JPH07272306A - Fixing structure for photodetector - Google Patents

Abstract

PURPOSE:To surely fix a photodetector with once soldering by laminating a flexible printed circuit board(FPC) having through holes through which pins of the photodetector pass and the FPC having the through holes with through hole sizes larger than the through holes and using them. CONSTITUTION:The FPC 2 of a movable plate having the small-sized through holes 5 through which the pins 7 of the photodetector 8 pass is superposed on the FPC 1 having the through holes 6 with through hole sizes larger than the through holes 5, and the soldering is performed by using them. Then, solder 3 flow in excellently through the through holes 6, and the photodetector is fixed surely by a once soldering process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing structure for adjusting and fixing a photodetector such as a photoelectric conversion element having a pin to an object to be adjusted in an optical disk device.

[0002]

2. Description of the Related Art An optical disk device collects a light beam from a semiconductor laser by an objective lens to the diffraction limit of light and forms a minute spot of about 1 μm on an optical information recording medium. The reflected light from the spot formed on the optical information recording medium is guided to a detection optical system and photoelectrically converted by a photodetector to detect information.

As a prior art of such a fixed structure of the photodetector, for example, there is one disclosed in Japanese Utility Model Laid-Open No. 3-14723. That is, a photodetector having a plurality of lead wires, which receives reflected light from an optical disc, converts the light into an electric signal, and outputs the electric signal from each of the lead wires; and an FPC electrically connected to each of the lead wires, In an optical head device including an FPC attached, an optical axis direction of the reflected light and a movable plate that is positionally adjusted in a direction perpendicular to the optical axis direction and is adhesively attached to an optical head device body, the photodetector is the The optical head device is characterized in that it is adhered and fixed to the surface of the movable plate facing the main body of the optical head device so as to be positioned in the gap between the movable plate and the main body of the optical head device.

Specifically, as shown in FIG. 5, the photodetector 8 is fixed to the movable plate 17 with an adhesive 15.
Further, the movable plate 17 and the FPC 16 are fixed using an adhesive 14, and the pin 7 of the photodetector is soldered to the land portion 13 of the FPC 16 through the movable plate 17 and the FPC 16.

[0005]

In the above conventional technique, three types of fixing methods, that is, an adhesive, an adhesive, and soldering, are required to fix the photodetector, which increases the number of steps and the cost. There is a problem. Also, fixing with an adhesive is weak against changes over time, and peeling occurs between the FPC and the movable plate, stress is applied to the pins of the photodetector, and in the worst case, misalignment of the photodetector occurs. There is a point.
In particular, the position adjustment of the photodetector is performed in units of μm, and even if a position deviation of several μm occurs, it will have a great influence on focusing control and the like.

The present invention has been made to solve the above problems, and provides a fixing structure for a photodetector, which fixes the photodetector, the movable plate, and the FPC in one step, and is resistant to aging. The purpose is to

[0007]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and is a photodetector that receives light and converts it into an electric signal, and is electrically connected to the photodetector. In a fixed structure of an FPC (flexible printed wiring board) and a movable plate to which the photodetector and the FPC are attached, a through hole through which a pin of the photodetector provided in the FPC passes. Section, a land section provided around the through hole section, a pin of the photodetector provided on the movable plate, and the FPC.
Is a through-hole portion smaller than the through-hole portion and a connecting portion for connecting and fixing these through-hole portions. Further, a semicircular through hole portion through which the pin of the photodetector provided on the FPC passes, a land portion provided around the through hole portion, and a pin of the photodetector provided on the movable plate. The photodetector fixing structure is characterized by having a through-hole portion through which a through hole and a connecting portion connecting and fixing these through holes. The width of the FPC is up to the end of a semi-circular land, and the FP
The distance between the through holes of C is shorter than the distance between the through holes of the movable plate.

[0008]

In the fixed structure of the photodetector according to the present invention,
The FPC and movable plate have through holes,
Since the through hole part of the movable plate is larger than the through hole part of the movable plate, when solder is poured from the through hole part of the FPC after inserting the pins of the photodetector into these through hole parts, The solder flows into the entire through hole portion of the movable plate having a smaller diameter than the through hole portion of the FPC, and the pin of the photodetector is securely fixed to the FPC and the movable plate in one step. It Further, by making the through hole portion of the FPC semicircular, the distance of the land can be made larger, short circuit can be prevented, and further, by making the width of the FPC to the end of the semicircular land portion, FPC becomes smaller,
The fixing strength by soldering can be increased and the workability of soldering is improved. Since the distance between the through holes of the FPC is slightly shorter than the distance between the through holes of the movable plate, it is possible to prevent the FPC from partially blocking the through holes of the movable plate. At this time, the solder flows into the entire through hole of the movable plate, and the pin of the photodetector is F
Securely fixed to the PC and movable plate in one step.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the accompanying drawings. FIG. 6 shows an outline of an optical pickup in an optical disk device. In the figure, reference numeral 20 denotes a semiconductor laser, and a light flux from this semiconductor laser 20 is collimated by a collimator lens 21 to be parallel light, transmitted through a beam splitter 22, and passed to an objective lens 23. Incident. Then, the objective lens 23 irradiates the information recording medium 24 as a minute spot. The reflected light from the information recording medium 24 becomes parallel light again by the objective lens 23, and the beam splitter 2
The light is reflected downward in the figure at 2 and guided to the detection lens 25. The light flux is again condensed by the detection lens 25, part of which is transmitted by the knife edge prism 26, is guided to the focusing error signal photodetector 27, and the rest is guided to the polarization beam splitter 28. Polarizing beam splitter 2
The light guided to 8 is split into P wave and S wave, and is guided to the photodetector 29 for detecting the tracking error signal and the other to the photodetector 30 for detecting the reproduction signal. Here, the focusing error signal is detected by the known knife edge method, and the tracking error signal is detected by the known push-pull method. Further, the reproduced signal includes a tracking error signal detection photodetector 29 and a reproduction signal detection photodetector 30.
Detected by the difference in the output from the.

Here, the focusing error signal detecting photodetector 27 and the tracking error signal detecting photodetector 29 are in the direction of the arrow (in the case of the tracking error signal detecting photodetector 29, the direction perpendicular to the paper surface). It is adjusted to the μm unit. In particular, the positional accuracy of the focusing error signal detecting photodetector 27 is severe, and a 1 μm positional deviation causes a focus deviation of about 0.2 μm. Therefore, even if the positional deviation of the photodetector is several μm, it has a great influence, and in the worst case, recording and reproduction cannot be performed.

The present invention provides a fixing structure for a photodetector that is resistant to aging and has no positional deviation.
The embodiment will be described with reference to FIG.

(A) is a plan view (solder not shown),
(B) is a cross-sectional explanatory view, in which 1 is an FPC (flexible printed wiring board), and this FPC 1 is provided with a through hole portion 6 having a land portion. This FPC1
A movable plate 2 having a through hole portion 5 wider than the FPC 1 and having a land portion is disposed on the lower surface (in the figure) of the. The diameter of the through hole portion 6 of the FPC 1 is larger than the diameter of the through hole portion 5 of the movable plate 2.

Two pins 7 of the photodetector 8 are inserted into the through holes 6 and 5 of the FPC 1 and the movable plate 2 from the side of the movable plate 2 and arranged on the movable plate 2. And FP
Pour the solder from the side of the through hole 6 of C1,
The PC 1, the movable plate 2, and the pin 7 of the photodetector 8 are fixed by soldering. At this time, the solder 3 penetrates deep into the through hole portion 5 of the movable plate 2, and the FPC 1, the movable plate 2, and the photodetector 8 can be fixed by soldering once. In addition, 4 in the figure
Is a signal line connected to the land portion and supplying power, signals, and the like.

Next, a second embodiment of the present invention will be described with reference to FIG. This embodiment is similar to the first embodiment in the FPC10.
Is provided with a through hole portion 9 having a land portion. On the lower surface (in the figure) of the FPC 10,
A movable plate 2 having a wider through hole portion 5 having a land portion is arranged.

By the way, in the case of the first embodiment, the land diameter of the FPC becomes large, and there is a possibility of short-circuiting if the pin pitch of the photodetector is short. In order to avoid this, in the second embodiment, the FPC 10 is provided with the through hole portion 9 having a semicircular land having a diameter substantially the same as the land diameter of the through hole portion 5 provided on the movable plate 2. ing. As a result, the land interval can be made large, and the photodetector 8 will not be short-circuited. Further, as in the first embodiment, the solder 3 penetrates deep into the through hole portion 5 of the movable plate 2 and is soldered once. Thus, the pin 7 of the photodetector 8 can be fixed to the movable plate 2 and the FPC 10.

A third embodiment will be described with reference to FIG.
In this embodiment as well, as in the first embodiment, the FPC 11 is provided with a through hole 9 having a land. This FP
A movable plate 2 having a through hole portion 5 wider than the FPC 11 and having a land portion is arranged on the lower surface (in the figure) of C11.

Here, in this embodiment, the FPC is used.
The width is shortened by combining 11 with a semicircular land. As a result, the size of the FPC is reduced, the fixing strength by soldering can be increased, and the workability of soldering is improved.

A fourth embodiment will be described with reference to FIG.
In this embodiment as well, as in the first embodiment, the FPC 12 is provided with a through hole portion 9 having a land portion. This FP
A movable plate 2 having a through hole portion 5 wider than the FPC 12 and having a land portion on the lower surface (in the figure) of the C12.
Are arranged.

When the center of the through hole portion 5 of the movable plate 2 and the center of the through hole portion 9 of the FPC 12 are the same, the through hole portion 5 of the movable plate 2 is partially blocked by the FPC 12 depending on the variation in work. As a result, a phenomenon occurs in which the solder 3 does not sufficiently go around the through hole portion 5. Therefore, in this embodiment, the distance between the through holes 9 of the FPC 12 is slightly shorter than the distance between the through holes 5 of the movable plate 2. By doing so, it is possible to prevent the through hole portion 5 of the movable plate 2 from being partially blocked by the FPC 12, and the photodetector 8 can be fixed to the movable plate 2 and the FPC 12 by one soldering operation. . In addition, the area where the land portion of the FPC 12 and the land portion of the movable plate 2 are in contact with each other becomes large, and the fixing strength by soldering can be further increased. In the present invention,
Since it is fixed by the solder 3, peeling due to aging does not occur.

[0020]

As described above, according to the present invention,
The FPC and movable plate have through holes,
Since the through hole portion of the movable plate is larger than the through hole portion of the movable plate, the solder flows into the whole and the soldering process is performed in a single soldering step without using an adhesive or an adhesive.
The PC, the photodetector, and the movable plate can be fixed, and the influence due to aging can be prevented. Moreover, since the FPC and the movable plate have through holes, and the through holes of the FPC have a semicircular shape, there is no risk of short-circuiting, and the solder will flow into the entire area without using adhesive or adhesive. The FPC, the photodetector, and the movable plate can be fixed in one soldering step. Further, the FPC and the movable plate have through holes, and the through holes of the FPC have a semicircular shape. Since the width of the FPC is up to the end of the semicircular land, the solder flows into the whole and is bonded. FPC, photodetector, in one soldering process without using adhesive or adhesive
The movable plate can be fixed more strongly, and the FPC can be reduced. The FPC and the movable plate have through holes, the through holes of the FPC have a semicircular shape, and the distance between the through holes of the FPC is slightly shorter than the distance between the through holes of the movable plate.
The through-hole of the movable plate is not partially blocked by this, and the solder flows into the entire area, and the FPC, the photodetector, and the movable plate can be removed in a single soldering process without using an adhesive or an adhesive. Can be firmly fixed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a first embodiment.

FIG. 2 is an explanatory diagram showing a second embodiment.

FIG. 3 is an explanatory diagram showing a third embodiment.

FIG. 4 is an explanatory diagram showing a fourth embodiment.

FIG. 5 is an explanatory diagram showing a conventional technique.

FIG. 6 is a schematic explanatory diagram of an optical disc device.

[Explanation of symbols]

 1 FPC 2 movable plate 3 solder 4 signal line 5 through hole part 6 through hole part 7 pin 8 photodetector 9 through hole part 10 FPC 11 FPC 12 FPC 20 semiconductor laser 21 collimator lens 22 beam splitter 23 objective lens 24 information recording medium 24 25 Detection Lens 26 Knife Edge Prism 27 Photo Detector 28 Polarizing Beam Splitter 29 Photo Detector 30 Photo Detector

Claims (4)

[Claims] 1. A photodetector for receiving light and converting it into an electric signal, an FPC (flexible printed wiring board) electrically connected to the photodetector, and a movement to which the photodetector and the FPC are attached. In a fixed structure of a photodetector including a movable plate, a through hole portion through which a pin of the photodetector provided in the FPC is passed, a land portion provided around the through hole portion, and the movable plate. 2. A fixing structure for a photodetector, comprising: a through hole through which a pin of the photodetector is provided and which is smaller than a through hole part of the FPC; and a connecting portion for connecting and fixing these. 2. A photodetector that receives light and converts it into an electric signal, an FPC (flexible printed wiring board) electrically connected to the photodetector, and a movement to which the photodetector and the FPC are attached. In a fixed structure of a photodetector composed of a movable plate, a semicircular through hole portion through which a pin of the photodetector provided in the FPC passes, and a land portion provided around the through hole portion, 2. A fixing structure for a photodetector, comprising: a through hole provided on the movable plate, through which a pin of the photodetector passes, and a connecting part for connecting and fixing these. 3. The fixing structure for a photodetector according to claim 2, wherein the width of the FPC is up to the end of a semi-circular land portion. 4. The fixing structure for a photodetector, wherein the distance between the through holes of the FPC is shorter than the distance between the through holes of the movable plate.