JPH06194935A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent exhaust air from a fixing unit from being supplied to a corona discharger and to prevent foreign matter from sticking to a discharge wire by providing a means for shutting off the supply of air to the corona discharger. CONSTITUTION:Even in a stand-by period, outside air is supplied from a fan 16 via an air supply duct 14 in order to cool an image processing substrate 11. At that time, the air supply duct 14 through which fresh outside air is supplied to a primary electrifier 3 is closed by a shutter plate 18, so that outside air is not supplied to the primary electrifier 3. When a copy button is operated by a user, a high voltage is applied to the corona discharge wire 3a of the primary electrifier 3. When voltage application is detected by a voltage application detecting circuit, the detection signal is outputted to a shutter plate opening/ closing circuit, and a solenoid 19 is driven to open the shutter plate 18. Consequently, the fresh outside air is supplied, and sticking of foreign matter to the corona discharge wire 3b is prevented.

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 provided with an image forming section and a fixing section using a corona discharger, and more particularly, to an image forming apparatus capable of preventing the corona discharge line of the corona discharger from being contaminated. It relates to the device.

[0002]

2. Description of the Related Art Conventionally, in the above-mentioned image forming apparatus, in order to primarily charge the photosensitive drum, transfer the toner image formed on the photosensitive drum to a recording sheet, and further separate it, a scorotron, a corotron, or the like is used. Corona discharger is used.

By the way, this image forming apparatus is constructed so as to prevent foreign matter from adhering to the corona discharge line of the corona discharger such as the scorotron or corotron.

That is, in the discharge line of the corona discharger of the above-mentioned image forming apparatus, dust from the environment, the developer used in the developing device, paper dust generated from the recording sheet, smoke molecules of cigarettes, and a fixing device are used. The vapor of the used silicone oil, the silicon gas generated from the silicon rubber material used in the device, etc. adheres or deposits.

As described above, if dust or a foreign material such as a developer adheres to the discharge line of the corona discharger, abnormal discharge occurs in the discharge line, so that it is impossible to form an image with good image quality.

Therefore, in the conventional image forming apparatus, in order to remove foreign matters such as dust, developer or vapor of silicon oil from the atmosphere inside the apparatus, an exhaust device forcibly exhausting the air inside the image forming apparatus to the outside. A filter is attached to the filter, and the filter is configured to adsorb, decompose, and remove foreign matter such as dust, developer, or vapor of silicon oil.

[0007]

However, the above-mentioned prior art has the following problems. That is, in the case of the above-described conventional image forming apparatus, there is a limit to removing foreign matters such as dust, developer, vapor of silicon oil, etc. from the atmosphere in the image forming apparatus only by the exhaust device, and the density of the filter is limited. There is a problem that if the height is made higher or the thickness is made thicker, the load on the fan for forced exhaust becomes larger and the fan becomes larger.

As described above, in the conventional image forming apparatus, it was extremely difficult to take measures to prevent the discharge line of the corona discharger from being contaminated. In addition to this, there is always a demand for small space, cost saving, low power consumption, low noise, and the like in office equipment such as copying machines, and it is necessary to satisfy the requirements in this respect.

Then, as a technique capable of solving such a problem, for example, there is one disclosed in Japanese Patent Application Laid-Open No. 1-128073. This Japanese Patent Laid-Open No. 1-128073
The image forming apparatus disclosed in Japanese Patent Publication includes an image forming unit that forms a toner image on a recording sheet by an electrophotographic process using a corona discharge device, and a fixing unit that fixes the toner image on the recording sheet. Image forming apparatus,
A shielding unit that blocks the flow of the atmosphere between the image forming unit and the fixing unit, an exhaust unit that forcibly discharges the evaporated material generated from the fixing unit to the outside of the apparatus, and a detection unit that detects the heating state of the fixing unit. And is configured to operate the exhaust means in accordance with the detected heating state of the fixing unit.

Further, in order to solve the above-mentioned problems, by supplying fresh outside air taken in from the outside of the image forming apparatus from the back surface of the corona discharger, foreign matter is attached to the discharge line of the corona discharger. It is also possible to surely prevent.

However, this case has the following problems. That is, in the case of the image forming apparatus according to the former proposal, the evaporation material generated from the fixing unit reaches the image forming unit by the shielding unit that blocks the circulation of the atmosphere between the image forming unit and the fixing unit. However, there is a problem that it is not possible to prevent dust, developer and the like from adhering to the corona discharger from the atmosphere in the image forming apparatus, which is insufficient.

Further, in the case of the image forming apparatus according to the former proposal, as in the latter apparatus, fresh outside air taken in from the outside of the image forming apparatus is supplied from the rear surface of the corona discharger, so that the corona discharger is supplied. If it is configured to reliably prevent foreign matter from adhering to the discharge line of the discharger, the exhaust air discharged from the fixing unit, which is shielded by the shielding unit from the image forming unit, to the outside of the apparatus again creates fresh outside air. There is also a problem that it is sucked into the inside of the device through an intake port for taking in and adheres to the discharge wire of the corona discharger.

On the other hand, the latter device has the following problems. That is, even in such an image forming apparatus, small space, cost saving, low power consumption, low noise, etc. are required. This is also required in terms of air control in the image forming apparatus, and has been realized by dividing the duct or the like into a plurality of systems with one fan or blower.

However, an image forming apparatus such as a digital copying machine requires an image processing electronic substrate for processing the read image, and an air cooling means is also required to cool the electronic substrate. Further, since the electronic board must be cooled during the copy standby, a system that constantly takes in outside air is also required.

Therefore, a system that constantly takes in outside air to cool the electronic substrate and a system that takes in fresh outside air to supply fresh air from the back surface of the corona discharger should be combined into one. Being configured is done.

However, in the case of the device of the latter proposal configured as described above, since the cooling fan is always operating because of the necessity of cooling the electronic substrate even during standby, the same intake system is used. The outside air is always supplied to the corona discharger composed of. Moreover, because of the small space required for the image forming apparatus, the exhaust port 10 of the fixing device is used.
0 and the inlet 101 for the cooling and charging device may be close to each other as shown in FIG. 9 and are provided at least on the same back side, so that the exhaust air from the fixing device is the intake air for the cooling and charging device. It is said that the air that is sucked in again from the mouth 101 and exhausted from the fixing device including the vapor of silicon oil is supplied to the corona charger even during the standby, and the vapor of the silicon oil adheres to and deposits on the discharge line of the corona charger. I had a problem.

Therefore, the present invention has been made to solve the above-mentioned problems of the prior art, and its object is to provide an example of cooling an electronic substrate and a system for supplying outside air to a corona discharger. Even if it is, prevent exhaust from the fuser as much as possible to be supplied to the corona discharger,
An object of the present invention is to provide an image forming apparatus capable of effectively preventing foreign matter from adhering to the discharge line of a corona discharger.

[0018]

The above-mentioned technical problems are as follows.
By supplying air outside the device to the corona discharger, it is possible to prevent foreign matter from adhering to the discharge line of the corona discharger.
In an image forming apparatus capable of discharging the air in the apparatus to the outside for cooling or exhaust heat, by providing air supply cutoff means for cutting off the supply of air to the corona discharger during standby of the image forming operation. To be achieved.

[0019]

According to the present invention, the air supply cutoff means cuts off the supply of air to the corona discharger during the standby of the image forming operation, so that the outside of the apparatus can be cooled or exhausted during the standby of the image forming operation. The air discharged to the corona discharger is prevented from being taken in from the supply system for supplying the air outside the apparatus to the corona discharger and supplied to the corona discharger.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to illustrated embodiments.

FIG. 2 shows a digital copying machine as an embodiment of the image forming apparatus according to the present invention.

In FIG. 1, reference numeral 1 denotes a main body of a digital copying machine. Inside the main body 1 of the copying machine, a photosensitive drum 2 for copying an image of an original document and a periphery of the photosensitive drum 2 are provided. Primary charger 3 and image exposure unit 4 provided in the
A developing device 5, a transfer charging device 6, a separation charging device 7, and a fixing device 8 for fixing a toner image on the transfer paper separated from the photosensitive drum 2 are housed. This fixing device 8
An original cooling fan (not shown) is provided, and the exhaust air of the cooling fan is exhausted to the outside from an exhaust port 10 formed in a casing 9 on the back surface of the copying machine body as shown in FIG. It is like this.

As shown in FIG. 4, a corona discharger such as a primary charger 3 for uniformly charging the surface of the photosensitive drum 2 is provided inside the main body 1 of the copying machine. Further, inside the copying machine main body 1, an image processing board 11 for processing an image of a document read by an image reading device (not shown) is provided on the back side thereof, and a louver 12 formed on a casing 9 on the back surface. It is arranged so as to face the opening 13.

In addition, inside the copying machine main body 1, FIG.
As shown in, the primary charger 3 as a corona discharger,
An air supply duct 14 is provided to prevent fresh air from supplying air from the back side thereof and to prevent foreign matter such as dust, developer or vapor of silicon oil from adhering to the corona discharge wire 3a of the primary charger 3. ing.

The tip of the air supply duct 14 is connected to an opening 15 formed on the back surface of the discharge shield 3b of the primary charger 3. Further, a fan 16 for taking in fresh air outside the machine is connected to the base end of the air supply duct. The fan 16 is adapted to take in fresh outside air from an intake port 17 formed in a casing on the back surface of the copying machine body. As shown in FIG. 3, the intake port 17 is formed in the vicinity of the exhaust port 10 for exhausting the exhaust gas from the fixing device 8 in order to save space in the apparatus. In the figure, F indicates a filter.

Further, the air supply duct 14 connected to the fan 16 is branched into two, and faces the opening 13 having the louver 12 formed in the casing 9 on the rear surface of the copying machine main body. Fresh external air is also supplied to the image processing board 11 provided, and the image processing board 11 is
Is designed to be cooled. Since the image processing board must be cooled even during copy standby, the outside air is constantly supplied by the fan 16. The fan may be configured to detect the temperature inside the machine and rotate during standby.

By the way, in this embodiment, among the air supply ducts 14, as shown in FIG. 1, in the middle of the air supply duct 14 for supplying fresh outside air from the back side of the primary charger 3. A shutter plate 18 is provided which can open and close the air supply duct 14 to shut off the air supply. This shutter plate 18 is a solenoid 1
It is movable up and down by an actuator such as 9 and is configured to open and close the air supply duct 14 at a predetermined timing.

As shown in FIG. 5, the solenoid 19 is connected to a shutter plate opening / closing circuit 20. The shutter plate opening / closing circuit 20 applies a high voltage to the corona discharge line 3a of the primary charger 3. It is connected to the voltage application detection circuit 21 for detecting.

With the above structure, in the image forming apparatus according to this embodiment, foreign matter is prevented from adhering to the corona discharge line of the corona discharger as follows. That is, in the digital copying machine, when the power is turned on prior to the copying operation of the image of the original, the electronic board for controlling the copying operation, the image processing board 11 and the like are energized, and the fixing device 8 is heated to a predetermined temperature. It is preheated to prepare for the user's copy request.

Further, in the digital copying machine, even during standby, the outside air is supplied from the fan 16 through the air supply duct 14 in order to cool the image processing substrate 11. At that time, the air supply duct 14 for supplying fresh outside air to the primary charger 3 is closed by the shutter plate 18, so that the outside air is not supplied to the primary charger 3.

When a copy button (not shown) is operated by the user, the photosensitive drum 2 is driven to rotate, and the fixing roller of the fixing device 8 is driven to rotate, so that the corona discharge line 3a of the primary charging device 3 is raised. Voltage is applied,
The photoconductor drum 2 is uniformly charged by the primary charger 3, and the image copying operation is started by the subsequent image exposure operation and the like.

At this time, when the application of the high voltage to the corona discharge line 3a of the primary charger 3 is detected by the voltage application detection circuit 21 as shown in FIG. 6, the voltage application detection circuit 21 outputs a detection signal. Is output to the shutter plate opening / closing circuit 20, and the solenoid plate 19 is driven by the shutter plate opening / closing circuit 20 to open the shutter plate 18. Therefore, in synchronization with the corona discharge of the primary charger 3, as shown in FIG. 1, the shutter plate is opened, fresh outside air is supplied from the air supply duct 14 to the back side of the primary charger 3, and the primary charging is performed. Foreign matter is prevented from adhering to the corona discharge wire 3b of the container 3.

As described above, in the above embodiment, the air supply duct 14 for supplying the fresh outside air to the primary charger 3 is closed by the shutter plate 18 in the copy standby mode. Is configured so that outside air is not supplied thereto. Therefore, in response to a request for space saving of the apparatus, the intake port 17 of the air supply duct 14 for supplying fresh outside air to the primary charger 3 discharges exhaust air from the fixing device 8 as shown in FIG. Even when formed near the exhaust port 11, exhaust gas containing silicon oil or the like discharged from the fixing device 8 is again taken in from the intake port 17 during copy standby, and primary charging is performed via the air supply duct 14. It can be prevented from being supplied to the container 3. Therefore, it is possible to prevent the deterioration of the image quality of the copy image due to the abnormal discharge due to the adhesion and deposition of the silicone oil or the like on the primary charger 3.

7 and 8 show another embodiment of the shutter plate, in which the shutter plate 18 is divided into a plurality of small shutter plates.
The air supply duct 14 is opened and closed by rotating each shutter plate 18 by a solenoid or a motor (not shown).

[0035]

EFFECTS OF THE INVENTION The present invention has the above-described structure and operation, and exhausts air from the fixing device even if the cooling example of the electronic substrate and the outside air supply system to the corona discharger are common. It is possible to provide an image forming apparatus capable of preventing supply to the corona discharger as much as possible and effectively preventing foreign matter from adhering to the discharge line of the corona discharger.

[Brief description of drawings]

FIG. 1 is a perspective configuration diagram of a main part showing an embodiment of an image recording apparatus according to the present invention.

FIG. 2 is a configuration diagram showing an image forming apparatus.

FIG. 3 is a rear view showing the image forming apparatus.

FIG. 4 is a configuration diagram showing an intake system of the image forming apparatus.

FIG. 5 is a block diagram showing a control circuit.

FIG. 6 is a timing chart showing the operation of the control circuit.

FIG. 7 is a perspective configuration diagram showing another embodiment of the present invention.

FIG. 8 is a perspective configuration diagram showing another embodiment of the present invention.

FIG. 9 is a rear view showing a conventional image forming apparatus.

[Explanation of symbols]

11 image processing board, 14 air supply duct, 16
Fan, 18 shutter plate, 19 solenoid.

Claims (1)

[Claims] 1. The air outside the apparatus is supplied to the corona discharger to prevent foreign matter from adhering to the discharge line of the corona discharger, and the air inside the apparatus is discharged to the outside for cooling or exhaust heat. An image forming apparatus capable of being discharged, comprising an air supply cutoff means for cutting off the supply of air to the corona discharger during standby of an image forming operation.