JPH04175779A - Image forming device - Google Patents

Abstract

PURPOSE:To keep the interval between a photoreceptor drum and a developing roller to a proper value by bringing spacer rollers into contact with support members made of resin. CONSTITUTION:Spacer rollers 13b provided on both sides of the developing roller 13c of a developing unit are brought into contact with support members 2 on both sides of a photographic photoreceptor drum 11, not with the photoreceptor drum 11, to keep the interval between the developing roller 13c and the photoreceptor drum 11. A photosensitive layer is formed over the whole area on the outer periphery of the photoreceptor drum 11, and the whole area of the photoreceptor drum 11 except the formation area of an electrostatic latent image is electrified in reversal development. The support members 2 are made of resin, and the support members 2 are electrified. A toner can be prevented from being stuck to the vicinity of both end sections of the photoreceptor drum 11 and the support members 2. The fluctuation of the distance between the photoreceptor drum 11 and the developing roller 13c can be prevented.

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to an image forming device installed in an image forming apparatus such as a copying machine, a facsimile machine, a laser beam printer, or the like. <Prior Art> Conventionally, in the above-mentioned image forming apparatus, an electrostatic latent image formed on a photoreceptor drum is developed into a toner image by a developing device, and then the electrostatic latent image is transferred to paper. Equipped with a system imaging device. In the above-mentioned image forming apparatus, a developing roller that is disposed opposite to the photosensitive drum at a predetermined distance is generally used as a means for developing the electrostatic latent image into a toner image. This developing roller holds developer containing toner, and
The developer is supplied to the photosensitive drum by rotating it in accordance with the rotation of the photosensitive drum, thereby visualizing the electrostatic latent image using toner. In the image forming device using the above-described developing roller, if the distance between the photosensitive drum and the developing roller changes, the amount of developer supplied to the photosensitive drum changes, causing image defects such as density unevenness in the formed image. Since there is a possibility that this may occur, it is necessary to always maintain a constant distance between the two. means for keeping the distance between the developing roller and the photosensitive drum constant;

For example, as shown in FIG. 4, a spacer roller 93 is used which is arranged coaxially with the developing roller 9]- and comes into contact with the surface 1 of the photosensitive tram 92. This spacer roller 93 has a diameter slightly larger than that of the developing n-roller 91, and the distance between the photosensitive drum 92 and the developing roller 91 is equal to half the difference in diameter by 8 [1]. It is something to keep. The photoreceptor Torano 292 has a photosensitive layer laminated on the surface of an aluminum cableway in order to form an electrostatic latent image.
Due to rolling contact and friction with the spacer roller 93,
Is it a photosensitive layer? In order to prevent IJH, normally, as shown in the figure, a roller abutting part 92b on which a photosensitive layer is not formed is provided adjacent to a photosensitive part 92a on which a photosensitive layer is formed. A spacer roller 93 is attached to the roller contact portion 92b.
(-) so that they come into contact with each other. Therefore, in the roller contact portion 92b, the surface of the raw tube or a base layer (for example, a metal oxide treatment layer) formed as necessary between the photosensitive layer and the raw tube is exposed. It becomes. <Problem to be solved by the invention> In the photoconductor tram 92, the roller contact portion 92b or
In the case of aluminum tubes, during reversal development,
Since the roller contact portion 92b is not main charged and has a potential of approximately zero, toner floating around it or attached to the roller contact portion 92b causes the photosensitive drum 92 and the developing roller 91 There have been problems in that the distance between the image forming apparatus and the image forming apparatus may fluctuate, or the adhered toner may scatter and stain the inside of the image forming apparatus. In addition, if the roller contact portion 92b is a base layer, toner adhesion may be reduced due to its insulating properties, or the base layer may be worn out due to rolling contact with the spacer roller 93, causing the inside of the image forming apparatus to be damaged. There was also the problem of it being defaced. This invention has been made in view of the above-mentioned problems, and it is possible to prevent the inside of an image forming apparatus from being soiled, and also to accurately maintain the distance between the photosensitive drum and the developing row. The purpose of the present invention is to provide an image forming device that can perform the following functions. Means for Solving the Problems> In order to achieve the above object, the image forming apparatus of the present invention is provided with spacer rollers on both sides of the developing roller of the developing device, and the spacer rollers are connected to resin supporting both sides of the photoreceptor drum. The developing roller is brought into contact with a support member made of aluminum to maintain the distance between the developing roller and the photosensitive drum 1', and a photosensitive layer is formed over the entire outer circumferential surface of the photosensitive drum. It is. According to the image forming apparatus having the above configuration, the spacer rollers provided on both sides of the developing roller of the developing device are brought into contact with the support members on both sides of the photoreceptor drum instead of the photoreceptor drum. Since the distance between the roller and the photoreceptor drum is maintained and the photoreceptor layer is formed over the entire outer peripheral surface of the photoreceptor drum, the electrostatic latent image forming area of the photoreceptor drum is formed during reversal development. The entire area excluding the area will be charged. Further, since the support member is made of resin, the support member is also charged. Therefore, it is possible to prevent toner from adhering to the vicinity of both ends of the photoreceptor drum and to the support member. Therefore, it is possible to prevent the toner that has landed on the photoreceptor drum from scattering or the distance between the photoreceptor tram and the developing roller to fluctuate due to the toner that has landed on the photoreceptor drum. <Embodiments> Hereinafter, embodiments will be described in detail with reference to the accompanying drawings showing embodiments. FIG. 3 is a schematic diagram showing an image forming section 1 of a copying machine as an image forming apparatus to which the present invention is applied. In this image forming section 1, a charging charger 12, a developing device 13, a transfer charger 14, a separation charger 15, and a cleaning device]6 are arranged in this order around a photosensitive drum 11 that rotates in the direction indicated by arrow X in the figure. After forming an electrostatic latent image by forming an image of the document on the photosensitive drum 11 which is arranged and uniformly charged by the charging charger 12,
The developing device 13 visualizes the toner image, the transfer charger] 4 transfers the toner image onto the paper P, and the cleaning device 16 collects the remaining toner. As shown in FIG. 1, the photosensitive drum 11 is supported by a drum shaft 41 via flange-shaped support members 2.degree. 3 fitted to both ends thereof. This photosensitive drum 1
] is a cylindrical tube made of metal such as aluminum 1 l
The photosensitive layers], ], and c are formed on the outer circumferential surface of the photoreceptor drum. The four drum shafts are installed between a pair of side plates 43 provided on the main body of the copying machine, and the support members 2 and 3 are rotatably held with respect to the drum shaft 41 via bearings 42. has been done. Of the support members 2 and 3, the support member 2, which is disposed on the inner back side of the copying machine main body, is rotationally driven by a drum motor M, and the drive torque is applied to the photoreceptor drum 11.
to communicate. As shown in FIG. 2, the supporting member 2 has a fitting part 2 which fits the inner periphery of the end of the photoreceptor drum 11, and an annular friction member that aligns one end surface 11a of the photoreceptor drum 1. Part 2
2, an annular pressing portion 23 and a gear 24 connected to the fitting portion 21. The above-mentioned fitting portion 2] is formed to have an outer diameter large enough to allow the photoreceptor drum 11 to be removably fitted therein, and the outer periphery of the tip end thereof has a groove for guiding the fitting of the photoreceptor tram 11. Taber surface 2 ], a is formed. Further, the friction member 22 is made of an elastic material such as rubber, and for example, an O-ring is used. The friction member 22 is pressed against one end surface 1 of the photoreceptor drum 11 while being relatively pressed by the pressing portion 23 . ], is pressed against a. Further, the pressing portion 23 is finished so that its outer peripheral surface is concentric with the outer peripheral surface of the photoreceptor drum 11.
3 is formed with a protrusion 25 that bites into the friction member 22 to restrict slippage between the friction member 22 and the pressing portion 23 . This locking protrusion 25
For example, the supporting member 2, except for the friction member 22, is integrally molded from resin. The gear 24 is meshed with a drive gear M2 fixed to a motor shaft M of the drum motor M.Furthermore, the other support member 3 has an annular roller that comes into contact with a spacer roller 3f, which will be described later. A contact portion 31 is formed.This roller contact portion 31 is also finished so that its outer peripheral surface is concentric with the outer peripheral surface of the photoreceptor drum 1.The developing device 13 is shown in FIG. As shown, a casing 13a containing a developer therein, and a casing 1.3a
A developing roller 13c is rotatably arranged facing the opening 13b of the casing 13a, and an agitating side 1.3 for stirring the developer is rotatably arranged inside the casing 13a.
d, and a toner hopper 13e disposed above the stirring side 13d for replenishing toner consumed during image formation. Further, on both sides of the developing roller 1.3c, a pair of spacer rollers 13f are provided coaxially with the developing roller 13c, as shown in FIG. One of the spacer rollers 13f is in contact with the outer peripheral surface of the pressing portion 23 of the support member 2, and the other spacer roller 13f is in contact with the roller contact portion 31 of the support member 3. , photoreceptor tram 1] and the developing roller 13c are maintained at an appropriate distance. In this way, in the above image forming device, the spacer roller 1
Since the photosensitive layers 11 and 3f are in contact with the supporting members 2 and 3 and are formed over the entire outer periphery of the photosensitive drum 1, the electrostatic latent of the photosensitive drum 1 is reduced during reversal development. The entire area except the image forming area is charged, and the toner floating near both ends of the photoreceptor tram 1]
It is possible to prevent the adhesive from adhering to the vicinity of both ends. In addition, since the support member 2 is made of resin, this support member 2
There is no possibility that floating toner will adhere to the supporting member 2 as a result of being charged. Therefore, it is possible to prevent the toner adhering to the photoreceptor drum 11- from scattering and to prevent the distance between the photoreceptor tram 11 and the developing roller 13C from changing due to the adhesion of toner. Furthermore, according to the support member 2, the driving force of the tram motor M is applied to the photoreceptor drum 1 through the annular friction member 22.
1, and during this transmission, the friction member 22 is pressed against the one end surface 1.1a of the photoreceptor tram 1, so that the friction member 22 is made of an elastic material. Together, it is possible to obtain a good frictional force between the one end surface 1 and a. Therefore, torque transmission to the photoreceptor drum 11 can be ensured. However, the locking protrusion 25 formed on one side of the pressing part 23 allows the pressing part 23 and the friction member 22 to be connected to each other.
Between -C slip force! Since this can be prevented, the torque transmission described above can be carried out even more reliably. When the photoreceptor drum 11 is attached to the copying machine main body, one end of the photoreceptor tram 1 is fitted into the fitting portion 21 of the support member 2, and the photoreceptor drum 11 is It can be supported by the support member 2 so that torque can be transmitted. In this way, when mounting the photoreceptor drum 1, it is not necessary to align the photoreceptor tram 11 and the support member 2 in the circumferential direction, so that the mounting operation can be performed easily and quickly. In this regard, conventionally,
■ By engaging an engaging part such as a notch or protrusion formed at the end of the photoreceptor drum with a predetermined part on the support member side,
91 times the l-lux transmission (for example,
1. , No. 76873), Q) By pressing the taper on the support member side against the taper formed on the inner periphery of the end of the photoreceptor drum, torque can be transmitted (for example, in practical applications). (Refer to Publication No. 1.76873), and according to the support member in (1) above, press working, cutting work, etc. are required to form the engaging part at the end of the photoreceptor drum. , there is a problem that the photoreceptor drum is distorted during the processing, which adversely affects the formed image, and when the photoreceptor drum is attached to the main body of the image forming apparatus, the engaging portion and the support member are not engaged. In order to do this, it is necessary to manually align the photoreceptor drum and the support member in the circumferential direction, which poses a problem in that alignment is difficult and the mounting process is time-consuming. In addition, according to the holding member (2) above, torque is transmitted by frictional force, so in order to easily prevent slippage and ensure torque transmission, the cylindrical tube constituting the photoreceptor tram must be Is it necessary to increase the wall thickness of the drum to widen the contact area between the tab and the roller?As the wall thickness increases, the cost of materials for the photoreceptor drum increases, and it is also necessary to finish the tab with high precision. Because of this, there was a problem that manufacturing costs were even higher. However, according to the support member 2,
It is possible to solve these problems all at once. Note that the image forming apparatus of the present invention is not limited to the above-mentioned embodiment, and for example, regarding the support member 2, the suppressing portion 2
Separately from 3, an annular roller abutting part is provided, and the spacer roller], 3 f is brought into contact with this roller abutting part, and the support member 2
The support member 2 is held rotatably with respect to the drum shaft 4], and the supporting member 2 is rotated by driving the drum shaft 4], and the locking convex portion 25 is formed into a microscopic protrusion. Various design changes can be made, such as configuring it by In addition, in the above embodiment, the case where the present invention is applied to a copying machine, a facsimile machine, a facsimile machine,
Of course, the present invention can also be applied to other image forming apparatuses such as laser beam printers. <Effects of the Invention> As described above, according to the image forming apparatus of the present invention, by holding the spacer roller in contact with the support member made of resin, the distance between the photoreceptor drum and the developing port can be adjusted appropriately. In addition, since the photosensitive layer is formed over the entire outer circumference of the photosensitive drum, during reversal development, the entire area of the photosensitive drum excluding the electrostatic latent image formation area and the support member are charged. By doing so, it is possible to prevent toner floating near both ends of the photoreceptor tram from adhering to the vicinity of both ends and the support member. Therefore, it is possible to prevent the torch attached to the photoreceptor drum from scattering and staining the inside of the image forming apparatus, and to prevent the distance between the photoreceptor drum and the developing roller from changing due to toner adhesion. It has the unique effect of being able to

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a partially cut-out plan view showing an embodiment of the support member of the present invention, FIG. 2 is a perspective view of the support member, FIG. 3 is a schematic diagram of the image forming section, FIG. 4 is a schematic diagram showing a conventional example. ]]...Photoreceptor drum, 13...Developer, 1, 3 c...
-Developing roller, 13f -Spacer roller, 2...Supporting member.

Claims (1)

[Claims] 1. In an image forming device that develops an electrostatic latent image formed on the surface of a photoreceptor drum into a toner image using a developing device and then transfers the toner image onto paper, spacer rollers are installed on both sides of the developing roller of the developing device. The spacer rollers are brought into contact with resin support members that support both sides of the photoreceptor drum, thereby maintaining the distance between the developing roller and the photoreceptor drum, and maintaining the distance between the outer peripheral surface of the photoreceptor drum. An image forming device characterized in that a photosensitive layer is formed over the entire area.