JP6265645B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to a cooling mechanism for an electronic device used in an image forming apparatus such as an electrophotographic copying machine or an electrophotographic printer.

  In recent years, image processing apparatuses such as digital multi-function peripherals have been colorized and speeded up, and the processing speed of electronic devices mounted on a main board that controls the apparatus has also been speeded up. As the processing speed of electronic devices increases, power consumption increases, and as a result, the amount of heat generated by the devices also increases. For this reason, it is necessary to always cool efficiently during operation.

  In order to efficiently cool the components of the image processing apparatus, a gap is provided between the electrical board on which the device is provided and the peripheral devices disposed below it, and cooling air is supplied by a cooling fan substantially parallel to the electrical board. There is a technique for cooling the entire electrical board and peripheral devices by blowing air (Patent Document 1).

  Also disclosed is a technique for diverting cooling air from a cooling fan to a fixing device and an electrical board (Patent Document 2). By diverting in this way, the entire fixing device and the electrical board can be cooled.

JP 2007-48930 A JP-A-8-22237

  However, in these prior arts, although it is possible to cool the electrical board as a whole, there is a problem that an electronic device such as a CPU that is provided on the electrical board and generates a large amount of heat cannot be efficiently cooled. there were.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide an image forming apparatus capable of effectively cooling a circuit board on which a heat generating component such as a CPU having a large heat generation amount is mounted.

In order to achieve this object, the image forming apparatus of the present invention provides:
A circuit board having a first surface and a second surface which is the back surface of the first surface, on which electrical components are mounted;
A frame portion provided on the first surface side of the circuit board and supporting the circuit board;
A heating part disposed on the opposite side of the circuit board with respect to the frame part and generating heat by an image forming operation for forming an image on a recording material;
A CPU mounted on the second surface of the circuit board ;
A cover member covering the CPU;
A first cooling fan that generates a first cooling airflow in a direction along the first surface of the circuit board between the frame portion and the heat generating portion;
The second surface is attached to the cover member at a distance from the second surface, intersects the second surface of the circuit board, and faces the CPU mounted on the second surface. the cooling air flow is generated anda second cooling fan for cooling the CPU,
The frame portion may be closed the projecting direction away from the first surface, said first diverter locally directing the the first surface side of the cooling air flow the circuit board of the circuit board .

In the present invention, along with Atsushi Nobori of the circuit board is suppressed by a first cooling fan to cool the CPU on the circuit board by the second cooling fan without first cooling fan is prevented in the cooling air flow to be generated Can

1 is a schematic diagram illustrating a configuration of an image forming apparatus according to a first reference example of the present invention. It is a front view which shows the electrical equipment unit of the 1st reference example of this invention. In the first reference example of the present invention, it is a cross-sectional view showing the periphery of an electrical board supported by a frame member. In the 1st reference example of the present invention, it is a top view showing the composition of the plate-like member in which a cooling fan is provided. FIG. 4A shows a state where the cooling fan is provided, and FIG. 4B shows a state where the cooling fan is not provided. In the 1st reference example of the present invention, it is a figure showing the state of the air current at the time of cooling of an electric equipment unit. It is a perspective view of the electrical equipment unit of a 1st embodiment of the present invention. It is a schematic front view of the electrical equipment unit shown in FIG. It is a schematic sectional drawing which shows the structure of the electrical equipment unit of the 2nd reference example of this invention. It is a schematic sectional drawing which shows the structure of 2nd Embodiment electrical equipment unit of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference examples with reference to the drawings.

< First Reference Example >
(Overall configuration of image forming apparatus)
FIG. 1 is a schematic diagram showing a configuration of an image forming apparatus according to a first reference example of the present invention. An image forming apparatus A shown in FIG. 1 is an electrophotographic full color laser printer.

  The image forming apparatus A is configured to form toner images of four different colors according to image forming portions Py, Pm, Pc, and Pb through charging, exposure, development, and transfer processes. When a print command signal output from an external device such as a host computer is input, the image forming units Py, Pm, Pc, and Pb are sequentially operated.

  In the image forming units Py, Pm, Pc, and Pb, the photosensitive drum 1 that carries the toner image is rotated at a process speed of a predetermined peripheral speed. Further, the intermediate transfer belt 7 stretched around the driving roller 6a, the driven roller 6b, and the tension roller 6c is rotated at a peripheral speed corresponding to the rotational peripheral speed of the photosensitive drum 1 by the driving roller 6a. Note that the surface of the intermediate transfer belt 7 is in contact with the photosensitive drums 1 of the image forming portions Py, Pm, Pc, and Pb.

  In the image forming unit Py, the outer peripheral surface of the photosensitive drum 1 is uniformly charged to a predetermined polarity and potential by the charger 2. Next, the exposure device 3 scans and exposes the surface of the photosensitive drum 1 with laser light generated based on image information from the external device. As a result, an electrostatic latent image corresponding to the image information is formed on the surface of the photosensitive drum 1. The latent image is developed by the developing device 4 using a yellow developer, and a yellow toner image is formed on the surface of the photosensitive drum 1. In the same charging, exposure, and development processes, magenta, cyan, and black toner images are formed in the image forming unit Pm, the image forming unit Pc, and the image forming unit Pb.

  The toner images of the respective colors formed on the surface of the photosensitive drum 1 in the image forming units Py, Pm, Pc, and Pb are transferred to the intermediate transfer belt by the primary transfer roller 8 that is disposed to face the photosensitive drum 1 with the intermediate transfer belt 7 interposed therebetween. 7 are successively transferred onto the outer peripheral surface of the sheet. As a result, a full-color toner image is formed on the surface of the intermediate transfer belt 7. The transfer residual toner remaining on the surface of the photosensitive drum 1 after the toner image transfer is removed by the drum cleaner 5 and used for the next image formation.

  On the other hand, the recording material P is conveyed from the feeding cassette 10 by the delivery roller 11 to the registration roller 13 through the conveyance path 12a. Next, the recording material P is conveyed by the registration roller 13 to the secondary transfer nip Tn between the intermediate transfer belt 7 and the secondary transfer roller 14. The recording material P is nipped and conveyed by the secondary transfer nip Tn, and the toner image on the surface of the intermediate transfer belt 7 is transferred to the recording material P by the secondary transfer roller 14. The transfer residual toner remaining on the surface of the intermediate transfer belt 7 after the toner image transfer is removed by the belt cleaner 9 and used for the next image formation.

  The recording material P carrying an unfixed toner image is introduced into the nip portion of the fixing device 15 with the image carrying surface facing upward. The recording material P is nipped and conveyed at the nip portion of the fixing device 15, whereby the toner image is heated and fixed on the recording material P.

  Then, the recording material P fixed by the fixing device 15 is discharged through a discharge roller 17 onto a discharge tray 18 provided on the side surface of the image forming apparatus A.

  Further, heat from the fixing device 15 is discharged to the outside of the image forming apparatus A by the fan 130.

  Furthermore, an electrical unit 100 provided with electronic devices such as a CPU and a memory is mounted on the upper part of the image forming apparatus A.

(Configuration of electrical unit)
Next, the configuration of the electrical unit 100 will be described.

  FIG. 2 is a front view showing the electrical unit 100.

  As shown in the figure, the frame member 23 is supported by a frame support member 24. The frame member 23 accommodates and supports the electrical board. The upper part of the frame member 23 is covered with a plate-like member 21. The plate-like member 21 is provided with cooling fans 25a and 25b for locally cooling by blowing airflow directly on the electric board-like components. Further, the inside of the frame support member 24 has a hollow portion, and air is taken in from the outside of the image forming apparatus A by a cooling fan 26 (first cooling fan) and sent. Further, below the frame support member 24, heat sources 29a and 29b (processing units) such as the exposure device 3 and the developing device 4 are arranged.

  FIG. 3 is a cross-sectional view showing the periphery of the electrical board 20 (circuit board) supported by the frame member 23.

As shown in the figure, the frame member 23 of the electrical unit 100 surrounds and supports the electrical board 20. On the electrical board 20, there are provided a main CPU 50a (heat generating component, arithmetic processing circuit) that performs the entire operation and a sub CPU 50b (heat generating component, arithmetic processing circuit) that performs partial processing under the main CPU 50a. Yes. The main CPU 50a and the sub CPU 50b have a flat plate shape, and heat sinks 22a and 22b for dissipating heat from the main CPU 50a and the sub CPU 50b are provided on the upper surfaces, respectively. Note that many parts calorific value on the electrical component mounting board 20 is a main CPU50a and sub CPU 50 b.

The electrical component mounting board 20 (on the circuit board), the main CPU 50a, part of a memory or the like is provided to other sub CPU 50 b. Memory data and to temporarily interact to absorb the processing speed difference of the speed difference and parts when bridging between a plurality of types of bus standards, program when the main CPU50a and the sub CPU 50 b performs the image formation control Memorize etc.

  Furthermore, the upper part of the frame member 23 is covered with a plate-like member 21, and the plate-like member 21 is provided with cooling fans 25 a and 25 b (second cooling fans). The cooling fans 25a and 25b are provided so as to be positioned above the heat sinks 22a and 22b, respectively, and are configured such that the airflow from the cooling fans 25a and 25b directly hits the heat sinks 22a and 22b.

  That is, the cooling fans 25a and 25b are provided for locally cooling the main CPU 50a and the sub CPU 50b.

  The electrical board 20 and the cooling fans 25a and 25b are electrically connected by a connection cable and a connector (not shown). A thermistor (temperature detection means) for detecting the temperature of the main CPU 50a and the sub CPU 50b is provided so that the cooling fans 25a and 25b are blown only when the temperature of the main CPU 50a and the sub CPU 50b becomes higher than a predetermined value. You may make it control to.

  FIG. 4 is a plan view showing a configuration of the plate-like member 21 provided with the cooling fans 25a and 25b. 4A shows a state in which the cooling fans 25a and 25b are provided, and FIG. 4B shows a state in which the cooling fans 25a and 25b are not provided.

  As shown in these drawings, the cooling fans 25a and 25b are fixed by screws on substantially the ventilation openings 30a and 30b provided in the plate-like member 21. As a method for fixing the cooling fans 25a and 25b, other than screws, fasteners (fasteners, fasteners, caulking), metal or plastic stepped conical pins, metal rivets, and the like can be used. Further, bonding using an adhesive or spot welding may be used.

  FIG. 5 is a diagram illustrating a state of an air flow when the electrical unit 100 is cooled.

  The cooling fans 25a and 25b disposed above the electrical board 20 are mounted above the heat sinks 22a and 22b, and cool toward the heat sinks 22a and 22b in the directions of arrows B1 and B2 substantially perpendicular to the electrical board 20. An air flow (second cooling air flow) is formed. Thereby, the heat sinks 22a and 22b of the main CPU 50a and the sub CPU 50b disposed on the electrical board 20 can be effectively cooled.

  In addition, a cooling air flow (first cooling air flow) is formed in the direction of arrow C along the lower surface of the frame member 23 by the cooling fan 26 that generates a cooling air flow in the hollow portion of the frame support member 24. As a result, heat from the heat sources 29 a and 29 b disposed below can be shielded, and the lower surface of the electrical board 20 can be entirely cooled via the frame member 23.

< First Embodiment>
Next, an embodiment of the present invention will be described. The present embodiment differs from the first reference example in the configuration of the electrical unit. For this reason, only a different part from the 1st reference example of an electrical equipment unit is explained. In addition, the same code | symbol is attached | subjected to the part which is the same as or similar to a 1st reference example, and the overlapping description is abbreviate | omitted.

  FIG. 6 is a perspective view of the electrical unit 100a of the present embodiment.

  As shown in the figure, a part of the frame member 23 a that supports the electrical board 20 is supported by a frame support member 24. The frame member 23a is provided with flow dividing members 27a and 27b.

  FIG. 7 is a schematic front view of the electrical unit 100a shown in FIG.

  As shown in the figure, flow dividing members 27 a and 27 b (flow dividing means) are provided on the back surface of the frame member 23. The flow dividing members 27 a and 27 b are for guiding a part of the airflow generated by the cooling fan 26 to a predetermined region of the electrical board 20. As shown in FIG. 6, since a part of the bottom surface of the frame member 23 is supported by the frame support member 24, flow dividing members 27 a and 27 b can be provided on the back surface of the frame member 23. .

  It is desirable that the flow dividing members 27a and 27b are disposed in the vicinity of the portion where the heat generation amount is high on the lower surface of the electrical board 20. Thereby, the direction of the cooling airflow of the cooling fan 26 is changed in the directions of arrows D1 and D2 by the diversion members 27a and 27b provided in the frame member 23. That is, the cooling airflow formed substantially parallel to the electrical board 20 forms flow paths in the directions of arrows D1 and D2 toward the lower surface of the electrical board 20 by the diversion members 27a and 27b. Therefore, the cooling fan 26 can not only cool the lower surface of the electrical board 20 as a whole, but also locally cool a portion where the amount of heat generation is large on the lower surface of the electrical board 20.

  Note that when a plurality of flow dividing members are provided as in this embodiment, care must be taken so that the flow dividing members do not interfere with the flow of airflow. For example, since the flow dividing member 27a is downstream of the flow dividing member 27b, there is a possibility that the flow dividing member 27b may be affected by changes in the air flow. In this case, it is desirable that the flow dividing member 27a and the flow dividing member 27b do not overlap each other. When the flow dividing member 27a and the flow dividing member 27b overlap, it is desirable to make the area of the flow dividing member 27a larger than the area of the flow dividing member 27b so that the influence of the flow divided by the flow dividing member 27b is minimized.

< Second Reference Example >
Next, a second reference example of the present invention will be described. This reference example differs from the first reference example in the configuration of the electrical unit. For this reason, only a different part from the 1st reference example of an electrical equipment unit is explained. In addition, the same code | symbol is attached | subjected to the part which is the same as or similar to a 1st reference example, and the overlapping description is abbreviate | omitted.

FIG. 8 is a schematic cross-sectional view showing the configuration of the electrical unit 100b of this reference example .

  As shown in the figure, a diversion member 28 (diversion means) is provided in the ventilation opening 30a of the cooling fan 25a in the plate-like member 21. As a result, the cooling air flow of the cooling fan 25a is diverted in the direction of the arrow E between the heat sink 22a disposed immediately below and other regions (predetermined regions). For this reason, the cooling of the main CPU 50a by the heat sink 22a and other areas can be simultaneously cooled, that is, local cooling and wide range cooling can be performed simultaneously.

Second Embodiment
Next, another embodiment of the present invention will be described. This embodiment is different from the first reference example in the configuration of the electrical unit. For this reason, only a different part from the 1st reference example of an electrical equipment unit is explained. In addition, the same code | symbol is attached | subjected to the part which is the same as that of a 1st reference example , 1st Embodiment, and a 2nd reference example, and the overlapping description is abbreviate | omitted.

  FIG. 9 is a schematic cross-sectional view showing the configuration of the electrical unit 100c of the present embodiment.

As shown in the figure, in this embodiment, the flow dividing members 27a and 27b described in the first embodiment and the flow dividing member 28 described in the second reference example are provided. For this reason, the cooling airflow from the cooling fan 26 cools the lower surface of the electrical board 20 and is diverted in the directions of arrows D1 and D2 by the diversion members 27a and 27b and guided to a predetermined portion on the back surface of the electrical board 20. . Further, the cooling airflow from the cooling fan 25a directly hits the heat sink 22a, the main CPU 50a is cooled, and a part of the current is diverted in the direction of arrow E by the diversion member 28, and is led to a different area from the main CPU 50a of the electrical board 20. It cools this area.

DESCRIPTION OF SYMBOLS 20 ... Electrical board | substrate 21 ... Plate-shaped member 22a, 22b ... Heat sink 23 ... Frame member 24 Frame support member 25a, 25b ... Cooling fan 26 ... Cooling fan 27a, 27b ... Splitting member 28 ... Splitting member 29a, 29b ... Heat source 30a, 30b ... Ventilation opening 100 ... Electrical unit A ... Image forming apparatus

Claims (10)

An image forming apparatus for forming an image, comprising a first surface and a second surface that is the back surface of the first surface, and a circuit board on which an electrical component is mounted;
A frame portion provided on the first surface side of the circuit board and supporting the circuit board;
A heating part disposed on the opposite side of the circuit board with respect to the frame part and generating heat by an image forming operation for forming an image on a recording material;
A CPU mounted on the second surface of the circuit board ;
A cover member covering the CPU;
A first cooling fan that generates a first cooling airflow in a direction along the first surface of the circuit board between the frame portion and the heat generating portion;
The second surface is attached to the cover member at a distance from the second surface, intersects the second surface of the circuit board, and faces the CPU mounted on the second surface. the cooling air flow is generated anda second cooling fan for cooling the CPU,
The frame portion may be closed the projecting direction away from the first surface, said first diverter locally directing the the first surface side of the cooling air flow the circuit board of the circuit board Image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the second cooling airflow is directed from the second cooling fan to the second surface substantially perpendicularly to the second surface of the circuit board . The image forming apparatus according to claim 1 , wherein the diversion unit guides the first cooling airflow to a predetermined region of the first surface of the circuit board.   4. The image forming apparatus according to claim 1, further comprising a flow dividing unit that guides the second cooling airflow to a predetermined region of the circuit board that is different from the CPU. 5. .   The image forming apparatus according to claim 1, wherein the first cooling fan generates the first cooling airflow in a direction substantially parallel to the circuit board. 6. The first cooling fan according to claim 1, wherein the first cooling fan generates the first cooling airflow in order to cool the first surface of the circuit board. 7. Image forming apparatus.   The said 1st cooling fan produces | generates a said 1st cooling airflow in order to interrupt | block the heat which goes to the said circuit board from the said heat-emitting part, The Claim 1 thru | or 6 characterized by the above-mentioned. The image forming apparatus described.   8. The image forming apparatus according to claim 1, wherein the CPU is provided with a heat sink for radiating heat from the CPU, and the second cooling airflow is applied to the heat sink. 9. . Comprising temperature detecting means for detecting the temperature of the CPU;
9. The second cooling fan generates the second cooling airflow when the temperature of the CPU detected by the temperature detecting unit is higher than a predetermined value. The image forming apparatus according to claim 1.   The image forming apparatus according to claim 1, wherein the heat generating unit is an exposure apparatus or a developing apparatus used for forming an image of the image forming apparatus.

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