JPH0333934Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a pickup device in an optical information reading device.

BACKGROUND ART In an optical information reading device, an information recording medium such as a video disk or a digital audio disk has minute pits (dents) formed in the form of spiral tracks on its surface in accordance with information signals. Therefore, the information signal is recorded. When reading an information signal recorded in this way, a spot light is irradiated onto the track while rotating the disk at a predetermined number of revolutions, and changes in the intensity of the reflected light are converted into an electrical signal, and the original information signal is read. It is to be reproduced as a.

Various pick-up devices for information reading devices have been proposed in the past, one example of which is shown in FIG.

In FIG. 1, a holding member 1 has a through hole 2 and a hole 3 parallel to the through hole. Through hole 2
A counterbore portion 4 is formed at the open end of the counterbore, into which a laser diode 5 as a light emitting element is fitted, and one end of which is attached to a presser spring 7 fixed to the holding member 1 with a screw 6. Therefore, it is pressed and fixed to the holding member 1. Further, a collimator lens 9 is disposed approximately in the middle of the through hole 2 in the axial direction. On the other hand, a plate 10 is provided at the open end of the hole 3 and is fixed to the holding member 1 with screws 11. A counterbore portion 12 is formed in the plate 10, and a light receiving element 13 is fitted into the counterbore portion. Further, the inner end of the hole 3 is enlarged in diameter, and each holder 1 is provided in the enlarged diameter portion 15.
A pair of cylinder lenses 17 supported by cylinder lenses 6 are provided. The enlarged diameter portion 15 and the through hole 2 are the communication hole 1
9. This communication hole 1
A beam splitter 20 is provided within the beam splitter 9. An actuator 21 is disposed at the other open end of the through hole 2 and is fixed to the holding member 1 with a screw 22 . A through hole 23 coaxial with the through hole 2 is formed in the actuator 21 . The diameter of the through hole 23 is enlarged on the side not facing the through hole 2, and an objective lens 25 is disposed within the enlarged diameter portion 24. The objective lens 25 is supported by a support mechanism (not shown) so as to be movable in the optical axis direction (focusing direction) of the irradiation light beam L _a emitted from the laser diode 5 and in the direction perpendicular thereto (tracking direction). In addition, the objective lens 25
is a coil (not shown) and a magnetic circuit (not shown)
It is designed to be driven in two directions, the focusing direction and the tracking direction, by an electromagnetic driving means consisting of the like.

Next, the process of assembling the above-mentioned pickup device will be briefly explained.

First, the collimator lens 9 is inserted into the through hole 2 and temporarily fixed at an appropriate position, and then the laser diode 5 is fitted into the counterbore portion 4 and fixed with the presser spring 7. Next, the cylinder lens 17, which has been attached to the holder 16 in advance, is inserted into the enlarged diameter portion 15 and temporarily fixed at a predetermined position. After that, the reflected light beam from the disk (not shown) enters the objective lens 25, the beam splitter 20, and the cylinder lens 17.
Adjustment is made so that the optical axis of L _b exactly coincides with the center of the light receiving surface of the light receiving element 13 . To explain this adjustment in detail, first, warm up the screw 11 slightly and tighten the plate 1.
0. Therefore, the light-receiving element 13 is appropriately shifted in a direction perpendicular to the optical axis, the optical axis and the center of the light-receiving surface of the light-receiving element 13 are approximately aligned, and the screw 11 is tightened. Next, the temporarily fixed holder 16 and therefore the cylinder lens 1
7 is finely adjusted in a direction perpendicular to the optical axis, so that the optical axis and the center of the light-receiving surface of the light-receiving element 13 are perfectly aligned. It is confirmed that the optical axis of the reflected light beam coincides with the center of the light-receiving surface by measuring the change in the output signal with a predetermined measuring instrument. After this adjustment is completed, the position of the collimator lens 9 is adjusted in the optical axis direction of the irradiation light beam L _a so that the zero point of the focus error signal and the in-focus point coincide.

As mentioned above, in the pickup device of the information reading device that has already been developed, in order to align the optical axis of the reflected light beam L _b with the center of the light-receiving surface of the light-receiving element 13, the position of the light-receiving element 13 is adjusted and the cylinder lens 17 is adjusted. This requires two complicated operations, ie, fine adjustment of the position, which is time consuming and increases the cost. Incidentally, if the position adjustment of the light-receiving element 13 is omitted from among these two adjustment operations, the adjustment stroke of the cylinder lens 17 must be increased by that amount, and therefore the axial center of the cylinder lens 17 and the optical axis are largely deviated. This results in aberrations that adversely affect the error signal. Also,
In addition to the problem of having to perform the adjustment work twice, there is also a drawback that the output cable of the light-receiving element 13 is easily broken when adjusting the position of the light-receiving element 13.

Summary of the invention (purpose of the invention) The invention has been made in view of the above-mentioned points, and its purpose is to simplify the adjustment work to align the optical axis of the reflected light beam with the center of the light-receiving surface of the light-receiving element. Therefore, it is an object of the present invention to provide a pickup device which is low in cost, has no possibility of disconnection of the output cable of a light receiving element during adjustment, is small and lightweight, and is easy to assemble.

(Structure of the invention) A pickup device according to the invention includes a light-emitting element, a light-receiving element, and a holding member that holds the light-emitting element and the light-receiving element, and the light-emitting element and the light-receiving element are attached to the holding member. It is characterized in that it is attached by a fixing member, and at least one of the light emitting element and the light receiving element is held between the holding member and the fixing member.

Embodiment Hereinafter, a pickup device in an optical information reading device as an embodiment of the present invention will be described with reference to FIGS. 2a and 2b. The pickup device shown in FIGS. 2a and 2b has the same structure as the conventional pickup device shown in FIG. 1 except for the parts explained below, and in the following explanation, the pickup device shown in FIG. The same reference numerals are used for the same or corresponding parts.

As shown in the figure, the laser diode 5 and the light receiving element 13 are attached to the holding member 1 by a single fixing member 40. The fixing member 40 is fixed to the holding member 1 with screws 39. A through hole 42 is formed in the fixing member 40 coaxially with the hole 3 of the holding member 1, and the light receiving element 13 is inserted into the through hole 42.
It is fitted into a counterbore portion 43 provided at the open end of. On the other hand, the laser diode 5 has a counterbore portion 4 formed at the open end of the through hole 2 of the holding member 1.
is fitted into the fixing member 4 via the plate spring 44.
Attached by 0. That is, the laser diode 5 is held between the holding member 1 and the fixing member 40. As is clear from FIG. 2b, the fixing member 40 has a long hole 46 and a round hole 47 that respectively engage with a pair of pins 45 protruding from the contact surface of the holding member 1 with the fixing member. It is formed.
The relative positional accuracy between the counterbore portion 4 into which the laser diode 5 is fitted and these pins 45 is high, and the relative positional accuracy between the counterbore portion 43 into which the light receiving element 13 is fitted and the elongated hole 46 and the round hole 47 is high. The dimensional accuracy of relative positions has also become extremely high. Therefore, the dimensional accuracy of the relative positions of the laser diode 5 and the light receiving element 13 is improved.

As described above, the laser diode 5 and the light receiving element 13 are connected to the holding member 1 by the common fixing member 40.
By attaching the laser diode 5 to the light receiving element 13, the dimensional accuracy of the relative position of the laser diode 5 and the light receiving element 13 is extremely improved. On the other hand, regarding the beam splitter 20, the two surfaces of the beam splitter, namely the semi-transparent surface 20a and the reflective surface 20b, are opposing surfaces within the same block, so the parallelism and spacing between these two surfaces are highly accurate. You can. Therefore, even if there is some error in the mounting position of the beam splitter 20 in the communication hole 19, the optical axis of the irradiated light beam L _a and the reflected light beam L _b can be adjusted due to the two-mirror prototype.
The parallelism between the beam splitter and the optical axis is ensured, and the error in the separation distance between the two optical axes is sufficiently small compared to when the beam splitter is in the normal position. Therefore, the optical axis of the reflected light beam L _b almost coincides with the center of the light receiving surface of the light receiving element 13, and the reflected light beam L _b
The adjustment work to accurately align the optical axis of the cylinder lens 1 with the center of the light receiving surface of the light receiving element 13 is to
Only the simple position adjustment described in step 7 is required.

In the above-mentioned pickup device, the laser diode 5 is fitted into the counterbore portion 4 formed on the holding member 1, and the light receiving element 13 is disposed within the counterbore portion 43 provided on the fixing member 40. However, on the contrary, there is a method in which the holding member 1 is provided with a counterbore, the light receiving element 13 is disposed within the counterbore, and the laser diode 5 is fitted into the counterbore formed in the fixing member 40. It is also possible to do this. Further, a pair of counterbore portions are formed on the surface of the fixing member 40 facing the holding member 1, and a laser diode 5 and a light receiving element 13 are respectively disposed in the counterbore portions. It is also possible to use a type in which the holding member 1 and the fixing member 40 are held between each other, for example, via a disc spring.

As described above, since at least one of the laser diode 5 as a light emitting element and the light receiving element 13 is supported by the holding member 1 and the fixing member 40, the laser diode 5 or the light receiving element 13 is supported by the fixing member 40. There is no need for fixing means such as wax or adhesive for attachment, and the assembly of the pick-up device is simplified and the pickup device is made smaller and lighter.

Effects of the Invention As detailed above, in the pickup device of the optical information reading device according to the present invention, the light emitting element and the light receiving element are attached to the holding member that holds the light emitting element and the light receiving element by a single fixing member. Therefore, the dimensional accuracy of the relative position between the light emitting element and the light receiving element is extremely improved. Therefore, for example, by utilizing the action of the two-mirror principle of the beam splitter provided in the holding member, the optical axis of the reflected light beam from the disk and the center of the light-receiving surface of the light-receiving element can be approximately aligned. I can force it. Therefore, the only adjustment work required to accurately match the optical axis of the reflected light beam with the center of the light receiving surface of the light receiving element is, for example, fine adjustment of the cylinder lens, which greatly simplifies the adjustment work and reduces costs. It is becoming easier to achieve this.

Further, as mentioned above, in the pick-up device in the optical information reading device according to the present invention,
Since the position of the light-receiving element is not adjusted, there is no possibility of disconnection of the output cable of the light-receiving element due to the position adjustment of the light-receiving element, as in already developed pickup devices.

Further, in the pickup device according to the present invention, at least one of the light emitting element and the light receiving element is held between the holding member and the fixing member. Because of this configuration, there is no need for fixing means such as wax or adhesive to attach the light-emitting element or light-receiving element to the fixing member, and the assembly of the pick-up device is simplified and the pick-up device is made smaller and lighter.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a previously developed pickup device, and FIG. 2 is a sectional view of a pickup device as an embodiment of the present invention. Explanation of symbols of main parts, 1... Holding member, 5...
... Laser diode, 7 ... Presser spring, 9 ... Collimator lens, 10 ... Plate, 13 ... Light receiving element, 20 ... Beam splitter, 25 ... Objective lens, 40 ... Fixing member, 44 ... Dish Spring.

Claims (1)

[Scope of utility model registration request] It includes a light emitting element, a light receiving element, and a holding member that holds the light emitting element and the light receiving element, the light emitting element and the light receiving element are attached to the holding member by a single fixing member, and the light emitting element and the light receiving element are attached to the holding member by a single fixing member. 1. A pick-up device for an optical information reading device, wherein at least one of the pick-up devices is held between the holding member and the fixing member.