JPH09134100A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively attain destaticization by reverse electrification of a photoreceptor and to make the contact of a destaticization member with the photoreceptor uniform by providing a loop-like destaticization member whose loop part between end parts is in contact with the surface of the photoreceptor cleaned by a cleaning means and going to a photodischarger. SOLUTION: A detaticization brush 7 is installed between a cleaning device and a photodischarge lamp and constituted in such a manner that both ends of a large number of wire-like bodies 73 arrayed actually in parallel with each other with a high density are fixed on metal plates 71 and 72 made of aluminum, etc., the wire-like bodies 73 are turned up to curve in the intermediate parts of the wire-like bodies 73 and the metal plates 71 and 72 are laid one on top of the other. In other words, the wire-like bodies 73 are formed like a loop. This loop-shaped part is pressed on the photoreceptor 1 and the wire-like bodies 73 are in contact with the surface of the photoreceptor over a long distance in the rotational direction of the photoreceptor 1, by the pressing. Thus, contact pressure is actually made constant and uniform by the elasticity of the loop.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus. The device is, for example, a copying machine, a facsimile or a printer.

[0002]

2. Description of the Related Art For example, in an image forming apparatus of this type which charges a photoconductor using a charging roller as a contact charging means, for example, referring to FIG. 3, a developing device 4, a bias application type transfer belt 5, a cleaning device 6, and a light discharging lamp 8 are arranged. As the developing method, reversal development (negative-positive development) is used in which toner is attached by the developing device 4 where the exposure (optical writing) is performed by the exposure device 3. The description of the flow of the image forming process from the charging roller 2 to the cleaning device 6 is based on the ordinary electrophotographic copying process, and will be omitted.

[0003]

When the photoconductor 1 is an organic photoconductor, it is sensitive to a negative potential. The bias characteristics of the respective members in this case are negative bias for the charging roller 2, negative for the developing device 4, negative for toner, and positive bias for the transfer belt 5. Therefore, the surface potential of the photoconductor shifts to the positive side, depending on the transfer conditions.

In the negative-positive developing system, the toner image on the photoconductor 1 is transferred onto a transfer paper by the transfer belt 5 having a bias (or charge) of the same polarity as the charging potential of the photoconductor 1. Due to the transfer bias (charge), a potential having the opposite polarity to the potential applied by the charging roller 2 is generated on the photoconductor 1. This changes depending on the transfer bias condition, but since the writing potential is particularly low in the part where the toner image is present, the charging potential may be low, and therefore, the reverse charging is likely to occur.

Normally, the photosensitive member 1 has the effect of removing the light by the light of the light removing lamp 8 only in either positive or negative polarity. Therefore, the reverse charging due to transfer is
The charge cannot be removed by the photo-electrification lamp 8 and the photosensitive member 1 proceeds to the charging roller 2 of the next step with the potential unevenness.

The charging roller 2 is used for the purpose of suppressing the generation of ozone, and when such a contact charging member is used, in order to uniformly charge the photoconductor 1 having uneven potential, an AC bias is applied. Two methods are conceivable: applying a superposed DC bias to the contact charging member, and providing a reverse charge eliminating means other than light eliminating (light eliminating lamp 8). In this method, since AC is applied, the cost of the high-voltage power source increases and there is a risk of leakage. The contact method (roller, brush, mylar,
There is a blade) and a non-contact type (corotron charger, scorotron charger, pin corotron charger), but the non-contact type produces a large amount of ozone and is not preferable in terms of configuration. In addition, the cost of the roller and the blade of the contact-type static eliminator increases.

Regarding the stabilization of the charging potential, it is proposed to arrange a charging roller in parallel (Japanese Patent Laid-Open No. 56-91253) and a contact type pre-charging unit in front of the light discharging unit (Japanese Laid-Open Patent Publication No. 6-83249). However, in general, in order to bring the charge removal brush into contact with the member to be charged, in order to prevent abrasion of the member to be charged, the brush is brought into contact with the rotating direction of the member to be charged in a training manner. That is, the tip of the brush is brought into contact with the photoconductor so as to face the downstream side in the rotation direction of the photoconductor.

A first object of the present invention is to effectively carry out reverse charge removal of the photoconductor, and a second object thereof is to make uniform contact of the charge removal member used for that purpose with the photoconductor. A third object is to provide a stable contact charge removing member at low cost.

[0009]

SUMMARY OF THE INVENTION The present invention is directed to a photosensitive member, a charging member for charging the photosensitive member, an exposure device for irradiating the photosensitive member with light to form a latent image, and a developing process using the latent image as a toner image. An image forming apparatus including a container, a transfer unit for transferring the toner image onto a transfer sheet, a cleaning unit for cleaning the photoconductor after the transfer, and a photo-electrification member for removing the electric charge of the photoconductor after the cleaning. It is characterized in that a loop-shaped charge eliminating member in which a loop portion between the end portions is in contact is provided on the surface of the photoconductor which is cleaned by the cleaning means and is directed to the light eliminating member.

According to this, for example, in the case of image formation by the mechanism shown in FIG. 1 described above, by applying a negative potential to the charge eliminating member, the above-mentioned reverse charging is eliminated. Since the static eliminating member is in a loop shape and contacts the photoconductor at the loop portion and the contact pressure becomes uniform due to the elasticity of the loop, the contact becomes uniform. Further, the loop shape can be easily formed by folding a linear or plane static eliminating member back to a U shape and fixing both ends thereof, as in Examples described later, and can be manufactured at low cost.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A static eliminator according to a first embodiment of the present invention is a static eliminator brush having a large number of loop-shaped conductive linear bodies, and the large number of linear bodies are substantially mutually. The loop surfaces of the linear members are parallel to each other and are slightly inclined with respect to the moving direction of the photosensitive member, and a resistance of 10 ³ to 10 ⁸ Ω is provided between the end portion and the position where the photosensitive member is in contact with the photosensitive member. To have.

The charge eliminating member of the second embodiment of the present invention is a loop-shaped conductive charge eliminating sheet, and 10 ³ to 10 ⁸ Ω is provided between the end of the charge eliminating member and the position where it contacts the photosensitive member. Have resistance.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[0014]

【Example】

-First Embodiment- The image forming mechanism is shown in FIG. 1, and a charge eliminating brush 7 is installed between the cleaning device 6 and the optical charge eliminating lamp 8. As shown in FIG. 2 (a), the static elimination brush 7 has a plurality of linear bodies 73, which are arranged substantially in parallel with each other and are densely arranged, having both ends thereof fixed to sheet metals 71, 72 made of aluminum or the like. Form 73
The linear body 73 is folded back so as to be bent at the middle portion of the sheet metal, and the sheet metals 71 and 72 are overlapped as shown in FIG. As a result, the linear body 73 has a loop shape. In FIG. 1, the looped portion is pressed against the photoconductor 1. By this pressing, the linear body 73 comes into contact with the surface of the photoconductor 1 over a long distance in the rotation direction of the photoconductor 1. This state is shown in FIG. 3B is a plan view of the charge removal brush 7 seen from the inside of the photoconductor 1 through the photoconductor 1 in the direction of arrow B, as shown in FIG. 3A. Due to the elasticity of the loop,
The contact pressure is substantially constant and uniform. In this embodiment, as described above, the image forming mechanism of FIG. 1 has the charging roller 2 with a negative bias, the developing device 4 with a minus, the toner with a minus, the transfer belt 5 with a plus bias, and the transfer bias of the transfer belt 5 ( (Charge) causes a positive potential having a polarity opposite to that of the negative potential applied by the charging roller 2 to be generated on the photoconductor 1, so that a negative potential is applied to the charge removal brush 7 to cause the photoconductor 1 to move. Remove the positive potential.

-First Modification of First Embodiment- As shown in FIG. 4 (a), the sheet metal 71 at one end is displaced from the sheet metal 72 at the other end in the longitudinal direction of the sheet metal 71 at the other end, as shown in FIG. As shown in (b) of FIG.
Be inclined to the moving direction of. In addition, (b) of FIG.
3 is a drawing corresponding to FIG. By thus orienting the posture of the linear body 73 of the static eliminator brush 7 so as to be slanted, it is possible to form an angle with respect to the photoconductor advancing direction. By thus providing an angle with respect to the traveling direction, one point on the photoconductor crosses the plurality of linear bodies 73. As a result, uneven charge removal in the longitudinal direction of the photoconductor 1 (direction in which the rotation axis extends) can be suppressed. In addition, it is possible to reduce the flocking density of the brush 7 (the distribution density of the linear bodies: the longitudinal direction of the photoconductor 1), and it is possible to further reduce the cost. -Second Modification of First Embodiment-As shown in FIG. 5, if the sheet metals 71 and 72 are bent in a V-shape, the contact pressure is the same as that without bending, even if the contact pressure is the same. , The linear member 73 with respect to the traveling direction of the photoconductor
The contact length can be increased. As a result, it is possible to suppress abrasion of the photoconductor.

In any of the above examples, if the linear body 73 of the brush 7 has high conductivity, the load of the high voltage power source for applying a negative bias thereto can be reduced. However, if the photoconductor 1 is defective, there is a possibility that a leak to the photoconductor will occur there. Therefore, the linear body 73 is the linear body 73.
Is preferably one having a certain degree of electrical resistance. This resistance value is determined by the conductive member such as aluminum (on which the linear member 7
(3 is in contact) and a bias voltage is applied to the linear body 73, and between the metal plates 71, 72 and the conductive member,
It may be about 10 ³ to 10 ⁸ Ω. As a result, the capacity of the high-voltage power supply that applies the bias voltage to the linear member 73 can be low, and the cost of the power supply unit can be reduced. In addition, leakage due to defects in the photoconductor is substantially prevented.

The metal plates 71 and 72 are made of synthetic resin, and when the metal plates 71 and 72 are welded to the ends of the linear members 73, conductor wires extending in the longitudinal direction of the metal plates are brought into contact with the ends of the linear members 73. You may make it embed in a sheet metal with an edge part.

-Second Embodiment- Instead of the reverse charging and discharging brush 7 (FIGS. 1 and 2) of the first embodiment, the sheet-type reverse charging and discharging brush 7 shown in FIG. 6B is used.
Is used. As shown in FIG. 6 (a), this static elimination brush 7 has a sheet of metal 71, 72 made of aluminum or the like with both ends of a polyester sheet (trade name Mylar of Du Pont) whose conductivity is adjusted.
The sheet 74 is folded back so that the sheet 74 is bent so that the sheet 74 is bent at an intermediate portion, as shown in FIG.
1 and 72 are superposed. As a result, the filim 74 has a loop shape. The looped portion is pressed against the photoconductor 1. By this pressing, the sheet 74 contacts the surface of the photoconductor 1 over a long distance in the rotation direction of the photoconductor 1. Also in the embodiment using the sheet 74, as shown in FIG. 6 (c), if the sheet metals 71 and 72 are bent in a dogleg shape, the same contact pressure does not bend. In comparison, the contact length of the sheet 74 can be increased with respect to the traveling direction of the photoconductor. Also in this second embodiment, the resistance value of the sheet 74 is set by setting a conductive member such as aluminum (the sheet 74 is in contact with it) on the photosensitive member portion and applying a bias voltage to the sheet 74. 10 ³ to 10 ⁸ between the metal plates 71 and 72 and the conductive member in the state
Ω. As a result, the capacity of the high-voltage power supply that applies the bias voltage to the sheet 74 can be low, and the cost of the power supply unit can be reduced. In addition, leakage due to defects in the photoconductor is substantially prevented. Also in this embodiment, the sheet metal 7
1, 72 are synthetic resin, and sheet metal 7 is attached to the end of the sheet 74.
When welding 1, 72, the conductor wire extending in the longitudinal direction of the sheet metal may be brought into contact with the end portion of the sheet 74 and embedded in the sheet metal together with the end portion.

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional view of an image forming mechanism according to a first embodiment of the present invention.

2 is a perspective view showing the static elimination brush 7 shown in FIG. 1, and FIG. 2A is a perspective view showing a developed state before the linear body 73 is made into a loop shape;
It is a perspective view which shows the assembled state which made (b) the loop shape.

3A is a cross-sectional view showing the static elimination brush 7 shown in FIG. 1 in a slightly enlarged manner, and FIG. 3B is a plan view of the static elimination brush 7 seen through the photoconductor 1 in the direction of arrow B shown in FIG. 3A. is there.

4A is a perspective view showing a modified example of the static elimination brush 7 shown in FIG. 1, and FIG. 4B is a plan view of the static elimination brush 7 of the modified example seen through a photoconductor.

5 is a perspective view showing another modification of the static elimination brush 7 shown in FIG. 1. FIG.

FIG. 6 shows a static elimination brush used in the second embodiment of the present invention, (a) is a perspective view showing a developed state before forming the sheet 74 into a loop shape, and (b) is a loop. The perspective view which shows the assembled state which was made into the shape, and (c) is a perspective view which shows a modification.

[Explanation of symbols]

1: Photosensitive member 2: Charging roller 3: Exposure device 4: Developing device 5: Transfer belt 6: Cleaning device 7: Reverse charging / erasing brush 71, 72: Sheet metal 73: Linear member 74: Sheet 9: Registration roller

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masumi Sato 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Inventor Hiroshi Saito 1-3-3 Nakamagome, Ota-ku, Tokyo No. 6 In Ricoh Co., Ltd. (72) Inventor Toshiyuki Uchida 1-3-3 Nakamagome, Ota-ku, Tokyo In Ricoh Co., Ltd.

Claims (6)

[Claims] 1. A photoconductor, a charging member for charging the photoconductor,
An exposure device that irradiates the photoreceptor with light to form a latent image, a developing device that uses the latent image as a toner image, a transfer unit that transfers the toner image onto a transfer paper, and a cleaning unit that cleans the photoreceptor after the transfer. And an image forming apparatus including an optical charge eliminating member for removing charges of the photoconductor after cleaning, wherein a loop portion between end portions is formed on a surface of the photoconductor which is cleaned by the cleaning means and is directed to the optical charge eliminating member. An image forming apparatus comprising: a loop-shaped charge removing member that is in contact with. 2. The image forming apparatus according to claim 1, wherein the charge removing member is a charge removing brush having a large number of loop-shaped linear members. 3. The image forming according to claim 2, wherein the plurality of linear bodies are substantially parallel to each other, and the loop surface of the linear bodies is slightly inclined with respect to the moving direction of the photoconductor. apparatus. 4. The image forming apparatus according to claim 1, wherein the charge removing member is a loop-shaped charge removing sheet. 5. The image forming apparatus according to claim 1, wherein the charge removing member is conductive. 6. The static eliminating member has a resistance of 10 ³ to 10 ⁸ Ω between its end and a position in contact with the photoconductor.
The image forming apparatus as described in the above.