of the present invention, the output of the high frequency oscillating means is outputted to the reproducing driving means through the unnecessary radiation preventing means, which is inexpensive and simple. With the configuration, there is an effect that the write processing can be performed at a desired high transfer rate while maintaining a sufficient effect as an EMI countermeasure.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a configuration of an optical information recording / reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing the emitter voltage of a transistor when the high-frequency oscillator circuit of FIG. 1 is not driven.

FIG. 3 is a diagram showing a read current supplied to an LD according to the emitter voltage of FIG.

FIG. 4 is a diagram showing an emitter voltage of a transistor when the high frequency oscillation circuit of FIG. 1 is driven.

5 is a diagram showing a read current supplied to an LD according to the emitter voltage of FIG. 4;

FIG. 6 is a configuration diagram showing a configuration of an optical information recording / reproducing apparatus according to a second embodiment of the present invention.

FIG. 7 is a configuration diagram showing a configuration of a conventional optical information recording / reproducing apparatus.

8 is a circuit diagram showing an AC equivalent circuit of a load of the optical information recording / reproducing apparatus as seen from the LD driver for W in FIG.

9 is a characteristic diagram showing frequency characteristics of a write current flowing through an LD in the AC equivalent circuit of FIG.

[Explanation of symbols]

 1 ... LD 2 ... High-frequency oscillator circuit 4 ... Shield case 5, 8, 12 ... Capacitor 6 ... Transistor 7 ... R LD driver 9 ... Diode 10 ... W LD driver 11 ... Resistor 15 ... CPU 16 ... Changeover switch 17 ... R Control circuit 18 ... W control circuit

Claims (3)

[Claims] 1. A semiconductor laser for emitting a recording laser beam and a reproducing laser beam in an optical information recording / reproducing apparatus for recording and / or reproducing information at least by utilizing a laser beam irradiated on an information recording medium. A control means for controlling the drive of the semiconductor laser; a recording drive means for supplying a recording current to the semiconductor laser according to a recording drive signal; and a high-frequency oscillation means connected to the semiconductor laser for reducing laser noise. An unnecessary radiation preventing means for preventing unnecessary radiation accompanying the driving of the high frequency oscillating means, and a reproducing drive means for supplying a reproducing current to the semiconductor laser by a reproducing drive signal. Is output to the reproduction drive means through the unnecessary radiation prevention means. 2. A semiconductor laser for emitting a recording laser beam and a reproducing laser beam in an optical information recording / reproducing apparatus for recording / reproducing at least information by utilizing a laser beam irradiated on an information recording medium. A control means for controlling the drive of the semiconductor laser; a recording drive means for supplying a recording current to the semiconductor laser according to a recording drive signal; and a high-frequency oscillation means connected to the semiconductor laser for reducing laser noise. An unnecessary radiation preventing means for preventing unnecessary radiation accompanying the driving of the high frequency oscillating means; a shield means for housing the semiconductor laser and the high frequency oscillating means; A reproducing drive means for supplying a reproducing current to the semiconductor laser according to a signal, and outputting the output of the high frequency oscillating means to the unnecessary radiation. Optical information recording and reproducing apparatus and outputs to the reproduction drive means via the stop means. 3. The reproducing drive means is a transistor or an FET for supplying a reproducing current to the semiconductor laser according to a reproducing drive signal, and an output terminal is a collector or a drain, and an output of the high frequency oscillating means. The optical information recording / reproducing apparatus according to claim 1, wherein the information is output to an emitter or a source of the reproducing drive means.