JPH0561280A - Image forming device - Google Patents

Abstract

PURPOSE:To provide an image forming device where the lowering of electrostatic charging potential caused by the light irradiation of a destaticizing lamp set near an electrostatic charging devil good-quality image is secured. CONSTITUTION:In the electrophotographic image forming device provided with at least a process equipment such as a photosensitive body 1, an electrostatic charging device 5, and a desticizing lamp 12 in a case 21; a projecting part 13 obtained by projecting one part of the case 21 is provided between the lamp 12 and the device 5, and the tip of the projecting part 13 is positioned nearer to the photosensitive body than the light emitting surface of the lamp 12. Therefore, light from the lamp 12 is shielded by the projecting part 13 of the case 21 and an electrostatic charging position is prevented from being irradiated with the light, so that the lowering of the electrostatic charging potential caused by the light of the destaticizing lamp is prevented and the good-quality image is secured.

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 used in copying machines, printers and the like.

[0002]

2. Description of the Related Art In recent years, there has been a strong demand for downsizing of electrophotographic image forming apparatuses such as copying machines and printers, and processes for image forming apparatus such as photoconductors, charging devices, transfer devices, cleaning devices, discharge lamps, etc. The device layout has been devised and these process devices have been unitized. As a photoconductor unit, process devices such as a photoconductor, a charging device, a transfer device, a cleaning device, and a discharge lamp are integrated. The process cartridge has been commercialized as a compact unit.

[0003]

However, in order to realize such compactness, the layout of each process equipment must be made difficult, and moreover, the space between the devices must be narrowed, and the space between the devices must be reduced. The current situation is that there is no room. For this reason, there is also a problem that the process equipments are too close to each other.In particular, when the static elimination lamp and the charging device are too close to each other, the target charging potential is not secured on the photoconductor due to the irradiation of the light from the static elimination lamp, and is lowered. There is a problem that it will end up. Particularly normal development scheme - the (positive positive mode), as shown in the photosensitive member surface potential model of Figure 2, the charge potential V _D
Since the image density is determined by the potential difference between the developing bias V _B and the developing bias V _B , the charging potential V _D is particularly important, and there is a problem that the influence of the decrease in the charging potential has a great influence on the image quality. The present invention has been made in view of the above circumstances, and prevents deterioration of the charging potential due to light irradiation of a static elimination lamp installed near the charging device, and a high-quality image even when the device is made compact or unitized. It is an object of the present invention to provide an image forming apparatus capable of ensuring the above.

[0004]

In order to achieve the above object, in the invention according to claim 1, an electrophotographic image forming apparatus is provided with at least a photosensitive member, a charging device, and process equipment such as a discharging lamp in a case. In the above, a part of the case is projected between the static elimination lamp and the charging device, and the tip of the case is located closer to the photoconductor than the light emitting surface of the static elimination lamp. According to the second aspect of the invention, in an electrophotographic image forming apparatus including at least a photoconductor, a charging device, and a process device such as a charge eliminating lamp, a casing of the charge eliminating device on the charge eliminating lamp side is projected toward the photoconductor side. The tip is located closer to the photoconductor than the light emitting surface of the static elimination lamp.

[0005]

According to the first aspect of the present invention, a part of the case is projected between the static elimination lamp and the charging device, and the tip of the case is located closer to the photoconductor than the light emitting surface of the static elimination lamp. By doing so, the light from the static elimination lamp is shielded by the case protrusion, and it is prevented from irradiating the charging position. According to the second aspect of the invention, the casing of the charging device on the side of the static elimination lamp is projected toward the photoconductor, and the tip of the casing is positioned closer to the photoconductor than the light emitting surface of the static elimination lamp. The projection of the casing of the device shields the light from the static elimination lamp and prevents it from being applied to the charging position.

[0006]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 shows a photoconductor unit (Photo Conductor Ma) of an image forming apparatus showing an embodiment of the present invention.
(gazine: PCM) is a schematic sectional configuration diagram. In FIG. 1, reference numeral 1 is a photosensitive belt, 2 is a driving roller for driving the photosensitive belt 1, 3 is a driven roller, and 4 is a pressure roller for stretching the photosensitive belt. Reference numeral 5 denotes a charging device that charges the photoconductor belt 1 to a predetermined negative (-) potential by a negative (-) corona discharge in the dark, to which a grid 6 is attached and which is fixed on the photoconductor belt 1. Has a function of giving a charging potential V _D of. Reference numeral 7 denotes an exposure from an exposure device (not shown). This exposure 7 is applied to a portion corresponding to a non-image portion (white portion) of the photosensitive belt 1 and the potential on the photosensitive member is expressed by the surface potential model of the photosensitive member in FIG. White part surface potential V _{L shown}
Drop to.

Numeral 8 is an eraser for removing the charging potential of the non-image portion, and normally, the front and rear ends of the image forming area of the photosensitive belt 1 and side erase are performed. A developing roller 9 of the developing device forms a visible image by adhering positive (+) toner to the electrostatic latent image on the photosensitive belt 1 to develop the electrostatic latent image. At this time, a bias voltage (V _B shown in FIG. 2) is applied to the sleeve of the developing roller, and as shown in FIG. 2, toner is charged by the photosensitive belt by the potential difference between the charging potential V _D and the developing bias V _B. Adhere on 1. Reference numeral 10 denotes a transfer device, which applies a negative (-) charge from the back surface of the transfer paper (paper) fed from a paper feed device (not shown) to transfer the toner on the photosensitive belt 1 to the transfer paper. The transfer paper after the toner transfer is sent to a fixing device (not shown) and fixed. 1
Reference numeral 1 denotes a cleaning device for scraping off and cleaning untransferred toner remaining on the photosensitive belt 1, and reference numeral 12 denotes a discharging lamp for removing a residual potential on the photosensitive belt 1.
In FIG. 1, the hatched portion of reference numeral 21 is the cross section of the PCM case of the photoconductor unit 20.

Here, FIG. 3 is a perspective view of an essential part of the photoconductor unit 20 shown in FIG. 1. As shown in FIGS. 1 and 3, the charging device 5 and the discharging lamp 12 both use the PCM case 21 as a guide. It is installed, and between these two, a PC
A rib 13 is provided which is formed by projecting a part of the M case 21 toward the photoconductor belt 1, and the tip of the rib is located closer to the photoconductor belt 1 than the light emitting surface of the static elimination lamp 12. .. That is, as shown in FIG.
And the distance between the surface of the photoconductor belt 1 and the surface of the photoconductor belt 1 is d ₁
When the distance between the light emitting surface of the sheet and the surface of the photoconductor belt 1 is d ₂ , by setting d ₁ <d ₂ , the static elimination lamp 12 irradiates the photoconductor belt 1 directly below the charging device 5. Light (broken line arrows A and B in the figure) is blocked by the ribs 13,
Irradiation of the charge removal lamp light to the charging position is prevented. Thus, it is possible to prevent the charging potential on the photosensitive belt 1 from decreasing. As shown in FIG. 4, when the distance between the grid 6 of the charging device 5 and the surface of the photosensitive belt 1 is d ₃ , naturally, d ₁ <d ₃ is set.

Next, an embodiment of the invention described in claim 2 will be described. FIG. 5 shows an example of a general charging device used in an image forming apparatus, in which 14 is a casing, 15 is a rear end block, 16 is a front end block, and 6 is a grid. The static elimination lamp side of the casing 14 of the charging device as shown in FIG. 5 is extended downward as shown by the hatched portion in FIG. 6 to provide a projecting portion 17, so that the projection portion 17 blocks the irradiation light from the static eliminating lamp. To That is, as in the embodiment shown in FIG.
The protrusion 17 is provided so as to extend to the side, and the tip of the protrusion 17 is positioned closer to the photoconductor than the light emitting surface of the static elimination lamp 12, thereby preventing irradiation of the static elimination lamp light to the charging position. Is. As a result, the same effect as that of the first aspect of the invention can be obtained. In the above embodiments, a belt-shaped photosensitive member is given as an example, but a drum-shaped photosensitive member can also be used. Further, the shapes of the photoconductor units and the like are not limited to those shown in the figures.

[0010]

As described above, according to the first aspect of the present invention, a part of the case is made to project between the charge eliminating lamp and the charging device, and the tip of the case is more exposed than the light emitting surface of the charge eliminating lamp. By being located near the body,
Light from the static elimination lamp is blocked by the protruding part of the case,
Since the irradiation to the charging position is prevented, it is possible to prevent the decrease of the charging potential due to the light of the discharging lamp. Therefore, it is possible to dispose the charge eliminating lamp and the charging device in close proximity to each other, and it is possible to make the image forming apparatus compact, and it is possible to secure a high-quality image even when the apparatus is made compact or unitized. .. In addition, claim 2
According to the invention described above, the casing of the charging device is arranged such that the casing on the side of the charge eliminating lamp is projected toward the photoconductor and the tip of the casing is positioned closer to the photoconductor than the light emitting surface of the charge eliminating lamp. Light from the discharge lamp is shielded by the protrusion and is prevented from being applied to the charging position, so that it is possible to prevent a decrease in the charging potential due to the discharge lamp light. Therefore, the charge eliminating lamp and the charging device can be arranged close to each other, the image forming apparatus can be made compact, and a high quality image can be secured even when the apparatus is made compact or unitized. ..

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional configuration diagram of a photoconductor unit of an image forming apparatus showing an embodiment of the invention according to claim 1.

FIG. 2 is a diagram showing a photoreceptor surface potential model in a regular development method (positive-positive method).

FIG. 3 is a perspective view of a main part of the photoconductor unit shown in FIG.

FIG. 4 is an explanatory diagram of the invention according to claim 1, and is a diagram showing a positional relationship of a rib tip, a discharge lamp emission surface, and a grid with respect to a photoconductor.

FIG. 5 is a perspective view showing an example of a general charging device used in an image forming apparatus.

FIG. 6 is a perspective view of a charging device showing an embodiment of the invention according to claim 2;

FIG. 7 is a perspective view of an essential part of a photoconductor unit showing an embodiment of the invention according to claim 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Photosensitive belt 2 ... Driving roller 3 ... Followed roller 4 ... Pressurizing roller 5 ... Charging device 6 ... Grid 8 ... Eraser 9 ... Developing roller 10 ... ..Transfer device 11 ... Cleaning device 12 ... Electrification removing lamp 13 ... Rib (protruding portion of case) 14 ... Casing of casing 17 ... Causing protruding portion 20 ... Photoconductor unit ( PCM) 21 ... PCM case

Claims (2)

[Claims] 1. An electrophotographic image forming apparatus comprising at least a photosensitive member, a charging device, and process devices such as a discharge lamp in a case, wherein a part of the case protrudes between the discharge lamp and the charging device, and An image forming apparatus characterized in that its tip is located closer to the photoconductor than the light emitting surface of the static elimination lamp. 2. In an electrophotographic image forming apparatus equipped with at least a photoconductor, a charging device, a static elimination lamp and other process equipment, the static elimination lamp side casing of the charging device projects toward the photoconductor side, and the tip thereof is the static elimination lamp. The image forming apparatus is located closer to the photoconductor than the light emitting surface of the.