JPH0876641A - Image forming device - Google Patents

Abstract

PURPOSE: To immediately utilize a photoreceptor which is not excellent in temperature characteristics and moisture resistance by immediate heating and to immediately heat a photoreceptor base which is not excellent in heat conduction by using a heating means provided on the outside of an image forming body. CONSTITUTION: In the image forming device where a toner image is formed on the image forming body and transferred on a transfer material; the heating means 20 heating the image forming body 10 is allowed to abut on the image forming body 10 from the outside and set between a cleaning means 19 and an electrifying means 11. By heating the surface of the image forming body at the initial stage of preliminary rotation, the base substance 10a of the image forming body 10 is heated so that its temperature may rise to set temperature.

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, and in particular, a plurality of charging means, image exposing means and developing means are arranged on the peripheral surface of an image forming body to make one rotation of the image forming body. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic color image forming apparatus that superimposes toner images therein.

[0002]

2. Description of the Related Art Generally, in an electrophotographic image forming apparatus, a so-called in-drum heater is often used in which a heater is provided inside a photosensitive drum which is an image forming body in order to stabilize an image. On the other hand, as a method of forming a multicolor image, the number of photoreceptors of the same number as the required number of images,
An apparatus (A) that includes a charging device, a developing device, and the like, and forms a color image by superposing a single-color toner image formed on a photosensitive member on a transfer member or the like, or by rotating one photosensitive member a plurality of times for each color. A device for forming a color image by repeating charging, image exposure and development (B) or a device for forming a color image by sequentially performing charging, image exposure and development for each color within one rotation of one photoconductor (C). ) Etc. are known.

However, the above-mentioned device (A) has a drawback that the volume of the device becomes large because it requires the conveyance of a plurality of photoconductors or transfer bodies, while the device (B) has a disadvantage that the charging means, the image exposing means and the photoconductors. However, there is a restriction that the size of the formed image is limited to the surface area of the photoconductor or less, though the volume is reduced.

Further, although the apparatus (C) enables high-speed image formation, it is necessary to dispose a plurality of sets of a charging device, an image exposing means and a developing device within one circumference of the photosensitive member, and perform image exposure. The optical system may be contaminated with toner leaking from a developing device adjacent to the optical system, and the image quality may be impaired.To avoid this, it is necessary to increase the distance between the image exposure means and the developing device. There is a contradiction that the size of the device will increase.

For the purpose of avoiding the drawbacks of the above-mentioned obstacles in the apparatus (C), the substrate of the image forming body is made of a transparent material, and a plurality of image exposing means are housed therein to form an image. An apparatus has been proposed in which the photosensitive layer formed on the outer periphery of the substrate is exposed through the substrate (for example, JP-A-5-307307).

[0006]

As is well known, the image-forming body is hydrophilized by the ambient temperature and ozone generated by the charger during image formation, and is easily affected by humidity. In a color image forming apparatus using the above, the phenomenon remarkably causes image deterioration. Further, if the base of the photoconductor expands or contracts due to a change in temperature, the relative position with respect to the exposure means causes a change in the image formation position that cannot be optically ignored, and causes a problem in dot overlap in forming a superimposed color image. . Further, there is a limit to the use of the in-drum heater in the transparent photoconductor using glass or plastic having poor heat conductivity inside.

The present invention solves these problems and enables immediate heating of a photoreceptor having poor moisture resistance, particularly a photoreceptor such as a-Si or OPC, and immediate heating of a photoreceptor having poor thermal conductivity. An object of the present invention is to provide an image forming apparatus capable of recording a high quality image, particularly a color image forming apparatus.

[0008]

SUMMARY OF THE INVENTION Firstly, in the image forming apparatus for forming a toner image on an image forming body and then transferring the toner image onto a transfer material, a heating means for heating the image forming body is used. This is achieved by an image forming apparatus characterized in that it is brought into contact with the outside of the formed body and the installation position is set between the cleaning means and the charging means. Further, in the image forming apparatus, a plurality of sets of charging means, image exposing means, and developing means are arranged around the image forming body, and the image forming body is charged by the charging means, image exposing by the image exposing means, and In a preferred embodiment, the image forming apparatus is a color image forming apparatus that repeats development by the developing unit to form toner images on the image forming body in a superimposed manner and then collectively transfers the toner images to the transfer material. Also, a preferable embodiment is an image forming apparatus characterized in that the heating means is a roller-shaped heating means, and an image forming apparatus characterized in that the image forming body has a glass or plastic substrate. .

Secondly, in an image forming apparatus for transferring a toner image onto a transfer material after forming a toner image on the image forming body, heating means for heating the image forming body is brought into contact with the outside of the image forming body and preliminarily rotated. This is achieved by an image forming apparatus characterized in that the substrate of the image forming body is heated and raised to a set temperature by heating the surface of the image forming body at the beginning of the time.

In the image forming apparatus, a plurality of sets of charging means, image exposing means and developing means are arranged around the image forming body, and the image forming body is charged by the charging means and the image exposing means. An image forming apparatus is preferable, which is a color image forming apparatus that repeats image exposure and development by the developing unit to form toner images on the image forming body in a superimposed manner, and then collectively transfers the toner images to the transfer material. It is an embodiment, and the image forming apparatus characterized in that the heating means has a temperature detecting means of the image forming body is also a preferable embodiment.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming process of a color image forming apparatus according to an embodiment of the present invention and a structure of each mechanism will be described with reference to FIGS. FIG. 1 is a sectional configuration diagram showing an example of a color image forming apparatus suitable for carrying out the present invention.
FIG. 2 is an enlarged view of the main part near the heating means.

Reference numeral 10 is a photosensitive drum, which is a drum-shaped image forming body, and 11 (Y, M, C, K) is a scorotron charger, which is held at a predetermined potential with respect to the photosensitive layer of the photosensitive drum 10. A charging action is performed by the grid and corona discharge by the discharge wire, and a uniform potential is given to the photoconductor drum 10.

Reference numeral 12 (Y, M, C, K) is an F in which light emitting elements arranged in the axial direction of the photosensitive drum 10 are arranged in an array.
An exposure optical system composed of L, EL, PL, LED, LISA, PLZT, LCS in which elements having an optical shutter function are arranged in a line and a self-ox lens as an equal-magnification image forming element, and a separate image. The image signals of the respective colors read by the reading device are sequentially taken out from the memory and input as electrical signals to the exposure optical system 12 (Y, M, C, K).

Each of the exposure optical systems 12 (Y, M, C, K) is mounted on a cylindrical support member 30 and is housed inside the base of the photosensitive drum 10.

Reference numerals 13Y to 13K denote developing units for accommodating yellow (Y), magenta (M), cyan (C), and K (black) developers, respectively, which are used in the non-contact developing method, and each of which is a photosensitive drum 10. Developing sleeve 130 (Y, M, C, K) that rotates in the same direction while keeping a predetermined gap on the peripheral surface of the developing roller 130, and supply roller 131 that supplies developer to the developing sleeve 130 (Y, M, C, K). (Y, M, C, K), stirring roller 132 (Y, M, C)
M, C, K) and 133 (Y, M, C, K).

The developing device 13 (Y, M, C, K) is charged by the scorotron charger 11 (Y, M, C, K) described above, and the exposure optical system 12 (Y, M, C, K) is used. The electrostatic latent image formed on the photoconductor drum 10 by image exposure by means of imagewise reversal development in a non-contact state by application of a developing bias voltage.

The image of the original is read by an image reading apparatus separate from the present apparatus, and the image read by the image pickup device or the image edited by the computer is once used as an image signal for each color of Y, M, C and K. Stored and stored in memory.

When the image recording is started, the photosensitive drum driving motor (not shown) is started to rotate the photosensitive drum 10 in the clockwise direction. At the same time, a potential is applied to the photosensitive drum 10 by the charging action of the scorotron charger 11 (Y). Is started.

After the photosensitive drum 10 is applied with an electric potential,
In the exposure optical system 12 (Y), the exposure by the electric signal corresponding to the first color signal, that is, the yellow (Y) image signal is started, and the yellow (Y) of the original image is formed on the photosensitive layer on the surface by the rotational scanning of the drum. ) Form an electrostatic latent image corresponding to the image.

The latent image is reversely developed by the developing device 13 (Y) with the developer on the developing sleeve in a non-contact state, and a yellow (Y) toner image is formed in accordance with the rotation of the photosensitive drum 10.

Next, the photosensitive drum 10 is further provided with a scorotron charger 11 on the yellow (Y) toner image.
An electric potential is applied by the charging action of (M), and the exposure optical system 12
The exposure is performed by the electric signal corresponding to the second color signal of (M), that is, the image signal of magenta (M), and the developing device 13
By the non-contact reversal development by (M), a magenta (M) toner image is sequentially superposed and formed on the yellow (Y) toner image.

Scorotron charger by similar process
11 (C), the exposure optical system 12 (C), and the developing device 13 (C) further produce a cyan (C) toner image corresponding to the third color signal, and the scorotron charger 11 (K) and the exposure optical system. A black (K) toner image corresponding to the fourth color signal is sequentially formed by the 12 (K) and the developing device 13 (K), and the color image is formed on the peripheral surface of the photosensitive drum 10 within one rotation. Toner image is formed.

Each of these exposure optical systems 12 (Y, M, C, K)
The exposure of the organic photosensitive layer of the photoconductor drum 10 is performed through the transparent substrate described above from the inside of the drum. Therefore, the exposure of the image corresponding to the second, third, and fourth color signals is performed without any influence of the toner image previously formed, and is equivalent to the image corresponding to the first color signal. It is possible to form an electrostatic latent image. The support member 30 is used to stabilize the temperature inside the photoconductor drum 10 and prevent the temperature rise due to heat generation of the exposure optical system 12 (Y, M, C, K).
By using a material having good thermal conductivity, a heater is used at low temperature, and heat is radiated to the outside through a heat pipe at high temperature, it can be suppressed to a level without any trouble. Further, in the developing action by the developing device 13 (Y, M, C, K), the developing sleeve 130 is used.
A developing bias in which a direct current or an alternating current is applied to (Y, M, C, K) is applied, jumping development is performed by a one-component or two-component developer accommodated in the developing device, and the transparent conductive layer is grounded. A DC bias having the same polarity as the toner is applied to the photoconductor drum 10 to perform non-contact reversal development in which the toner is attached to the exposed portion.

The color toner image thus formed on the peripheral surface of the photosensitive drum 10 is sent out from the paper feeding cassette 15 by the sending roller 15a in the transfer device 14a, and is sent to the timing roller 16 by the carrying roller pair 15b and 15c. The photosensitive drum is conveyed and driven by the timing roller 16.
The image is transferred onto a transfer sheet P which is a transfer material that is fed in synchronization with the toner image on 10.

The transfer paper P on which the toner image has been transferred is removed from the charge by the static eliminator 14b and separated from the peripheral surface of the drum, and then is transferred to the fixing device 17 by the transfer belt 14e. In the fixing device 17, the fixing roller 17a and the pressure roller 17
After being heated and pressure-bonded between b to fuse and fix the toner on the transfer paper P, the toner is ejected from the fixing device 17 by the fixing exit roller pair 17d and is conveyed by the paper ejection conveyance roller pair 18a and is passed through the paper ejection roller pair 18. And is discharged onto a paper discharge tray 200 on the upper part of the apparatus.

On the other hand, the photosensitive drum 10 from which the transfer paper has been separated has the cleaning blade 19a in the cleaning device 19.
The surface of the photoconductor drum 10 is rubbed to remove and clean residual toner, and the toner image of the original image is continuously formed, or the toner image is temporarily stopped and a new toner image of the original image is formed. The waste toner scraped off by the cleaning blade 19a is discharged to a waste toner container (not shown) by the toner transport screw 19b.

The photosensitive drum 10, which is an image forming body, has a transparent conductive layer, a-Si, on the outer periphery of a cylindrical substrate 10a formed of a transparent member such as optical glass or transparent acrylic resin.
Layer or a photosensitive layer 10b such as an organic photosensitive layer (OPC). Reference numeral 20 denotes a roller-shaped heating unit that directly heats the surface of the photoconductor from the outside of the photoconductor layer 10b and quickly heats only the surface to remove moisture from the surface of the photoconductor. The first scorotron charger 11 ( Y) and the cleaning device 19 provided upstream of the photosensitive drum 10 in the rotation direction.
It is installed between the photoconductor layer 10 and the photoconductor layer 10 of the photoconductor drum 10 before the transfer residual toner is cleaned and image formation is started.
When there is no toner on the surface b, it contacts the photosensitive drum 10 and is driven to rotate. Reference numeral 40 is a heater temperature sensor provided in contact with the heating means 20, and 41 is a drum temperature sensor provided in contact with the non-image area at the end of the photosensitive drum 10. The heating means 20 is provided on the outer peripheral surface of the heating element 20a, which is a ceramic heater or an infrared heater, in order to make the temperature uniform.
It is covered with a high heat conductive layer 20b made of metal or the like and a rubber coating 20c for protecting the photoconductor, and is rotated by being brought into contact with the photoconductor drum 10. Therefore, at the time of heating, it is not affected by the transparent substrate 10a such as glass or resin which is poor in thermal conductivity and made of a thick substrate, and in particular, a plurality of scorotron chargers 11 (Y, M, C, K) are provided. The function of eliminating the adverse effect of moisture resistance on the photoconductor layer 10b due to the generation of a large amount of ozone due to the simultaneous use of.

Next, prior to the image formation, the heating means 20, the heater temperature sensor 40, and the drum temperature sensor 41 control the temperature of the photosensitive drum 10 for removing water on the drum surface, and the temperature control in a steady state. Will be described with reference to FIG. 3, which is an explanatory view of temperature control by the heating means.

Before the image formation, the photosensitive drum 10 is preliminarily rotated, and at the same time, the heating means 20 is set to the drum preliminary rotation waiting time t0.
Later, in the preheating application cycle t1, the off time is set to Δ
The surface of the photosensitive drum 10 is heated by turning on and off as t1. The surface temperature of the heater and the photosensitive drum at room temperature before rotation is T1, for example, 20 ° C, and the set temperature of the substrate of the photosensitive drum during image formation by heating is T2, for example, 40 ° C.
And The surface of the photosensitive drum during preheating is higher than the set temperature of the substrate,
A temperature higher by 10 to 40 ° C. is preferable, for example, heater temperature T3
Is turned on and off at 70 ° C. Due to the followability of thermal conductivity, the surface of the photoconductor drum warmed by the heater is turned on and off in the cycle t1 at a predetermined temperature T4 at the drum temperature sensor 1 which is lower than T3 at 50 to 60 ° C. The drum surface temperature tr1, tr2, ... Trn detected by the drum temperature sensor 41 at Δt1 when off
Rises gradually from room temperature as the substrate with poor thermal conductivity warms, and approaches the set temperature of the substrate. In this case, when 40 ° C is detected, that is, the substrate temperature is 40 ° C.
At this point, the pulse-shaped preheating cycle by the heating means 20 is completed, and the surface of the photoconductor drum is in a state where water is removed and image formation can be started. In the subsequent steady state, the voltage applied to the heater at the time of on is lowered to control the temperature of the image forming body. For example, the heat dissipation state is detected by the drum temperature sensor 41, and the steady heating cycle t2
Then, pulsed heating of, for example, 50 ° C. is performed so that the temperature during steady-state heating becomes T5, which is lower than T3, and on / off control is performed to keep the substrate at a constant temperature (40 ° C. in this case). Δt2 and Δt3 in the figure are obtained from the difference between the target drum temperature and the measured drum surface temperature T2.
It's time.

[0030]

According to the present invention, it is installed between the first scorotron charger for image formation and the cleaning device provided upstream in the rotational direction of the photosensitive drum,
Before the transfer residual toner is cleaned and image formation begins,
The surface of the photoconductor drum is heated by the heating means that comes into contact with the photoconductor drum when there is no toner on the surface of the photoconductor layer, and directly heats the photoconductor surface from outside the photoconductor layer to warm only the surface quickly. Removes water from the surface of the photoconductor, and therefore, when heated, is not affected by the transparent substrate such as glass or resin, which has poor thermal conductivity and is made of a thick substrate, and especially by using multiple scorotron chargers at the same time. , Acts to eliminate the adverse effect of moisture resistance on the photoreceptor layer due to the generation of a large amount of ozone. In particular, a-Si photoconductors and O
Enables immediate use by instantly heating the PC photoconductor. Further, by applying pulsed heating to the surface of the photoconductor drum at a predetermined temperature higher than the set temperature of the base during pre-rotation before image formation, the surface temperature is increased and the influence of the temperature characteristics and hydrophilicity of the photoconductor is affected. It is possible to provide an image forming apparatus, particularly a color image forming apparatus, which realizes stable operation of the photosensitive member and enables high-quality image recording by controlling so as to remove the image.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram showing an example of a color image forming apparatus suitable for carrying out the present invention.

FIG. 2 is an enlarged view of a main part near a heating unit.

FIG. 3 is an explanatory view of temperature control by heating means.

[Explanation of symbols]

 10 photoconductor drum 10a substrate 10b photoconductor layer 11 scorotron charger 12 exposure optical system 13 developing device 14a transfer device 14b static eliminator 15 paper feed cassette 16 timing roller 17 fixing device 18 paper ejection roller pair 19 cleaning device 20 heating means 20a heat generation Body 20b Heat conduction layer 20c Rubber coating 30 Support member 40 Heater temperature sensor 41 Drum temperature sensor P Transfer paper

Claims (7)

[Claims] 1. In an image forming apparatus for transferring a toner image onto a transfer material after forming a toner image on the image forming body, heating means for heating the image forming body is brought into contact with the outside of the image forming body, and an installation position is set. An image forming apparatus characterized by being set between a cleaning unit and a charging unit. 2. The image forming apparatus has a plurality of sets of charging means, image exposing means, and developing means arranged around the image forming body,
The toner image is superposed on the image forming body by repeating charging of the image forming body by the charging means, image exposure by the image exposing means and development by the developing means, and then batch transfer to the transfer material. The image forming apparatus according to claim 1, wherein the image forming apparatus is a color image forming apparatus for performing. 3. The image forming apparatus according to claim 1, wherein the heating unit is a roller-shaped heating unit. 4. The image forming apparatus according to claim 1, wherein the image forming body has a glass or plastic substrate. 5. In an image forming apparatus for transferring a toner image onto a transfer material after forming a toner image on the image forming body, a heating means for heating the image forming body is brought into contact with the outside of the image forming body and at the time of preliminary rotation. An image forming apparatus, wherein the substrate of the image forming body is heated and raised to a set temperature by heating the surface of the image forming body in the initial stage. 6. The image forming apparatus has a plurality of sets of charging means, image exposing means, and developing means arranged around the image forming body,
The toner image is superposed on the image forming body by repeating charging of the image forming body by the charging means, image exposure by the image exposing means and development by the developing means, and then batch transfer to the transfer material. The image forming apparatus according to claim 5, wherein the image forming apparatus is a color image forming apparatus. 7. The image forming apparatus according to claim 5, wherein the heating unit has a temperature detection unit for the image forming body.