JPS5930562A - Lighting device of electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To prevent the decrease in reflectivity with high eficiency as a magnetic toner is attracted onto a magnetic member by a magnetic attraction action, by providing the magnetic member to the part, which does not contribute to condensing of light, of a reflecting mirror which condenses the light from a light source like a slit to an illumination part for an original. CONSTITUTION:Reflecting mirrors 2A, 2B differ in eccentricity each other. The focuses on one side of the upper half part 2A and lower half part 2B thereof are made coincident and the filament 1A of a light source lamp 1 is disposed in such focal position. The respective other focuses are positioned near an illumination part 10 for an original. The direct light by the light source 1 and the reflected light by the mirror 2 are condensed at a specified width in the part 10 positioned diagonally above the mirror 2. The reflected light L2 thereof advances to a photoreceptor drum side without receiving the interference of the mirror 2. A magnet M is embedded in the part where the reflected light is shielded by the lamp 1 and which does not effectively contritube to the condensing along the longitudinal direction of the mirror 2. As a result, the sticking and depositing of the toner on the effective reflection surface are obviated and the decrease in the reflectivity of the reflecting mirror is prevented.

Description

[Detailed Description of the Invention] The present invention provides a magnetic toner? This invention relates to an illumination device used in a slit exposure type copying machine.

In a copying method using an electrophotographic process, first, in a dark place, a uniform charge is applied to the surface of a photoreceptor having a photoconductive insulating film attached to a conductive support. This charge is normally provided by corona discharge. Next, the original image to be copied is projected onto the surface of the photoreceptor through a lens system,
Form an electrostatic image.

Although there are various methods for developing this electrostatic image, the cascade development method is often used. According to this method, toner particles are attached to the surface of carrier beads by triboelectric charging.
A so-called two-component developer is used, and the developer is cascaded onto the surface of the photoreceptor.

Meanwhile - the electrostatic forces of the original image overcome the bonding forces between the carrier and toner and the toner adheres to the original image area.

In a normal electrophotographic process, the thus obtained toner image is transferred to paper and then heated and fixed.

By the way, in the above-mentioned two-component developing method, since the distribution ratio of toner and carrier is important, a mixing mechanism is required, and as the device becomes larger, there is a problem that the carrier that is repeatedly used gradually deteriorates. be.

In response, a -component type developing method has been proposed and is attracting attention as a maintenance-free, low-cost, small-space developing machine.

As an example, U.S. Pat. No. 3,909,258 (
There is an induced charge type development method described in Cl 96/I R). In this method, as shown in FIGS. 1 and 2, conductive toner T containing magnetic powder is supplied between a rotating body 01 including a magnet 02 and a photoreceptor 03. When the conductive toner T comes into contact with the latent image area (positively charged in the figure), an electric charge is generated on the rotating body 01 by electrostatic induction (→The electric charge is transmitted through the toner T, and the toner 2. T
is attracted by the latent image charge, overcomes the magnetic attraction force of the magnet)02, and development is performed.

The present invention improves the illumination device in a copying machine using such magnetic toner.

FIG. 3 schematically shows a slit exposure type copying machine using a reflecting mirror. Light from a light source lamp 1 is reflected by a reflecting mirror 2 and focused in a slit shape onto a document surface on a platen glass 3. The original 4 is moved by moving the platen glass 3 and
During the movement, the slit-shaped irradiation light is scanned, and the reflected light is exposed onto the photoreceptor drum 6 by the exposure lens 5. The electrostatic latent image formed on the photoreceptor drum 6 by exposure is developed by a developing device 7, and the resulting toner image is transferred onto the paper P using discharge from the transfer corotron 8.

However, in such a type of copying machine, toner scattered from the developing device 7 or the cleaning unit 9 floats inside the machine, adheres to and accumulates on the reflecting surface of the reflecting mirror 20, and tends to reduce the reflectance of the reflecting mirror 2. .

Therefore, there is a problem in that the amount of light required for exposure is insufficient or uneven illuminance occurs, which adversely affects the quality of the copied image.

The present invention was obtained by addressing such problems,
Magnetic toner? In the slit exposure type copying machine used,
A magnetic member is attached to a portion of the reflecting mirror that focuses light from the light source into the original illumination section in a helical shape, but does not contribute to light focusing.

It is an object of the present invention to improve the reliability of an illumination device in a slit exposure type copying machine that uses magnetic toner, thereby obtaining high-quality copied images.

Embodiment 2 of the present invention will be described below with reference to FIGS. 4 to 6.

This embodiment is applied to an electrophotographic copying machine of the type shown in FIG. 3, and the main structure thereof will be explained.

The reflecting mirror 2 is an ellipsoidal mirror, and is fixedly arranged parallel to the platen glass 3 across the document width direction. Moreover, the upper half 2A and the lower half i2B of the reflecting mirror 2 have different eccentricities from each other, and are shaped like three ellipsoidal mirrors put together. match,
The filament IA of the light source lamp 1 is arranged at the parfocal position, and the other focal point of each is located near the document illumination section 10.

Therefore, the direct light from the light source lamp 1 and the reflecting mirror 2
The reflected light L1 from the original 4 is focused at the document illumination unit 10 located diagonally above the reflecting mirror 2 to form a width t, and the reflected light L2 from the original 4 is obstructed by the reflecting mirror 2. The light travels toward the photoreceptor drum 6 side without any interference.

In addition, there is a part at the deepest part of the reflecting mirror 2 where the reflected light is blocked by the light source lamp 1 and does not effectively contribute to irradiation of the document.
A magnet M is attached to the rotating portion in the longitudinal direction of the reflecting mirror 2.
is buried. The upper surface of this magnet (M) has single polarity.

The magnetic toner T floating in the copying machine and entering the reflecting mirror 2 is attracted by the magnetic action of the magnet M and adheres to the rotating portion (see FIG. 6). Therefore, the magnetic toner T does not adhere or accumulate on the reflective surface of the reflective mirror 2 that effectively contributes to document illumination.

The present invention is not only applied to the movable platen glass copying machine as shown in the above embodiment, but also to a copying machine comprising a light source lamp 1 and a reflecting mirror 2, as shown in FIGS. 7 and 8. Needless to say, the present invention can also be applied to a stationary platen type copying machine in which original scanning is performed by using an illumination device such as that shown in FIG.

Further, the reflecting mirror is not limited to an ellipsoidal mirror, and may have other shapes.

As is clear from the description of the embodiments above, in the present invention,
In slit exposure copying machines that use magnetic toner,
Magnetic N5 strips are attached to the parts of the reflector that do not contribute to light condensation of the reflector that focuses the light source light onto the document illumination section in a slit shape. Toner is attracted to the magnetic member by magnetic attraction. Therefore, magnetic toner does not adhere or accumulate on the effective reflection surface of the condensing reflector, effectively preventing a decrease in the reflectance of the reflector, and improving the reliability of the lighting device over a long period of time. can be maintained.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a developing section of a known electrophotographic process using magnetic toner, FIG. 2 is an enlarged conceptual diagram of the same main part, and FIG. 3 is an explanatory diagram showing a developing section of a known electrophotographic process using magnetic toner. A schematic diagram of a photocopying machine, FIG. 4 is a longitudinal cross-sectional side view of the illumination device according to the above embodiment, FIG. 5 is a perspective view of a reflecting mirror in the illumination device, and FIG. 6 is a magnetic toner using the reflecting mirror. An enlarged view of the main parts showing the suction state, and FIGS. 7 and 8 are schematic explanatory views of other types of electrophotographic copying machines to which the present invention can be applied. 1...Light source lamp, IA...Filament, 2...
・Reflector lens, 6... Photosensitive drum, 7... Developing device,
8... Transfer corotron, 9... Cleaning unit, 1o... Original illumination unit, 11.12.13... Mirror. Agent Patent Attorney Ehara Wang Gai 1 person Fan 1 Figure 2 Figure 3 Figure 4 Figure F3 Fan 5 Figure Fan 6 Figure 7 Figure 8

Claims (1)

[Claims] In slit exposure copying machines that use magnetic toner,
comprising an exposure light source and a reflecting mirror attached to the exposure light source and condensing a part of the light from the exposure light source into a slit shape on the document illumination section, An illumination device for an electrophotographic copying machine, characterized in that a magnetic member is attached to a portion that does not contribute to light collection.