JPH0529909B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention includes at least an electrophotographic photoreceptor;
The present invention relates to an electrophotographic process cartridge that can be attached to and replaced with an electrophotographic apparatus main body.

An example of an electrophotographic apparatus using the above cartridge will be explained with reference to FIG.

FIG. 1 shows a sectional view of the main body C of the electrophotographic apparatus. In the figure, reference numeral 1 denotes a document mounting table made of a transparent member such as glass, which reciprocates on a rail R in the direction of arrow a. 2 is a small-diameter imaging element array such as a focusing light transmitter (product name: SELFOC) or a bar lens, and the document O placed on the document table 1 is illuminated by an illumination lamp L, and its reflected light is The image is slit-exposed onto an electrophotographic photosensitive drum 3 rotated in the direction of the arrow by the array 2 through an opening 15 and a filter 16 provided in a cartridge 14. Also 4
is a charge for sensitizing the photoreceptor, which applies a corona discharge to the drum 3 and gives the photoreceptor a charge that is dissipated in the area irradiated with the image light during image exposure. For example, the zinc oxide photosensitive layer Alternatively, the photosensitive drum 3 coated with an organic semiconductor photosensitive layer or the like is uniformly charged. The drum 3, which is uniformly charged by the photosensitive charger 4, is subjected to image exposure by the element array 2 to form an electrostatic image. This electrostatic latent image is then developed into a developed image by a developing device 5. On the other hand, the sheet P on the stacking table S is fed onto the drum 3 by a feed roller 6 and a registration roller 7 that rotates in synchronization with the image on the photosensitive drum 3. Then, the toner image on the photosensitive drum 3 is transferred onto the sheet P by the transfer charger 8. Thereafter, the sheet P separated from the drum 3 by the separating means 9a is guided to the fixing device 10 by the guide 9, and after the toner image on the sheet P is fixed, the sheet P is discharged onto the tray 12 by the discharge roller 11. be done. On the other hand, the toner remaining on the drum surface after transfer is cleaned by the cleaning device 13, and the above image forming process is repeated.

The electrophotographic process cartridge described above includes a drum 3, a charger 4, a developing device 5, and a cleaning device 13 inside a frame 14a. As shown in FIG. 2, this cartridge 14 is provided so that it can be inserted into and removed from the main body C of the electrophotographic apparatus, that is, it can be freely attached and detached. The sliding portion 14b of the frame 14a of the tray 14 is engaged and guided. Also, D is the front door of the main body C.
In FIG. 2, the lower side is connected to the main body C with a hinge.

Therefore, the cartridge 14 attached to the main body C
The cartridge 14 is replaced with a new cartridge 14 based on the lifespan of the photoreceptor.

In the above, in addition to the photoreceptor, the cartridge 14 includes a photosensitive charger 4, a developing device 5, and a cleaning device 1.
3, but a transfer charger 8 may also be built in, or conversely, a photosensitive charger 4, and/or a developer 5, and/or a transfer charger 8, and/or a cleaning device 13. may be attached to the main body instead of being built into the cartridge 14. In any case, only the photoreceptor is built into the cartridge to facilitate its replacement.

Generally, the charging ability of photoreceptors varies depending on the manufacturing environment and from one production lot to another. If the charging ability of the photoreceptor varies, a predetermined latent image potential cannot be obtained under certain charging conditions, and the dark area potential becomes too high or too low. Therefore, it is preferable to adjust the charging conditions according to the charging ability of the photoreceptor, but in the case of the above-mentioned process cartridges, it is not possible for the user to adjust the adjustment means on the main body side depending on the cartridge. This is inconvenient because it places a burden on the user and makes it easy for the user to forget to make adjustments.

The present invention aims to solve the various disadvantages mentioned above.

Embodiments of the present invention will be described below with reference to the drawings.

In the embodiment of FIGS. 3, 4 and 5, the cartridge 14
A photosensitive charger 4 is built in together with a photoreceptor 3, and a high voltage is applied to the charger 4.
It has a linear electrode 17 for performing corona discharge, a shield member 18 surrounding a part of the periphery of this electrode 17, and, in FIGS. 3 and 4, a grid 19.
The cartridge 14 has a built-in adjustment means 20 for adjusting the charging potential of the photoreceptor. In the illustrated example, the means 20 connects a constant voltage element (varistor, Zener diode, etc.) 21 and a variable resistor 22 in series, and the variable resistor 22 side is grounded. Further, the cartridge 14 is provided with a contact 24 connected to the electrode 17, and when the cartridge 14 is inserted into a predetermined position in the main body C and loaded, the contact 24 is connected to the electrode 17.
4 is connected to a contact 25 provided on the main body C side.
This contact 25 is connected to the high voltage power supply 2 provided on the main body C side.
3, when the contacts 24 and 25 are connected, a high voltage can be applied to the electrode 17.

In FIG. 3, the shield member 18 is electrically grounded and the adjusting means 20 is connected to the grid 19. In FIG. 4, the adjusting means 20 is connected to the shield member 18 and the grid 19, and in FIG. Adjustment means 20 are connected to member 18 .

The operation shown in FIG. 3 will be explained first.

When the cartridge 14 is first set in the copying apparatus main body C and the copy switch is turned on to start copying, the high voltage power supply 23 is activated and the electrode 1 of the charger 4 is activated.
7 starts corona discharge. A part of the corona current generated by corona discharge is transferred to the shield member 1 of the charger.
8, a portion flows to the grid 19, and a portion flows to the photoreceptor 3. The corona current flowing through the grid 19 is applied to the constant voltage element 21 to maintain the grid 19 at a certain potential.

On the other hand, it is known that the potential of the photosensitive member depends on the grid potential of the charger. For example, the 9th
As shown in the figure, when the horizontal axis is the grid voltage and the vertical axis is the surface potential of the photoreceptor, the grid voltage and the surface potential are almost proportional and do not depend much on the current value 1 flowing to the electrode 17. It is also known that the grid has a great effect of making the surface potential of the photosensitive member uniform, and that the change in the corona current value due to environmental changes can be made relatively small.

The grid 19 of the charger 4 has a plurality of (for example, 5) tungsten or stainless steel wires stretched at regular intervals (for example, every 2 mm), and a part of the grid 19 on the upstream side in the rotational direction of the drum is wired. The grid is not stretched. By doing so, the charging efficiency of the primary charger can be increased without reducing the effect of the grid on keeping the potential constant. (This also applies to the following embodiments.) In the above, by adjusting the resistance value of the variable resistor 22 according to the charging ability of the photoreceptor 3 and adjusting the voltage generated by the means 20, Even if it is a power source that flows a constant current to the electrode 17 of any cartridge, the surface potential of the photoreceptor after being charged by the charger 4 can be kept constant even if the photoreceptor charging ability varies depending on the cartridge. Therefore, the above adjustment can be carried out at a factory or the like when assembling the cartridge, without bothering the user.

In addition, the high voltage power supply 23 in the above case uses a constant current transformer, which stabilizes the current flowing through the grid and keeps the voltage generated in the grid almost constant.
Therefore, the surface potential of the photoreceptor is kept approximately constant. When a constant current transformer is used in this manner, the surface potential of the photoreceptor becomes more stable against changes in the environment such as humidity and temperature. However, even with a constant voltage transformer, the grid is maintained at a substantially constant potential due to the constant voltage characteristics of the voltage generating member connected to the grid, so this does not contradict the gist of the present invention. (The same applies to the following embodiments.) The grid 19 of the charger 4 and the shield member 18 may be connected as shown in FIG. 4 and maintained at the same potential. In this way, the voltage applied to the shield member 18 increases the current flowing in the direction of the photoreceptor, increasing the charging efficiency of the charger 4, and making it possible to obtain a high surface potential with a small primary current. .

As shown in FIG. 5, a method may be used in which the bias voltage applied to the shield member 18 of the charger 4 is changed by the adjusting means 20 depending on the photoreceptor in the cartridge.

This method is effective as a simple method if the potential on the photoreceptor can be maintained relatively uniformly.

Particularly in the case of charging by AC corona discharge, the effect of controlling the photoreceptor potential by changing the voltage applied to the shield member is large and effective.

FIG. 6 shows that the cartridge 14 is connected to the photosensitive drum 3,
It incorporates a grid 19 and a grid voltage generating means (adjusting means) 20 in which a varistor 21 and a variable resistor 22 are connected in series.

The electrode 17 and shield member 18 of the charger 4 are attached to the main body C side of the copying apparatus, and when the cartridge 14 is pushed into the main body C of the apparatus, the grid 19 faces the electrode 17 through the opening of the shield member 18. It will be placed in a position where
The discharger 4 is now completed. Although the shield member 18 is electrically grounded in this figure, it may be connected to the voltage generating means 20. In this case, a contact connected to the means 20 is provided on the cartridge 14 side, and a contact connected to the shield member is provided on the main body C side, and the cartridge 1
4 is inserted into the main body C and set, both contacts are joined and the means 20 and the shield member 18 are connected.

In FIG. 7, a cartridge 14 houses a photoreceptor 3 and voltage generating means (adjusting means) 20 in which a varistor 21 and a variable resistor 22 are connected in series.

The charger 4 (electrode 17, shield member 18, grid 19) is attached to the main body C. 26
is a contact connected to the means 20; 27 is a contact connected to the shield member 18 and the grid 19;
The contact 26 is provided on the cartridge 14, and the contact 27 is provided on the main body C side. When the cartridge 14 is inserted into a predetermined position in the main body C and set, both contacts 26 and 27 are connected, and the means 20, the shield member 18, and the grid are connected. 19 are connected.

Grid 19 may be eliminated in FIG. 7, or shield member 18 may be electrically grounded.

As described above, it is preferable that the adjusting means (voltage generating means) is a combination of a constant voltage element (varistor, Zener diode, etc.) and a variable resistor. In other words, it is desirable that the adjusting means have both the function of generating a constant voltage as described above and the function of adjusting this voltage. Furthermore, it is known that the voltage generated by constant voltage elements such as Zener diodes and varistors varies by a maximum of ±5% depending on the production lot, and it is also necessary to correct this variation.

Therefore, by using a constant voltage element to generate a voltage that is approximately 90% of the voltage applied to the shield member or grid, and by making the remaining 10% or so generated by a variable resistor and making it adjustable, the voltage generation member can be adjusted. It can satisfy two functions: constant voltage property and voltage adjustment. That is, as shown in Fig. 10, A is the variation of the photoconductor converted into grid voltage, B is the variation of the constant voltage element, and the range of B is the range A of the variation of the photoconductor. Avoid this.

Therefore, the adjustment range of the variable resistor is part C, which is the sum of A and B, and the resistance value of the variable resistor is selected so that a voltage within this range can be generated. For example, the fourth
In the cartridge configured as shown in the figure, when -500 .mu.A of current flows to the electrode 17, about -490 .mu.A flows to the voltage generating means 20. Therefore, a varistor with a rating of -600V was used as a constant voltage element, and the maximum
By using a 400KΩ variable resistor, it is possible to correct variations in the photoreceptor and varistor.

Furthermore, as shown in FIG. 8, the constant voltage element 20 may be provided on the main body C side, and a variable resistor 22 may be provided in the cartridge 14 to set the resistance value in accordance with the electrical characteristics of the photoreceptor 3. . In the figure, 28 is a contact connected to the variable resistor, 30 is a contact connected to the grid 19, and is provided on the cartridge 14, respectively.On the other hand, 29 and 31 are contacts connected to the constant voltage element 21 on the main body C side. It is set in. When the cartridge 14 is inserted into the main body C at a predetermined position and set, the contacts 28 and 30 are connected to the contacts 2, respectively.
9, 31, and grid 19 is connected to constant voltage element 2.
1, connected to variable resistor 22;

The method shown in FIG. 8 can also be applied to the methods shown in FIGS. 4 to 7.

By connecting the illustrated constant voltage element to the high voltage side and the variable resistor to the low voltage side, a small variable resistor with low insulation resistance can be used as the variable resistor. Of course, the variable resistor may be placed on the high voltage side and the constant voltage element may be placed on the low voltage side (ground side).

Further, although a variable resistor is used in the above example, a fixed resistor having a resistance value corresponding to characteristics such as the charging ability of the photoreceptor may be selected for each cartridge and used in the cartridge.

Alternatively, the resistor may be omitted and a constant voltage element having voltage characteristics corresponding to the characteristics of the photoreceptor may be selected for each cartridge and used in the cartridge.

Further, in addition to the above configuration, a developing device, a cleaner, a pre-exposure means, etc. may be added to the cartridges shown in FIGS. 3 to 7.

According to the present invention, since the charging potential is made constant for each electrophotographic process cartridge in accordance with the characteristics of the photoreceptor, it is possible to obtain equally good images no matter which cartridge is used. It is possible.

The present invention can also be applied to electrophotography in which images are recorded using laser beams or LED light modulated in accordance with recorded signals from computers, word processors, facsimile transmitters, etc.

[Brief explanation of the drawing]

1 and 2 are explanatory diagrams of an example of an electrophotographic apparatus to which the present invention can be applied, FIGS. 3 to 8 are explanatory diagrams of an embodiment of the present invention, and FIG. 9 is an explanatory diagram of a grid effect.
FIG. 10 is an explanatory diagram of the adjustment range. 3 is an electrophotographic photosensitive drum, 4 is a charger, 17
is an electrode, 18 is a shield member, 19 is a grid,
21 is a constant voltage element, and 22 is a variable resistor.

Claims (1)

[Scope of Claims] 1. An electrophotographic process cartridge that includes at least an electrophotoreceptor and is removably attachable to the main body of an electrophotographic apparatus, wherein the photoreceptor is connected to a charging means that charges the photoreceptor, and the photoreceptor is exposed to light according to the characteristics of the photoreceptor. 1. An electrophotographic process cartridge, comprising an adjusting means capable of adjusting the charged potential of the body, the adjusting means comprising a variable resistance element. 2. The process cartridge comprises at least one of a charging means, a developing means, and a cleaning means for the photoreceptor.
The electrophotographic process cartridge described in Section 1. 3. An electrophotographic apparatus having at least a built-in electrophotographic photoreceptor and having a removable electrophotographic process cartridge, which has a power source for supplying power to a charging means for charging the photoreceptor, and the process cartridge is connected to the charging means. An electrophotographic apparatus characterized in that it has an adjusting means that is connected to the photoreceptor and can adjust the charging potential of the photoreceptor according to the characteristics of the photoreceptor, and the adjusting means includes a variable resistance element. 4. The process cartridge is provided with at least one of a charging means, a developing means, and a cleaning means for the photoreceptor.
The electrophotographic device described in Section 1.