JP2011002785A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a charging failure of a photoreceptor under a low-temperature environment and an image deletion failure under a high humidity environment by heating a charging roller without adding a new member (without increasing the cost).SOLUTION: This image forming apparatus having the charging roller for charging the photoreceptor includes a charging unit case for holding the charging roller, and a discharge lamp for generating antistatic light for removing charge charged on the photoreceptor. The discharge lamp is attached to the charging unit case.

Description

 The present invention relates to an image forming apparatus such as a copying machine, a printer, or a multifunction peripheral.

  For example, in an electrophotographic image forming apparatus such as a copying machine, a printer, a multifunction machine, etc., a rubber charging roller for charging a photosensitive member is provided. If the temperature of the charging roller is low, the electric resistance of rubber As a result, the photosensitive member is poorly charged. When the charging roller is placed in a high humidity environment, the surface of the charging roller absorbs moisture, so that the discharge product adhering to the surface of the photoreceptor absorbs moisture and causes image quality such as image flow.

  In order to solve such a problem, it is effective to heat the charging roller. For example, in Patent Document 1 below, as a technique for heating a charging roller, a charging roller is embedded by embedding a heating element in a mandrel of the charging roller in order to prevent the additive from seeping out from the charging roller in a high humidity environment. Has been disclosed to reduce the humidity near the charging roller.

JP-A-8-314234

  In the technique disclosed in Patent Document 1, although the charging roller can be heated, it is necessary to attach a heating element to the core of the charging roller or to newly install a heating element member outside the charging roller. It leads to the increase in the cost for a member and a power supply member.

  The present invention has been made in view of the above-described circumstances. The charging roller is heated without adding a new member (without increasing the cost), and the charging failure of the photosensitive member in a low-temperature environment is achieved. Another object of the present invention is to provide an image forming apparatus capable of preventing poor image flow under a high humidity environment.

In order to achieve the above object, an image forming apparatus according to the present invention is an image forming apparatus including a charging roller for charging a photoconductor, and includes a charging unit case for holding the charging roller, and the photoconductor. And a static elimination lamp that generates static elimination light for removing the charged electric charge, and the static elimination lamp is attached to the charging unit case.
With such a configuration, heat generated when the static elimination lamp shines can be transmitted to the charging unit case, and the charging roller can be heated.
The neutralization lamp is generally provided in the image forming apparatus in order to remove the electric charge charged on the photoconductor, and is controlled so as to be lit for a certain period of time immediately after the power is turned on. By attaching such a static elimination lamp to the charging unit case, even when the charging roller is in a low temperature environment, the charging roller is heated by the heat from the static elimination unit case, and the resistance value of the rubber decreases. Good charging performance can be obtained without applying a particularly high voltage to the charging roller.
Even when the charging roller is placed in a high humidity environment, the saturated vapor amount increases as the temperature near the charging roller rises. Can be prevented.
Furthermore, since the static elimination lamp is originally provided in the image forming apparatus, it does not add a new member and does not increase the cost.

In the image forming apparatus according to the present invention, the charge eliminating lamp is attached to the inside of the charging unit case.
Thus, when the static elimination lamp is mounted inside the charging unit case, the charging roller can be more effectively heated by the synergistic effect of the heat radiation from the static elimination lamp itself and the heat radiation from the charging unit case.
Further, as described above, when the static elimination lamp is attached to the inside of the charging unit case, a light shielding plate is arranged so that the static elimination light does not strike the contact portion between the charging roller and the photosensitive member. It is preferable.

Furthermore, in the image forming apparatus according to the present invention, the charge eliminating lamp is attached to the outside of the charging unit case.
In this way, when the static elimination lamp is attached to the outside of the charging unit case, the charging roller is heated only by heat radiation from the charging unit case. Since there is no need to provide it, there is a merit in terms of cost.

 According to the present invention, the charging roller can be heated without adding a new member (without increasing the cost), charging failure due to the low temperature of the charging roller, and the charging roller rubber It is possible to prevent an image flow defect due to moisture absorption and to obtain an image forming apparatus that does not depend on the environment.

1 is a schematic configuration diagram of a printer (image forming apparatus) P according to an embodiment of the present invention. FIG. 4 is a detailed view of a main part of an image forming unit 10K in the printer P and a detailed configuration diagram of a charge removal lamp. It is explanatory drawing regarding the modification of this embodiment.

   Hereinafter, an embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings. In the following drawings, the scale of each member is appropriately changed in order to make each member a recognizable size. In the following description, a tandem printer will be described as the image forming apparatus of the present invention.

   FIG. 1 is a schematic configuration diagram of a printer P according to the present embodiment. As shown in FIG. 1, the printer P includes image forming units 10K, 10Y that form images (toner images) corresponding to the respective colors K (black), Y (yellow), C (cyan), and M (magenta). 10C, 10M, a laser scanning unit 20, a transfer unit 30, a fixing unit 40, toner cartridges 50K, 50Y, 50C, 50M, a paper cassette 60, and a manual feed tray 70.

  The image forming units 10K, 10Y, 10C, and 10M are arranged at predetermined intervals in the horizontal direction in order from the left side when viewed from the front of the printer P. A unit (12K, 12Y, 12C, 12M), a developing unit (13K, 13Y, 13C, 13M), and a cleaner (14K, 14Y, 14C, 14M) are provided. As described above, since the configurations of the image forming units 10K, 10Y, 10C, and 10M are common, the following description will be given focusing on the image forming unit 10K.

 The photosensitive drum 11K is a cylindrical member on which an electrostatic latent image and a toner image based on the electrostatic latent image are formed. The photosensitive drum 11K extends in the depth direction when viewed from the front of the printer P. Yes. The charging unit 12K is disposed to face the photosensitive drum 11K and charges the peripheral surface of the photosensitive drum 11K. The developing unit 13K supplies toner (here, black toner) to the peripheral surface of the photoconductive drum 11K, whereby a toner image based on the electrostatic latent image (here, black) is supplied onto the peripheral surface of the photoconductive drum 11K. Toner image) is formed (developed). The cleaner 14K removes toner remaining on the surface of the photosensitive drum 11K after the toner image is transferred from the photosensitive drum 11K to an intermediate transfer belt 31 described later.

 The laser scanning unit 20 is disposed below each of the image forming units 10K, 10Y, 10C, and 10M, and the photosensitive drums 11K, 11Y, 11K, 11Y, and 11B are charged with laser light in accordance with image data indicating an image to be printed. An electrostatic latent image corresponding to each color is formed by scanning on the peripheral surfaces of 11C and 11M.

   The transfer unit 30 is disposed above the image forming units 10K, 10Y, 10C, and 10M, and includes an intermediate transfer belt 31 for primary transfer, a driving roller 32 for rotating the intermediate transfer belt 31, and an intermediate A tension roller 33 for applying tension to the transfer belt 31, a driven roller 34 that rotates as the intermediate transfer belt 31 rotates, and toner images formed on the surfaces of the photosensitive drums 11K, 11Y, 11C, and 11M. The primary transfer rollers 35K, 35Y, 35C, and 35M for transferring to the intermediate transfer belt 31 and the toner image transferred on the intermediate transfer belt 31 are secondarily transferred to the recording paper conveyed from the paper cassette 60 or the manual feed tray 70. And a secondary transfer roller 36 for transferring.

 The toner images of the respective colors developed on the respective photoconductive drums 11K, 11Y, 11C, and 11M by the transfer unit 30 as described above are once superimposed on the intermediate transfer belt 31, and then the secondary transfer with the driving roller 32. The recording paper is transferred to the recording paper conveyed from the paper cassette 60 or the manual feed tray 70 between the rollers 36.

   The fixing unit 40 fixes the toner image transferred onto the recording paper by the transfer unit 30 by applying heat and pressure to the recording paper, and before the paper discharge port on the recording paper conveyance path. Has been placed. The toner cartridges 50 </ b> K, 50 </ b> Y, 50 </ b> C, and 50 </ b> M store toner of each color to be supplied to the developing units 13 </ b> K, 13 </ b> Y, 13 </ b> C, and 13 </ b> M, and are disposed above the transfer unit 30.

 The paper cassette 60 is a recording paper storage cassette provided at the bottom of the apparatus so as to be opened and closed in the depth direction. The recording sheets stored in the sheet cassette 60 are picked up one by one by the sheet feeding roller 61 and conveyed between the driving roller 32 and the secondary transfer roller 36. Further, the printer P picks up the recording paper set on the manual feed tray 70 installed on the side of the apparatus one by one by the paper feeding roller 71 and conveys it between the driving roller 32 and the secondary transfer roller 36. It also has a mechanism.

 The above is a description of the overall configuration of the printer P. Hereinafter, the configuration of the charging unit 12K in the present embodiment will be described in detail with reference to FIG. FIG. 2A is a detailed view of a main part of the image forming unit 10K. For convenience of explanation, in FIG. 2A, the image forming unit 10K shown in FIG. 1 is shown upside down.

 As shown in FIG. 2A, the charging unit 12K includes a charging roller 100 made of rubber (for example, epichlorohydrin rubber) disposed in contact with the photosensitive drum 11K to charge the photosensitive drum 11K, and a charging roller. A cleaning brush 101 disposed in contact with the charging roller 100 in order to clean the surface of the charging unit 100; a charging unit case 102 which is a housing for storing (holding) the charging roller 100 and the cleaning brush 101; The discharge lamp 103 is attached to a wall surface on the inner side of the case 102 and upstream of the drum rotation, and generates discharge light for removing charges charged on the photosensitive drum 11K.

 Thus, the charging roller 100 and the cleaning brush 101 are configured to be mounted inside the charging unit case 102 for reasons such as light shielding, protection from scratches, prevention of surface contamination, and ease of replacement. Further, as shown in FIG. 2B, the static elimination lamp 103 has a configuration in which a plurality of light emitting elements (for example, red LEDs) 103b and resistance elements 103c are arranged on an array on a printed board 103a. Such a charge eliminating lamp 103 is attached to the inside of the charging unit case 102 so that the light emitting surface of each light emitting element 103b faces the photosensitive drum 11K.

 In addition, a light shielding plate 104 is disposed so that the neutralizing light emitted from the neutralizing lamp 103 does not strike the nip portion (contact portion) between the charging roller 100 and the photosensitive drum 11K. The light shielding plate 104 may be provided inside the charging unit case 102 or may be provided separately from the charging unit 12K. In FIG. 2A, reference numeral 200 is a developing roller provided in the developing unit 13K, reference numeral 300 is a cleaning roller provided in the cleaner 14K, reference numeral 301 is a residual toner collecting screw provided in the cleaner 14K, Reference numeral 302 denotes a cleaning blade.

  In the charging unit 12K configured as described above, a constant voltage is applied to the static elimination lamp 103 from a control device (not shown) at a predetermined timing, for example, when the power is turned on or during a printing operation. Heat is generated from the element 103c. This heat is transmitted to the charging unit case 102 and the air inside the charging unit case 102 and the charging roller 100 are heated. The higher the linear speed machine, the higher the rotational speed of the photosensitive drum 11K and the shorter the time during which the static elimination lamp 103 can emit light. Therefore, it is necessary to increase the amount of light necessary for static elimination. Increasing the amount of electricity removed increases the amount of heat generated by the electricity removal lamp 103, so that it becomes easier to heat the charging roller 100.

The charging roller 100 is made of conductive rubber, and the resistance value varies depending on the temperature. In general, since the resistance value of rubber becomes high at low temperatures, it is necessary to increase the voltage to a level necessary for sufficiently charging the photosensitive drum 11K. In addition, since the high linear machine cannot sufficiently secure the contact time between the photosensitive drum 11K and the charging roller 100, the photosensitive drum 11K cannot be sufficiently charged unless the voltage is increased. In this way, if it is intended to be used in a low temperature environment with a high linear speed machine, a high-performance circuit capable of outputting a high voltage is required, leading to an increase in cost.
However, since the charging roller 100 is quickly heated by attaching the static elimination lamp 103 to the inner wall of the charging unit case 102, the photosensitive drum 11K can be sufficiently charged even with a low applied voltage. Lowering the applied voltage means that a low-performance circuit may be prepared, which leads to cost reduction.

In the conventional image forming apparatus, depending on the position of the charge removal lamp 103, the toner passage is close to the toner, and the heat from the charge removal lamp 103 causes the toner to melt, causing internal contamination, damage to the member due to toner fusion, etc. Also occurred. However, since the inside of the charging unit 12K is farthest from the toner, such a problem does not occur. It is possible to effectively use the heat generated by the static elimination lamp 103 that has been unnecessary until now.
Further, under a high humidity atmosphere, the charging roller 100 and adhering matter on the surface absorb moisture, so that a moisture absorption phenomenon also occurs on the surface of the photosensitive drum 11K, and the electrical resistance on the surface of the photosensitive drum 11K decreases. As a result, an image flow phenomenon in which charges flow occurs. According to the present embodiment, the charging roller 100 can be heated by energizing the static elimination lamp 103 immediately after the power is turned on, the amount of saturated vapor can be increased, and the adsorbed moisture can be evaporated. Can do.

  As described above, according to the present embodiment, since the static elimination lamp 103 is originally provided in the image forming apparatus, no new member is added and the cost is not increased. The charging roller 100 can be heated, and it is possible to prevent a charging failure due to a low temperature of the charging roller 100 and an image flow failure due to moisture absorption by the rubber of the charging roller 100.

In addition, this invention is not limited to the said embodiment, The following modifications are mentioned.
(1) In the above embodiment, the case where the static elimination lamp 103 is attached to the inside of the charging unit case 102 is illustrated, but the configuration in which the static elimination lamp 103 is attached to the outside of the charging unit case 102 as shown in FIG. It is also good. As described above, when the static elimination lamp 103 is attached to the outside of the charging unit case 102, the charging roller 100 is heated only by heat radiation from the charging unit case 102, so that the heating effect is reduced as compared with the case where it is attached to the inside. Since there is no need to provide the light shielding plate 104, there is a cost advantage.

(2) In the above embodiment, the case where the static elimination lamp 103 is attached to the inner wall of the charging unit case 102 and the wall surface in the vicinity of the cleaning brush 101 has been exemplified. For example, as shown in FIG. A configuration may be adopted in which the shape of 102 is enlarged in the vicinity of the charging roller 100 and the static elimination lamp 103 is attached to the inner wall surface of the enlarged portion. With such a configuration, since the static elimination lamp 103 is disposed near the charging roller 100, the charging roller 100 can be heated more effectively. In addition, since the distance from the charge removal lamp 103 to the contact portion between the charging roller 100 and the photosensitive drum 11K becomes longer, it is not necessary to provide the light shielding plate 104.

(3) Further, as shown in FIG. 3C, the end of the charging unit case 102 may be bent, and the charge eliminating lamp 103 may be attached to the inner wall surface of the bent end. Even in such a configuration, the distance from the static elimination lamp 103 to the contact portion between the charging roller 100 and the photosensitive drum 11K becomes long, so that it is not necessary to provide the light shielding plate 104.

(4) In the above embodiment, the printer is described as an example of the image forming apparatus of the present invention. However, the present invention is not limited to the printer, and other apparatuses such as a copying machine, a multifunction machine, and a facsimile machine are used. It can also be applied to an image forming apparatus. Further, the image forming apparatus is not necessarily a tandem image forming apparatus.

  P ... Printer (image forming apparatus), 10K, 10Y, 10C, 10M ... Image forming unit, 20 ... Laser scanning unit, 30 ... Transfer unit, 40 ... Fixing unit, 50K, 50Y, 50C, 50M ... Toner cartridge, 60 ... Paper cassette, 70 ... manual feed tray, 12K, 12Y, 12C, 12M ... charging unit, 100 ... charging roller, 101 ... cleaning brush, 102 ... charging unit case, 103 ... static elimination lamp, 104 ... light shielding plate

Claims (4)

An image forming apparatus including a charging roller for charging a photoreceptor,
A charging unit case for holding the charging roller;
A static elimination lamp for generating static elimination light for removing the electric charge charged on the photosensitive member,
The image forming apparatus, wherein the charge eliminating lamp is attached to the charging unit case.   The image forming apparatus according to claim 1, wherein the static elimination lamp is attached to the inside of the charging unit case.   The image forming apparatus according to claim 2, further comprising: a light shielding plate disposed so that the charge removal light does not strike a contact portion between the charging roller and the photosensitive member.   The image forming apparatus according to claim 1, wherein the static elimination lamp is attached to the outside of the charging unit case.

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