JPH04280271A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the travel of latent image electric charge, and enable high development density and clear image to be obtained by using a photo-sensitive body having an electric charge generation layer and an electric charge transport layer laminated to the inverse order of conventional lamination. CONSTITUTION:A photo-sensitive body 19 has an electric charge generation layer 19d and an electric charge transport layer 19c laminated to the inverse order of conventional lamination. When light 11 is irradiated to the aforesaid photo-sensitive body 19 for image exposure, an electron hole pair is generated in the electric charge generation layer 19d. Negative recording voltage 9a is applied to the second development means 8A and, therefore, toner is collected from a non-exposure section due to the addition of weak electric field. In this case, negatively charged electrons or latent image electric charge 6a residual in the electric charge generation layer 19d cannot travel, due to a blocking layer formed with the interface of the electric charge generation layer 19d and the electric charge transport layer 19c. As a result, the static restraint of the latent image electric charge 6a and toner electric charge can be strongly retained. Consequently, toner deposited on the section of the latent image electric charge 6a becomes hard to be collected by the second development means 8A, thereby enabling development density to be maintained at a high level.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus that performs image exposure from one side of a photoreceptor and simultaneously develops the other side to form a toner image on the photoreceptor.

Image forming apparatuses using an electrophotographic recording method are commonly used as copying machines or printers with high speed and high print quality.

[0003] The electrophotographic recording method uses a photoreceptor as a recording medium and performs recording through the steps of uniform charging, image exposure, development, transfer, fixing, static elimination, and cleaning, and is a so-called Carlson process. be.

By the way, in the Carlson process, a corona discharger is used for uniform charging, transfer, and static elimination.

However, since the corona discharger is configured to apply a high voltage of several kilovolts to the corona wire, it requires a high-voltage power source and is easily affected by humidity, dust, etc.
It has the disadvantage of low reliability.

[0006] In addition, ozone generated in a corona discharger generates an odor, and the harmfulness of ozone to the human body has become a problem.

On the other hand, in the Carlson process, the above-mentioned seven steps are necessary for image formation, which has the disadvantage that the image forming apparatus becomes complicated and large.

On the other hand, in consideration of these problems, image forming methods and image forming apparatuses have been proposed that focus on miniaturization of the apparatus without using a corona discharger.

Specifically, the present invention is an image forming method and an image forming apparatus in which a toner developing device and an image exposing means are disposed opposite to each other with a photoreceptor in between, and image exposure and development are performed simultaneously. The present invention relates to an image forming apparatus, and is an invention made to improve image density.

0010

[Prior Art] Image forming apparatuses that simultaneously perform image exposure and development by arranging a toner developing device and an image exposing means opposite to each other with a photoreceptor in between are available in two types: a device with two stages of developing machines and a device with only one stage. There is. However, the principle of both image forming apparatuses is the same. Here, both devices will be explained separately.

(1) Image forming device with two stages of developing machines FIG. 6 is a model diagram explaining the image forming device and its principle (1). (a) is a diagram showing the configuration, (b) (c) ) is a diagram explaining the principle. In this figure, the developing device has a roller-like shape, and this figure is a view seen from the axial direction.

1) Structure The photoreceptor 1 is composed of a transparent substrate 1a, a transparent conductive layer 1b, and a photoconductive layer 1c, and the transparent conductive layer 1b is connected to ground.

On the other hand, the first magnetic brush developing device 2 provided on the photoconductive layer 1c side of the photoreceptor 1 consists of a magnet roller 2a and a sleeve 2b, and both the magnet roller 2a and the sleeve 2b are configured to be freely rotatable. are doing.

The first magnetic brush developing device 2 also has a polarity (positive polarity in the figure) of the charges moving in the photoconductive layer 1c.
A voltage 3 of opposite polarity is applied. Here, this voltage will be referred to as the first recording voltage 3.

The first magnetic brush developing device 2 is filled with a one-component or two-component developer 4, and the developer 4 is conveyed by rotation of the magnet roller 2a and sleeve 2b.

On the other hand, on the transparent substrate 1a side of the photoreceptor 1,
An image exposure means 5 is provided at a position facing the first magnetic brush developing device 2. Incidentally, as the image exposure means 5, an LED array optical system, a laser optical system, an EL optical system, a liquid crystal shutter optical system, etc. can be used.

Next, a second magnetic brush developing device 8 is provided downstream of the first magnetic brush developing device 2 in the direction in which the photoreceptor 1 moves. This second magnetic brush developing machine 8 is composed of a magnet roller 8a and a sleeve 8b, similar to the first magnetic brush developing machine 2.
b are configured to be rotatable.

Further, a voltage 9 having a polarity opposite to that of the recording voltage 3 of the first magnetic brush developing device 2 is applied to the second magnetic brush developing device 8 . Here, this voltage is changed to the second recording voltage 9
I will call it.

The second magnetic brush developing device 8 is filled with one-component or two-component developer 4, and the developer 4 is conveyed by rotation of the magnet roller 8a and sleeve 8b.

Although the magnetic brush developing machines 2 and 8 using a magnetic developer are exemplified as the developing machine described above, a developing machine using a non-magnetic developer may also be used.

2) Image formation principle ■ Image exposure and first development When image exposure is performed by irradiating the photoreceptor 1 with light 11 from the image exposure means 5, electrons and holes are created in the photoconductive layer 1c of the photoreceptor 1. A pair occurs.

On the other hand, since a negative first recording voltage 3 is applied to the first magnetic brush developing device 2, positively charged holes of the electron-hole pairs are transferred to the photoconductive layer of the photoreceptor 1. It moves near the surface of 1c and forms a latent image charge 6.

Therefore, in the exposed portion of the photoreceptor 1, the capacitance of the photoconductive layer 1c increases apparently, and the amount of adhered toner increases. Note that toner also adheres to non-exposed areas of the photoreceptor 1.

That is, a toner image 7 having a certain degree of contrast is formed between the exposed area and the non-exposed area. Here, this step will be referred to as first development.

(2) Second Development Next, the photoreceptor 1 that has completed the first development moves upward in the figure, that is, to the second magnetic brush developing machine 8.

By the way, a recording voltage 9 having a polarity opposite to that of the first recording voltage 3 is applied to the sleeve 8b of the second magnetic brush developing device 8.

Therefore, of the toner deposited in the first magnetic brush developing device 2, excess toner in non-exposed areas can be collected by electrostatic force.

At this time, a small amount of toner in the exposed area is also collected, but most of the toner remains on the photoreceptor 1 due to the electrostatic binding force of the latent image charge 6 and the toner charge, and a toner image 10 can be formed. Here, this step will be referred to as second development.

(2) Image forming device with one stage of developing machine FIG. 7 is a model diagram explaining the image forming device and its principle (2), (a) is a diagram showing the configuration, (b) (c) is a diagram explaining the principle. In this figure, the developing device has a roller-like shape, and this figure is a view seen from the axial direction.

1) Structure The structure of the photoreceptor 1 and the structure of the exposure means 5 are as described in (1) above.
It is similar to Then, a developing machine 12 is placed across the photoreceptor 1.
is arranged at a position opposite to the exposure means 5.

The developing device 12 provided on the photoconductive layer 1c side of the photoreceptor 1 includes a magnet roller 12a and a sleeve 12b.
The magnet roller 12a is configured to be rotatable.

Furthermore, a strip-shaped recording electrode 14 is provided on the surface of the sleeve 12b and is insulated from the sleeve 12b with an insulating film 13.

The recording electrode 14 has a polarity (positive polarity in the figure) of the charge moving in the photoconductive layer 1c of the photoreceptor 1.
A voltage 16 of opposite polarity is applied. That is, the first recording voltage 16.

On the other hand, the recording electrode 14 is attached to the sleeve 12b.
A voltage 17 of opposite polarity is applied. That is, the second recording voltage 17.

Further, the developing device 12 is filled with a developer containing a mixture of a conductive carrier and an insulating toner, or a conductive magnetic toner 4, and is conveyed in the direction of the arrow in the figure.

2) Image formation principle ■Image exposure and first development Opposed portion of recording electrode 14 and photoreceptor 1, ie, FIG. 7(a)
In part A of , light 11 is transmitted from the image exposure means 5 to the photoreceptor 1.
When image exposure is performed by irradiating with
An electron-hole pair is generated within c.

On the other hand, since the negative first recording voltage 16 (-100 to -600 V) is applied to the recording electrode 14, positively charged holes of the electron-hole pairs are transferred to the photoreceptor 1. It moves to the vicinity of the surface of the photoconductive layer 1c and forms a latent image charge 6.

Therefore, in the exposed portion of the photoreceptor 1, the capacitance of the photoconductive layer 1c increases apparently, and the amount of adhered toner increases. Note that toner also adheres to non-exposed areas of the photoreceptor 1.

That is, a toner image 7 having a certain degree of contrast is formed between the exposed area and the non-exposed area, and the first
Development is complete.

■The downstream side of the second development recording electrode 14 in the moving direction of the photoreceptor 1, that is, FIG.
In part B of (b), since the direction in which the developer 4 is conveyed and the direction in which the photoreceptor 1 moves are opposite, the developer 4 accumulates in a portion 18 .

By the way, the sleeve 12b has a recording voltage 17 (0 to +100
V) is being applied.

Therefore, of the toner adhered in the A section, excess toner in the non-exposed area can be collected in the B section by electrostatic force.

At this time, a small amount of the toner in the exposed area is also collected, but most of the toner remains on the photoreceptor 1 due to the electrostatic binding force of the latent image charge 6 and the toner charge, and a toner image 10 can be formed. That is, the second development is completed.

[0044]

[Problem to be solved by the invention] However, the above (1)
and (2) in the second developing step of the image forming apparatus,
Too much toner attached to the latent image charge 6 may be collected in the first development step, resulting in a decrease in development density (image density). Next, the details will be explained.

(1) In the case of an image forming apparatus equipped with two stages of developing machines (see FIGS. 6(b) and 6(c)).
The recording process is shown assuming that

The functionally separated photoreceptor 1 consists of at least a transparent substrate 1a, a transparent conductive layer 1b, a charge generation layer 1d that generates electron-hole pairs upon image exposure, and a charge generation layer 1d that transports the charges generated in the charge generation layer 1d. It is constructed by sequentially laminating transport layers 1e. That is, it is a photoreceptor in which the photoconductive layer 1c is composed of a charge generation layer 1d and a charge transport layer 1e.

When such a photoreceptor 1 is used, the image shown in FIG. 6 (
As shown in b), the electron-hole pairs generated in the charge generation layer 1d upon image exposure are moved by the electric field formed by the recording voltage 3. That is, positively charged holes move toward the surface of the photoreceptor 1 through the charge transport layer 1e to form a latent image charge 6, and negatively charged electrons flow to the ground.

In this case, even if the polarity of the recording voltage 3 is reversed and a positive voltage is applied to the first developing device 2, electrons will not move to the charge transport layer.

That is, the charge transport layer 1e and the charge generation layer 1
Since the interface with d forms a block layer (barrier),
Positive charges can pass through this interface, but negative charges cannot.

Next, in the second developing device 8 which collects the toner in the non-exposed area, that is, the background area, a toner recovery electric field is applied to the charge transport layer 1e by the recording voltage 9, as shown in FIG. 6(c). .

Therefore, in some cases, the positive latent image charge 6 moves. That is, the latent image charge 6 on the surface of the photoreceptor 1 moves again to the conductive layer 1b side of the photoreceptor 1, weakening the adhesion force of toner on the surface of the photoreceptor 1.

As a result, the amount of toner adhering to the latent image on the photoreceptor 1 decreases, and the density of the image decreases.

(2) Image forming apparatus with one stage of developing machine (Fig. 7
(See (b) and (c)) In the case of this apparatus as well, the image density decreases for the same reason as in (1) above.

That is, as shown in FIG. 7(b), the positive latent image charges 6 in the area A formed by the image exposure and the recording voltage 16 applied to the recording electrode 14 are as shown in FIG. 7(c).
), the toner moves toward the conductive layer 1b in portion B and weakens the adhesion force of the toner on the surface of the photoreceptor 1.

As a result, the amount of toner adhering to the latent image on the photoreceptor 1 decreases, and the density of the image decreases.

(3) Problem The technical problem of the present invention is to solve the above-mentioned problems in the image forming apparatus, and to improve the developed density by making the latent image charge not move or hardly moving in the second development step. An object of the present invention is to realize an image forming apparatus that can obtain clear images with high image density.

[0057]

[Means for Solving the Problems] Figure 1 is a diagram explaining the basic principle (1) of the present invention, in which (a) shows the configuration of a developing device, and (b) shows the configuration of a photoreceptor. figure,
(c) and (d) are diagrams showing the operating principle.

FIG. 2 also shows the basic principle (2) of the present invention.
(a) is a diagram showing the configuration of the developing device, (b) is a diagram showing the configuration of the photoconductor, and (c) (d) is a diagram explaining the configuration of the photoreceptor.
) is a diagram showing the operating principle.

The present invention is characterized in that the charge generation layer 19d and the charge transport layer 19c are stacked in the reverse order from the conventional stacking order.

(1) Image forming apparatus with two stages of developing machines (see FIG. 1) It is assumed that the image forming apparatus has the following structural requirements (1) to (2).

■Photoreceptor 1 formed by laminating a transparent substrate 1a, a transparent or translucent conductive layer 1b, and a photoconductive layer 1c.

0
■First developing means 2A disposed on the photoconductive layer 1c side of the photoreceptor 1 and filled with developer 4

■First voltage applying means 3a for applying voltage to the first developing means 2A

(2) Image exposure means 5 provided on the transparent substrate 1a side of the photoreceptor 1 and at a position opposite to the first developing means 2A, which performs image exposure based on image data.

(2) A second developing means 8A disposed on the downstream side of the first developing means 2A in the direction of movement of the photoreceptor 1.

006
6] ■ A second voltage applying means 9a that applies a voltage of opposite polarity to the first voltage applying means 3 to the second developing means 8A.

In the image forming apparatus having the configurations (1) to (4) above, the photoreceptor 1 includes at least a transparent substrate 19a and a transparent or translucent conductive layer 19.
This is an image forming apparatus using a photoreceptor 19 in which a charge transport layer 19c and a charge generation layer 19d are sequentially laminated.

(2) Image forming apparatus with one stage of developing machine (see FIG. 2) An image forming apparatus having the following structural requirements (1) to (2) is assumed.

■Photoreceptor 1 formed by laminating a transparent substrate 1a, a transparent or semitransparent conductive layer 1b, and a photoconductive layer 1c.

0
■Magnetic brush developing device 12 placed on the photoconductive layer 1c side of the photoreceptor 1 and filled with developer 4

■Sleeve 12b of magnetic brush developing machine 12
A recording electrode 14 is provided above and insulated from the sleeve 12b.

■ A reservoir 1 of the developer 4 provided close to the recording electrode 14 and on the downstream side in the direction of movement of the photoreceptor 1
8

■First voltage application means 16a for applying voltage to the recording electrode 14

■Second voltage application means 17a that applies a voltage of opposite polarity to the sleeve 12b to the first voltage application means 16a.

(2) Image exposure means 5 provided on the transparent substrate 1a side of the photoreceptor 1 and at a position facing the recording electrode (14), and performs image exposure based on image data.

In the image forming apparatus having the configurations (1) to (4) above, the photoreceptor 1 includes at least a transparent substrate 19a and a transparent or translucent conductive layer 19.
This is an image forming apparatus using a photoreceptor 19 in which a charge transport layer 19c and a charge generation layer 19d are sequentially laminated.

(3) In the image recording apparatus in which a protective layer is provided on the photoreceptor, that is, in the image forming apparatus of (1) and (2) above, the surface protective layer that protects the charge generation layer 19d is replaced by the charge generation layer 19d. This is an image forming apparatus using a photoreceptor provided above.

[0078]

[Operation] Although solutions (1) and (2) are different in the configuration of the image forming apparatus on which they are based, their image forming principles are the same. Furthermore, the structure of the photoreceptor 19 used in the image forming apparatus is also the same.

(1) Image forming apparatus with two stages of developing machines (see FIGS. 1(c) and 1(d)) The photoreceptor 19 used in the image forming apparatus of the present invention is shown in FIG.
b) Compared to the conventional photoreceptor 1 shown in FIGS. 7(b) and 7(c), the charge generation layer 19d and the charge transport layer 19 are
The feature is that the stacking order of c is reversed.

The polarities of the voltage applying means 3a for applying a recording voltage to the first developing means 2A and the voltage applying means 9a for applying a recording voltage to the second developing means 8A are shown in FIGS. 6 and 7. This is the opposite of conventional image forming apparatuses.

As a result, the latent image charges 6a formed in the first development are not moved in the second development, and an image with high print density is obtained. The details will be explained next.

That is, in the first development, as shown in FIG. 1(c), when image exposure is performed by irradiating the light 11 from the image exposure means 5 onto the photoreceptor 19, the charge generation layer 19d of the photoreceptor 19 is exposed. Electron-hole pairs are generated within.

On the other hand, since a positive recording voltage 3a is applied to the first developing means 2A, positively charged holes of the electron-hole pairs are transferred to the charge transport layer by the strong electric field caused by the recording voltage 3a. 19c and flows into the transparent conductive layer 19b. Furthermore, the negatively charged electrons remain in the charge generation layer 21d and become latent image charges 6a.

Next, in the second development, as shown in FIG. 1(d), since a negative recording voltage 9a is applied to the second developing means 8A, a weak electric field due to the recording voltage 9a is applied. The toner in the non-exposed area, that is, the background area, is collected by

By the way, in the second development, the negatively charged electrons remaining in the charge generation layer 19d, that is, the latent image charges 6a, cannot pass through because the interface between the charge generation layer 19d and the charge transport layer 19c acts as a blocking layer. .

Therefore, since the electrostatic binding force between the latent image charge 6a and the toner charge can be strongly maintained, the latent image charge 6a
The toner adhering to the area becomes difficult to be collected by the second developing means, and the developed density can be maintained at a high level.

In other words, the important point in the present invention is that the interface between the charge generation layer 19d and the charge transport layer 19c is configured so that either positive or negative charges can pass therethrough, but the other charge cannot pass therethrough. The point is that there is.

Incidentally, in general, in organic photoreceptors, positive charges (holes) can pass through the interface, but negative charges (electrons) cannot. However, depending on the material selection of both organic and inorganic photoconductive materials, it is also possible to form a blocking layer or barrier that acts in the opposite manner.

(2) Image forming apparatus in case one stage of developing machine is provided (see FIGS. 2(c) and 2(d)) In the present invention, the operation is the same as in (1) above. That is, using the same photoreceptor 19 as in (1) above,
The recording voltage applied to the recording electrode 14 and the sleeve 12d, that is, the polarity of the first voltage application means 16a and the polarity of the second voltage application means 17a are also the same.

The effects in the first development shown in FIG. 2(c) and in the second development shown in FIG. 2(d) are also the same.

That is, the latent image charges 6a formed in the first development are not moved in the second development, and an image with high developed density can be obtained.

(3) Image recording device in which a protective layer is provided on the photoreceptor By providing a surface protective layer that protects the charge generating layer 19d, a toner image is formed on the surface protective layer. It becomes possible to prevent the deterioration of
The life of the photoreceptor 19 can be extended.

[0093]

[Embodiment] Next, how the image forming apparatus according to the present invention can be practically implemented will be explained with reference to an embodiment.

(1) Example-1 FIG. 3 is a diagram explaining Example-1, in which (a) is a model diagram of an image forming apparatus, (b) is a diagram showing the configuration of a photoreceptor,
It is. Note that (a) is a view of the photosensitive drum viewed from the direction of its rotation axis.

1) Structure - Photosensitive drum The photosensitive drum 20 has a transparent conductive layer 20b made of ITO (indium tin oxide) vapor deposited on a transparent substrate 20a of glass, as shown in FIG. 3(b). consists of a charge transport layer 20c and a charge generation layer 20d. That is,
It is a functionally separated organic photoreceptor.

[0096] Then, the mechanically weak charge generation layer 20d
A surface protection layer 20e is laminated for the purpose of protecting the surface. Note that the thickness of the photoreceptor is approximately 20 μm.

Incidentally, a phthalocyanine material was used for the charge generation layer 20d, and a hydrazone material was used for the charge transport layer 20c. Furthermore, polyethylene terephthalate was used for the surface protective layer 20e.

In the image forming apparatus, the transparent conductive layer 20b of the photoreceptor drum 20 is connected to ground, and the photoreceptor drum 20 is rotated and transported in the direction of the arrow in the figure by a driving power system not shown. .

(1) First magnetic brush developing machine The first magnetic brush developing machine 2B consists of an internal magnet roller and an external sleeve, and the sleeve is configured to be freely rotatable.

A recording voltage having a polarity opposite to that of the latent image charges generated in the photoconductive layer, that is, the charge generation layer 20d and the charge transport layer 20c, that is, the first recording voltage 3b, is applied to the developing device 2B.

Incidentally, the photoconductive layers 31c, 3 of this example
A hole transfer type was used for 1d. Therefore, a positive recording voltage 3b is applied to the first magnetic brush developing device 2B. Note that the recording voltage 3b is +100 to +600.
V is appropriate.

[0102] Then, this first magnetic brush developing machine 2B
A developer 4 containing a mixture of a conductive carrier and an insulating toner
is filled and conveyed by rotation of the sleeve.

① Image Exposure Means Image exposure means 5a is disposed at a position facing the first magnetic brush developing device 2B with the photosensitive drum 20 in between.

Incidentally, the image exposure means 5a is composed of an LED array that emits light in accordance with an image signal and a SELFOC lens array that focuses the image light of the LED array.

Note that the toner image 7b on the photosensitive drum 20 is
Toner is also attached to the non-exposed area, that is, the background area.

(2) Second magnetic brush developing device The second magnetic brush developing device 8B is provided on the downstream side in the rotational direction of the photosensitive drum 20 when viewed from the first magnetic brush developing device 2B.

[0107] The second magnetic brush developing machine 8B is composed of a magnet roller and a sleeve, similar to the first magnetic brush developing machine 2B, and the sleeve is configured to be freely rotatable.

Then, a recording voltage of opposite polarity to the first recording voltage 3b, that is, a second recording voltage 9b, is applied to the second magnetic brush developing device 8B. By the way, the recording voltage 9
b is suitably between 0V and -100V.

[0109] Furthermore, the second magnetic brush developing machine 8B includes:
A developer 4 similar to the developer filled in the first magnetic brush developing device 2B is filled and conveyed by rotation of the sleeve.

■Transfer roller The transfer roller 22 is made of a conductive rubber roller.
A voltage of -200 to -600 V is applied from a power source 23 to the transfer roller 22.

The transfer roller 22 is in pressure contact with the photosensitive drum 20, and when the recording paper 21 is conveyed between the transfer roller 22 and the photosensitive drum 20, the toner image on the photosensitive drum 20 is transferred to the recording paper. Transfer to 21.

(2) Heat Fixing Machine The heat fixing machine 25 is a device that conveys the recording paper 21 between heated rollers and fixes the toner image 24 on the recording paper 21 to obtain a semi-permanent recorded image 26.

(2) Static Eliminating Light Source The static eliminating light source 28 is a device that uniformly exposes the photosensitive drum 20 to remove latent image charges in the charge transport layer 20c and the charge generating layer 20d of the photosensitive drum 20. Incidentally, at this time, the charge of the residual toner 27a adhering to the photosensitive drum 20 can also be removed at the same time.

2) Photoconductive material of photosensitive drum Photosensitive drum 2
Examples of photoconductive materials include organic materials such as phthalocyanine materials, PVK-TNF, azo dyes, and thiapyrylium dyes, as well as inorganic materials such as selenium photoreceptors, a-
Si, CdS, zinc oxide, etc. can be used.

[0115] Both the above-mentioned organic materials and inorganic materials can be used for both the charge generation layer 20d and the charge transport layer 20c. However, it is necessary to form an interface (barrier) through which only charges of one polarity can pass. Incidentally, in this example, it was formed so that only positive charges could pass through.

3) Operation (image formation and image recording procedure)
Form and record an image using the following steps ① to ②.

(2) Image exposure step The photosensitive drum 20 is rotated and conveyed in the direction of the arrow in the figure. On the other hand, the first and second magnetic brush developing machines 2B and 8B are rotated, and the respective developers 4 are conveyed in the direction of the arrow in the figure.

[0118] Then, the first and second recording voltages 3b,
9b is applied, the photosensitive drum 20 is subjected to image exposure by the image exposure means 5a.

■Development stage When image exposure is performed, the charge generation layer 20d of the photosensitive drum 20
In this case, electron-hole pairs are generated, and the electrons are transferred to the charge transport layer 20c.
The holes flow through the transparent conductive layer 20b, while the holes remain in the charge generation layer 20d, forming latent image charges.

Therefore, in the exposed area, the capacitance of the photoconductive layer, that is, the charge generation layer 20d and the charge transport layer 20c, increases apparently, and the amount of adhered toner increases compared to the non-exposed area. That is, a toner image 7b having a certain degree of contrast is formed between the exposed area and the non-exposed area (first development).

[0121] Then, the photosensitive drum 20 sequentially rotates,
Excess toner adhering to the non-exposed areas of the toner image 7b is collected by the electrostatic force of the second magnetic brush developing device 8B (second development).

In the photosensitive drum 20 of this embodiment, the electrostatic latent image on the photosensitive drum 20 is not weakened by the second magnetic brush developing device 8B. Therefore, the amount of toner attached to the electrostatic latent image collected by the second magnetic brush developing device 8B is extremely small, and a clear toner image 10b is obtained.

(2) Transfer stage The developed toner image 10b is electrostatically transferred to the recording paper 21 by the electric field of the transfer roller 22, and a toner image 24 transferred to the recording paper 21 is obtained.

■Fixing stage The toner image 24 transferred to the recording paper 21 is transferred to the heat fixing device 25.
The image is fixed on the recording paper 21 to obtain a semi-permanent recorded image 26.

(2) Static Elimination/Cleaning Step On the other hand, the charges of the electrostatic latent image and residual toner 27a remaining on the photosensitive drum 20 after the toner image transfer are eliminated using the static eliminating light source 28.

[0126] The residual toner 27b, which has been neutralized, is absorbed by the magnetic force of the magnetic brush developing machines 2B, 8B and the developer 4.
is scraped off, collected by the electrostatic force generated by the recording voltages 3b and 9b, and reused for development.

That is, the collection of the residual toner 27b is as follows:
This is done simultaneously with the next image formation. Note that even if the collection of the residual toner 27b and the next image formation are performed at the same time, the photosensitive drum 20
An image exposure means 5a and two magnetic brush developing machines 2 are sandwiched between
Since B and 8B are in opposing positions, this can be done without any problems.

4) Results of implementation [0128] In this example, no corona discharger was used, which generates ozone that is harmful to the human body and requires a high voltage of several kV. Furthermore, since it is a simple recording process with fewer steps than the Carlson process, it is possible to downsize the image forming apparatus.

[0129] Furthermore, the charge generation layer 20c of the photosensitive drum 20
and the charge transport layer 20d are stacked in the opposite direction to that of conventional photosensitive drums, so the recorded image 26 formed on the recording paper 21 had a high print density and was clear.

5) Configuration Variations In the image forming/recording process described in 2) above, toner image 1
0b Residual toner 2 remaining on the photosensitive drum 20 after transfer
7a and 27b were collected using magnetic brush developing machines 2B and 8B.

However, the residual toner 2 on the photosensitive drum 20
A configuration and process in which 7a and 27b are removed using a brush cleaner, a blade cleaner, or the like is also possible.

Furthermore, the toner image 10b may be transferred onto the recording paper 21 by the corona transfer method instead of the roller transfer method.

It should be noted that this embodiment can also be applied to not only image recording devices such as printers, but also to display devices that directly view the toner image on the photoreceptor without providing a transfer step, to obtain good results. Can be done.

Further, in this embodiment, a case has been described in which magnetic brush developing machines 2B and 8B using two-component developer 4 are used, but conductive magnetic toner can also be used as the developer. It is also possible to use a developing machine that uses non-magnetic insulating toner or magnetic insulating toner.

(2) Example-2 FIG. 4 is a diagram explaining Example-2, in which (a) is a model diagram of an image forming apparatus, and (b) is a perspective view of a developing machine. Note that (a) is a view of the photosensitive drum viewed from the direction of its rotation axis.

1) Configuration The configuration of this embodiment is basically the same as that of embodiment-1. The only difference is the configuration of the developing device 12. That is,
Developing machine 12 with one stage configuration of magnet roller 12a
are using.

The developing device 12 has a magnet roller 12a rotatably provided inside a sleeve 12b. Furthermore, a strip-shaped recording electrode 14 made of copper foil insulated with a polyimide film 13 is attached to the surface of the sleeve 12b.

[0138] Then, a developer 4 containing a mixture of a conductive carrier and an insulating toner is filled, and the magnetic roller 12a is
By rotating the developer 4 in the direction of the arrow in the figure,
This is a mechanism for conveying the material in the direction of the arrow in the figure.

[0139] Similarly to Example-1, the photosensitive drum 20
A hole transfer type photoconductive layer is used for the photoconductive layer. Therefore, a positive recording voltage 16b is applied to the recording electrode 14, and the sleeve 12
A negative recording voltage 17b is applied to b.

By the way, the recording voltage 16b is +1
00 to +600 V, recording voltage 17b is 0 to +600 V
-100 V is suitable.

2) Operation (image formation and image recording procedure)
The image forming/recording procedure is also the same as in Example-1. The difference is that the first development is performed at the opposing portion between the recording electrode 14 and the photosensitive drum 20, and the second development is performed at the opposing portion between the sleeve 12b and the photosensitive drum 20, that is, the developer 4 accumulating portion 18.
This is the point to be made in . Therefore, equivalent results can be obtained as a result of implementation.

(3) Example-3 FIG. 5 is a model diagram explaining Example-3. Note that this figure is a view of the developing machine viewed from the direction of its rotation axis.

The configuration of this embodiment is basically the same as that of embodiment-2. The only difference is that a photosensitive film 29 is used instead of the photosensitive drum 20.

[0144] That is, the image exposure means 5b and the developing machine 12
A are arranged facing each other with the photoreceptor film 29 in between, and in the process order are a transfer roller 22a, a heat fixing device 25a,
A static elimination light source 28a is arranged.

A guide plate 31 made of glass is disposed at a position where the photoreceptor film 29 is irradiated with the image light of the image exposure means 5b, so that the focal position of the image light does not change.

[0146] Also, the first recording voltage 16c and the second
The recording voltage 17c and transfer voltage (power supply) 23a are also the same as in Example-2.

The drive roller 30 is rotated in the direction of the arrow in the figure by a power system not shown. Therefore, the photoreceptor film 29 sandwiched between the drive roller 30 and the transfer roller 22a is conveyed in the direction of the arrow in the figure and rotated once by each guide roller.

By the way, the photoreceptor film 29 has a thickness of
A photosensitive layer similar to that in Example 1 was formed on a 100 μm transparent polyethylene terephthalate substrate.

That is, a transparent conductive layer of ITO (indium tin oxide) vapor deposited film is provided on polyethylene terephthalate, and a charge transport layer and a charge generation layer are laminated as a photoconductive layer. Then, a surface protective layer is laminated for the purpose of protecting the mechanically weak charge generation layer. Incidentally, the thickness of the functionally separated organic photoreceptor described above is about 20 μm.

[0150] In this example as well, an excellent recorded image 26a with high development density and clarity, which is equivalent to Example-1 and Example-2, was obtained.

[0151]

As described above, according to the image forming apparatus of the present invention, the second The latent image charges no longer move during the development process.

[0152] Therefore, it becomes possible to obtain a clear image with high development density (image density).

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the basic principle (1) of the present invention, in which (a) is a diagram showing the configuration of a developing device, (b) is a diagram showing the configuration of a photoreceptor, and (c) and (d) are diagrams showing the configuration of a photoreceptor. FIG. 3 is a diagram showing the operating principle.

[Fig. 2] Diagrams explaining the basic principle (2) of the present invention, in which (a) is a diagram showing the configuration of a developing device, (b) is a diagram showing the configuration of a photoreceptor, and (c) and (d) are diagrams showing the configuration of a photoreceptor. FIG. 3 is a diagram showing the operating principle.

FIG. 3 is a diagram illustrating Example-1, in which (a) is a model diagram of an image forming apparatus, (b) is a diagram showing the configuration of a photoreceptor,
It is. Note that (a) is a view of the photosensitive drum viewed from the direction of its rotation axis.

FIG. 4 is a diagram illustrating Example 2, in which (a) is a model diagram of an image forming apparatus, and (b) is a perspective view of a developing machine. Note that (a) is a view of the photosensitive drum viewed from the direction of its rotation axis.

FIG. 5 is a model diagram explaining Example-3. Note that this figure is a view of the developing machine viewed from the direction of its rotation axis.

FIG. 6 is a model diagram explaining an image forming apparatus and its principle (1), in which (a) is a diagram showing the configuration, and (b) and (c) are diagrams explaining the principle. In this figure, the developing device has a roller-like shape, and this figure is a view seen from the axial direction.

FIG. 7 is a model diagram explaining an image forming apparatus and its principle (2), in which (a) is a diagram showing the configuration, and (b) and (c) are diagrams explaining the principle. In this figure, the developing device has a roller-like shape, and this figure is a view seen from the axial direction.

[Explanation of symbols]

Claims (3)

[Claims] 1. A photoreceptor (1) formed by laminating a transparent substrate (1a), a transparent or translucent conductive layer (1b), and a photoconductive layer (1c), and a photoconductive layer of the photoreceptor (1). (
1c), a first developing means (2A) filled with a developer (4), and a first voltage applying means (3a) for applying a voltage to the first developing means (2A); an image exposing means (5) provided on the transparent substrate (1a) side of the photoreceptor (1) and at a position facing the first developing means (2A) and performing image exposure based on image data; A second developing means (8A) disposed downstream of the first developing means (2A) in the direction of movement of the photoreceptor (1) and the first voltage applying means (3) apply voltages of opposite polarity. , a second voltage applying means (9a) applied to the second developing means (8A);
), an image forming apparatus comprising: the photoreceptor (1);
), at least a transparent substrate (19a), a transparent or translucent conductive layer (19b), and a charge transport layer (19).
c) An image forming apparatus characterized by using a photoreceptor (19) in which a charge generation layer (19d) is sequentially laminated. 2. A photoreceptor (1) formed by laminating a transparent substrate (1a), a transparent or translucent conductive layer (1b), and a photoconductive layer (1c), and a photoconductive layer of the photoreceptor (1). (
1c) side and filled with developer (4), and a sleeve (12b) of the magnetic brush developing machine (12), provided on the sleeve (12b) insulated from the sleeve (12b). a recording electrode (14), and a recording electrode (14)
4) and a first voltage application that applies a voltage to the developer (4) accumulating portion (18) provided on the downstream side in the moving direction of the photoreceptor (1) and the recording electrode (14). means (16a); and the first voltage application means (16a).
a second voltage applying means (17a) for applying a voltage of opposite polarity to the sleeve (12b);
1) on the transparent substrate (1a) side and the recording electrode (1a)
4), and an image exposure means (5) that performs image exposure based on image data, the photoreceptor (1) having at least:
Transparent substrate (19a), transparent or translucent conductive layer (1
9b), charge transport layer (19c), charge generation layer (19)
d) using a photoreceptor (19) in which the following are sequentially laminated;
An image forming apparatus characterized by: 3. The image forming apparatus according to claim 1 and claim 2, wherein a photoreceptor is used in which a surface protective layer for protecting the charge generation layer (19d) is provided on the charge generation layer (19d); An image forming apparatus characterized by: