JPS58177534A - Optical recording device - Google Patents

Abstract

PURPOSE:To obtain a device which records and reproduces a signal of good quality even when an in-use ambient temperature range is wide by varying the intensity of a light beam according to the ambient temperature of a recording medium. CONSTITUTION:The output of a temperature sensor 18 is processed by a sensor output processing circuit 19, whose output is led to a semiconductor laser driving circuit 3 to perform such control that the light emission power of a semiconductor laser 4 is increased at low temperature and decreased at high temperature. To obtain a reproduction output in an invariably constant state, a disk is supplied with high irradiation power at low temperature and with low irradiation power at high temperature. For this purpose, the center value of a current is increased when the in-use ambient temperature is low and decreased when high by the output of the sensor output processing circuit 19 to realize the desired control. In this case, a bias controlling method is employed to increase and decrease the current center value.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention irradiates a recording medium with a light beam such as a laser,
The present invention relates to an optical recording device that records information such as video signals by the heating effect caused by the irradiation of the light beam.

Conventionally, as seen in the example of an optical video recording system, a signal is recorded on a disk-shaped recording medium (hereinafter referred to as a disk) as a concentric circle or a spiral recording trajectory in a concave-convex or shading-like manner. As such, devices that perform high-density recording and reproduction are being considered. In such a device,
The recorded signal is FM modulated or PGM processed,
It is converted into two Buddhist monk titles, recorded as recording pits on the disc body, and then reproduced.

In addition, in the case of such a recording/reproducing device, the recording pits are generally minute, around 1 μmφ, and the recording track pinch is also performed at about 2 to 3 μm, so it is possible to obtain a large-capacity signal recording/reproducing device. .

In such a device, when recording a signal as a convexoconvex or a dark and light focus using a laser beam, the light beam is generally focused to a diameter of 1 μm or less,
The heat is used to create unevenness on the recording medium and to create shading in focus. When creating a device using the above recording method to record and reproduce signals, the environment in which the device is used is generally not kept at a constant temperature, for example, in an environment with a temperature difference of about 0°C to 40°C. You have to think about how it will be used.

If you try to record signals in a wide range of operating environment temperature conditions using a recording method that uses the heat of a light beam such as a laser, as described above, if the environment is low temperature, the recording will be insufficient. , in the case of high temperatures, there is a possibility that the light intensity of the light beam is too strong.

SUMMARY OF THE INVENTION An object of the present invention is to solve these drawbacks and provide an apparatus that can always record and reproduce signals of good quality even in a wide range of environmental temperatures.

First, according to FIG. 1, we will explain about a slave optical recording and reproducing device that records and reproduces one frame of 11 still images on one track of one rotation of the disk.4.The video signal input from the signal input terminal 1 is as follows. The signal is processed by the signal processing circuit 2 and guided to the semiconductor laser drive circuit 3.

The light corresponding to the video signal emitted from the semiconductor laser 4 passes through a lens system 6, is reflected by a polarizing beam splitter 6, passes through a false plate 7, and is focused through an aperture lens 8, and is directed onto a disk 1o. The illuminating lens 8 moves to follow the shaking of the Dinuk 10, and operates so that the light beam is always focused on the disk 10.

On the other hand, during playback, the semiconductor laser 4 is operated to output light at a constant level that is weaker than during recording, and the disk 10 is
The more reflected light beam passes through the plate T, passes through the polarizing beam splitter 6, and enters the light receiver 14.

The electrical signal output from the light receiver 14 is amplified by a head amplifier 15, passes through a signal processing circuit 16 including demodulation, and is output from a signal output terminal 17 as a reproduced signal.

With such a device, one NTSC image can be captured with one rotation of the disk.
When recording frames, the motor 11 is set at 180 OrpH.
Rotate with . The one-rotation detector 12 detects one rotation of the motor 11, processes the signal in the one-rotation detection processing circuit 13, and supplies a one-rotation signal to the semiconductor drive circuit 3 when recording an image signal. A signal of only one frame is supplied to the semiconductor laser 45 = . In this way, one frame of image can be recorded in one rotation of the disk, and one image can be recorded one after another in one rotation of the disk.

When recording signals on the disk using the apparatus described above, the heat of a light beam, such as a laser beam, narrowed down to 1 μm or less may be used to record the signal onto the disk.

FIG. 2 shows an example of a pair of reproduction outputs of irradiation power onto a disc. In the case of a disc material exhibiting the characteristics shown in Figure 2, when the irradiation power is in the ■ area, the signal recording and reproducing quality is poor, when the irradiating power is in the ■ area, good quality signal recording and reproducing characteristics are obtained, and when the irradiation power is in the 0 area, the signal recording and reproducing quality is poor. In the case of power, the condition differs slightly depending on the recording material used, but for example, the material evaporates, resulting in poor signal recording and reproduction quality.

When trying to record and reproduce high-quality signals using such materials, the irradiation power must be selected in the region of ■. However, since the heat of the light beam is used during recording, the operating environment temperature , for example, at 0° C. 6·′-The region (■) may become substantially narrower between this case and the case at 40° C.

Due to variations in the irradiation power settings, variations in the disc material, etc., and when the operating environment temperature is low,
Conventionally, the inconvenience of entering the O range at high temperatures has been common.

The present invention proposes a method to eliminate such drawbacks.

FIG. 3 shows an embodiment of the present invention. In FIG. 3, the same numbers as in FIG. 1 indicate the same things.

In FIG. 3, the output of the temperature sensor 18 is processed by a sensor output processing circuit 19, and this processed output is guided to the semiconductor laser drive circuit 3, and the emission power of the semiconductor laser 4 is increased to a high output when the temperature is low, and a high output when the temperature is low. When this happens, the output is controlled to be low.

Next, we will explain the above controls in a little more detail.

FIG. 4 shows the difference in the relationship between the irradiation power and the reproduction output shown in FIG. 2 depending on the operating environment temperature. As can be seen from FIG. 4, -::, in order to always obtain reproduction output in the state (2), a high irradiation power is supplied to the disk when the temperature is low, and a low irradiation power is supplied to the disk when the temperature is high.

FIG. 6 shows a relationship between the supply current and the emission power of the semiconductor laser.

Normally, if a current is passed through the semiconductor laser around the current value of ■ in Figure 6, the emission power will be centered around the value of ■ [F]
Those that change from ◎ to ◎ are output.

■By controlling the current center value from outside,
If it is made thicker, the luminous power will increase, and if it is made smaller, the luminous power can be reduced.

Therefore, in the output of the sensor output processing circuit 19 shown in Fig. 3, when the operating environment temperature is low, increase the current center value (■), and when the operating environment temperature is high, decrease the current center value (■) to obtain the desired result. You will be able to control the (2) To control the current center value up and down (Vf), a general bias control method can be used, and detailed explanation will be omitted here.

JP-A-58-177534 (3)' As explained above, by using the present invention, signals can be recorded in a wide range of operating environment temperature conditions using a recording method that utilizes the heat of a light beam such as a laser. When attempting to reproduce the data, it is possible to achieve a great effect in that high-quality recording and reproduction can always be realized.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a conventional optical recording and reproducing device that records and reproduces one frame of still images on one track of one rotation of a disc, Figure 2 is a relationship between the irradiation power on the disc and the pair of reproduction outputs, and Figure 3 The figure is a block diagram of an optical recording/reproducing device according to an embodiment of the present invention, FIG. 4 is a diagram explaining how the relationship diagram in FIG. 2 changes due to changes in the operating environment temperature, and FIG. FIG. 3 is a diagram showing current versus light emission power. 3... Semiconductor laser drive circuit, 4...
Semiconductor laser, 1o...Disc, 18...
...Environmental temperature detector, 19...Sensor output processing circuit.

Claims (1)

[Claims] A light beam whose intensity is modulated according to the information signal to be recorded is irradiated onto a recording medium having a recording layer on which recording is performed by heat generated by the irradiation of the light beam, and the intensity of the light beam is adjusted depending on the temperature near the recording medium. An optical recording device characterized by changing intensity.