JPH03208070A - Residual toner fall-off preventing device in electrostatic type electrophotographic device - Google Patents

Abstract

PURPOSE:To decrease the quantity of a toner peeled off by a peeling scraper or the quantity of the toner falling down from the peeling scraper and to prevent the contamination of transfer paper by providing an insulator on the part corresponding to the peeling scraper of a transfer charger case. CONSTITUTION:An insulator 16 is provided on a partition plate (a) of the part corresponding to a pair of peeling scrapers 13 which come into contact with and are separated from a photosensitive drum 1. In an area where the insulator 16 is present thereon, the impedance to a discharge current is increased, a discharge current to a transfer charger case 9a is decreased, and a discharge current to the drum 1 is increased. Therefore, the efficiency for transferring a toner on the drum 1 onto transfer paper is enhanced, and the residual toner quantity on the drum 1 of the area where the insulator 16 is present thereon is decreased. In such a manner, the quantity stuck to the scraper 13 is decreased, the quantity of the toner peeled off by the scraper 13 or the quantity of the toner dropping down from the scraper 13 is decreased and the contamination of transfer paper can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention is an electrostatic electrophotographic apparatus such as a copying machine or a printer, in which a peeling claw is used to mechanically peel transfer paper from a photoreceptor drum. The present invention relates to a technique for preventing residual toner on a photoreceptor drum from falling onto transfer paper.

<Prior Art> The copying process of a conventional general copying machine will be explained based on FIG.

■ Due to the negative corona discharge of the main charger 2, the entire surface of the photosensitive drum 1 is uniformly charged with a negative H. Charge r1. Further, the surface potential of the photoreceptor drum 1 is maintained at a potential equal to the drift voltage controlled by the screen glyph 3.

(2) Exposure An optical image of the original is projected onto the surface of the photoreceptor drum l via the optical system 4 using a copy lamp (not shown).

In the area exposed to light (bright area of the document), the photoreceptor drum 1
Photosensitivity 1 (OPC layer: organic photoconductor)
Because the electrical resistance value of decreases and removes the negative charge,
An electrostatic latent image is formed on the surface of the photosensitive drum 1.

■ By applying a negative bias voltage to the rotating magnetic roller 6 in the developing unit 5, the toner T is
is positively charged due to friction with the rotating carrier, and by adsorbing this toner T to the negative charge on the photoreceptor drum 1, the electrostatic latent image on the surface of the photoreceptor drum 1 can be covered with the toner T. Make it into a visual image (two-component magnetic brush development).

■ With the surface of the transfer paper 8 guided by the transfer paper guide 7 aligned with the surface of the photoreceptor drum 1, by negatively charging the back surface of the transfer paper 8 by negative corona discharge of the transfer charger 9. , the toner T on the surface of the photoreceptor drum 1 is transferred to the transfer paper 8, and the visible image on the photoreceptor drum 1 is transferred to the transfer paper 8. This situation is shown in FIG. 9a is a transfer charger case, 9b is a transfer charger wire, and 10 is a high voltage unit. The transfer charger 9 is configured to start discharging at the timing when the leading end of the transfer pad 8 passes.

■ Electrostatic release After transfer, both the transfer paper 8 and the photoreceptor drum 1 are negatively charged, but the negative potential of the transfer sheet 8 is more negative than the photoreceptor drum 1.
Since the negative potential is higher than the negative potential of , an electrostatic attraction force is exerted between the photosensitive drum 1 and the transfer paper 8.

Therefore, by applying alternating current corona discharge to the transfer paper 8 by the peeling charger 11, the negative potential of the transfer plate 8 is lowered to the same potential as the negative potential of the photoreceptor drum 1. As a result, the electrostatic attraction force disappears, and the transfer sheet 8 is peeled off from the photoreceptor drum 1 due to the stiffness of the transfer sheet 8.

The situation is shown in Figure 8. 11a is an IJIM charger case, llb is a peelable charger wire, and 12 is a high voltage unit. The peeling charger 11 is configured to start discharging at the timing when the leading edge of the transfer paper 8 passes. ■ Mechanical Peeling When the peeling charger 11 fails to properly peel off the transfer paper 8, the transfer paper 8 moves together with the photosensitive drum 1 toward the peeling claw l3, but the tip of the transfer paper 8 does not touch the peeling claw. 13, a solenoid (not shown) is energized and the pair of left and right peeling claws 13 come into sliding contact with the surface of the photoreceptor drum 1, and the transfer nail 8 is reliably peeled off from the photoreceptor drum 1 by the peeling claws l3. .

(2) Cleaning The toner T remaining on the photosensitive drum 1 is scraped off and collected by the cleaning blade l4.

(2) Static Elimination Residual charges on the photosensitive drum 1 are erased by lowering the electrical resistance value of the surface of the photosensitive drum 1 using the irradiated light from the static eliminating lamp 15.

Problems to be Solved by the Invention> In the transfer step (see FIG. 7) of (1) above, not all of the toner T on the surface of the photosensitive drum 1 is transferred to the transfer plate 8, but only 15 to 20% of the toner T is transferred to the transfer plate 8. A certain amount of toner T remains on the photoreceptor drum 1.

When the transfer paper 8 is peeled off by mechanical peeling instead of electrostatic peeling M (see FIG. 8), the peeling claw 13 that peels off the transfer paper 8 from the photosensitive drum 1 is attached to the photosensitive drum 1.
Since the residual toner T comes into sliding contact with the surface of the peeling claw 13, the residual toner T adheres to the tip of the peeling claw 13 or is peeled off by the peeling claw 13.

The peeled off toner T falls onto the surface of the transfer paper 8 currently being processed and stains the transfer paper 8. The adhered toner T is also eventually peeled off by the tip of the transfer ring 8 to be processed next, staining the surface of the transfer ring 8.

The reason why the residual toner T on the photosensitive drum 1 is peeled off at the tip of the peeling claw l3 is not only due to the sliding contact of the peeling claw, but also because the negative potential of the photosensitive drum 1 is lowered by the discharge of the peeling charger 11. , the residual toner T is transferred to the photoreceptor drum 1.
Another possibility is that the suction power that holds the material in place decreases. In other words, since the adhesion force of the photoreceptor drum 1 to the residual toner T is reduced, the residual toner T is easily peeled off by the peeling claw 13.

Therefore, as a measure to prevent the toner T peeled off by the peeling claw l3 and the toner T attached to the peeling claw l3 from falling onto the transfer paper 8, a tray for receiving toner is provided directly below the peeling claw 13. It is possible that

However, if the tray is provided, it compresses the installation space for the lower conveyor belt l6, and the position of the starting end of the conveyor belt 16 moves backward, which adversely affects the conveyance accuracy. Furthermore, the provision of trays increases costs.

The present invention has been devised in view of the above circumstances, and electrically suppresses toner on a photosensitive drum from being peeled off by a peeling claw or adhering to the peeling claw without providing a tray. In particular, the purpose is to prevent staining of the transfer paper.

<Means for Solving the Problems> In order to achieve the above object, the present invention has the following configuration.

[i] The residual toner fall prevention device in the first electrostatic electrophotographic apparatus of the present invention forms an electrostatic latent image on the surface of a charged photoreceptor drum by irradiating light, and prevents toner from falling on the surface of the photoreceptor drum. The electrostatic latent image is developed into a visible image by attaching the toner, and the toner forming the visible image is transferred to the transfer paper along the surface of the photoreceptor drum by the discharge of the transfer charger, and the toner forming the visible image is transferred to the transfer paper along the surface of the photoreceptor drum. The transfer paper is electrostatically peeled from the photoreceptor drum by lowering the potential of the photoreceptor drum by electric discharge, and the transfer paper not peeled off by the peeling charger is mechanically peeled from the photoreceptor drum by a peeling claw. In the electrostatic electrophotographic apparatus, an insulator is attached to at least a portion of the transfer charger case of the transfer charger that corresponds to the peeling claw.

[11] The second residual toner fall prevention device in an electrostatic electrophotographic apparatus of the present invention is an electrostatic electrophotographic apparatus similar to the above, in which a peel charger wire in the peel charger faces the photoreceptor drum. Among the parts, at least a part corresponding to the peeling claw is coated with an insulator.

<Function> [i] According to the first residual toner fall prevention device of the present invention, by attaching an insulator to the transfer charger case, the electrical resistance of the transfer charger case is increased at a portion corresponding to the peeling claw. As a result, the discharge current flowing to the transfer charger case decreases, and as a result, the discharge current flowing to the photoconductor drum increases, and the amount of toner transferred from the photoconductor drum to the transfer paper increases in the area corresponding to the peeling claw. , the amount of residual toner on the photoreceptor drum is reduced at a location corresponding to the peeling claw.

[l1] According to the second residual toner drop prevention device of the present invention, by covering the peeling charger wire in the peeling charger with an insulator, the discharge between the peeling charger wire and the photoreceptor drum is prevented at a portion corresponding to the peeling claw. Since the tt flow is reduced and the potential of the photoreceptor drum is prevented from decreasing, the adsorption power of the residual toner on the photoreceptor drum is prevented from decreasing.

<Example> Hereinafter, an example of the present invention will be described in detail based on the drawings.

The first embodiment of Hoshigami Daizo Group relates to a residual toner fall prevention device in the first electrostatic electrophotographic apparatus of the present invention, and FIG. 1 is a schematic perspective view of the residual toner fall prevention device; Figure 2 is a side view of the main parts.

The paper guide 7, the transfer charger case 9a, and the peel-off charger case lla are integrally formed of metal such as stainless steel, aluminum, or steel, and the partition plate a between the transfer charger case 9a and the peel-off charger case lla is This is common to charger cases 9a and Ila. Both charger cases 9a. In 11a,
Charger wires 9b and tib serving as t-poles are stretched.

A pair of peeling claws 1 that come into contact with and separate from the photosensitive drum 1
Insulator 1G in the partition via in the part corresponding to 3.
is attached. As the insulator 1G, for example, PET
An insulating sheet made of polyethylene terephthalate (polyethylene terephthalate) or the like is used, and this insulating sheet is attached to the partition plate a using double-sided adhesive tape from one side of the partition plate a, passing through the upper end and extending to the other side. Of this insulator 16, the portion of the nine transfer chargers is required, but it is pasted across both sides of the partition plate a in order to facilitate the pasting work and ensure strength of pasting.

Note that the insulator 16 is a PET sheet, and its thickness is 1
The length l of the PET sheet is approximately 8 μm to 1 mm, and the length l of the PET sheet is 2 mm</, <12 mm for ease of assembly, relative to the depth l2 (10 to 30 mm) of the transfer charger case 9a.
-Q. A range of 3 mm is preferable.

The rest of the structure is the same as that of the conventional example, so a description thereof will be omitted.

Next, the operation of the residual toner drop prevention device of this embodiment will be explained.

? The output current of the high-voltage unit 1o in the photosensitive drum 9 is It, the discharge current flowing from the transfer charger 9b to the transfer charger case 9a is Ic, and the photosensitive drum 1
The discharge current flowing into ■.

Then, It=I, +I.

The relationship is established.

However, in the region where the insulator 16 exists, the impedance (2) to the discharge current increases, so the discharge current (2) to the transfer charger case 9a increases. decreases, and the output current is 1t.
Since ! is constant, the radiation to the photoconductor drum 1! current I
0 increases.

As the discharge current I0 increases, the efficiency of transferring the toner T on the photoconductor drum 1 to the transfer paper 8 increases, and the photoconductor drum increases in the area where the insulator l6 is present, that is, in the area where the #J and l claws 13 come into sliding contact. The amount of residual toner on 1 is reduced. Therefore, the amount of toner adhering to the @M claw 13 is reduced, the degree of staining of the @release claw 13 is slowed down, and the #
The amount of toner T falling from the I# nail 13 is reduced, and the transfer paper 8
can prevent stains.

Incidentally, as shown in FIG. 3, the same effect can be expected even if a continuous insulator 17 is pasted between the two parts corresponding to the pair of peeling claws 13, and only one piece of insulator 17 is required. This improves the workability of pasting.

In the above embodiment, the transfer charger 9 and the peeling charger 1
Although the chargers 9 and 11 were integrated, the same effect can be achieved even if both chargers 9 and 11 are separated.

The second embodiment of Fude 1 Daijoban relates to a residual toner fall prevention device in a second electrostatic electrophotographic apparatus of the present invention, and FIG. 4 is a schematic perspective view of the residual toner fall prevention device; FIG. 5 is a side view of the main part.

A pair of separation claws l that come into contact with and separate from the photoreceptor drum 1
In the part corresponding to 3, #l in the remote charger 1l! II separation charger wire Ilb connects to photoreceptor drum 1
Of the portions facing each other, portions corresponding to the pair of peeling claws 13 are covered with an insulator 18. As this insulator 18, an insulating sheet such as PET (polyethylene terephthalate) is used as described above. Such an insulating sheet is stretched across the upper ends of the transfer charger case 9a.

This insulator 18 is different from the insulators 16 and 17 in the first embodiment that are attached to the side surface of the partition Fia, and does not reduce the discharge current to the peeled charger case lla. Rather, it reduces the discharge current to the stripped charger wire llb, resulting in the discharge of NTK. to the stripped charger case 11a. Even if the flow increases, this has no bearing on preventing the residual toner T from falling off.

The rest of the configuration is the same as the conventional example, so the explanation will be omitted.

Next, the operation of the residual toner drop prevention device of this embodiment will be explained.

In the area where the insulator 18 is present, the photoreceptor drum 1 and the peelable charger wire 1. 1 Since it shields between b and
The discharge current It between the peeling charger wire llb and the photoreceptor drum 1 is reduced, and a potential drop on the surface of the photoreceptor drum 1 is prevented. Therefore, in the area where the insulator 18 is present, that is, the area where the peeling claw 13 comes into sliding contact, a decrease in the adsorption force of the residual toner T by the photosensitive drum 1 is prevented, and peeling of the toner T due to the sliding contact of the peeling claw 13 is suppressed. Therefore, staining of the transfer paper 8 can be prevented.

Note that even if the peeling charger 11 is separate from the transfer charger 9, the same effect can be achieved. Alternatively, a continuous insulator may be attached between two portions corresponding to the pair of peeling claws 13.

<Effects of the Invention> ■ According to the first residual toner fall prevention device in an electrostatic electrophotographic apparatus of the present invention, the insulator attached to the transfer charger case corresponding to the peeling claw prevents residual toner from flowing into the transfer charger case. As a result, reducing the flow of
The amount of toner transferred from the photoreceptor drum to the transfer paper is increased by increasing the amount of toner flowing to the photoreceptor drum in the area corresponding to the peeling nail, thereby reducing the amount of residual toner on the photoreceptor drum. It is possible to reduce the amount of toner that is detected by the peeling claw or the amount of toner that falls from the peeling claw, without causing problems in terms of cost and space when installing a toner receiving tray on the transfer paper. can prevent stains.

According to the second residual toner fall prevention device in an electrostatic electrophotographic apparatus of the present invention, by covering the peeling charger wire in the peeling charger with an insulator, the peeling charger wire and the photoreceptor drum are connected to each other at a portion corresponding to the peeling claw. Since the discharge current between the photoreceptor drum and the photoreceptor drum is reduced and the potential of the photoreceptor drum is prevented from decreasing, the ability to attract residual toner on the photoreceptor drum is prevented from decreasing, and staining of the transfer paper can be prevented in the same way as described above.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 and FIG. 2 relate to the first embodiment of the present invention.
The figure is a schematic perspective view of a residual toner fall prevention device in an electrostatic electrophotographic apparatus, and FIG. 2 is a side view of the main parts thereof. FIG. 3 is a schematic perspective view of a residual toner fall prevention device according to an applied example of the first embodiment. Figures 4 and 5
The figures relate to the second embodiment, FIG. 4 is a schematic perspective view of a residual toner fall prevention device in an electrostatic electrophotographic apparatus, and FIG.
The figure is a side view of the main parts. 6 to 8 relate to conventional examples, where FIG. 6 is an explanatory diagram of the copying process of a general copying machine, FIG. 7 is an explanatory diagram of the transfer step, and FIG. 8 is an explanatory diagram of the peeling step. . 1... Photosensitive drum, 2... Main charger, 4
...Exposure optical system, 5...Development unit, 6...Magneft roller, 8...Transfer paper, 9...Transfer charger, 9a...Transfer charger case, 9b...Transfer charger Wire, 10...High pressure unit, 1l.
...'AM charger, lla...separation charger case, llb...separation charger wire, 12...
High pressure unit, l3... Peeling claw, 14... Cleaning blade, 15... Static elimination lamp, 16.17.1
8...Insulator, T...Toner

Claims (2)

[Claims] (1) An electrostatic latent image is formed on the surface of the charged photoreceptor drum by light irradiation, the electrostatic latent image is developed into a visible image by attaching toner to the surface of the photoreceptor drum, and the transfer charger The toner forming the visible image is transferred to the transfer paper along the surface of the photoreceptor drum by the electric discharge of In an electrostatic electrophotographic apparatus configured to mechanically peel off the transfer paper that has not been peeled off by the peeling charger from the photoreceptor drum using a peeling claw, at least one of the transfer charger cases in the transfer charger A residual toner fall prevention device for an electrostatic electrophotographic apparatus, characterized in that an insulator is attached to a portion corresponding to the peeling claw. (2) An electrostatic latent image is formed on the surface of the charged photoreceptor drum by light irradiation, the electrostatic latent image is developed into a visible image by attaching toner to the surface of the photoreceptor drum, and the transfer charger The toner forming the visible image is transferred to the transfer paper along the surface of the photoreceptor drum by the electric discharge of In an electrostatic electrophotographic apparatus configured to mechanically peel off the transfer paper that has not been peeled off by the peel charger from the photosensitive drum using a peel claw, the peel charger wire in the peel charger 1. A residual toner fall prevention device for an electrostatic electrophotographic apparatus, characterized in that at least a portion corresponding to the peeling claw among the portions facing the body drum is covered with an insulator.