JPH08297841A - Optical disk device - Google Patents

Abstract

PURPOSE: To generate a track error signal capable of performing a seeking operation at high speed, surely and also stably. CONSTITUTION: The temp. value obtained with a temp. sensor 14 is converted into a voltage value by a temp.-voltage conversion and the obtained voltage value (the analog signal) is converted into a digital signal by an A/D converter 13 and this value is taken into a digital arithmetic part 12, which executes the arithmetic processing of the value to generate a servo gain control signal 104. The analog switch of a gain control amplifier 11 is closed by this gain control signal 104 and the gain of the the amplifier 11 is determined. Then, the amplifier 11 generates a track error signal 102 needed for generating a track cross pulse by being inputted with the track error signal 101 obtained in a differential amplifier 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device, and more particularly to generation of a track error signal required when moving from one track of an information recording medium to another track.

[0002]

2. Description of the Related Art Generally, in this type of optical disk device, an information track formed concentrically or spirally on an information recording medium is irradiated with a semiconductor laser and a laser beam focused by a condenser lens is predetermined. The information is recorded and reproduced by focusing on the light diameter of. When recording / reproducing information in this way, it is necessary to move the optical pickup to a specific information track from a large number of information tracks formed on the information recording medium. At this time, a track error signal (hereinafter referred to as a track error signal) indicating a positional deviation between the information track and the optical pickup is required. Conventionally, the amplitude of the track error signal changes depending on the environmental temperature, and particularly when the temperature is low, the track error signal is remarkably reduced as compared with the normal temperature. For this reason, the track cross pulse necessary for measuring the number of information track crossings cannot often be generated.

[0003] As a conventional publicly known example, actual Kaihei 5-7371
No. 7 publication is known.

This conventional optical recording / reproducing apparatus will be described with reference to the drawings.

FIG. 3 is a block diagram of a conventional optical recording / reproducing apparatus.

This conventional optical recording / reproducing apparatus comprises a track error detecting means, a bandpass filter, a full-wave rectifier, a peak detecting means, an AD converter and a gain control amplifier.

The track error signal detected by the track error detecting means has a bandpass filter to reduce noise components, and a capacitor cuts a direct current component,
Full-wave rectified by full-wave rectifier. The rectified signal is detected by the peak detector, passes through the AD converter, and controls the gain of the gain switching amplifier.

[0008]

In the above-mentioned conventional optical disk device, when the track error signal is generated, the amplitude of the track error signal decreases at low temperature, and the amplitude at this time is for generating the track cross pulse. When the level becomes lower than the slice level, the track error signal cannot be detected, the track cross pulse cannot be generated, and therefore, the count of the number of track crossings is often missed, and stable seek operation is often difficult.

As described above, when the conventional track error signal is generated, the seek operation for moving the optical pickup from a certain track to a target track cannot be performed at high speed and stably.

The optical recording / reproducing apparatus disclosed in Japanese Utility Model Laid-Open No. 5-73717 also has no means for detecting the temperature and cannot prevent the generation of the track cross pulse at a low temperature. Therefore, the same problem as described above is encountered. was there.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical disk device which generates a track error signal capable of performing a seek operation at high speed, appropriately and stably.

Therefore, the optical disk device of the present invention is an optical disk device for recording / reproducing information by moving and positioning an optical pickup with respect to an information track formed in a concentric or spiral shape on an information recording medium. Therefore, there is a track error signal detecting means for detecting the positional deviation between the information track and the optical pickup, a temperature detecting means for detecting the ambient temperature, and an AD for converting the temperature detected by the temperature detecting means from an analog signal to a digital signal. A conversion unit, a gain setting unit that sets a gain value from the digital signal converted by the AD conversion unit, an operational amplifier that amplifies the track error signal amplitude detected by the track error signal detection unit, and a track error signal output from the operational amplifier. Track cross pulse detecting means for detecting the track cross pulse It is characterized in that it comprises.

[0013]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a block diagram showing the basic configuration of the track error signal generation of an embodiment of the optical disk device of the present invention, and FIG. 2 is a waveform diagram showing the track error signal and the track cross pulse of the optical disk device of FIG. .

The track error signal generating portion of the optical disc apparatus of this embodiment is composed of a semiconductor laser 1 arranged in the optical pickup of the optical disc apparatus, a collimator lens 2 which is another component constituting the optical pickup, and a polarized light. Beam splitter 3, quarter wave plate 4, objective lens 6, actuator 5 for driving this objective lens 6 and two-split photodetector, differential amplifier 10 and gain connected to this two-split photodetector 9. Control amplifier 1
1 and a track cross pulse generator 15.

Of these, the semiconductor laser 1 is supplied with an electric current by a laser driving circuit (not shown), and irradiates a laser beam for recording and reproducing information. The collimator lens 2 is for converting the divergent laser beam emitted from the semiconductor laser 1 into a parallel laser beam.
The polarization beam splitter 3 is for separating the light flux reflected from the information recording medium 7, and thereby allows the light flux of the incident light flux to go straight without being bent. 1/4
The wave plate 4 is for changing the polarization state of the laser light flux from linearly polarized light to circularly polarized light, and the condenser lens 8 is for converging the parallel laser light flux to form a minute light spot on the information recording medium 7. belongs to.

Guide grooves for information tracks are formed on the surface of the information recording medium 7 at a fine pitch, and information is recorded along the guide grooves. When the position of the focused light spot on the information recording medium 7 deviates from the center of the information track, the light intensity in the far field of the light reflected by the information recording medium 7 due to the diffraction and scattering of the light by the guide groove is in the track direction. Causes a difference in strength between the left and right. The two-division photodetector 9 catches this intensity difference as a positional deviation of the light spot with respect to the center of the information track, and the track error signal a101
And is provided with at least two photodetection elements that are separately arranged in the left-right direction.

Further, the reflected light reflected by the information recording medium 7 is returned to a parallel light flux by the condenser lens 8 to be 1 /
It is incident on the four-wave plate 4. The polarization beam splitter 3 is
The optical path of the reflected light emitted from the quarter-wave plate 4 is refracted and guided to the two-divided photodetector 9. The two-division photodetector 9 separates and detects the left and right light intensities of the reflected light in the far field. A current indicating the left and right intensities of the reflected light output from the two-divided photodetector 9 is input to the differential amplifier 10.
The differential amplifier 10 outputs a difference output corresponding to the difference in intensity of left and right light, that is, a track error signal a101.

Next, how the track error signal b102 for generating the track cross pulse 103 is generated will be described with reference to FIGS.

201 of FIG. 2 obtained from the differential amplifier 10.
The track error signal a101 indicated by is input to the gain control amplifier 11. The gain control amplifier 11 is composed of one operational amplifier, N feedback resistors, and N analog switches. The N feedback resistors have different resistance values,
The gain of the gain control amplifier 11 is determined by this resistance value. The analog switch is set to close the switch by receiving a signal that becomes a trigger, for example, a signal that changes from low level to high level, and the analog switch and the feedback resistor have a one-to-one correspondence.

On the other hand, the gain value of the gain control amplifier 11 is determined by the ambient temperature, and the temperature sensor 14 detects this ambient temperature. The detected environmental temperature (hereinafter referred to as temperature) is converted by the temperature sensor 14 into a voltage level corresponding to the temperature. The voltage value (analog signal) converted by the temperature sensor 14 is input to the AD converter 13. The AD converter 13 has several comparators, to which different comparator voltages (reference voltages) are input. The voltage input to the AD converter 13 is successively compared by this comparator, converted into a digital value such as "0" or "1" according to the magnitude, and output as a digital signal composed of "0" and "1". The digital signal output from the AD converter 13 is input to the digital arithmetic unit 12. Digital operation unit 1
2 operates the obtained digital value to generate the servo gain control signal 104. The servo gain control signal 104 is connected to each of the N analog switches of the gain control amplifier 11, and the digital arithmetic unit 12 closes only one of the N analog switches to change the gain of the gain control amplifier 11. decide.

The track error signal b102 indicated by 202 in FIG. 2 output from the gain control amplifier 11 is input to the track cross pulse generator 15 with a constant amplitude without being influenced by the environmental temperature, and the track cross pulse generator 15 is supplied. Reference numeral 15 outputs the track cross pulse 103 indicated by 203 in FIG. 2 which is necessary for measuring the number of information track crossings. With this track cross pulse 103, the optical disk device of the present embodiment performs a stable seek operation at high speed and appropriately and constantly.

[0023]

As described above, in the optical disc device of the present invention, when a track error signal is generated, when the optical pickup is moved from one information track to a target information track, the number of information track crossings is measured. The amplitude of the required track error signal is calculated by the temperature sensor, AD converter,
Since it can be kept constant regardless of the ambient temperature by the digital operation unit and gain control amplifier,
It is possible to always generate a stable and accurate track cross pulse, prevent the track cross pulse from not being generated due to a decrease in the track error signal amplitude at low temperatures, and realize a fast, accurate, and stable seek operation. There is an effect.

The optical disk device of the present invention has a means for detecting the temperature, and keeps the amplitude of the track error signal constant regardless of the ambient temperature, so that the optical recording / reproducing device of Japanese Utility Model Laid-Open No. 5-73717 is disclosed. This also solves the problem, prevents the track cross pulse from not being generated at low temperatures, and has the effect of enabling stable seek operation at high speed.

[0025]

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of a track error signal generation of an embodiment of an optical disc device of the present invention.

FIG. 2 is a waveform diagram showing a track error signal and a track cross pulse of the optical disk device of FIG.

FIG. 3 is a configuration diagram of a conventional optical recording / reproducing apparatus.

[Explanation of symbols]

 1 Semiconductor Laser 2 Collimating Lens 3 Polarizing Beam Splitter 4 1/4 Wave Plate 5 Actuator 6 Objective Lens 7 Information Recording Medium 8 Condensing Lens 9 2 Split Photodetector 10 Differential Amplifier 11 Gain Control Amplifier 12 Digital Operation Unit 13 AD Conversion 14 temperature sensor 15 track cross pulse generator 101 track error signal a 102 track error signal b 103 track cross pulse 104 servo gain control signal

Claims (1)

[Claims] 1. An optical disc device for recording and reproducing information by moving and positioning an optical pickup with respect to an information track formed concentrically or spirally on an information recording medium. Track error signal detecting means for detecting positional deviation of the optical pickup; temperature detecting means for detecting ambient temperature; AD converting means for converting the temperature detected by the temperature detecting means from an analog signal to a digital signal; AD converter means Gain setting means for setting a gain value from the converted digital signal, operational amplifier for amplifying the track error signal amplitude detected by the track error signal detecting means, and track cross from the track error signal output from the operational amplifier. Track cross pulse detection means for detecting pulses An optical disk device characterized by.