JPS63124235A - Optical type recording and reproducing device - Google Patents

Abstract

PURPOSE:To stabilize a recording bit and to suppress the generation of the secondary harmonic distortion of a reproduced signal due to a temperature variation on a disk at a low level by controlling the light emitting energy of a semiconductor laser to be a light source of an optical head based on a signal for detecting temperature of the surface of the disk or atmospheric temperature. CONSTITUTION:A temperature sensor 5 detects the surface temperature of the disk 1 or its atmospheric temperature and temperature information converted into an electric signal is sent to a laser control part 7. The light emitting energy of the semiconductor layer for the optical head 3 is controlled so that recording conditions appropriate for the temperature of the disk 1 are satisfied at the time of recording the information. Namely, the modulating waveforms of semiconductor laser beams are controlled so that the maximum value Pmax of the modulation waveforms is increased at a low temperature or reduced at a high temperature. Consequently the variation of the optimum value of recording laser energy due to the variation of the atmospheric temperature of the disk 1 can be processed and recording bits formed on the disk 1 are uniformed without being influenced by the variation of the atmospheric temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical recording and reproducing device, such as an optical disk device, that optically records and reproduces information.

Conventional TechnologyThe modern era is called the information age9, and the technology development of high-density, large-capacity memory, which forms the core of this era, is actively being carried out.

In addition to the above-mentioned high density and large capacity, the capabilities required of memory include high reliability and high speed access, and optical disk memory is attracting the most attention as a device that satisfies all of these requirements. An optical disk memory is a device that optically records information on a recording medium, and recently, a lot of research has been conducted on magneto-optical disks that can also erase recorded information.

Optical disk memory generally records information using heat. That is, recording bits are formed by condensing light from a light source onto a disk as a minute light spot through a lens system and converting light energy into thermal energy. By applying intensity modulation to the light source, a series of recording pits are formed on the disk and are recorded as information.

Conventionally, regarding information recording technology for optical recording and reproducing devices,
Many reports have been made.

Hereinafter, the conventional optical information recording/reproducing apparatus as described above will be explained with reference to the drawings.

FIG. 6 is a schematic configuration diagram of a conventional optical recording/reproducing device. In Fig. 6, 1 is a disk, 2 is a motor,
3 is an optical head, and 4 is a laser drive circuit. The operation of the conventional example configured as described above will be explained below. An optical head 3 composed of optical components such as a semiconductor laser and an objective lens focuses a laser beam onto a disk 1 rotated by a motor 2 to record and reproduce information. There are two types of rotation control methods for the motor 2 that rotates the disk 1: a constant angular velocity control method (CAW) and a constant linear velocity control method (CLV).

In an OLV, the relative speed (linear velocity) between the optical spot formed on the disk 1 by the optical head 3 and the recording track on the disk 1 does not change from the inner circumference to the outer circumference of the disk 1, so information recording is not possible. The driving state of the semiconductor laser of the optical head 3 may always be constant.

In CKV, since the linear velocity of the disk 1 is different between the inner and outer circumferences, it is difficult to form uniform recording bits on the inner and outer circumferences of the disk 1 under the same semiconductor laser driving conditions as in CLV. Therefore, disk 1 of Optical Herad 3
Depending on the top position, the recording energy is less on the inner circumference,
A method has been used in which the driving state of the semiconductor laser of the optical head 3 is changed by the laser driving circuit 4 so that the number of semiconductor lasers increases at the outer periphery.

Problems to be Solved by the Invention However, such a conventional method is good when the environment in which the disk 1 is mounted, especially when the temperature is constant, but a big problem arises when there are large fluctuations. This is due to the fact that the recording principle of the disk is thermal recording, as described above. If the semiconductor laser drive state during information recording is optimized at room temperature (20 to 30 degrees Celsius), generally speaking, if the temperature of the disk 1 rises, the
There is a tendency for recording bits formed on the top to become larger, and recording bits formed on the bottom to become smaller. Therefore, when a disc recorded in such a state is reproduced, the duty ratio of the reproduced waveform fluctuates compared to when the disc is recorded at room temperature.

That is, as shown in FIG. 7, as the temperature deviates from room temperature, the second harmonic distortion of the reproduced waveform increases, leading to a significant deterioration in signal quality.

The present invention has been made in view of the above-mentioned conventional problems, and provides an optical recording/reproducing device that can suppress the occurrence of second-order harmonic distortion during information recording due to changes in the environmental temperature of the entire device or the disk. The purpose is to provide

Means for Solving the Problems In order to achieve the above object, the optical recording/reproducing apparatus of the present invention includes a temperature detecting means located near a disk and detecting the surface temperature of the disk or the ambient temperature; The laser control circuit is configured to control the light emission energy of a semiconductor laser, which is a light source of the optical head, based on the signal detected by the means.

According to the above-described structure, the present invention reduces or increases the emission energy of the semiconductor laser during information recording in accordance with the rise or fall of the surface temperature of the disk or the ambient temperature, thereby changing the formation state of recording bits on the disk. This makes it possible to stabilize the reproduction signal and suppress the occurrence of second-order harmonic distortion in the reproduced signal.

Embodiment One embodiment of the present invention will be described based on the accompanying drawings.

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

In FIG. 1, 1 is a disk, 2 is a motor, 3 is an optical head, 6 is a temperature sensor, 6 is a temperature detection circuit, and 7 is a laser control circuit.

The operation of an embodiment of the optical recording/reproducing apparatus configured as described above will be explained below. An optical head 3 composed of optical components such as a semiconductor laser and an objective lens focuses a laser beam onto a disk 1 rotated by a motor 2 to record and reproduce information. Temperature set/su5
is provided near the disk 1 to detect the surface temperature of the disk 10 or the ambient temperature. The temperature information converted into an electrical signal by the temperature detection circuit 6 is sent to the laser control circuit 7. During information recording, the laser control circuit 7 refers to the temperature information and controls the emission energy of the semiconductor laser of the optical head 3 so as to satisfy recording conditions suitable for the temperature of the disk 1.

FIG. 2 is a characteristic diagram in which the horizontal axis shows the disk ambient temperature and the vertical axis shows the recording laser energy on the disk necessary to form uniform recording bits. This shows that, compared to room temperature (20 to 30'C), a large recording laser energy is required at low temperatures, and conversely, it is necessary to reduce the recording laser energy at high temperatures. Note that since the characteristic curve shown in FIG. 2 differs depending on the type of recording film of the disk, only an example thereof is shown here. Therefore, the laser control circuit 7 satisfies the characteristics shown in FIG.
The light emission energy of the semiconductor laser of the optical head 3 is controlled.

FIG. 3 shows the modulation waveform of the semiconductor laser emission output of the optical head 3 during information recording.

In FIG. 3, the horizontal axis is time and the vertical axis is laser output.

The maximum value of the modulation waveform is Pma) C + the minimum value is Pm l n
*Pulse period is ``e Pma) (pulse width is W
shall be.

The four types of output characteristics of the means for controlling the emission energy of the semiconductor laser of the optical head 30 by the laser control circuit 7 are as follows.
As shown in the figure.

For the fourth hole, the horizontal axis is the disk atmosphere temperature, and the vertical axis is pmhx.
FIG. In order to satisfy the recording conditions shown in FIG. 2, the semiconductor laser modulation waveform is controlled so that PmaX is large at low temperatures and small at high temperatures.

Figure 4 is a graph in which Pm1n is plotted on the vertical axis.

At low temperatures, Pm
The semiconductor laser modulation waveform is controlled so that 1n is large and becomes small at high temperatures.

FIG. 4C is a graph in which the duty ratio w/T is plotted on the vertical axis. In order to satisfy the recording conditions shown in FIG. 2, the semiconductor laser modulation waveform is controlled so that w/T is large at low temperatures and small at high temperatures.

By implementing all of the output characteristics of the three types of control means described in FIG. 4, it is possible to control the emission energy of the semiconductor laser.
It is possible to cope with the variation in the optimum value of the recording laser energy due to the variation in the disk ambient temperature, as shown in FIG. Therefore, the recorded bits formed on the disk are not affected by fluctuations in the ambient temperature of the disk and are uniform, so the quality of the reproduced signal is stabilized.

FIG. 5 shows the state of occurrence of second-order harmonic distortion in this embodiment. Compared to the case where the present embodiment shown by the broken line in FIG. 6 is not adopted, the present embodiment shown by the solid line can suppress the occurrence of second-order harmonic distortion due to fluctuations in the disk ambient temperature.

As described above, according to this embodiment, the temperature sensor 6 provided near the disk 1 detects the surface temperature of the disk 1 or the ambient temperature, and the temperature detection circuit 6 converts the temperature into an electrical signal. By controlling the emission energy of the semiconductor laser of the optical head 30 by the laser control circuit 7 with reference to the temperature information obtained by the disc, it is possible to suppress the occurrence of second-order harmonic distortion of the reproduced signal due to fluctuations in the disk ambient temperature. This allows you to obtain high-quality playback signals.

In this embodiment, three types of semiconductor laser emission energy control means of the optical head 3 by the laser control circuit 7 are described in FIG. 4, but the emission energy of the semiconductor laser can be controlled by combining these three types. It's okay.

Effects of the Invention The present invention is an optical recording/reproducing device that includes a temperature detection means that is located near the disk and detects the surface temperature of the disk or the ambient temperature, and a temperature detection means that detects the temperature of the optical head based on the signal detected by the temperature detection means. A laser control circuit that controls the emission energy of a semiconductor laser as a light source, and decreases or increases the emission energy of the semiconductor laser during information recording in accordance with the rise or fall of the disk surface or ambient temperature. In addition, it is possible to stabilize the formation state of recording bits on the disk, suppress the occurrence of second harmonic distortion of the reproduced signal due to temperature fluctuations of the disk, and obtain a high-quality reproduced signal. can.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a schematic configuration of an optical recording/reproducing apparatus according to an embodiment of the present invention, and FIG. Figures 3, 4, and 6 are characteristic diagrams for explaining its operation, Figure 6 is a block diagram showing the configuration of a conventional optical recording/reproducing device, and Figure 7 is a diagram for explaining its operation. It is a characteristic diagram. 1...disc, 2...motor, 3.
...Optical head, 5...Temperature sensor, 6
...Temperature detection circuit, 7...Laser control circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure Oto 20 30 4t) , 50 6theta disc temperature, friend (Tji 3rd figure D time □ Figure 4 Te deaf school♂! Cooling temperature range (Shining disk 4 to concave air ('C) Figure 5 Tensuf air temperature ΔTosen c'C) Figure 6 !Tiff S ambient air temperature (6c)

Claims (4)

[Claims] (1) A disk that is an information recording medium, an optical head that is composed of optical components such as a semiconductor laser and an objective lens and records and reproduces information on the disk, and an optical head that is located near the disk and that is connected to the disk. The laser control circuit includes a temperature detection means for detecting the temperature of a surface or an atmosphere, and a laser control circuit for controlling the light emission output of a semiconductor laser that is a light source of the optical head, and the laser control circuit is configured to detect a signal detected by the temperature detection means. An optical recording/reproducing apparatus based on the above, comprising a control means for decreasing or increasing the emission energy of the semiconductor laser during information recording in accordance with the rise or fall of the surface temperature of the disk or the ambient temperature. (2) The optical recording and reproducing apparatus according to claim 1, wherein the control means in the laser control circuit increases or decreases the maximum value of the intensity-modulated semiconductor laser light output. (3) The optical recording and reproducing apparatus according to claim 1, wherein the control means in the laser control circuit increases or decreases the minimum value of the intensity-modulated semiconductor laser light output. (4) The optical recording and reproducing apparatus according to claim 1, wherein the control means in the laser control circuit increases or decreases the pulse width duty ratio of the intensity-modulated semiconductor laser light output.