JPH02105343A - Optical information recording/reproducing device - Google Patents

Abstract

PURPOSE:To reproduce the stable information signal by storing the reflected light quantity set previously into a light quantity memory means, and applying the pulse drive to a semiconductor laser with a repeating frequency higher than the information signal and with a duty ratio which ensures the reflected light quantity set previously with the prescribed output. CONSTITUTION:An information recording medium 6 is set to an information recording/reproducing device and an optical spot is controlled to the position of the medium 6. Thus, a drive circuit 12 applies the pulse drive to a semiconductor laser 1 in the initialized duty ratio. At the same time, a control signal 15 is inputted to a light quantity memory circuit 13 which stores successively the quantity of light sent from an information recording medium surface 7. Then the circuit 12 changes successively the duty ratio in the case the reflected light quantity stored successively in the circuit 13 is different from the set reference reflected light quantity. Then the circuit 12 applies the pulse drive to the laser 1 so that he coincidence is secured between the reflected light quantity stored in the circuit 13 and the reference reflected light quantity set previously.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field 2> The present invention relates to an optical information recording/reproducing device, and in particular to an optical information recording/reproducing device, in which light from a semiconductor radar is emitted as minute beams onto an information recording medium to record or/and record information. and an optical information recording and reproducing device for reproducing.

<Prior Art> A conventional optical information recording/reproducing device will be briefly explained using FIG. 3. The emitted light from the semiconductor radar 1 is converted into a parallel light beam by a collimator lens 2, and then passed through a polarizing beam sliver 3 and a 1/4 wavelength plate 4 to an objective lens 5.
, and an original spot is formed on the recording medium surface 7 of the information recording medium 6.

This reflected light from the recording medium surface 7 is reflected by the objective lens 5.1/
The light enters the photodetector 8 via the four-wavelength plate 4 and the polarization beam snoritter 3, and is output from the light amount detection circuit 9 to the signal processing circuit 14 as an information reproduction signal. Further, a part of the emitted light from the semi-integrated radar I enters the photodetector 10 to obtain an output proportional to the amount of emitted light, and this signal is given to the drive circuit 17 to stabilize the output of the semiconductor laser. There is.

On the other hand, when recording information, the recording information signal 16 is transmitted to the drive circuit 1.
7, the high output state of the radar is applied in response to this signal, and information bits (not shown) are formed on the recording medium surface 7 of the information recording medium 6.

In addition, since this information bit is generally a bit on the μm order, an auto-cutting sensor (not shown) is used for the system, an auto-tracking sensor is used for the system, and the objective lens 5 is directed perpendicularly to the recording medium surface 7. , is moved in the horizontal direction to control the position of the original spot.

<Problems to be Solved by the Invention> However, for each DI recording medium with a different reflectance, the reflected photoelectricity changes in proportion to the reflectance, so the loop gain of the optical spot position control system changes and becomes unstable. There were problems in that the level of the information reproduction signal fluctuated and stable reproduction was no longer possible.

This problem also occurs when the reflectance differs in each part of one recording medium.

The present invention is based on these problems, and it is possible to obtain a constant amount of reflected photoelectricity for various recording media with different reflectances or for a single recording medium having parts with different reflectances, and thus to be able to reflect the original spot position. It is an object of the present invention to provide an optical information recording and reproducing device that can perform stable control and can stably reproduce information signals.

Means 2 for Solving Problems The above object is to provide an optical information recording and reproducing apparatus that records and/or reproduces information by guiding light from a semiconductor laser onto an optical information recording medium as a small spot. The information recording and reproducing device has a light amount storage means for storing reflected photoelectricity added in advance, and a driving means for pulse-driving the semiconductor radar at a repetition frequency that is sufficiently higher than that of the information signal, and has a predetermined peak output. And, is the entire semiconductor radar at a duty ratio such that the predetermined reflected photoelectricity is obtained?
This is achieved by providing an optical information recording/reproducing device characterized by pulse drive.

<Embodiment> FIG. 1 is an explanatory diagram showing an embodiment of the present invention, and the embodiment of the present invention will be described below based on the figure.

In addition, in the same figure, components having the same functions as those of the conventional example shown in FIG. 3 are denoted by the same numbers, and explanations thereof will be omitted. In this embodiment, it is assumed that the reflectance is uniform throughout the entire portion of one information recording medium.

13 is a light amount storage circuit. An information recording and reproducing device has a predetermined standard for an appropriate amount of reflected light, and when the information recording and reproducing device receives the reflected photoelectricity, stable optical control, position control, information signal reproduction, etc. are possible. . This reference reflected light amount is stored in advance in the light amount storage circuit 13.

Furthermore, in response to input of the control signal 15, the light amount storage circuit 13 also stores the successive reflected light amounts input from the light amount detection circuit 9 during operation of the information recording/reproducing apparatus.

Reference numeral 11 denotes a peak output detection circuit which can detect the peak output of the semiconductor radar 1 by inputting the output of the photodetector 10.

Reference numeral 12 denotes a drive circuit which pulse-drives the semiconductor radar 1 at a repetition frequency that is sufficiently higher than the frequency of the information signal. In addition, the duty ratio of the light-emitting part of the main pulse drive of the semiconductor radar 1 can be changed so that the reference reflected light quantity and the sequentially reflected photoelectric charge are compared and the sequentially reflected photoelectric charge matches the reference reflected light quantity. It has become. Furthermore, a photodetector 10 receives a portion of the light emitted from the semiconductor radar 1.
Using the output of the semiconductor laser 1, the semiconductor laser 1 is driven so that the output of a peak output detection circuit 11 that detects the peak output of the semiconductor laser 1 at that time becomes constant.

Next, the operation during reproduction of this embodiment having the above-described configuration will be explained.

1' The information recording medium 6 is set in the information recording and reproducing device, and the original spot is controlled to a predetermined position on the surface of the information recording medium (here, the predetermined position refers to a non-recorded part or an unrecorded part). Then, the drive circuit 12 pulse-drives the semiconductor radar 1 at the initially set duty ratio.

At the same time, the control signal 15 is input to the light amount storage circuit 12, and the light amount storage circuit 12 stores information on the information recording medium surface 7 at that time.
The amount of light reflected from the camera is sequentially memorized.

Then, when the amount of sequentially reflected light stored in the light amount storage circuit 13 is different from the assumed reference amount of reflected light, the drive circuit 12 sequentially changes the duty ratio and drives the semiconductor radar 1 at a constant rate. The sequential reflection amount at that time stored in the light amount storage circuit 13 is made to match the reference reflected light amount assumed in advance.

Then, the duty ratio when the amount of sequentially reflected light and the reference amount of reflected light match is set as the duty ratio of the information recording medium, and thereafter, the semiconductor radar 1 is driven in a normal manner using that duty ratio.

The drive circuit 12 pivotally controls the semiconductor laser 1 based on the output information of the peak output detection circuit 11 so that the peak output of the semiconductor laser 1 remains at a predetermined constant value throughout the above period.

The above operation will be explained in more detail using graphs. Second
The figure is a graph showing the relationship between the reflectance of the information recording medium 6 and the duty ratio of the pulse drive of the semiconductor radar I. Here, it is assumed that the reference amount of reflected light is 0.05, and the peak output that is controlled by the drive circuit 12 is 0.4.

First, it is assumed that an information recording medium with a reflectance of 0.25 is attached to an information recording/reproducing apparatus ((&) in the same figure). At this time, according to the above operating procedure, the semiconductor laser 1 is first driven for 9 seconds at the initially set duty ratio, and the amount of reflected light is compared with the reference amount of reflected light, and the duty is sequentially adjusted so that they match. The ratio is changed and finally a duty ratio of 0.5 is determined.

That is, when a duty ratio of 0.5 is determined, the peak output is 0.4, so the effective output is 0.2, and the amount of reflected light is (effective output) x (reflectance), so 0. 2
X O,25=α05.

Next, assume that an information recording medium with a reflectance of 0.5 is loaded into the information recording/reproducing apparatus (FIG. 2(b)). At this time, the duty ratio is changed by the same procedure, and finally a duty ratio of 0.25 is determined.

That is, when a duty ratio of 0.25 is determined, the effective output is 0.1 since the peak output is 0.4, and the amount of reflected light is 0. IXO, 5-0,05.

In this way, for various recording media with different reflectances, 7”
By changing the , -T ratio, a constant amount of reflected light can be obtained.

Next, the operation during recording will be explained. During recording, a binarized recording signal 16 is input to the drive circuit 12. When one of the two values is input, the semiconductor radar 1
The output is controlled to a low output, and the same laser drive as in the above-mentioned reproduction is performed. When the other of the two values is input, the output of the semiconductor radar 1 is controlled to a high output to form information bits on the recording medium 6, so that the information bits are efficiently formed. No flat pulse driving is performed, but continuous driving is performed.

In this example, assuming that the reflectance in one information recording medium is uniform, after determining the duty ratio for one information recording medium, that duty ratio is used for that medium. If the reflectance differs in each part of the information recording medium, the amount of reflected light can be controlled more precisely by changing the duty ratio even within one medium.

<Effects of the Invention> The optical information recording and reproducing apparatus according to the present invention includes a light amount storage means for storing the amount of reflected light estimated in advance, and a semiconductor radar that is pulse-driven at a sufficiently high repetition frequency for the information signal. Since the semiconductor radar is equipped with a driving means and is driven in pulses at a predetermined peak output and at a duty ratio that provides a predetermined amount of reflected light, a constant amount of reflected light can be obtained and therefore a stable light spot can be obtained. Position control and information signal reproduction at a certain level can be performed.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention, FIG. 2 is a graph showing the relationship between the reflectance of an information recording medium and the duty ratio of pulse drive of a semiconductor radar, and FIG. This is an explanatory diagram showing an information recording/reproducing device. DESCRIPTION OF SYMBOLS 1... Semiconductor laser, 3... Polarizing beam splitter, 5... Objective lens, 6... Information recording medium, 8.1
0... Photodetector, 9... Light amount detection circuit, 11...
Peak output detection circuit, 12... Drive circuit, 13...
Light amount storage circuit, 14... Signal processing circuit, 15... Control signal, 16... Recording information signal. Agent Patent Attorney Bond Yamashita

Claims (1)

[Claims] In an optical information recording and reproducing apparatus that records and/or reproduces information by guiding light from a semiconductor laser as a minute spot onto an optical information recording medium, a predetermined amount of reflected light is stored in the optical information recording and reproducing apparatus. and a drive means for pulse-driving the semiconductor laser at a repetition frequency sufficiently higher than that of the information signal, with a duty ratio such that a predetermined peak output and the predetermined amount of reflected light are obtained. An optical information recording/reproducing device characterized by driving a semiconductor laser in pulses.