JP4794950B2 - COOLING DEVICE, IMAGE READING DEVICE AND IMAGE FORMING DEVICE HAVING THE SAME - Google Patents

Description

  The present invention relates to a cooling apparatus that cools an object to be cooled by applying an air current, and an image reading apparatus and an image forming apparatus provided with the cooling apparatus.

  In an image forming apparatus having an image reading unit such as an image scanner or an image reading unit such as a copying machine or a facsimile, light from a light source unit is irradiated onto an original (image reading object) and reflected light from the original Some of them are provided with image forming means (light receiving unit and photoelectric conversion unit) for forming an image on a CCD (Charge Coupled Devices) or the like with a lens. In recent years, in order to meet demands for higher image reading speed and smaller apparatus, a drive circuit unit for driving a photoelectric conversion unit such as a CCD, a signal processing circuit unit for processing an electric signal obtained by the photoelectric conversion unit, etc. Circuit board with high density, faster drive clock of the circuit element, higher integration of integrated circuits mounted on the circuit board, etc., temperature rise of the circuit element has become a problem Yes.

  In order to solve this problem, Patent Document 1 covers the drive circuit unit and the signal processing circuit unit as a method of cooling the drive circuit unit and the signal processing circuit unit including the circuit elements that are the objects to be cooled. A cooling device is disclosed that is housed inside and that feeds outside air into the cover by a cooling fan. This cooling device is provided with an opening for taking the airflow from the cooling fan into the cover and a discharge opening for letting the air in the cover escape. As a result, the outside air sent into the cover by the cooling fan hits the drive circuit section and the signal processing circuit section in the cover and takes away the heat of the circuit elements, and the warmed air is discharged from the discharge opening to the outside of the cover. The Since this cooling device employs an air cooling system that cools circuit elements by the flow of air, there is an advantage that the configuration is simpler than other known cooling mechanisms (such as a water cooling system). In addition, according to the description in Patent Document 1, since both the drive circuit unit and the signal processing circuit unit including the circuit element that is the object to be cooled are accommodated in the same cover, the image reading apparatus should be cooled. The cooling target can be cooled efficiently.

JP 2004-246134 A

  However, in the cooling device described in Patent Document 1, no effort has been made to efficiently exhaust the warm air in the cover by simply sending outside air into the cover by a cooling fan. Therefore, most of the airflow in the cover generated by the cooling fan only convects in the cover, and the air in the cover is not efficiently replaced. As a result, no matter how much the flow velocity of the air flow by the cooling fan is increased, the cooling effect cannot be improved only by the warm air in the cover hitting the circuit element.

  In the above description, the case where the circuit element of the image reading apparatus is a cooling object is taken as an example. However, in any apparatus having a cooling object such as a circuit element where heat generation is a problem, the cooling object It is an important issue to cool the battery with an efficient and simple configuration.

  The present invention has been made in view of the above background, and an object of the present invention is to provide a cooling device capable of enhancing a cooling effect by an air cooling system having a relatively simple configuration, and an image reading device including the same. An apparatus and an image forming apparatus are provided.

In order to achieve the above object, the invention of claim 1 includes a first air flow generating means for generating a first air flow that hits the object to be cooled, and a second air different from the object to be cooled without hitting the object to be cooled. and a second air flow generating means for generating the second air flow strikes the cooling object, and a first air stream after the second air flow generating means strikes the second stream with said first cooling object that caused In addition to being configured to merge with each other, the flow velocity of the second air flow is higher than the flow velocity of the first air flow at the merge point.
According to a second aspect of the present invention, in the cooling device of the first aspect, the first airflow generation means and the second airflow generation means are configured as a common airflow generation means, and the common airflow generation means generates the common airflow generation means. An airflow dividing means for dividing the airflow into the first airflow and the second airflow is provided.
According to a third aspect of the present invention, in the cooling device of the first aspect, the first airflow generation means and the second airflow generation means are configured as individual airflow generation means, and the first airflow generation means is the cooling device. It arrange | positions in the vicinity of a target object, It is characterized by the above-mentioned.
According to a fourth aspect of the present invention, in the cooling device of the third aspect, the apparatus has a case for accommodating the object to be cooled therein, and the first air flow generated by the first air flow generating means is sent to the outside of the case. A discharge opening for discharging is provided in the case, and the second air flow generating means is configured so that the second air flow flows in the vicinity of the outlet side of the discharge opening along the outer surface of the case. The second airflow and the first airflow discharged from the discharge opening are configured to merge with each other.
The invention of claim 5 is the cooling device of claim 4, further comprising a plate-like member on which the object to be cooled is mounted, and in a normal direction of a surface of the plate-like member on which the object to be cooled is mounted. On the other hand, the first air flow generating means is configured such that the first air flow hits the object to be cooled from a direction inclined to the side opposite to the discharge opening.
According to a sixth aspect of the present invention, in the cooling device according to the fourth or fifth aspect, the first air flow generation means is configured such that a part of the first air flow is directly discharged from the discharge opening. It is what.
According to a seventh aspect of the present invention, in the cooling device according to the fourth, fifth, or sixth aspect, the case is provided with a suction opening for sucking outside air.
The invention of claim 8 is characterized in that, in the cooling device of claim 4, 5, 6 or 7, a metal case is used as the case.
The invention of claim 9 is the cooling device of claim 4, 5, 6, 7 or 8, wherein the surface of the case facing the flow direction of the second airflow generated by the second airflow generating means is The discharge opening is inclined toward the vicinity of the outlet side.
According to a tenth aspect of the present invention, there is provided a light source unit that irradiates light to an image reading object, a light receiving unit that receives reflected light reflected by the image reading object, and an image based on light received by the light receiving unit. An image reading device having an image information generation unit for generating information, comprising the cooling device according to claim 1, 2, 3, 4, 5, 6, 7, 8, or 9. The cooling device includes the image reading device. It is characterized in that at least one component among the components constituting the apparatus is cooled as the cooling object.
According to an eleventh aspect of the present invention, in the image reading device according to the tenth aspect, the image information generation unit includes a photoelectric conversion unit that photoelectrically converts light received by the light receiving unit, and a drive circuit that drives the photoelectric conversion unit. And a signal processing circuit unit that processes an electrical signal obtained by the photoelectric conversion unit, and the at least one component as the cooling object includes the drive circuit unit and the signal processing circuit unit It is characterized by being at least one of these.
According to a twelfth aspect of the present invention, there is provided an image forming apparatus comprising: an image reading unit; and an image forming unit that forms an image on a recording material based on image information read by the image reading unit. The image reading apparatus according to claim 10 or 11 is used.
According to a thirteenth aspect of the present invention, in the image forming apparatus for forming an image on a recording material based on image information, the cooling device according to the first, second, third, fourth, fifth, sixth, seventh, eighth or ninth aspect is provided. And the cooling device cools at least one of the components constituting the image forming apparatus as the cooling object.

  According to the present invention, after the first airflow that hits the object to be cooled hits the object to be cooled, it merges with the second airflow that does not hit the object to be cooled. Since the flow velocity of the second airflow is faster than the flow velocity of the first airflow at this confluence, the gas of the first airflow that has warmed up against the object to be cooled is drawn into the second airflow side by the Venturi effect and rides on the second airflow. Moving. As a result, it is possible to efficiently remove the gas of the first air stream that has been warmed by hitting the object to be cooled from the surrounding space of the object to be cooled. Thereby, the new gas (cooled gas before hitting a cooling target object) riding on the first air flow can be efficiently taken into the surrounding space of the cooling target object.

  As mentioned above, according to this invention, in the air cooling system which is a comparatively simple structure, the new gas (cooled gas before hitting a cooling target object) which got on the 1st air current with respect to the surrounding space of the cooling target object is shown. Since it can take in efficiently, the outstanding effect that the cooling effect with respect to the cooling target object can be heightened is show | played.

Hereinafter, an embodiment in which the present invention is applied to a copying machine which is a digital image forming apparatus including an image reading apparatus will be described.
FIG. 2 is a schematic configuration diagram showing the entire copying machine of the present embodiment.
The copier 1 of this embodiment is roughly divided into an image reading unit (image reading device) A, an image processing unit B, an image storage unit C, an image writing unit D, an image recording unit E, a paper feeding unit F, and the like. It is configured. In the present embodiment, the image writing unit D and the image recording unit E constitute an image forming unit. In the image reading unit A, a document d, which is an image reading object placed on a platen glass (platen glass) 11, is supplied by a xenon lamp (light source unit) 12 provided on a carriage that moves on a guide rail 18. Illuminated. The reflected light from the document d is reflected by the first mirror 13, the second mirror 14, and the third mirror 15, passes through the imaging lens 16, and is line-shaped optically by the CCD image sensor 17 as a light receiving unit and a photoelectric conversion unit. Images are sequentially photoelectrically converted into electrical signals. As an example, the CCD image sensor 17 has a configuration of about 5000 pixels, the size of one pixel is 7 [μm], and the reading unit of one pixel on the document is 63.5 [μm].

  The analog signal (electrical signal) photoelectrically converted by the CCD image sensor 17 is subjected to analog signal processing in the image processing unit B and then A / D converted. The digital signal is subjected to predetermined digital signal processing in the image processing unit B, and image data that is image information based on the digital signal after the processing is temporarily stored in the image storage unit C. Digital signal processing performed by the image processing unit B includes, for example, shading correction, luminance / density conversion, EE processing, character / halftone discrimination, filter / magnification processing, copy gamma correction, writing density correction, two beam control, Examples include error diffusion processing and data compression processing. The image data temporarily stored in the image storage unit C is output to the image writing unit D. The image writing unit D outputs writing light based on the image data from the semiconductor laser. The writing light from the semiconductor laser is rotationally scanned by a rotary polygon mirror (polygon mirror) 22 rotated by a drive motor 21, passes through an fθ lens 23, a first mirror 24, a second mirror 25, a cylindrical lens 26, The light passes through the third mirror 27, is emitted from the cover glass 28, and is irradiated onto a photosensitive drum 31 as a latent image carrier provided in the image recording unit E.

The image recording unit E includes a photosensitive drum 31, and a charger 32, a developing unit 33, a transfer unit 34, a separator 35, a cleaning device 36, and the like disposed around the photosensitive drum 31. Further, a transport unit 37, a fixing unit 38, and a paper discharge unit 39 are also arranged on the downstream side of the separator 35, and these also constitute an image recording unit E.
The paper feed unit F includes a paper feed cassette 41 that accommodates transfer paper P as a recording material, a paper feed mechanism 42 that separates and feeds the transfer paper P in the paper feed cassette 41, and the like.

FIG. 3 is an explanatory diagram showing a schematic configuration of the image reading unit A.
A drive shaft 101 is rotatably supported in the unit casing 10 of the image reading unit A. The timing pulley 102 is fixed to one shaft end of the drive shaft 101, and the drive shaft 101 is rotated via the timing belt 104 by the drive rotation of the timing pulley 103 attached to the drive shaft of the drive motor M. . Drive pulleys 105 are fixed in the vicinity of both shaft ends of the drive shaft 101. One end of the flexible wire 106 wound a plurality of times is locked to each drive pulley 105. The flexible wire 106 is stretched between idle pulleys 107A, 107B, and 107C, and the other end is locked to the wire stopper 108. The drive pulley 105, the flexible wire 106, the idle pulleys 107A, 107B, 107C, and the wire stopper 108 are a set on the back side (the back side in FIG. 2) of the image reading unit A where the drive motor M is installed. A set of flexible wires 106 are arranged on the side (the front side in FIG. 2) such that the flexible wires 106 are parallel to each other.

  The end surfaces on the back side and the front side of the exposure mirror unit 110 on which the xenon lamp 12 and the first mirror 13 are mounted are locked at predetermined positions of the flexible wire 106 by the front and rear mounting tools 111, respectively. On the other hand, end surfaces on the back side and the front side of the V mirror unit 120 on which the second mirror 14 and the third mirror 15 are mounted are respectively integrated with the front and rear support members 121. These support members 121 rotatably support the movable pulley 122, and the flexible wire 106 is wound around the movable pulley 122. When the drive pulley 105 is rotationally driven by the drive motor M, the flexible wire 106 is driven, the exposure mirror unit 110 moves at a predetermined speed v, and the V mirror unit 120 including the moving pulley 122 moves at a speed v / 2. Moving. The exposure mirror unit 110 and the V mirror unit 120 slide on the surface of the guide rail 18 and reciprocate in the sub-scanning direction. The exposure mirror unit 110 starts moving from the initial position S1 when moving forward (when moving in the scanning direction), and performs image exposure, and when returning (when moving in the scanning back direction), image exposure ends. Later, a quick return is made to return to the initial position S1.

FIG. 4 is a cross-sectional view of the exposure mirror unit 110 at the initial position.
FIG. 5 is a schematic diagram when the exposure mirror unit 110 is viewed from the scanning direction side.
A sliding member 114 is fixed to the bottom of the exposure mirror unit 110. The sliding member 114 slides on the guide rail 18 and moves. The exposure mirror unit 110 slides on the guide rail 18 and starts scanning exposure in the scanning direction from the initial position S1 near the home position or near the home position. Move to. An elastic body 19 is installed on the upper surface of the guide rail 18 near the initial position S1 where the exposure mirror unit 110 starts scanning exposure. As the elastic body 19, foamed polyurethane or the like can be used. Further, in order to improve the durability life of repeated scanning, a film is stuck on the elastic body 19. PET or the like can be used as the film material. Since the exposure mirror unit 110 quickly returns at the time of backward movement, the exposure mirror unit 110 moves at high speed toward the initial position S1, and suddenly stops at the initial position S1. At the time of this sudden stop, the exposure mirror unit 110 vibrates, but the bottom surface of the exposure mirror unit 110 and the elastic body 19 provided on the upper surface in the vicinity of the initial position S1 of the guide rail 18 come into contact with each other. The vibration is quickly damped. Therefore, it is possible to reduce the residual vibration at the time of the previous scan-back when the exposure mirror unit 110 scans after the second continuous copy.

FIG. 6 is a cross-sectional view of the V mirror unit 120 at the initial position.
FIG. 7 is a schematic diagram when the V mirror unit 120 is viewed from the scanning direction.
Similarly to the exposure mirror unit 110, a sliding member 124 is fixed to the bottom of the V mirror unit 120 as well. The sliding member 124 is also slidable on the guide rail 18 and can move. An elastic body 20 is disposed on the upper surface of the guide rail 18 between the initial position O1 of the V mirror unit 120 and the reading start position O2. Similar to the case of the exposure mirror unit 110, the elastic body 20 is also for reducing the residual vibration at the time of the previous scan-back when the V mirror unit 120 scans after the second continuous copy.

FIG. 8 is a functional block diagram of an electric circuit provided in the image reading unit A.
As described above, an optical signal (reflected light from the document d) received by the CCD image sensor 17 constituting the light receiving unit and the photoelectric conversion unit is photoelectrically converted by the photoelectric conversion element 211 which is a CCD in the CCD image sensor 17. And converted into an analog signal which is an electric signal. This analog signal is input to an analog signal processing unit 213 as a signal processing circuit unit. At this time, the emitter follower 212 performs impedance conversion in order to improve the sampling accuracy in the analog signal processing unit 213. The analog signal processing unit samples the input analog signal, performs preprocessing for A / D conversion, and outputs the processed analog signal to the A / D converter 214. The A / D converter 214 converts the input analog signal into a digital signal and outputs the digital signal to the image processing unit B. The timing generation ASIC 215 generates a driving clock for the photoelectric conversion element 211, a timing signal for the analog signal processing unit 213 and the A / D converter 214, and performs register control for the analog signal processing unit 213. That is, the timing generation ASIC 215 functions as a drive circuit unit that drives the CCD of the CCD image sensor 17 that is a photoelectric conversion unit.

  In such an electric circuit in the image reading unit A, the clock generated by the timing generation ASIC 215 is increased in response to the recent demand for higher image reading speed, and the timing signal of the analog signal processing unit 213 is also generated. High clock. For this reason, the problem of heat generation in the timing generation ASIC 215 and the analog signal processing unit 213 has become apparent, and a cooling system that can be sufficiently cooled is required to stably operate these components. In order to meet the recent demand for downsizing of the image reading unit A, this heat generation problem is caused by increasing the density of circuit elements on the circuit board on which the timing generation ASIC 215 and the analog signal processing unit 213 are mounted, and the timing generation ASIC 215 and analog As the integrated circuit constituting the signal processing unit 213 is highly integrated, it becomes more serious. Therefore, the development of a cooling system with a high cooling effect is an urgent task. Moreover, in order to meet the recent demand for downsizing of the image reading unit A, it is necessary to sufficiently cool the timing generation ASIC 215 and the analog signal processing unit 213 in which heat generation is a problem with an air cooling system having a relatively simple configuration. desired.

FIG. 9 is an explanatory diagram illustrating a schematic configuration of a cooling device provided in the image reading unit A. FIG. 8 shows the image reading unit A as viewed from the back side.
FIG. 10 is an explanatory diagram illustrating a schematic configuration of the cooling device when the image reading unit A is viewed from above.
In this embodiment, circuit elements in the image reading unit A such as the timing generation ASIC 215 and the analog signal processing unit 213 are mounted on a single circuit board 210 as a plate-like member. A CCD image sensor 17 is also mounted on the circuit board 210. The CCD image sensor 17 is mounted on the surface of the circuit board 210. On the other hand, among the circuit elements on the circuit board 210, at least the circuit elements having a problem of heat generation such as the timing generation ASIC 215 and the analog signal processing unit 213 are mounted on the back surface of the circuit board 210. The circuit board 210 is installed so that the board surface thereof is substantially parallel to the vertical plane, and is housed in the metal case 201 together with the imaging lens 16. Thereby, radiation noise from the circuit board 210 that operates at a high clock is shielded, and malfunctions such as malfunction of circuit components provided outside the metal case 201 due to the radiation noise are prevented. Between the metal case 201 and the right side surface of the unit casing 10 in the figure, a power circuit board 216 mounted with a power circuit for supplying power to the circuit board 210 and various fans described later is disposed. . The power supply circuit board 216 also generates heat and needs to be cooled.

  As shown in FIGS. 9 and 10, the unit casing 10 of the image reading unit A is provided with an intake opening 10a on the right side surface in the figure, and as shown in FIG. An exhaust opening 10b is provided in the left region. An intake fan 202 is attached to the intake opening 10a, and an exhaust fan 203 is attached to the exhaust opening 10b. These fans 202 and 203 function as second air flow generation means, and generate a second air flow that flows in the unit casing 10 from the intake opening 10a toward the exhaust opening 10b. Specifically, the second airflow passes through the power supply circuit board 216 from the intake opening 10a, passes through the upper portion of the metal case 201, and flows from the exhaust opening 10b to the outside of the unit casing 10. When the second airflow passes through the power supply circuit board 216, the power supply circuit board 216 is cooled by removing heat generated in the power supply circuit board 216.

FIG. 11 is an explanatory diagram when the metal case 201 is viewed obliquely from above. Note that the front side of the metal case 201 in the drawing shows a partially broken state.
A suction opening 201a is provided on the right side surface in FIG. 9 of the metal case 201 (the right side surface in FIG. 11). A discharge opening 201 b is provided on the upper surface of the metal case 201. As shown in FIG. 11, the discharge opening 201 b is provided over a predetermined range on the right side in the drawing from a position facing the upper end of the circuit board 210 on the upper surface of the metal case 201. Note that the position of the discharge opening 201b is slightly displaced in the direction away from the back surface of the circuit board from directly above the position where the timing generation ASIC 215 and the analog signal processing unit 213 are mounted on the back surface of the circuit board 210. Is desirable.

In the metal case 201, an internal fan 204 is provided as a first airflow generating means for generating a first airflow that hits circuit elements such as the timing generation ASIC 215 and the analog signal processing unit 213 mounted on the back surface of the circuit board 210. It has been. The internal fan 204 is arranged so that the first airflow strikes the back surface of the circuit board 210 standing substantially vertically from obliquely below. That is, from the direction (in the present embodiment, obliquely downward) the first airflow is inclined to the side opposite to the discharge opening 201b with respect to the normal direction of the back surface of the circuit board 210 (the horizontal direction in the present embodiment). The internal fan 204 is arranged so as to hit the circuit elements such as the timing generation ASIC 215 and the analog signal processing unit 213 mounted on the circuit.
Since the air flow generated by the internal fan 204 is faster in the outer peripheral portion than in the central portion of the internal fan 204, the suction opening 201a and the discharge opening 201b of the metal case 201 are respectively shown in FIG. , Provided at a location corresponding to the outer peripheral portion of the internal fan 204.

Next, the flow of the airflow in the unit casing 10 in this embodiment will be described.
FIG. 1 is an explanatory diagram showing the flow of airflow in the unit casing 10. FIG. 1 shows the unit casing 10 as viewed from the back side.
The air sucked into the unit casing 10 from the intake opening 10 a by the second airflow Y generated by the intake fan 202 rides on the second airflow Y, passes through the power circuit board 216, and moves to the upper part of the metal case 201. It flows toward. At this time, part of the second airflow Y that has passed through the power circuit board 216 rides on the first airflow X and flows into the metal case 201 from the suction opening 201a. The first airflow X is mainly generated by the suction force of the internal fan 204 provided in the metal case 201, but it is considered that there is a considerable influence by the intake fan 202. The air that has flowed into the metal case 201 is applied to the back surface of the circuit board 210 that is standing substantially vertically from below by the first airflow X generated by the internal fan 204. In this way, the first airflow X hits a circuit element (an object to be cooled) such as the timing generation ASIC 215 or the analog signal processing unit 213 mounted on the back surface of the circuit board 210, thereby depriving the circuit element of heat. The air that has been deprived of heat from the circuit elements rides on the first airflow X and is discharged to the outside of the metal case 201 through the discharge opening 201b provided on the upper surface of the metal case 201.

  Here, in this embodiment, the 1st airflow X which flowed out from the discharge opening part 201b merges with the 2nd airflow Y which flows along the upper surface of the metal case 201 in the exit side vicinity of the discharge opening part 201b. At this confluence point, the flow velocity of the second airflow Y is faster than the flow velocity of the first airflow X. Therefore, the air of the first airflow X warmed by removing heat from the circuit elements on the back surface of the circuit board 210 is drawn to the second airflow Y side by the venturi effect. That is, the warm air in the metal case 201 is efficiently discharged from the discharge opening 201b by the venturi effect between the first airflow X and the second airflow Y. As a result, the warm air in the metal case 201 is efficiently removed from the surrounding space on the back surface of the circuit board 210, and new air can be efficiently taken into the surrounding space from the suction opening 201a of the metal case 201. it can. In the surrounding space on the back surface of the circuit board 210 inside the metal case 201, such an air flow is generated. As a result, air does not stay in the surrounding space, and the cooling effect is enhanced.

  In particular, in the present embodiment, the direction in which the first airflow is inclined to the side opposite to the discharge opening 201b with respect to the normal direction (the horizontal direction in the present embodiment) of the back surface of the circuit board 210 (in the present embodiment, obliquely downward) ), It is configured so as to hit the circuit elements such as the timing generation ASIC 215 and the analog signal processing unit 213 mounted on the back surface thereof, and thereby the effect of more efficiently discharging the air in the metal case 201 from the discharge opening 201b. can get.

  This point will be described in detail. In the present embodiment, the first airflow X sent out from the internal fan 204 strikes the back surface of the circuit board 210 obliquely from below (about 45 [°]). Therefore, the first airflow X hitting the back surface of the circuit board 210 can smoothly change the direction of the flow to a direction parallel to the back surface of the circuit board 210, and upward along the back surface of the circuit board 210. It will flow. And in this embodiment, since the discharge opening part 201b is provided in the upper surface part of the metal case 201 which the 1st airflow X goes to, the 1st airflow which goes upward along the back surface of the circuit board 210 is provided. X can flow out of the discharge opening 201b as it is. With such a configuration, in the present embodiment, the first airflow X sent out from the internal fan 204 is suppressed from reducing the deceleration of the first airflow less than the configuration in which the first airflow X is applied to the back surface of the circuit board 210 from the normal direction. Therefore, the effect that the air in the metal case 201 is discharged from the discharge opening 201b more efficiently can be obtained.

  According to an experiment conducted by the present inventor, the normal line relative to the back surface of the circuit board 210 is compared with the configuration in which the first airflow X is applied from the internal fan 204 to the back surface of the circuit board 210 from the normal direction. The configuration applied obliquely from below 45 [°] with respect to the direction can lower the ambient temperature of the timing generation ASIC 215 and the analog signal processing unit 213 mounted on the back surface of the circuit board 210 by 5 [° C] or more. It was.

  In order to exhaust the air in the metal case 201 from the discharge opening 201b more efficiently, a part of the first airflow X sent from the internal fan 204 is directly discharged from the discharge opening 201b. Also good. In this case, the flow velocity of the other part of the first airflow X, that is, the part that hits the back surface of the circuit board 210 is slower than the part of the first airflow X that is directly discharged from the discharge opening 201b. As a result, the other part of the first airflow X that hits the back surface of the circuit board 210 and flows upward along the back surface of the first airflow X near the inlet side of the discharge opening 201b is faster than this. Join the department. Therefore, at this junction, the air in the other part of the first airflow X that has been warmed by hitting the back surface of the circuit board 210 is drawn into a part of the first airflow X due to the venturi effect. Thereby, compared with the configuration in which all of the first airflow X hits the back surface of the circuit board 210, the flow velocity of the other part of the first airflow X passing through the surrounding space on the back surface of the circuit board 210 can be increased. It becomes possible to more efficiently remove the warm air from the surrounding space on the back surface.

  Of course, the present invention is not limited to the configuration in which the first airflow X is applied to the back surface of the circuit board 210 from obliquely below as described above. There may be.

  In the present embodiment, a part of the second airflow Y generated by the intake fan 202 collides with the surface of the metal case 201 where the intake opening 201a is provided. Due to this collision, the flow velocity of the second airflow Y flowing along the upper surface of the metal case 201 becomes slow, and there is a possibility that a high venturi effect cannot be obtained in the vicinity of the outlet side of the discharge opening 201b. Therefore, in the present embodiment, a chamfered corner portion located at the upper portion of the surface on which the suction opening 201a of the metal case 201 is provided, and an inclined surface 201c that is inclined toward the vicinity of the outlet side of the discharge opening 201b is provided. Yes. Thereby, the flow direction of the 2nd airflow Y which collided with the inclined surface 201c can be smoothly changed to the upper surface of the metal case 201 provided with the discharge opening 201b, and the exit side vicinity of the discharge opening 201b It can suppress that the flow velocity of the 2nd airflow Y which flows toward is slowed down.

According to the airflow visualization experiment conducted by the present inventor, in the configuration in which the inclined surface 201c is not formed (not chamfered), the second airflow that collides with the surface of the metal case 201 provided with the suction opening 201a becomes a vortex. In contrast to the stagnation, in the configuration of the present embodiment in which the inclined surface 201c is formed, such a vortex is eliminated.
Note that the entire surface of the metal case 201 (the surface provided with the suction opening 201a) facing the flow direction of the second airflow Y may be inclined toward the vicinity of the outlet side of the discharge opening 201b. However, in this case, it is necessary to consider that the air flow to the suction opening 201a of the metal case 201 may be deteriorated.

  In the present embodiment, the edge of the circuit board 210 and the inner wall of the metal case 201 are arranged close to each other with a slight gap, and the internal space of the metal case 201 is partitioned by the circuit board 210. It has become. Thus, the first airflow X generated by the internal fan 204 is prevented from passing to the surface side of the circuit board 210 through between the edge of the circuit board 210 and the inner wall of the metal case 201. . When the first airflow X flows to the surface side of the circuit board 210, foreign matters such as dust that are carried on the first airflow X may adhere to the sensor surface of the CCD image sensor 17. According to the present embodiment, it is possible to suppress foreign matter from adhering to the sensor surface of the CCD image sensor 17.

[Modification]
Next, a modification of the cooling device in the above embodiment will be described.
FIG. 12 is an explanatory diagram when the metal case in the cooling device of the present modification is viewed obliquely from above.
FIG. 13 is an explanatory view showing the flow of airflow in the unit casing 10 in this modification. FIG. 13 shows the unit casing 10 as viewed from the back side.
In this modification, the internal fan 204 in the above embodiment is omitted, and the first airflow X and the second airflow Y are generated by separating the airflow flowing into the unit casing 10 by the intake fan 202 into two. Is adopted. In other words, in the present modification, the first airflow generation unit and the second airflow generation unit are configured by the intake fan 202 and the exhaust fan 203 which are common airflow generation units.

  The airflow Z generated by the intake fan 202 is moved by the metal case 301 along the upper surface of the metal case 301, and the first airflow entering the inside of the metal case from the suction opening 301 a of the metal case 301. And X. The first airflow X into the metal case 201 hits the back surface of the circuit board 210 standing substantially vertically from the normal direction. For this reason, the flow of the first airflow X that hits the back surface of the circuit board 210 is greatly decelerated, but part of it flows out of the discharge opening 301 b provided on the upper surface of the metal case 301. Here, in the present modification, the first airflow X flowing out from the discharge opening 301 b merges with the second airflow Y flowing along the upper surface of the metal case 301 in the vicinity of the outlet side of the discharge opening 301 b. At this confluence point, the flow velocity of the second airflow Y is faster than the flow velocity of the first airflow X. Therefore, the air in the metal case 301 that has been heated by removing heat from the circuit elements on the back surface of the circuit board 210 is drawn into the second airflow Y side due to the venturi effect. As a result, the warm air in the metal case 201 is efficiently removed without staying in the surrounding space on the back surface of the circuit board 210. Therefore, new air flows from the suction opening 301a into the space around the back surface of the circuit board 210 inside the metal case 201, and the cooling effect is high.

According to this modification, since there is no internal fan 204, the cost can be reduced and the space can be saved as compared with the configuration of the above embodiment.
In the configuration of this modification, the flow velocity of the first airflow X flowing in the surrounding space on the back surface of the circuit board 210 is slower than the configuration of the above-described embodiment including the internal fan 204. The dimension of 301a and the discharge opening part 301b is enlarged compared with the said embodiment. In this case, since the effect of shielding the radiation noise generated in the circuit board 210 by the metal case cannot be sufficiently obtained, the configuration of this modification is compared with the advantages of cost reduction and space saving. It will be adopted at the discretion. If the problem of radiation noise is solved by another solution, the advantages of cost reduction and space saving can be enjoyed without any disadvantages.

As described above, the copying machine that is the image forming apparatus of the above-described embodiment (including the above-described modification) is provided on the image reading unit A and the transfer paper P that is a recording material based on the image information read by the image reading unit A. It has an image writing unit D and an image recording unit E as image forming units for forming images. The image reading unit A includes a xenon lamp 12 as a light source unit that emits light to an original d that is an image reading object, a light receiving unit that receives reflected light reflected from the original d, and a photoelectric conversion unit that photoelectrically converts the received light. As a photoelectric conversion element 211, a timing generation ASIC 215 as a drive circuit unit for driving the CCD, and an analog signal processing unit as a signal processing circuit unit for processing an analog signal which is an electrical signal obtained by the CCD 213 includes an image information generation unit. In addition, the image reading unit A is provided with a cooling device that cools at least the timing generation ASIC 215 and the circuit elements forming the analog signal processing unit 213 among the components constituting the image reading unit A as cooling objects. Yes. The cooling device includes an internal fan 204 serving as a first airflow generating unit that generates a first airflow X that hits a circuit element that is an object to be cooled, and a second airflow generating unit that generates a second airflow Y that does not hit the circuit element. As an intake fan 202 and an exhaust fan 203. The second airflow Y generated by the intake fan 202 and the exhaust fan 203 and the first airflow X after hitting the circuit element are merged with each other, and the first airflow X is formed at the junction. The flow rate of the second airflow Y is configured to be faster than the flow rate of. As a result, the gas (air) of the first airflow X warmed by hitting the circuit element that is the object to be cooled is drawn to the second airflow Y side by the venturi effect, and moves on the second airflow Y. As a result, it is possible to efficiently remove the air of the first airflow that has been warmed by hitting the circuit element from the space around the circuit element. Thereby, new gas (air before hitting the circuit element) riding on the first airflow X can be efficiently taken into the surrounding space of the circuit element. Therefore, an air cooling system having a high cooling effect can be realized.
Moreover, in the said modification, the 1st airflow generation means and the 2nd airflow generation means are comprised by the intake fan 202 and the exhaust fan 203 which are common airflow generation means, and the airflow which these fans 202 and 203 generate | occur | produced A metal case 301 is provided as airflow dividing means for dividing Z into a first airflow X and a second airflow Y. Thereby, compared with the case where a 1st airflow generation means and a 2nd airflow generation means are comprised by a separate airflow generation means, a number of parts can be decreased and cost reduction and space saving can be achieved.
On the other hand, in the above embodiment, the first airflow generating means and the second airflow generating means are configured as individual airflow generating means, and the internal fan 204 as the first airflow generating means is in the vicinity of the circuit element that is the object to be cooled. Is arranged. Thereby, since the 1st airflow X of a fast flow velocity can be applied with respect to a circuit element, a higher cooling effect can be acquired.
Moreover, in the said embodiment, in order to have the metal case 201 as a case which accommodates the circuit element which is a cooling target object inside, in order to discharge | emit the 1st airflow X which the internal fan 204 generate | occur | produced to the exterior of the metal case 201. The exhaust fan 201 and the exhaust fan 203 are configured so that the second airflow X flows in the vicinity of the outlet side of the discharge opening 201b along the outer surface (upper surface) of the metal case 201. Thus, the second airflow Y and the first airflow X discharged from the discharge opening 201b are configured to merge with each other. Thereby, the circuit element which is a cooling target object and the case exterior can be partitioned off. As a result, it is possible to suppress the warm air in the case from diffusing outside the case.
Moreover, in the said embodiment, it has the circuit board 210 as a plate-shaped member which mounted the circuit element which is a cooling target object, and with respect to the normal line direction of the surface (back surface) in which the circuit element of this circuit board 210 was mounted. Thus, the internal fan 204 is configured so that the first airflow X hits the circuit element from a direction inclined to the side opposite to the discharge opening 201b. Thereby, as above-mentioned, the air in the metal case 201 can be more efficiently discharged | emitted from the discharge opening part 201b, and a higher cooling effect is acquired. In particular, if the internal fan 204 is configured such that a part of the first airflow X is directly discharged from the discharge opening 201b, as described above, the air in the metal case 201 is more efficiently utilized using the Venturi effect. It can be discharged from the discharge opening 201b, and a higher cooling effect can be obtained.
Moreover, in the said embodiment, since the suction opening part 201a for suck | inhaling external air is provided in the metal case 201, new air can be efficiently taken in in the metal case 201, and a cooling effect can be improved more. .
Moreover, in the said embodiment, the metal case is used as a case which accommodates the circuit element which is a cooling target object inside. If the case is made of a metal having high thermal conductivity in this way, the heat inside the case is transferred to the case, and the second airflow flowing along the outer surface of the case takes the heat and can efficiently escape to the outside of the case. A higher cooling effect can be obtained. Moreover, in the said embodiment, since a cooling target object is a circuit element which emits radiation noise, the radiation noise can be shielded with a case by using a metal case as a case which accommodates this.
In the above embodiment, the surface of the metal case 201 facing the flow direction of the second airflow Y generated by the intake fan 202 and the exhaust fan 203 is inclined toward the vicinity of the outlet side of the discharge opening 201b. . Thereby, the flow velocity of the 2nd airflow Y in the exit side vicinity of the discharge opening part 201b which is a confluence | merging point of the 1st airflow X and the 2nd airflow Y can be accelerated. As a result, the venturi effect of drawing the air in the warm metal case toward the second airflow Y can be enhanced.

  In this embodiment, the case where the cooling target is both the timing generation ASIC 215 and the analog signal processing unit 213 of the image reading unit A has been described, but either one may be used. Further, the present invention can be similarly applied to a case where a component constituting the image reading unit A other than these or a component constituting the copying machine is a cooling object. The present invention is not limited to an image forming apparatus having an image reading unit such as a copying machine or a facsimile machine, but can also be applied to an image reading apparatus having no image forming unit such as a scanner device. Further, the present invention is not limited to these apparatuses, and can be similarly applied to any apparatus provided with a cooling target to be cooled.

FIG. 3 is an explanatory diagram showing the flow of airflow in the unit casing in the image reading unit of the copying machine according to the embodiment. FIG. 2 is a schematic configuration diagram showing an overall configuration of the copier. FIG. 3 is an explanatory diagram illustrating a schematic configuration of the image reading unit. Sectional drawing in the initial position of the exposure mirror unit of the image reading part. Schematic when the same exposure mirror unit is seen from the scanning direction side. Sectional drawing in the initial position of the V mirror unit of the image reading part. Schematic when the V mirror unit is viewed from the scanning direction. FIG. 3 is a functional block diagram of an electric circuit provided in the image reading unit. FIG. 3 is an explanatory diagram illustrating a schematic configuration of a cooling device provided in the image reading unit. Explanatory drawing which shows schematic structure of the cooling device when the image reading part is seen from the upper surface. Explanatory drawing when the metal case provided in the cooling device is seen from diagonally upward. Explanatory drawing when the metal case in the cooling device which concerns on a modification is seen from diagonally upward. Explanatory drawing which shows the flow of the airflow in the unit casing in a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Copier 10 Unit casing 10a Intake opening 10b Exhaust opening 12 Xenon lamp 16 Imaging lens 17 CCD image sensor 31 Photosensitive drum 110 Exposure mirror unit 120 V mirror unit 201, 301 Metal case 201a, 301a Intake opening 201b, 301b Discharge opening 201c Inclined surface 202 Intake fan 203 Exhaust fan 204 Internal fan 210 Circuit board 211 Photoelectric conversion element 213 Analog signal processing unit 215 Timing generation ASIC
301a Suction opening A Image reading unit D Image writing unit E Image recording unit

Claims (13)

A first airflow generating means for generating a first airflow hitting the object to be cooled;
A second airflow generation means for generating a second airflow that hits a second cooling object different from the cooling object without hitting the cooling object ;
With a first air stream after striking the second stream with said first cooling object second air flow generating means have been generated configured to merge with each other, than the flow rate of the first stream at the junction And a cooling device characterized in that the flow velocity of the second air stream is higher. The cooling device of claim 1.
The first airflow generation means and the second airflow generation means are constituted by a common airflow generation means,
A cooling device comprising airflow dividing means for dividing the airflow generated by the common airflow generating means into the first airflow and the second airflow. The cooling device of claim 1.
The first airflow generation means and the second airflow generation means are constituted by individual airflow generation means,
A cooling device characterized in that the first air flow generating means is arranged in the vicinity of the object to be cooled. The cooling device according to claim 3.
A case for accommodating the cooling object inside;
A discharge opening for discharging the first airflow generated by the first airflow generation means to the outside of the case;
The second airflow generating means is configured such that the second airflow flows in the vicinity of the outlet side of the discharge opening along the outer surface of the case, and the first airflow discharged from the second airflow and the discharge opening. A cooling device, characterized in that the airflow merges with each other. The cooling device according to claim 4.
It has a plate-like member carrying the cooling object,
The first air flow so that the first airflow strikes the object to be cooled from the direction inclined to the opposite side of the discharge opening with respect to the normal direction of the surface on which the object to be cooled of the plate-like member is mounted. A cooling apparatus comprising an air flow generating means. The cooling device according to claim 4 or 5,
The cooling apparatus according to claim 1, wherein the first airflow generation means is configured so that a part of the first airflow is directly discharged from the discharge opening. The cooling device according to claim 4, 5 or 6,
A cooling device, wherein the case is provided with a suction opening for sucking outside air. The cooling device according to claim 4, 5, 6 or 7,
A cooling device using a metal case as the case. The cooling device according to claim 4, 5, 6, 7 or 8,
The cooling device characterized in that the surface of the case facing the flow direction of the second air flow generated by the second air flow generating means is inclined toward the vicinity of the outlet side of the discharge opening. A light source unit for irradiating the image reading object with light;
A light receiving unit that receives reflected light reflected by the image reading object;
In an image reading apparatus having an image information generation unit that generates image information based on light received by the light receiving unit,
Having the cooling device of claim 1, 2, 3, 4, 5, 6, 7, 8 or 9,
The cooling device cools at least one component among the components constituting the image reading device as the cooling object. The image reading apparatus according to claim 10.
The image information generation unit includes a photoelectric conversion unit that photoelectrically converts light received by the light receiving unit, a drive circuit unit that drives the photoelectric conversion unit, and a signal process that processes an electrical signal obtained by the photoelectric conversion unit. Circuit part,
The image reading apparatus, wherein the at least one component as the cooling object is at least one of the drive circuit unit and the signal processing circuit unit. An image reading unit;
In an image forming apparatus having an image forming unit that forms an image on a recording material based on image information read by the image reading unit,
An image reading apparatus using the image reading apparatus according to claim 10 or 11 as the image reading unit. In an image forming apparatus that forms an image on a recording material based on image information,
Having the cooling device of claim 1, 2, 3, 4, 5, 6, 7, 8 or 9,
The cooling device cools at least one component among the components constituting the image forming apparatus as the cooling object.

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