JPH0467073A - Contact type charge controller - Google Patents

Abstract

PURPOSE:To accelerate the diffusion and expulsion of a corona discharge forming gas by providing a through-aperture communicating the front and rear sides of a contact member in at least either of the contact member part with a charge carrying member and a contact member supporting part. CONSTITUTION:The through-aperture 1a which communicates the front and rear sides of the contact member 1 is provided in at least either of the contact member part 1 with the charge carrying member 19 or the contact member supporting part 2. The through-aperture 1a functions as a wind flow path communicating and connecting the front and rear sides of the contact member 1 in this way to improve the properties to diffuse and expel the corona discharge forming gas generated near the contact part by the air flow in the machine. Since the diffusion and expulsion are thereby accelerated, the trouble of the stagnating and thickening of the gas is eliminated.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is a method for bringing a voltage-applied or grounded member into contact with the surface of a charge carrier (charged object) such as an insulator, dielectric, or photoconductor. A contact-type charge control device (contact type or direct type charging/static charge removal) that controls (charging or neutralizing) the charge on the surface of the charge carrier by moving the contact member (contact charging member) and the charge carrier relatively. equipment).

(Prior art) For convenience, image forming devices such as electrophotography and electrostatic recording (copying machines, laser beam printers, image display devices, etc.)
For example, in this apparatus, a method for charging or neutralizing the surface of a charge carrier such as an electrophotographic photoreceptor (photoconductor), an electrostatic recording dielectric, a transfer material, a dielectric of an electrostatic adsorption device, etc. Conventionally, a corona discharge device, which is a non-contact charge control device, has been widely used as a device.

FIG. 6 shows a cross-sectional view of an example of the corona discharge device A. 31 is a shield case with a rectangular cross section, 32 is a discharge wire stretched inside this shield case, 33 is a high-voltage power supply for the discharge wire, 34 is a discharge opening, and 35 is a charge carrier facing this discharge opening. 36 is a counter electrode located on the back side of the charge carrier.

The discharge wire 32 is applied by applying high voltage of DC or AC to the discharge wire.
A corona discharge occurs between the shield case 31 and the charge carrier 35, and the surface of the charge carrier 35 facing the discharge opening 34 receives a positive or negative charge, or is charged with a neutral charge. By relatively moving the surfaces of the corona discharge device A and the charge carrier 35, the surface of the charge carrier 35 is sequentially and completely charged or neutralized.

Such a corona discharge device is effective as a device for uniformly charging or neutralizing the surface of a charge carrier to a predetermined polarity and potential.

However, expensive high voltage electricity! (approximately 6 to 8 KV), poor power efficiency, relatively large amounts of undesirable corona discharge gases such as ozone and nitrogen oxides are generated, and discharge wires become dirty or cut. have.

A corona discharge device requires a large amount of current to flow through the shield case in order to stabilize the discharge, and the amount of current used to charge or eliminate static electricity on the charge carrier surface is only a small amount of the current, so that unnecessary discharge occurs. In addition, the amount of corona discharge generated sludge such as ozone increases as the discharge current increases.

The corona discharge generated gas is highly chemically active and causes problems such as a decrease in the charge carrying capacity of the charge carrier and other characteristic deterioration, as well as damage and contamination of the corona discharge device itself.

In contrast to such a corona discharge device, the contact-type charge control device as mentioned above has advantages such as being able to lower the voltage of the power supply, generating only a small amount of corona discharge generated gas such as ozone, and having a simple configuration. Because of this, it has attracted attention as a charging or neutralizing means to replace corona discharge devices, and research is underway to put it into practical use (Japanese Patent Laid-Open No. 57-1782675).
6-104351 ・58-40566 ・58-139
156.58-! 50975, etc.).

For example, by bringing a contact member into contact with the surface of an electrophotographic photoreceptor as a charge carrier and moving it relatively, and applying a voltage of 1 to 2 KV to the contact member, the surface of the photoreceptor may be adjusted to 500 V to 1.5 KV.
This is a process for charging to about KV.

The present applicant has also proposed various improvements for the purpose of uniform charging treatment, etc. For example, DC voltage and oscillating voltage (alternating voltage, pulsating voltage; sine wave, rectangular wave, A contact charging method or device that is based on applying a voltage that is a superimposed voltage such as a triangular wave whose voltage value changes periodically over time (hereinafter referred to as AC voltage or AC voltage component), or on the surface of a charge carrier. A high-resistance layer is provided on the contact member surface in order to prevent charging defects caused by current leakage at surface defects such as holes that may exist (Japanese Patent Laid-Open No. 6
3-149668, 149669, etc.).

FIG. 5 schematically shows a contact type charge control device using a blade type contact member (hereinafter referred to as a charging blade).

10 is a charge carrier. For example, it is an electrophotographic photoreceptor (hereinafter referred to as a photoreceptor drum) in which a photoconductor layer 11 is formed on the outer peripheral surface of a drum-shaped conductive substrate 12 made of aluminum or the like. )
It is rotationally driven with.

1 is a conductive elastic charging plate as a contact member;
It is desirable that the blade has a resistance value of about 105 to 101° Ωcm, and the plate 1 is suitably bent against elasticity with the tip side of the blade approximately parallel to the generatrix of the photosensitive drum 10. It is placed in pressure contact with the surface.

Reference numeral 2 denotes a conductive support member (such as a rigid metal plate) for the blade, which is fixed to a stationary member (not shown). 3 is a power source for applying voltage to the charging blade 1;
By applying a predetermined DC voltage and/or AC voltage to the conductive support member 2, or by grounding the charging plate 1, the surface of the rotating photosensitive drum 10 is brought into contact with a predetermined polarity and potential. is subjected to charging or neutralization treatment.

The contact member 1 may be in any other suitable form, such as a brush type, bat type, rod type, oblong block type, roller type, belt type, web type, etc., in addition to the blade type in the above example.

(Problems to be Solved by the Invention) Although the contact-type charge control device as described above generates a much smaller amount than the corona discharge device, which is a non-contact charge control device, the contact member 1 Air discharge occurs in the microgap near the contact area between the charge carrier 10 and the charge carrier 10, and corona discharge generated gas such as ozone is generated. In the case of a corona discharge device, which is a non-contact charge control device, there is an opposing gap between the device and the charge carrier, and the opposing gap becomes a ventilation path that communicates the front and back of the discharge device, and the corona discharge device The corona discharge generated scum generated in and near the image forming apparatus can be easily diffused and removed relatively smoothly by the air flow inside the machine due to the operation of the internal exhaust/heat exhaust fan of the image forming apparatus or the like.

However, in the case of a contact-type charge control device, there is no gap between the contact member and the charge carrier surface that serves as a ventilation path that communicates the front and rear sides of the contact member, and there is no gap between the contact member and the charge carrier surface, and there is no gap between the contact member and the charge carrier surface. Since the air flow path is mainly limited to the longitudinal direction of the contact member or the width direction of the charge carrier surface, ventilation is difficult to occur in the area near the contact portion between the contact member and the charge carrier.

Therefore, in a contact-type charge control device, even though the amount of corona discharge generated gas such as ozone is small, the generated gas accumulates in the area near the contact area between the contact member and the charge carrier with poor ventilation and over time. As the gas concentration in that area increases, the stagnant and highly concentrated gas acts directly or indirectly on the charge carrier surface and contact members, causing an adverse effect, and in the case of image forming apparatuses, ozone, etc. Output image defects appear due to the influence of corona discharge generated gas.

Therefore, a configuration has been proposed in which a relatively long ventilation path is set up around the contact member to exhaust the air, but this method ensures that the corona discharge generated gas generated in the micro-gaps near the contact part flows reliably without stagnation. If you try to
A new configuration object will be placed in order to set up a fixed ventilation path that will not be interfered with by the movement of the object or the atmosphere, such as temperature. ■ A means to send a fairly strong wind current into the specified ventilation path is required. There were problems such as.

Another idea is to promote gas diffusion by configuring the contact member so that it can move toward and away from the charge carrier surface, and by maintaining the contact member in a position separated from the charge carrier when the device is not in operation. However, this method requires a special mechanism for switching between abutment and separation of the contact members, making the structure complicated and therefore undesirable.

The present invention relates to a contact-type charge control device, which promotes diffusion and elimination of corona discharge generated gas generated near the contact portion between a contact member and a charge carrier by using simpler means and structure, thereby preventing the harmful effects of retention and high concentration. The purpose is to remove.

(Means for Solving the Problems) The present invention involves bringing a voltage-applied or grounded member into contact with the surface of a charge carrier, moving the contact member and the charge carrier relatively, and moving the charge carrier surface. In a contact-type charge control device for controlling electric charge, the front and rear sides of the contact member are attached to at least one of the contact member portion or the support member portion that supports the contact member near the contact portion between the contact member and the charge carrier. A contact type charge control device characterized by having a through opening that communicates with the device.

(Function) That is, by providing the contact member and/or its support member with the front and rear through openings as described above, the through openings can be used in the case of a corona discharge device which is a non-contact charge control device. Similar to the opposing gap between the charge carrier and the charge carrier, it functions as a ventilation path that communicates the front and rear sides of the contact member, and prevents corona discharge generated gas generated near the contact portion between the contact member and the charge carrier. ■Natural diffusivity, ■Diffusivity and exclusion due to airflow caused by relative movement between the contact member and the charge carrier, ■In-machine air flow due to the operation of the internal exhaust/heat exhaust fan of this machine such as the image forming device. Since the diffusibility and elimination properties of the gas are improved and the diffusion and elimination are promoted, it becomes possible to eliminate the harmful effects of retention and high concentration of the gas.

(Example) <Example 1> Fig. 2 is an example of an image forming apparatus (a copy of the Carlson process electrophotographic method) using a contact type charge control device according to the present invention as a primary charging means for a photosensitive drum as a charge carrier. FIG.

During the rotation process, the photosensitive tram 10 is briefly charged to a predetermined polarity and potential by contact with a charging blade l as a contact member to which a voltage is applied. (exposure, laser beam scanning exposure, digital exposure using a light emitting device, etc.)
As a result, an electrostatic latent image corresponding to the target image information is formed, and then the latent image is subjected to regular development or reversal development by the toner developing device 5 and is developed as a toner image.

Next, the toner image on the photosensitive drum surface is sequentially transferred onto the surface of a transfer material P fed from a paper feeding section (not shown) at appropriate timing to a transfer section between the photosensitive drum 10 and the transfer device 6. To go.

The transfer material P passes through the transfer section, is sequentially separated from the surface of the photosensitive drum, and is outputted as an image formation (copy print) through an image fixing device (not shown).

After the image has been transferred, the surface of the photosensitive drum is cleaned by a cleaning device 7 to remove residual contaminants such as untransferred toner, and is then turned over and used for image formation.

In this embodiment, four process devices, a photosensitive drum 10, a charging plated developing device 5, and a cleaning device 7, are collectively configured as a process cartridge 13 that can be attached to and removed from the main body of the image forming apparatus. By using a cartridge, the user does not have to perform troublesome operations such as replenishing toner to the developing device 5 and disposing of toner from the cleaning device 7, and only needs to replace the cartridge with a new one when the cartridge is used up.

When the process cartridge 13 is properly installed in the image forming apparatus main body, the mechanical power transmission system and power supply system between the image forming apparatus main body and the process cartridge 13 are interconnected.

Reference numeral 14 denotes a slit opening for image exposure provided on the upper surface of the outer case of the process cartridge 13. When the cartridge 13 is taken out from the main body of the image forming apparatus, a shutter (not shown) closes the opening 14 and exposes the image. Unnecessary exposure to drum 10 is prevented. Further, the photosensitive drum surface portion exposed to the outside from the bottom side of the cartridge is also hidden by a drum shutter (not shown).

The charging plate 1 is made of conductive elastic rubber made of EPDM, silicone rubber, hydrin rubber, etc. with carbon or metal powder dispersed therein, and is attached to a conductive support member 2 such as a metal plate via a conductive adhesive, and is attached to the tip side. The blade is brought into pressure contact with the surface of the photosensitive drum 10 by the rubber elasticity of the blade.

A voltage is applied to the charging blade 1 via a conductive support member 2 from a power source (not shown) on the image forming apparatus main body side.

As shown in the partially enlarged perspective view of FIG. 1, the charging plate 1 has
A through-thickness opening 1a that communicates the front and rear sides of the charging plate 1 along the plate length is formed near the contact portion with the photosensitive drum 10.

In this embodiment, even if the opening 1a is formed, the charging plate 1
In order to maintain the rigidity (resilience) of the blade, the openings 1a are not continuous and long in the longitudinal direction of the blade, but are arranged intermittently. At this time, the openings 1a are arranged in a staggered manner in order to prevent uneven distribution along the length of the plate with respect to the voltage drop due to resistance in the path from the power supply section side (the conductive adhesive part with the support member 2) to the photosensitive tram 10 in the plate 1. The arrangement was arranged in two rows to smooth out uneven voltage drop distribution along the length of the blade. Further, among the two rows of openings 1a, the opening in the row closer to the contact portion of the blade 1 with the photosensitive drum 10 is enlarged to improve ventilation efficiency near the contact portion.

Since the charged plate 1 is provided with the plate thickness through opening 1a that communicates the front and rear sides of the plate 1 as described above, the electrostatic charge generated in the plate 1 as described in the (effect) section above can be avoided. The ability to diffuse and eliminate corona discharge generated gas from the vicinity of the blade is improved, and the negative effects of retention and high concentration of the dregs are eliminated.

In the case of the image forming apparatus in which the process cartridge is removable in this embodiment, the gas that remains in the space between the front surface of the charging blade 1 and the cleaning device 7 and tends to become highly concentrated is shown by the broken line in FIG. Opening 1 above of blade 1 so that
It is easily pulled out from a to the rear side of the blade, and then exits from the exposure opening 14 of the cartridge outer case to the outside of the cartridge, where it is diffused and eliminated. This flow of diffusion and removal of debris is caused by the steps (1) to (4) described in the (effects) section above.

Conventionally, in order to repeatedly use the photosensitive drum 10, after image transfer, the photosensitive drum surface is cleaned by a cleaning device 7 to remove residual toner, etc., and then the entire surface is cleaned for the purpose of erasing the residual electrostatic latent image (electrical memory). Although a photosensitive drum surface static elimination process using light exposure (eraser lamp) was required, the image forming apparatus of this embodiment utilizes the smoothing effect of the photosensitive drum potential by the alternating voltage component of the voltage applied to the charging plate 1. Since the electrical memory is erased, the entire surface exposure process can be omitted.

This, together with the fact that the charging blade 1 itself occupies a smaller volume than the corona discharge device A, contributes to miniaturization of the entire image forming apparatus.

Further, in the image forming apparatus of this embodiment, which has a removable process cartridge, it is not necessary to provide an opening for full exposure or a shutter in the cartridge outer case, and the structure of the cartridge can be simplified. On the other hand, considering that the opening for full exposure also served as an outlet for the gas produced by corona discharge inside the cartridge outer case, this would impair the diffusion and discharge of the gas, but as mentioned above, By providing the charging blade 1 with the front and rear through openings la, gas can be effectively diffused and discharged.

<Embodiment 2> The opening shape of the front and rear through openings 1a formed in the charging plate 1 is arbitrary. FIG. 3 shows the rigidity of the plate 1 and the uniformity of the voltage distribution in the vicinity of the plate 1, as in Example 1, in which the plate 1 is formed in an elliptical shape with its long diameter direction inclined and intermittently parallel to each other along the length of the plate 1. This was done in consideration of maintaining the

<Embodiment 3> The charging member may have a shape other than a plate type.

FIG. 4 shows a brush body IA made of conductive fibers.

The conductive fibers are implanted in a conductive base fabric IB (power supply member), and are integrally attached and supported by a conductive support member 2 with a conductive adhesive.

A slit-shaped opening 2a is formed in the surface of the support member 2 along the longitudinal direction and passing through the front and rear sides. The opening 2a
can be made as large as possible while maintaining the strength of the support member 2.

The opening 2a formed in the support member 2 allows the
Similar to the opening 1a formed in the charging blade 1 as a contact member as in Examples 1 and 2, the contact member IA
The diffusion and discharge properties of the corona discharge generated gas generated at the contact portion between the photosensitive drum 10 and the photosensitive drum 10 are improved.

The same effect can be obtained even if the opening formed in the contact member and/or its support member has a mesh shape.

(Effects of the Invention) As described above, according to the present invention, the problem of stagnation of corona discharge generated gas generated at the contact portion between the contact member and the charge carrier, which is a problem in contact type charge control devices, can be solved. The adverse effects of high concentration can be solved with a simple means configuration.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a part of the main part of an embodiment of the apparatus. FIG. 2 is a schematic configuration diagram of an example of an image forming apparatus using this apparatus. FIG. 3 and FIG. 4 are front views and perspective views of a part of the main parts of the second and third embodiment devices, respectively. FIG. 5 is a schematic diagram of a contact-type charge control device using a charging plate as a contact member. FIG. 6 is a schematic configuration diagram of an example of a corona discharge device. 1. IA is a charging plate or brush body as a contact member, 2 is its support member, 1a and 2a are front and rear through openings for ventilation formed in the contact member or its support member, 1
0 is an electrophotographic photosensitive drum as a charge carrier. Patent applicant Canon Co., Ltd.a a

Claims (1)

[Claims] (1) In a contact-type charge control device that controls the charge on the charge carrier surface by bringing a voltage-applied or grounded member into contact with the charge carrier surface and moving the contact member and the charge carrier relatively. , at least one of the contact member portion or the support member portion supporting the contact member near the contact portion between the contact member and the charge carrier is provided with a through opening that communicates the front and rear sides of the contact member. A contact type charge control device featuring: