JP2640697B2 - Image forming device - Google Patents

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 which simultaneously performs image exposure from one surface of a photoconductor and develops the other surface to obtain a toner image on the photoconductor.

An image forming apparatus using an electrophotographic recording method is generally used as a copying machine or a high-speed, high-print-quality printer.

[0003] The electrophotographic recording method is a method in which a photosensitive member is used as a recording medium and recording is performed from each step of uniform charging → image exposure → development → transfer → fixing → static elimination → cleaning. is there.

[0004] In the Carlson process, a corona discharger is used for uniform charging, transfer, and charge elimination.

However, since the corona discharger is configured to apply a high voltage of several kV to the corona wire, it requires a high-voltage power supply and is easily affected by humidity, dust, and the like.
There is a disadvantage of low reliability.

[0006] Further, the ozone generated in the corona discharger generates odor, and the ozone is harmful to the human body.

On the other hand, in the Carlson process, the above seven steps are necessary for image formation, and therefore, there are disadvantages that the image forming apparatus becomes complicated and the apparatus becomes large.

On the other hand, considering these problems, an image forming method and an image forming apparatus have been proposed which focus on miniaturization of the apparatus without using a corona discharger.

More specifically, there is provided an image forming method and an image forming apparatus in which a toner developing machine and an image exposing means are arranged opposite to each other with a photoreceptor interposed therebetween to simultaneously perform image exposing and developing. The present invention relates to the image forming apparatus, and is an invention made to improve image density.

[0010]

2. Description of the Related Art As an image forming apparatus in which a toner developing machine and an image exposing means are opposed to each other with a photoreceptor interposed therebetween to perform image exposure and development at the same time, there are an apparatus having two stages of developing machines and one having only one stage. There is. However, the principle is the same for both image forming apparatuses. Here, both devices will be described separately.

(1) Image Forming Apparatus with Two Stages of Developing Machine FIG. 6 is a model diagram for explaining the image forming apparatus and its principle (1), (a) is a diagram showing the configuration, and (b) (c) ) Is a diagram for explaining the principle. In the figure, the developing machine has a roller-like shape, and the figure is viewed from the axial direction.

1) Structure The photoconductor 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 the ground.

On the other hand, the first magnetic brush developing machine 2 provided on the photoconductive layer 1c side of the photoreceptor 1 comprises a magnet roller 2a and a sleeve 2b, and both the magnet roller 2a and the sleeve 2b are rotatable. doing.

A voltage 3 having a polarity opposite to the polarity (positive in the figure) of the electric charge moving in the photoconductive layer 1c is applied to the first magnetic brush developing machine 2. Here, this voltage is referred to as a first recording voltage 3.

Then, the first magnetic brush developing machine 2
Is filled with a one-component or two-component developer 4, and the developer 4 is transported by the rotation of the magnet roller 2a and the sleeve 2b.

On the other hand, an image exposure means 5 is provided at a position on the transparent substrate 1a side of the photosensitive member 1 and at a position facing the first magnetic brush developing machine 2. Incidentally, the image exposure means 5 includes an LED array optical system, a laser optical system, an EL optical system,
A liquid crystal shutter optical system or the like can be used.

Next, a second magnetic brush developing machine 8 is provided downstream of the first magnetic brush developing machine 2 in the moving direction of the photosensitive member 1. The second magnetic brush developing device 8 includes a magnet roller 8a and a sleeve, similarly to the first magnetic brush developing device 2.
8b, and both the magnet roller 8a and the sleeve 8b are rotatable.

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

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

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

2) Principle of Image Formation Image Exposure and First Development When image exposure is performed by irradiating photoreceptor 1 with light 11 from image exposure means 5, electron-hole pairs are formed in photoconductive layer 1c of photoreceptor 1. Occurs.

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

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

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

Second Development Next, the photosensitive member 1 after the first development is moved upward in the drawing, that is, to the second magnetic brush developing machine 8.

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 machine 8.

For this reason, of the toner adhered in the first magnetic brush developing device 2, the excess toner in the non-exposed portion can be collected by electrostatic force.

At this time, the toner in the exposed portion is also slightly recovered, 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 the toner image 10 can be formed. Here, this step is referred to as second development.

(2) Image Forming Apparatus with One Stage of Developing Machine FIG. 7 is a model diagram for explaining the image forming apparatus and its principle (2), (a) is a diagram showing the configuration, and (b) and (c). Is a diagram for explaining the principle. In the figure, the developing machine has a roller-like shape, and the figure is viewed from the axial direction.

1) Configuration The configuration of the photoreceptor 1 and the configuration of the exposure means 5 are as described in (1) above.
Is the same as Further, the developing device 12 is disposed at a position opposite to the exposure unit 5 with the photoconductor 1 interposed therebetween.

A developing device 12 provided on the photoconductive layer 1c side of the photosensitive member 1
Consists of a magnet roller 12a and a sleeve 12b,
The magnet roller 12a is rotatable.

Further, on the surface of the sleeve 12b, a band-shaped recording electrode insulated from the sleeve 12b by an insulating film 13.
14 are provided.

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

On the other hand, a voltage 17 having a polarity opposite to that of the recording electrode 14 is applied to the sleeve 12b. That is, the second recording voltage 17
It is.

Further, the developing device 12 is filled with a developer or a conductive magnetic toner 4 in which a conductive carrier and an insulating toner are mixed, and is transported in the direction of the arrow in the figure.

2) Principle of Image Formation Image Exposure and First Development At a portion where the recording electrode 14 and the photoreceptor 1 face each other, that is, a portion A in FIG. When image exposure is performed, electron-hole pairs are generated in the photoconductive layer 1c of the photoconductor 1.

On the other hand, the recording electrode 14 has a negative first recording voltage.
Since 16 (−100 to −600 V) is applied, the positively-charged holes of the electron-hole pairs move to the vicinity of the surface of the photoconductive layer 1 c of the photoreceptor 1 to form latent image charges 6. .

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

That is, the toner image 10 having a certain degree of contrast is formed between the exposed portion and the non-exposed portion, and the first development is completed.

Second Phenomenon The downstream side of the recording electrode 14 in the moving direction of the photosensitive member 1, that is, FIG.
In part B of FIG. 5A, since the transport direction of the developer 4 and the moving direction of the photoconductor 1 are opposite to each other, a pool 18 of the developer 4 occurs.

Incidentally, a recording voltage 17 (0 to +100 V) having a polarity opposite to that of the first recording voltage 16 is applied to the sleeve 12b.

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

At this time, the toner in the exposed portion is also slightly recovered, but most of the toner remains on the photosensitive member 1 due to the electrostatic binding force of the latent image charge 6 and the toner charge, and the toner image 10 can be formed. That is, the second development is completed.

[0044]

However, the above (1)
And (2) in the second developing step of the image forming apparatus,
In the first developing step, the toner attached to the latent image charges 6 may be collected too much, and the development density (image density) may decrease. Next, the details will be described.

(1) In the case of an image forming apparatus provided with two stages of developing machines (see FIGS. 6B and 6C) In FIGS. 6B and 6C, a function-separated type photosensitive member 1 is assumed as the photosensitive member. 4 shows the recording process performed.

The function-separated type photoreceptor 1 has at least a transparent substrate 1a and a transparent conductive layer 1b, a charge generating layer 1d for generating electron-hole pairs by image exposure, and a charge for transporting charges generated in the charge generating layer 1d. The transport layer 1e is sequentially laminated.
That is, it is a photoconductor in which the photoconductive layer 1c is composed of the charge generation layer 1d and the charge transport layer 1e.

When such a photosensitive member 1 is used, FIG.
(b) As shown in FIG.
The electron-hole pairs generated therein move due to the electric field formed by the recording voltage 3. That is, holes having a positive charge are
It moves toward the surface of the photoreceptor 1 through the charge transport layer 1e to form a latent image charge 6, and electrons having a negative charge 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 do not move to the charge transport layer.

That is, since the boundary surface between the charge transport layer 1e and the charge generation layer 1d forms a block layer (barrier), a positive charge can pass through the interface but a negative charge cannot.

Next, in the second developing unit 8 for collecting the toner in the non-exposed portion, that is, the background portion, as shown in FIG. 6C, a toner collecting electric field is applied to the charge transport layer 1e by the recording voltage 9. .

Therefore, the positive latent image charges 6 move in some cases. That is, the latent image charge 6 on the surface of the photoconductor 1 moves to the conductive layer 1b side of the photoconductor 1 again, and weakens the adhesion of the toner on the surface of the photoconductor 1.

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

(2) An image forming apparatus having a single-stage developing machine (FIG. 7)
(See (b) and (c)) In the case of the present apparatus, the image density is reduced for the same reason as in the above (1).

That is, as shown in FIG. 7 (b), the positive latent image charge 6 of the portion A formed by the image exposure and the recording voltage 16 applied to the recording electrode 14 is shown in FIG. 7 (c). As described above, the portion B moves to the conductive layer 1b side to weaken the adhesion of the toner on the surface of the photoconductor 1.

As a result, the amount of toner adhering to the latent image on the photosensitive member 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 prevent or prevent the latent image charge from moving in the second developing step, so that the developing density is reduced. An object of the present invention is to realize an image forming apparatus having a high (image density) and obtaining a clear image.

[0057]

FIGS. 1A and 1B are diagrams for explaining the basic principle (1) of the present invention. FIG. 1A shows the structure of a developing device, and FIG. 1B shows the structure of a photoreceptor. Figures (c) and (d) are diagrams illustrating the principle of operation.

FIGS. 2A and 2B are views for explaining the basic principle (2) of the present invention. FIG.
(b) is a diagram showing the configuration of the photoconductor, and (c) and (d) are diagrams showing the operation principle.

In the present invention, the charge generation layer 19d and the charge transport layer 19
The feature is that the stacking order of c is reversed from the conventional order.

(1) Image Forming Apparatus with Two Stages of Developing Machine (See FIG. 1) An image forming apparatus having the following constitutional requirements is assumed.

A photoconductor 1 comprising a transparent substrate 1a, a transparent or translucent conductive layer 1b, and a photoconductive layer 1c is laminated.

The first developing means 2A which is disposed on the photoconductive layer 1c side of the photosensitive member 1 and is filled with the developer 4

A first method for applying a voltage to the first developing means 2A
Voltage applying means 3a

An image exposing means 5 which is provided on the transparent substrate 1a side of the photoreceptor 1 and is opposed to the first developing means 2A, and performs image exposure based on image data.

The second developing means 8A arranged on the downstream side of the first developing means 2A in the moving direction of the photosensitive member 1

Second voltage applying means 9a for applying a voltage having a polarity opposite to that of the first voltage applying means 3 to the second developing means 8A.

In the image forming apparatus having the above-mentioned structure, at least the transparent substrate 19a and the transparent or translucent conductive layer 19 are used as the photosensitive member 1.
b, a charge transport layer 19c, and a charge generating layer 19d, and a photosensitive member 19 in which a charge generating layer 19d is sequentially laminated.
The polarity of the first voltage applying means 3a for applying a voltage to the charge generation layer 19d on the surface side passes through the boundary between the charge generation layer 19d and the charge transport layer 19c.
And the polarity of the second voltage applying means 9a for applying a voltage to the second developing means 8A is the same as that of the charges movable in the direction of the conductive layer 19b.
The image forming apparatus is characterized in that it has the same polarity as the latent image charge 6a that remains at 9d and cannot pass through the boundary surface.

(2) Image Forming Apparatus with One Stage of Developing Machine (See FIG. 2) An image forming apparatus having the following constitutional requirements is assumed.

A photoconductor 1 comprising a transparent substrate 1a, a transparent or translucent conductive layer 1b, and a photoconductive layer 1c laminated on each other.

A magnetic brush developing machine 12 arranged on the photoconductive layer 1c side of the photoconductor 1 and filled with the developer 4

A recording electrode 14 provided on a sleeve 12b of the magnetic brush developing machine 12 insulated from the sleeve 12b.

The photosensitive member 1 approaches the recording electrode 14 and
Of the developer 4 provided on the downstream side in the moving direction of the developer 4.

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

Second voltage applying means for applying a voltage having a polarity opposite to that of the first voltage applying means 16a to the sleeve 12b.
17a

An image exposure means 5 which is 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 above-mentioned structure, at least the transparent member 19a, the transparent or translucent conductive layer 19
b, the charge transport layer 19c and the charge generation layer 19d are sequentially stacked, and the photoconductor 19 is used. The polarity of the first voltage applying means 16a for applying a voltage to the recording electrode 14 is the same as that of the charge generation layer 19d. Applying a voltage to the sleeve 12b, which has the same polarity as the charge that can move in the direction of the conductive layer 19b from the charge generation layer 19d on the surface side through the boundary surface with the charge transport layer 19c. The image forming apparatus is characterized in that the polarity of the second voltage applying means 17a is the same as the polarity of the latent image charges 6a that remain in the charge generation layer 19d and cannot pass through the boundary surface.

(3) Image Recording Apparatus Having Protective Layer Provided on Photoconductor That is, in the image forming apparatus of (1) and (2), a surface protective layer for protecting charge generating layer 19d is replaced with charge generating layer 19d. This is an image forming apparatus using the photoconductor provided above.

[0078]

The above-mentioned means (1) and (2) differ in the configuration of the image forming apparatus on which they are premised, but have the same image forming principle. Further, the configuration of the photoconductor 19 used in the image forming apparatus is the same.

(1) Image Forming Apparatus Where Two Stages of Developing Machines are Installed (See FIGS. 1C and 1D) The photosensitive member 19 used in the image forming apparatus of the present invention is shown in FIG.
Compared with the conventional photoreceptor 1 shown in FIG. 7C and FIGS. 7B and 7C, the present embodiment is characterized in that the stacking order of the charge generation layer 19d and the charge transport layer 19c is reversed.

The polarity of the voltage applying means 3a for applying the recording voltage to the first developing means 2A and the polarity of the voltage applying means 9a for applying the recording voltage to the second developing means 8A are shown in FIGS.
Is opposite to the conventional image forming apparatus shown in FIG.

As a result, the latent image charge formed in the first development
6a does not move in the second development, and an image with high print density is obtained. The details will be described below.

That is, in the first development, as shown in FIG. 1C, when the image exposure is performed by irradiating the photoreceptor 19 with light 11 from the image exposure means 5, the charge generation layer 19d of the photoreceptor 19 is exposed. An electron-hole pair is generated inside.

On the other hand, a positive recording voltage is applied to the first developing means 2A.
Since 3a is applied, holes having a positive charge among the electron-hole pairs are charged in the charge transport layer by the strong electric field due to the recording voltage 3a.
Through 19c, it flows into the transparent conductive layer 19b. Further, electrons having negative charges 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 is applied by the recording voltage 9a. The toner in the non-exposed portion, that is, the background portion is collected.

By the way, in the second development, the negatively charged electrons remaining in the charge generation layer 19d, that is, the latent image charges 6
As for a, the interface between the charge generation layer 19d and the charge transport layer 19c cannot pass through 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 toner adhered to the latent image charge 6a becomes difficult to be collected by the second developing means, and the developing density is reduced. Can be kept high.

That is, an 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 through but the other charge cannot pass. It is a point.

Incidentally, in general, in an organic photoreceptor, positive charges (holes) can pass through the interface but negative charges (electrons) cannot. However, it is also possible to form a blocking layer, ie, a barrier, which works in the opposite manner, by selecting the material of any of the organic and inorganic photoconductive materials.

(2) Image Forming Apparatus Where One Developing Machine is Provided (See FIGS. 2C and 2D) The operation of the present invention is the same as that of the above (1). That is, using the same photoconductor 19 as in the above (1),
The recording voltage applied to the recording electrode 14 and the sleeve 12d, that is, the polarity of the first voltage applying means 16a and the polarity of the second voltage applying means 17a are also the same.

The operation in the first development shown in FIG. 2C and the operation in the second development shown in FIG. 2D are the same.

That is, the latent image charge formed in the first development
6a does not move in the second development, and an image having a high development density can be obtained.

(3) An image recording apparatus provided with a protective layer on a photoreceptor By providing a surface protective layer for protecting the charge generating layer 19d, a toner image is formed on the surface protective layer. Deterioration of the photoreceptor 19
Can be extended.

[0093]

Next, an example of how the image forming apparatus according to the present invention can be actually embodied will be described.

(1) Embodiment 1 FIGS. 3A and 3B are diagrams for explaining Embodiment 1, in which FIG. 3A is a model diagram of an image forming apparatus, and FIG. 3B is a diagram showing a configuration of a photosensitive member.
(A) is a view of the photosensitive drum viewed from the direction of its rotation axis.

1) Structure Photosensitive Drum As shown in FIG. 3B, the photosensitive drum 20 is provided with a transparent conductive layer 20b of an ITO (indium tin oxide) vapor-deposited film on a transparent substrate 20a made of glass. It comprises a charge transport layer 20c and a charge generation layer 20d. That is, it is a function-separated type organic photoreceptor.

Then, a surface protective layer 20e is laminated for the purpose of protecting the mechanically weak charge generating layer 20d. Incidentally, the thickness of the photoreceptor is about 20 μm.

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

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

First Magnetic Brush Developing Machine The first magnetic brush developing machine 2B comprises an inner magnet roller and an outer sleeve, and the sleeve is rotatable.

Then, 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, a first recording voltage 3b is applied to the developing device 2B.

Incidentally, the photoconductive layers 20c, 2c of this embodiment
For 0d, a hole transfer type was used. Therefore, a positive polarity recording voltage 3b is applied to the first magnetic brush developing machine 2B. Incidentally, +100 to +600 V is appropriate as the recording voltage 3b.

Then, the first magnetic brush developing machine 2B
And a developer 4 in which a conductive carrier and an insulating toner are mixed.
And transported by rotation of the sleeve.

Image Exposure Means The image exposure means 5a is arranged at a position opposite to the first magnetic brush developing machine 2B with the photosensitive drum 20 interposed therebetween.

Incidentally, the image exposing means 5a comprises an LED array which emits light in accordance with an image signal and a selfoc lens array which condenses the image light of the LED array.

Incidentally, the toner image 7b on the photosensitive drum 20 is in a state where the toner is also attached to the non-exposed portion, that is, the background portion.

Second Magnetic Brush Developing Machine The second magnetic brush developing machine 8B is a first magnetic brush developing machine.
As viewed from 2B, it is provided downstream of the photosensitive drum 20 in the rotation direction.

Further, the second magnetic brush developing machine 8B
Like the magnetic brush developing machine 2B, the magnetic brush developing device 2B includes a magnet roller and a sleeve, and the sleeve is rotatable.

Then, the second magnetic brush developing machine 8B has:
A recording voltage having a polarity opposite to that of the first recording voltage 3b, that is, a second recording voltage 9b is applied. Incidentally, the recording voltage 9b is 0 V
~ -100V is suitable.

The second magnetic brush developing device 8B is filled with the same developer 4 as the developer charged in the first magnetic brush developing device 2B, and is conveyed by rotating the sleeve.

Transfer Roller The transfer roller 22 is formed 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. When the recording sheet 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 sheet. Transfer to 21.

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

The charge elimination light source 28 is a device for removing the latent image charges in the charge transport layer 20c and the charge generation layer 20d of the photosensitive drum 20 by uniformly exposing the photosensitive drum 20 to light. At this time, the charge of the residual toner 27a attached to the photosensitive drum 20 can be removed at the same time.

2) Photoconductive Material of Photosensitive Drum The photoconductive material of the photosensitive drum 20 includes organic materials such as phthalocyanine-based materials, PVK-TNF, azo-based dyes, and thiapyrylium dyes. ,
a-Si, CdS, zinc oxide and the like can be used.

The above organic 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 a boundary surface (barrier) through which only charges of either polarity can pass.
By the way, in this embodiment, it was formed so that only positive charges could pass.

3) Operation (Image formation and image recording procedure) An image is formed and recorded by the following procedures (1) to (4).

Image exposure stage The photosensitive drum 20 is rotated and transported 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 to convey the respective developer 4 in the direction of the arrow in the figure.

Then, the first and second recording voltages 3b, 9b
Is applied, and the photosensitive drum 20 is
Is image-exposed.

Developing Step When the image exposure is performed, the charge generation layer 20 d of the photosensitive drum 20 is formed.
Then, electron-hole pairs are generated, and holes flow into the transparent conductive layer 20b through the charge transport layer 20c, while electrons stay in the charge generation layer 20d to form latent image charges.

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

Then, the photosensitive drum 20 rotates sequentially, and excess toner attached to the non-exposed portion of the toner image 7b is collected by the electrostatic force of the second magnetic brush developing device 8B (second development).

Incidentally, in the photosensitive drum 20 of this embodiment,
The electrostatic latent image on the photosensitive drum 20 is transferred to a second magnetic brush developing machine.
8B does not weaken. 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.

Transfer Step 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 Step The toner image 24 transferred to the recording paper 21 is fixed on the recording paper 21 by the heat fixing device 25, and a semi-permanent recording image 26 is obtained.

[0125] On the other hand, the charge of the electrostatic latent image remaining on the photosensitive drum 20 after the transfer of the toner image and the charge of the residual toner 27a are removed by the charge removing light source 28.

Then, the residual toner 27b from which the charge has been removed is collected by the magnetic force of the magnetic brush developing machines 2B and 8B, the scraping of the developer 4, and the electrostatic force by the recording voltages 3b and 9b.
Reuse for development.

That is, the recovery of the residual toner 27b is performed simultaneously with the next image formation. Even if the recovery of the residual toner 27b and the next image formation are performed at the same time, since the image exposure means 5a and the two magnetic brush developing machines 2B and 8B are located opposite to each other with the photosensitive drum 20 therebetween, there is no problem. It can be carried out.

4) Implementation Results In this embodiment, no corona discharger which generates harmful ozone to the human body and requires a high voltage of several kV is used. Since the number of steps is smaller than that of the Carlson process and the printing process is simple, the size of the image forming apparatus can be reduced.

The charge generation layer 20d of the photosensitive drum 20
And the charge transport layer 20c are laminated on the opposite side of the conventional photosensitive drum, so that the recorded image 26 formed on the recording paper 21 has a large print density and is clear.

5) Structural Variation In the image forming / recording process described in 3), the residual toner 27a, 27b remaining on the photosensitive drum 20 after the transfer of the toner image 10b is removed from the magnetic brush developing machines 2B, 8B.
Collected in B.

However, the residual toner 27a,
A configuration and process for removing 27b with a brush cleaner, a blade cleaner, or the like is also possible.

Further, the transfer of the toner image 10b to the recording paper 21 may be performed by a corona transfer method without depending on the roller transfer method.

The present embodiment can obtain good results even when applied to a display device for directly viewing a toner image on a photoreceptor without a transfer step, in addition to an image recording device such as a printer. Can be.

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

(2) Embodiment-2 FIGS. 4A and 4B are diagrams illustrating Embodiment-2, wherein FIG. 4A is a model diagram of an image forming apparatus, and FIG. 4B is a perspective view of a developing machine. still,
(a) is a diagram 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 machine 12. That is, the developing device 12 having the one-stage magnet roller 12a is used.

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

Then, the developer 4 mixed with the conductive carrier and the insulating toner is charged, and the magnet roller 12a is rotated in the direction of the arrow in the figure to convey the developer 4 in the direction of the arrow in the figure. is there.

As in the case of Example 1, the photoconductive layer of the photosensitive drum 20 uses a hole transfer type. Therefore, a positive recording voltage 16b is applied to the recording electrode 14, and a negative recording voltage 17b is applied to the sleeve 12b.

By the way, the recording voltage 16b is from +100 to
+600 V and 0 to -100 V are suitable as the recording voltage 17b.

2) Operation (Image Forming and Image Recording Procedure) The image forming / recording procedure is the same as that of the first embodiment. The difference is that the first development is performed on the opposing portion between the recording electrode 14 and the photosensitive drum 20, and the second development is performed on the sleeve 12b and the photosensitive drum 20.
This is performed in a portion opposed to the above, that is, in a pool portion 18 of the developer 4. Therefore, an equivalent result is obtained as an execution result.

(3) Embodiment-3 FIG. 5 is a model diagram for explaining Embodiment-3. FIG. 1 is a view of the developing device as viewed from the direction of its rotation axis.

The configuration of the present embodiment is basically the same as that of Embodiment 2. The only difference is that a photosensitive film 29 is used in place of the photosensitive drum 20.

That is, the image exposure means 5b and the developing machine 12A
Are arranged to face each other with the photosensitive film 29 interposed therebetween, and a transfer roller 22a, a heat fixing device 25a, and a static elimination light source 28a are arranged in the order of process.

A guide plate made of glass is provided at a position where the image light of the image exposure means 5b is irradiated on the photosensitive film 29.
31 is arranged so that the focal position of the image light does not change.

The first recording voltage 16c, the second recording voltage 17c, and the transfer voltage (power supply) 23a are the same as those in the embodiment-2.

The drive roller 30 is rotated in the direction of the arrow by a power system (not shown). For this reason, the photosensitive 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 is rotated once by each guide roller.

The photosensitive film 29 has a thickness of 100 mm.
The same photosensitive layer as in Example 1 was formed on a transparent substrate of polyethylene terephthalate having a thickness of μm.

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

Also in this embodiment, a clear and excellent recorded image 26a having a high developing density and the same level as in Embodiments 1 and 2 is obtained.

[0151]

As described above, according to the image forming apparatus of the present invention, the first development is performed by using the photoconductor in which the charge generation layer and the charge transport layer are reversely laminated as compared with the conventional photoconductor. The polarity of the first voltage applying means for applying a voltage to the means is defined as a charge that passes through the interface between the charge generation layer and the charge transport layer and is movable from the charge generation layer on the surface side toward the conductive layer. The same polarity and the polarity of the second voltage applying means for applying a voltage to the second developing means have the same polarity as that of the latent image charges which remain in the charge generation layer and cannot pass through the boundary surface. In the developing step 2, the latent image charge does not move.

Therefore, a clear image having a high development density (image density) can be obtained.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams for explaining the basic principle (1) of the present invention, in which FIG. 1A shows a configuration of a developing device, FIG. 1B shows a configuration of a photoreceptor, and FIGS. It is a figure showing an operation principle.

FIGS. 2A and 2B are diagrams for explaining the basic principle (2) of the present invention. FIG. 2A is a diagram showing a configuration of a developing device, FIG. 2B is a diagram showing a configuration of a photoconductor, and FIGS. It is a figure showing an operation principle.

FIGS. 3A and 3B are diagrams illustrating Example 1, wherein FIG. 3A is a model diagram of an image forming apparatus, and FIG. 3B is a diagram illustrating a configuration of a photoconductor.
(A) is a view of the photosensitive drum viewed from the direction of its rotation axis.

4A and 4B are diagrams illustrating Example-2, in which FIG. 4A is a model diagram of an image forming apparatus, and FIG. 4B is a perspective view of a developing device. still,
(a) is a diagram of the photosensitive drum viewed from the direction of its rotation axis.

FIG. 5 is a model diagram illustrating Example-3; FIG. 1 is a view of the developing device as viewed from the direction of its rotation axis.

FIGS. 6A and 6B are model diagrams illustrating an image forming apparatus and its principle (1), wherein FIG. 6A is a diagram illustrating a configuration, and FIGS. 6B and 6C are diagrams illustrating the principle. In the figure, the developing machine has a roller-like shape, and the figure is viewed from the axial direction.

FIGS. 7A and 7B are model diagrams illustrating an image forming apparatus and its principle (2), wherein FIG. 7A is a diagram illustrating a configuration, and FIGS. 7B and 7C are diagrams illustrating the principle. In the figure, the developing machine has a roller-like shape, and the figure is viewed from the axial direction.

[Explanation of symbols]

 1,19 Photoreceptor 1a, 19a Transparent substrate 1b, 19b Transparent conductive layer 1c Photoconductive layer 1d, 19d Charge generation layer 1e, 19c Charge transport layer 2,2A, 2B First developing machine 2a, 8a, 12a Magnet roller 2b , 8b, 12b Sleeve 4 Developer 5,5a, 5b Image exposure means 6,6a Latent image charge (electrostatic latent image) 7,7a, 7b Toner image 8,8A, 8B Second developing machine 10,10a, 10b , 10c Toner image 11 Light (image light) 12,12A Developing machine 13 Insulating film 14,14a Recording electrode 15 Toner image 18 Storing portion of developer 20 Photosensitive drum 20a Transparent substrate 20b Transparent conductive layer 20c Charge transport layer 20d Charge generation layer 20e Surface protective layer 21 Recording paper 22,22a Transfer roller 24,24a Toner image 25,25a Thermal fixing device 26,26a Recorded image 27a, 27b, 27c, 27d Residual toner 28,28a Static electricity elimination light source 29 Photoconductor film 30 Drive roller 31 Guide plate

Claims (3)

(57) [Claims] 1. A photoconductor (1) comprising a transparent substrate (1a), a transparent or translucent conductive layer (1b), and a photoconductive layer (1c), and a photoconductive layer of the photoconductor (1). A first developing unit (2A) arranged on the (1c) side and filled with a developer (4); a first voltage applying unit (3a) for applying a voltage to the first developing unit (2A); An image exposure unit (5) provided on the transparent substrate (1a) side of the photoconductor (1) and facing the first developing unit (2A), and performing image exposure based on image data; A second developing unit (8A) disposed downstream of the first developing unit (2A) in the moving direction of the photoconductor (1); and a voltage having a polarity opposite to that of the first voltage applying unit (3a). To
And a second voltage applying means (9a) for applying to the second developing means (8A), wherein at least a transparent substrate (19) is used as the photoconductor (1).
a) using a photoconductor (19) in which a transparent or translucent conductive layer (19b), a charge transport layer (19c), and a charge generation layer (19d) are sequentially laminated, and the first developing means (2A) Applying the voltage to the first
The polarity of the voltage applying means (3a) is the same as that of the charge generation layer (1).
9d) and the charge transport layer (19c).
From the charge generation layer (19d) on the surface side.
Of the same polarity as the charge movable in the direction of the electric layer (19b).
And applying the voltage to the second developing means (8A).
The polarity of the voltage applying means (9a) is the same as that of the charge generation layer (1).
9d), the latent image charge which cannot pass through the boundary surface
An image forming apparatus having the same polarity as the load (6a) . 2. A photoconductor (1) comprising a transparent substrate (1a), a transparent or translucent conductive layer (1b), and a photoconductive layer (1c), and a photoconductive layer of the photoconductor (1). A magnetic brush developing machine (12) arranged on the (1c) side and filled with a developer (4); and a sleeve (12b) of the magnetic brush developing machine (12) insulated from the sleeve (12b). The provided recording electrode (14), the recording electrode (14), and the photoconductor (1)
Of the developer (4) provided on the downstream side in the movement direction of the developer (4).
8), first voltage applying means (16a) for applying a voltage to the recording electrode (14), and a voltage having a polarity opposite to that of the first voltage applying means (16a) is applied to the sleeve (12b). A second voltage applying means (17a) to be applied, provided at a position on the transparent substrate (1a) side of the photoconductor (1) and opposed to the recording electrode (14), and performing image exposure based on image data. An image forming apparatus comprising: an image exposing unit (5), wherein at least a transparent substrate (19) is used as the photoconductor (1).
a), a photoconductor (19) in which a transparent or translucent conductive layer (19b), a charge transport layer (19c), and a charge generation layer (19d) are sequentially laminated, and a voltage is applied to the recording electrode (14). The first voltage to be applied
The polarity of the application means (16a) depends on the charge generation layer (19).
d) and the charge transport layer (19c)
From the charge generation layer (19d) on the surface side.
Of the same polarity as the charge movable in the direction of the electric layer (19b).
And the second electrode for applying a voltage to the sleeve (12b).
The polarity of the pressure applying means (17a) depends on the charge generation layer (19).
latent image charges that remain in d) and cannot pass through the interface
An image forming apparatus having the same polarity as (6a) . 3. The image forming apparatus according to claim 1, wherein a photoconductor provided with a surface protective layer for protecting the charge generation layer (19d) on the charge generation layer (19d) is used. An image forming apparatus comprising: