JPH0490141A - Optical recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve characteristics of recording on optical card by performing a temp. compensation with emitting light intensity relative to a temp. characteristic of the optical card only when a difference between a temp. of the optical card itself and a temp. inside the device is discriminated. CONSTITUTION:A temp. inside the device is detected by a temp. sensor 3, and a compensation value is decided by a controller 9 from the temp. inside the device, and then the compensation value is generated from a compensation value setting circuit 10. The time required for reaching a heat balance between the temp. inside the device and the temp. of the optical card 1 is set to a counter circuit 7. When the optical card 1 is inserted into the device, the insertion of the optical card 1 is detected by an insertion detecting sensor 8, and measuring of the time is commenced by the counter circuit 7. Then, when a counting value becomes zero, a compensation deciding signal is outputted from a changeover signal generating circuit 11 to go through a compensation function deciding means 4, and is compensationally added by an operator amplifier 5, so that an output from a laser driving circuit 6 is corrected and impressed upon a semiconductor laser 12. By this method, information is properly recorded and reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical recording/reproducing device for optically recording/reproducing information using a recording medium such as an optical card.

[Conventional technology]

Optical recording and reproducing devices irradiate a recording medium with a light beam emitted from a semiconductor laser, which is a light source, but it is well known that the efficiency of output power with respect to drive current of semiconductor lasers changes depending on the surrounding temperature, aging, etc. It is. There are various methods for recording information using a light beam, such as phase difference detection, phase change, and magneto-optical methods, but all of them are performed by applying heat to the recording medium by irradiating the recording medium with a light beam. That's what they have in common.

Therefore, it is necessary that the temperature of the irradiated light is optimal for recording, and if the intensity of the irradiated light deviates from this optimal point, the recording characteristics such as the size of the recording pit will change, and the reproduced signal output will deteriorate. This may cause problems such as an increase in the error rate, resulting in a decrease in the reliability of recorded information.

For this reason, various countermeasures have been taken in the past. For example, in Japanese Patent Application Laid-Open No. 59-140647, the ambient temperature of the recording medium is measured by a temperature detection means such as a thermistor, and the output of the semiconductor laser is adjusted based on this. A method is disclosed. FIG. 4 shows a semiconductor laser drive circuit for temperature compensation, which includes a temperature detection circuit including a thermistor 21, a constant current source including an operational amplifier 22, and a current switching circuit including a semiconductor laser 23, etc. Each block is provided.

[Problem to be solved by the invention]

However, although the conventional recording/reproducing apparatus can adjust the output of the semiconductor laser according to the ambient temperature of the recording medium and maintain the optimum intensity of the irradiated light, it cannot compensate for the temperature characteristics of the recording medium itself. Therefore, even if it is possible to stabilize the recording characteristics by optimizing the intensity of the irradiated light from the semiconductor laser, it is impossible to prevent changes in the recording characteristics due to the temperature characteristics of the recording medium. In particular, when the recording/reproducing device and the recording medium are placed in different locations, there is a large difference between the temperature inside the device and the temperature immediately after the recording medium is inserted into the device. It is not possible to stabilize the recording characteristics only by adjusting the output. In such a case, adjusting the output of the semiconductor laser based on the ambient temperature of the recording medium may even have the opposite effect.

On the other hand, providing a non-contact temperature detection means to measure the temperature of the recording medium itself, or adopting a configuration in which a contact type detection means is brought into contact with the recording medium, has the disadvantage of increasing the cost of the device. .

The present invention is proposed to solve the above-mentioned problems, and provides an information recording and reproducing device that can perform appropriate recording and reproducing of information by compensating for the temperature characteristics of a recording medium when necessary in controlling the intensity of irradiated light. It is intended to.

[Means and operations for solving the problems] In order to achieve the above object, the present invention provides an optical recording and reproducing device that records and reproduces information by irradiating a recording medium with a light beam. The present invention is an optical recording/reproducing apparatus comprising: a means for controlling the light quantity of the light beam based on the detection output; and a means for determining whether or not the detection output is to be used for controlling the light quantity of the light beam.

By providing the compensation function selection means in this manner, compensation for the temperature characteristics of the recording medium in controlling the light amount of the light beam can be performed only when the temperature of the recording medium almost matches the temperature detected by the temperature detection means in the apparatus. can.

〔Example〕

FIG. 1 shows a first embodiment of the present invention and is a block diagram for explaining the present invention in detail. In this embodiment, the time elapsed after the optical recording medium was inserted into the device is measured, and depending on the heat capacity of the optical recording medium, it is determined whether or not the device internal temperature detection output is used to control the light amount of the optical beam. It was designed to do so. Optical recording media include optical disks, magneto-optical disks, etc., but here we will explain using an optical card as an example. When the optical card 1 is inserted into the apparatus, it is transported into the apparatus by a transport means. In this case, the insertion detection sensor 8 detects the insertion of the optical card I, and the counter circuit 7 starts measuring the time after insertion.

A semiconductor laser 1 is connected to the optical card 1 by a laser drive circuit 6.
A light beam is emitted from 2, and information is recorded and reproduced. In this case, in order to optimally maintain the irradiation light intensity depending on the temperature inside the device, the temperature sensor 3 detects the temperature inside the device, and the controller 9 determines a compensation value based on the temperature inside the device. A compensation value is then generated from the compensation value setting circuit 10.

Further, since the inserted optical card 1 is at a temperature different from the temperature inside the device, it is not appropriate to irradiate the optical card 1 with a light beam as it is. Therefore, it is necessary to take a timing at which the internal temperature of the device and the optical card reach thermal equilibrium. Even if the optical card 1 is inserted into a device at a certain temperature, the internal temperature of the device is hardly affected by the optical card 1 because the thermal capacity of the device is larger than that of the optical card 1.

However, if the temperature of the optical card 1 is 30°C, the heat capacity is 10Ca2/g, the weight of C1 is 1g, and the temperature inside the device is 20°C, it takes 100°C for both to reach thermal equilibrium.
Cal needs to be supplied from the recording medium. Therefore, considering thermal conductivity, approximately 1
If it takes seconds, it will take about 10 seconds to reach thermal equilibrium.

Here, since it is not possible to measure the temperature of the optical card 1, the time required to reach thermal equilibrium is set. The larger the difference between the temperature inside the device and the temperature of the optical card 1, the longer it takes to reach thermal equilibrium, but the above time should be set based on the operating temperature range of the device and the optical card 1. Become. Here, the operating temperature range of the device and optical card 1 is 5.
'C~40''C8 When the current temperature inside the device is T, the maximum value of the temperature difference is the larger value M of 40-T and T-5.

The time t required to reach thermal equilibrium at that time is determined as follows.

t = MxlO/10 (seconds) In this way, the time t is determined based on the temperature T inside the device, and it is set in the counter circuit 7.

When the count clock of the counter circuit 7 is 1 ms, the cent value is 1000Xt. The count value is decremented to measure time, and when the count value reaches 0, a compensation determination signal is output from the switching signal generating circuit 11 that generates a compensation function determination signal, and the compensation value is incorporated.

Note that the switching signal generation circuit is configured to latch the pollo output of the counter circuit 7 into a flip-flop. Further, the compensation function determining means 4, which is a means for determining the temperature compensation function, may be configured using an analog switch.

In this way, the output from the laser drive circuit 6 is corrected and applied to the semiconductor laser 12 by passing through the compensation function determining means 4 and adding a compensation value by the operational amplifier 5 for compensating the output value of the irradiated light. This is what happens. On the other hand, if an instruction is received to record data until the count value reaches 0, the compensation function determining means 4 will not select a compensation value. Therefore, the output of the laser drive circuit 6 is directly outputted from the operational amplifier 5. In this way, the temperature inside the device and the optical card 1
Appropriate recording is possible by recording earlier than the time required to reach thermal equilibrium with the temperature, and if temperature compensation is not possible, recording again after a certain period of time.

FIG. 2 shows a second embodiment of the present invention, and parts corresponding to those in the first embodiment are given the same reference numerals. In this embodiment, the temperature change gradient inside the device is measured, and based on the magnitude of the gradient, it is determined whether or not the device internal temperature detection output is used for controlling the light amount of the light beam. For this purpose, in this embodiment, a differentiation circuit 13 for differentiating the output of the temperature sensor 3 is used.
has been established. Then, the optical card 1 inserted into the device
Based on the temperature sensor 3 provided near the optical card 1
Temperature compensation is performed by capturing the temperature change through the differential circuit 13. The other configurations are the same as those in the first embodiment.

FIG. 3 is an explanatory diagram showing a state in which the temperature change is differentiated. If the temperature difference between the optical card 1 and the inside of the device is large, the temperature near the optical card 1 is not stable and continues to change. When the temperature between the optical card 1 and the inside of the device approaches equilibrium, the temperature change becomes smaller and the differential output approaches zero. It is detected when the differential output value becomes close to 0 and below a certain level L. For example, temperature compensation is performed when the temperature difference becomes small, such as at point A.

That is, when the differential output is smaller than L, the compensation value is supplied to the operational amplifier 5 by the compensation function determining means 4, and a semiconductor laser drive signal is obtained by adding the compensation value to the output value of the laser drive circuit 6.

On the other hand, when the differential output is larger than L, the switching signal is not outputted from the switching generation circuit 11, so that the output of the laser drive circuit 6 is not added to the operational amplifier 5 by the compensation function determining means 4, and the output of the laser drive circuit 6 is output to the semiconductor laser 12.
It is output to .

Note that the switching signal generating circuit 11 may be constructed of a comparator that detects the L level.

[Effects of the Invention] As described above, the present invention performs temperature compensation using the irradiation light intensity regarding the temperature characteristics of the optical card only when the difference between the temperature of the optical card itself and the temperature inside the device becomes small. Improve recording characteristics on optical cards by optimizing light intensity,
It becomes possible to improve the reliability of the device.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an apparatus according to a first embodiment of the present invention, FIG. 2 is a schematic diagram of an apparatus according to a second embodiment of the present invention, and FIG. 3 is a differential circuit for converting the output of a temperature sensor. FIG. 4 is a circuit diagram illustrating a conventional example. 1... Optical card 2... Transport means 3... Temperature sensor 4... Compensation function determining means 5... Operational amplifier 6... Laser drive circuit 7... Counter circuit 8... Insertion detection Sensor 9...Controller 10...Compensation value setting circuit 11...Switching signal generation circuit 12...Semiconductor laser Fig. 3

Claims (1)

[Claims] 1. In an optical recording and reproducing device that records and reproduces information by irradiating a light beam onto a recording medium, there is a means for detecting the internal temperature of the device, a means for controlling the light intensity of the light beam based on the detection output, and a means for controlling the light intensity of the light beam based on the detection output. 1. An optical recording/reproducing device comprising: means for determining whether or not a beam is used for controlling the amount of light.