JPH0430648Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical pickup device suitable for mounting an optical member such as a critical angle prism.

[Prior Art] In recent years, optical recording or reproducing devices that can record and reproduce information using an optical pickup (device) that utilizes a light beam have attracted attention.

When an optical pickup using the above-mentioned light beam is used, it is possible to record at a much higher density than when using a conventional magnetic head. For this reason, a control system with higher precision than before is required. For example, when it is necessary to irradiate an optical recording medium with a focused light beam in a spot-like state, and when accessing a target track,
Tracking servo means that constantly scans the track is required.

The optical pickup for maintaining the focus state is based on the critical angle method, which detects whether or not the focus state is achieved by receiving the reflected light from the recording medium with a photodetector through a prism set at a substantially critical angle. There is a focus detection method.

[Problems to be solved by the invention] In the case of an optical pick-up using the above detection method, it is difficult to install the prism, and even a slight angular deviation during the screw tightening process can cause problems in focus detection. Accuracy will be greatly reduced. For this reason, in the past, it took a lot of effort to adjust and install the prism to fix it in an appropriate state.

The present invention has been made in view of the above-mentioned points, and it is an object of the present invention to provide an optical pickup device that can be easily fixed with almost no deviation from the adjusted state when it is fixed.

[Means and effects for solving the problem] In this device, a long hole 45 is provided in the base 41 to which an optical member such as the critical angle prism 33 that is attached with fine adjustment is fixed, and the main body to which the base 41 is fixed is provided. A driver 48 with an eccentric pin 51 protruding from the side fitting hole 49
The eccentric pin 51 is inserted into the elongated hole 45 to enable fine adjustment of the mounting position or angle of the base 41, and a screw 54 is inserted loosely through the through holes 52 and 23 provided on the main body side. , 55 are screwed into screw holes 46 and 47 formed in the base 41 to form a fixing means for the optical member fixed to the base 41.

[Example] The present invention will be specifically described below with reference to the drawings.

1 to 5 relate to one embodiment of the present invention, and FIG. 1a shows a plan view of the main part of one embodiment,
Figure 1b shows an enlarged cross section taken along line B-B' in Figure 1a,
FIG. 1c shows an enlarged cross section taken along the line C-C' in FIG. 3 is a plan view of the part of the main body of the optical pickup device where the critical angle prism is attached, FIG. 4 is a fine adjustment driver, and FIG. 5 is a prism stand to which the critical angle prism is fixed. The part where the is fixed is shown enlarged.

The arrangement of the optical system of the optical pickup device of one embodiment is as shown in FIG.

A mounting hole is formed in the housing side wall of the pickup main body 2, and a laser diode 3 is fixed via a diode (mounting) frame 4. This laser diode 3 is housed in a cylindrical container, and is configured to emit laser light from a glass window on the top side of the cylinder. On the optical axis from which this laser light is emitted, via the lens frame 5,
A collimator lens 6 is attached. In this case, the lens frame 5 has a male thread formed on the inner wall on the laser diode 3 side to be screwed into the threaded part of the diode frame 4, and the other end is fitted so that it can be moved back and forth (with respect to the laser diode 3). The focal length can be adjusted. Note that the lens frame 5 can be fixed with a set screw 7.

The laser beam is made into parallel light by the collimator lens 6, and the upper surface (inner surface) of the bottom plate of the pickup main body 2
The light enters a shaping prism 9 fixed at an appropriate angle, and the elliptical light beam is shaped into a circular light beam. This circular laser beam passes through a half mirror 11, is reflected perpendicularly (upwards) to the plane of the paper by a total reflection mirror 12, and is housed on the top side of a cylindrical two-dimensional drive actuator 13 shown in FIG. 2b. The light is focused through an objective lens 14 and irradiated onto a disk 15 as a magneto-optical optical recording medium. The reflected light from the disk 15 passes through the objective lens 14, is totally reflected by the total reflection mirror 12, and is partially reflected by the half mirror 11. The reflected light is further divided into two beams in which a part is reflected by the half mirror 16 and the remaining part is transmitted. The light beam reflected by the half mirror 16 passes through the 1/2 wavelength plate 17,
After its plane of polarization is rotated, it enters the polarization beam splitter 18. The half-wave plate 17 is rotatable in a plane perpendicular to the optical axis by a holder (not shown), and is fixed to the upper surface of the bottom plate of the main body 2 with screws after adjusting the optical system. The above polarizing beam splitter 1
The light flux incident on 8 is split into two polarized components, and a condenser lens 19 provided on the split optical axis.
20 and enter photodiodes 21 and 22 as photodetectors.

The photodiodes 21 and 22 are fixed to diode substrates 23 and 24 by soldering or other means, and are moved left and right (second
In Figure a, it is possible to move within the plane of the paper including the optical axis) and is fixed with setscrews 27 and 28. (Set screw 27,
When 28 is loosened, each diode frame 23, 24 can be moved within the elongated hole in the left and right direction. ) Furthermore, the diode frames 25 and 26 are movable up and down with respect to the main body 2, and are fixed with set screws 29 and 30, so that they can be fixed in an appropriate state by adjusting the deviation of the optical axis. It's like this. Thus, the luminous flux of each polarized light component is transmitted to each photodiode 21,
22, and the signal output of each photoelectrically converted polarized light component is passed through a differential amplifier (not shown) to reproduce the signal in a differential manner. This differential method can reduce noise components and increase signal components to obtain a reproduced signal output with a good S/N ratio.

Incidentally, the light passing through the half mirror 16 is reflected by the slope 32 and enters the critical angle prism 33. In this case, when the distance between the objective lens 14 and the disk 15 surface changes, the angle at which the incident light enters the critical angle prism 33, which is set close to the critical condition, changes, and the amount of light that enters the four-split photodetector 34 changes. Focus detection is performed using this change, and focus servo can be performed using this output. A substrate 35 on which the photodetector 34 is fixed is arranged so that the position of the four-split photodetector 34 can also be adjusted in the horizontal and vertical directions.
can be fixed by adjusting the movement slightly left and right with respect to the detector frame 36, and is fixed to the detector frame 36 with a set screw 37. The detector frame 36 can also be moved up and down with respect to the side wall of the main body 2 and adjusted by tightening the set screw 3.
It can be fixed at 8.

By the way, the critical angle prism 33 is an optical member that requires delicate angle adjustment in order to perform the focus servo with a predetermined accuracy.

In this one embodiment, the critical angle prism 33
is fixed to the prism stand 41 by adhesive or other means, as shown in FIG.

The prism stand 41 has a fan-like shape, for example, and has a recess 42 formed on the back side, as shown in FIGS. The prism stand 41 to which the critical angle prism 33 is fixed can be rotated around this pin 44 as a rotation center.
(Indicated by arrow D in FIG. 1a.) The center of the recess 42 into which the top of the pin 44 is fitted (or the center of the pin 44) is the slope for critical angle detection in the critical angle prism 33, where the light beam is reflected or refracted. It is located directly below the center position.

The prism stand 41 has, for example, a long hole 45 at a position facing the center of the slope of the (critical angle) prism 33.
And screw holes 4 for set screws are provided on both sides of this elongated hole 45.
6,47 are provided. Opposed to the elongated hole 45, a circular fitting hole 49 is provided in (the bottom plate of) the main body 2 into which a fine adjustment driver 48 can be fitted, and an eccentric pin 51 is protruded from the tip of the driver 48. be. The eccentric pin 51 has an outer diameter that allows it to fit into the elongated hole 45, and when the driver 48 is rotated by an appropriate angle and fitted into the fitting hole 49, the eccentric pin 51 at its tip will fit into the elongated hole 45. When the driver 48 is rotated in this state, the side wall of the elongated hole 45 is pressed against the eccentric pin 51, and the prism base 41 is moved to the pin 44.
The mounting angle or position can be finely adjusted by rotating by a small angle around the .

Also, opposite to the screw holes 46 and 47 of the prism stand 41, through holes 52 and 53, which are larger than the screw holes 46 and 47, are provided on the main body 2 side, respectively. These through holes 52 and 53 are formed in a slightly elongated shape in a direction perpendicular to the direction connecting the center position of the through hole 43 (or pin 44), as shown in FIG.
Even if the prism stand 41 is rotated by a minute angle and the positions of the screw holes 46 and 47 are rotated and shifted, the screw holes 46 and 47 can be connected and fixed. These through holes 5
The inner diameter (width) of 2, 53 is the opposite screw hole 46, 4
Each set screw 54, 5 has a larger outer diameter than the outer diameter of 7, and loosely passes through each through hole 52, 53 from the back side of the bottom plate of the main body 2.
5 is a prism stand 4 facing each through hole 52, 53.
By screwing into the screw holes 46 and 47 of 1,
The prism 41 can be fixed to the main body 2.

Set screws 54 and 55 on the back side of the main body 2
As shown in FIG. 3, elliptical recesses 56 and 57 are formed around each of the through holes 52 and 53 through which the through holes 52 and 53 are loosely inserted, and set screws are inserted into the recesses 56 and 57 as shown in FIG. The plate portions of the setscrews 54 and 55 are housed to prevent the plate portions of the set screws 54 and 55 from protruding from the back surface of the base 8. Furthermore, a shallow elliptical recess 58 is provided on the back side of the main body 2 to cover the screw hole 46, elongated hole 45, and screw hole 47 portions.

In this embodiment, when finely adjusting and installing the prism 33, a driver 48 provided with an eccentric pin 51 is used to set the prism 33 to an appropriate fixed position,
After that, from the correct fixing position finely adjusted by screwing the set screws 54 and 55 loosely passed through the through holes 52 and 53 from the back side of the main body 2 into the screw holes 46 and 47 of the prism stand 41. It is designed so that it can be fixed without much movement.

That is, in FIG. 1c, the fitting hole 49 of the main body 2
When the driver 48 (shown in FIG. 4) is inserted and the eccentric pin 51 is inserted into the elongated hole 45 of the prism base 41 and rotated, the eccentric pin 51 will press the side wall of the elongated hole 45. The prism stand 41 can be rotated by a small angle in the direction shown by arrow D in FIG. In this manner, the prism stand 41 can be fixed with the setscrews 54 and 55 in a state where it is set at an appropriate angular position. Set screw 54 in this case,
As described below, the fixing by the prism mount 55 can be carried out in a state where the prism stand 41 hardly moves.

As shown in FIG. 5a, the set screw 55 loosely passes through the through hole 53 on the main body side, and a part (most part) of the threaded part is shown in FIG. ) is the screw hole 4 of the prism stand 41.
7, and the countersunk portion of the set screw 55 is in a floating state without contacting the bottom surface 57A of the recess 57. In other words, since the set screw 55 is engaged only with the prism stand 41, even if the set screw 55 is rotated from this state, the prism stand 41 will hardly move from the main body 2 side. However, the fifth
When the set screw 55 is rotated from the state shown in FIG. 5A, the state shown in FIG. When the set screw 55 is further rotated in this state, the countersunk portion of the set screw 55 is moved into the recess 5.
7, the prism stand 41 side is drawn toward the main body 2 side, and the prism stand 41 is firmly fixed. (In this case, prism stand 4
1 and the upper surface of the main body 2 side, even if the set screw 55 is rotated, the prism base 41
(This can prevent the eccentric pin 5 from moving (shifting).) When fixing, the eccentric pin 5 is
1 is engaged in the elongated hole 45 of the prism stand 41, it is possible to prevent the prism stand 41 from moving during fixation.

As mentioned above, in one embodiment, set screws 54,5
5 is used to fix the prism stand 41 in such a way as to pull the prism stand 41 when fixing, and each of the setscrews 54 and 55 is designed so that there is no friction on the surface on the main body side to which the prism stand 41 is fixed. The prism 41 is not moved until it is activated. After fixing the prism stand 41, the driver 48 can be pulled out to complete the installation of the critical angle prism 33.

In the first embodiment, the critical angle prism 33 is used as an optical member that requires fine adjustment and installation.
However, it is equally applicable to other optical members. That is, an optical member that requires (or is desired) to be finely adjusted is fixed to a stand, a long hole 45 etc. is provided in the stand, and a hole 45 etc. is provided on the main body side to which the stand is fixed for fine adjustment of the angle or position. Fitting hole 49 for adjustment driver 48 communicating with elongated hole 45
The eccentric pin 51 protruding from the tip side of the driver lever 48 can be inserted into the long hole 45 to enable fine adjustment, and the through hole 52 on the main body side,
Screws 54, 55, etc. having loose threads 53, etc. may be screwed into screw holes provided in the base to form a means for fixing the base by drawing it toward the main body.

The present invention is not limited to magneto-optical optical pickup devices, but can be widely applied to optical recording and reproducing devices that perform at least one of recording and reproducing using a light beam.

[Effects of the invention] As described above, according to the invention, it is possible to finely adjust an optical member that requires fine adjustment using a driver in which an eccentric pin is inserted into a long hole, and it is also possible to finely adjust an optical member that requires fine adjustment. At the same time, a fixing means is formed to pull and fix the table to which the optical member method is fixed.
The optical member can be fixed with almost no displacement during fixation. Therefore, the original functions of each optical member can be fully exhibited, and a highly accurate optical pickup device can be realized. Further, the structure of the fixing means is simple, the number of parts to be attached is small, and it can be realized at low cost.

[Brief explanation of the drawing]

Figures 1 to 5 relate to one embodiment of the present invention, Figure 1a is a plan view showing a prism stand on which a critical angle prism is fixed in one embodiment, and Figure 1b
is an enlarged cross-sectional view taken along the line B-B' in the state in which the prism mount shown in FIG. Figure 2b is a side view of the lens actuator, Figure 3 is a plane view of the main body to which the prism mount is attached, Figure 4a is the fine adjustment driver. front view, 4th
Fig. b is a side view of Fig. a, and Fig. 5 is a sectional view showing a state in which the prism stand is being installed. DESCRIPTION OF SYMBOLS 1... Optical pick-up device, 2... (Pick-up) main body, 3... Laser diode, 6... Collimator lens, 12... Total reflection mirror, 33...
...Critical angle prism, 41... Prism stand, 42,
57... recess, 43, 52, 53... through hole, 44
... Pin, 45 ... Long hole, 46, 47 ... Screw hole, 48 ... Driver, 49 ... Fitting hole, 54,
55... Set screw.

Claims (1)

[Claims for Utility Model Registration] Used for recording information on the recording medium or reproducing the recorded information by irradiating an optical recording medium with a focused light beam in the form of a spot. In an optical pickup device, an optical member whose mounting position or angle needs to be finely adjusted; an optical member fixing table which is rotatable and fixes the optical member close to the center of rotation; A hole is provided in the optical member fixing base, extending in a direction substantially orthogonal to the rotational direction of the optical member fixing base, at a position further away from the optical member with respect to the rotation center of the member fixing base. an elongated hole; a main body for fixing the optical member fixing base; a fitting hole provided in the main body into which an adjustment member protrudingly provided with an eccentric pin that is engaged in the elongated hole is fitted; The optical member fixing table is rotated by rotating the elongated hole by rotation of the eccentric pin, and fine adjustment of the mounting position or angle of the optical member is performed. 1. An optical pickup device comprising means for fixing a set screw loosely passing through a through hole formed in the optical member fixing base by screwing it into a screw hole formed in the optical member fixing base.