JPH0695236B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] In an image forming apparatus in which a toner developing unit and an image exposing unit are arranged to face each other through a transparent endless belt-shaped photoreceptor,
A transparent member that guides the endless belt-shaped photoconductor so as to pass through a predetermined path is provided between the endless belt-shaped photoconductor and the image exposure unit to prevent image blurring, density unevenness, fog, and the like. I did it.

[Industrial application field]

The present invention relates to an image forming apparatus that forms a toner image at the same time as image exposure on a photoconductor to display or transfer the toner image.

The current image recording apparatus generally uses an electrophotographic recording method, and image recording is performed in the steps of charging, exposing, developing, transferring, cleaning and the like. Since this recording method is charged by corona discharge, there are problems that ozone and odor that are harmful to the human body are generated, electrical noise is generated due to discharge, and reliability is reduced due to dust and the like.

Therefore, a method has been proposed in which image recording and display are performed without using corona discharge.

[Conventional technology]

FIG. 9 is a diagram showing a schematic configuration of a conventional image forming apparatus.

Reference numeral 111 denotes an endless photosensitive belt, which is composed of a transparent substrate, a transparent conductive layer, and a photoconductive layer in this order from the inside, and the transparent conductive layer is connected to the ground.

Reference numeral 113 is a magnetic brush developing machine in which a magnet roller 113b provided inside the sleeve 113a is freely rotatable. A recording electrode 115 insulated with a polyimide film 114 is attached to the surface of the magnetic brush developing machine 113. A voltage 116 having a polarity opposite to the carrier polarity of the photoconductive layer of the photoconductor 111 is applied to the recording electrode 115, and further, the recording electrode 1 is applied to the sleeve 113a.
A voltage 117 having a polarity opposite to that of 15 and the voltage 116 is applied. The developer is
The one-component or two-component toner 118 is used, and the toner 118 is conveyed by the magnet roller 113b.

An LED array is provided on the transparent substrate side (inside the belt) of the photoconductor 111.
Image exposure means 119 including 119a and SELFOC lens 119b
Are provided and are arranged so that the optical axis intersects with the recording electrode 115.

In the apparatus having the above-described structure, the toner image 120 is formed on the photoconductor 111 by moving the photoconductor 111 and the toner 118 in the direction of the arrow in the figure and performing image exposure using the image exposure means 119. Next, the image forming process of the conventional image forming apparatus will be described with reference to FIG. In FIG. 10, the same parts as those in FIG. 9 are designated by the same reference numerals.

In the figure, when the photoconductive layer 111c is imagewise exposed in the area A, photocarriers are generated in the photoconductive layer 111c. Among the photocarriers, carriers having a polarity opposite to the applied voltage 116 of the recording electrode 115 move to the vicinity of the surface of the photoconductive layer 111c and become latent image charges (plus in the figure). As described above, since the electrostatic capacity of the photoconductive layer 111c apparently increases in the exposed portion, the amount of adhered toner increases, and a toner image with a certain degree of contrast is formed between the exposed portion and the non-exposed portion.

Next, at part B, there is a pool of developer that was created by moving in the direction of the arrow, and when passing through this pool, the sleeve
Since the reverse voltage 117 is applied to 113a, the excess toner in the non-exposed portion is collected by the developing device 113 by electrostatic force.
At this time, the toner in the exposed portion is also slightly recovered, but most of the toner remains on the photoconductor 111 due to the electrostatic binding force of the latent image charge and the toner charge, and the toner image 120 is formed.

After that, the toner image 120 is electrostatically transferred onto the recording paper 121 by using the transfer roller 122 as shown in FIG. The transferred toner image 124 is fixed on the recording paper 121 by the fixing device 125, and a semi-permanent recorded image 126 is obtained.

On the other hand, the residual toner 127 that has not been transferred is removed by the static elimination light source 128.
The static electricity is not removed by the static electricity, and it is recovered by the magnetic force of the developing machine 113 and reused.

[Problems to be Solved by the Invention]

In the image forming apparatus described above, the exposure unit and the developing unit are required to have high positional accuracy. The position accuracy of the exposure part depends on the aperture angle of the SELFOC lens array used and the resolution of the image.
°, if the image resolution is 240 (dots / inch),
Position accuracy of about ± 0.1 mm is required. Also, the distance between the developing section and the photoconductor belt varies depending on the characteristics of the developer, but 0.3 to 0.5 mm is appropriate.Below this distance, the photoconductor belt may contact the recording electrode and scratch the photoconductor. If the distance is longer than this, there is no potential difference between the photosensitive belt, the recording electrode and the sleeve during image formation, and the image remains with toner adhered to the non-exposed portion.
Therefore, the positional accuracy of the developing unit is also required to be on the order of 0.1 mm.

However, in the above-described image forming apparatus, the photosensitive belt is stretched by the tension of the supporting roller (no contact portion) between the exposure portion and the developing portion, so that the exposure portion is not exposed to the photosensitive belt. It is difficult to set the position of the developing unit, and even after the setting, the position of the photoconductor belt may be displaced by 0.1 mm or more due to contact with the toner.Therefore, there is a problem that the image is blurred, uneven density or fog occurs. It was

Furthermore, in the exposure unit with the conventional configuration, both sides of the photoconductor belt are open, so minute dust and toner scattered from the development unit easily enter the exposure unit and adhere to the LED array and SELFOC lens array. Then, there is a problem that the image is missing.

Furthermore, since the LED array used in the exposure unit heats up considerably, if a cooling fan is attached, the belt will vibrate and the image will deteriorate in the conventional configuration, or the cooling air will diffuse inside the belt and cooling efficiency will increase. There was a problem of lowering.

For this reason, use a rotating drum-shaped photoconductor,
It has also been considered to increase the rigidity of the photoconductor. However, the transparent base of the photoconductor must be composed of a transparent member. There are glass and acrylic transparent bases, but it is difficult to accurately manufacture the glass into a cylindrical shape, which increases the cost. However, acrylic has a problem that it cannot withstand the heat of vapor deposition of the conductive layer and cannot be used for manufacturing.

[Means for solving problems]

FIG. 1 is a diagram for explaining the principle of the image forming apparatus according to the present invention. In the figure, reference numeral 1 is an endless belt-shaped photoreceptor, which is formed by sequentially laminating a transparent or semitransparent conductive layer 1b and a photoconductive layer 1c on a transparent substrate 1a formed in an endless belt shape, and 2 is a toner. A developing means, which is provided on the photoconductive layer 1c side of the endless belt-shaped photoreceptor 1, supplies toner 2a onto the endless belt-shaped photoreceptor 1, 3 is an image exposing means, What is provided on the transparent substrate 1a side and emits light according to the image to be formed to irradiate the transparent substrate 1a, 4 is a guide member, which is in contact with the transparent substrate 1a side,
The endless belt-shaped photoconductor 1 is guided so as to pass through a predetermined path, and at least the optical axis 3a of the image exposure means 3
The portion that intersects with is composed of a transparent member 4a.

[Action]

In the structure described above, the endless belt-shaped photoconductor is supported by the guide member 4 so as to pass through a predetermined path, so that the position is not displaced, and the image is blurred, the density is uneven, or the fog is generated. Nor.

〔Example〕

(A) Description of an Embodiment FIG. 2 is a schematic configuration diagram for explaining an embodiment of an image forming apparatus according to the present invention.

In the figure, 11 is an endless photosensitive belt. Photoconductor belt
As shown in FIG. 3, the structure of 11 is such that a transparent conductive layer 21b of ITO (indium oxide) vapor deposition film is provided on a transparent substrate 11a of polyethylene terephthalate having a thickness of 100 μm, and further, as a photoconductive layer 11c, CGL (charge A function-separated photoconductive layer made of an organic material composed of a generation layer) 11d and a CTL (charge transport layer) 11e is provided. A phthalocyanine-based material is used for the charge generation layer CGL and an oxazole-based material is used for the charge transport layer CTL, and both are thin and have a thickness of 10 μm. Transparent conductive layer
11b is connected to earth. The photoreceptor belt 11
In addition to the above configuration, the configuration may be such that an insulating layer is further provided on the photoconductive layer 11c.

The insulating layer is provided to prevent the charge in the photoconductive layer 11c and the charge in the toner from being neutralized and the electrostatic force not to be lost, and also to improve the durability.

The photoconductor belt 11 is stretched around the support roller 12 with a certain tension, and is conveyed by the support roller connected to the drive system.

Reference numeral 13 is a magnetic brush developing machine in which a cylindrical sleeve 13a made of a non-magnetic material and a magnet roller 13b are rotatably provided inside the sleeve 13a. A recording electrode 15 insulated with a polyimide film 14 is attached to the surface of the sleeve 13a of the magnetic brush developing machine 13. Since the photoconductive layer 11c of this embodiment is a hole transfer type, a negative voltage 16 of reverse polarity is applied to the recording electrode 15. This voltage is about -100 to -500V, preferably -150 to -300V. Further, the voltage 16 of the recording electrode 15 is applied to the sleeve 13a.
A positive voltage 17 having the opposite polarity of is applied. This voltage 17 is 0
About + 50V is preferable, and +10 to + 30V is suitable. A conductive magnetic toner 18 is used as the developer, and the toner 18 is conveyed by the magnet roller 13b. In addition to the conductive magnetic toner, the developer may be a mixed two-component toner in which the conductive magnetic toner is used as a carrier and the insulating magnetic toner is used as the toner.

An LED array optical system 19 composed of an LED array 19a and a SELFOC lens array 19b is provided as an image exposure means at a position facing the recording electrode 15 with the photoconductor belt 11 interposed therebetween. As shown in FIG. 4, a transparent plate 30 serving as a conveyance guide is provided inside the photosensitive belt 11. The position of the LED array optical system 19 is set so that an image is formed on the surface of the transparent plate 30 on the side in contact with the photosensitive belt 11.

Reference numeral 20 is a toner image on the photoconductor film 11. Reference numeral 21 is a recording paper, and 22 is a transfer conductive rubber roller, which is pressed against the photosensitive belt with a constant pressure. Reference numeral 23 is a power source for applying a voltage to the transfer roller 22. Reference numeral 24 is a toner image electrostatically transferred onto the recording paper 21, 25 is a thermal fixing device, and 26 is a semi-permanently recorded image.

27 is the residual toner remaining on the photoconductor belt after the transfer. Reference numeral 28 is a charge eliminating light source for removing the charge of the residual toner 27 and the latent image charge in the photoconductive layer. Reference numeral 29 is a toner image that has been neutralized and has lost its electrostatic restraint force.

Next, an image recording procedure will be shown.

The photosensitive belt 11 is rotated in the direction of the arrow, the magnet roller 13b of the developing machine 13 is rotated, and the toner 18 is conveyed in the direction of the arrow to form a toner pool in the developing area, and a voltage is applied to the recording electrode 15 and the sleeve 13b. LED array optics 19 in the state
Image exposure with. Photocarriers are generated in the CGL 11d, and holes in the photocarriers move inside the CTL 11e in the vicinity of the surface of the photoconductor to become latent image charges. In this way, in the exposed portion, the electrostatic capacity of the photoconductive layer 11c apparently increases, so that the amount of adhered toner increases and a toner image with a certain degree of contrast is formed between the exposed portion and the non-exposed portion. Subsequently, this toner image passes through the toner accumulation area in the developing area, and at this time, since the reverse voltage 17 is applied to the sleeve 13a, the excess toner in the non-exposed area is collected by the developing machine 13 by electrostatic force. To be done. At this time, the toner in the exposed portion is also slightly recovered, but most of the toner remains on the photosensitive belt 11 due to the electrostatic restraining force of the latent image charge and the toner charge, and the toner image 20 is formed.

In the image exposure unit, the photosensitive belt 11 is made of the transparent plate 30.
Since the toner is conveyed while in contact with the toner, the positional deviation of the photosensitive belt was ± 0.1 mm or less even when the toner contacted the toner.

The toner image 20 is electrostatically transferred onto the recording paper 21 using the transfer roller 22. The transferred toner image 24 is fixed on the recording paper by the thermal fixing device 25, and a semi-permanent recorded image 26 is obtained.

On the other hand, the residual toner 27 that has not been transferred is neutralized by the neutralization light source 28, loses the electrostatic restraint force, is recovered by the magnetic force of the developing device 13, and is reused. The next image formation is performed at the same time when the toner is collected. As described above, the simultaneous operation of collecting the residual toner and forming the image does not cause any trouble because the image exposing means 19 is on the opposite side of the developing machine 13.

(B) Description of another embodiment FIG. 5 is an illustration of another example of the LED optical system, and FIG.
The same parts as those in FIG. 4 are denoted by the same reference numerals, and the description thereof will be omitted. Reference numeral 31 is a tubular member having a guide surface 31a for guiding the photoconductor belt 11 to pass a predetermined course, and A part of the surface 31a is composed of a transparent member 321b through which light from the LED array 19a can pass, and the LED array 19a is further formed on the inner peripheral surface.
Is fixed.

Further, although not shown, a fan is provided on at least one side of the openings at both ends of the tubular member 31, and the tubular member 31
Is configured to blow air to the inner peripheral side of the.

By configuring as described above, the cooling air does not diffuse inside the photoconductor belt 11, the LED array 19a can be efficiently cooled, the photoconductor belt 11 does not vibrate, and the image No deterioration occurs.

Furthermore, if a filter is provided at the opening of the tubular member 31, scattered toner and dust will not enter.

(C) Description of Another Embodiment FIG. 6 is a schematic configuration diagram for explaining another embodiment of the image forming apparatus according to the present invention.

In the figure, the same parts as those in FIG. 2 are denoted by the same reference numerals and the description thereof will be omitted. In addition, 32 is a transparent hollow roller, a cylindrical member, made of transparent synthetic resin such as acrylic or glass. Further, it is provided so as to rotate in the same direction as the conveying direction of the photosensitive belt 11, and the supporting roller 12 on the recording unit side shown in FIG. 2 is omitted.

Inside the transparent hollow roller 32, an LED is provided as an image exposure means.
LED consisting of array 19a and selfoc lens array 19b
An array optical system 19 is installed. As shown in FIG. 7, the LED array optical system 19 is fixed to the main body of the device via a supporting member 35. The position of the LED array optical system 19 is set so that an image is formed on the surface of the transparent hollow roller 32.
The transparent hollow roller 32 is supported by a bearing 36 and can rotate without contact with the support member 35. A cooling fan 33 and a filter 34 are attached to one side surface (left side in the figure) of the support member 35. The support member 35 has a cylindrical structure as shown in FIG. 8, and has a hollow portion that supports the LED array optical system 19 at the central portion 35a and allows the cooling air from the cooling fan 33 to pass therethrough. It has a 35b. Although the cooling fan 33 is attached in this embodiment, both ends of the transparent hollow roller 32 may be closed by the filters 34 without attaching. Further, a seal member may be inserted between the transparent hollow roller 32 and the support member 35.

With the configuration described above, in addition to the effect obtained by the above-described embodiment, the number of supporting rollers 12 can be reduced, and the structure can be simplified and downsized.

〔The invention's effect〕

As described above, according to the present invention, since the transparent plate serving as the conveyance guide of the photoconductor belt is provided between the exposure unit and the development unit, it is easy to set the positions of the exposure unit and the development unit, and even after the setting, the exposure is performed. Since the body position does not shift, a clear image can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the principle of the present invention, FIG. 2 is a schematic configuration diagram showing an embodiment of the present invention, and FIG. 3 is a configuration diagram of a photoconductor belt,
FIG. 4 is a perspective view of the image exposure unit, FIG. 5 is an explanatory view of another example of the LED array optical system, FIG. 6 is an explanatory view of another embodiment, and FIG. 7 is another example of the LED optical system. FIG. 8, FIG. 8 is a configuration diagram of an end portion of the LED optical system, FIG. 9 is a schematic configuration diagram of a conventional example, and FIG. 10 is a diagram illustrating a conventional image forming process. In the figure, 1 is an endless belt type photoreceptor, 2 is a toner developing means,
2a is toner, 3 is image exposure means, 3a is an optical axis, 4 is a guide member, and 4a is a transparent member.

Claims (2)

[Claims] 1. A photoconductive layer (1c) of a photoconductor (1) comprising a transparent or semitransparent conductive layer (1b) and a photoconductive layer (1c) sequentially laminated on at least a transparent substrate (1a). A toner developing means (2) provided on the side, and an image exposing means (3) provided on the transparent substrate (1a) side of the photoconductor (1) facing the toner developing means (2). An image forming apparatus for forming a toner image by image-exposing the photoconductor (1), wherein the photoconductor (1) is formed into an endless belt, and the endless belt-like photoconductor (1) A guide member (4) which contacts the transparent substrate (1a) side and guides the endless belt-shaped photoreceptor (1) so as to pass through a predetermined path. It is provided at a position that intersects with
Further, the image forming apparatus is characterized in that the guide member (4) is composed of a transparent member (4a) at least at a portion intersecting with the optical axis (3a) of the image exposing means (3). 2. The guide member includes a tubular member and filter members provided at both ends of the tubular member, and the image exposing means is included in the tubular member. The image forming apparatus according to claim (1).