JPH0546988A - Optical waveguide memory and optical reproducing device - Google Patents

Abstract

PURPOSE:To relax the mechanical accuracy required for an optical reproducing device by providing a grating at the incident section of light impressed upon information pits. CONSTITUTION:An optical beam made incident to the incident section of an optical waveguide memory 10 composed of two clad sections 12 and a core section 13 provided with information pits 14 is led into the memory 10 through a grating 11 provided in the incident section. Even when the incident angle and incident position of the optical beam deviate more or less, the optical beam is surely and efficiently led into the memory 10, because the influence of the deviation to the optical coupling through the grating 11 is small. Therefore, when this memory 10 is used for an optical reproducing device, the mechanical accuracy required for the reproducing device can be relieved, since the reproduction is not affected much even when the incident angle and incident position of the optical beam deviate more or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical waveguide memory and an optical reproducing device for reproducing information recorded in the optical waveguide memory.

[0002]

2. Description of the Related Art In recent years, an optical recording / reproducing apparatus for optically recording / reproducing information such as code data, video information, audio information, etc. has been developed. In particular, an LD (laser disk) device for reproducing video information is used. A CD (Compact Disc) device for reproducing audio information is widely used.

On an optical disk used in this type of apparatus, video information is FM-modulated and then recorded as pit irregularities corresponding to a modulation signal, and an audio signal is converted into a digital signal, which is suitable for recording. After being modulated into a signal, it is recorded as unevenness of pits corresponding to this modulated signal.

FIG. 6 shows an example of an optical disc. The optical disc shown in the figure is a part of which is cut away for ease of explanation. Further, FIG. 7 is an enlarged view of portion B of FIG.

A large number of information pits are formed on the disk substrate 80.
81 are arranged in the circumferential direction. When reading information from this optical disc, a focused spot of laser light is applied onto the disc and traced along the information track of the disc. The intensity of the light reflected from the disk during this trace changes depending on the presence or absence of the information pit 81. Therefore, the recorded information can be reproduced by detecting the change in the light intensity with the detector.

FIG. 8 shows a specific example of an optical reproducing apparatus using this type of optical disk. The optical disc 77 is a CAV (Consta
nt Angular Velocity: constant rotation angle method or CLV
It is rotated by a spindle motor 78 based on the (Constant Linear Velocity) method. The laser light emitted from the laser light source 70 is collimated by the collimator lens 71, reflected by the half prism 72, and focused on the optical disc 77 by the objective lens 73. Next, the laser light is reflected by the optical disk 77 and then converted into parallel light by the objective lens 73, passes through the half prism 72, and is detected.
Up to 74. The output signal of the detector 74 is amplified by the amplifier 75 and output from the terminal 76 as a reproduction signal. This reproduction signal is further demodulated by a demodulator into a video signal or an audio signal. In this type of optical regenerator, one to three light beams are usually used, but only one of them is used for information detection.

[0007]

By the way, development of digitization of video signals is being advanced from the viewpoint of high image quality. When digitizing a video signal (NTSC signal), the sampling frequency is 14.3 MHz (4 fse
If c) and the number of quantization bits is 8 bits, the required transfer rate is 114 Mbit / sec. Current L
When digital recording is performed by the D device, the obtained transfer rate is about 20 Mbit / sec. Therefore, in order to digitally record the video signal in the LD, the band compression of the video signal is performed to reduce the amount of information, or the LD player is multi-beamed and a plurality of light beams are used for reading information. It is necessary to increase the information read rate. However, a dedicated processor is required for band compression of the video signal, and high processing speed and high throughput are required. Therefore, there is a problem that the system becomes large and the cost also increases. In addition, when the multi-beam is used, the structure of the player becomes complicated and the recording time is shortened.

In order to solve these problems, the inventor of the present invention previously applied for an invention relating to an optical reproducing device for an optical waveguide memory. According to this, a plurality of detectors for respectively detecting a plurality of scattered lights scattered from each information pit of the optical waveguide memory of the light beam incident on the optical waveguide memory, and a detector responding to the scattered light It is possible to provide an optical reproducing device provided with a reproducing means for collectively reproducing the information recorded in the optical waveguide memory based on the detection signal outputted from the optical reproducing device.

However, in this type of apparatus which simultaneously reproduces a large amount of data at high speed, there is a problem that high mechanical accuracy is required for its reliability.

Therefore, the present invention provides an optical waveguide memory capable of relaxing the mechanical precision required for the optical reproducing apparatus and reading information at high speed, and an optical reproducing apparatus for the optical waveguide memory. Is.

[0011]

According to the present invention, there is provided an optical waveguide memory in which an information pit is formed and a grating is provided at an incident portion of light applied to the information pit.

Further, according to the present invention, a first detector for detecting the reflected light from the grating of the optical waveguide memory and a plurality of scatterings scattered from each information pit of the light beam incident on the optical waveguide memory. Position correction of the plurality of second detectors for detecting light and the plurality of second detectors based on the detection signal output from the first detector in response to the reflected light from the grating. There is provided an optical reproducing device provided with a position correcting means for performing.

[0013]

The light beam incident on the incident part of the optical waveguide memory is guided to the inside of the memory by the grating provided on the incident part. At this time, even if the incident angle and the incident position of the light beam are slightly deviated, the influence of the optical coupling due to the grating is small, and the light beam is reliably and efficiently guided into the optical waveguide memory.

Further, in the optical reproducing apparatus according to the present invention, a part of the light beam reflected by the grating of the optical waveguide memory is detected by the first detector, and based on the detection result, a plurality of information reading first light beams are read out. Position correction of the two detectors is performed. Specifically, by determining the voltage level of the detection signal responding to the reflected light from the grating, the entire first and second detectors are moved in an appropriate direction to perform the position correction. ..

[0015]

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

FIG. 1 shows a sectional view of an embodiment of the optical waveguide memory according to the present invention.

The optical waveguide memory 10 has two clad portions 12
And a core portion 13 including information pits 14 sandwiched between these clad portions, and the grating 11 is provided inside the clad portion 12 along the vicinity of the end of the side surface of the optical waveguide memory 10. There is. The grating 11 is formed by arranging a large number of discontinuities of refractive index side by side at equal intervals of submicron to micron order.

The optical waveguide memory 10 has a tape-like shape, and information is recorded in the information pits in the core portion 13 of the optical waveguide memory 10.
Recorded as the presence or absence of 14. That is, the presence or absence of the refractive index discontinuity in the core portion 13 of the optical waveguide memory is arranged according to the information to be recorded.

Since the optical waveguide memory 10 according to the present embodiment is provided with the grating 11, when it is used in the optical reproducing apparatus, even if the incident angle and the incident position of the light beam are slightly deviated, these are reproduced. Has a small effect on. In addition, the coupling of laser light by the grating 11 has high optical transmission efficiency. Therefore, high stability in signal reproduction can be obtained, and the mechanical accuracy required for the optical reproduction device can be relaxed.

In the present embodiment, the optical waveguide memory 10 has a tape shape, but this is merely an example, and the shape of the optical waveguide memory is not limited to the tape shape.

The grating 11 is composed of a large number of refractive index discontinuities, but is not limited to this as long as the desired performance can be obtained.

Next, an embodiment of the optical reproducing apparatus according to the present invention will be described with reference to the drawings.

FIG. 2 shows a case where the above-mentioned optical waveguide memory is used for an optical reproducing device, and FIG. 3 is a sectional view of FIG.

The optical system of the light reproducing device comprises a laser light source 20, a collimator lens 21, and an objective lens 22. This optical system consists of an objective lens 22, a collimator lens 21, a laser light source on top of the optical waveguide memory 10 from the side closest to the memory.
It is installed in the order of 20. Further, the photodetection section 23 is arranged adjacent to the side surface of the optical waveguide memory, adjacent to the side surface of the optical waveguide memory 10, and parallel to the side surface of the optical waveguide memory 10.

A plurality of (n) detectors 30, which are the second detectors, which constitute the photodetection section 23, are arranged in a linear array, and each detector 30 has an amplifier (not shown). )
The amplifier circuit 32 is connected via. The output terminal 33 is connected to the amplifier circuit 32.

In the photodetection section 23 installed facing the side surface of the optical waveguide memory 10, a detector 31, which is a first detector, is further provided at a position substantially facing the grating 11 of the optical waveguide memory 10. It is equipped. An amplifier circuit 34 is connected to the detector 31 via an amplifier.

The entire detector 30 is composed of a CCD (charge coupled device) linear sensor having a high sampling frequency, and the detector 31 is composed of a photo-detecting element such as a photodiode.

A driving device 40 having a function of translating the light detecting portion 23 along the side surface of the tape-shaped optical waveguide memory is mechanically connected to the light detecting portion 23. A broken line connecting the drive device 40 and the photodetection unit 23 in FIGS. 2 and 3 indicates a connecting means connecting the drive device 40 and the photodetection unit 23. The drive device 40 is also electrically connected to receive a control signal from the control device 41. The control device 41 receives the output signal of the amplification circuit 34 as an input for control. The drive device 40 and the control device 41 correspond to position correction means for performing the position correction of the photodetection unit 23.

The laser light emitted from the laser light source 20 is collimated by the collimator lens 21 and focused by the objective lens 22 on the grating 11 on the end face of the tape of the optical waveguide memory 10. The laser light is deflected by the grating 11 and travels in the core portion 13 inside the optical waveguide memory 10. The laser light incident on the inside of the optical waveguide memory 10 is
A part of it is scattered by each information pit 14 and the optical waveguide memory
It goes out from the side of 10. The scattered light is detected by the photodetector 23 having a plurality of detectors, converted into an electric signal, and then output from the terminal 33 as a reproduction signal via the amplifier circuit 32.

The above-mentioned tape-shaped optical waveguide memory 10 in this embodiment is constructed so as to move in the direction of the arrow in FIG. 2. Therefore, laser light is sequentially incident on the core portion of the optical waveguide memory 10, The laser light is scattered by each information pit, the information pit is detected by this, and the information is collectively read.

A part of the laser light incident on a part of the grating 11 is reflected by the grating 11 and detected by the detector 31. An amplifier circuit 34 is connected to the detector 31. When the laser light enters the detector 31, a voltage signal having a signal level corresponding to the detected light intensity is output from the amplifier circuit 34 via the amplifier, and the control device 41
Entered in. The control device 41 controls the driving device 40 based on the input signal of the amplifier circuit 34, and corrects the position of the photodetection unit 23.

FIG. 4 shows the details of the photo-detecting section 23.

The current signal output from each of the detectors 30 arranged in a linear array is converted into a voltage signal by the amplifier 35 and output to the amplifier circuit 32. The voltage signal is amplified by the amplifier circuit 32 and then output from the terminal 33. Similarly, in the detector 31, the current signal is converted into a voltage signal by the amplifier 36 and then amplified by the amplifier circuit 34.

A flow chart of the position correction procedure is shown in FIG. The position correction processing by the position correction means will be described with reference to this figure.

The position correction is executed by a command from the control device 41. First, the voltage signal level output from the amplifier circuit 34 is determined (step S1). If the voltage signal level V1 is lower than the reference value V0, the photodetection unit 23 is translated by the driving device 40 in a small step (Δy) in the y-axis direction in FIG. 2 (step S2). Next, it is determined whether or not the voltage signal level V2 after the movement is equal to or higher than the reference value V0 (step S3). As a result, if it exceeds the reference value, the position correction is completed, and the position correction means waits for a predetermined time. (Step S7) or steps S1 to S3 are repeated. On the other hand, when it does not exceed the reference value, it is determined whether or not the current signal level is higher than the previous signal level (step S4), and the process is divided into the following two steps. When the signal level rises (V2> V1),
The translational movement is continued in the same direction (step S5). When the signal level is equal to or lower than the previous value (V2 ≤ V1), a small step in the direction opposite to the first translational movement (if the front is Δy,-
y, if the front is −Δy, Δy) is translated (step
S6). Hereinafter, steps S3 to S5 are continuously performed until the reference value is exceeded, and if the reference value is exceeded, the step
After S7, the position correction process is repeated from step S1.

In this position correction process, it is assumed that the voltage signal level of the detector exceeds the reference value within the maximum movable range of the photodetector 23. In addition, translational movement in the x-axis direction and the z-axis direction may be performed as necessary.

In the optical reproducing apparatus according to the present embodiment, the plurality of scattered lights from the information pits are detected by the detectors 30 at the corresponding positions, so that a plurality of digital information can be read out at once. The number of channels of signals that can be reproduced collectively is the same as the number of detectors 30, and therefore, by increasing the number of detectors, the information read rate can be greatly improved.

Based on the output signal of the detector 31, the photodetector
Since the position correcting means for performing the position correction of 23 is further provided in the optical reproducing device, the optical waveguide memory 10 can be accurately tracked.

Further, by temporarily storing the reproduction signal output from the terminal 33 in the buffer and reading it as needed, it is possible to continuously reproduce the signal at a constant rate.

In this embodiment, the detectors 30 are arranged in a linear array, but the detectors may be arranged in a matrix so that all the detectors detect scattered light from the optical waveguide memory. Is also possible.

A CCD was used as the detector 30 as a whole, but other types of detectors having equivalent performance may be used instead. Further, the detector 31 may be configured as a part of the entire detector 30, and in this case, for example, the detector 31 may be configured of a part of the elements forming the CCD.

The position correcting means is not limited to this embodiment, and various algorithms and driving devices are applied.

[0043]

Since the optical waveguide memory according to the present invention is provided with the grating in the light incident portion, when the information recorded in the optical waveguide memory is reproduced by the optical reproducing device, the incident angle and the incidence of the light beam are incident. Even if the position is slightly deviated, the influence on reproduction is small. Therefore, high stability can be obtained in the signal reproduction, and the mechanical accuracy required for the reproducing apparatus can be relaxed.

In the optical reproducing apparatus according to the present invention, the reflected light from the grating of the optical waveguide memory having the grating in the light incident portion is detected, and the position correcting means detects a plurality of detectors for reading information based on the detection result. Since the position correction is performed, accurate tracking of the optical waveguide memory is realized. As a result, a digital image optical reproducing device for accurately reading information at high speed can be realized, and a large-capacity, high transfer rate reproducing system corresponding to a high-definition image such as a high-definition system in the future can be realized.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of an optical waveguide memory for an optical reproducing device according to the present invention.

FIG. 2 is a configuration diagram of an embodiment of an optical reproducing device according to the present invention.

3 is a cross-sectional view of the optical reproducing device of FIG.

FIG. 4 is a configuration diagram showing in detail a photo-detecting section that constitutes the optical reproducing apparatus of FIG.

FIG. 5 is a flowchart showing the processing by the position correction means of the optical reproducing apparatus according to the present invention.

FIG. 6 is a perspective view of an optical disc used in a conventional optical reproducing device.

FIG. 7 is an enlarged view of a part of the optical disc of FIG.

FIG. 8 is a block diagram of an example of a conventional optical reproducing device.

[Explanation of symbols]

 10 Optical waveguide memory 11 Grating 12 Cladding section 13 Core section 14 Information pit 20 Laser light source 21 Collimator lens 22 Objective lens 23 Photodetector section 30, 31 Detector 32, 34 Amplifier circuit 33 Terminal 35, 36 Amplifier 40 Drive unit 41 Controller

Claims (2)

[Claims] 1. An optical waveguide memory having information pits formed therein, wherein an optical waveguide memory is provided with a grating at an incident portion of light applied to the information pits of the optical waveguide memory. 2. A first detector for detecting reflected light from the grating of the optical waveguide memory according to claim 1, and a light beam incident on the optical waveguide memory scattered from each information pit. A plurality of second detectors for detecting a plurality of scattered lights, and a plurality of the second detectors based on the detection signal output from the first detector in response to the reflected light from the grating. An optical regenerator comprising a position correcting means for correcting the position of the detector.