JPH04110873A - Image formation device - Google Patents

Abstract

PURPOSE:To prevent light beams from other light sources from interferring, and to easily form a sharp image without disordering a latent image carried on a photosensitive body by arranging an exposing means and an electrostatic discharging means in a photosensitive body across a light shield means. CONSTITUTION:The exposure unit 2 in the photosensitive drum 1 is arranged fixedly on a bases 21 made of an opaque insulating material and an eraser 24 is also arranged and fixed at the circumference-directional opposite position across an LED array 22, a self-converging lens 23, an exposure system, and the base 21 while they are extended over the entire area in the direction of the photosensitive body axis. The base 21 consists of a T-shaped support plate 21a which divides the eraser 24 and empty areas 26a and fixing a wiring board 28 fitted with the LED array 22 and the condenser lens 23, and they are formed of opaque insulating materials; and the eraser 24 and exposure system are shielded from each other by the T-shaped support plate 21 and the exposure system is shielded by the couple of support plates 21b and 21c, so the light of the eraser 24 never causes interference at the time of exposure to enable exposure and image formation with high sharpness.

Description

Detailed Description of the Invention "Industrial Application Field" The present invention relates to a drum-shaped or belt-shaped photoreceptor (hereinafter referred to as both The present invention relates to an image forming apparatus in which an exposure means for forming an image is disposed on the inner peripheral side of an endless photoreceptor.

"Prior Art" Conventionally, exposure means generates light output corresponding to image information on the inner peripheral side of a photoreceptor drum, which is formed by laminating a light-transmitting conductive layer and a photoconductor layer on a light-transmitting support. At the same time or immediately after focusing the light output of the exposure means to form a latent image on the photoconductive layer, the latent image is made visible through a developing means disposed facing the photosensitive drum. 2. Description of the Related Art Image forming apparatuses are known that are configured to be able to transfer the toner image onto plain paper via a transfer roller or other transfer means after forming an image (toner image). (Japanese Unexamined Patent Publication No. 58-153957, etc.) In this type of image forming apparatus, an eraser or other charge eliminating light source is installed in the photoreceptor drum in order to remove the charge remaining on the surface of the photoreceptor after the transfer. A technique has been disclosed in which the residual charge is removed between the transfer position and the exposure position, thereby making it possible to form a clear latent image at the exposure position. (Unexamined Japanese Patent Publication No. 6
2-136668) ``Technical Problems to be Solved by the InventionJ'' And in the prior art, the exposure means and the static elimination light source are arranged on a rotating shaft that rotatably supports the photosensitive drum via a bearing. Because multiple light sources are inserted along the axial direction inside the photoreceptor drum in order to remove static electricity, the light from the other light sources interferes with each other, especially in the area from the exposure position to the transfer position. If leakage occurs, the latent image carried on the photoconductor layer will be disturbed, making it difficult to form a clear image.

In view of the drawbacks of the prior art, the present invention prevents the light from the other light sources from interfering with each other even when a plurality of light sources for exposure and charge removal are arranged inside the photoreceptor drum. It is an object of the present invention to provide an image forming apparatus that can easily form a clear image without causing disturbance in a latent image.

"Technical Means for Solving the Problem" In order to achieve the technical problem, the first invention provides a light shielding device that extends in the photoreceptor along a direction perpendicular to the rotational direction, as shown in the embodiments described later. The present invention is characterized in that the exposure means and the static elimination means are disposed within the photoreceptor with the light shielding means interposed therebetween.

Such a light shielding means may include a flat band-shaped member inserted into the photoreceptor, and the exposing means and the static eliminating means may be arranged back to back on both sides of the photoreceptor, but it is particularly preferable to If light leakage occurs in the static eliminating means on the photoreceptor in the area leading to the transfer position, the image is likely to be greatly disturbed.
By providing a light-shielding portion disposed not only on the back-to-back side but also on the upstream side in the circumferential direction of the photoreceptor drum of the static eliminating means, exposure to the transfer position side can be substantially completely blocked.

In this case, by integrally assembling the exposure means and the static elimination means on the light shielding means to form a unit, it becomes easy to replace and take out the unit, and in particular, the unit body can be placed inside the endless photoreceptor without contact. By being configured so that it can be inserted in the same state, there is no risk of damaging the peripheral surface of the photoreceptor when replacing the unit body, and there is no risk of cutting lead wires etc. attached to the exposure means when inserting and removing the unit. .

"Embodiments" Hereinafter, embodiments of the present invention will be described in detail by way of example based on the drawings. However, unless otherwise specified, the dimensions, materials, shapes, and relative positions of the components described in this example are not intended to limit the scope of this invention, but are merely illustrative examples. Not too much.

FIG. 1 shows the overall structure of an image forming apparatus according to an embodiment of the present invention, in which 1 is a photoreceptor drum, and a drum-shaped light-transmitting support la is provided with a light-transmitting conductive layer 1b and a photoconductor layer IC. It is formed by laminating layers, and is configured to be rotatable in the direction of the arrow by a drive roller 11, which will be described later.

2 is an exposure unit inserted into the photoreceptor drum;
As will be explained in detail later, an LED that generates light output corresponding to image information is mounted on a support 21 made of a non-transparent insulating material.
An exposure system consisting of bibundle lenses 23 (trade name: SELFOC lenses) on two rows, and an eraser 24 on the opposite side in the circumferential direction with the support 21 in between, are installed over the entire axial direction of the photoreceptor. It is extended and fixedly arranged. The image forming position of the exposure system is configured to form an image on the photoconductor layer 1c located on a line connecting the axes of the photosensitive drum 1 and the developing sleeve 31 (hereinafter referred to as the focal line).

Reference numeral 3 denotes a developing device, which has a toner container 32 containing conductive magnetic toner with an opening on the side facing the photosensitive drum 1, and a developing sleeve 3 which includes a fixed magnet assembly 34 in the opening 33.
1, and by rotating the sleeve 31 in the direction of the arrow, the toner whose layer thickness is regulated by the doctor blade 36 formed on the side of the container 32 is guided to the development position corresponding to the image formation position of the exposure system. After developing the latent image formed on the development position, the toner image carried on the photosensitive drum 1 is guided to the transfer roller 4 side according to the rotation of the drum 1, and is transferred by the transfer roller 4 to the registration roller 5. After being transferred onto the inserted plain paper at the appropriate timing, the transferred unfixed toner image is fixed by a fixing roller 6 and then discharged onto a paper discharge tray 7.

On the other hand, after the toner transfer, the photoreceptor drum 1 is erased by an eraser 2.
After being neutralized in step 4, the toner is led to the developing position again, and the residual toner is removed by rubbing against the toner just before the developing position, and the above operation is repeated.

Note that 8 is a paper feed roller that guides the plain paper stacked in the paper feed cassette 9 to the registration rollers 5.

Now, the exposure unit 2, which is the gist of the present invention, will be explained in detail based on FIG.
, a self-focusing lens 23 exposure system, and an eraser 24 at a position on the opposite side in the circumferential direction of the support body 21, extending over the entire axial direction of the photoreceptor, and fixedly disposed therein. An insulating cover member 25 having a semicircular arc cross section is attached to cover the outer peripheral side of the support body 21 located between the self-focusing lens 24 and the self-focusing lens 23, and the cover member 25 and the support body 21 create two divided air spaces 26a. , 26b (5) A group of lead wires 27 for connecting the LED array 22 and the eraser 24 are housed in the divided air spaces 26a and 26b.

Further, the support body 21 includes the eraser 24 and the air space 26a,
A T-shaped support plate 21a that divides 26b, and the LED
It consists of a wiring board 28 to which the row 22 is attached and a pair of support plates 21b and 21c that sandwich and fix the focusing lens 23, and as described above, these are made of a non-transparent insulating material and are connected between the eraser 24 and the exposure system. is shielded in the circumferential direction by the T-shaped support 21, and the exposure system is surrounded by a pair of supports 21b,
Since it is hidden by the 21c plate, the eraser 2
The light of 4 does not interfere with each other during exposure, making it possible to form an exposure image with high clarity.

That is, more specifically, since the eraser is attached to the one side wall surface of the T-shaped support plate 21a, in other words, the upstream side in the circumferential direction of the eraser is formed by the double wall surface and the cover member. Since it is completely shielded, there is no risk of light leakage to the transfer position side.

Further, the lead wire 27 is also connected to the air space 26 surrounded by the insulating member.
Since the lead wire 27 is concealed and housed in the photoreceptor drum 1, the risk of the lead wire 27 being accidentally contacted and broken when the exposure unit 2 is inserted into or removed from the photoreceptor drum 1 is eliminated. As shown in FIG. 3, the photosensitive drum 1 is extended to both ends in the axial direction beyond the image forming area, and ring-shaped spacers 28 are interposed at both ends of the extended area. It is inserted into the inner circumferential surface of the drum 1 at a distance therebetween.

The outer diameter of the spacer 28 is set to be the same as or slightly smaller than the inner diameter of the photosensitive drum 1, and in order to function as a bearing when the drum 1 rotates, the bearing is constructed using a bearing or the like. However, since it is inconvenient to use a bearing in order to make the unit 2 removable, it is formed using a fluororesin or other low-sliding, self-lubricating material.

The unit 2 is fixed to a position fixing plate 43 which is fixed to a housing 41 with a screw 42 via a central shaft 29, and one side of the housing 41 is opened from the inner diameter of the photoreceptor drum 1. The unit 2 is configured to be able to be extracted from the opening alone or together with the drum 1.

As a result, by removing the screws 42 of the position fixing plate 43, the exposure unit 2 can be pulled out in the direction of the axis 29 and reloaded while its position is restricted by the spacer 28. scrubs the inner circumferential surface of the photoreceptor drum, making cleaning possible.

On the other hand, as shown in FIG. The photoreceptor drum 1 is rotatably supported while maintaining the gap with the developing sleeve 31 with high accuracy by being supported at three points by the roller 11.The drive roller 11 drives the motor shaft gear 15. Relay gear train +6
It is configured to be able to rotate synchronously with the transfer roller 4 via a. The transfer roller 4 is pressed against the photosensitive drum by a spring J7.

Therefore, even if the exposure unit 2 is inserted or removed, the photosensitive drum 1 is always positioned and held at a predetermined position.

Note that the swing roller 11 may be configured to be fixed to a lever member 19 that is biased by a click-clack spring 18, so that by rotating the lever member 19 in the direction of the arrow, With the lever member 19 fixed in a downward position, the pressure contact of the photoreceptor drum 1 can be released, and by this release, the photoreceptor drum 1 can be taken out together with the exposure unit. preferable.

Incidentally, IA is an annular sleeve concentrically provided around the outer periphery of the photosensitive drum l that comes into contact with the lever member 19.

"Effects of the Invention" As described above, according to the present invention, even if a plurality of light sources for exposure and static elimination are arranged inside a photoreceptor, light from other light sources can be prevented from interfering with each other, and the light can be carried on the photoreceptor. It has various remarkable effects such as making it possible to easily form a clear image without causing any disturbance in the latent image formed.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is an overall configuration diagram of an image forming apparatus according to an embodiment of the present invention, FIG. 2 is a sectional view of an exposure unit incorporated in the apparatus, and FIG. 3 is a diagram showing the assembly of the exposure unit. FIG. 4 is a side view showing the state in which the photoreceptor drum is attached, and FIG. 4 is an operational view of the drive system showing the state in which the photoreceptor drum is supported.

Claims (1)

[Claims] 1) A layer for forming a latent image on the inner circumferential side of an endless photoreceptor formed by laminating a light-transmitting conductive layer and a photoconductor layer on a light-transmitting support, with the transfer position in between. In an image forming apparatus equipped with an exposure means and a charge eliminating means for removing residual charges after transfer, a light shielding means is provided inside the photoreceptor and extends along a direction perpendicular to a rotating direction of the photoreceptor; An image forming apparatus characterized in that the exposure means and the static elimination means are disposed in a photoreceptor body. 2) The light shielding means includes a light shielding portion disposed upstream of the static elimination means in the circumferential direction of the photoreceptor drum in order to prevent light leakage in the static elimination means in the area from the exposure position to the transfer position. The image forming apparatus according to claim 1). 3) Claim 1) wherein the exposing means and the static eliminating means are integrally assembled on the light shielding means to form a unit, and the unit body can be inserted into the endless photoreceptor in a non-contact manner. The image forming apparatus described above.