JP2897066B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to an image forming apparatus which forms a toner image on a photoreceptor by simultaneously performing image exposure from the rear surface of the photoreceptor and developing the image. For the purpose of preventing, a photoconductor formed by laminating a transparent or translucent conductive layer and a photoconductive layer on a transparent substrate is sandwiched, an image exposure means is provided on the base side, and the photoconductive layer is provided on the photoconductive layer side. A recording sleeve facing the photoconductive layer has a fixed sleeve provided on the surface, and magnetic brush developing machines filled with a developer are arranged facing each other, and an image is formed by simultaneously performing image exposure and development. In the image forming apparatus, the recording electrode has a wide shape extending from the upstream side in the developer movement direction to the downstream side in the developer movement direction with respect to the image exposure position.

[Industrial applications]

The present invention relates to an image forming apparatus that forms a toner image on a photoreceptor by performing image development and image development from the back surface of the photoreceptor.

Current copiers or high-speed, high-print-quality printers generally use an electrophotographic recording system. This method is a so-called Carlson process in which a photosensitive member is used as a recording medium and recording is performed in steps of uniform charging, image exposure, development, transfer, fixing, charge removal, and cleaning.

In the Carlson process, a corona discharger is used for uniform charging, transfer, and static elimination. Since the corona discharger is configured to apply a high voltage of several kv to the corona wire, it has a disadvantage that it requires a high-voltage power supply and is susceptible to humidity, dust and the like, and thus has low reliability. Also, ozone is generated in the corona discharger, and the ozone generates an odor and has recently become a problem of harm to the human body.

Further, the Carlson process requires the above seven steps, and thus has a drawback that the apparatus becomes complicated and large.

In recent years, in view of the above problems, an image forming method which does not require a corona discharger and can be downsized is proposed. Specifically, a method in which a toner developing machine and an image exposing unit are arranged opposite to each other with a photoreceptor interposed therebetween to simultaneously perform image exposing and developing.

[Conventional technology]

FIG. 7 is a side view showing the structure of a main part of a conventional image forming apparatus of this type, in which 1 is a photoconductor, 2 is a magnetic brush developing machine, and 3 is an image exposure means.

The photoconductor 1 has a transparent conductive layer 1b, a photoconductive layer 1
The transparent conductive layer 1b is connected to the ground.

The magnetic brush developing machine 2 includes a magnet roller 2a that rotates counterclockwise as indicated by an arrow and a fixed sleeve 2b, and is disposed on the photoconductor layer 1c side of the photoconductor 1. On the surface of the sleeve 2b, a band-shaped recording electrode 5 insulated from the sleeve 2b by the insulating film 4 is provided. A voltage having a polarity opposite to the carrier polarity (positive polarity in the figure) of the photoconductive layer 1c is applied to the recording electrode 5 by a power supply 6, and a voltage having a polarity opposite to that of the recording electrode 5 is applied to the sleeve 2b. . The developer 2 is filled with a developer 8 in which a conductive carrier and an insulating toner are mixed, and the developer 8 is fixed in a clockwise direction indicated by an arrow when the magnet roller 2a rotates counterclockwise. It is transported on 2b.

The image exposure means 3 is disposed on the transparent substrate 1a side of the photoreceptor 1 so as to face the magnetic brush developing machine 2, and the optical axis of the exposure light crosses the recording electrode 5. LED is used as the image exposure means 3
An array optical system, laser optical system, EL optical system, liquid crystal shutter optical system, etc. can be used.

 Image formation by this apparatus is performed as follows.

In the device A having the above configuration, when the photoconductive layer 1c is image-exposed, photocarriers are generated in the photoconductive layer 1c. Applied voltage of recording electrode 5 (-100 to -600 V) among photocarriers
Carriers of the opposite polarity move to the surface of the photoconductive layer 1c and become latent image charges 9. As described above, in the portion A of the exposed portion, since the capacitance of the photoconductive layer 1c apparently increases, the amount of the adhered toner increases, and the exposed portion and the non-exposed portion form a toner image having a certain level of contrast. Next, in the portion B, a reverse voltage (0 to +100 V) is applied to the sleeve 2b and the developer reservoir 10 is provided, so that the excess toner in the non-exposed portion is collected by the developing device 2 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 1 due to the electrostatic binding force of the latent image charge 9 and the toner charge.
A clear toner image 11 is formed.

[Problems to be solved by the invention]

In the conventional apparatus having the above-described configuration, the recording electrode 5 on the sleeve 2b of the magnetic brush developing machine 2 is a metal piece having a width of 1 to 5 mm and generally having a width of 2 to 3 mm, and the central portion thereof is subjected to image exposure. It has become. Further, the length of the recording electrode 5 corresponds to the width of the developing device 2. Generally, the width dimension of the developing machine is
Determined by the width of the paper used for recording, so at least 200 to 300
mm. Therefore, the recording electrode 5 has a width of 1 to 5 mm and a length of 2 mm.
It becomes an elongated thing of 00-300mm. Further, the recording electrode 5
Is several tens of μm to be stuck on the sleeve 2b of the developing machine 2.
m and a thin metal foil.

Such a thin and thin metal piece is very difficult to handle. Therefore, as shown in FIG. It required skill to stick with high accuracy. Then, when an image is formed with the recording electrode 5 twisted as shown in FIG. 8, printing unevenness occurs in the toner image on the photosensitive member. As described above, since the conventional image forming apparatus uses the elongated recording electrodes, the productivity is poor and the print quality is deteriorated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus capable of preventing a decrease in print quality due to a mounting accuracy of a recording electrode.

[Means for solving the problem]

FIG. 1 is a diagram for explaining the principle of the present invention, in which 21 is a recording electrode. Note that the same reference numerals are used for constituent members that are common to those in the related art.

The photoreceptor 1 is configured by laminating a transparent conductive layer 1b and a photoconductive layer 1c on a transparent substrate 1a.

The magnetic brush developing machine 2 has a fixed sleeve 2b and is arranged on the photoconductive layer 1c side of the photoconductor 1. The developer 2 is filled with the developer 8.

The image exposure unit 3 is disposed on the side of the transparent substrate 1 a of the photoconductor 1 so as to face the developing device 2.

The recording electrode 21 has a wide shape extending downstream in the developer movement direction (clockwise direction in FIG. 1) with respect to the image exposure position A,
It is provided on the sleeve 2b. In this figure, the recording electrode 21
Are arranged on the sleeve 2b with the insulating film 22 interposed therebetween.

[Action]

Image formation on the photoconductive layer 1c of the photoconductor 1 is performed by simultaneously performing image exposure by the image exposure unit 3 and development by the developing unit 2. In this case, the recording electrode width is a parameter that greatly affects the print quality. The following experiment was performed to confirm this.

The setting of the recording electrode width is as shown in FIG. 2, and FIG. 2 (a) is extended in the developer moving direction based on the exposure position of image exposure.
For the electrode width L ₁ was a case of the electrode width L ₂ for printing experiments with second diagram the developer moving direction extended in the opposite direction (b) (in the present invention). The experimental results are as shown in FIG. 3, ○ marks indicate the development density in the case of L ₁ of FIG. 2 (a). In this case, the print density is large and stable, the fog density is about 0, and the electrode width does not affect the development density.
Also, △ marks indicate the development density in the case of L ₂ of FIG. 2 (b). In this case, when L ₂ = 2 mm or more, the fog density sharply increases. This is because the recording electrode extends to the pool (section B) of the developer, so that the background toner cannot be collected.

As described above, when the recording electrode width is extended in the developer moving direction, the developing density is not affected. Therefore, the width is 5mm
The recording electrode 21 which has been widened as described above can be used. The wide recording electrode 21 is easy to handle, unlike the conventional elongated recording electrode, and therefore can be accurately mounted on the sleeve 2b. As a result, there is no decrease in print quality due to the mounting accuracy of the recording electrodes.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 4 to 6.

FIG. 4 is a schematic diagram illustrating the structure of the image forming apparatus according to the present embodiment. In FIG. The same members as those in FIG. 1 are denoted by the same reference numerals.

As shown in FIG. 5, the photoconductor 31 is provided with a transparent conductive layer 31b of an ITO (indium oxide) deposited film on a transparent substrate 31a of polyethylene terephthalate having a thickness of 100 μm. A function-separated organic photoconductive layer having a thickness of about 13 μm and comprising a generating layer 31c and a CTL (charge transporting layer) 31d is provided. A phthalocyanine-based material was used for CGL, and a hydrazone-based material was used for CTL. The transparent conductive layer 31b of the photoreceptor 31 is connected to the ground, and the photoreceptor 31 itself is transported by a power system (not shown) connected to the film drive roller 32 in the direction indicated by the arrow in the figure.

The configuration of the developing machine 2 is as described above with reference to FIG.
Its main structure is as shown in a perspective view in FIG. In FIG. 6, reference numeral 32 denotes an image exposure position, and reference numeral 33 denotes a developer pool position. The insulating film 22 is formed of polyimide, on which a strip-shaped recording electrode 21 made of copper foil is adhered. The width of the recording electrode 21 is set to 10 mm, which is easy to handle. The width is not limited to 10 mm as described above with reference to FIG. When such a wide recording electrode 21 is used, the recording electrode 21 can be stuck straight.
As shown in the figure, it can be the end of the recording electrode 21.
The developer pooling position 33 is located upstream in the developer moving direction.

A hole transfer type was used for the photoconductive layers 31c and 31d in this example. Therefore, a negative voltage is applied to the recording electrode 21 by the power supply 6. This voltage is suitably -100 to -600V. The power supply 7 applies a positive voltage to the sleeve 2b. This voltage is suitably from 0 to + 100V.

The image exposure unit 3 is disposed at a position facing the magnetic brush developing machine 2 with the photoconductor 31 interposed therebetween. The image exposure means 3 includes an LED array 3a that emits light according to an image signal,
Selfoc lens array for collecting the image light of array 3a
3b and a glass plate 3c for positioning the photoconductor 31 so that the focal position of the image light does not shift.

Numeral 34 denotes a toner image formed on the photoconductor 31, and numeral 35 denotes a recording paper. Reference numeral 36 denotes a transfer rubber roller.
200 to +600 V). Numeral 38 denotes a toner image electrostatically transferred to the recording paper 35, which is fixed on the recording paper 35 by a heat roller fixing device 39 to become a semi-permanent recording image 40.

Reference numeral 41 denotes a residual toner image remaining on the photoconductor 31 after transfer. 42 is the charge of the residual toner image 41 and the photoconductive layers 31c and 31d.
This is a static elimination light source for removing the latent image charges in the inside. Reference numeral 43 denotes a toner image that has lost electrostatic restraining force due to charge elimination.

 Next, an image recording procedure will be described.

The photosensitive member 31 was moved in the direction of the arrow, the magnet roller 2a of the developing machine 2 was rotated, the developer 8 was conveyed in the direction of the arrow, the developer reservoir 10 was formed, and a voltage was applied to the recording electrode 21 and the sleeve 2b, respectively. In this state, the photoreceptor 31 is image-exposed by the image exposing means 3. As a result, photocarriers are generated in the CGL 31C, and the holes therein move to the vicinity of the surface of the photoreceptor in the CTL 31d to become latent image charges. Hereinafter, a toner image 34 is formed on the surface of the photoconductor 31 according to the principle described in the section of the related art.

Next, the toner image 34 is electrostatically transferred to the recording paper 35 by using a transfer rubber roller 36. The transferred toner image 38 is fixed on the recording paper 35 by the fixing device 39, and a semi-permanent recording image 40 is obtained.

On the other hand, the residual toner image 41 remaining on the photoconductor 31 after the transfer is
The charge is removed using the charge removing light source 42. Static electricity removed toner image 43
Are the magnetic force of the developing machine 2, the scraping of the developer 8, and the sleeve.
It is collected and reused by the electrostatic force generated by the applied voltage of 2b. The next image formation is performed simultaneously with the collection of the residual toner image 43. Simultaneous recovery of the residual toner image 43 and formation of the next image in this manner cause no problem since the image exposure unit 3 and the developing machine 2 are located opposite to each other with the photoconductor 31 interposed therebetween.

According to the present example, the attachment of the recording electrodes was facilitated, and a decrease in print quality due to the attachment accuracy of the recording electrodes could be prevented.

The photoreceptor material can be used as an organic material such as a phthalocyanine-based material, PVK-TNF, an azo-based dye, a thiapyrylium dye, and an inorganic material such as a selenium-based photoreceptor, a-Si, Cds, or zinc oxide. What is necessary is just what shows the said characteristic.

Further, as the image recording process, in the above description, an example was described in which the residual toner remaining on the photoreceptor after transfer was collected by a magnetic brush developing machine. However, a process of removing the residual toner with a brush cleaner or a blade cleaner may be used. ,
In the transfer step, the example using the roller transfer method has been described above, but the same effect can be obtained by using the corona transfer method.

Further, the present invention is not limited to an image forming apparatus such as a printer as in the present embodiment, but can be applied to a display device for directly viewing a toner image on a photoreceptor without providing a transfer process, and can obtain a sufficient effect. it can.

〔The invention's effect〕

As described above, according to the present invention, since the recording electrode has a wide shape extending downstream in the developer movement direction, the recording electrode can be mounted on the sleeve of the developing machine with high accuracy, and the recording electrode mounting accuracy is reduced. This makes it possible to prevent the print quality from deteriorating.

[Brief description of the drawings]

FIG. 1 is a view for explaining the principle of the present invention, FIGS. 2 (a) and 2 (b) are views for explaining the procedure for setting the width of the recording electrode in FIG. 1, FIG. 3 is a view for explaining the effect of the present invention, and FIG. FIG. 5 is a cross-sectional view showing the structure of a photoreceptor, FIG. 6 is a perspective view showing the main structure of a developing device, FIG. FIG. 8 is a side view showing the structure of a main part of a conventional image forming apparatus. FIG. 8 is a perspective view showing a conventional recording electrode attached state. In the figure, 1 is a photoconductor, 1a is a transparent substrate, and 1b is a transparent conductive layer. , 1c is a photoconductive layer, 2 is a magnetic brush developing machine, 2b is a fixed sleeve, 3 is an image exposure means, 8 is a developer, and 21 is a recording electrode.

Claims (1)

(57) [Claims] 1. A photoconductor (1) comprising a transparent or translucent conductive layer (1b) and a photoconductive layer (1c) laminated on a transparent substrate (1a). Image exposure means (3)
On the photoconductive layer (1c) side, a fixed sleeve (2b) having a recording electrode (21) provided on the surface facing the photoconductive layer (1c), and filled with a developer (8) An image forming apparatus in which the magnetic brush developing machines (2) are arranged to face each other, and image exposure and development are performed at the same time to form an image, wherein the recording electrode (21) moves developer with reference to the image exposure apparatus. An image forming apparatus having a wide shape extending from the upstream side to the downstream side in the developer movement direction.