JPH0439742B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention provides at least one function of reading information recorded on a data track on a recording medium or optically recording information on a recording medium. The present invention relates to an optical head of an optical information recording/reproducing apparatus having an optical head, and particularly to an adjustment structure suitable for optimally adjusting the positional relationship between a light spot and a data track on a recording medium.

[Prior Art] Conventionally, this type of optical head is known as one used in, for example, an optical video disc player, a compact disc player, etc., and their diffraction grating adjustment mechanisms are shown in FIG. What is shown is common.

In the figure, 1 is a semiconductor laser, 2 is a diffraction grating, 3 is a half prism, 4 is an objective lens, 5 is a sensor lens, 6 is a photodetector, 30 is a grating holder, 31 is an eccentric driver, and 32 is a disk.

Next, the operation will be explained. In FIG. 9, the laser beam emitted from the semiconductor laser 1 is split into a plurality of diffracted beams after entering the diffraction grating 2, of which at least the 0th-order beam and the ±-order beam pass through the half prism 3 and are reflected into the objective. The light that is focused on the disk 32 by the lens 4 and reflected by the disk 32 passes through the objective lens 4 in the opposite direction to the incident light, and is reflected by the half prism 3 in the right angle direction. The reflected light passes through a sensor lens 5 and is received by a photodetector 6.

As shown in Figure 10, the three beams of the 0th order light and ±1st order light of the divided laser light are
2, the reflected light is focused at an angle to the pit row, and the 0th-order beam enters B1 to B4 of the photodetector light receiving element in Fig. 10, and the ±1st-order beam enters A1 in the same figure. , A2. The 0th order beam is
The ±1st order beam is used to detect the information signal on the disk and the focus error signal, and the difference signal (A1-A2) between the light receiving sections A1 and A2 becomes the tracking error signal.
Track control is performed by adjusting the optical system in advance so that this becomes zero. By adjusting the angle of the ±1st-order beams on the disk 32 with respect to the pit row to the optimum angle, track control can be improved. For this reason, as shown in FIG. 9, the diffraction grating 2 is fixed to a grating holder 30 with grooves, and the angle between the ±1st order beam and the pit row is finely adjusted using an eccentric driver 31 to achieve good track control. do.

[Problems to be Solved by the Invention] In the conventional diffraction grating adjustment mechanism, the groove into which the eccentric driver 31 is inserted is formed on the cylindrical surface of the grating holder 30 parallel to the optical axis. Insert direction of disc 3 into the grid holder.
The only direction possible was parallel to the plane of 2. For this reason,
There have been problems in that it is difficult or impossible to adjust the diffraction grating 2 after the optical head has been incorporated into an optical information recording/reproducing device.

The present invention has been made to solve the above-mentioned problems, and in order to facilitate the angle adjustment of the diffraction grating of an optical head incorporated in an optical information recording/reproducing device, The purpose is to obtain a mechanism that can be adjusted from the vertical direction.

[Means for Solving the Problems] The diffraction grating adjustment mechanism according to the present invention has a protrusion (arm) of an appropriate shape protruding from the cylindrical surface of a diffraction grating holder that stores and holds a diffraction grating, and a diffraction grating is attached to the protrusion. Grooves are provided in the radial direction centered on the optical axis that runs through the grating, and eccentric pins are inserted in the direction perpendicular to the grooves. A desired eccentric pin receiving hole is provided in the groove of the diffraction grating holder into which the eccentric pin is incorporated, and the first shaft portion provided at one end of the eccentric pin is inserted into this receiving hole, and the optical head is inserted into the groove. is rotatably inserted into the head base of the head. A second shaft part concentric with the first shaft part is also provided at the other end of the eccentric pin, and is supported by a cover attached from the lower part of the head base. Further, the end of the second shaft portion is provided with a desired groove, such as a single-letter groove, so that it can be turned with a flathead screwdriver or a Phillips screwdriver.

[Function] The diffraction grating adjustment mechanism of the optical head according to the present invention makes it possible to easily adjust the diffraction grating from below the device using a driver or the like even after the optical head is incorporated into an optical information recording/reproducing device. .

[Example] The following is a first example of an optical head according to the present invention.
This will be explained using FIGS. 8 to 8. In the description, the same or equivalent parts as in the conventional example are given the same reference numerals, and some descriptions will be omitted. In FIG. 1, 1 is a semiconductor laser that emits laser light, 2 is a diffraction grating that separates the laser light into multiple parts, 3 is a half prism, 4 is an objective lens that focuses the laser light emitted from the semiconductor laser, and 5 is a diffraction grating that separates the laser light into multiple parts. A sensor lens that has both the functions of a concave lens and a cylinder lens, 6 is a photodetector, 7 is a diffraction grating holder that holds the diffraction grating 2 rotatably in the direction of arrow A around the optical axis, and 8 is a diffraction grating holder. 7 is an eccentric pin for rotating, 9 is a sensor lens holder that holds the sensor lens 5 slidably in the optical axis direction, and 100 is an objective lens that displaces the objective lens 4 in the optical axis direction B and the track adjustment direction C. Movement mechanism (hereinafter abbreviated as actuator)
It is.

In such a configuration, laser light (not shown) emitted from the semiconductor laser 1 is diffracted by the diffraction grating 2 into a plurality of light beams. Of the diffracted lights, at least the 0th-order light and the ±1st-order light pass through the half prism 3 and enter the objective lens 4, forming a light spot on a disk (not shown). The light reflected by the disk passes through the objective lens 4 in the opposite direction to the incident light, and is reflected by the half prism 3 in the right angle direction. The reflected light passes through the sensor lens 5, causes astigmatism, and is received by the photodetector 6. Here, the photodetector 6 detects the information on the disk, and at the same time detects the distance between the disk and the objective lens 4 and the amount of deviation between a track (not shown) on the disk and the light spot, and detects each Depending on the detected amount, the objective lens 4 is moved by an actuator 100 in the optical axis direction of arrow B and in the direction of arrow C, which is substantially perpendicular to the track.

Specific configuration examples for realizing the above-described apparatus are shown in FIGS. 2 to 4.

In each figure, 10 is a head base, and 11 is a part for fixing the semiconductor laser 1 to the head base.
LD holding plate, 12a, 12b are LD fixing screws, 13
14a and 14b are grating springs for pressing the diffraction grating holder 7 against the head base 10, and 14a and 14b are interposed between the diffraction grating holder 7 and the grating spring 13, so that the holder 7 can smoothly rotate in the direction of arrow A. 15 is a detector substrate holding the photodetector 6; 16 is the photodetector 6;
Detector covers 17a and 17b protect the detector board 15, and the detector cover 6 protects the head base 10.
18 is an actuator cover that protects the actuator 100, 101 is an actuator holder to which the objective lens 4 is attached eccentrically, and 102 is wrapped around the lower part of the actuator holder. 103a and 103b are track control coils provided at both ends of the upper part of the actuator holder.
14 is a permanent magnet for focus control, 105 is an AF yoke that holds the permanent magnet for focus control, 106a, 10
6b is a permanent magnet for track control, 107a, 10
7b is a back yoke fixedly provided on the back side of the permanent magnet for track control; 108a and 108b are bases for holding the permanent magnet for track control; 109
a, 109b, 109c, 109d are the base 108
110 is a support rubber that elastically holds the actuator holder 101, which is a movable part, and the head base 10, which is a fixed part; 111a, 1
Reference numeral 11b indicates a support rubber fixing pin that is fixedly erected on the head base 10, 112 is a support pin that is press-fitted into the AF yoke 105 and press-fitted into the head base 10, and 113 is an actuator holder 101.
This is a stopper that reduces the collision of the AF yoke 105.

As shown in FIGS. 7 and 8, the diffraction grating holder 7 that holds the diffraction grating 2 is provided with an appropriately shaped protrusion (arm) 7a from the cylindrical surface of the diffraction grating holder 7. When viewed from a direction parallel to the optical axis passing through the diffraction grating 2, a groove 7b is provided in the radial direction centering on the optical axis, and an eccentric pin hole receiving hole 7c is provided approximately on the axis of the groove 7b in the radial direction. Further, as shown in FIGS. 5 and 6, the first shaft 8 is coaxial with the abdomen 8a at the center of the eccentric pin 8.
b and a second shaft portion 8c are provided at both ends of the eccentric pin 8, and between the abdomen 8a and the first shaft portion 8b,
It has an eccentric pin portion 8d having an axis located a predetermined distance apart from the axis of the abdomen 8a. The first shaft portion 8b of the eccentric pin 8 is inserted into the pin receiving hole 8c of the diffraction grating holder 7 so that the eccentric pin portion 8d and the groove 7b fit together. In addition, the pin receiving hole 7c
is a hole having a desired diameter larger than the diameter of the first shaft portion 8b. The end of the first shaft portion 8b inserted into the pin receiving hole 7c is rotatably inserted and supported in a base hole 10a provided at a predetermined position of the head base. The second shaft portion 8c of the eccentric pin 8 is rotatably inserted and supported by a fixing plate hole 11a provided in the LD holding plate 11. Note that the second support part 8
A linear driver groove 8c is provided at the end of c so that the eccentric pin 8 can be rotated with a flathead screwdriver or the like.

Next, the operation of the diffraction grating adjustment mechanism will be explained. 1 and 3, by rotating the eccentric pin 8 with a flathead screwdriver or the like, the diffraction grating holder 7 is rotated in the direction of arrow A, and the inclination of the diffraction grating 2 can be adjusted. Also, eccentric pin 8
Since the second shaft portion 8c is fitted into the fixing plate hole 11a provided in the LD holding plate 11, the structure is such that the angle is unlikely to change due to vibration or the like after adjustment.

[Effects of the Invention] As described above, according to the present invention, a protrusion (arm) is provided on a cylindrical holder that fixedly holds a diffraction grating, and a groove is formed in a direction perpendicular to the optical axis of the diffraction grating.
An eccentric pin receiving hole is provided almost on the axis of the shaft, and an eccentric pin for adjusting the rotation angle is inserted into the hole, which is incorporated into the optical head, so that both ends of the eccentric pin are rotatably fixed. Since the adjustment can be made from the direction of the optical head using a flathead screwdriver or the like, even if the optical head is incorporated into an optical information recording/reproducing device, the adjustment can be easily made from below the device.

[Brief explanation of drawings]

FIG. 1 is a simplified configuration diagram showing the principle of an optical head of an optical information recording/reproducing apparatus according to the present invention, FIG. 2 is a plan view showing a specific example of the configuration, and FIG. 3 is a sectional view taken along - in FIG. 2. , FIG. 4 is a sectional view taken along - in FIG. 2, FIG. 5 is a front view of the eccentric pin according to the present invention, FIG. 6 is a side view, and FIG. 7 is a front view of the diffraction grating holder according to the present invention. FIG. 8 shows a side view, FIG. 9 shows a simplified configuration diagram of a conventional optical head, and FIG. 10 shows a principle diagram of a three-beam track control system for the optical head. In the figure, 1 is a semiconductor laser, 2 is a diffraction grating, 3 is a half prism, 4 is an objective lens, 5 is a sensor lens, 6 is a photodetector, 7 is a diffraction grating holder, 7a is a protrusion, and 7c is an eccentric pin receiver. 8 is an eccentric pin, 10 is a head base, 11 is an LD holding plate, and 100 is an actuator.

Claims (1)

[Claims] 1. A diffraction grating that splits a light beam from a light source into a plurality of light beams, an objective lens that focuses the split specific light beam onto an optical recording medium, and a drive mechanism for this objective lens. In an optical head in which an actuator unit and a photodetector for receiving a reflected beam from an optical recording medium are incorporated into a base, a cylindrical holder that houses and holds the diffraction grating has a desired shape on the cylindrical surface of the cylindrical holder. A protruding portion is provided, a groove is formed in the protruding portion in a radial direction centered on the optical axis passing through the diffraction grating, and an eccentric pin receiving hole is provided approximately on the axis of the groove, and the eccentric pin receiving hole is provided approximately on the axis of the groove. a first shaft portion having a desired diameter smaller than the hole; and a second shaft portion having an axis at a position offset by a predetermined distance from the axis of the first shaft portion and having a diameter approximately equal to the width of the groove; An eccentric pin consisting of a third shaft part and a fourth shaft part having coaxial axes with the first shaft part is inserted into the base so that the second shaft part fits into the groove. An optical head characterized by: 2. The fourth shaft part has an axis coaxial with the axis of the first shaft part, and has a diameter smaller than the diameter of the third shaft part, and the end of the first shaft part is rotatably held by the base, and the end of the fourth shaft part is rotatably held by a support hole provided in a plate externally fixed to the base. An optical head according to claim 1. 3. The optical head according to claims 1 and 2, wherein the end of the fourth shaft portion is provided with a linear groove for rotating an eccentric pin.