JP3312819B2 - Ventilation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ventilation device for discharging heat or discharge products generated in an image forming section of an electrophotographic image forming apparatus such as an electrophotographic copying machine, a printer, a facsimile, etc. It relates to an improvement for flow control.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus such as an electrophotographic copying machine, a printer, and a facsimile, optical image information such as original reflected light is radiated onto a photosensitive member uniformly charged in advance. Thus, an electrostatic latent image is formed, and a toner image obtained by visualizing the electrostatic latent image with toner from a developing device is transferred and fixed on recording paper to form an image. In an electrophotographic image forming process, discharge products such as ozone are generated by heat generated from heat-generating components such as an exposure lamp and a fixing device, and discharge of a corotron such as a charger and a transfer device. When the generated heat accumulates in the apparatus, the temperature inside the apparatus abnormally rises, and has various adverse effects on electric parts, electronic parts, mechanical parts, and the like, and ozone affects the photoconductor and other components. Has adverse effects such as deterioration. For this reason, the conventional image forming apparatus is provided with a ventilating device for forming a constant airflow inside and ventilating air inside and outside the apparatus.

Conventionally, as a ventilation device for discharging heat or discharge products generated inside an image forming apparatus, a method of reducing noise by providing a shielding plate inside an air suction port (Japanese Patent Laid-Open No. Sho 62)
No. 749), and a method of reducing the number of revolutions of the blower fan during standby of the image forming apparatus to reduce noise. FIG. 8 shows an example of the former ventilation device in which a shielding plate is provided inside the air suction port, and a fan 31 for feeding air flow into the device, a dual-purpose housing 32 and a duct 32, and a vertical shielding plate 33. Is configured as shown in the figure. The arrow indicates the air flow, and as a result of the vertical shield plate 33, the noise from the fan 31 or the like can be shielded from the outside without changing the suction amount for sending the air flow into the apparatus (Japanese Patent Laid-Open No. Sho 62). -749). However, the former method uses the shielding plate 33
Is fixed, so even if you can reduce the noise,
The air flow could not be freely adjusted, and as a result, the air flow strongly hit the ears of the developing sleeve during the development, causing a problem that the toner of the developer was scattered in the apparatus.
In addition, the latter method requires not a general inexpensive blower fan that can be used with an AC input power supply, but a special blower fan whose rotation speed changes with voltage and frequency, and an electric control circuit that controls voltage and frequency. And there is a problem that it becomes an expensive ventilation device.

[0004]

In the method of providing a shield plate inside the air inlet as described above, since the shield plate is fixed and the air flow cannot be adjusted, noise can be reduced. The air flow cannot be freely adjusted, and the air flow strongly hits the ears of the developing sleeve during development, causing a problem that the toner of the developer is scattered in the apparatus. Also, in the method of reducing the number of rotations of the blower fan during standby of the image forming apparatus to reduce noise, a special inexpensive blower fan that can be used with an AC input power supply is used. A blower fan and an electric control circuit for controlling the voltage, frequency, and the like are required, which causes a problem that the cost is greatly increased.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and has a structure in which two or more shield plates provided alternately and opposed to each other in an air duct forming an air flow passage are rotated. Provide a low-priced ventilation device that adjusts the air flow by changing the protruding height of the shielding plate during image formation and during standby, and can reduce toner diffusion and noise during standby. It is intended to be.

[0006]

In order to achieve the above object, the present invention relates to a ventilating device provided for discharging heat and discharge products generated inside an image forming apparatus to the outside of the apparatus. A blower fan that causes an air flow to discharge the discharge products to the outside of the machine, a blower duct that is arranged across the blower fan and communicates inside and outside the device, and alternately faces the inner wall of the blower duct, respectively. Rotating means for rotatably supporting the base end of each shielding plate with the two or more shielding plates provided and the inner wall of the ventilation duct so that the height of the shielding plate protruding into the ventilation path can be changed. When the shielding plate has a maximum protruding height, a space is formed between the shielding plate and the inner wall of the facing ventilation duct, and the tip portions of the shielding plates overlap with each other when viewed from the blowing direction. It is characterized by doing. Further, the rotating means is rotated to a position where the protruding height of the shielding plate is minimized so that the air flow is maximum while the image forming apparatus is performing image formation, and the image forming apparatus is not performing image formation. During standby, the shield plate is configured to rotate until the height of the shielding plate is maximized so that the airflow is minimized. Also, in the air duct,
Alternatively, an air flow detecting means for detecting an air flow rate is provided on a side path directly connected to the air duct, and according to a detection value of the air flow detecting means, the turning means is turned to rotate the height of the shielding plate. Is changed.

[0007]

The ventilation device constructed as described above is provided with a ventilation duct which is disposed with a ventilation fan interposed therebetween and communicates with the inside and outside of the image forming apparatus, and two or more ventilation ducts which are alternately provided in the ventilation duct. Since the shielding plate and the rotating means for rotating the shielding plate are provided, it is possible to freely change the protruding height of the shielding plate in the air duct using the rotating means. Therefore, during image formation, the height of the shielding plate is rotated until the height of the shielding plate is minimized so that the air flow is maximized, and the height of the shielding plate is reduced so that the air flow is minimized during standby. Since it can be easily rotated to the maximum, heat is released by the maximum airflow when the heat generation amount of image formation is large, and the heat generation amount is not so large during standby when no image is formed,
The air flow can be further reduced, noise can be prevented, and the toner remaining on the photosensitive drum at the time of development is not diffused.

[0008]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a main part of a color copying apparatus (an image forming section of a color copying machine) which is one of typical examples of an electrophotographic image forming apparatus. Since it is known, a part related to the effect of the present invention will be described here. The surface of the photosensitive drum 21, which rotates at a constant speed in the counterclockwise direction, is uniformly charged by the charger 22 and then optically written by an optical writing device (not shown) to form an electrostatic latent image. For forming a color image, a Br (black) developing unit 23, a Y (yellow) developing unit 24, an M (magenta) developing unit 25, and a C (cyan) developing unit 26 are sequentially arranged around the photoconductor. . Each of the developing devices rotates each of the Br, Y, M, and C developing rollers that contact an ear of developer with the surface of the photosensitive drum 21 in order to develop an electrostatic latent image formed on the photosensitive drum 21. Sleeves (23a, 24a, 25a, 26a), and Br, Y, M, C developing paddles (23b, 24b, 25b, 26b), which rotate to draw up and agitate the developer, and B
It is composed of a toner concentration sensor for developer (23c, 24c, 25c, 26c) for r, Y, M, C.

On the other hand, in order to remove discharge products such as ozone generated by the discharging operation of the charger 22, the airflow carried from the air duct flows from the upper side (arrow A) of the charger 22 to the lower side. And hits the surface of the photosensitive drum 21 and is divided mainly into two directions. One is the direction in which optical writing is performed by an optical system (not shown) (arrow B), and the other is the direction of the Br developing sleeve 23a (arrow C). If the air flow in the direction of the arrow C is strongly applied while the developer is raised with the ear of the developer between the Br developing sleeve 23a and the surface of the photosensitive drum 21, the toner constituting the ear is scattered. And a clear toner image is not formed.

FIG. 2 is a diagram showing a state in which an airflow is sent from outside the housing 27 of the image forming apparatus to the drum unit 20 including the photosensitive drum 21 and the charger 22 through the air duct 2. The air flow is indicated by black arrows, and in particular, the air flows A1, A2, and A3 sent from the upper side of the charger 22 correspond to the charger 2 in FIG.
2 shows a state corresponding to the airflow of arrow A sent from above. In the present invention, as described above, the developing sleeve of the developing device closest to the charger, for example, Br
Before the developing sleeve 23a raises the ears of the developer between the developing sleeve 23a and the surface of the photosensitive drum 21 to perform development, the air flow in the air duct 2 is reduced so that toner is not scattered, and noise is reduced. It is configured to reduce. In the above description, the ventilation device is described as being in the intake state in which the air flow is sent into the image forming apparatus. However, this is because it is easier to understand this effectively, and the ventilation state in which the air flow is sent out of the image forming apparatus. However, (in that case, the directions of the arrows of the air flow in FIGS. 1 and 2 are all opposite directions). The effect of the present invention is the same.

FIG. 3 shows an embodiment of a ventilation device according to the present invention, in which a ventilation duct 2 is provided which is provided with a ventilation fan 1 interposed therebetween and communicates with the inside and outside of the image forming apparatus. It is a figure showing the state where an air flow is sent into (inside of an apparatus). In the figure, two shielding plates 3 are provided alternately so as to face the inner wall of the air duct 2, and one end of each shielding plate 3 is rotatably attached to the wall of the air duct 2. The height of the shielding plate 3 can be changed by rotating about the reference numeral 4 as indicated by a dotted line. In other words, the turning means 4 is provided at the base end of the shielding plate 3.

When the height of each shield plate 3 (projection height into the air passage) is maximized, there is a space between the end of the shield plate 3 and the inner wall surface facing the shield plate 3. Although the overlap amount is indicated by l (ell) in the figure, it has been found by actual measurement that up to a certain value (about 20 mm in the experimental result), the air flow rate decreases as l increases. Further, it is known that the noise is reduced in the range where the air flow rate is reduced due to the above-described effect of blocking the air from the outside in FIG. Therefore, if the height of the shield plate 3 is adjusted so that the overlap amount l (approximately 20 mm) at which the air flow rate is reduced and the noise reduction effect is greatly increased, a simple shield plate 3 can be obtained.
The expected effect can be obtained only by the opening and closing work.

That is, in order to solve the problem that the noise of the blower fan 1 of the ventilating device is jarring when most of the operating mechanisms of the image forming apparatus are stopped, the ventilating device having the configuration shown in FIG. When the generation of heat during image formation is large, the height of the shielding plate 3 is rotated to a minimum (see FIG. 4 (B)) so that the air flow rate is maximized, When the occurrence of is small, if the height of the shielding plate 3 is rotated to the maximum (see FIG. 4A) so that the air flow rate is minimized, the noise can be reduced and the problem can be solved.
Further, the ventilation device having the configuration as shown in FIG. 3 is used to remove discharge products such as ozone generated by the discharging operation of the charger 22 as shown in FIG.
As described above, the air flow rate is minimized immediately before the Br developing sleeve 23a stands up against the surface of the photosensitive drum 21 for developing the developer with the spikes of the developer. In addition, if the height of the shielding plate 3 is adjusted, the airflow hitting the toner when the cutting operation is started is minimized, so that the scattering of the toner can be prevented.

FIG. 4 is a view showing an example of the structure of a mechanism for rotating the shielding plate 3. FIG. 4A shows a state in which the rotating means 4 is rotated to the maximum in a counterclockwise direction. In this figure, the height between the air duct 2 and the shielding plate 3 is 90 degrees. The rotation means 4 is, for example, a rotation center shaft 4a convex at the center.
The rotation center 4a can be rotated by fitting the rotation center 4a into a concave portion fitted in the side plate of the air duct 2. A knurled portion (or a gear portion) 4b is provided at a part of the outer peripheral portion of the rotating means 4, and the rotation is fixed by fitting the stop finger 2a of the blower duct 2 to the valley portion. . FIG. 4B shows that the angle of the shielding plate 3 is 0 degree, that is, the shielding plate 3 is parallel to the air duct 2.
Is designed so that the shield plate 3 is received in the groove 2b of the side plate of the ventilation duct 2 as shown in the figure, so that the height of the shield plate 3 is minimized, and does not hinder the air flow of the ventilation duct 2. . The rotation limit in the clockwise direction in FIG.
One end of b is determined by being stopped by the stop finger 2a. The turning means 4 is turned by a motor (not shown) or the like.

FIGS. 5 and 6 show an example in which the shielding plate 3 is automatically rotated within a range of 0 to 90 degrees and can be stopped at a desired angle. As shown in FIG. A worm wheel portion 4c is provided on an outer peripheral portion of the motor 4, and is configured to mesh with an output shaft 8 (worm) of a DC motor 7 provided on the image forming apparatus side. FIG. 6 is an overall view showing the configuration of each part. The blower fan 1, the blower duct 2, the shielding plate 3, and the rotating means 4 are the same as those in FIG. The DC motor 7 drives the output shaft 8 to rotate, drives the meshed worm wheel portion 4c, rotates the rotating means 4, and sets the shielding plate 3 to a predetermined projecting position. If the polarity of the voltage applied to the DC motor 7 is reversed, the shielding plate 3 is rotated in the opposite direction.

FIGS. 7A and 7B are diagrams showing a configuration and an operation for obtaining a target air flow rate by changing the height of the shielding plate 3. FIG. An air flow detecting means 5 for detecting an air flow rate is installed in the inside, and an output of the air flow detecting means 5 is guided to a detection controller 6a. The detection controller 6a outputs a voltage to be applied to the DC motor 7 in comparison with the control value X in order to obtain a target air flow rate. The DC motor 7 rotationally drives the output shaft 8 according to the output value of the detection controller 6a, rotates the rotating means 4 through the meshing worm wheel portion 4c, and changes the protruding height of the shielding plate 3. As an example of such an airflow detecting means 5, a thermistor that generates heat by applying a constant current is placed in an airflow, and the airflow is detected by measuring a resistance value that changes according to a heat radiation condition. Is used. Data about the air flow rate input from the air flow detection means 5,
Data on the correspondence between the amount of protrusion of the shielding plate 3 (the amount of rotation and the direction of the rotation means 4 = the voltage to be applied to the DC motor 7) required to bring the current air flow rate to the target value is as follows. Are stored as a table in the detection control unit 6a or a control unit (not shown) of the image forming apparatus main body.

FIG. 7 (B) shows a side road 2A derived from an opening 2a formed in the side wall of the air duct 2 and the side road 2A.
This is an example in which the air flow detecting means 5 for detecting the air flow rate is provided in the first embodiment, and utilizes the fact that the air pressure of the armpit 2A changes depending on the speed of the air flow. The air pressure detecting means 5 such as a manometer for detecting the air pressure is used for detecting the air pressure without the sidewalk. The configuration and operation after the detection controller 6b are shown in FIG.
Same as (A). Therefore, as described above, FIG.
The shielding plate 3 having the rotating means 4 as described above can be made very inexpensive, and the adjustment of the air flow is simple and reliable.

[0018]

As described above, the present invention provides a ventilation duct which is provided with a ventilation fan interposed therebetween to form an air flow passage communicating between the inside and the outside of the image forming apparatus, and which faces the inside wall of the ventilation duct. And two or more shielding plates whose tips overlap each other at the time of maximum protrusion, and a rotating means for rotating the shielding plate, so that it is shielded in the air duct using the rotating means. The height of the plate can be freely changed. Then, during image formation, the airflow flowing into the apparatus is maximized, so that the height of the shielding plate is rotated to a minimum, and during standby, the airflow is minimized. It is easy to rotate the shielding plate until the height is maximized. As a result, when the amount of heat generated during image formation is large, heat is radiated with the maximum airflow, and during standby when image formation is not performed, the amount of generated heat is not so large, so that the airflow can be reduced, Noise can be prevented from being generated, and the toner remaining on the photosensitive drum at the time of development is not diffused, so that deterioration in image quality can be prevented.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a main part of a color copying apparatus as a typical example of an image forming apparatus.

FIG. 2 is an explanatory diagram illustrating a main part of a ventilation device according to an embodiment of the present invention.

FIG. 3 is a block diagram of a main part of the ventilation device according to the embodiment of the present invention.

4 (A) and 4 (B) are explanatory views illustrating rotation of a main part of a shielding plate and a rotation unit of a ventilation device according to an embodiment of the present invention.

FIG. 5 is an explanatory diagram illustrating a main part of a rotating means of a ventilation device and an output shaft of a motor, showing an embodiment of the present invention.

FIG. 6 is a block diagram of a main part for opening and closing a shielding plate of the ventilation device according to the embodiment of the present invention.

FIGS. 7A and 7B are block diagrams of a main part of the ventilation device according to the embodiment of the present invention, in which airflow detecting means is provided.

FIG. 8 is a side view of a main part of an example of a conventional ventilation device.

[Explanation of symbols]

1 ... Blower fan, 2 ... Blower duct, 2a ...
Stop fingers, 2b groove, 3 shielding plate, 4 rotating means, 4a rotating center axis, 4b
..Knurling part, 4c ... worm wheel part, 5
... Airflow detecting means, 6 ... Detection controller, 7 ... D
C motor, 8 output shaft, 20 drum unit, 21 photoconductor drum, 22 charger, 23
... Br developing device, 23a ... Br developing sleeve, 2
3b ... Br developing paddle, 23c ... Br toner density sensor, 24 ... Y developing device, 24a ... Y developing sleeve, 24b ... Y developing paddle, 24c ... Y toner density sensor 25 ... M developing device, 25a ... M
Developing sleeve, 25b ... M developing paddle, 25c ...
M toner density sensor, 26 ... C developing device, 26a
..C developing sleeve, 26b ... C developing paddle, 26
c: C toner density sensor, 27: housing, 31
..Fans, 32.
..Vertical shield plates.

Continuation of front page (56) References JP-A-6-194935 (JP, A) JP-A-3-263060 (JP, A) JP-A-6-208273 (JP, A) JP-A-6-130771 (JP) JP-A-5-188488 (JP, A) JP-A-2-310571 (JP, A) JP-A-4-326922 (JP, A) JP-A-63-296064 (JP, A) JP-A-63-296064 JP-A-5-27488 (JP, A) JP-A-3-47561 (JP, U) JP-A-2-127455 (JP, U) JP-A-60-73045 (JP, A) U) Japanese Utility Model Showa 56-152245 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 21/00 530-540 G03G 15/00 550 G03G 21/20

Claims (3)

(57) [Claims] 1. A ventilation device provided for discharging heat and discharge products generated inside an image forming apparatus to the outside of an apparatus, wherein an air flow is generated to discharge heat and discharge products to the outside of the apparatus. A blower fan, a blower duct arranged with the blower fan interposed therebetween and communicating between the inside and the outside of the device, two or more shield plates provided alternately opposite to the inner wall of the blower duct, and the inner wall of the blower duct. Rotating means for rotatably supporting the base end of each shielding plate to change the height of the shielding plate protruding into the air passage, wherein the shielding plate has a maximum projecting height A ventilating device, wherein a space is formed between the inner wall of the opposed ventilation duct and the end portions of the shielding plates overlap with each other when viewed from the ventilation direction. 2. The ventilating device according to claim 1, wherein the rotating means has a minimum height of the shielding plate so that an air flow is maximized while the image forming apparatus is performing image formation. The air vent is configured to rotate to a position where the height of the shielding plate is maximized so as to minimize the air flow during standby when image formation is not being performed. apparatus. 3. The ventilation device according to claim 1, further comprising an air flow detecting means for detecting an air flow rate in the air duct or in a side path directly connected to the air duct, wherein a detection value of the air flow detecting means is provided. A ventilation device characterized in that the height of the shielding plate is changed by turning the turning means in accordance with the following.