JPH09282698A - Fixing device for optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device for an optical element capable of adjusting the supporting body of the optical element in the respective three-dimensional directions and mitigating the stress due to the difference in a linear expansion coefficient between an optical chassis and the supporting body of the optical element. SOLUTION: A pin 20 capable of elastically deforming in the radial direction is forced fitted in engaged holes 16b, 16. Eeven when the engaged hole 16b is expanded or shirked due to temp. change, the pin 20 is deformable in the radial direction following up this, pin 20 is regidly fixed and no disorder happens. A mounting hole 17b having larger diameter than the outer diameter of the pin 2, the pin is inserted through the mounting hole 17, after the positional adjustment of the adjusting substrate 17 is completed, the land part 17c and the pin are soldered in the soldering part, the deforming force due to temp. change is absorbed by the elastity of the pin 20 and the position of the optical element 15 is not disordered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device such as an optical head used for reproducing or recording signals from a compact disc (CD), a digital video disc (DVD), a magneto-optical disc, etc. Optical elements such as pin photodiodes and other light receiving elements
The present invention relates to a fixing device for an optical element that is fixed after adjusting its mounting position.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing the outline of the internal structure of an optical head mounted on a compact disc player or the like. Reference numeral 1 is a laser diode capable of irradiating a laser beam (laser light), 2 is a beam splitter, 3 is a reflecting mirror, 4 is an objective lens, and 5 is a light receiving element. The laser light emitted from the laser diode 1 is incident on the side surface 2a of the beam splitter 2 at a predetermined incident angle.
A part of the laser light is reflected by the side surface 2 a and the direction thereof is changed to the direction of the reflecting mirror 3. Above the reflector 3,
The objective lens 4 is provided. In order to guide the laser light to the objective lens 4, the reflecting mirror 3 is installed in the optical head with a tilt at a predetermined angle. A disc (not shown) such as a CD or a DVD is loaded above the objective lens 4. The objective lens 4 can focus and irradiate the focused laser light on the signal recording surface of the disk by a focus servo function (not shown).

The return light reflected from the signal recording surface of the disc follows the path opposite to the above, a part of the return light is transmitted through the beam splitter 2, and is guided to the light receiving element 5 provided behind it. The light receiving element 5 is, for example, a pin photodiode, and the light receiving element 5 reads a signal recorded on the disc and detects a focus error signal and a tracking error signal. In this type of optical head, a laser diode 1, which is a light emitting element, is generally positioned and fixed on an optical chassis (fixing portion), and a light receiving element 5 such as a pin photodiode has a maximum light receiving output after assembly is completed. And is fixed to the optical chassis. FIG. 5 is a perspective view showing an example of a conventional fixing structure for the light receiving element 5.

Reference numeral 6 indicates an optical chassis of the optical head. The optical chassis 6 is die-cast molded from, for example, an aluminum alloy. In the optical chassis 6, the components of the optical system such as the laser diode 1, the beam splitter 2, the reflecting mirror 3 and the objective lens 4 (not shown) are mounted. Further, the light receiving element 5 is mounted on the adjustment substrate 7 serving as a support and fixed by soldering, and a small area portion indicated by a dotted line in the drawing is the light receiving portion 5a. The return light transmitted through the beam splitter 2 shown in FIG. 4 passes through the through hole 6c from the direction of (a), reaches the light receiving element 5, and is detected by the light receiving section 5a.

The adjustment substrate 7 is a PCB substrate or the like, and a wiring pattern (not shown) made of a conductor film is formed on the surface thereof. The adjustment substrate 7 is formed with a cutout portion 7a, which is a partial cutout, and the light receiving element 5 is formed in the cutout portion 7a.
And terminals 5b protruding from the light receiving element 5 are soldered to the wiring pattern. Female screw holes 6b, 6b are formed on the mounting surface 6a of the optical chassis 6,
The adjustment board 7 is provided with mounting holes 7b, 7b of slightly larger diameter, which are opposed to the female screw holes 6b, 6b. Then, the screws 10, 10 are inserted into the mounting holes 7b, 7b and screwed into the female screw holes 6b, 6b, and the adjustment board 7 is fixed to the mounting surface 6a.

The adjusting board 7 is attached to the mounting surface 6a of the optical chassis 6.
When it is attached to, the adjustment substrate 7 is position-adjusted in the XY plane within the gap range of the difference in the radial dimension between the screw 10 and the attachment hole 7b, and the light reception detection output from the light receiving element 5 is observed. The optimum position of the adjustment board 7 is found, and the screw 10 is tightened at that position to fix the adjustment board 7.

[0007]

However, in the fixing device shown in FIG. 5, the position of the adjusting substrate 7 can be moved within the XY plane to adjust the optimum mounting position. The position of the adjustment board 7 cannot be adjusted in the Z direction, which is the direction. Therefore, the XYZ of the light receiving element 5 is
In order to enable adjustment in the three-dimensional directions, first, another substrate whose position can be adjusted in the Z direction with respect to the mounting surface 6a of the optical chassis 6 is provided, and the light receiving element 5 is attached to this other substrate.
It is necessary to fix the adjustment board 7 on which is mounted with the screw 10 so that the position can be adjusted in the XY plane. As a result, the number of parts constituting the mounting device of the light receiving element 5 increases, the cost increases, and not only the number of assembling steps increase, but also the number of constituent parts from the optical chassis 6 to the light receiving element 5 increases. Therefore, the number of elements that cause positional deviation between the light receiving unit 5a and the optical axis of the return light increases accordingly.

Further, in the structure in which the adjusting substrate 7 is fixed by the screw 10 as shown in FIG. 5, after the positioning of the light receiving element 5 is completed, the slack of the screw 10 causes the positional displacement of the adjusting substrate 7 with respect to the optical axis. It will be easier. In particular, in an optical head used for in-vehicle equipment, the temperature change range of the use environment is extremely wide from high temperature to low temperature. Therefore, when the temperature becomes high or low, due to the difference in linear expansion coefficient between the resin adjustment substrate 7 and the optical chassis 6, the screw 10
A sliding force due to thermal expansion or thermal contraction is generated between the adjustment head 7 or the mounting surface 6a of the optical chassis 6 and the adjustment substrate 7,
The adjustment substrate 7 is likely to be displaced in the X-Y plane direction, and the screw 10 is likely to be loosened.

The present invention solves the above-mentioned problems of the prior art. It is possible to adjust the support of the optical element in each of the three-dimensional directions with a simple structure, and to fix the fixed part (optical It is an object of the present invention to provide an optical element fixing device capable of relieving stress due to a difference in linear expansion coefficient between a chassis) and a support body of the optical element.

[0010]

According to the present invention, in a fixing device for an optical element, a support for supporting an optical element is fixed after being adjusted in position with respect to the fixing portion, and elastically deformed radially in the fixing portion. Possible pins are fitted, the support is inserted into the pin, the position of the support is adjusted, and then the support is fixed to the pin. For example, a mounting hole having an inner diameter larger than the diameter of the pin or a notched portion having a movement allowance with respect to the pin is formed in the support, and the mounting hole or notched portion is inserted into the pin, The position of the support body is adjusted in the axial direction and / or in the plane orthogonal to the axis of the pin, and then the support body and the pin are fixed to each other.

In the above, the support may be provided with a solderable metal portion at a portion through which the pin is inserted, and the support and the pin may be fixed by soldering.

The optical element of the present invention is, for example, a light receiving element (pin photodiode) used in an optical head, and the support body is a metal substrate on which the light receiving element is mounted (a film-like wiring board or the like is attached to the surface thereof). Or a resin printed board on which a wiring pattern is formed. Alternatively, the support may be like a case in which an optical element such as a light receiving element is housed.

The pin which is elastically deformable in the radial direction is a so-called spring pin having a score line in the axial direction. Fitting holes are formed in one or a plurality of places on the mounting surface of the fixed-side optical element such as the optical chassis, and the pins are press-fitted into the fitting holes. The fitting hole is formed with a diameter smaller than the outer diameter of the pin in the free state, and the pin is elastically contracted and press-fitted into the fitting hole. Therefore, it is easy to attach the pin, and even if the inner diameter of the fitting hole is finished with a rough tolerance, the pin is securely press-fitted without causing rattling in the fitting hole. Fixed.

A support body such as a substrate for supporting the optical element is provided with a mounting hole (or notch) having an inner diameter slightly larger than the outer diameter of the pin, and the mounting hole (or notch) serves as the fixing portion. It is inserted into the pin that is press-fitted. By moving the support along the axial direction of the pin, and by moving the support by the gap corresponding to the difference between the outer diameter of the pin and the inner diameter of the mounting hole, the support can be moved in three dimensions with respect to the fixed part. It can be fixed by adjusting the position in the direction. Although it is possible to use an adhesive as a fixing means for the support and the pin, the solderable metal part provided on the support and the surface-treatable pin for soldering are fixed by the soldering operation. Preferably. By using this soldering, the support and the pin can be easily fixed to each other in a short time after the position adjustment of the support is completed.

Since a pin that is elastically deformable in the radial direction such as a spring pin is used for fixing the optical element, the fixing portion is formed of a material, such as an aluminum alloy, which has a large amount of expansion and contraction due to temperature change. Even if it is, the pin elastically follows the change in the diameter of the fitting hole due to expansion or contraction. Therefore, no matter what temperature environment the pin is attached to the fixed portion, the pin is not loosened, and therefore the pin is not inclined with respect to the fixed portion.

Further, when a difference in linear expansion coefficient between the support of the optical element and a fixed portion such as an optical chassis causes a difference in deformation amount between the support and the fixed portion due to expansion or contraction, the pin and the support are supported. At the fixed portion with the body, the difference in the amount of deformation can be absorbed by elastic deformation of the pin in the radial direction. Therefore, a large stress does not act on the adhesive between the pin and the support or the fixing means for soldering, and the deterioration of the fixed part and the reduction of the fixing force due to the adhesive or soldering are less likely to occur, and as a result, the pin due to changes in temperature environment The positional displacement of the support body with respect to the optical element is less likely to occur, and the positional displacement of the optical element with respect to the optical axis is less likely to occur.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing a fixing structure of a light receiving element with respect to an optical chassis of an optical head, as one structural example of a fixing device for an optical element of the present invention. The optical chassis 16 of the optical head H shown in FIG. 1 is die cast from an aluminum alloy, a zinc alloy or the like, and the optical chassis 16 is a laser diode which is the light emitting element (light emitting means) shown in FIG. 1, beam splitter 2,
It is equipped with a reflecting mirror 3, an objective lens 4, and a correction drive mechanism for operating the objective lens in the focus correction direction and the tracking correction direction.

The optical chassis 16 is provided with a mounting surface 16a for supporting the light receiving element 15 which is an example of the optical element of the present invention, and the return light from the disc that has passed through the beam splitter 2 is (a). Light is detected by the light receiving portion (pin photodiode light receiving portion) 15a of the light receiving element 15 through the through hole 16c from the direction of the return path shown. In FIG. 1, the optical axis of the return light is indicated by O.

The light receiving element 15 is mounted and fixed on an adjustment substrate 17 as a support for supporting the light receiving element 15. In the configuration example shown in FIG. 1, a part of an adjustment substrate 17 which is an example of a support is mainly composed of a plate material 18 made of, for example, an aluminum alloy and made of the same material as the optical chassis 16, and the surface of the plate material 18 is insulated. Resin film (resist material film) 19
And a wiring pattern made of a conductor such as copper foil is formed on the surface of the resin film 19.
Since the adjustment board 17 is formed mainly of the same aluminum alloy as the optical chassis 16, there is almost no difference in expansion or contraction dimension between the optical chassis 16 and the adjustment board 17 due to temperature change, which will be described later. Deformation force and stress due to temperature change at the fixing portion between the pin 20 and the adjustment substrate 17 are less likely to occur.

A notch 17a is formed in the adjustment substrate 17, and the resin film 1 is provided on the outer periphery of the notch 17a.
On the surface of 9, the land portion of the wiring pattern is formed. The light receiving element 15 as an example of the optical element is located in the cutout portion 17a, and the terminal 15b extending from the light receiving element 15 is fixed to the land portion by soldering. The lead portion 22 of the flexible printed board is joined to the surface of the adjustment board 17. The wiring pattern formed on the surface of the resin film 19 and the wiring pattern on the surface of the lead portion 22 are electrically connected to each other by soldering, and the conduction path of the terminal 15b is located outside the optical head H by the lead portion 22. Guided to the circuit board. The lead portion 22 is formed on the surface of the plate material 18 such as an aluminum alloy.
A flexible printed board integral with the above may be attached, and a land portion and a wiring pattern to which the terminals 15b are soldered may be formed on the flexible printed board.

In addition, at two places on the left and right of the adjustment board 17,
A mounting hole 17b penetrating the plate member 18 is formed, and a fixed land portion 17c located on the outer periphery of the mounting hole 17b is formed on the surface of the resin film 19. The fixed land portion 17c is formed of the same conductor film as the wiring pattern and is provided independently of the wiring pattern without being electrically connected. This fixed land portion 17c
Is a metal portion which is soldered and fixed to a pin 20 described later. The inner diameter of the mounting hole 17b is the pin 2
It is set sufficiently larger than the diameter dimension of zero. The mounting surface 16a of the optical chassis 16 has fitting holes 16b, 16
b is formed, and the pins 20 are press-fitted into the fitting holes 16b and 16b, respectively.

FIG. 2 is an enlarged perspective view of the pin. The pin 20 is a spring pin formed in a cylindrical shape by a material 20b having a strong elastic force such as stainless steel, and has a split groove (slit) 20a formed in the axial direction, and has a diameter larger than the diameter dimension D in the free state. It is possible to elastically shrink in the direction. This material such as stainless steel 20
Copper plating 20c is applied to the surface of b, and the surface is treated so that it can be soldered. Solder plating 2 on the surface
0d is applied to prevent oxidation of the layer of the copper plating 20c.

FIG. 3 (A) is a partial front view showing the insertion relationship between the adjusting board 17 and the pins 20, and FIG. 3 (B) shows the press-fitted state of the pins 20 and the optical chassis 16 and the adjusting board 17 and the pins 20. It is sectional drawing of the BB line which shows the insertion relationship of. The hole diameter DS of the fitting holes 16b, 16b formed in the optical chassis 16 is slightly smaller than the outer diameter D of the pin 20 in the free state, and DS <D. The difference between D and DS is pin 20
And a press-fitting margin of the fitting hole 16b. Due to this press-fitting margin, the pin 20 is firmly fitted and fixed to the mounting surface 16 a of the optical chassis 16. Further, when the use environment temperature becomes high or low and the fitting hole 16b of the optical chassis 16 expands or contracts, the diameter of the pin 20 elastically follows this expansion or contraction, and the slack of the pin 20 or , Mounting surface 16
The vertical deviation with respect to a is less likely to occur. Note that an adhesive may be injected into the fitting hole 16b in order to further firmly fix the pin 20 and the fitting hole 16b.

Mounting holes 17b formed in the adjusting board 17,
17b is inserted into the pins 20 and 20. FIG. 3 (A)
As shown in (B), the hole diameter DL of the mounting hole 17b is formed larger than the outer diameter D of the pin 20 (DL> D). The difference between the diameters D and DL is the adjustment range of the optical axis shift of the adjustment substrate 17 in the XY plane. Optical chassis 16
Is fixed by a jig, and the adjustment board 17 is held by an adjustment jig.
The mounting holes 17b, 17b are inserted into the pins 20, 20. An inspection reflection member (or inspection disk) is installed on the optical axis of the objective lens 4 of the optical head H, laser light is emitted from the laser diode 1, and the returned light is received by the light receiving unit 15a, and the received light is received. The adjustment jig is slightly moved while observing the output. First, by moving the adjustment board 17 in the axial direction (Z direction) of the pin 20, the light receiving portion 15a
Is adjusted in the optical axis O direction, and the mounting hole 17b
By finely moving the adjustment substrate 17 within the XY plane within the adjustment range due to the difference between the hole diameter of the hole and the diameter of the pin 20, the optical axis shift of the light receiving portion 15a with respect to the optical axis O of the return light is adjusted. .

After the above adjustment is completed, the fixed land portion 17c of the adjustment board 17 at the optimum position and the pin 20 are fixed by soldering. As a result, the mounting of the light receiving element 15 can be completed, and the optical head H can be removed from the jig. Since the adjustment board 17 is fixed after the adjustment is completed by soldering the land portion 17c and the pin 20, the work of fixing the pin 20 and the adjustment board 17 is easy, and the adjustment board 17 after the position adjustment is completed. Can be fixed in a short time, the time from completion of adjustment to removal from the jig can be shortened, and workability can be improved.

In the above configuration example, the adjustment substrate 17 is mainly composed of the plate material 18 such as an aluminum alloy, but when the mounting hole 17b expands or contracts in a high temperature environment or a low temperature environment, the radial direction of the pin 20 is increased. This expansion or contraction can be absorbed by the elastic deformation of, so that excessive stress does not act on the soldered portion, and problems such as solder peeling hardly occur. Further, the stress acting on the adjustment board 17 is also reduced.
Since the solder fixing portion is stabilized and unnecessary force is not applied to the adjustment substrate 17, the light receiving portion 15a is less likely to be displaced with respect to the optical axis O after the product is completed.
Product reliability can be improved.

If the adjustment board 17 is made of a resin material such as PCB or glass epoxy,
Due to the difference in the linear expansion coefficient between the adjustment substrate 17 and the optical chassis 16, the difference in the amount of expansion or contraction between the optical chassis 16 and the adjustment substrate 17 becomes large in a high temperature or low temperature environment. Also in this case, this difference can be absorbed by the elasticity of the pin 20, and an excessive force does not act on the soldered portion. Furthermore, the adjustment substrate 17 and the pin 20 may be fixed to each other with an adhesive such as an ultraviolet curable material. As described above, since the deforming force acting on the fixed portion of the pin 20 due to the temperature change is absorbed by the elastic deformation of the diameter of the pin 20,
The peeling of the adhesive is less likely to occur.

[0028]

As described above, in the present invention, the pin that is elastically deformable in the radial direction is used to support the support body that supports the optical element in a positionally adjustable manner. Therefore, there is no occurrence of slack in the portion where the pin is attached to the fixed portion, and no inclination of the pin. Also, it is possible to prevent unreasonable force from acting on the fixed part such as soldering or adhesion between the support and the pin, deterioration of the fixed part due to temperature change does not occur, and displacement of the optical element with respect to the optical axis does not easily occur. Become. In particular, the use of soldering as the means for fixing the support and the pin simplifies the work for fixing the support.

Furthermore, by making it possible to move the support body in each of the three-dimensional directions with respect to the pin,
With a simple structure, it is possible to adjust the position of the optical element in the three-dimensional direction.

[Brief description of drawings]

FIG. 1 is a perspective view showing a fixing device of a light receiving element with respect to a chassis of an optical head as one configuration example of the present invention,

FIG. 2 is an enlarged perspective view of a pin,

3A and 3B show a state in which an adjustment substrate supporting a light receiving element is fixed to a fixing portion, FIG. 3A is a partial front view showing the relationship between pins and an adjustment substrate, and FIG. Cross section of the line,

FIG. 4 is a configuration diagram showing an outline of an internal structure of an optical head,

FIG. 5 is a partial perspective view of an optical head showing an example of a conventional fixing device for a light receiving element,

[Explanation of symbols]

 15 Light receiving element 15a Light receiving part (pin photodiode receiving part) 16 Optical chassis 16a Mounting surface 16b Fitting hole 16c Through hole 17 Adjustment board (optical element support) 17b Mounting hole 17c Fixed land part 20 pin H Optical head

Claims (2)

[Claims] 1. A fixing device for an optical element, in which a support for supporting an optical element is fixed after being adjusted in position with respect to a fixing portion, wherein a pin elastically deformable in a radial direction is fitted to the fixing portion. A fixing device for an optical element, wherein the support is fixed to the pin after the support is inserted into the pin and the position of the support is adjusted. 2. The fixing device for an optical element according to claim 1, wherein the support is provided with a solderable metal portion in a portion where the pin is inserted, and the support and the pin are fixed by soldering. .