JPS6221168A - Photosensitive body for electrophotographic device - Google Patents

Abstract

PURPOSE:To set optimum potentials according to respective processes by providing a support body which has plural parts which are sectioned electrically. CONSTITUTION:A photosensitive drum 10 includes the hollow support body 12 and a photoconductive layer 14 formed on its surface. The support body 12 is partitioned into plural parts electrically so that different potentials are set at the same time. One insulating roller 15 is arranged in the center and plural conductive rollers 16, 18, 20, 22, 24, 26, and 28 are arranged around it so that they re rotated by the roller 15. A conductive roller 16 is used to set the potential of the part of the support body 12 in an electrostatic charging process, and connected to an electrostatic charging voltage circuit 30. A conductive roller 18 is used to detect a current flowing in the support body 12 at the part during exposure and connected to a voltage lead-out circuit 32.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a photoreceptor for an electrophotographic apparatus, and particularly to a photoreceptor for an electrophotographic apparatus such as an electrophotographic copying machine or a printer.

(Prior art) In conventional electrophotographic devices or electrostatic recording devices, the potential of the support of the photoreceptor is either grounded or fixed at a constant potential. It's dripping.

(Problem to be Solved by the Invention) For example, when originals have different qualities, such as documents or photographs, it is necessary to develop the former with a strong contrast and the latter with a softer contrast. . In such a case, conventionally, in order to control the amount of toner adhesion, that is, the amount of charge, a charging potential needle is provided, thereby changing the bias in each process. However, such a charging electrometer is expensive, making the electrophotographic apparatus itself expensive. Additionally, some devices are equipped with a switch that changes the contrast depending on the type of document or photo, but such a switch only controls the amount of charge in two levels, and does not necessarily provide optimal control.

Therefore, the main object of the present invention is to provide a photoreceptor for an electrophotographic device, which has a support that can set an optimal potential depending on each process.

(Means for Solving the Problems) Simply put, the present invention provides an electrophotographic apparatus that includes a support having a plurality of electrically partitioned parts that can be set to different potentials at the same time. It is a photoreceptor.

(Effects of the Invention) According to the present invention, different potentials can be set at the same time in each part of the support. The optimum potential can be set according to the process. Therefore, in order to obtain the optimum contrast depending on the type of document, for example, more fine potential control can be easily performed than in the past. Furthermore, there is no need to use expensive charged potential needles.

The above objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

(Embodiment) FIG. 1 is an illustrative diagram showing an embodiment of the present invention. The photosensitive drum 10 includes a hollow cylindrical support 12 and a photoconductive layer 14 formed on the surface thereof.

The support 12, in accordance with the invention, is electrically divided into a plurality of sections so that different potentials can be set simultaneously, as will be explained in detail later.

In the hollow part of the support 12 an insulating roller 15 is arranged in its center, around which a plurality of electrically conductive rollers 16.18.2 are arranged so that they can be rotated by this insulating roller 15.
0, 22, 24, 26 and 28 are arranged. The conductive roller 16 is used for setting the potential of that part of the support 12 during the charging process, and for this purpose it is connected to a charging voltage circuit 30 . The conductive roller 18 is used to detect the current flowing into the support 12 at that portion during exposure, and for this purpose the conductive roller 18 is connected to a voltage extraction circuit 32. Conductive roller 20 is used to set the potential of that portion of support 12 during the development process, and for that purpose conductive roller 20 is connected to a development voltage circuit 34 . 22 conductive rollers, support 12 in the transfer process
It is used to set the potential of that part of the circuit, and is connected to the transfer voltage circuit 36 for that purpose. A conductive roller 24 is used during the separation process to set that part of the support 12 at the optimum potential for separation, and is connected to a separation voltage circuit 38 . moreover,
The conductive roller 26 is used in the cleaning process to bring the parts of the support 12 that it comes into contact with to the optimum potential for cleaning, and for that purpose it is connected to a cleaning voltage circuit 40 .

Finally, conductive roller 28 is connected directly to ground.

A charging corotron 42 connected to a charging high-voltage circuit 43 is disposed near the circumferential side of the photoreceptor drum 10 at a position facing the aforementioned charging voltage setting roller 16, and further downstream in the rotational direction of the photoreceptor drum 10. , a developing voltage setting roller 20. Opposed to the transfer voltage setting roller 22 and the separation voltage setting roller 24, respectively, are developing brushes 33. A transfer corotron 44 and a separation corotron 46 are arranged. The developing brush 33 is connected to a developing bias circuit 35, and the transfer corotron 44 and separating corotron 46 are connected to high voltage circuits 45 and 47, respectively. A cleaning blade 48 is provided opposite the cleaning voltage setting roller 26 and in contact with the circumferential surface of the photoreceptor drum 10 . The static elimination lamp 50 is provided near the circumferential surface of the photoreceptor drum 10 and facing the static elimination voltage setting roller 28 described above.

In such an electrophotographic apparatus, first, the charging corotron 42 is energized by the high voltage circuit 43, and the surface of the photoreceptor 14 of the photoreceptor drum IO is uniformly charged with a predetermined charge.

The photoreceptor 14 is charged by placing a portion of the current generated by corona discharge on the photoreceptor 14 . In this charging process, if static electricity is not removed each time, as shown in FIG. 2, the rise in surface potential becomes gradually slower at the second time compared to the first time, and from the third time compared to the second time, as shown in FIG. This is because the surface potential of the photoreceptor 14 is higher than the case (earth potential) of the charging corotron 42, making it difficult for corona current to reach the photoreceptor 14. For example, length 3
FIG. 3 shows the relationship between the surface potential of a 0 cm selenium drum and the flowing current. Conventionally, in the case of a photoreceptor that is difficult to charge, such as an amorphous silicon drum, the charging time has been increased by increasing the voltage applied to the charging corotron 42 or by widening the case of the corotron 42. However, an increase in the voltage applied to the charging corotron 42 not only generates ozone and nitrides, but also causes deterioration of the photoreceptor and air pollution, and increasing the width of the case is difficult due to space considerations. Undesirable.

In this embodiment, during the charging process, that portion of the support 12 is set to the (-) potential of the charging voltage circuit 30 via the charging voltage setting roller 16. That is,
When charged by the charging corotron 42, that part of the support 12 is set lower than the potential of the charging corotron 420 case, that is, the ground. Therefore,
Applied voltage to charging corotron 42, that is, high voltage circuit 4
3, the surface of the photoreceptor 14 can be efficiently charged, and the voltage circuit 3
By controlling the 0 (-) voltage, it becomes possible to finely adjust the amount of charge.

The photosensitive drum 10, whose surface is positively charged in this manner, is rotated in the direction of the arrow, and then brought to the exposure section. In the exposure section process, a light image from a document is irradiated onto the surface of the photoreceptor 14 of the photoreceptor drum 10 . At this time, in that part of the support 12,
A predetermined resistance 3 is applied through the exposure current extraction roller 18.
Since the resistor 32 is connected to the ground via the resistor 32, an amount of current corresponding to the amount of exposure can be taken out from both ends of the resistor 32. The amount of current is related to the blackness of the developed background, or is proportional to the amount of text (black) in a printer process using reversal development. And the former is the amount of charge to eliminate background fog.

The latter can be effectively used as feedback information for the exposure amount or developing bias, and also as information indicating the amount of toner consumption. That is, by extracting the current during exposure in the exposure process using the current extracting roller 18 in this manner, each of the factors described above can be finely controlled.

The photoreceptor drum 10 is further rotated, and the portion of the support 12 on which the electrostatic latent image was formed during the exposure process is brought to the development station. In this developing process, the developing brush 33
A developer is supplied from the toner, and the (-) charged toner adheres to the electrostatic latent image area. At this time, that portion of the support 12 is connected to the (-) potential of the developing voltage circuit 34 via the developing voltage setting roller 20. Therefore, it is not necessary to apply a developing bias to the developing brush 33 as in the conventional case, and therefore there is no need to insulate the developing brush 33 from the chassis, and the mounting of the developing brush 33 and, in turn, the developing device can be greatly simplified.

The toner image developed in the development process is transferred to the photoreceptor drum 1.
0 is sequentially brought to the transfer section and the separation section in accordance with the rotation of the transfer section 0. In the transfer process, a toner image is transferred by a transfer corotron 44 onto recording paper supplied from a paper feed mechanism (not shown). For example, when transferring (-) charged toner, the recording paper is transferred to (+) by the transfer corotron 44.
) is charged and brought into pressure contact with the photoreceptor drum 10, thereby causing the toner to adhere to the recording paper. However, if there is a gap between the recording paper and the surface of the photoreceptor drum 10, when the toner moves through this gap, it may repel each other due to its own electric charge, resulting in a distorted image. In contrast, in this embodiment, the support 12 in the transfer process is
That part is set to the (-) voltage of the transfer voltage circuit 36 through the transfer voltage setting roller 22. therefore,
In this transfer process, the recording paper is placed on the photoreceptor drum 1.
In addition, the (-) charged toner is more strongly attracted toward the recording paper, so that the transfer efficiency can be increased.

This effect is particularly effective in the case of thick recording paper, recording paper that is difficult to charge due to moisture, or short postcards and business cards that are difficult to apply conveyance force to.

In the separation process, a corotron 4 is separated from the back side of the recording paper.
6 performs AC corona discharge to remove electricity from the paper, weaken the adhesion of the paper to the photoreceptor drum 10 due to static electricity, and separate the recording paper from the photoreceptor drum 10. In this embodiment, that portion of the support 12 in the separation process is connected to a separation voltage circuit 38 via the separation voltage setting roller 24, and that portion of the support 12 in the separation process is connected to the separation voltage circuit 38 via the separation voltage setting roller 24. An AC voltage from the same charge is applied. Then, the photosensitive drum 10 of the recording paper
This not only improves the conveyance of the recording paper and the retention of image quality, but also makes it easier to clean residual toner in the cleaning section afterwards. .

The photosensitive drum 10 is further rotated and brought to the cleaning section. In the cleaning process, the support 12
to that part of the cleaning voltage circuit 40 through the cleaning voltage setting roller 26.
AC voltage is applied. This makes it easier for the toner to separate from the photosensitive drum 10, as shown in FIG. 4, and the burden on the cleaning blade 48 and the like during the cleaning process can be reduced compared to the conventional method.

Finally, in the static elimination process, that part of the support 12 is connected to ground through the conductive roller 28, so that a conventional static neutralization process is carried out.

As in this example, if each part of the support can be set to different potentials at the same time, that part of the support can be set to the optimal potential as each process progresses. It is expected that the efficiency of each process will be increased and the stability of the process will also be improved.

FIGS. 5 to 9 are diagrams showing different embodiments of the present invention, respectively. In the example shown in FIG.
The supporting body 12 of the photosensitive drum 10 is formed by dispersing the particles in the photoreceptor drum 22 and subjecting the particles to surface polishing. Therefore, in this example, each portion of conductive powder 121
22, it is possible to apply or set different individual potentials to that portion.

The embodiment shown in FIG. 5 can also be formed, for example, by impregnating a porous insulator with a conductive material.

In the example of FIG. 6, a conductive wire 123 with a very thin insulation coating is embedded in an insulator 122.

Specifically, such conductive wires 123 are arranged in a cylindrical shape and bonded by heating or the like, and then surface polishing is performed.

Also in this example, each of the conductive wires 123 is connected to the insulator 12
2, a desired potential can be set individually for each part.

In the example shown in FIG. 7, conductive films 125 are formed on the insulating film 124 at intervals, and the photoreceptor 14 is formed thereon so as to cover them. The voltage may be supplied to each conductive film 125 from the side of the photoreceptor 14, as shown in FIG.
It is also possible to make the film 124 slightly conductive and conduct the process from the back side of the film 124.

In the example shown in FIG. 8, electrodes 141 separated from each other are formed on the lower surface of the photoreceptor 14, and the photoreceptor 14
The support member 12 is used as an insulating part between the conductive parts 126 and the insulator 122, and is further reinforced with a mechanically strong support 12 formed of another conductive part 126 and an insulator 122.

In the example shown in FIG. 9, by providing the support 12 with an appropriate resistance value in its surface direction, different potentials can be set individually in each part. In the example shown in FIG. 9, the support 12 of the photoreceptor 14 is thinned so that it acts as a conductor in the thickness direction and as a high resistance layer in the surface direction.
2, it is possible to set partially different potentials.

In the embodiment shown in FIG. 1, the support 1 of the photosensitive drum 10 is
A conductive roller was used to set different potentials on different parts of 2. However, it goes without saying that any other means such as a brush can be used as the potential applying means.

Furthermore, when reducing or copying small originals, toner adhesion can be completely prevented by applying a different potential to the support 12 in the charging and developing processes for areas that should not be formed as images. It can be prevented.

In the above-described embodiments, the photoreceptor is formed into a drum shape. However, it goes without saying that the present invention can also be applied to a photoreceptor formed in the form of a belt or sheet.

[Brief explanation of the drawing]

FIG. 1 is a structural diagram showing an embodiment of the present invention. FIG. 2 is a graph showing a conventional example of changes in surface potential when a photoreceptor is charged three times with the same charging corotron. FIG. 3 is a graph showing a conventional example of the relationship between the surface potential of a photoreceptor and the current flowing therein. FIG. 4 is an illustrative diagram for explaining the state of toner and charges in the cleaning process. FIG. 5 is an illustrative diagram showing one embodiment of the photosensitive drum,
FIG. 5(A) shows its sectional view, and FIG. 5(B) shows its back view. FIG. 6 is an illustrative view showing another example of the photosensitive drum, FIG. 6(A) showing its plan view, and FIG. 6(B) showing its perspective view. FIG. 7 is a diagram showing still another example of the photosensitive drum,
FIG. 7(A) shows a partial perspective view thereof, and FIG. 7(B) shows a partial sectional view thereof. FIG. 8 is a sectional view showing still another example of the photosensitive drum. FIG. 9 is a sectional view showing another example of the photosensitive drum. In the figure, 10 is a photosensitive drum, 12 is a support, and 14
1 is a photoreceptor, 16 to 28 are conductive rollers, 121 is a conductive powder, 122 is an insulator, 123 is a conductive wire, 124 is a film, 125 is a conductive film, 126 is a conductive part, and 141 is an electrode. Patent applicant Sanyo Electric Co., Ltd. Agent Patent attorney Yama 1) Yoshito (and 1 other person) Figure 1 Figure 2 Figure 3 Figure 4 t

Claims (1)

[Claims] 1. A support body having a plurality of electrically partitioned parts that can be set to different potentials at the same time;
Photoreceptor of electrophotographic equipment. 2. A photoreceptor for an electrophotographic apparatus according to claim 1, further comprising means for setting a plurality of portions of the support to different potentials.