JPH0234866A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent a photosensitive body from deteriorating by sucking air inside of the device and releasing air to outside, and controlling the amount of released air to vary according to a image forming mode. CONSTITUTION:A fan motor starts to rotate in a low speed at previously set level at the same time of turning on a main switch or after a fixed time passes and a fan 21 sucks and releases the air inside of a box 1. The specified image forming mode is judged to be a continuous mode or a independent mode. When the specified mode is the continuous mode, the fan motor starts to rotate in high speed. The fan 21 rotates in high speed, and sucks and releases the air inside of the box 1. At this time, since the amount of released air increases, rising temperature whole of the device can be controlled low. When the image forming mode is the independent mode, the fan motor rotates in intermediate speed. Thus, the deterioration of the surface of the photosensitive drum 6 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an image forming apparatus that forms an image on an image carrier by an image forming means having a corona discharger.

<Prior Art> Today, with the development of information processing technology, various copying devices or image forming devices have been developed and are in use. These image forming methods include a thermal recording method, a thermal transfer recording method, an impact recording method, and an electrophotographic method. Among these, electrophotographic methods are widely and generally used in copying apparatuses.

The electrophotographic image forming apparatus charges a drum-shaped photoreceptor, which serves as an image carrier, with a corona discharger, and then
The photoreceptor is exposed to light to form an electrostatic latent image, and the latent image is developed with toner and transferred to a recording material to form an image.

Ozone (
Corona products such as 0, ) and nitrogen oxides (NOx) are generated. If these concentrations are high, the surface of the photoreceptor will change due to ozone, NOx etc. will adhere to the photoreceptor, the surface resistance of the photoreceptor will decrease, and the charge on the photoreceptor will spread (1) and the image will be blurred. This causes image deterioration called flow.

In order to prevent this phenomenon, the air around the corona discharger is sucked and exhausted to the outside by a fan through a filter that decomposes, removes, and adsorbs corona products contained in the air.

However, with the miniaturization of the image forming apparatus, it has become difficult to exhaust the area around the corona discharger placed around the photoreceptor, and corona products that remain during continuous image formation and when the photoreceptor is stopped. This may lead to local deterioration of the photoreceptor.

Conventional image forming apparatuses deal with the above problem by increasing the exhaust capacity of the fan or by driving the fan for a long time after the photoreceptor has stopped.

<Problems to be Solved by the Invention> However, the corona discharge time, exhaust time, etc. are different between when images are formed continuously by the above-mentioned image forming apparatus and when images are formed one by one. When a ζ image is formed, the concentration of corona products around the photoreceptor tends to be higher, and the photoreceptor is more likely to deteriorate than when an image is formed one by one.

Therefore, when increasing the exhaust capacity of the fan in the above-mentioned countermeasure, if the exhaust volume by the fan is set on the premise of continuous image formation, the exhaust volume will be equal to the exhaust volume required when forming images one by one. It becomes more than the quantity. In order to secure the above-mentioned displacement, it is necessary to increase the rotation speed of the fan,
It is necessary to extend the operating time of the fan, which causes problems such as increased noise and increased power consumption.

Further, if the exhaust amount by the fan is set on the premise that images are formed one by one, the exhaust amount will be smaller than the exhaust amount required when forming images continuously. Because of this corona product when continuously forming images? There is a problem in that the temperature becomes high and the photoreceptor is likely to deteriorate.

Further, in the case where only the fan is driven after the photoreceptor is stopped in the above-mentioned countermeasure, there is a problem in that the fan generates noise for a long time.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that can secure an appropriate exhaust amount depending on the image forming mode such as continuous image forming or single image forming.

<Means for solving the problem> An image forming apparatus for solving the above problem is a corona radiation T
i. In an image forming apparatus that forms an image on an image carrier by an image forming means having a container, an exhaust means for sucking air inside the image forming apparatus and exhausting it to the outside; Accordingly, the exhaust system is configured to include a control means for changing the exhaust amount by the exhaust means.

Further, in the image forming apparatus, the exhaust means may be a fan, and the number of rotations of the fan may be changed to change the exhaust amount.

Further, in the image forming apparatus, the exhaust means may be composed of a plurality of fans, and the plurality of fans may be selectively driven to change the exhaust amount.

Furthermore, the image forming apparatus can be configured to change the amount of exhaust by changing the air passage formed between the corona discharger and the exhaust means.

According to the above means, corona products generated inside the image forming apparatus can be sucked in by the exhaust means and exhausted to the outside of the apparatus, and at this time, the control means controls the amount of exhaust by the exhaust means in the image forming mode. By controlling according to the image forming mode, it is possible to obtain the displacement amount corresponding to each image forming mode.

Further, when the exhaust means is constituted by a fan,
By changing the rotation speed of the fan, the displacement amount can be controlled.

Further, when the exhaust means is constituted by a plurality of fans, the exhaust amount can be controlled by selectively driving the plurality of fans.

Furthermore, by forming an air passage between the corona discharger and the exhaust means and changing the air passage, the amount of exhaust can be controlled.

<Example> Hereinafter, an example of an electrophotographic image forming WZ to which the above-mentioned means is applied will be described with reference to the drawings.

[First Embodiment] FIG. 1 is a cross-sectional explanatory diagram of an image forming apparatus, FIG. 2 is a block diagram, FIG. 3 is a flowchart, and FIGS. 4 and 5 are timing charts.

First, the configuration of an image forming apparatus will be explained with reference to FIG.

In the figure, a platen glass 2a and a platen cover 2b, which are configured to be reciprocally movable in the direction of arrow a by a driving means (not shown), are provided at the top of a housing 1 of the image forming apparatus. The original 3 placed on the upper surface of the platen glass 2a is irradiated by a lamp 4 provided inside the main body 1 via the slit Za while moving in the direction of the arrow a. The reflected light from the original 3 is irradiated onto a photosensitive drum 6, which serves as an image carrier, through a lens 5. The photosensitive drum 6 is uniformly charged by a primary charger 7 which is a corona discharger, and an electrostatic latent image is formed by irradiation with reflected light from the original 3. The electrostatic latent image is developed with toner 8a in the developing device 8 to form a toner image.

On the other hand, recording material 9 such as plain paper or plastic film
is supplied to the registration roller IO, and is conveyed to the transfer charger 1), which is a corona discharger, in synchronization with the leading edge of the latent image formed on the photosensitive drum 6 by the roller 10. The toner image is transferred onto the recording material 9. The recording material 9 on which the toner image has been transferred is separated from the photosensitive drum 6 by a separation charger 12 that is a corona discharger, and is conveyed along a conveyance guide 13 . and fuser 1
4, and is discharged to the outside of the apparatus by a discharge roller 15.

After the toner image is transferred to the recording material 9 , the photosensitive drum 6 has its charging history erased by a static eliminating charger 16 which is a corona discharger, and the toner remaining on the photosensitive drum 6 is removed by a cleaning device 17 .

The photosensitive drum 6, the charger 7. The developing device 8 and the cleaning device 17 are surrounded by a cover 18 .

The interior of the housing 1 is divided by a partition wall 19 into a chamber 1b containing an optical system and a chamber 1c containing a corona discharger and a recording material transport system, and an opening 19a serving as an air passage is provided at a predetermined position in the partition wall 19. It is formed. A filter 20 for decomposing, removing, and adsorbing corona products such as ozone and NOx generated by corona discharge is installed in the opening 19a. As the filter 20, it is possible to use a ceramic filter formed in a honeycomb lattice shape or a parallel lattice shape, an activated carbon filter, a metal catalyst filter such as manganese, titanium 5 aluminum, silicon, platinum, etc.

A fan 21 serving as an exhaust means is provided in the chamber 1b. The fan 21 is driven by a variable speed fan motor 34 such as a DC motor, and is configured to rotate at a predetermined rotation speed set according to the image forming mode according to a command from a control unit 31, which will be described later. There is.

Further, as the fan 21, it is possible to use a known sirocco fan, an axial fan, or the like. By driving the fan 21 by the fan motor 34, air with a high concentration of corona products in the chamber IC is sucked through the filter 20 and exhausted to the outside of the apparatus. In addition, the air with a low concentration of corona products in chamber lb is
The air is directly sucked into the fan 21 and exhausted to the outside of the device. The fan 21 not only exhausts air containing corona products, but also functions to exhaust heat from the power supply section, fixing device 14, etc. (not shown).

The top surface of the housing 1 includes a main switch for instructing to start and stop the operation of the apparatus, a continuous image forming mode (hereinafter referred to as continuous mode) instruction button, an individual image forming mode (hereinafter referred to as single mode) instruction button, etc. An operation panel 22 for operating the image forming apparatus is formed.

Next, the control system of the image forming apparatus will be explained using the block diagram shown in FIG.

As shown in the figure, this control system includes a CPU 31a such as a microprocessor, a ROM 31b that stores data such as the operation program of the image forming mW and the rotation speed of the fan 21 according to the image forming mode, and instruction data from the Ii control panel 22. The control tn unit 31. which is configured by M31c to R for temporarily storing . Operation panel 22. Interface 32.
Main motor 33. A fan motor 34, a driver 35 for driving each of the motors 33 and 34. Lamp 4. -Charger 7. Transfer charger 1). Separation charger 12.
Static electricity removal charge 2St6. It consists of a high voltage power supply 36 for applying high voltage to each of the chargers.

In the uI control system, an operation panel 22 sends an apparatus drive start signal, instruction data such as an image forming mode such as a continuous mode or a single mode, to the control unit 31 via an interface 32. A signal corresponding to the instruction data is sent from the control section 31 to the driver 35. Lamp 4. It is sent to a high-voltage power source, etc., and drives each drive unit to form an image.

Next, the image forming operation by the above-mentioned image forming device will be explained using the flowchart of FIG. 3 and the timing charts of FIGS. 4, 5, and 5. Incidentally, FIG. 4 is a timing chart for continuous mode, and FIG. 5 is a timing chart for single mode.

First, the operation of the image forming apparatus is started using the main switch of the L production panel 22, and the continuous mode or single mode of the image forming mode is selected, and the recording material 9 is supplied to the registration rollers 10. As shown in FIGS. 4 and 5, the fan motor 34 is activated when the main switch is turned ON (t+
), or after a certain period of time has passed, the fan 21 starts rotating at a preset level 1 at a low speed, and the fan 21 sucks and exhausts the air inside the housing 1. The rotation of the fan 21 at level 1 prevents the temperature inside the housing 1 from rising due to preheating of the fixing device 14 or the like. Next, it is determined whether the instructed image forming mode is a continuous mode or an independent mode, and if it is a continuous mode, the process proceeds to step S4, and if it is an independent mode, the process proceeds to step S9 (S 1-33).

When the instructed image forming mode is continuous mode, the control unit 3I issues a data card 9 for rotating the fan motor 34 at high speed level 3, as shown in FIG. The rotation speed of the motor 34 is set. And even if the predetermined preparation time has passed since tl! When this happens, the main motor 33 starts rotating, and the photosensitive drum 6 starts rotating.

At the same time as the main motor 33 starts rotating, or after a certain period of time has elapsed, the fan motor 34 starts rotating at a high speed of level 3, and the fan 21 rotates at high speed to suck air inside the housing 1 and exhaust it to the outside. At this time, the exhaust amount by the fan 21 is larger than the exhaust I at level 1.

After the main motor 33 starts rotating, it performs pre-rotation for a predetermined period of time, and then the primary charger 7, which is a corona discharger, is activated. Transfer charger 1). Separation charger 12. Static neutralization charger 16
A high voltage from the high-voltage electric current f136 is applied to the terminals, etc. The lamp 4 is also turned on, and at the same time the platen glass 2a and platen cover 2b holding the original 3 move in the direction of arrow a.
An image is formed on the photosensitive drum 6. Moreover, the recording material 9 is
It is conveyed in synchronization with the leading edge of the image formed on the photosensitive drum 6, and the image is transferred onto the recording material 9 (34 to S7).
.

Next, it is determined whether or not image formation has been completed, and if it is not yet, the process returns to step S5 to continue forming an image.0 If it is determined that image formation has been completed, each of the chargers 7
．． 1). 12. Cut off the application of high voltage to 16 (t,
)do. The main motor 33 is then rotated for a predetermined period of time, and when it reaches t, the main motor 33 is stopped. At this time, the fan motor 34 continues to rotate at level 3, and after a certain period of time has passed since the main motor 33 stopped rotating, 1. , and returns to level l low speed rotation. and fan motor 3
4 maintains level I low speed rotation until new image formation is instructed, and then stops when the main switch is turned off (h) (S8).

In step S3, if it is determined that the image forming mode is the single mode, the process proceeds to step S9,
As shown in FIG. 5, the control unit 31 reads data for rotating the fan motor 34 at level 2, which is medium speed rotation, and sets the rotation speed of the motor 34. Thereafter, an image is formed in the same manner as the image formation for the continuous mode (39 to 512).

Next, it is determined whether image formation has been completed, and if it has not been completed, the process returns to step S10, and if it has been completed, each charger 7.1). 12. Cut off the application of high voltage to 16 (L
4) The main motor 33 is rotated after a predetermined period of time (t), and then the main motor 33 is stopped. If a certain period of time has passed after the main motor 33 stopped, the fan motor 3
4 is returned from level 2 to level 1, and rotation at level 1 is maintained until a new image formation instruction is issued. When the main switch is turned off (tt), the fan motor 34 also stops rotating.

In this embodiment, the amount of exhaust ffl when rotating the fan motor 34 at level 1 is set to approximately 0. In? /1n, and when performing level 2 rotation, the exhaust air ■ is approximately 0.25n? /min, and the exhaust air volume when performing level 30 rotations was set as approximately 0.35 m/win.

As mentioned above, in this embodiment, when forming an image in continuous mode, the fan 21 is rotated at a high speed of level 3 to eliminate ozone and NOx generated by corona discharge.
The surface of the photosensitive drum 6 is deteriorated because the corona products such as . Never.

Furthermore, when forming an image in the single mode, the discharge time by the corona discharger is short, so the total amount of corona products generated is small. Therefore, even if corona products are gently separated from the periphery of the photosensitive drum 6 during image formation and during post-rotation, the surface of the photosensitive drum 6 will not deteriorate.

According to this embodiment, when the image forming mode is the continuous mode, the fan motor 34 is rotated at high speed to strongly suck corona products, thereby immediately separating them from the periphery of the photosensitive drum 6. can prevent surface deterioration. Furthermore, in this case, since the amount of exhaust gas increases, it is possible to suppress the rise in temperature of the entire device.

Furthermore, when the image forming mode is the single mode, by rotating the fan motor 34 at a medium speed, it is possible to prevent the surface of the photosensitive drum 6 from deteriorating, and the noise is also reduced compared to the case of the continuous mode. l71) In addition to being excellent in cooling performance, the power consumption of the fan motor 34 is low, resulting in energy savings.

The rotation of the fan motor 34 in the continuous mode is
Control may be performed as shown in the figure or FIG. 7.

That is, in FIG. 6, the fan motor 34 rotates at a medium speed of level 2 during the forward rotation (tz to L,) and the rear rotation (t4 to ts), and the amount of paddy that is corona discharged. ,~t
It performs level 3 high speed rotation during 4. Even if the rotation of the fan motor 34 is controlled in this manner, corona products around the photosensitive drum 6 can be sufficiently removed.

Also, in FIG. 7, the fan motor 34 is rotating forward (
h to ts), level 2 medium speed rotation is performed, and level 2 medium speed rotation is continued for a certain period of time even if corona discharge is started. Then, when the concentration of corona products around the photosensitive drum 6 reaches t, the rotation shifts to level 3 high speed rotation. Even in this case, the corona products around the photosensitive drum 6 can be sufficiently removed, and since the time for the fan motor 34 to rotate at high speed at level 3 is short, power consumption can be reduced and energy can be saved. can be achieved.

Further, in this embodiment, the rotation speed of the fan motor 34 is set to level 1 to level 3, and the rotation speed of the fan 21 is changed. It is also possible to configure three transmission mechanisms with different reduction ratios between them and change the rotation speed of the fan 21 selectively through these transmission mechanisms.

In this case, the transmission mechanism comprises, for example, three gear trains with different gear ratios each having an independent electromagnetic clutch, and by selectively controlling the 78 If clutch of each gear train, Rotation corresponding to the rotation can be transmitted to the fan 21.

Further, in this embodiment, the main motor 33 and the fan motor 34 are separate motors, and the fan 21 is rotated even when the image forming apparatus is on standby to prevent the fixing device 14 from increasing the temperature inside the apparatus. For example, in an image forming apparatus using a pressure fixing device or the like, there is no need to prevent temperature rise during standby.

In this case, it is possible to share the main motor and fan motor.

A timing chart in this case is shown in FIG.

That is, when continuous mode is instructed as the image forming mode, the fan rotates at medium speed of level 2 shown by solid line A, and when single mode is instructed, the fan rotates at level 2 shown by dashed line B. 1 low speed rotation.

Also, set the fan to the above level 1. Rotation at the level 2 can be achieved by forming a transmission mechanism that combines a known gear and clutch, or a belt with blades and a clutch.

[Second Embodiment] FIG. 9 is a cross-sectional explanatory diagram of the image forming apparatus of this embodiment.
Figure O is a block diagram of the control system, and Figures 1) and 12 are timing charts. In the drawings, the same parts and parts having the same functions as those in the previous embodiment are given the same reference numerals, and the explanation thereof will be omitted.

In the figure, the bottom surface of the chamber 1c formed in the housing 1,
Further, a second fan 41 is provided near the transfer charger 1). The second fan 41 is driven by a fan motor 44 shown in FIG. 1O.

A second filter 42 is mounted on a filter holder 43 opposite to the second fan 41 for decomposing, removing, and adsorbing corona products such as ozone and NOx.

The second fan 41 is configured to rotate in synchronization with the rotation of the main motor 33 when the image forming mode is continuous mode.

In the image forming apparatus of this embodiment, the driving timing of each fan 21, 41 in continuous mode is shown in Fig. 1). In the figure, the fan motor 34 rotates at a low speed of level 1 when the main switch is turned on, and shifts to medium speed rotation of the bell 2 at the same time as the main motor 33 starts rotating, or after a certain period of time has elapsed.

In synchronization with the start of rotation of the main motor 33, the second fan motor 44 starts to rotate, and the second fan 41 starts to rotate.

Since the second fan 41 is provided near the transfer charger 1), the second fan 41 can intensively suck in air with a high concentration of corona products around the photosensitive drum 6 and exhaust it to the outside of the apparatus. This makes it possible to prevent deterioration of the photosensitive drum 6. Further, since the second fan 41 is provided in the chamber 1c, residual heat of the fixing device 14 in the chamber 1c can be efficiently removed.
Therefore, the temperature rise inside the device can be suppressed to a low level.

In addition, when the image forming mode is the single mode, the first
As shown in FIG. 2, the second fan motor 44 is not driven during the image forming period.

As described above, in the image forming apparatus of this embodiment, the rotation of the fan motor 34 during the image forming period in the continuous mode stops at the medium speed rotation of level 2, and therefore, as the fan 21 rotates, It becomes possible to reduce the generated noise.

Also, filter 2042 corresponding to each fan 21.41
By providing this, the burden on each filter 20.42 is reduced and the life of the filter 20.42 can be extended.

In this embodiment, a second fan motor 44 is provided to drive the second fan 41, but this is similar to the main motor 33.
1 or between the fan motor 34 and the second fan 41,
A transmission mechanism may be formed using a clutch, a gear, a belt with blades, etc., and the rotation of the main motor 33 or fan motor 34 may be transmitted through the transmission mechanism when the continuous mode is instructed.

[Third Embodiment] FIGS. 13A and 13B are cross-sectional explanatory views of the image forming apparatus of this embodiment, and FIG. 14 is a block diagram of the control system.

In the drawings, the same parts and parts having the same functions as those in the previous embodiment are given the same reference numerals, and their explanations will be omitted.

In the figure, an air passage 51 is formed in the gap between the cover 18 and the partition wall 19. Further, air passages 18a and 18b having a sufficiently larger area than the air passage 51 are formed in the cover 18. The air passage 18a is connected to the partition wall 1
The air passage 18b is formed near the filter 20 attached to the filter 9, and the air passage 18b is formed at a position separated from the filter 20.

The air passage 18b is provided with a closing member 52 that swings about a shaft 52a to selectively open the air passage 18b and the air passage 51. The closing member 52 is driven by an opening/closing mechanism 53 such as a solenoid or a swing motor, and swings in the direction indicated by the arrow to open the air passage 18b and close the air passage 51 when the image forming mode is the continuous mode. When in the standalone mode, it is configured to swing in the direction of arrow C to open the air passage 51 and close the air passage 18b.

In this embodiment, when the image forming mode is the continuous mode, the closing member 52 swings about the shaft 52a in the direction indicated by the arrow as shown in FIG. 13(A), and the air 1) 1)
The passage 18b is opened and the air passage 51 is closed. Air with a high concentration of corona products generated by the primary charger 7 during image formation is sucked directly by the fan 21 from the air passages 18a and 18b formed in the cover 18.

In addition, when the image forming mode is the single mode, the first
As shown in FIG. 3 CB), the closing member 52 is swung in the direction of arrow C to close the air passage 18b and close the air passage 5.
1 is opened and the air with a corona product concentration generated in the primary charger 7 is transferred to the air i1! Fan 2 via l path 51
Aspirate by 1.

As described above, in this embodiment, the air passage 18b and the air passage 51 are selectively opened depending on the image forming mode to change the exhaust amount by the fan 21. As described above, the image forming apparatus of the present invention changes the number of rotations of the fan depending on the image forming mode.

By changing the number of driven fans or the area of the air passage inside the device, the exhaust amount can be controlled to an optimal amount. Therefore, corona products such as ozone and NOx generated by corona discharge can be efficiently exhausted, and deterioration of the image carrier can be prevented.

In addition, since the exhaust volume is controlled according to the image forming mode, the fan rotation speed does not increase more than necessary.
Therefore, it has features such as being able to reduce noise and power consumption.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional explanatory diagram of the image forming apparatus of the first embodiment, FIG. 2 is a block diagram, FIG. 3 is a flowchart, and FIGS.
8 is a timing chart, FIG. 9 is a cross-sectional explanatory diagram of the image forming apparatus of the second embodiment, FIG. 1O is a block diagram, FIG. 1) and FIG. 12 are timing charts, and FIG.
A) and (B) are cross-sectional explanatory views of the image forming apparatus of the third embodiment, and FIG. 14 is a professional view. ■ is the housing, 2a is the platen glass, 2b is the platen cover, 4 is the lamp, 5 is the lens, 6 is the photosensitive tram, 7 is the primary charger, 8 is the developer, 9 is the recording material, 1) is the transfer charger , 12 is a separation charger, 14 is a fixing device, 16 is a neutralizing charger, 17 is a cleaning device, 18 is a cover, 18a, 18
b is an air passage, 19 is a partition wall, 2042 ha filter, 2
I is a fan, 22 is an operation panel, 31 is a control unit, 31a
is a CPU, 31b is a ROM, 31c is a RAM, 32 is an interface, 33 is a main motor, 34 is a fan motor, 35 is a driver, 36 is a high voltage power supply, 41 is a second fan, 43 is a filter holder, 44 is a second fan Motor, 51 is an air passage, 52 is a closing member, 52a
is a shaft, and 53 is an opening/closing mechanism. Patent applicant Canon Co., Ltd.

Claims (4)

[Claims] (1) In an image forming apparatus that forms an image on an image carrier by an image forming means having a corona discharger, an exhaust means for sucking air inside the image forming apparatus and exhausting it to the outside; An image forming apparatus comprising: a control means for changing an exhaust amount by the exhaust means according to a forming mode. (2) The image forming apparatus according to claim (1), wherein the exhaust means is a fan, and the exhaust amount is changed by changing the number of revolutions of the fan. (3) The image forming apparatus according to claim (1), characterized in that the exhaust means is composed of a plurality of fans, and the plurality of fans are selectively driven to change the exhaust amount. image forming device. (4) In the image forming apparatus according to claim (1), the image forming apparatus is characterized in that the air passage formed between the corona discharger and the exhaust means is changed to change the exhaust amount. Device.