JPS5935091B2 - optical information reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical information reading device that irradiates a light beam onto a disc on which information such as video or audio signals is recorded in optical form and reproduces information from the modulation received by the light beam.

In recent years, this type of device has been miniaturized by various means.

For example, extremely small semiconductor lasers have been used in place of helium-neon tubes as light beam generators, and light beam tracking control devices, focus control devices, and the like have also been miniaturized. However, as a comprehensive reading device that combines information reading with the above-mentioned tracking control and focus control driving device, miniaturization is still insufficient. It is becoming difficult to reduce the thickness. In view of the above points, it is an object of the present invention to provide an optical information reading device that appropriately arranges the optical path, focus control system, tracking system, etc., and allows the entire device to be made smaller, especially thinner. It is an object.

Examples will be described below based on the drawings.

The first frame 1 is formed by hollowing out a block body,
The first hole 1a drilled in the vertical direction has a second frame 4 which holds the converging lens 2 in the upper part and has a bobbin 3a and a solenoid 3b which are the operating body 3 of the electromagnetic drive device A in the lower part. The second frame 4 is vertically movably suspended from the first frame 1 by dampers 5 and 6.

The first frame 1 has a horizontal second hole 1b and a third hole 1c.
A second hole 1b communicates with the center of the first hole 1a, and a third hole 1c intersects with the second hole 1b at right angles. A cylinder 9 to which a semiconductor laser as a light beam generator 7 and a coupling lens 8 are fixed is fitted into the end of the second hole 1b, and a λ/4 plate 10 is fitted near the first hole 1a. A light-receiving element 11 consisting of a four-segment differential photodiode is fixed at the end of the third hole 1c, and a holder 15 is further fixed with a lens 12, a light shielding plate 13, and a polarizing beam splitter 14. is inserted. Therefore, the optical elements D forming the incident optical path, that is, the coupling lens 8 of the light beam generator T1, the polarizing beam splitter 14, and the λ/4 plate 10 are arranged on a straight line in the horizontal direction.
The optical elements E forming the reflected optical path, that is, the polarizing beam splitter 14, the lens 12, the light shielding plate 13, and the light receiving element 11 are arranged on the same horizontal plane on a straight line perpendicular to the incident optical path. The cylindrical body 9 is attached with a screw 16 from the side.
The position can be adjusted in the optical axis direction or rotational direction by loosening the screw 16.
Since a retaining ring 17 is fixed to the fourth plate 10 by a screw 18, the position in the rotational direction can be determined by loosening the screw 17, inserting a pin through the working hole 19, and rotating the retaining ring 17. The position of the light receiving element 11 can also be adjusted using the screw 20. As shown in FIG. 8, the holder 15 has a needle-shaped tip 15a that abuts the bottom of the third hole 1c, holds the polarizing beam splitter 14 in a through groove 15b in the center, and has a rear end 15c. It is formed into a cylindrical shape, and the lens 12 for shortening the optical path and a compression spring 21 are housed in this cylinder.
A screw 22 is brought into pressure contact with the bottom of the hole 1c, and a screw 22 is brought into elastic contact with the outer periphery of the cylindrical rear end 15c from one side, and another compression spring 23 is brought into elastic contact from the other side.
5 as a whole to enable position adjustment of the lens 12, the light shielding plate 13, and the polarizing beam splitter 14. Further, the first frame 1 is provided with electromagnetic drive devices A, B, and C for focus control, tracking control, and jitter control.

A magnet 24 is attached to the lower part of the first hole 1a, and the magnet 24 has a central protrusion 24a inside the solenoid 3b and an outer periphery 24b outside the solenoid 3b, and the magnet 24 is attached to the focal point together with the bobbin 3a and the solenoid 3b. It forms an electromagnetic drive device A for control. A mirror 25 that takes in the light beam from the light beam generator 7 and makes it enter the converging lens 2 is fixed on the top of the central protrusion 24a. 2
It is always fixed in the hollow part of the frame 4. Further, on the side of the first frame 1, actuating bodies 26 and 27 of two electromagnetic drive devices B and C are provided for operating the first frame 1 in directions perpendicular to each other on a horizontal plane. That is, the operating body 26,
27 consists of a bobbin and a solenoid like the actuating body 3, one of the actuating bodies 26 has an axis parallel to the axis of the incident light beam on the horizontal plane, and the other actuating body 27 has an axis parallel to the axis of the incident light beam on the horizontal plane. It has orthogonal axes. and the actuating body 26,2
The magnets 28 and 29 for 7 are fixed to a base 30 that supports the first frame 1, and the base 30 supports the first frame 1 with three elastic pins 31 as shown in an enlarged view in FIG. is supported. Therefore, tracking and jitter correction are performed in two directions on the horizontal plane within the range of elasticity of the pin.
This is done by moving. In this embodiment, the electromagnetic drive device B moves the first frame 1 in the optical axis direction of the incident light beam to perform jitter correction, and the electromagnetic drive device C moves the first frame 1 in the optical axis direction of the reflected beam. Although tracking control is performed by moving the pin 31, it is also possible to perform tracking control in only one direction, and in this case, instead of the pin 31, a plate-shaped elastic body 32 as shown in FIG. can be used. In addition, in this embodiment, I magnetic drive device B
, C (pressing central axis when pressing the first frame 1)
is shifted from the moving direction of the first frame 1, but this is because it presses near the center of gravity of the unitized part of the first frame 1 to prevent unnecessary rotation of the first frame 1. It is for. Furthermore, through holes 33 are provided in the side walls of the base 30 and the first frame 1.
, 34 are drilled, which are the electromagnetic drive devices A, B,
This is the electrical lead wire extraction hole to C. Further, in the electromagnetic drive device A for the focal point @1 leg, stamped or etched metal plates are used as the dampers 5 and 6. This is because in a damper with an extremely small diameter like this example,
This is because conventional members such as cloth or net impregnated with resin and bent cannot obtain sufficient properties, so in this example, as shown in Fig. 9, metal punched in three stages in the radial direction was used. using a board. Next, the optical system of this example will be explained.

The light beam 35 emitted from the semiconductor laser light beam generator 7 has its beam diameter adjusted by the coupling lens 8, passes through the polarizing beam splitter 14, passes through the λ/4 plate 10, and is deflected in the vertical direction by the mirror 25. Ru.

This light beam 35 is then passed through the converging lens 2 to the disk 3.
A minute beam spot 37 is formed on the disk 3.
After being reflected by the converging lens 2 and the mirror 25
is retrieved via. Further, since the light beam 25 is polarized again by the λ/4 plate 10, the light beam 25 is polarized by the next polarizing beam splitter 14.
Then, the light is totally reflected and deflected in the right angle direction, passes through the lens 12, passes through the light shielding plate 13, and is irradiated onto the light receiving element 11. The information recorded on the disk 36 indicates that the total amount of light received by the 4-division differential photodiode, which is the light receiving element 11, is
The focal point is detected by changing the information pit on the disk 36, and when the relative position between the disk 36 and the converging lens 2 changes and the diameter of the bead spot 37 changes, the focus is detected by being blocked by the light blocking plate 13. The light beam 35, which is not
The tracking detection for tracking the information track 38 is performed by moving to the set of light receiving surfaces 11a, 11c, 11b, 11b, The jitter correction obtained from the difference in the amount of light received with the group 11d and the time shift in the information track direction is electrically extracted from the signal containing the information. The present invention is as described above,
Tracking control is performed by moving the first frame itself.
Unlike the case where the light beam is deflected by a rotatable mirror, there is no need for a special optical system to remove tracking effects from the light beam returning to the photodetector, and the optical system can be simplified and Only the second frame moves, and the mirror for introducing the light beam into the converging lens is located between the converging lens and the operating body, and the incident optical path and reflected optical path are arranged in the horizontal direction. Therefore, it is possible to provide a device with a thin vertical thickness.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional plan view of an embodiment of the present invention, and FIG.
3 is a plan view, FIG. 4 is a front view, FIG. 5 is a partial sectional view showing the engagement relationship between the first frame and the base, and FIG. Figure 6 is a perspective view of the elastic body, Figure 7
The figure is a perspective view of the λ/4 plate retaining ring, Figure 8 is a perspective view of the polarizing beam splitter holder, Figure 9 is a perspective view of the damper, and Figure 10 shows the relationship between the light shielding plate and the light receiving element. FIG. 11 is a front view of the optical system of this embodiment, and FIG. 12 is a plan view of the optical system. 1...First frame body, 2...Convergent lens,
3... Working body, 4... Second frame body, 7...
...Light beam generator, 11 ... Light receiving element, 25 ... Mirror 35 ... Light beam, 36 ... Disk, 37 ... ...Beam spot, 38...Information track, A...
...Electromagnetic drive device, D...Optical element in the incident optical path, E... Optical element in the reflected optical path.

Claims (1)

[Claims] 1. The light beam 35 is irradiated onto the disc 36 on which information is recorded in an optical form, the information is read, and the disc 36 is
Focus control to keep the beam spot 37 diameter on 6 constant;
In an optical information reading device that performs tracking control for causing a beam spot 37 to track an information track 38, an optical element D in an incident optical path including a light beam generator 7
is fixed to the first frame 1 in a substantially horizontal direction, and a second frame 4 is fixed in a substantially vertical direction to the converging lens 2 for irradiating the optical beam 35 onto the disk 36 and the operating body 3 of the electromagnetic drive device A. , supported by the first frame 1 to be movable in the vertical direction, and between the converging lens 2 and the operating body 3 is fixed to the first frame 1 and deflects the light beam 35 from the incident optical path. Convergent lens 2
A mirror 25 is positioned on the first frame 1 to direct the reflected light beam from the disk 36 to the light receiving element 1.
1 is branched from the incident optical path and fixed in a substantially horizontal direction, tracking control is performed by moving the first frame 1 in the horizontal direction, and the second frame 4 is An optical information reading device that controls a focus by moving an electromagnetic drive device A in a direction perpendicular to a first frame 1.