JP2005115257A - Light source device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that a variance in pressurizing force due to the error of dimension is excessively large in a conventional fitting of Peltier element because the variance in the dimension is comparatively large, although a temperature control is necessary in a light source device using an LD, the Peltier element is used to absorb generated heat, the Peltier element is fixed by adhering in a conventional method which has a problem causing a high cost due to the plant and the processing time, and the certain amount of pressurizing force is necessary for fixing without adhering. <P>SOLUTION: The light source device is so composed that a face of the Peltier element 16 is made to be in close contact with an LD holder 11c at the rear end of the light source unit 11 which is mounted on an optical system holder 12. The other face of the Peltier element 16 is abutted on the rising part 12c of the end part of the optical system holder 12, the large diameter part 11b of the light source unit 11 is pressurized to the side of the Peltier element with a leaf spring 21 provided on the horizontal face part of the optical system holder 12. Thus, the pressurizing force within a predetermined range is available allowing the variance in the thickness of the Peltier element and in the elastic force of the leaf spring. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a light source device used in a scanning optical system such as an image forming apparatus, an image reading apparatus, and a measuring instrument. In particular, the present invention relates to a device that devised a method of assembling a light source unit and a cooling element.

FIG. 6 is a diagram illustrating an example of a scanning optical system as an example of an optical apparatus.
In the figure, reference numeral 1 denotes a light source device, 2 denotes a light modulation device, 5 denotes a folding mirror, 7 denotes an imaging lens for surface tilt correction, 8 denotes a polygon mirror, 9 denotes an fθ lens system, 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, is corrected by the surface tilt correction imaging lens 7 via the folding mirror 5, and enters the polygon mirror 8. The light beam enters the fθ lens system 9 while the reflection direction is continuously changed by the rotation of the polygon mirror 8, and reaches the scanned surface 10 made of a photoconductor to form a latent image. The light source unit 1 uses a semiconductor laser or the like as a light source.

A light source using a semiconductor laser (hereinafter abbreviated as LD) pays particular attention to temperature control because its light output changes with temperature. Actually, since the LD light source itself generates heat, cooling is usually performed. Therefore, heat from the light source is propagated to the outside as quickly as possible, and cooling is performed using a cooling element such as a Peltier element (see, for example, Patent Document 1). Therefore, a member for attaching the LD, that is, an LD holder is made of a material having high thermal conductivity, and the LD and the cooling element are in close contact with the member.
In general, a copper-based material is used as a material having high thermal conductivity. Among them, pure copper has the highest thermal conductivity, but pure copper is used as a copper alloy because of its low mechanical strength. Chromium copper is suitable as an LD holder because of its excellent mechanical strength and high thermal conductivity.

FIG. 7 is a diagram showing an example of a conventional light source device.
In the figure, reference numeral 11 is a light source unit that has been adjusted for an optical system, 12 is an optical system holder, 13 is an LD, 14 is a collimating lens, 15 is a collimating lens holder, 16 is a Peltier element, 17 is a heat dissipation sheet as a heat dissipation member, 18 Denotes a heat radiating member, and H denotes a heat transfer path.
Conventionally, a method in which the Peltier element 16 is adhered to a surface to be radiated and fixed with an adhesive is used. However, the bonding process is time consuming and increases the equipment cost. In the figure, a light source unit 11 is attached to an optical system holder 12 to form a light source device 1. In the light source unit 11, the LD 13 is attached to the LD holder 11c, and the LD holder 11c is attached to the large diameter portion 11b via a heat insulating member 11d. The heat generated from the LD is hardly transmitted to the large diameter portion 11b because the heat insulating sheet is present. A Peltier element 16 is in close contact with the lower part on the back side of the LD holder 11c, and is in pressure contact with the heat radiating member 18 via the heat radiating sheet 17. Since the heat radiating member 18 is further attached to the optical system holder 12, the heat transfer path from the Peltier element 16 to the optical system holder 12, which is the final heat radiating member, is considerably long, and the heat dissipation efficiency is not so high.
In this example, the contact pressure of the Peltier element is determined by the accuracy control of the parts, and the dimensional error is released by deformation of the heat radiation sheet 17 made of a resilient material such as rubber. Actually, the heat radiation sheet 17 may be attached to either surface of the Peltier element 16. If necessary, you can attach both.
Thus, if not fixed by adhesion, the Peltier element is a certain pressure that does not disturb the positional accuracy of the optical system with respect to the cooled member and the heat radiating member, for example, a Peltier element of approximately 15 mm square, It is necessary to adhere with a strength of about several tens to several hundred grams.

By the way, there is a problem that Peltier elements generally cannot be made with a very high outline accuracy. In particular, if there is a variation in dimensions regarding its thickness, depending on how it is pressed, there will be a large variation in the pressure to be in close contact, and the desired cooling effect may not be obtained, there is a risk of destroying the Peltier element, or It may upset the accuracy of the optical system. In a specific example of dimensions, in the case of a Peltier element approximately 15 mm square and about 5 mm thick, the thickness variation is about ± 0.2 mm. Therefore, if the heat dissipation sheet is too thin, the deformation rate becomes too large, so it is necessary to use a sheet that is somewhat thick.
In Patent Document 1, the interval is adjusted by inserting a spacer between two substrates sandwiching a Peltier element.

Japanese Patent Laid-Open No. 11-281906 (page 7, FIG. 4)

  The problem to be solved is to provide a configuration in which the pressure contact force of the Peltier element to the LD holder does not change greatly even if there is a manufacturing error in the thickness of the Peltier element.

The invention according to claim 1 includes a light source unit having a light source attached to the light source holder, an optical system that deforms a diameter of a light beam from the light source, and an optical system holder that holds the light source unit. In the light source device, one surface of the Peltier element for absorbing heat generated from the light source is opposed to the light source holder, the other surface of the Peltier element is opposed to a part of the optical system holder, and the Peltier element is The two holders are pressed against each other with a pressing force within a predetermined range.
According to a second aspect of the present invention, in the light source unit of the first aspect, the light source unit is configured to be movable in the optical axis direction of the light source unit with respect to the optical system holder. The pressing force in the predetermined range is generated by movement in the axial direction.
According to a third aspect of the present invention, in the light source device according to the second aspect, the contact portion between the light source unit and the optical system holder has a reduced sliding frictional resistance.
According to a fourth aspect of the present invention, in the light source device according to any one of the first to third aspects, a heat radiation means is interposed between at least one of the two holders and the Peltier element. .

The invention according to claim 5 is the light source device according to claim 4, wherein the heat dissipating means is a heat dissipating sheet.
A sixth aspect of the present invention is the light source device according to the fourth aspect, wherein the heat dissipating means is heat dissipating grease.
The invention according to claim 7 is a light source unit having a light source attached to a light source holder, an optical system for deforming a beam diameter from the light source, an optical system holder for holding the light source unit, and the light source. In a light source device having a pressing slider that can be moved close to and away from the unit, one surface of the Peltier element for absorbing heat generated from the light source is opposed to the light source holder, and the other surface of the Peltier element is used as the pressing slider. The pressing slider is pressed against the Peltier element with a pressing force within a predetermined range.
According to an eighth aspect of the present invention, in the light source unit according to the seventh aspect, the pressing slider is configured to be movable in an optical axis direction of the light source unit, and the predetermined slider is moved by moving the pressing slider in the optical axis direction. A pressurizing force within a range is generated.
According to a ninth aspect of the present invention, in the light source device according to the seventh or eighth aspect, a heat radiation means is interposed between at least one of the pressing slider and the light source holder and the Peltier element.

According to a tenth aspect of the present invention, in the light source device according to the ninth aspect, the heat radiation means is a heat radiation sheet.
The invention according to claim 11 is the light source device according to claim 9, wherein the heat dissipating means is heat dissipating grease.
According to a twelfth aspect of the present invention, in the light source device according to any one of the first to eleventh aspects, the pressurizing force in the predetermined range is generated by a biasing member provided in the optical system holder. Features.
According to a thirteenth aspect of the present invention, in the light source device according to any one of the first to eleventh aspects, the pressure within the predetermined range is applied by an urging member provided in an optical device to which the light source device is to be attached. It is characterized by generating.
According to a fourteenth aspect of the present invention, in the light source device according to the thirteenth aspect, the light source unit to which the pressure within the predetermined range is applied is fixed to the optical system holder.
According to a fifteenth aspect of the present invention, in the light source device according to any one of the first to eleventh aspects, the pressurizing force in the predetermined range is provided on a jig configured to allow the light source device to be attached. The light source unit is generated by a biasing member, and the light source unit is fixed to the optical system holder in that state.
According to a sixteenth aspect of the present invention, in the light source device according to any one of the twelfth to fifteenth aspects, the biasing member is a coil-type compression spring.
According to a seventeenth aspect of the present invention, in the light source device according to any one of the twelfth to fifteenth aspects, the urging member is a leaf spring.
According to an eighteenth aspect of the present invention, in the light source device according to any one of the first to seventeenth aspects, the light source is a semiconductor laser.
According to a nineteenth aspect of the present invention, there is provided an image forming apparatus using the light source device according to any one of the first to eighteenth aspects.
According to a twentieth aspect of the present invention, there is provided an image reading device using the light source device according to any one of the first to eighteenth aspects.

  According to the present invention, even if a Peltier element having a certain range of manufacturing error in thickness is used, the Peltier element can be brought into contact with the heat radiating member with a pressurizing force within a predetermined range, preventing the element from being destroyed and providing a desired cooling effect Can be obtained.

  When attaching the light source unit whose optical axis has been adjusted to the optical system holder, one surface of the Peltier element is brought into close contact with the light source holder at the rear end of the light source unit, and the other surface of the Peltier element is attached to the rising portion of the optical system holder. Make contact. A leaf spring having one end fixed to the optical system holder presses the light source unit backward, and pressurizes the Peltier element with a force that is in a predetermined pressure range.

FIG. 1 is a diagram for explaining an embodiment of the present invention.
In the figure, reference numeral 19 denotes a pressing member. Other symbols are the same as those in FIG.
The light source unit 11 has a small-diameter portion 11a including an optical system such as a compressor lens and a large-diameter portion 11b including a collimator lens cell. An LD holder 11c is further in close contact with the end surface of the large-diameter portion. Eccentricity and optical axis adjustment are complete. The optical system holder 12 has two rising portions 12a and a hole portion 12b. The small diameter portion 11a of the light source unit enters between the two rising portions 12a, and the large diameter portion 11b and the lower portion of the LD holder are holes. Drop into part 12b. At this time, the Peltier element 14 is brought into close contact with the rear surface of the LD holder. In this state, a margin is provided so that the light source unit can be moved slightly in the optical axis direction. The contact portion between the light source unit 11 and the optical system holder 12 should have a low sliding friction resistance as much as possible. Therefore, the contact surface may be subjected to a surface treatment for reducing the frictional resistance, a material having a low frictional resistance may be used, or the contact area between the two may be reduced.
The optical system holder 12 is provided with a rising portion 12c at the end of the hole 12b, and serves as a Peltier element contact surface.

The light source unit 11 is pushed with a predetermined amount of force in the direction of the rising portion 12c using any of the urging means described with reference to FIGS. 2 and 3, and the LD holder 11c is moved to the rising portion 12c via the Peltier element 16. Adhere with a predetermined pressure. With this configuration, the heat generation energy due to the lighting of the LD flows to the optical system holder 12 through the LD holder 11c, the Peltier element 16, and the rising portion 12c, and cools the LD. In order to stabilize the contact, a heat radiating member 17 may be sandwiched between the LD holder 11c and the Peltier element 16, or between the Peltier element 16 and the rising portion 12c, or between both. In particular, when the elasticity of the heat dissipating member is not required, it can be replaced with a heat dissipating sheet with less elasticity or heat dissipating grease.
The effect is the same even if the Peltier element 16 is attached to the rising portion 12c side, or the holding state is released after applying a pressing force while temporarily holding the Peltier element 16c by hand or other methods.

FIG. 2 is a partial cross-sectional view for explaining the first embodiment of the present invention.
In the figure, reference numeral 20 denotes a pressure spring as an urging member.
One end of the coil-type pressure spring 20, also called a compression spring, is attached to the optical device body to which the light source device 1 is to be attached. When the light source device 1 is attached at a predetermined position, the pressure spring 20 is compressed by a necessary amount. Then, the other end of the pressure spring 20 is brought into contact with a spring receiving surface (not shown) provided in the light source device 1. The light source unit 11 is pushed rearward (leftward in the figure) on the optical system holder 12, and the Peltier element 16 contacts the rising portion 12c with a pressure within a predetermined range. For example, it is approximated considering the case where the pressing force is set to 200 gram weight ± 20%, that is, 160 to 240 gram weight. Assuming that the manufacturing error of the pressure spring 20 itself is ± 10%, the remaining 10% is an error that can be allowed for the variation in the thickness of the Peltier element. As described above, since the variation in the thickness of the Peltier element is ± 0.2 mm, it is only necessary to generate a pressure of 200 grams with a spring deformation amount of 2 mm or more. Actually, the amount of force generated with the same amount of deformation changes from 180 to 220 grams, so that the ratio of the error that can be allowed for the variation in the thickness of the Peltier element varies slightly between the plus side and the minus side. Taking this into consideration, it is sufficient to generate a 200 gram weight force with a spring deformation amount of 2.2 mm or more.

The above description has been made with the configuration in which the pressure spring 20 is left as it is in the optical device main body. However, the light source unit 11 is pressed against the optical system holder 12 with a pressure within a predetermined range with a set screw (not shown) or the like. A method of fixing both is also possible. When the fixing is completed, the pressure spring 20 becomes unnecessary and may be removed. Therefore, the pressure spring 20 does not remain in the optical device main body as the final product. With this method, the light source device is not attached with the optical device after being attached to the optical device, but is applied with a separate jig to fix the light source unit 11 to the optical system holder. You may bring it in.
However, if the light source unit 11 and the optical system holder 12 are fixed in this way at room temperature, the temperature of the members on both sides including the Peltier element increases due to conduction heat due to the temperature increase of the light source during actual use. I'm worried about changes in the pressure due to expansion. As a countermeasure, one method is to place the temperature of the related member in an actual use state, and apply a pressure within a predetermined range in that state to fix the light source unit. When the temperature is returned to room temperature, there is no shrinkage that makes the applied pressure zero. In another method, an elastic heat-dissipating sheet is placed adjacent to the Peltier element, and the amount of change in the thickness direction of the Peltier element due to temperature change is absorbed. Since the change in the thickness direction of the Peltier element due to the temperature difference between the normal temperature and the actual use temperature is a slight amount on the order of μm, no problem occurs regardless of which of the above two methods is used.

FIG. 3 is a partially broken cross-sectional view for explaining a second embodiment of the present invention.
In the figure, reference numeral 21 denotes a leaf spring as an urging member, and 22 denotes a mounting screw.
The leaf spring 21 is attached to the horizontal surface portion of the optical system holder 12 by an attachment screw 22 and presses the edge of the large diameter portion of the light source unit backward. In the case of this configuration, the light source device itself exerts pressure on the Peltier element.
The amount of force to be given to the leaf spring 21 is essentially the same as that of the pressurizing spring 20 shown in the first embodiment.

FIG. 4 is a partial cross-sectional view for explaining a third embodiment of the present invention.
In the figure, reference numeral 23 is a pressing slider, 24 is a set screw, 25 is a pressing spring as an urging member, and 26 is a pressing unit.
This embodiment is different from the first and second embodiments in that the member that contacts the back surface of the Peltier element 16 is not a part of the optical system holder 12 but a pressing slider 23 that is a separate member.
The light source unit 11 is fixed to the optical system holder 12. The pressing slider 23 is loosely fixed to the set screw 24 at the long hole portion, and is pressed toward the light source unit 11 by the pressurizing spring 25 to constitute the pressing unit 26. The whole or a part of the pressing unit portion 26 is attached on the extension of the optical system holder 12 or attached to the optical device main body.
In this embodiment, the set screw 24 can be tightened by the pressurizing spring 25 in a state where a predetermined pressure is applied to the Peltier element. When the set screw 24 is tightened, the pressure spring 25 is not necessary and may be removed.
As another method, the set screw 24 can be used only for guiding in the horizontal direction in the figure without being used to fix the pressing slider 23. In this case, the pressure spring 25 cannot be removed. However, even when the optical unit expands or contracts in the horizontal direction due to a temperature change or the like, the pressing slider 23 moves to the left and right accordingly, and a large pressure change occurs. It will not be.

FIG. 5 is a partial cross-sectional view for explaining a fourth embodiment of the present invention.
In the figure, reference numeral 27 denotes a leaf spring as an urging member, 28 denotes a mounting screw, and 29 denotes a pressing unit.
In the present embodiment, the pressure spring 25 in the third embodiment is replaced with a leaf spring 27, which is the same in principle.
Although the light source of the present invention is not particularly illustrated, a multi-laser diode can be similarly applied as long as it is a semiconductor laser. Or if it is a solid light emission light source with heat_generation | fever like LED, it is applicable similarly.

It is a figure for demonstrating embodiment of this invention. It is a partial sectional view for explaining Example 1 of the present invention. (Example 1) It is a partial sectional view for explaining Example 2 of the present invention. (Example 2) It is a partial sectional view for explaining Example 3 of the present invention. Example 3 It is a partial sectional view for explaining Example 4 of the present invention. (Example 4) It is a figure which shows the example of the scanning optical system as an example of an optical apparatus. It is a figure which shows an example of the conventional light source unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source device 11 Light source unit 12 Optical system holder 13 LD
16 Peltier elements 20 and 25 Pressure springs 21 and 27 Leaf spring 23 Press slider

Claims (20)

  Heat generated from the light source in a light source device having a light source attached to the light source holder, an optical system that deforms a light beam diameter from the light source, and an optical system holder that holds the light source unit One surface of the Peltier element for absorbing the Peltier element is opposed to the light source holder, the other surface of the Peltier element is opposed to a part of the optical system holder, and both holders are placed within a predetermined range with the Peltier element interposed therebetween. A light source device that is pressed with pressure.   2. The light source unit according to claim 1, wherein the light source unit is configured to be movable in the optical axis direction of the light source unit with respect to the optical system holder, and the light source unit moves within the predetermined range by movement of the light source unit in the optical axis direction. A light source device that generates pressure.   3. The light source device according to claim 2, wherein the contact portion between the light source unit and the optical system holder has a reduced sliding frictional resistance.   4. The light source device according to claim 1, wherein a heat radiation unit is interposed between at least one of the holders and the Peltier element.   5. The light source device according to claim 4, wherein the heat radiating means is a heat radiating sheet.   5. The light source device according to claim 4, wherein the heat radiating means is heat radiating grease.   A light source unit having a light source attached to the light source holder, an optical system that deforms a diameter of a light beam from the light source, an optical system holder that holds the light source unit, and a pressure slider that can be moved closer to and away from the light source unit The one surface of the Peltier element for absorbing heat generated from the light source is opposed to the light source holder, the other surface of the Peltier element is opposed to the pressing slider, and the pressing slider is moved to the Peltier element. A light source device that presses against an element with a pressing force within a predetermined range.   8. The light source unit according to claim 7, wherein the pressing slider is configured to be movable in the optical axis direction of the light source unit, and generates a pressing force in the predetermined range by movement of the pressing slider in the optical axis direction. A light source device.   9. The light source device according to claim 7, wherein a heat radiating means is interposed between at least one of the pressing slider and the light source holder and the Peltier element.   The light source device according to claim 9, wherein the heat radiating means is a heat radiating sheet.   The light source device according to claim 9, wherein the heat radiating means is heat radiating grease.   12. The light source device according to claim 1, wherein the pressing force in the predetermined range is generated by a biasing member provided in the optical system holder.   12. The light source device according to claim 1, wherein the pressing force in the predetermined range is generated by an urging member provided in an optical device to which the light source device is to be attached. .   14. The light source device according to claim 13, wherein the light source unit to which the pressure within the predetermined range is applied is fixed to the optical system holder.   12. The light source device according to claim 1, wherein the pressurizing force in the predetermined range is generated by an urging member provided on a jig configured to allow the light source device to be attached. A light source device, wherein the light source unit is fixed to the optical system holder.   16. The light source device according to claim 12, wherein the biasing member is a coil type compression spring.   The light source device according to claim 12, wherein the biasing member is a leaf spring.   The light source device according to claim 1, wherein the light source is a semiconductor laser.   An image forming apparatus using the light source device according to claim 1. An image reading apparatus using the light source device according to any one of claims 1 to 18.

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