JP2008227815A - Heat sink structure for image sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat sink structure for an image sensor, which efficiently discharges light to be emitted from a light source to an outer part in a small space, and considers dust proof property. <P>SOLUTION: The heat sink structure for the image sensor includes: a light guide extending in a direction of reading width of original; holders arranged in both the end parts of the light guide, having holes in flat boards, and holding the light guide by inserting the end parts of the light guide to a part at one end of each hole; a metallic board including the light source in a space part at the other end of the holes in each holder and arranged along the wall surfaces of the holders; heat sink boards arranged at the opposite side of the holders via the metallic board, extended in an original feeding direction along the wall surface of the metallic board, and bent in the direction of reading width of original; leaf springs arranged along the wall surface of each heat sink board, having elastic parts arranged partially on the opposite side of the metallic board via the heat sink boards; and a resin case body to be brought into pressure contact with the elastic parts of the leaf spring and integrally fixing the holders, the metallic board, the heat sink boards, and the leaf springs from both the sides. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a heat dissipation structure for an image sensor equipped with an LED light source or the like.

  With an increase in output of an LED light source used in an illumination system mounted on an image sensor configured with a small space, there is a demand for a structure for efficiently dissipating heat generated from the light source. For example, in FIG. 7 of JP 2002-218162 A (see Patent Document 1), a heat radiating member 108g is provided on the opposite side of the light guide 108c via the LED 108b, and the heat radiating member 108g has a substantially U-shaped cross section. By using this leaf spring, the space K is formed inside the U-shape. The space portion K includes a pair of flat plate portions 108g1 and 108g2 opposed via the space portion K and a connection portion 108g3 connecting the flat plate portions 108g1 and 108g2.

FIG. 2 (see Patent Document 2) of Japanese Patent Laid-Open No. 5-56214 shows an LED array 21 that illuminates a document on a support 1 cut into a metal extrusion material such as an aluminum alloy that integrally supports a reading system. An image sensor is disclosed in which the interior of the support 1 forms two substantially independent spaces 30 and 31 and the LED array 21 is accommodated on the space 30 side.

Japanese Patent Laid-Open No. 2002-218162 (FIG. 7)

Japanese Patent Laid-Open No. 5-56214 (FIG. 2)

However, although the thing of patent document 1 is connecting with the housing | casing 108f using the elastic U-shaped leaf | plate spring and improving the thermal radiation effect, there exists a movable part of leaf | plate spring in the vicinity of LED108b. Depending on the movable state of the leaf spring, there is a problem that foreign matter is allowed to enter the light source side, and light emission is blocked by the foreign matter, resulting in unstable light emitted from the light source.

  The one described in Patent Document 2 uses a conductive material such as a metal for the support 1 to improve the shielding effect against harmful radio waves, and the reading system has an integrated structure, and independent spaces 30 and 31 are provided. Although the adverse effect due to dust is also taken into consideration by forming, the support 1 is a metal casing, and there is a problem that it becomes an expensive image sensor as a result of having a low degree of freedom in external design and requiring cutting. .

  The present invention has been made to solve the above-described problems, and provides a heat dissipation structure for an image sensor that efficiently emits light emitted from a light source to the outside in a small space and considers dustproofness. Objective.

  A heat dissipation structure for an image sensor according to a first aspect of the present invention includes a light guide that extends in the reading width direction of a document, and both ends of the light guide, provided with holes in a flat plate, A holder for holding the light guide by inserting an end of the light guide into a part on one end side, a light source is disposed in the space on the other end side of the hole of the holder, and a wall surface of the holder A metal plate installed along the metal plate, and a heat radiating plate extending in the document transport direction along the wall surface of the metal plate on the opposite side of the holder via the metal plate and bent in the document reading width direction And an elastic part in a part on the opposite side of the metal plate through the heat radiating plate, a plate spring installed along the wall surface of the heat radiating plate, and the elastic part of the plate spring, The holder, the metal plate, the heat radiating plate and the leaf spring are integrally formed from both sides. It is obtained by a resin casing to wear.

  According to a second aspect of the present invention, there is provided a heat dissipation structure for an image sensor, wherein a slit portion that penetrates the heat sink extending in the document transport direction in the housing, the heat sink and the housing that penetrate the slit portion, A rubber covering the gap is added.

  As described above, according to the heat dissipation structure of the image sensor according to claim 1, the LED light source is mounted on the metal plate, the heat sink is placed on the opposite side of the LED light source mounting surface, and the heat sink is removed from the housing. Since the protruding heat sink is bent and extended in the longitudinal direction, Joule heat generated by the LED light source can be quickly diffused to the outside, and a heat dissipation structure for an image sensor with high heat dissipation can be obtained. There is an effect.

  According to the heat dissipation structure of the image sensor according to claim 2, dust is mixed into the sealed space inside the casing because the gap between the casing and the heat dissipation plate that protrudes outside through the slit portion of the casing is covered with rubber. Therefore, there is an effect that the reading quality can be maintained without deteriorating the optical performance of the image sensor due to the floating matter that obstructs illumination.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to FIG. FIG. 1 is an exploded perspective view of the overall configuration of the image sensor according to the first embodiment. In FIG. 1, reference numeral 1 denotes an upper housing (resin housing) made of plastic resin or the like for housing components to be mounted on the image sensor, 1 a is an image sensor mounting portion, 1 b is a slit portion of the upper housing 1, and 1 c is a resin-molded rubber (rubber) attached to the slit portion 1 b of the upper housing 1. Reference numeral 2 denotes a lower casing (resin casing) which is provided in the lower portion of the upper casing 1 and forms a sealed space in combination with the upper casing 1, and 3 is a transparent plastic material or transparent glass material disposed in the sealed space. The light guide 4 that transmits light in the main scanning direction (in the document reading width direction) is provided at both ends of the light guide 3, and the light guide 3 enters the light guide 3 from the end of the light guide 3. An LED unit assembling unit 5 equipped with LEDs for irradiating light is a document conveyed in the sub-scanning direction of the image sensor. In addition, the LED unit assembly part 4 uses the unit of the structure which comprised components in the mutually opposite direction as a pair.

  Reference numeral 6 denotes a condensing lens that concentrates and illuminates the light emitted from the light guide 3 at the reading position of the document 5 located above, and 7 denotes a rod lens array (lens array) that focuses the light reflected from the document surface. is there. Reference numeral 8 denotes a sensor substrate on which the light converged by the rod lens array 7 is mounted on the lower housing 2 and mounted with a sensor IC in which a large number of light receiving portions are linearly arranged. The sensor substrate 8 outputs a photoelectric conversion signal photoelectrically converted by the sensor IC as an image signal from a connector (not shown) or the like. In the drawings, the same reference numerals indicate the same or corresponding parts.

FIG. 2 is a configuration exploded perspective view of the LED unit assembly. In FIG. 2, 10 is a light source such as an LED chip, 11 is an LED chip 10 mounted on a metal member such as a phosphor bronze plate, and one electrode of the LED chip 10 is wire-bonded to an individual electrode terminal (not shown). A metal plate 12 has a hollow portion on a flat plate, accommodates the LED chip 10 in a space, and inserts each end of the light guide 3 to fix the light guide 3 at both ends.

13 is provided along the flat portion on the opposite side of the metal plate 11 on which the LED chip 10 is mounted and is bent to extend in the main scanning direction (longitudinal direction), and 14 is provided outside the heat sink 13. A plate spring, and an elastic member such as a phosphor bronze plate is punched or bent to provide an elastic portion (bent portion) 14a, and the upper housing 1 is pressed against the elastic portion 14a to thereby form a metal plate 11, The holder 12 and the heat radiating plate 13 are integrated and fixed by pressure contact (crimping). Note that the metal plate 11, the holder 12, the heat radiating plate 13, and the leaf spring 14 are positioned by a protruding portion 12 a provided on the holder 12 and fixed by pressure bonding.

FIG. 3 is a side view and perspective view of the LED unit assembly portion 4. In FIG. 3, 15 is a resin-molded rubber (rubber) that is fixed near the bent portion of the heat radiating plate 13 and has a slit in the center. In combination with the resin-molded rubber (rubber) 1c provided in the upper housing 1, The heat sink 13 penetrates between the slits 1c. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts.

FIG. 4 is a detailed perspective view of the configuration of the LED unit assembly. In FIG. 4, the heat sink 13 crimped along the metal plate 11 is composed of the upper housing 1 provided with the slit portion 1b and the rubbers 1c and 15 in close contact with each other. It passes through the gap, bends outside the upper housing 1, and extends in the longitudinal direction of the image sensor. In the figure, the same reference numerals as those in FIGS. 1 to 3 denote the same or corresponding parts.

  Next, the operation will be described with reference to FIGS. Light emitted from the LED unit assembly portion 4 enters from the side surface of the end portion of the light guide 3, propagates in the main scanning direction while being totally reflected in the light guide 3, and is gradually scattered in the light guide 3. The condenser lens 6 is irradiated with illumination light that is irregularly reflected by a pattern or the like and is uniform throughout. The condenser lens 6 has a focal point substantially on the surface of the original, and the light is concentrated on the reading position of the original 5 being conveyed.

  The light reflected by the image information on the original surface is converged by the rod lens array 7, and the reflected light converged by the rod lens array 7 is photoelectrically converted by the light receiving portion of the sensor substrate 8. The photoelectric conversion output preferably has a wide dynamic range. When the photoelectric conversion output is driven at high speed, the drive current of the light source 10 increases. For example, when the light source 10 is pulse-driven, when the loss voltage of the light source is 1.5 V in addition to the amount of heat generated by the light, a driving current of about 50 mA is necessary, so that a loss power of about 75 mW is generated. Furthermore, since the light source 10 is mounted with LED light sources of a plurality of emission colors such as RGB at the same time and is driven at the same time in addition to being lit in a single color, even greater Joule heat is generated.

  In order to effectively dissipate the Joule heat, the LED chip 10 needs to be in direct contact with the metal surface and the heat conducted to the metal surface needs to be dissipated outside the image sensor. Therefore, although the metal plate 11 is housed inside, the heat dissipation plate 13 brought into contact with the metal plate 11 is extended along the metal plate 11 and extended to the outside of the housing 1 of the image sensor. improves.

  Further, in order to suppress the image sensor to a compact shape and capacity, the heat radiating plate 13 extending to the outside is bent in the longitudinal direction. Further, in order to secure a sealed space of the image sensor and prevent the entry of dust and the like from the outside, rubber 1c, 15 is provided around the heat radiating plate 13 protruding from the first housing 1 at the boundary between the sealed space and the external space. cover.

  As described above, according to the heat dissipation structure of the image sensor according to the first embodiment, the light source 10 is mounted on the metal plate 11, and the heat dissipation plate 13 is placed on the opposite side of the LED light source 10 mounting surface of the metal plate 11, Since the heat radiating plate 13 protrudes from the housing 1 to the outside and the protruded heat radiating plate 13 is bent and extends in the longitudinal direction, the Joule heat generated in the light source 10 is dissipated outside the image sensor, and the heat dissipation efficiency A high heat dissipation structure for an image sensor can be obtained.

Further, since the gap between the housing 1 provided with the slit 1b and the heat radiating plate 13 that penetrates the slit 1b and protrudes to the outside is covered with rubber 1c and 15, dust is mixed into the sealed space inside the housings 1 and 2. Therefore, the optical performance of the image sensor can be maintained.

In the first embodiment, the upper housing 1 and the lower housing 2 are separated from each other, and the slit portion 1b is provided in the upper housing 1. However, a part of the lower housing 2 is disposed on the upper housing 1 side. Even if it is extended and a slit is provided at that portion, the same effect can be obtained.

In the first embodiment, the upper casing 1 and the lower casing 2 are separated from each other. However, the mounting portion 1a of the upper casing 1 is provided at a different position such as the central portion of the casing, and the end of the casing is arranged. When a part is inserted into the sealed space from the side of the part, the same effect can be obtained even when the upper housing 1 and the lower housing 2 are integrally formed.

1 is an exploded perspective view of the overall configuration of an image sensor according to Embodiment 1 of the present invention. It is a structure expansion perspective view of the LED unit assembly part of the image sensor by Embodiment 1 of this invention. It is the side view and perspective view of the LED unit assembly part of the image sensor by Embodiment 1 of this invention. It is a structure detailed perspective view of the LED unit assembly part of the image sensor by Embodiment 1 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Case (resin case), 1a Mounting part, 1b Slit part, 1c Rubber (resin molding rubber), 2 Case (resin case), 3 Light guide, 4 LED unit assembly part, 5 Document, 6 Collection Optical lens, 7 Rod lens array (lens array), 10 Light source (LED chip), 11 Metal plate, 12 Holder, 12a Protruding part, 13 Heat sink, 14 Leaf spring, 14a Elastic part (bending part), 15 Rubber (resin) Molding rubber).

Claims (2)

A light guide that extends in the reading width direction of the document and both ends of the light guide, provided with a hole in the flat plate, and an end of the light guide on a part of one end of the hole A holder for holding the light guide by insertion, a metal plate disposed along the wall surface of the holder with a light source disposed in the other end side space of the hole of the holder, and via the metal plate And a heat sink extending in the document transport direction along the wall surface of the metal plate on the side opposite to the holder and bent in the document reading width direction, and opposite to the metal plate via the heat sink A plate spring having an elastic part in a part on the side and installed along the wall surface of the heat radiating plate, and the elastic part of the plate spring are pressed against each other, and the holder, the metal plate, the heat radiating plate, and the plate spring Heat dissipation of an image sensor with a resin housing that integrally attaches to both sides Elephants. A slit portion that penetrates the heat radiating plate extending in the document conveyance direction and a rubber that covers a gap between the heat radiating plate that penetrates the slit portion and the housing are added to the housing. The heat dissipation structure for an image sensor according to claim 1.

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