JPS61275777A - Ozone removing device for electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To dissolve produced ozone and to prevent the ozone from exerting adverse influence upon a photosensitive body and environment by adding an ultraviolet-ray source in or nearby a separation charger. CONSTITUTION:The ultraviolet-ray source 12 is fixed by a fixing member 22 to corner parts of the side wall part 19 and belt tip part 21 of the shield case 13 of an AC corona charger 9 which separates transfer paper carrying a toner image from a drum. Then, the light source 12 is put opposite the corona wire 14 of the charger 9 so that the light source 12 and a photosensitive layer are shielded by the tip part 21. Consequently, produced ozone is dissolved effectively and the photosensitive layer is prevented from being exposed to ultraviolet rays directly.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an ozone removal device for an electrophotographic copying machine, and more particularly to an ozone removal device that utilizes photodecomposition of ozone.

(Prior Art and Technical Problems of the Invention) In a commercial electrophotographic copying method, an electrophotographic photoreceptor drum is charged to a certain polarity and an electrostatic image formed by imagewise exposure is developed. After forming a toner image, a transfer paper is brought into contact with this drum, and then a corona discharge of the same polarity as the electrostatic image is generated from the back side of the transfer paper to transfer the toner image onto the transfer paper. Following this electrostatic transfer, the transfer paper is electrostatically attracted to the drum surface, so an operation is performed to separate the transfer paper from the drum.

All of the above-mentioned charging and neutralizing operations in electrophotographic copying machines are performed by corona discharge from a corona discharger, but during this corona discharge, ozone is generated.
There is a problem that this ozone deteriorates the surface of the photosensitive layer. The amount of ozone generated is significantly lower in negative polarity corona discharge than in positive polarity corona discharge. Therefore, an electrophotographic photoreceptor having a positively charged photosensitive layer is used, and It is widely used to perform main charging and toner transfer charging using positive corona discharge. However, even in this case, problems still arise when separating the transfer paper. That is, mechanical separation methods such as claw separation and belt separation, and techniques such as AC corona static elimination separation are used to separate the transfer paper.

The former mechanical separation method may distort the transfer of the toner image or cause disturbances in the toner image on the transfer paper, so AC corona static elimination separation is now widely used. It has reached this point.

Ozone is also inevitably generated during this AC corona static elimination process.1 The generated ozone creates an ozone flow together with the airflow inside the machine caused by the rotation of the photoreceptor drum, and this ozone flow causes significant deterioration of the photoreceptor layer. be affected by negative effects such as In particular, in amorphous silicon photoreceptors with excellent sensitivity and selenium-arsenic photoreceptors with excellent printing durability and surface hardness, the ozone flow causes fatal defects in images formed.

In order to prevent this, various measures have been taken, such as blowing air through the corona discharger to cause the ozone flow to escape from the drum surface, and various other measures have been taken, but the influence of the ozone flow on the drum surface has not yet been completely eliminated. I haven't reached the point where I can. Furthermore, since the ozone produced is an air pollutant, discharging it directly outside the aircraft poses a problem in terms of environmental hygiene.

(Object of the Invention and Outline of the Invention) Therefore, an object of the present invention is to provide an electrophotographic copying machine that effectively decomposes ozone generated within the electrophotographic copying machine on the spot and prevents the adverse effects of ozone on the photosensitive layer and the environment. is to provide.

Another object of the present invention is to provide an apparatus for effectively photodecomposing ozone generated during AC corona static elimination without adversely affecting the photosensitive layer or inhibiting copying operations.

The present inventor has discovered that by irradiating the AC corona static elimination area or its vicinity with ultraviolet rays of a certain wavelength, ozone generated can be effectively decomposed and removed into a harmless form without adversely affecting the photosensitive layer. I found out.

(Structure of the Invention) According to the present invention, there is provided an electrophotographic photosensitive drum having photoconductivity, a main charger for uniformly positively charging the surface of the drum, and a main charger for exposing the charged drum surface to an image. An optical system, a developing mechanism for developing the formed electrostatic image with toner, and a toner 1 - charge with the same polarity as the electrostatic image from the back side of the transfer paper with the transfer paper overlaid on the drum surface having the image. In an electrophotographic copying machine consisting of a transfer charger for performing alternating current charge removal from the back side of the transfer paper and a separation charger for separating the transfer paper from the drum surface, in or near the separation charger.

There is provided an ozone removal device characterized in that it is equipped with an ultraviolet light source that emits ultraviolet light with a wavelength of 200 to 400 nm.

(Preferred Embodiments of the Invention) The present invention will be described in detail below based on specific examples shown in the accompanying drawings.

Apparatus Overview In FIG. 1 showing an example of an electrophotographic apparatus to which the ozone removal apparatus of the present invention is suitably applied, the surface of a photoreceptor drum 1 is coated with a positively chargeable electrophotographic photosensitive material such as 5S-All. Layer 2 is provided. Around this drum 1,
A corona charger 3 for uniformly charging the surface of the photosensitive layer (for example, positive charging), an optical system 4 for imagewise exposing the charged photosensitive layer, and developing with toner the electrostatic image formed by the charging exposure. A developing mechanism 5 is provided for this purpose. In order to transfer the toner image on the surface of the photosensitive drum onto the transfer paper 6, a transfer paper supply mechanism 7 is provided to feed the transfer paper 6 into contact with the drum surface. is provided with a corona charger 8 (having the same polarity as the corona charger 3) for toner transfer and an AC corona charger 9 for separating the transfer paper carrying the toner image from the drum. On the opposite side of the photosensitive drum IK from the transfer paper supply mechanism 7, a transfer paper conveyance mechanism lO such as an endless belt is provided, and this conveyance belt)
The IOK may be provided with a suction mechanism 11 for holding the transferred transfer paper on the belt 10.

According to the present invention, by providing the ultraviolet light source 12 that emits ultraviolet light with a wavelength of 200 to 400 nm inside or near the separating corona charger 9, the photosensitive layer 2 can be prevented from being adversely affected at all. , which effectively decomposes and removes ozone generated by AC corona discharge on the spot.

Principles and Effects of the Invention Ultraviolet rays are classified into three types according to their wavelength: vacuum ultraviolet rays, ultraviolet rays, and near ultraviolet rays, but those involved in ozone decomposition are within the wavelength range of 200 to 400 nm. Ultraviolet rays and near-ultraviolet rays are the only ones, but vacuum ultraviolet rays are more involved in ozone production.

FIG. 2 of the accompanying drawings shows a low-pressure mercury discharge tube scuttle suitably used as the ultraviolet light source 12 in the present invention, and it can be seen that this light source has a strongest line at a wavelength of 253.7 nm.

On the other hand, FIG. 3 shows the spectral sensitivity curve of the S@-As photosensitive layer (As2Ss), and this photosensitive layer has the above-mentioned wavelength of 200
It can be seen that for light rays between 400 nm and 400 nm, and especially 253.7 nm, there is little to no II&degree.

The photodecomposition reaction of ozone is expressed by the following formula.

hν 0 0+0□ ...(1) 0+0
,20□ ・-(2) Above (1) and (2)
) is said to have a quantum yield of 4 to 6.

Furthermore, if NO□ and H2O are present in the atmosphere, the decomposition of 03 is promoted by the catalytic reaction described below.

NO+O--→NO+02...(3)No
-) -0--→NO□+02 ... (4) hν NQ -1 → NO+0 ... (5) This catalytic reaction will proceed sufficiently if 109 or more NO□ exist in 1 ec of the atmosphere. It is said that N in the atmosphere
Since there are about 1014 O2 atoms/F3, it is recognized that this catalytic reaction proceeds and the decomposition of 0377) reaches about twice that in the case of formulas (1) and (2).

Thus, it is clear that according to the present invention, ozone generated during alternating current corona discharge can be effectively decomposed and removed on the spot without adversely affecting the photosensitive layer 2 due to pre-exposure.

Specific Examples of Apparatus As the ultraviolet light source, the above-mentioned low-pressure mercury lamp is most advantageously used, but other light sources such as a combination of a high-pressure mercury lamp with an ultraviolet-transmitting and visible-absorbing filter may also be used. The output of the ultraviolet light source depends on the output of the AC corona discharger, etc., but generally it is within the range of 400 to 10,000 pW/an 1, especially 2,000 to 5,000 μW/6n2,
Ozone can be effectively decomposed while preventing the adverse effects of ozone on the photoreceptor.

In FIG. 4, which shows one preferred embodiment of providing the ultraviolet light source 12, the ultraviolet light source 12 is provided within the AC corona charger 9 and integrally therewith. This separation charger consists of a shield case 13 and a corona wire 14 disposed within the shield case. Electrically insulating supports 15m and 15b are provided at both ends of the shield case 13, and one 15m is provided with a connection member 16 to a power source such as a plug.
However, a tension member 17 such as a coil spring is provided on the other side, and the corona wire 14 is installed under constant tension between these members.

The shield case 13 has a side wall portion 1 on the side where the photoreceptor drum is introduced.
8, a side wall portion 19 on the photosensitive drum delivery side, and a bottom wall portion 20 that connects these opposite side wall portions. The tip 21 of the side wall portion 19 on the photosensitive drum delivery side is directed inward by approximately 90 mm.
The low-pressure mercury lamp 12 is fixed to a part of the corner between the side wall part 19 and the bent tip part 21 by a suitable fixing member 22. A connection member 23 for the low-pressure mercury lamp 12 is provided on the insulating support 15m described above.

According to this aspect of the present invention, the ultraviolet light source 12 is provided so as to face the corona wire 14, and furthermore, the ultraviolet light source 12 and the photosensitive layer 2 are separated by the bent end portion 21 of the shield case. This has the advantage that the generated ozone is most effectively decomposed, and the effects of direct exposure of the photosensitive layer 2 to ultraviolet rays are also prevented.

The present invention relates to a device that can effectively remove ozone generated by alternating current corona discharge near a separation charger.Recently, there has been a trend to use organic photoreceptor drums in small-sized or low-speed copying machines. . Generally, organic photoreceptors are often used with negative chargeability, and in this case, the main charger and transfer charger perform negative corona discharge, resulting in significant ozone generation. By attaching the ozone removal device of the present invention to the main charger and the transfer charger, it is possible to obtain the effect that even when a negative corona discharge is applied to a photosensitive layer such as an organic photoreceptor, there is no adverse effect on the image obtained.

[Brief explanation of the drawing]

FIG. 1 is an explanatory view of the main parts of an electrophotographic apparatus to which the ozone removal apparatus of the present invention is suitably applied. FIG. 2 is a diagram showing the spectrum of the low-pressure mercury discharge tube used in the present invention. FIG. 3 is a diagram showing the spectral sensitivity of the 5s-A6 photosensitive layer (A112S03). FIG. 4 is a perspective view showing a specific usage example of the ozone removal device of the present invention. l...Photosensitive drum, 3...Main charger, 8
...Transfer charger, 9.-Separation charger, 12.
...Ultraviolet light source. Patent applicant: Mita Kogyo Co., Ltd. Representative Patent Attorney Ikuo Suzuki Figure 2 Figure 3 Jl Hisashi (nm)

Claims (1)

[Claims] (1) An electrophotographic photosensitive drum having photoconductivity, a main charger for uniformly charging the surface of the drum, an optical system for imagewise exposing the drum surface after charging, and a static image formed on the drum surface. A developing mechanism for developing an electrostatic image with toner, a transfer charger that charges the transfer paper with the same polarity as the electrostatic image from the back side of the transfer paper while the transfer paper is stacked on the drum surface with the toner image, and an AC In an electrophotographic copying machine comprising a separation charger for removing static electricity and separating the transfer paper from the drum surface, an ultraviolet light source that emits ultraviolet light with a wavelength of 200 to 400 nm is attached in or near the separation charger. An ozone removal device characterized by: