JP5099844B2 - Static eliminator and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the unevenness of charge eliminating light quantity and further reduce the influence on charging performance. <P>SOLUTION: The charge elimination device 1 for eliminating charge of the surface of a photoreceptor drum 101 comprises: a plurality of light sources 2 disposed substantially in parallel to an axis 101a of the photoreceptor drum 101; and an elliptic diffusion plate 3 for diffusing and emitting light from the light source 2 to the photoreceptor drum 101, the plate being provided between the plurality of light sources 2 and the photoreceptor drum 101. The diffusion plate 3 is disposed so that one main surface 31 is opposed to the plurality of light sources 2 and the other main surface 32 is opposed to the photoreceptor drum 101, and has a structure such that the light, when passed through the diffusion plate 3, is diffused more widely in a direction substantially parallel to the axis 101a than a direction vertical to the axis. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a static eliminator and an image forming apparatus such as a printer, a copier, and a facsimile machine using the static eliminator.

  In an electrophotographic image forming apparatus, a charging device, an exposure device, a developing device, a transfer device, a cleaning device, a static eliminating device, and the like are provided around the photosensitive drum. After the surface of the photosensitive drum is uniformly charged by the charging device, exposure is performed by the exposure device to form an electrostatic latent image on the surface of the photosensitive drum and developed by the developing device. Thereafter, the developed toner image is transferred onto a recording medium by a transfer device. Then, the recording medium is conveyed to the fixing device and fixed, and then discharged outside the device. On the other hand, the toner remaining on the photosensitive drum during the transfer is removed by a cleaning device.

  In such an image forming apparatus, after cleaning of the photosensitive drum, residual charges on the photosensitive drum are removed (hereinafter referred to as static elimination) by the static eliminator, and the photosensitive drum is charged again by the charging device. By removing the residual electrification before charging, the subsequent uniform charging of the surface of the photosensitive drum can be realized. In addition, not only after cleaning but also after the transfer, there are cases where static elimination is performed before cleaning.

  For neutralization of residual charge, neutralization by light or electrical charge removal such as AC charge is used. However, light discharge is the mainstream from the viewpoint of cost and safety, and multiple inexpensive LEDs are arranged as a light source. This configuration is generally used.

  FIG. 7 is a plan view of the static elimination device 1600 and the photosensitive drum 1000 and a diagram showing the quantity of static elimination at the position of the photosensitive drum 1000 in the axis 1000a direction. As shown in FIG. 7, the static eliminator 1600 includes a point light source 1601 including a plurality of LEDs provided along the direction of the axis 1000 a of the photosensitive drum 1000. An arrow extending from the point light source 1601 indicates the spread of light.

  In the static eliminator 1600 using a plurality of such point light sources 1601, as shown in the graph 2000 of FIG. 7, the amount of light at the position J <b> 1 facing the point light source 1601 is large, and the position J <b> 2 facing between the point light sources 1601 Since the amount of light is small, unevenness is likely to occur in the bright spot of the light source. A point on the graph 2000 corresponding to the position J1 is shown as K1, and a point on the graph 2000 corresponding to the position J2 is shown as K2. FIG. 8 is a diagram showing the relationship between the amount of charge removed on the photosensitive drum and the surface potential. From FIG. 8, it can be seen that there is a correlation between the charge removal amount and the surface potential, and when unevenness occurs in the charge removal light, unevenness occurs in the surface potential of the photosensitive drum.

  In order to avoid this unevenness, the number of point light sources 1601 is increased and the distance between the light sources is shortened, the light emission spread angle of the point light source 1601 itself is increased, and the distance between the point light source 1601 and the photosensitive drum 1000 is increased. By taking a long time, unevenness of bright spots is suppressed, and unevenness of the charge removal amount on the photosensitive drum 1000 is reduced.

  However, when the number of light sources is increased in this way, the cost increases, and when the distance between the light sources 1601 and the photosensitive drum 1000 is increased, there arises a problem that the apparatus becomes larger.

Thus, it has been proposed to dispose a diffusion plate between the static eliminator and the photosensitive drum (see, for example, Patent Document 1). By arranging the diffusing plate in this way, the light from the light source is further spread, and the bright spot unevenness due to the point light source is suppressed.
JP-A-3-33888

  However, in the configuration of Patent Document 1, as shown in FIG. 9, a part of the light diffused in the circumferential direction of the photosensitive drum 1000 by the diffusion plate 1602 arranged between the light source 1601 and the photosensitive drum 1000 ( (Indicated by an arrow A) may enter the charging device 1100 side that is disposed next to the static elimination device 1600.

  As described above, when the static elimination light enters the charging device 1100 side, the surface potential further decreases, the charging performance may be lowered, or the charged surface of the photosensitive drum 1000 may be eliminated again, which affects the charging performance. May give. In FIG. 9, a charging device of a non-contact type (for example, a charging charger) is illustrated as the charging device 1100, but even when a charging device of a contact type (for example, a charging roller) is used. A similar problem occurs because the surface potential is lowered due to the penetration of the neutralizing light, and the charged surface may be neutralized again by the penetrating light.

  In view of the above-described problems of the conventional image forming apparatus, it is an object of the present invention to provide a static eliminator and an image forming apparatus capable of suppressing unevenness in the amount of static eliminator and also suppressing the influence on charging performance. Objective.

In order to achieve the above object, the first present invention provides:
A static eliminator for neutralizing the surface of an image carrier,
A plurality of light sources arranged substantially parallel to the axis of the image carrier;
A plate-like diffusion member provided between the plurality of photogenerators and the image carrier, for diffusing light from the light source and irradiating the image carrier;
The diffusion member is
One of the main surfaces is arranged to face the plurality of light sources, and the other main surface is arranged to face the image carrier,
The static eliminator has a structure in which, when the light passes through the diffusing member, the direction substantially parallel to the axis is diffused more than the direction perpendicular to the axis.

The second aspect of the present invention is
It is a static elimination apparatus of 1st this invention provided with the light guide member provided between the said several light source and the said diffusion member which guides the light from these several light sources to the said diffusion member.

The third aspect of the present invention
An image carrier on which an electrostatic latent image is formed on the surface;
An image forming apparatus comprising the first or second neutralization device of the present invention for neutralizing residual charges on the surface of the image carrier.

  ADVANTAGE OF THE INVENTION According to this invention, the static elimination apparatus and image forming apparatus which can suppress the nonuniformity of the static elimination light quantity and can also suppress the influence which it has on charging performance can be provided.

  Hereinafter, a copier as an example of an image forming apparatus according to the present invention will be described with reference to the drawings, and an example of a static eliminator according to the present invention will be described at the same time.

(Embodiment 1)
FIG. 1 is a front view of the copying machine 100 according to the first embodiment of the present invention. The copying machine 100 is a copying machine that forms a monochrome image, and includes a document reading device 120 that reads an image of a document with an exposure lamp, a lens, a mirror, and the like at the top, and stores paper at the bottom. A plurality of paper feed cassettes 130 are provided.

  Further, the copying machine 100 includes an image forming unit 110 that creates a toner image based on image data read by the document reading device 120 from the center left.

  FIG. 2 is a front view schematically showing the image forming unit 110.

  As shown in FIGS. 1 and 2, the image forming unit 110 is read by an a-Si (amorphous silicon) photosensitive drum 101, a charging device 111 that charges the photosensitive drum 101, and a document reading device 120. Based on the obtained image data, an exposure device 112 (see arrow T in FIGS. 1 and 2) for forming an electrostatic latent image on the photosensitive drum 101, and toner is attached to the electrostatic latent image on the photosensitive drum 101. A developing device 113 that forms a toner image, a transfer device 114 that transfers the toner image onto a sheet, a cleaning device 115 that polishes the surface of the photosensitive drum 101, and residual charges on the surface of the photosensitive drum 101. A neutralizing device 1 for neutralizing the electric charge is provided. An example of the image carrier of the present invention corresponds to the photosensitive drum 101 of the present embodiment.

  The transfer device 114 includes a transfer roller 114 a that presses the photosensitive drum 101 and a pressing mechanism 114 b that presses the transfer roller 114 a against the photosensitive drum 101. The developing device 113 includes a developing roller 113a that supplies toner to the photosensitive drum 101, and a conveying screw 113b that conveys the toner from the toner tank to the developing roller 113a while stirring.

  The cleaning device 115 includes a rubbing roller 116 that presses the photosensitive drum 101 and a scraper 117 that abuts against the rubbing roller 116. Further, a rubber blade 118 that contacts the surface of the photosensitive drum 101 and scrapes off residual toner, a rubbing roller 116, a scraper 117, and a recovery roller that recovers toner removed from the surface of the photosensitive drum 101 by the rubber blade 118. 119 is provided.

  Further, as shown in FIG. 1, a fixing unit 140 for fixing the transferred toner image on the sheet is provided on the downstream side of the photosensitive drum 101 with respect to the sheet conveyance direction V. On the further downstream side of the fixing unit 140, a discharge roller 150 and a discharge tray 160 on which the paper discharged by the discharge roller 150 is placed are provided.

  Next, the structure of the static elimination apparatus 1 of this Embodiment is demonstrated.

  FIG. 3 is a cross-sectional configuration diagram of the static eliminator 1 of the present embodiment. FIG. 4 is a plan view of the static elimination device 1 and the photosensitive drum 100 of the present embodiment, and a diagram showing the quantity of static elimination at the position of the photosensitive drum 101 in the axis 101a direction. In addition, the arrow from the point light source 2 in FIG.3 and FIG.4 has shown the breadth of light.

  As shown in FIG. 4, a point light source 2 composed of a plurality of LEDs is provided substantially in parallel with the direction of the axis 101 a of the photosensitive drum 101. Further, as shown in FIGS. 3 and 4, the light of the point light source 2 is diffused between the plurality of point light sources 2 and the photosensitive drum 101 to irradiate the photosensitive drum 101 of the present invention. An elliptical diffusion plate 3 that is an example of a diffusion member and a light guide plate 4 that is an example of the light guide member of the present invention for guiding light from the point light source 2 to the elliptical diffusion plate 3 are provided. One end surface of the light guide plate 4 is an incident surface 41 on which light from the light source 2 is incident, and an end surface opposed to the incident surface 41 is an output surface 42 from which light is emitted. On the other hand, the elliptical diffuser plate 3 is disposed such that one main surface is in close contact with the exit surface 42 as the entrance surface 31 and the other main surface is opposed to the photosensitive drum 101 as the exit surface 32. The incident surface 31 also faces the point light source 2. In FIG. 3, the main surface of the light guide plate 4 is arranged in the vertical direction. An example of one main surface of the present invention corresponds to the incident surface 31 of the present embodiment, and an example of the other main surface of the present invention corresponds to the output surface 32 of the present embodiment.

  FIG. 5 is a diagram showing a state where light from one light source 2 has passed through the elliptical diffusion plate 3. As shown in FIG. 5, the light emitted from the light source 2 passes through the light guide plate 4 while spreading in all directions at a constant rate, and is irradiated onto the elliptical diffusion plate 3. The light irradiated on the elliptical diffusion plate 3 is indicated by reference numeral 20.

  The elliptical diffuser 3 diffuses the incident light so that it spreads in the direction parallel to the axis 101a (arrow X direction in the figure), and spreads as much as possible in the direction perpendicular to the axis 101a (arrow Y direction in the figure). It has a surface structure that does not diffuse. Since it has such a surface structure, when circular light passes through the elliptical diffusion plate 3, it becomes elliptical light having a long axis in a direction parallel to the axis 101a. In the figure, reference numeral 21 denotes a portion of the light emitted from the point light source 2 that is not diffused and spreads in all directions from the point light source 2 at a certain rate, and the surrounding area 22 is a point. A diffused portion of the light emitted from the light source 2 is shown.

  As described above, since the light from one point light source 2 spreads in the direction of the axis 101a, the static elimination light in the direction of the axis 101a can be made more uniform as shown in the graph 200 of FIG.

  Further, as shown in FIGS. 3 and 5, since the spread of the light from the light source 2 in the direction perpendicular to the axis 101a is suppressed, it is possible to suppress the diffusion of the light toward the charging device 111. Therefore, even if a diffusing plate is arranged, it is possible to suppress the occurrence of deterioration in charging performance.

  As the elliptical diffuser plate 3, for example, a lens diffuser made by Luminit LLC that can be diffusely shaped into an elliptical shape can be used.

  In the elliptical diffuser plate 3 of the present embodiment, the diffusion in the direction perpendicular to the direction of the axis 101a is suppressed as much as possible in the light before and after passing through, but at least the direction parallel to the axis 101a is the same as the axis 101a. What is necessary is just to diffuse more than the perpendicular | vertical direction, the variation in static elimination light can be suppressed, and the influence which it has on the charging device 111 can be suppressed compared with the past.

  Here, the fact that the direction parallel to the axis 101a (arrow X direction in FIG. 5) diffuses more than the direction perpendicular to the axis 101a (arrow Y direction in FIG. 5) is shown in FIGS. This will be described with reference to b). 6A is a view seen from the direction of the axis 101a, and FIG. 6B is a view seen from the direction perpendicular to the axis 101a.

  In FIG. 6A, the angle that spreads in the direction perpendicular to the axis 101a between the light Nb before passing through the elliptical diffuser plate 3 and the light Na after passing through is large from α to β with reference to the optical axis 2s. It has become. On the other hand, in FIG. 6B, the angle of the light Nb before passing through the elliptical diffuser plate 3 and the light Na after passing through in the direction parallel to the axis 101a is changed from γ to δ with respect to the optical axis 2s. Is getting bigger. That the direction parallel to the axis 101a diffuses more than the direction perpendicular to the axis 101a means that before and after passing through the elliptical diffusion plate 3, the direction parallel to the axis 101a is greater than the direction perpendicular to the axis 101a. The rate at which the light spread angle increases is large, which corresponds to (β / α) <(δ / γ). In the present embodiment, since the light emitted from the point light source 2 is circular, the light before passing through the elliptical diffuser 3 spreads evenly in all directions, so α and γ are substantially equal values. It has become.

  In addition, an elliptical light source may be used instead of a circular irradiation light, but in order to reduce diffusion in the circumferential direction of the photosensitive drum 101, the major axis direction of the ellipse coincides with the axial direction of the photosensitive drum 101a. It is preferable to arrange the light sources so as to have such a light distribution.

  In FIG. 2, a charging device of a non-contact type (for example, charging charger) is shown as the charging device 111, but a charging device of a contact type (for example, charging roller) may be used.

  In the present embodiment, the light guide plate 4 is provided between the light source 2 and the elliptical diffusion plate 3, but the light guide plate 4 may not be provided. However, the arrangement of the light guide plate 4 can reduce the diffusion in the direction perpendicular to the axis 101a (the circumferential direction of the photosensitive drum 101) until the static elimination light from the light source 2 reaches the elliptical diffusion plate 4. This makes it possible to increase the irradiation efficiency of the static elimination light and to prevent the influence on the charging device.

  Further, in order to reduce the diffusion in the circumferential direction of the photosensitive drum 101 and suppress the influence on the charging device, a thin film sheet such as a black mirror may be arranged instead of the light guide plate 4, but an elliptical diffusion plate Since there is light that is absorbed by the thin film sheet until the light reaches 3, the irradiation efficiency is lowered. On the other hand, when the light guide plate 4 is used, since it is totally reflected on the main surface (indicated by reference numeral 43 in FIG. 4), it is possible to suppress a decrease in irradiation efficiency, which is more preferable.

  In this embodiment, the light source 2, the light guide plate 4, and the elliptical diffuser plate 3 are arranged in this order. However, the light source 2, the elliptical diffuser plate 3, and the light guide plate 4 may be arranged in this order. However, it is more preferable to shorten the distance between the light source 2 and the elliptical diffusion plate 3 as much as possible because it is possible to reduce the diffusion of the static elimination light in the circumferential direction of the photosensitive drum 101.

  The image forming apparatus of the present invention has been described by taking a monochrome copying machine as an example, but it may be a color copying machine, a printer, or a facsimile.

  According to the neutralization device and the image forming apparatus of the present invention, it has the effect of reducing unevenness of the neutralization light amount and suppressing the influence on the charging performance, and is useful as a printer, a facsimile machine, a copying machine, and the like. .

1 is a front configuration diagram of a copying machine according to a first embodiment of the present invention. 1 is a configuration diagram of an image forming unit 110 according to a first embodiment of the present invention. Cross-sectional block diagram of the static elimination apparatus 1 in Embodiment 1 concerning this invention The top view of the static elimination apparatus 1 and the photosensitive drum 101 in Embodiment 1 concerning this invention, and the figure which shows the relationship between the static elimination light quantity in the position of the axial direction of a photosensitive drum. The figure which shows the state which the light from the one light source 2 in Embodiment 1 concerning this invention passed the elliptical diffuser plate 3 The top view seen from the axial direction of the photoconductive drum for demonstrating the spreading | diffusion of the light by the elliptical diffusing plate in Embodiment 1 concerning this invention FIG. 3 is a plan view seen from a direction perpendicular to the axis of the photosensitive drum for explaining light diffusion by the elliptical diffusion plate according to the first embodiment of the present invention; The top view of the conventional static elimination apparatus and a photosensitive drum, and the figure which shows the relationship of the static elimination light quantity in the position of the axial direction of a photosensitive drum The figure which shows the relationship between the amount of static elimination on the photosensitive drum and the surface potential Configuration diagram of the vicinity of a static elimination unit in a conventional image forming apparatus

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Static elimination apparatus 2 Light source 3 Elliptical diffuser plate 4 Light guide plate 100 Copy machine 101 Image forming unit 111 Charging apparatus 112 Exposure apparatus 113 Developing apparatus 114 Transfer apparatus 115 Cleaning apparatus 116 Photosensitive drum 120 Document reading apparatus 130 Paper feed cassette 140 Fixing unit 150 Discharge roller 160 Discharge tray

Claims (3)

A static eliminator for neutralizing the surface of an image carrier,
A plurality of light sources arranged substantially parallel to the axis of the image carrier;
A plate-like diffusion member provided between the plurality of photogenerators and the image carrier, for diffusing light from the light source and irradiating the image carrier;
The diffusion member is
One of the main surfaces is arranged to face the plurality of light sources, and the other main surface is arranged to face the image carrier,
The static eliminator having a structure in which when the light passes through the diffusing member, the direction substantially parallel to the axis is diffused more than the direction perpendicular to the axis.   The static eliminator according to claim 1, further comprising a light guide member that is provided between the plurality of light sources and the diffusion member and guides light from the plurality of light sources to the diffusion member. An image carrier on which an electrostatic latent image is formed on the surface;
An image forming apparatus comprising: the static eliminator according to claim 1 or 2 for neutralizing residual charges on the surface of the image carrier.