JPS63265258A - Image forming device - Google Patents

Abstract

PURPOSE:To stabilize image quality by providing a 2nd aperture to the part of a shielding case except the aperture for electric discharge thereof and covering at least a part of the part of the inside wall of the shielding case where the wall faces a discharge electrode with an insulating member. CONSTITUTION:The 2nd aperture 33 is provided to the face of the shielding case 32 opposite to the aperture 32a for discharge facing a photosensitive drum 13, by which part of the air passing the inside of a device body 1 passes the 2nd aperture 33 through the aperture 32a for discharge. The air is, therefore, not stagnated in the case 32 and no adverse influences are given on a corona discharger 14 and the drum 13 by the air contaminated by a developer and ozone. Part of the inside wall of the case 32 is formed of the insulator, by which the discharge efficiency to the drum 13 is increased and the formation of the ozone is decreased. The image quality is thereby stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an improvement of an image forming apparatus such as a copying machine or a printer using an electrophotographic method.

(Prior Art) Conventionally, a corona discharge device as shown in FIG. 8 has been used in image forming apparatuses such as electronic copying machines and laser printers. As is well known, in order to charge the photoreceptor drum 60 as an image carrier, a charge wire 61 connected to a high-voltage power supply trap (not shown) is connected to a grounded U-shaped shield case 62. 0, which causes corona discharge from the charge wire 61 to the photoreceptor drum 60 and shield case 62. In general, image forming apparatuses are equipped with rungs as various light sources and heating elements such as a fixing device. The heat generated by these, the ozone generated by oxygen in the air due to corona radiation, and the contaminated air caused by powder developer scattered from the developing means, etc. are discharged out of the image forming apparatus main body. Evacuation means such as electric fans are provided.

(Problems to be Solved by the Invention) As mentioned above, image forming apparatuses such as electronic copying machines are provided with exhaust means, so air is constantly circulating within the apparatus body. Air stagnates inside the U-shaped shield case as shown in Figure 8.

Powder developer scattered from the developing means, etc. is carried by the circulating air, and due to the above-mentioned air stagnation, it adheres to the inner wall of the shield case and the outer periphery of the charge wire, causing non-uniform discharge behavior and abnormalities. This causes changes in discharge and discharge efficiency, and these causes abnormal image quality and shortens the life of the device.

In addition, ozone tends to cause chemical changes with the photoconductor formed as a photosensitive layer on the photosensitive drum, and light 4 [body tp]
It is undesirable for ozone to remain in the vicinity of the photoreceptor drum, as this will significantly reduce the properties and life of the photoreceptor drum. here,
Since the amount of ozone generated increases approximately in proportion to the amount of discharge from the corona discharge devices, by increasing the total number of corona discharge devices to the amount of discharge to the photoreceptor drum t'JtO (discharge efficiency), There is a need to reduce the emission of corona discharge devices and reduce the amount of ozone produced.

The present invention has been made for the above reasons, and it is an object of the present invention to provide an image forming apparatus that has a simple configuration, but is capable of stabilizing image quality and improving the life of the apparatus, and has improved reliability. It is said that

[Structure of the invention]

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a corona discharge electrode, a shield case having a discharge opening and a second opening around the corona discharge electrode, At least a part of the part of the shield case facing the corona discharge electrode accommodates the 85 insulating member, at least the gRMi holder and the charging means, and is removable from the main body of the image forming apparatus. It consists of two openings and a casing having an opening passing through it.

(Function) A part of the air flowing inside the device main body passes through the discharge opening provided in the shield case, the second opening and the charging opening, and is then charged inside the shield case. No stagnation occurs, so air contaminated with developer or ozone will not have an adverse effect on the corona discharger or photoreceptor drum trap.
By forming part of the inner wall of the shield case with an insulator, the discharge efficiency with respect to the photoreceptor drum is increased and the generation of ozone is reduced.

(Example) The present invention will be described below with reference to an example shown in the drawings. FIG. 5 shows the external appearance of an electronic copying machine as an image forming apparatus, in which a document table 2 is provided on the upper surface of the apparatus main body 1 so as to be movable in the direction of the arrow.

Further, a control panel 3 is provided on the front side of the apparatus body 1, and this control panel 3Kft copy button 4. Clear/Stock key - 5° Set number of sheets up key 6. Set number of sheets down key 7゜Density up key 8. A density control key 9 and a display section 10 are provided.

Further, a paper feed tray 11 is provided on one side of the apparatus main body 1, and a paper discharge tray 2 is provided on the other side.

As shown in FIG. 6, a photosensitive drum 13 serving as an image carrier is rotatably provided at the center of the main body 1 of the apparatus. The photosensitive drum 13 is made of an aluminum tube coated with an organic photoconductor (OPC) on the outer peripheral surface.

Along the same section of the photoreceptor drum 130, along the direction of its rotational force,
Corona release 1! A charger 14 as a device, an optical system 15. Developer 16. Transfer charger 17 and IJ
+ A printing device 18 is provided at the first stage, and among these, the photosensitive drum 13. The charger 14 and the cleaning device 18 are unitized into a cartridge 35 as a casing configured to be detachably attached to the main body 1 of the device.

In addition, a conveyance path 1 for conveying paper P as a transfer target, which is fed from a paper feed tray 11, is provided at the lower side of the main body l of the apparatus.
9 is provided. This conveyance path 19 trap includes a feed roller 20° in the direction of the conveyance force of the paper P, a mo-roller 21a, a registration row 221b, a transfer guide 22. Transfer charger 1
7. A conveyance roller 23a, a conveyance guide 23b, and a fixing device 24 are disposed in this order, and an exhaust 71 vent 36 for discharging heat and contaminated air within the apparatus main body 1 is also provided.

As shown in FIGS. 3 and 4, the cartridge 35 has a cleaning grade 4 fixed to a grade holder 40.
1, a cleaning device 18 consisting of a recovery grade 420 recovered developer accommodating section 43, a photosensitive drum 13, and a charger 14, and an exposure opening 38, a static elimination opening 39, and a charging A slit 33, which is the second opening of the shield case 32, is bored as an opening for the device main body IK.
Slide guides 44 and 45 are provided for loading and unloading.

As shown in FIG. 1, the charger 14 includes a charge wire 31 as a corona discharge electrode connected to a high-voltage power supply (not shown), and a charge wire 31 connected to a
- a grounded case 32 for shielding, a slit 33 as a second opening provided on the surface of the shield case 32 facing the discharge opening 32a facing the photoreceptor drum 13; It is composed of a glass film 34 and K as an insulating member attached to the inner wall surface.

The optical system 15 includes a fluorescent lamp 26 and an ultraviolet absorber 2
'29, reflector 30, and frame 28)
It is constituted by a static elimination filter 25 and K provided at 28aK.

When copying is to be performed, the original G is first set on the original table 2 and the paper P is set in the paper feed tray IIK, and then the copy button 4 is turned on. As a result, light from the fluorescent lamp 26 that has passed through the ultraviolet absorption filter 29 is irradiated onto the document, and as the document table 2 moves, the surface of the photoreceptor drum 13 is uniformly charged by the charger 14.

The reflected light from the original G is transmitted to the surface of the charged photoreceptor drum 13 through the convergent light transmitter 27, and is transmitted through the exposure opening 38.
through which an electrostatic latent image is formed. This electrostatic latent image is sent to the developing device 16 by the rotation of the photosensitive drum 13, and is developed with the developer supplied from the developing device 16. The developer image is transferred to the paper P fed from the paper feed tray 11 and sent between the photosensitive drum 13 and the transfer charger 17 via the transfer guide 22.
It is transferred by the action of This paper P is the photosensitive drum 1
Stripped from 3! After that, the fuser 2 is inserted through the guide 23.
4, where the image is fixed, and then the paper is ejected to the paper ejection tray 12.

- After the developer image has been transferred to the paper P, the developer remaining on the surface of the photoreceptor drum 13 is scraped off by the cleaning blade 41 of the cleaning device 18, and is further reflected by the reflector 30. The light from the fluorescent lamp 26 that has passed through the static elimination filter 25 is irradiated through the static elimination opening 39, and the electrostatic latent image is erased.

The developer scraped off by the cleaning grade 41 is recovered by a recovery grade 42 and stored in a recovered developer storage section 43 by a transport means (not shown).

The cartridge 35 is opened when the collected developer storage section 43 is filled with a certain amount of collected developer, or when the photosensitive drum 13 is filled with a certain amount of collected developer.
When the cartridge reaches the end of its lifespan, it is configured so that it can be removed from the main body 1 of the device and replaced with a new cartridge.

- The heat and contaminated air inside the sword and device body are removed by the exhaust fan 36.
The air is exhausted outside the device main body 1. By providing the slit 33 on one surface of the shield case 32, a part of the air flowing through the exhaust fan 36 passes through the inside of the shield case 32. The air contaminated by ozone, etc. generated by corona discharge flows out of the cartridge 35 without being stagnated in the ruby case 32, and is further exhausted to the outside of the device main body 1, so that the corona discharge is stabilized. Become something. FIG. 7 shows that depending on the amount of discharge to the photoreceptor drum 13,
In a constant environment with a room temperature of 20'C and a humidity of 50%,
It shows the change in the surface potential received by the photosensitive drum 13 with respect to the number of continuous copies. AM in the figure shows the change in the surface potential when the rolled case 32 according to the present invention is used, and line B in the figure shows the change in the surface potential when the rolled case 32 according to the present invention is used. This figure shows the change in surface potential when a conventional rolled case shoe 2 is used and a cartridge without slits is used. This graph also proves that the corona discharge is stable.

Furthermore, by attaching a glass film 34 such as a polyester film to a portion of the inner wall surface of the rolled case 32, the amount of discharge to the rolled case 32 is reduced, so the discharge efficiency to the photoreceptor drum 13 is increased. It becomes possible to reduce the amount of ozone generated.

In addition, in the above example, the obi! Although an example using an apparatus has been described, the present invention is not limited thereto, and can also be applied to a transfer apparatus using corona discharge or an image forming apparatus having a structure in which a static eliminator is housed in a cartridge.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to prevent deterioration of the discharge device and photoreceptor drum caused by contaminated air, and to stabilize the image quality, even though the present invention has the 'ff3J#l configuration). A simple image forming apparatus can be provided.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a sectional view showing the configuration of a corona discharge device according to the present invention, and FIG. 2 is a diagram showing the main part configuration of an electronic copying machine as an image forming apparatus according to the present invention. , Fig. 3 and Fig. 4) are configuration diagrams showing an example of a cartridge containing an image carrier and a corona discharge device, Fig. 3 is a 11+11 sectional view, Fig. 4 is an external perspective view, and Fig. 5. 6 is a side sectional view showing the inside of the electronic copying machine, FIG. 7 is a diagram showing changes in surface potential with respect to the number of continuous copies, and FIG. 8 is an example of a conventional corona discharge device. FIG. 1... Apparatus main body, 13... Photosensitive drum, 14...
・Electrostatic charger, 18...Cleaning device, 31
...Charge wire, 32...Nolded case, 3
3...Slit, 34...Glasstic film,
35...Cartridge, 36...Exhaust fan. Agent Patent Attorney Noriyuki Ken Yudo Yamashita - Figure 1 Figure 2 Figure 3 Figure 4 Brown Sinbin Collection Figure 7 Figure 8

Claims (2)

[Claims] (1) An image carrier, a charging device that uniformly charges the surface of the image carrier, an exposure device that irradiates light to form an electrostatic latent image on the image carrier, and the electrostatic latent image. a developing device that visualizes the image; a transfer device that transfers the developed image to a transfer target;
In the image forming apparatus, the charging means includes a cleaning means for cleaning the surface of the image carrier after passing through the transfer means, and a charge eliminating means for erasing the electrostatic latent image on the image carrier. an electrode, a shield case provided around the corona discharge electrode and having a discharge opening, a second opening provided in a portion of the shield case other than the discharge opening; An image forming apparatus comprising an insulating member that covers at least a portion of the portion facing the corona discharge electrode. (2) At least the image carrier and the charging means are housed in the same housing, and the housing is configured to be removable from the main body of the image forming apparatus and communicate with the second opening. An image forming apparatus according to claim 1, characterized in that it has a charging opening that is perforated.