JP6422031B2 - Illumination apparatus, image reading apparatus, and image forming apparatus - Google Patents

Description

  The present invention relates to an illumination device, an image reading device, and an image forming device, and more particularly to a light source cooling mechanism for reading an image.

  An image reading apparatus generally reads an image on a document by irradiating the document with a light emitting diode (hereinafter referred to as LED) or other light source arranged in the main scanning direction and receiving the reflected light with a line sensor. On the other hand, the demand for higher resolution and higher speed of image reading is a factor in increasing the amount of light that should be emitted by the light source. However, an increase in the amount of light brings about an increase in the amount of heat generated, so cooling of the light source is a problem. To solve such a problem, for example, in the technique of Patent Document 1, a light source support frame made of sheet metal is provided on a carriage housing for scanning by mounting a light source so that the light source support frame is exposed to the outside. An LED light source is installed. Thereby, the light source support frame is functioned as a heat radiating plate to improve the heat radiating effect. The technique of patent document 2 is improving the heat dissipation effect by devising the shape of a heat sink in the structure which cools a heat sink with a ventilation means.

JP 2014-090281 A JP 2008-160582 A

  However, since the technique of Patent Document 1 merely radiates heat from the heat radiating plate exposed to the outside, there is a problem that the limit of the heat radiating effect is low. The technology of Patent Document 2 cools a cooling plate whose shape is devised by a blowing means, but requires a dedicated blowing drive source.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a technique for easily cooling an illumination device of an image reading apparatus.

  The present invention provides an illuminating device used in an image reading device that reads an image on a document by reciprocating. The illumination device includes: a light emitting unit that irradiates light to the document; a light emitting unit substrate on which the light emitting units are arranged in a main scanning direction; a reciprocating direction that is the reciprocating direction; and the main scanning direction. And a pair of cooling plates disposed opposite to each other with the light emitting unit substrate interposed therebetween. The pair of cooling plates has an interval between the pair of cooling plates at a position where the light emitting unit is disposed in the reciprocating direction as a light emitting unit interval, and both ends of the pair of cooling plates in the reciprocating direction. The interval between the light emitting portions is smaller than any of the both end intervals.

  In the illumination device, the light emitting unit substrate may have a metal layer that extends in the reciprocating direction and is thermally coupled to the light emitting unit.

  The present invention provides an image reading apparatus. The image reading apparatus includes the illumination device, a scanning mechanism that reciprocates the illumination device, and an image signal generation unit that receives reflected light from the document and generates an image signal.

  The image reading apparatus further includes an automatic document feeder that automatically conveys a document, a blower that is driven by branching a part of the driving force transmitted to the automatic document feeder, and the scanning mechanism. You may make it provide the control part which controls the said ventilation part. When reading an image using the automatic document feeder, the control unit arranges the scanning mechanism at a predetermined position set in advance for reading an image of the document conveyed by the automatic document feeder. To do. The blower blows air toward the pair of cooling plates of the lighting device arranged at the predetermined position.

  The present invention provides an image forming apparatus. The image forming apparatus includes the image reading device and an image forming unit that forms an image on a print medium based on the image signal generation unit.

  According to the present invention, the illumination device of the image reading device can be easily cooled.

1 is a schematic configuration diagram illustrating an overall configuration of an image forming apparatus 1 according to an embodiment of the present disclosure. 2 shows a light source unit 110 of an image forming apparatus 1 according to an embodiment, FIG. 2A shows a perspective view, and FIG. 2B shows a front view seen in the main scanning direction. FIG. 3A shows a state in which image reading is performed using an automatic document feeder (ADF) 30 in the image forming apparatus 1 according to an embodiment, and FIG. 3A is a schematic configuration diagram of the image forming apparatus 1. FIG. 3B is a perspective view showing the cooling device 150. It is a front view which shows the light source part 110a which concerns on a modification. FIG.

  Hereinafter, modes for carrying out the present invention (hereinafter referred to as “embodiments”) will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing an overall configuration of an image forming apparatus 1 according to an embodiment of the present invention. The image forming apparatus 1 includes a control unit 10, an image reading unit 100, an image forming unit 20, an automatic document feeder (ADF) 30, and a storage unit 40. The image reading unit 100 reads an image from a document and generates image data PD which is digital data. The image forming unit 20 forms and discharges an image on a print medium (not shown) based on the image data PD. The automatic document feeder (ADF) 30 will be described later.

  The control unit 10 includes main storage means such as RAM and ROM, and control means such as MPU (Micro Processing Unit) and CPU (Central Processing Unit). The control unit 10 also has controller functions related to various I / O, USB (Universal Serial Bus), bus, and other hardware such as hardware, and controls the entire image forming apparatus 1.

  The storage unit 40 is a storage device including a hard disk drive or a flash memory that is a non-temporary recording medium, and stores a control program and data for processing executed by the control unit 10.

  The image reading unit 100 includes a light source unit 110 (also called an illumination device), a first reflecting mirror 131, a first carriage 120, a second reflecting mirror 135, a third reflecting mirror 136, and a second carriage 137. , A condenser lens 138, an image sensor 141, and a cooling unit 150. The first reflecting mirror 131 reflects the reflected light L from the document in the direction of the second reflecting mirror 135. The second reflecting mirror 135 reflects the reflected light L in the direction of the third reflecting mirror 136. The third reflecting mirror 136 reflects the reflected light L in the direction of the condenser lens 138. The condenser lens 138 forms an image of the reflected light L on the light receiving surface of the image sensor 141.

  The first carriage 120 is mounted with the light source unit 110 and the first reflecting mirror 131 and reciprocates in the sub-scanning direction S (also referred to as reciprocating direction). The second carriage 137 carries the second reflecting mirror 135 and the third reflecting mirror 136 and reciprocates in the sub-scanning direction S. The first carriage 120 and the second carriage 137 form part of a scanning mechanism controlled by the control unit 10, and the light source unit 110 can scan the document in the sub-scanning direction. As a result, the image sensor 141 outputs an analog electrical signal (also referred to as an image signal) according to the two-dimensional image on the document, and the analog electrical signal is A / D converted to generate image data PD. The image sensor 141 functions as an image signal generation unit.

  FIG. 2 shows the light source unit 110 of the image forming apparatus 1 according to the embodiment. 2A shows a perspective view of the light source unit 110, and FIG. 2B shows a front view of the light source unit 110 viewed in the main scanning direction. In FIG. 2B, the air flow during sub-scanning is also indicated by arrows. The light source unit 110 includes a light emitting unit 112 that is a light emitting diode (LED), a light emitting unit substrate 113 on which the light emitting unit 112 is mounted, a pair of cooling plates 115 and 116, and an optical lens (not shown). doing. The light emitting unit substrate 113 has a plate shape extending in the main scanning direction and the reciprocating direction S. A copper layer 114 that is thermally coupled to the light emitting unit 112 and functions as a heat sink is embedded in the light emitting unit substrate 113. An optical lens (not shown) emits light from the light emitting unit 112 in the sub-scanning direction, deflects it, and irradiates it in the direction of the document (see FIG. 1).

  The pair of cooling plates 115 and 116 have a large thermal conductivity and are made of a lightweight aluminum alloy. The pair of cooling plates 115 and 116 are disposed to face each other across the light emitting unit substrate 113 in a direction perpendicular to both the reciprocating direction S and the main scanning direction. The pair of cooling plates 115 and 116 have a hyperbolic shape (or an arc shape) and are opposed to each other with the following interval. The pair of cooling plates 115 and 116 are opposed to each other at a position where the light emitting unit 112 is disposed in the reciprocating direction S with a light emitting unit interval Cm therebetween. The pair of cooling plates 115 and 116 are opposed to each other at one end in the reciprocating direction S at a first end interval Ce1. The pair of cooling plates 115 and 116 face each other at the second end interval Ce2 at the other end in the reciprocating direction S. The light emitting portion interval Cm is formed to be smaller than both the first end portion interval Ce1 and the second end portion interval Ce2 (also referred to as both end portion intervals).

  The light source unit 110 achieves efficient heat dissipation by two means. The first means is a means for causing the pair of cooling plates 115 and 116 to function as rectifying plates for controlling the air flow. The second means is a means for causing the pair of cooling plates 115 and 116 to function as a heat radiating plate.

  The first means radiates heat from the light emitting unit 112 and the copper layer 114 by an air flow. Specifically, the light source unit 110 reciprocates in the reciprocating direction S during sub-scanning when reading a document. For example, when the light source unit 110 moves to the left in FIG. 2B, the pair of cooling plates 115 and 116 take in air at the interval of the second end portion interval Ce2, and the light emitting unit 112 is disposed. Pour into the interval region of the interval Cm. At this time, since air can be regarded as an incompressible fluid, the air is obtained by multiplying the reciprocating speed VS by the interval of the second end portion interval Ce2 and dividing the flow velocity VA by the interval of the light emitting portion interval Cm. (VA = VS × Ce2 ÷ Cm). Thereby, heat can be effectively removed from the light emitting part 112 and the copper layer 114 with the air having the increased flow velocity.

  The second means radiates heat by radiation from the light emitting unit 112 and the copper layer 114 to the pair of cooling plates 115 and 116. That is, the light emitting unit 112 and the copper layer 114 conduct heat to the cooling plates 115 and 116 by heat radiation. Since the cooling plates 115 and 116 are made of aluminum having a large thermal conductivity, the heat is transmitted to the whole and can be dissipated from the whole. This heat radiation includes heat radiation by the air flow from the cooling plates 115 and 116 and heat radiation by radiation. The heat radiation by the air flow is performed not only from the inner surface (surface on the light emitting unit substrate 113 side) of the cooling plates 115 and 116 but also from the outer surface (surface opposite to the light emitting unit substrate 113). The inner surfaces of the cooling plates 115, 116 can efficiently dissipate heat because the air flow rate becomes faster as they approach the light emitting unit 112.

  Heat radiation by radiation is performed not only from the inner surfaces of the cooling plates 115 and 116 but also from the outer surfaces. Since the outer surfaces of the cooling plates 115 and 116 can diffuse heat to a surrounding area over a wide area, efficient heat dissipation can be realized. On the other hand, the inner surfaces of the cooling plates 115 and 116 are curved so as to incline toward the outer side as they move away from the light emitting unit 112 in the reciprocating direction S. It will be emitted smoothly.

  As described above, when reading an image using the document table 160, the image forming apparatus 1 effectively uses the pair of cooling plates 115 and 116 by using the reciprocating motion of the light source unit 110 in scanning. And can dissipate heat.

  FIG. 3 is a schematic configuration diagram illustrating a state in which image reading is performed using the ADF 30 in the image forming apparatus 1 according to the embodiment. FIG. 3A is a schematic configuration diagram of the image forming apparatus 1. FIG. 3B is a perspective view showing the cooling unit 150. When an automatic document feeder (ADF) 30 that automatically conveys a document is used, the first carriage 120 and the second carriage 137 are fixed at a preset sub-scanning position to automatically feed the document. The scanning is performed.

  The ADF 30 includes a paper feed roller 31 and a document reading slit 32. The paper feed roller 31 automatically feeds the document and reads the document through the document reading slit 32. In this case, since the first carriage 120 is fixed at a preset sub-scanning position, the light source unit 110 mounted on the first carriage 120 is also fixed at a predetermined position.

  The cooling unit 150 includes a cooling fan 151 and a cylindrical part 152 attached to the cooling fan 151. The cylindrical portion 152 is hollow inside and has a linear slit 153 at one place. The slit 153 faces the end portion of the pair of cooling plates 115 and 116 on the side having the first end portion interval Ce1 and can blow out air in the reciprocating direction of the light source unit 110. Since the pair of cooling plates 115 and 116 have a shape in which the interval increases from the light emitting unit 112 side toward the slit 153, the air from the slit 153 can be taken in effectively. Thereby, the air having a flow velocity increased by the shape of the pair of cooling plates 115 and 116 can effectively take heat from the light emitting unit 112 and the copper layer 114. The cooling unit 150 is also called a blower unit.

  A part of the driving force is branched and mechanically supplied to the cooling fan 151 from a driving force transmission path from a motor (not shown) installed in the image forming apparatus 1 to the paper feed roller 31 of the ADF 30. Has been. The paper feed roller 31 is driven only when an image is read using the ADF 30. Therefore, the cooling fan 151 is driven and blown only when an image is read using the ADF 30. Accordingly, the cooling fan 151 is driven only when the light source unit 110 is fixed adjacent to the slit 153. As a result, the cooling fan 151 is reliably driven only when necessary without performing a special control operation.

  As described above, when the image forming apparatus 1 according to the present embodiment reads an image using the document table 160, the reciprocating motion of the light source unit 110 in scanning is used, and the pair of cooling plates 115 and 116. Can be used effectively to dissipate heat. On the other hand, when image reading is performed using the ADF 30, the cooling fan 151 driven only in this case is driven only when the light source unit 110 is fixed adjacent to the slit 153. become. Thereby, heat can be effectively radiated by the shape of the pair of cooling plates 115 and 116.

  The present invention can be implemented not only in the above embodiment but also in the following modifications.

  Modification 1: Although the said embodiment uses the heat sink made from an aluminum alloy, you may make it use another material. Further, the heat radiating plate may be applied with, for example, a heat radiation sheet or a heat shielding paint that reflects radiant heat. Specifically, as shown in FIG. 4, heat radiation sheets P <b> 1 and P <b> 6 (exaggerated as thick line portions) are attached on the outside of the heat radiating plate, so that heat can be efficiently radiated by heat radiation. . On the other hand, when the heat radiation sheets P2 to P5 (shown exaggerated as thick line portions) are attached to regions and angles that do not face the light emitting portion 112 and the copper layer 114 on the inner side of the heat sink, both ends from the center of the heat sink It is possible to dissipate heat by heat radiation at both ends. Thereby, it is possible to effectively radiate heat while suppressing heat radiation in the reverse direction from the heat radiating plate to the light emitting unit 112.

  Modification 2: The above embodiment employs a configuration in which a document can be read regardless of whether the document table or the ADF is used, but may be applied to a configuration dedicated to reading on the document table. It can also be applied to a configuration dedicated to reading by ADF. When adopting a configuration dedicated to reading by ADF, the cooling fans 151 are arranged on the left and right sides of the light emitting unit substrate 113 without using the cylindrical portion 152, and the configuration of the pair of cooling plates 115 and 116 is also main. The shape may be changed to allow the wind to flow smoothly in the scanning direction. Further, the control unit 10 may drive the cooling fan 151 by idling as required (for example, during abnormal overheating) even if no document is placed on the ADF.

  Modification 3: In the above embodiment, the pair of cooling plates 115 and 116 are disposed opposite to each other across the light emitting unit substrate 113 in a direction perpendicular to the reciprocating direction S of the light source unit 110 and the main scanning direction. However, it is not always necessary to be vertical, and it is only necessary that the light emitting unit substrate 113 is disposed opposite to the surface in the direction intersecting the reciprocating direction S. However, if the direction is vertical, a smooth wind flow can be realized when the light source unit 110 reciprocates.

  Modification 4: In the above embodiment, the light emitting unit substrate is embedded with a copper layer that is thermally coupled to the light emitting unit and functions as a heat sink, but is not limited to the copper layer, and has a thermal conductivity. Other high materials (such as metal layers) may be used. Further, the light emitting unit is not limited to the light emitting diode (LED), and may be another light source.

  Modification 5: In the above-described embodiment, the cooling plate has a hyperbolic shape (or arc shape), but may have another shape as long as the light emitting portion interval is smaller than any of both end portion intervals. For example, it may be a mountain shape formed from a bent straight line. However, it is preferable that the cooling plate is formed so that the interval continuously increases from the light emitting portion interval toward the both end portion interval.

  Modification 6: In the above-described embodiment, the present invention is applied to the image forming apparatus. However, the present invention can also be applied to a dedicated scanner or other image reading apparatus or an illumination device used for the image reading apparatus.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Control part 20 Image forming part 30 Automatic document feeder (ADF)
31 Paper feed roller 32 Document reading slit 40 Storage unit 100 Image reading unit 110 Light source unit 112 Light emitting unit 113 Light emitting unit substrate 114 Copper layers 115 and 116 Cooling plate 120 First carriage 131 First reflecting mirror 135 Second reflecting mirror 136 Third Reflective mirror 137 Second carriage 138 Condensing lens 141 Image sensor 150 Cooling unit 151 Cooling fan 152 Cylindrical unit 153 Slit 160 Document table Ce1 First end interval Ce2 Second end interval Cm Light emitting unit interval

Claims (5)

An illumination device used in an image reading device that reads an image on a document by reciprocating,
A light emitting unit that emits light to the original;
A light emitting unit substrate having a metal layer arranged in the main scanning direction, extending in the reciprocating direction, and thermally coupled to the light emitting unit;
A pair of cooling plates disposed opposite to each other across the light emitting unit substrate in a direction intersecting the reciprocating direction which is the reciprocating direction and the main scanning direction;
A heat radiation sheet affixed to the outer side of the pair of cooling plates; and a heat radiation sheet affixed to a region not facing the light emitting portion and the metal layer on the inner side of the pair of cooling plates. ,
The pair of cooling plates has an interval between the pair of cooling plates at a position where the light emitting unit is disposed in the reciprocating direction as a light emitting unit interval, and both ends of the pair of cooling plates in the reciprocating direction. A lighting device in which the interval between the light emitting portions is smaller than any of the intervals between the both end portions. An image reading device,
An illumination device according to claim 1 Symbol placement,
A scanning mechanism for reciprocating the illumination device;
An image reading apparatus comprising: an image signal generation unit that receives reflected light from the document and generates an image signal. The image reading apparatus according to claim 2 , further comprising:
An automatic document feeder that automatically conveys the document;
A blower unit that is driven by branching a part of the driving force transmitted to the automatic document feeder;
A control unit for controlling the scanning mechanism and the blower unit,
In the case where the control unit reads an image using the automatic document feeder, the illuminating device is arranged at a predetermined position set in advance for reading an image of the document conveyed by the automatic document feeder. And
The image reading device that blows air toward the pair of cooling plates of the illumination device arranged at the predetermined position. The image reading apparatus according to claim 3,
The air blowing part includes a cooling fan and a cylindrical part that is attached to the cooling fan, has a cavity inside, and has a linear slit,
The slit is an image reading apparatus configured to face the pair of cooling plates and blow out air in a reciprocating direction of the light emitting unit . An image forming apparatus,
An image reading apparatus according to any one of claims 2 to 4 ,
An image forming apparatus comprising: an image forming unit that forms an image on a print medium based on the image signal generating unit.