JP3450904B2 - Image forming device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus , and in particular, shuts off heat generated from a heat source inside the image forming apparatus to other apparatus or cools a heat source including a motor. The structure for doing.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus typified by a laser printer, a copying machine, etc. exposes a photosensitive drum to form an electrostatic latent image and visualizes the electrostatic latent image with toner to form a sheet. There is a type in which a toner image on a sheet is transferred and then fixed by a fixing device.

This fixing device has a built-in heat source such as a halogen lamp, and heats the inside of the image forming apparatus. In particular, since the cleaning device that scrapes and collects the toner remaining on the photosensitive drum after transfer to the paper is located on the fixing device side of the photosensitive drum, it is affected by the temperature of the fixing device and the collected toner melts due to heat. Not only will the toner collect and hinder the recovery of the toner, but if the toner is reused, the print quality will deteriorate. To eliminate this,
A duct for passing an air flow is arranged between the fixing device and the photosensitive drum so that the heat generated by the fixing device is almost shut off from the photosensitive drum.

Further, in a small-sized image forming apparatus, it is almost 1
The individual motors drive the photosensitive drum, the rollers in the fixing device, and the sheet conveying rollers. Therefore, the motor is used under a very high load and generates a large amount of heat. Further, among the circuit elements on the control board that electrically control the operation of the image forming apparatus, there are elements that generate a great amount of heat. In order to cool these motors and substrates, it is also practiced to take a cooling air flow into the image forming apparatus with a dedicated fan.

[0005]

However, the cooling efficiency is poor in the case where the air flow is generated indiscriminately in the image forming apparatus. For example, if air flows uniformly from one side to the other in the image forming apparatus or the motor housing space, the air flow comes into contact with only one side of the motor, and the motor is not cooled sufficiently. The air flow passing through the duct between the fixing device and the photosensitive drum is inefficient when it is reused for cooling the motor, the substrate, etc. because the position and direction of the air blow are specified.

Therefore, it is only necessary to install a plurality of fans for each purpose, but it is very expensive.

The present invention efficiently cools the motor and the control board, and effectively reuses the air flow passing through the duct between the fixing device and the photosensitive drum to achieve the cooling.

[0008]

To achieve the above object, an image forming apparatus of the present invention comprises a frame, a photosensitive drum which is supported by the frame and on which a toner image is formed, and the toner image is transferred. A fixing device that heats and fixes the same image on a sheet of paper, and is disposed between the photosensitive drum and the fixing device, and in a direction bridging between the pair of side walls of the frame.
An image forming apparatus and a duct , which is arranged and passes an air flow for substantially blocking the heat generated by the fixing device from the photosensitive drum.
Control board for electrically controlling the operation of the
A fan that is disposed on one of the pair of side walls and that generates an air flow, and that is connected to one end of the duct,
The generated air flow is divided, and one of the divided flows is the duct
Guide-out, a shunt wall to guide the diverted other to the control circuit,
Disposed on the other of the pair of side walls of said frame, said frame, a motor housing portion formed in a concave shape for housing the motor, as well as connect other end of the duct to the motor housing portion, from the duct An introduction path for introducing the air flow into the motor housing part is provided in the motor housing part so that the air flow spreads almost entirely in the motor housing part.
And a discharge port for discharging an air flow toward the control board .

Further , in claim 2, the image according to claim 1
In the image forming apparatus, the motor housing portion has the concave shape.
Place a space between the surrounding wall to be formed and the outer peripheral surface of the motor.
Housing the motor, and the introduction path is close to the surrounding wall.
Introduce the air flow into the motor housing from the tangential direction
The motor accommodating portion has an opening
Has a guide wall extending toward almost the center.

Further , in claim 3, the image according to claim 2
In the image forming apparatus, the motor housing may further include
Between the inner wall that forms the concave shape and one end surface of the motor
A space is provided to accommodate the motor, and the guide wall of the introduction path is
It extends between the inner wall and the end surface of the motor.

According to a fourth aspect, the image of the second aspect is provided.
In the image forming apparatus, the outlet has the guide wall in between.
It is placed at a position facing the opening of the introduction path.

[0012]

[0013]

In the above structure, the air flow generated by the fan is divided by the flow dividing wall , and one of the divided air flows .
Airflow is introduced into the motor housing through the duct. The heat generated in the fixing device is almost shut off to the photosensitive drum side by the air flow in the duct, and does not affect the cleaning of the toner. Furthermore airflow Ru through the duct, to be guided to spread substantially the entire inside motor housing portion,
The motor is cooled efficiently. Also, flow in the motor housing
Air is Ru guided from the outlet to the control board. Meanwhile, minutes
The other air flow diverted by the flow wall is guided to the control board.
Be done.

More specifically, the airflow passing through the duct is introduced into the motor housing portion from a substantially tangential direction, and draws a substantially circle toward the center between the end surface of the motor and the inner wall of the motor housing portion. To be guided. After that, a flow is formed so as to surround the whole motor, and the whole motor is efficiently cooled.

[0015]

As described above, the air flow generated by one fan shuts off heat between the fixing device and the photosensitive drum,
It is used efficiently for cooling motors and substrates.

[0017]

The present invention will be described in detail below with reference to embodiments embodying the present invention in a laser printer.

FIG. 1 shows a schematic side cross section of the printer 2. The printer 2 of this embodiment includes a paper feeding device 3. The sheets P stacked and placed in the sheet feeding device 3 are separated one by one by the sheet feeding roller 4 and the separation pad 5, and are conveyed to the image forming unit 9 inside the main body via the pair of conveying rollers 6. The image forming unit 9 includes the photosensitive drum 7, the transfer roller 8, and the toner supply unit 1.
0, an exposure unit 17, a fixing device 13, and the like.

The exposure unit 17 irradiates the photosensitive drum 7 with laser light emitted from a laser emitting section (not shown) through the rotating polygon mirror 14, lens 15 and reflecting mirror 16. On the surface of the photosensitive drum 7, which is uniformly charged by the charger 23, an electrostatic latent image is formed by laser light. The toner supply unit 10 supplies the toner contained in the toner cartridge 28 to the surface of the photosensitive drum 7 to visualize the electrostatic latent image on the photosensitive drum. The visualized toner image is transferred to the sheet conveyed between the photosensitive drum 7 and the transfer roller 8. The toner remaining on the photosensitive drum 7 is scraped off by the cleaning device 21,
Be recovered. Then, the collected toner is conveyed to the toner supply unit 10 by a well-known conveying means (not shown), mixed with new toner, and reused.

The sheet on which the toner image is transferred is fixed by the fixing device 1.
3 is passed between the heating roller 12 and the pressure roller 11, the toner is heated and melted, and the toner image is fixed. After fixing, the paper is discharged to the outside by the discharge roller pair 24.

The heating roller 12 incorporates a heat source such as a well-known halogen lamp, which is not shown. An airflow for shutting off the heat generated by the heating roller 12 to the cleaning device 21 and the photosensitive drum 7 is passed between the fixing device 13 and the photosensitive drum 7, more specifically, between the heating roller 12 and the cleaning device 21. The duct 22 is arranged.

FIG. 2 shows a perspective view of the frame 25. The frame 25 is composed of a pair of side walls 25R, 2
5L and a bottom wall 25B connecting both side walls. The photosensitive drum 7 and the fixing device 13 are arranged so as to bridge each axial direction between the side walls 25R and 25L, and are fixed to the side walls. The duct 22 also extends in the bridging direction between the side walls 25R and 25L. The duct 22 is made of a material having good thermal conductivity such as aluminum, and is fixed to the side surface of the fixing device 13 along the heating roller 12.

The photosensitive drum 7 and the heating roller 12 of the fixing device 13 are fixed to the frame 25, and the gear 2 driven by the motor 26 (FIG. 3) through the gear train 27.
8 and 29 (FIG. 2) are engaged with driven gears (not shown), which are rotationally driven by a common motor 26 thereof. Motor 2
6 and the gear train 27 are fixed to a pair of mounting plates 32 and 33, and are fixed to the left side wall 25L of the frame. At the same time, the motor 26 is arranged in a motor housing portion 30 formed in a substantially cylindrical concave shape on the left side wall 25L, and one mounting plate 33 to which the motor 26 is fixed covers the open surface of the motor housing portion 30. Fixed. The motor accommodating portion 30 is formed sufficiently larger than the motor 26, and is located between the peripheral wall 30 </ b> B forming the concave shape and the outer periphery of the motor 26, and the inner wall 30.
Spaces are provided between C and the rear end of the motor 26, respectively.

A cooling fan 35 is fixed to the right side wall 25R of the frame so as to face an opening 36 (FIG. 3) formed in the side wall thereof. In a portion 37 formed by projecting from the bottom wall 25B so as to surround the opening 36 on the inside of the right side wall, a diversion wall 37B inclined so as to divide the opening 36 into upper and lower parts is formed, and the diversion An opening 37C is formed above the wall 37B. The airflow generated by the fan 35 is divided by the flow dividing wall 37B into upper and lower portions of the bottom wall 25B of the frame.

The duct 22 has an opening 22C on the lower surface of one end that faces the opening 37C, and the other end is closed by a wall 38 standing on the upper surface of the motor accommodating portion 30. Wall 3
The upper part of the motor housing 30 closer to the duct 22 than 8 is
It is formed as an introduction portion 39 that introduces an airflow from the inside of the duct 22 into the motor housing portion 30.

As shown in FIG. 4, the introducing portion 39 is formed so as to extend substantially in the tangential direction of the motor accommodating portion 30 and in the vertical direction, and has an opening 39B at the upper end for connecting to the duct 22. Further, a guide wall 39C extending from the lower end of the above-mentioned vertically extending portion of the introducing portion 39 so as to extend toward the approximate center of the motor housing portion 30 is formed. The guide wall 39 C is enters between the rear end and the back wall 30C of the motor 26. Opening 3 of the introduction part with the guide wall 39C in between
A discharge port 40 is formed in the motor housing portion 30 at a lower position facing the 9B. The introduction portion 39 including the guide wall 39C is provided in the frame 25 together with the motor housing portion 30.
It is made of synthetic resin material.

A bottom plate 41 is fixed to cover the lower surface of the frame 25 below the bottom wall 25B.
In the space between the bottom wall 25B and the bottom plate 41, the control board 1 including a circuit for electrically controlling the image forming apparatus, a power supply, and the like.
8, 19, and 20 are arranged. Some control boards 18 are located downstream of the airflow divided downward by the flow dividing wall 37. The other control board 19 is located on the downstream side of the discharge port 40 of the motor housing portion 30.

The air flow generated by rotating the fan 35 is divided into an upper part and a lower part by the flow dividing wall 37B. The air flow divided above has openings 37C and 22C.
It is guided to the inside of the duct 22 through and absorbs the heat generated by the heating roller 12 of the fixing device 13, and substantially shuts off the heat to the photosensitive drum 7 and the cleaning device 21. As a result, the toner remaining on the photosensitive drum 7 and the cleaning device 21
The problem that the toner collected in step 1 is melted by the heat from the fixing device 13 is solved.

The air flow passing through the duct 22 is introduced into the introduction section 3
It is introduced into the motor accommodating portion 30 through the opening 39 </ b> B of 9.
The air flow is first introduced between the rear end of the motor 26 and the inner wall 30C, and is guided by the guide wall 39C to the motor housing portion 30.
Towards the center of. The airflow is directed upward along the wall 30B around the motor housing portion 30 and circulates in the annular space between the outer periphery of the motor 26 and the wall 30B around the motor 26 to efficiently cool the motor 26. Duct 22
The air flow passing through the inside is about 1 before reaching the motor housing portion 30.
Although it has risen by 5 degrees C, it is sufficient to cool the motor 26.

The air flow circulating around the outer periphery of the motor 26 descends toward the discharge port 40, and the control substrate 19 is discharged from the discharge port 40.
And the control board 19 is cooled. After that, the airflow is discharged to the outside from the opening 42 provided in the left side wall 25L. A part of the air flow circulating in the motor housing portion 30 may be discharged to the outside from an opening (not shown) formed in the mounting plate 33 as appropriate.

The air flow divided downward by the flow dividing wall 37B cools the control board 18, and then the right side wall 25
It is emitted to the outside from an opening (not shown) provided in R as appropriate.

[0032]

As described above, according to the present invention, the airflow is generated so as to surround the entire motor, and the entire motor can be efficiently cooled. Further, cooling of the control board and interruption of heat between the fixing device and the photosensitive drum can be effectively performed by the air flow generated by one fan.

[0033]

[Brief description of drawings]

FIG. 1 is a schematic side sectional view of a laser printer.

FIG. 2 is a perspective view of a frame.

FIG. 3 is a sectional view taken along line CC of FIG.

4 is a cross-sectional view taken along the line AA of FIG.

5 is a sectional view taken along line BB of FIG.

[Explanation of symbols]

2 printer 7 Photosensitive drum 13 Fixing device 19 Control board 22 duct 25 frames 26 motor 30 motor housing 35 fans 39 Introduction 39C guide wall

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H02K 9/00-9/28 H05K 7/20 G03G 13 / 00,15 / 00

Claims (4)

(57) [Claims] 1. A frame, a photosensitive drum which is supported by the frame and on which a toner image is formed, a fixing device which heats and fixes the image on a sheet onto which the toner image is transferred, and the photosensitive drum and the fixing device. Located between the devices and
A duct disposed between the pair of side walls of the frame to bridge the air flow for substantially blocking the heat generated by the fixing device from the photosensitive drum, and a control board for electrically controlling the operation of the image forming apparatus. And a fan disposed on one of the pair of side walls of the frame for generating an air flow, and connected to one end of the duct for generation by the fan.
The separated air flow and guide one of the divided flow to the duct.
Can, a shunt wall to guide the diverted other to the control circuit, disposed on the other of the pair of side walls of said frame, said frame, a motor housing portion formed in a concave shape for housing the motor, the other of the duct An end is connected to the motor accommodating part, and an introduction path for introducing the air flow from the duct into the motor accommodating part is provided in the motor accommodating part so that the air flow is distributed to almost the entire motor accommodating part. , Empty towards the control board
An image forming apparatus having a discharge port for discharging an air flow . 2. The image forming apparatus according to claim 1, wherein the motor accommodating portion accommodates the motor with a space provided between a peripheral wall forming the concave shape and an outer peripheral surface of the motor, and the introduction. The image forming apparatus includes a passage having an opening for introducing the airflow into the motor housing portion from a substantially tangential direction of the surrounding wall, and a guide wall extending from the opening toward a substantially center of the motor housing portion. 3. The image forming apparatus according to claim 2 , wherein the motor accommodating portion further accommodates the motor with a space provided between an inner wall forming the recess and one end surface of the motor. An image forming apparatus in which the guide wall of the introduction path extends between the inner wall and the end surface of the motor. 4. The image forming apparatus according to claim 2 , wherein the discharge port is provided with the guide wall in between.
Image forming apparatus provided at a position facing the opening of the .