JPH01302369A - Image forming device - Google Patents

Abstract

PURPOSE:To eliminate a separation failure, and also, to realize a long service life of a destaticizing needle and to improve the durability of a body by providing a means for cleaning automatically the destaticizing needle of the body at the time of replacement. CONSTITUTION:At the time of drawing out a process cartridge 20 from a body along guide rails 24, 25, a photosensitive body shutter 3 rotates centering around pins 19, 21 and executes a link motion, covers an exposed part of a photosensitive drum 1, and in that case, a destaticizing needle cleaning brush 6 traverses so as to interfere with a destaticizing needle 7 and cleans the destaticizing needle 7. After the process cartridge 20 has been inserted, when the upper frame 12 is closed centering around a supporting point, the photosensitive body shutter 3 rotates centering around the pins 19, 21 and executes a link motion, the exposed part of the photosensitive drum 1 is opened and it is provided so as to be opposed to a transfer electrifier 4, and in that case, the destaticizing needle cleaning brush 6 cleans the destaticizing needle 7. In such a way, an effect of the destaticizing needle 7 for separating transfer paper which has adhered closely to the photosensitive body 1 can be maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to an image forming apparatus that transfers an image formed on a photoreceptor onto transfer paper.

"Prior Art" Conventionally, image forming apparatuses, except for the image processing section, paper feeding section, and fixing section, usually have a primary charger that places an electric charge on a photoconductor, and an exposure device that exposes an image onto the charged photoconductor. A development section that visualizes the electrostatic latent image formed on the photoreceptor by exposure, a transfer charger that transfers the developed image on the photoreceptor onto transfer paper, and a transfer residual agent on the photoreceptor. It consists of a cleaning section for removing charges, and a pre-exposure section for erasing charges on the photoreceptor.

The transfer paper is conveyed to the transfer unit in synchronization with the image developed on the photoconductor, and is brought into almost close contact with the photoconductor, and is exposed to light by charging the back side of the transfer paper with an electrical charge of opposite polarity to the developer and by pressing force. Transfer the image from the body to the transfer paper.

After the transfer process, there is a separation process to separate the photoreceptor from the transfer paper, and the transfer paper is normally charged with a polarity opposite to that of the transfer from the back side.

Particularly when the curvature of the photoconductor downstream of the transfer section is large, as is the case with small-sized image forming devices, the curvature of the transfer paper is stronger than the adhesion between the transfer paper and the photoconductor. However, for weak transfer paper such as thin paper or environments where separation is difficult, an electrode called a static elimination needle is provided, and a discharge is generated from its sharp tip to repel the transfer paper against the photoreceptor using electric force. This assists in curvature separation.

"Problem to be Solved by the Invention" In the conventional example described above, the static elimination needle discharges electricity in order to separate the transfer paper, and the transfer paper passes over the static elimination needle, but each time a small amount of electricity is generated. However, the paper dust accumulates, and dust and ionized particles in the atmosphere are attracted and adhere to the static elimination needle.

When tens of thousands of sheets of transfer paper pass through, the static elimination needle becomes contaminated due to the reasons mentioned above, deteriorates, impedance increases, and discharge capacity decreases. There was a drawback that separation was not necessary.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that can maintain the effect of a static elimination needle for separating a transfer sheet that is in close contact with a photoreceptor after transferring an image formed on the photoreceptor.

"Means for Solving the Problem" The present invention has a charge eliminating needle on the main body side for separating the transfer material that is in close contact with the photoreceptor after transferring the image formed on the photoreceptor to the transfer material. A process car that houses some units of the forming process and is removable from the main body) In an image forming apparatus equipped with an IJ screw, the process cartridge is equipped with a means to automatically clean the static elimination needle when replacing the process cartridge. This is an image forming apparatus.

"Embodiment" FIGS. 1 and 2 are longitudinal sectional views of an embodiment of the present invention. Around the photoreceptor drum 1, there are a primary charger 13, a developer 14,
A cleaning device 2 is provided and housed in a cartridge case 15. The cartridge case 15 has an opening in the portion where the photoconductor drum 1 faces the transfer charger 4 provided on the lower frame 16 of the main unit of the transfer section, and the opening is located at a position where it can be opened and closed by the photoconductor shutter B. The shutter 3 has two shutter arms 8, each of which has a shutter 6 rotatably attached to its tip with a pin 17, 18, and the base of each of the 8 degrees is pinned to the end plate of the cartridge case 15 (parallel to the plane of the paper in FIG. 1). It is supported by a double crank mechanism pivoted at 19°21. A flexible bristle-type static elimination needle cleaning brush 6 is attached to the shutter 3 in parallel to the axial direction of the photoreceptor drum 1. The cartridge case 15 has a photosensitive drum 1.
With respect to the rotational direction, a window 22 for irradiating pre-exposure light onto the front and rear positions of the -order charger 13, and a window 26 for introducing image light to be formed.
is provided. The process cartridge 20 configured as described above has a guide rail 24 provided on the upper frame 12.
25 from the direction perpendicular to the paper surface of FIG.
will be installed.

The photoreceptor shutter 3 is configured to close when the upper frame 12 is opened centering on the upper frame opening/closing fulcrum 11 which is pivotally connected to the lower frame 16, and to open when the upper frame 12 is closed. Although not shown, these are performed by mechanical means or electromagnetic means.

As shown in FIG. 1, the lower frame 16 includes a transfer guide 9 for introducing transfer paper fed from a paper feed section (not shown) into the transfer section;
A transfer charger 4 applies a charge of opposite polarity to the charge of the developer from the back of the transfer paper, and a charge remover applies charges of opposite polarity to the discharge polarity of the transfer charger 4 to the transfer paper to promote separation from the photoreceptor drum 1. A conveyor belt 10 for conveying the transfer paper separated from the needle 7 and the photoreceptor drum 1 is provided. The static eliminating needles 7 are embedded and arranged in parallel in the axial direction of the photosensitive drum 1 in a static eliminating needle block 5 made of an insulating material fixed to the transfer charger 4.

In FIG. 1, when the photoreceptor drum 1 rotates in the direction of the arrow shown in the figure, the surface of the photoreceptor drum 1 is uniformly charged by the primary charger 13, and the image light sent through the window 23 is condensed on the photoreceptor drum 1. A latent image is formed in the developing device 14, and a developer is applied to the developing device 14 to form a developed image.A sheet feeder (not shown) The developed image is transferred to the transfer paper that is fed from the transfer guide 9) at a timing taken from the photoreceptor drum 1, and is transferred by being given an electric charge of opposite polarity to the transfer charger 4 due to the curvature of the photoreceptor drum 1 and the static elimination seal 7. The paper is separated from the photosensitive drum 1, sent to a fixing device (not shown) by a conveyor belt 10, fixed thereon, and discharged outside the machine.

On the other hand, the photoreceptor drum 1 further rotates and the cleaning device 2
The remaining toner is removed, and the previous history is erased by the pre-exposure light sent from the window 22, in preparation for the next image formation.

When the image forming process is repeated, paper powder, dust, ionized fine particles, etc. are attracted and adhere to the static elimination needle 7. However, when the developer in the developing device 14 runs out, the process cartridge 20 can be replaced with a new one or replenished with developer.The process cartridge 20 is detached from the main body. Therefore, when pulling out the process cartridge 20 from the main body along the guide rails 24 and 25, first open the upper frame 12 around the upper frame opening/closing fulcrum 11 to protect the exposed portion of the photoreceptor drum 1 from external light. The photoreceptor shutter 3 rotates around pins 19 and 21 and performs a linking motion to cover the exposed portion of the photoreceptor drum 1. At this time, the static eliminating needle cleaning brush 6 cleans the horizontally crossing static eliminating needle 7 by interfering with the static eliminating needle 7. After inserting the process cartridge 20 into the main body along the guide rails 24 and 25, when the upper frame 12 is closed around the fulcrum, the photoreceptor shutter 3 rotates around the bin 19 and performs a linking movement, and the photoreceptor drum The exposed portion of 1 is opened and placed opposite to the transfer charger 4. At this time, the static elimination needle cleaning brush 6 cleans the static elimination needle 7. As a result, paper dust, dust, and ionized fine particles adhering to the static elimination needle 7 are removed, and the static elimination ability is restored.

"Experimental example" The shape is as shown in Figure 6, and the thickness is 0. In length is 225 In, which is larger than the maximum paper size (letter size)
The height of the serrated uneven portion at the upper end is 2 mm, and the diameter of the photoreceptor drum 1 is 3011 m using a static eliminating needle 7 made of stainless steel and nickel plated.

- The photoreceptor drum 1 is negatively charged by the charger 13,
A positively charged developer is supplied, the transfer charger 4 is of a corotron type, and the original image on the photoreceptor drum 1 is negatively charged, and the static eliminating needle 7 is applied with a bias of ±5.5 K"i' and 110 μA. The photoconductor cleaning brush 6 has a length of 225n, which is the same length as the static elimination needle 7, a height of about 7m, a width of 5fl in the paper passing direction, and is densely planted. The material used was pig hair.

Figure 4 shows the experimental results. As a comparative example, when a durability test was conducted on 20,000 sheets of 6497 m'' A4 size paper with the above-mentioned configuration excluding the cleaning brush 6 from FIGS. 1 and 2, the static elimination needle The current flowing through 7 is initially 110μ
A had decreased to 40 μA, and poor separation occurred when the paper was passed through a cross-grained paper at 52 r/m2. The reason why the electric current decreased and the discharge became weak is that paper powder accumulated around the static elimination needle 7 and that ionic compounds were attached to the sharp tip of the static elimination needle 7. In this state, when the static eliminating needle 7 was brushed, the paper powder was removed, but the ionic compound could not be removed. The current is 60μ as shown in the dot in Figure 4.
Although it recovered to A and no separation failure occurred even with 52y/m2 paper, when the durability test was continued as before, the static elimination needle failed after passing an additional 10,000 sheets as shown at point C in Figure 4. The current flowing through No. 7 decreased to 20 μA, and even after brushing, the degree of recovery continued to decrease. This is because strongly attached ionic compounds cannot be easily removed.

In the present invention, as mentioned above, since the process cartridge 20 in which the photoreceptor, the developing device, the secondary charging device, the cleaning device, and the cleaning device are integrated is used, the developer is depleted after about 6,000 yen.
The process cartridge 20 is replaced by opening and closing the upper frame 12 for each process cartridge.

Therefore, when we conducted the same experiment as the comparative example using the configuration of the embodiment of the present invention, we found that no separation failure occurred until 50,000 sheets were printed because the static elimination needle was cleaned twice when the cartridge was replaced once every 6,000 sheets. As shown in the figure, the decrease in the current flowing through the static eliminating needle 7 was also alleviated. Even considering actual usage conditions, the upper frame 12 will be opened and closed more frequently due to paper jams caused by causes other than poor separation or the use of background-colored cartridges, so the cleaning effect will be more effective. As a result, it is thought that the occurrence of poor separation will no longer occur.

In the embodiment, a brush is used as a means for cleaning the static elimination needle, but a rubber wiper, felt, etc. may also be used.

〔Effect of the invention〕

As explained above, periodically replace the process cartridge containing the photoreceptor and other components ii! By providing a means to automatically clean the static elimination needle on the main body side when replacing the JgI forming device, it is possible to eliminate separation defects and extend the life of the static elimination needle, that is, improve the durability of the main body. .

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a first embodiment of the warp forming device of the present invention, and FIG. 2 is a vertical cross-sectional view showing a state in which the upper frame of FIG. 1 is slightly opened.
FIG. 3 is a front view of the static eliminating needle, and FIG. 4 is a diagram for explaining the present invention in detail. 1. Photoreceptor 3e. Shutter 5.h Static elimination needle block 6. Static elimination needle brush 7. Static elimination needle. Figure 1 What Figure 2

Claims (1)

[Claims] 1. The main body has a static elimination needle for separating the transfer material that adheres to the photoreceptor after transferring the image formed on the photoreceptor to the transfer material. An image forming apparatus equipped with a removable process cartridge, characterized in that the process cartridge is provided with means for automatically cleaning a static elimination needle when replacing the process cartridge.