JPS5927972B2 - optical information detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention irradiates a light beam onto a disc on which information such as video and audio signals is recorded with an information track consisting of an uneven surface, and detects the information by the reflected light of this light beam. The present invention also relates to an optical information detection device that detects a signal of the distance between a converging lens and a disk.

Conventionally, there is a device that detects an information signal, a tracking signal, and a distance control signal between a convergence range and a disk using a single light beam. In this device, when a light beam is irradiated obliquely to a disk and the distance between the converging lens and the disk changes relative to the reference distance, the reflected light from the disk will be reflected when the converging lens and the disk are at the reference distance. The distance control signal was obtained from the reflected light by utilizing the deviation of the reflected light. However, in this case, when the light beam is irradiated obliquely to the disc, the beam spot formed on the disc is distorted and becomes non-circular, which poses a problem in achieving good recording and reproduction. In view of the above points, the present invention provides optical information that does not cause distortion of the beam spot with respect to the disk, detects information signals and interval control signals with a single light beam, and enables good information reading. The purpose is to provide a detection device.

Embodiments of the present invention will be described below based on the drawings.

As shown in FIG. 1, the disk 1 has a spiral information track 3 formed by intermittent bits 2 recessed with a constant width and a constant depth on the back surface. As is well known, the information signal is recorded by modulating the length of the bits 2 and the length between the bits, and the disk 1 rotates at a constant speed above the turntable. To read the information, the pick-up device A is moved in the radial direction of the disc 1 at a constant speed by a motor (not shown). This pickup device A has a diaphragm device 6 on the top of a frame 4 for converging the light beam 5 onto the disk 1, and a deflection device T for deflecting the light beam 5 inside.
), a beam generator 8 that generates a light beam 5, a differential photoelectric element 9 that receives reflected light from the disk 1, and the like. The diaphragm device 6 has a base 6a fixed to the frame 4, and a cylinder 6b having a built-in converging lens 10 is movably converged vertically.
A four-segment photoelectric element 1 having a through hole Ila concentrically with
1 is fixed to the base. To explain in more detail with reference to FIG. 2, the optical axis 10a of the converging lens 10 is arranged perpendicularly to the disc 1 and is fixed to the cylindrical body 6b. Convergent lens 10
A light beam 5 enters the entire opening of the converging lens 10 from below so that the optical axis 10a and the central axis 5a coincide, and this light beam 5 is focused by the converging lens 10 to form the disk 1. It converges as a minute spot on the top. Therefore, if the light beam 5 is not diffracted on the disk 1, the reflected beam will form the same conical outer peripheral surface 5b as the incident beam and will return to the deflection device 7 via the converging lens 10 again, but the bit 2 When the light beam 5 is diffracted by the converging outer circumferential surface 5b, the light beam 5 is reflected to the outside. Therefore, photoelectric element 1
1 is arranged along the converging outer circumferential surface 5b in order to detect only the above-mentioned diffracted light. In this embodiment, the photoelectric element 11 is a four-part element having the through hole 11a in the center, and the through hole 11
A is fixed to the base 6a between the disk 1 and the converging lens 10, the circumferential portion of which substantially coincides with the convergent outer circumferential surface 5b, and the light receiving surface is arranged parallel to the disk 1, as shown in FIG. Similarly, the light receiving surface of the photoelectric element 11 may be arranged perpendicularly to the outer peripheral surface of the convergence of the light beam, or the photoelectric element 11 and the converging lens 10 may be fixed to the movable cylinder 6b. In the former case, the light-receiving surface of the photoelectric element 11 can be provided closer to the converging outer circumferential surface, so that the photoelectric element having the same light-receiving surface can detect diffracted light over a wider range, especially diffracted light near the converging outer circumferential surface. 5b can be received, and delicate control signals can be obtained. In the latter case, disk 1
The positional relationship between the converging lens 10 and the photoelectric element 11 is the disk 1.
Since the photoelectric element does not change due to vibration or the like, a reliable signal can be obtained from the photoelectric element. Such a four-division photoelectric element 11 is used to detect information signals and tracking signals.

That is, the photoelectric element 11 has four light receiving elements 11b, 11c,
It consists of 11d and 11e and has two separation zones,
One separator is parallel to information track 3 and the other is disk 1.
parallel to the radial direction. The diffracted light 5b at the side edge of the bit 2 is mainly divided into two light receiving element groups 11b and 11c by a separation zone parallel to the information track 3.
This difference output is detected as a tracking signal, and the diffracted light 5b at the front and rear ends of the bit 2 is mainly divided by a separation zone parallel to the radial direction of the disk 1. An output difference is generated between two sets of two light receiving element groups 11b, 11e and 11c, 11d, and this difference output is detected as an information signal.

On the other hand, the focus signal for keeping the minute spot of the light beam 5 on the disk 1 at a constant diameter, that is, the distance control signal between the disk 1 and the converging lens 10, is generated by a differential photoelectric element separately provided in the frame 4. 9.

That is, out of the reflected light from the disk 1, the light that is not diffracted passes through the through hole 11a of the photoelectric element 11, is deflected again by the deflection device 7, and is separated from the optical path of the incident light beam by the reflector 12 and provided separately. The differential photoelectric element 9 is irradiated. Now, when the distance between the disk 1 and the converging lens 10 changes due to the vibration of the disk 1, and the diameter of the minute spot on the disk 1 changes, the fourth
As shown in the figure, the reflected beam 5c is deflected and the irradiation spot on the differential photoelectric element 9 moves. Therefore, by detecting the differential output of the differential photoelectric element 9, the cylindrical body 6b can be moved up and down together with the converging lens 10, and the interval can be controlled. In this case, the reflector 12 will partially block the light beam 5 entering the deflection device 7, but the image of the reflector 12 will be
Reflector 12 is placed at a position where it is connected away from the convergence point above.
, there is no significant influence on the light quantity distribution of the light beam 5. The present invention is as described above, and in particular, the optical axis of the convergent lens is arranged substantially perpendicular to the disk, the optical axis and the center line of the light beam are made to coincide with each other, and the light beam is incident on the convergent lens, and the disk is A reflector is arranged so as to converge a minute spot on the top and take out the light beam of the deflected part of the reflected light from the disk of the light beam, and the optical path of the deflected reflected beam taken out by this reflector is Because the differential photoelectric element is installed, there is no distortion of minute spots on the disc, and good information can be read.Accurate information signals and interval control signals can be detected with a single light beam. This has effects such as simplifying the structure of the entire device.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the overall structure of an embodiment of the present invention, FIG. 2 is an explanatory diagram showing a photoelectric element and a converging outer peripheral surface, and FIG. 3 is an explanatory diagram of another embodiment showing the same relationship as FIG. 2. , FIG. 4 is an explanatory diagram of the optical system of this embodiment viewed from above FIG. 1.

Claims (1)

[Claims] 1 A light beam 5 is irradiated via a converging lens 10 onto a disc 1 on which information such as video and audio signals is recorded with an information track 3 consisting of an uneven surface, and the reflected light of this light beam 5 is received by a photoelectric element 11. In the apparatus for reading the information by optical change of reflected light, the optical axis 10a of the converging lens 10 is disposed substantially perpendicular to the disk 1, and the optical axis 10
a and the center line 5a of the light beam 5 are made to coincide with each other, the light beam 5 is incident on the converging lens 10, and a minute spot is converged on the disk 1. A reflector 12 is disposed so as to extract the light beam of the deflected portion, and a differential photoelectric element 9 is disposed in the optical path of the deflected reflected beam 5c extracted by the reflector 12. An optical information detection device that detects a signal corresponding to the distance between the converging lens 10 and the disk 1.