JP4504001B2 - Light source unit, optical scanning device, image reading device, and image forming device - Google Patents

Description

  The present invention relates to a light source device that guides and uses a light beam emitted from a light source to an optical system. In particular, the present invention relates to a light source device that does not cause misalignment after centering the light source with respect to the holder.

FIG. 8 is a diagram showing an example of a scanning optical system.
In the figure, reference numeral 1 denotes a light source device, 2 denotes a light modulation device, 5 denotes a deflection device, 7 denotes a surface tilt correction optical system, 8 denotes a rotating polygon mirror, 9 denotes an fθ lens, and 10 denotes a surface to be scanned.
The light beam emitted from the light source device 1 is modulated by the image information in the light modulation device 2, changed in direction by the deflection device 5, continuously reflected in the reflection direction by the rotary polygon mirror 8, and scanned by the fθ lens 9. 10 is scanned at a constant speed. By scanning the surface to be scanned 10 in a direction perpendicular to the paper surface, image information is read or a latent image corresponding to the image information is formed. Such an apparatus is used in an image forming apparatus such as a copying machine, a facsimile, a printer, a digital laboratory, or the like. It can also be used as a reading device by receiving reflected light from the surface to be scanned without using a light modulation device.

FIG. 9 is a diagram illustrating an example of the configuration of the light source device.
In the figure, reference numeral 11 is a semiconductor laser (hereinafter referred to as LD), 12 is an LD holder, 13 is a heat insulating member, 14 is a collimating lens, 15 is a collimating lens cell, 16 is a lens cell holder, 17 is a compressor lens barrel, 18 is A lens barrel holder, C is a ring-shaped auxiliary member, U1 is a first unit, and U2 is a second unit.
In the first unit U <b> 1, a collimating lens cell 15 that holds the collimating lens 14 is screwed from one side of the lens cell holder 16. The LD holder 12 is attached to the other side of the lens cell holder 16 via a heat insulating member 13. The LD holder 12 has a through hole 12a having a counterbore near the center, and the LD 11 is attached via an auxiliary member C dropped into the counterbore, and is pressed and stopped by a pressing plate 12b. .

The reason why the LD 11 cannot be directly attached to the LD holder 12 is that the LD holder 12 is made of a metal material, for example, a material having a relatively high thermal conductivity, such as chromium copper, for heat dissipation. This is because they want to be electrically insulated. Therefore, an insulating ceramic is selected as the auxiliary member C. Depending on the composition of the ceramic, various types of ceramics having a thermal conductivity ranging from a small value to a very large value can be obtained. Therefore, a ceramic having a relatively high thermal conductivity is used here for heat dissipation. On the other hand, the LD holder 12 performs cooling by bringing a Peltier element or the like (not shown) into contact therewith. Table 1 shows the thermal conductivity of various materials. In this table, pure copper shows extremely high values, but pure copper is not used much because of its mechanical strength.
In the second unit U2, a compressor lens barrel 17 is placed on a barrel holder 18, and is fixed by a holding member (not shown).
The first unit U1 and the second unit U2 are fixed so as to fit a part of the collimating lens cell 15 and a part of the lens cell holder 16 into the lens barrel holder 18 and are fixed by screws or the like (not shown) to complete the light source device 1. .

Table 1

FIG. 10 is a schematic diagram for explaining the relationship between the LD and the hole of the LD holder in the temperature change. The figure (a) is a figure which shows a state when assembled | attached at normal temperature, and the figure (b) is a figure which shows a state when it becomes low temperature especially. In the figure, the change in the gap is exaggerated.
In the figure, symbol A indicates an arrow indicating the moving direction of the auxiliary member C.
It is assumed that the LD 11 is almost fully accommodated in the auxiliary member C. The size of the auxiliary member C is given a margin with respect to the hole 12a of the LD holder 12.
Assume that the auxiliary member C in which the LD is fitted is assembled in the hole 12a of the LD holder 12 and both are eccentric as shown in FIG. Nevertheless, the optical axis can be aligned by adjusting the position of the LD holder with respect to the collimating lens 14.
If the optical axis alignment is completed in this state, it is assumed that a temperature drop occurs when the apparatus is left unattended. Since chrome copper has a considerably larger linear expansion coefficient than ceramic, the degree of contraction between the two is greatly different. In FIG. 2B, the solid line indicates the shape after contraction, and the alternate long and short dash line and the broken line indicate the positions of the hole 12a and the auxiliary member C during assembly. That is, when the hole 12a of the LD holder 12 contracts, the auxiliary member C is pushed in one direction as indicated by the arrow A, and as a result, the LD 11 is shifted from the initial position.

  Although not the optical axis deviation of LD, the structure which prevents the optical axis deviation of the collimating lens by a temperature change is proposed (for example, refer patent document 1). In this configuration, the collimating lens holder is formed in a conical shape or a pyramid shape and is used by being fitted into an inner barrel having a conical inner peripheral surface. According to this configuration, the optical axis shift of the lens due to a temperature change can be prevented, but the LD is in direct contact with the metal outer barrel, and the problem of electrical insulation is not considered. Patent Document 1 does not touch on prevention of optical axis misalignment of the LD by electrically insulating the LD and the LD holder.

JP-A-10-193680 (3rd, 4th page, FIG. 3)

  The problem to be solved is that if the centering of the LD holder and the LD is completed at the time of completion of the unit, the center deviation between the two will not occur even if the environmental temperature changes thereafter.

The invention described in claim 1 is a light source unit using a semiconductor laser or a light emitting diode as a light source, and includes a light source holder, an auxiliary member, and a pressing plate.
The light source holder has a through hole, and has a counterbore portion concentric with the through hole, that is, has a common central axis and has a diameter larger than that of the through hole. The bottom face of the counterbore part is the through direction of the through hole (the central axis above)
Orthogonal to
The auxiliary member has a flat plate shape, and a light source is attached to the central portion of the flat plate surface. The light source holder has a fitting portion that can be dropped with a gap at room temperature, and is made of an electrically insulating material. .
The light source holder and the auxiliary member have different linear expansion coefficients.
The holding plate is attached to the flat surface portion of the light source holder, has a spring property, presses the auxiliary member and the light source against the light source holder at a plurality of portions, and presses the auxiliary member against the bottom surface of the spot facing portion.

The cross-sectional shape orthogonal to the penetration direction of the shape of the spot facing portion and the outer peripheral portion of the fitting portion is circular. The outer periphery of the spot facing is a cylindrical surface. The outer peripheral part of the fitting part of an auxiliary member is also a cylindrical surface.
The counterbore portion and the fitting portion, the cylindrical faces are opposed, between the two cylindrical surfaces are combined as such cylindrical faces does not contact the "ring-shaped gap of a constant width".
A flexible filler is injected into the ring-shaped gap so that the injection amount is uniform.
The gap width of the ring-shaped gap due to thermal deformation of the light source holder and holding member accompanying temperature change is absorbed by elastic deformation of the filler, and the light source does not shift with respect to the center of the spot facing. That is, the light source does not shift in the radial direction of the spot facing.
The filler in the light source unit according to claim 1 can be an elastic adhesive (Claim 2), and the filler is also a gel that has a low viscosity when injected and changes to a predetermined viscosity or more over time. (Claim 3).
The material of the light source holder in the light source unit according to any one of claims 1 to 3 can be chrome copper (claim 4).

The material of the auxiliary member in the light source unit according to any one of claims 1 to 4 may be ceramic (claim 5). Moreover, the auxiliary member in the light source unit according to any one of claims 1 to 5 can be made of an electrically insulating material (claim 6).
A light source device of the present invention is a for optical scanning, characterized by using the light source unit according to any one of claims 1-6 (Claim 7).
An optical scanning device of the present invention is an optical scanning device using the light source device according to claim 7 (claim 8). The image reading device of the present invention is an image reading device using the optical scanning device according to claim 8 (claim 9).
The image forming apparatus of the present invention is an image forming apparatus using the optical scanning device according to claim 8 (claim 10).

In a state where the through hole of the light source holder of the light source unit used in the light source device and the light source are aligned , a flexible adhesive or the like is injected between the auxiliary member integrated with the light source and the light source holder. By injecting so that the amount becomes equal, the center deviation due to temperature change does not occur even in actual use.

The main part of the light source unit is made of chrome copper and has an LD holder having a through hole, and a ring-shaped auxiliary member made of ceramic having an outer shape in which the LD is integrally attached and can be dropped into the hole part at room temperature. A holding plate attached to the LD holder and having a spring property to press the auxiliary member, and the shape of the counterbore part concentric with the through hole and the shape of the auxiliary member outer shape are both circular, Are assembled so as to be concentric to form an LD unit, and then an adhesive is injected around the auxiliary member so that the injection amount becomes equal .

FIG. 1 is a partially omitted view of a light source holder portion to which the present invention is applied. FIG. 2A is a side sectional view, and FIG.
In the figure, reference numeral 20 denotes an LD unit, 21 denotes an LD, 22 denotes an auxiliary member, 23 denotes an LD holder, 24 denotes a pressing plate, 25 denotes a set screw, and G denotes a gap.
The LD 21 is dropped into a counterbore portion 23b provided around the through hole 23a of the LD holder 23 through the auxiliary member 22, and is contacted and pressed by the claw portion 24a of the holding plate 24 having a spring property. Stopped by 25. The LD 21 and the auxiliary member 22 are fitted with almost no gap, and in the following description, both are treated as one body.
The auxiliary member 22 and the counterbore 23b are each configured to have a size such that a slight gap G is generated at room temperature. As shown in FIG.1 (b), the cross-sectional shape (shape on the cross section parallel to drawing) of the outer peripheral part of the auxiliary member 22 is circular, and the shape of the spot facing part 23b is also circular.
As shown in FIG. 1A, the bottom surface of the counterbore portion 23b is orthogonal to the penetration direction of the through hole 23a, and the auxiliary member 22 has a flat plate shape. The outer peripheral portion of the spot facing portion 23b is a cylindrical surface with the penetrating direction as an axis, and the outer peripheral portion of the auxiliary member 22 is also a cylindrical surface.
The present invention has the above-described configuration in which the gap portion G between the auxiliary member 22 and the counterbore portion 23b is made uniform by any method, and as a result, the LD 21 and the through hole 23a are aligned. By injecting the filler uniformly into the gap portion G, there is a feature that the center deviation does not occur with respect to the subsequent temperature change or the like.
As shown in FIG. 1B, in the centered state, the circular shape that is the shape of the spot facing portion 22b and the circular shape that is the cross-sectional shape of the fitting portion are concentric, and the gap portion G is The cylindrical surfaces face each other so as not to contact each other to form a “ring-shaped gap having a constant width”.

In the state where the alignment is completed, the set screw of the pressing plate 24 is tightened so that the auxiliary member 22 does not move. Then, a fluid adhesive is injected into the equalized gap portion G, for example, like an injection needle, so that the surrounding injection amount becomes equal. Since the claw part 24a of the pressing plate 24 covers a part of the gap part G, the adhesive cannot be directly injected into the part, but the bottom part of the claw part 24a is also filled by the fluidity of the adhesive. When the adhesive swells from the gap portion G, it adheres to the holding plate 24 and may give an unequal force to the auxiliary member 22.
The adhesive may be of a type that loses fluidity over time and cures, or a type that cures by ultraviolet irradiation or the like. In either case, an elastic adhesive such as a rubber that retains a certain degree of elasticity even in a cured state is suitable for the present invention.
A gel-like material can be used instead of the adhesive. It is desirable that the gel-like material has a viscosity showing a certain degree of fluidity when injected, and has a viscosity with almost no fluidity when left as it is. For example, some silicon-based gels have a higher viscosity due to evaporation of the alcohol content, so that it is preferable to use such a gel. The state having almost no fluidity means a viscosity that does not flow out due to the weight of the gel.
Hereinafter, the elastic adhesive or the gel material is collectively referred to as a filler.

A situation when a temperature change occurs in a state where a filler is put in the gap G will be described.
The case where the LD holder 23 is made of chrome copper and the auxiliary member 22 is made of ceramic will be described as an example.
First, consider the case where the temperature rises from room temperature.
FIG. 2 is a partial cross-sectional view showing the relationship between the gap and the filler when the temperature rises.
In the figure, reference numeral 26 denotes a filler. In the figure, the gap is exaggerated.
Since the coefficient of linear expansion of chrome copper is larger than that of ceramic, the gap G increases as the overall shape of the gap G increases as the temperature rises. Since the filler 26 itself also has a considerably large linear expansion coefficient, it expands, and the bonded portion between the chrome copper and the bonded portion between the ceramics are not separated from each other, so that the auxiliary member 22 is always uniform throughout the temperature rise. Receive a good compressive force. However, since the filler 26 is flexible, excessive pressure escapes in the direction of the open end face (upward direction in the figure), and the pressure that actually pushes the auxiliary member 22 in the center direction does not increase so much.
As a result, even if the temperature rises, the misalignment between the LD holder 23 and the auxiliary member 22 does not occur. Therefore, the LD 21 is not misaligned.

Next, consider a case where the temperature is lower than room temperature.
FIG. 3 is a partial cross-sectional view showing the relationship between the gap and the filler when the temperature drops.
Contrary to the above, the width of the gap G decreases as the overall shape of the gap G decreases. The filler shrinks faster than the chrome copper shrinkage, but the chrome copper bond and the ceramic bond do not separate from each other, so the auxiliary member is always uniformly negative throughout the temperature drop. Under pressure. Actually, the negative pressure is reduced by causing a so-called shrinkage in which the open end face of the filler descends.
As a result, even if the temperature falls, the misalignment between the LD holder 23 and the auxiliary member 22 does not occur. Therefore, the LD 21 is not misaligned.
Even when the temperature returns to room temperature after the temperature rises or returns to room temperature after the temperature falls, the positional relationship between the LD holder 23 and the auxiliary member 22 does not change, and the original state is correctly reproduced. It was found that reproducibility was very good even in repeated experiments with temperature cycling.

4 and 5 are partial cross-sectional views for explaining the shape of the spot facing portion of the LD holder.
In FIG. 4, a chamfered portion 23c is provided around the upper surface of the spot facing portion 23b. The adhesive 26 is injected conservatively so as not to fill the chamfer. In this way, even when the filler protrudes due to the pressure at the time of temperature rise, the surface area is increased by the chamfered portion 23c, so that the amount of protrusion does not increase so much. There is no risk of contact.
In FIG. 5, the notch part 23d is provided in the bottom part of the counterbore part 23b. If the notch 23d has a certain depth, when the filler is injected, air is confined in the notch 23d and the filler does not penetrate deeply. When the temperature rises in this state, the cut portion becomes one of pressure escape portions, and a part of the filler further enters the cut portion while compressing the enclosed air. Combined with the escape of pressure to the upper surface, it becomes easy to eliminate excessive compression force. The effect is further enhanced by combining the shape of FIG. 4 and the shape of FIG.

FIG. 6 is a diagram showing an example of a method for aligning the LD and the through hole. FIG. 2A is a side sectional view, and FIG. The outer shape of the LD holder 23 is omitted in FIG.
In the figure, reference numeral 30 denotes a centering jig, 31 denotes an outer cylinder, and 32 denotes an intermediate cylinder.
FIG. 7 is a perspective view showing a centering jig. This method can be applied when the gap G is relatively large.
The auxiliary member 22 integrated with the LD 21 is dropped into the counterbore portion 23b, positioned so that the claw portion 24a of the pressing member 24 presses the back surface of the LD 21, and temporarily fixed with the set screw 25 shown in FIG. Unadjusted LD unit is made.
In the centering jig 30, a relatively thin outer cylinder 31 and a slightly thick middle cylinder 32 are closely fitted, and both can move in the longitudinal direction of the cylinder. Both have claw portions 31a and 32a at positions corresponding to each other at the tip of the tube. The claw portions 31a and 32a are formed to have substantially the same length along the circumference, for example, centering on a position that divides the circumference into three equal parts, and the sides opposite to the close contact surfaces have the same inclination angle. An inclined surface is formed. When the tips of both claw portions are aligned, the isosceles portion of a substantially isosceles triangle is formed with the outer shape of the claw portions 31a and 32a in the cross section.
A long hole 31 b is formed in the outer cylinder 31 in the longitudinal direction of the cylinder, and a slide pin 32 b that fits into the long hole 31 b is planted in the middle cylinder 32. For this reason, both cylinders are restricted so that they can move in the longitudinal direction of the cylinders but cannot rotate in the circumferential direction.

Loosen the set screw of the unadjusted LD unit, shift the outer cylinder 31 of the aligning jig 30 in the direction of the claw portion 31a, and insert the three claw portions 31a evenly between the auxiliary member 22 and the counterbore portion 23b. To do. The inclined surface portion of the claw portion 31a is inserted to a position that matches the inner diameter of the counterbore portion 23b and stops. At this time, the inner periphery of the outer cylinder 31 is concentric with the spot facing portion 23b.
The virtual circle formed by the three claw portions 31a is set to be smaller than the minimum diameter of the allowable error range of the spot facing portion 23b at the tip of the claw portion and larger than the maximum diameter of the same range at the base of the claw portion.
Next, the middle cylinder 32 is slid to the outer cylinder 31, and the claw portion 32a is inserted into the gap. At this time, if the auxiliary member 22 is not concentric with the counterbore portion 23b, a force is generated that hits the auxiliary member 22 in the center direction by hitting the claw portion 32a first. When all the three claw portions 32a come into contact with each other, the claw portions 32a cannot be inserted any more, and the middle cylinder 32 cannot move any more. At this time, the auxiliary member 22 is concentric with the outer periphery of the middle cylinder 32. If there is no play between the outer cylinder 31 and the middle cylinder 32, the auxiliary member 22 and the spot facing portion 23b are concentric as a result.
The claw portions 31a and 32a are formed very thin because they are inserted into the gap portion G. However, since the claw portions 31a and 32a have a slight length along the circumferential portion of the cylinder, the tips of the claw are not straight but have a slight curvature. It has a circular arc. Therefore, when the claw portion 31a hits the spot facing portion 23b, the three claws come into contact evenly without the claw portion 31a being deformed. The same applies to the claw portion 32a.
Even when both the claw portions are inserted to the maximum depth, the cylindrical end surface portion other than the claw portion of the centering jig 30 is configured not to contact the claw portion 24a of the pressing member. Although not shown, if necessary, an escape portion may be formed so that the claw portion 24a does not hit the cylindrical end surface portion.

Next, another example in which the auxiliary member and the LD holder are aligned will be described.
This method uses the difference between the linear expansion coefficients of the two. This method can be applied when the gap G is relatively small.
In order to simplify the explanation, it is assumed that the auxiliary member 22 is made of ceramic and the LD holder 23 is made of chrome copper.
As described above, chrome copper has a very large linear expansion coefficient, whereas ceramic has a small linear expansion coefficient. Therefore, when temperature changes, the size of the gap G between the auxiliary member 22 and the LD holder 23 is large. Changes.
When assembling the LD unit 20, the position of the LD 21 relative to the LD holder 23, that is, the concentricity with the through hole 23a, may not be considered at all.
When the LD unit 20 is completed, it is attached to the lens cell holder via a heat insulating material as the next step, and centering with the collimating lens is performed. In the present invention, before that, the centering of the LD 21 and the through hole 23a ( Simply referred to as alignment).

The LD unit 20 is left in an atmosphere of a predetermined temperature. The predetermined temperature includes the lowest temperature in the installation environment temperature range to be guaranteed by the device, for example, lower than −25 ° C., and the lowest temperature that may occur during transportation, for example −30 ° C. In some cases, the temperature may be lower.
The LD holder 23 contracts greatly at a low temperature. Of course, the auxiliary member 22 also contracts, but the extent is considerably smaller than the former. The gap between the spot facing portion 23b and the auxiliary member 22 decreases due to the difference between the shrinkage amounts of the two. The size of the gap at room temperature is determined so that the gap is exactly 0 at the predetermined temperature. At this time, since the contact surfaces of both members are slipped, the contact portion between the auxiliary member 22 and the LD holder 23 is configured so that the frictional resistance is particularly small. Methods for reducing the frictional resistance include reducing the contact area and performing a surface treatment for reducing the frictional resistance, but if both are used in combination, the effect is still greater.
Conversely, the LD 21 and the pressing plate 24 are configured so that the frictional resistance is increased.

As described with reference to FIG. 10, even if the auxiliary member 22 is eccentrically attached to the counterbore portion 23b, the auxiliary member 22 contacts somewhere on the inner periphery of the counterbore portion 23b as the temperature decreases. After that, it receives the pressure from the contact point and is moved in the direction in which the centers coincide. Since the contact surface between the auxiliary member 22 and the LD holder 23 is configured to reduce the frictional resistance, the auxiliary member 22 is moved in the central direction without a large resistance even when the above pressure is applied. At this time, the claw portion 24a of the pressing plate 24 comes into contact with the LD 21 and exhibits a large frictional resistance. However, since the force due to contraction of the member is much larger, the claw portion 24a can stop the movement of the LD. Can not.
If the entire LD unit 20 is substantially equal to the ambient temperature, the outer periphery of the auxiliary member 22 and the inner periphery of the spot facing portion 23b coincide with each other, and therefore, both are concentric at this point.

Next, the LD unit 20 is returned to room temperature. At this time, if it is brought into the room temperature suddenly, dew condensation occurs, partial temperature unevenness occurs in the LD unit 20, and distortion occurs temporarily inside the unit, which is not preferable.
When the auxiliary member 22 and the LD holder 23 rise from the minimum temperature, a gap is generated again between them. At this time, the contact surface between the two has a small frictional resistance, but the frictional resistance between the LD 21 and the claw portion 24a is large. When the temperature drops, a forcing force is applied from the inner periphery of the spot facing 23b toward the LD 21 toward the center, so that the LD 21 moves against the frictional resistance of the claw 24a. Comparable forcing does not work. Accordingly, the LD 21 cannot move relative to the claw portion 24a.
The magnitude of the frictional resistance mentioned here is relative, so there is no appropriate value for how much each should be. However, when returning to normal temperature, if the difference between the two forces is too small, there is no guarantee that the position of the LD 21 will be maintained. For this reason, the frictional force on the claw portion 24a side is equal to the frictional force on the LD holder 23 side. I want more than twice.

The holding plate 24 has a disk-like outer shape, and has three set screw holes and three claw portions 24a, and is configured to have the same shape when rotated by 120 ° as a whole with respect to the center of the disk. . When the pressing plate 24 is attached to the LD holder 23, the center of the disc is configured to coincide with the center of the through hole 23a. The through hole 23a and the counterbore 23b are formed by simultaneous machining and are always concentric.
In such a configuration, when the presser plate 24 is attached to the LD holder 23, the center of the disk and the center of the through hole 23a are always aligned even if the temperature changes. This is the same even when the linear expansion coefficients of the two do not match. However, if the linear expansion coefficients of the two are significantly different, a large stress is applied to the set screw portion due to temperature change, and therefore it is not preferable.

  Since the presser plate 24 itself expands and contracts due to temperature changes, the tip of the claw portion 24a also changes forward and backward toward the center of the disc. Since this change occurs evenly in the three claws, if the pressure for pressing the LD 21 of the claw portion 24a is equal, it will not be a force to move the LD 21. The set screw 25 and the claw portion 24a are arranged in a positional relationship that divides the circumference into three equal parts. However, this is not limited to two equal parts or four equal parts. If it is equal, it does not matter. In short, when the claw portion 24a advances and retreats due to a temperature change, it is sufficient that a biased force that shifts the center position of the LD does not occur. That is, the arrangement may be such that the resultant force acting on each claw portion 24a is zero. If this relationship is maintained, the outer shape of the holding plate 24 does not have to be circular. For example, it may be a rectangle including a square. Instead, the condition that the plurality of set screws 25 are equidistant with respect to the center of the through hole 23a and that are equiangularly spaced from each other is not changed.

Further, although the set screw 25 and the claw portion 24a are shown to have the same phase with respect to the circumference, the present invention is not necessarily limited to this. For example, even if both are configured with a phase shift of 60 °, the effect is exactly the same.
The LD 21 and the through hole 23a of the LD holder 23 remain concentric even when the LD unit that has been centered by this method is returned to room temperature. In this state, even if there is a further temperature change, there is basically no misalignment, but if the filler is injected into the gap G as described above, then the optical axis shift with respect to the temperature change can be further prevented. Be certain.
This LD unit generates excessive pressure because the gap G is not yet zero at the lowest temperature in the installation environment temperature range that the apparatus should guarantee or the lowest temperature that may occur during transportation. And there is no destruction of the device.

As described above, the example in which the LD holder 23 is made of chrome copper and the auxiliary member 22 is made of ceramic has been described.
However, in the case where the auxiliary member 22 has a larger linear expansion coefficient than the LD holder 23, for example, when the LD holder is formed of a ceramic material and the auxiliary member is formed of chrome copper, for the purpose of centering the two Is set to a temperature higher than room temperature.
Although the description has been given in the case of the LD as the light source, it is not limited to the LD as long as the shapes are similar. For example, the present invention can be applied even to an LED. In this case, all the LDs in the above description may be interpreted by replacing them with LEDs or generally light sources.
Further, the method includes a first member having a circular hole (including a counterbore) and a second member having at least a part of a circular outer shape that can be fitted into the hole. In general, the present invention can be applied to unit alignment in the case where the linear expansion coefficients of both members are different. The second member in this case corresponds to an auxiliary member in which the LD in the LD unit is fitted .

It is a partial abbreviation figure of the light source holder part to which the present invention is applied. It is a fragmentary sectional view which shows the relationship between the clearance gap at the time of temperature rise, and a filler. It is a fragmentary sectional view which shows the relationship between the clearance gap at the time of temperature fall, and a filler. It is a fragmentary sectional view for demonstrating the shape of the spot facing part of LD holder. It is a fragmentary sectional view for demonstrating the shape of the spot facing part of LD holder. It is a figure which shows an example of the method of aligning LD and a through-hole. It is a perspective view which shows a centering jig | tool. It is a figure which shows an example of a scanning optical system. It is a figure which shows an example of a structure of a light source device. It is a schematic diagram explaining the relationship between LD and the hole of LD holder in a temperature change.

Explanation of symbols

20 LD unit 21 LD
22 Auxiliary member 23 LD holder 24 Holding plate 26 Filler

Claims (10)

A light source unit using a semiconductor laser or a light emitting diode as a light source,
A light source holder having a through hole, concentric with the through hole in a planar portion, having a diameter larger than the through hole, and a counterbore portion perpendicular to the through direction of the through hole;
A light source is attached to the center part of the flat plate surface, and a spot facing part of the light source holder,
An auxiliary member having a fitting part that can be dropped with a gap at room temperature;
A pressing plate that is attached to the flat surface portion of the light source holder, has a spring property, presses the auxiliary member and the light source at a plurality of sites, and presses the auxiliary member against the bottom surface of the counterbore portion; ,
Both the peripheral surface portion of the spot facing portion and the outer peripheral portion of the fitting portion are cylindrical surfaces,
The light source holder and the auxiliary member have different linear expansion coefficients,
The cylindrical surface of the counterbore part and the cylindrical surface of the fitting part are combined so as to form a ring-shaped gap with a constant width so that the cylindrical surfaces do not contact each other,
The filler having flexibility is injected into the ring-shaped gap so that the injection amount is uniform,
The change of the gap width of the ring-shaped gap due to the thermal deformation of the light source holder and the auxiliary member due to the temperature change is absorbed by the elastic deformation of the filler, and the light source does not shift with respect to the center of the counterbore part. A featured light source unit. The light source unit according to claim 1,
The light source unit, wherein the filler is an elastic adhesive. The light source unit according to claim 1 or 2,
The light source unit, wherein the filler is a gel-like material that has a low viscosity when injected and changes to a predetermined viscosity or more with time. The light source unit according to any one of claims 1 to 3,
The light source unit is characterized in that the material of the light source holder is chromium copper. The light source unit according to any one of claims 1 to 4,
A light source unit, wherein the material of the auxiliary member is ceramic. The light source unit according to any one of claims 1 to 5,
A light source unit, wherein the auxiliary member is made of an electrically insulating material. A light source device for optical scanning, wherein the light source unit according to any one of claims 1 to 6 is used.   An optical scanning device using the light source device according to claim 7.   An image reading apparatus using the optical scanning device according to claim 8.   An image forming apparatus using the optical scanning device according to claim 8.

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