JPH0337001Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention is a method of obtaining color copies by using a plurality of photosensitive drums to create color-separated images, and transferring them multiple times onto a single sheet of paper. The present invention relates to a color image forming apparatus.

Conventionally, in a color copying machine equipped with a plurality of photoconductor drums, after forming color-separated original toner images on each photoconductor drum, the photoconductor drums are reversed and the transfer paper is transferred in the direction in which the document table is fed. A method has been proposed in which the color-separated toner images are sequentially transferred onto a transfer paper by conveyance using a belt to obtain a color copy. However, during the exposure process for one of the photoconductors, if the other photoconductor is reversed, load fluctuations will occur in the drive system, and the impact of load fluctuations due to the stop and return operations of the document table during the transfer process. Therefore, jitter may occur, causing color shift in the transferred image. Therefore, in order to eliminate the above-mentioned inconvenience, the photoreceptor drums are rotated only in one direction without being reversed during image formation and transfer, and all the photoreceptor drums are connected and interlocked by a gear mechanism. To obtain good color copies with no or inconspicuous color deviations by adjusting the stop and return timings of a document table during a yellow image transfer process in which color deviations are relatively inconspicuous even if they occur. Newly developed color copying machines have been developed.

Purpose The present invention provides the above-mentioned new color copying machine.
Static electricity is removed before or during transfer of the toner image on each photoreceptor drum using light of a wavelength that passes through the color toner from a different light source for each color, that is, light of a color other than the color complementary to the toner color. The purpose is to efficiently transfer the toner image to the transfer paper using the transfer paper, thereby obtaining color copies of good quality.

Composition Below, the present invention is shown in the drawings in cyan, magenta,
An embodiment using a color copying machine equipped with a transfer station using a three-color yellow photosensitive drum will be described.

FIG. 1 is a sectional view showing a schematic configuration of a color copying machine according to the present invention, which includes a document illumination device, an exposure lens device, a photosensitive drum, a main charger, a developing device, a pre-transfer charger, a transfer charger, and a quenching lamp. For example, three electrophotographic devices are installed in series, each of which performs cyan development, magenta development, and yellow development, and a document placed on the document table on the top of the copying machine is sequentially transferred to each electrophotographic device. Images are fed, exposed, and separated into three colors to be formed on each photoreceptor drum, and the toner image on each photoreceptor drum is transferred in the opposite direction to the direction in which the document table is fed for exposure. The color separation images are transferred from each photosensitive drum in the reverse order to a transfer sheet that is conveyed on a transfer belt.

Therefore, each electrophotographic device will be described as a first transfer station (cyan) C, a second transfer station (magenta) M, and a third transfer station (yellow) Y according to the exposure order of the originals placed on the original table. .

In FIG. 1, a document table 2 is illuminated on the upper surface of a color copying machine 1 while being moved from left to right, and color-separated images are formed on each photoreceptor drum at each transfer station. The document mounting table 2 is designed to return to the initial position in preparation for the next process.

The first transfer station C includes an original (red light) illumination device 3, an exposure lens device 4, and a photoreceptor drum 5.
c, a main charger 6, a developing device 7c, a pre-transfer optical static eliminator 8, a transfer charger 9c, and a quenching lamp 10, and exposes the image from the original document to red light to form a cyan toner image on the photoreceptor drum 5c. Transfer belt (Mylar 100μ) 11 to be formed and described later
A cyan image is transferred onto the transfer paper 12 that is transferred by the quenching lamp 10, and the photoreceptor drum 5c is charged again by the main charger 6, and the photoreceptor drum 5c is charged again by the quenching lamp 10, and the same operation can be repeated. It is becoming. However, until the toner image on the photoreceptor drum is transferred, unnecessary chargers and the like are not operated.

The second transfer station M performs the same work as the first transfer station C, but here, a magenta toner image is formed on the photoreceptor drum 5 m by green exposure, and the third transfer station Y uses blue exposure. A yellow toner image is formed on the photosensitive drum 5y.

Each photoreceptor drum has the same diameter D and is configured to be driven by the main motor 13 via a gear, and the interval between each photoreceptor drum is half the drum circumference length (πD/2). Transfer chargers 9c and 9c are provided on the bottom surface of each photoreceptor drum, respectively.
9m and 9y are provided facing each photoreceptor drum via a transfer belt 11 that commonly contacts each photoreceptor drum.

This transfer belt 11 is adapted to transport the transfer paper in the direction opposite to the direction in which the document table 2 is transported for exposure, and is stretched around support rolls 14 and 15 so as to contact each photoreceptor drum. One of the supporting rolls 14 is driven by a timing belt 16 from the main motor 13, and is charged by a transfer belt charging device 17 provided on the outside of this supporting roll (rubber roll) 14. The transfer paper 12 sent through the transfer roller 19 is electrostatically attracted and sent to the photoreceptor drum of each station, and after the toner image of each color is transferred to the transfer paper by the transfer charger, the curvature of the support roll (separation roll) 15 is The transfer paper is separated and transferred to the fixing device 20 side by the separating action.

Note that the registration roll 19 is driven by the timing belt 16 in the same manner as the support roll 14.

The transfer belt 11 also includes an auxiliary support roll 2.
1 and 22 are provided to prevent the transfer belt from bending downward, and furthermore, the transfer belt facing the photoreceptor drum 5c of the first transfer station C is
The support roll 15 is connected to the transfer charger 9c by means of an arm rod 24 that can swing around a support shaft 23 so as not to come into contact with the photoreceptor drum 5c except when necessary.
It is said that it is possible to displace downward with the same movement. Similarly, the photosensitive drum 5m at the second transfer station M
However, by downward displacement of the auxiliary support roll 22, the transfer belt 11 is lowered to a position where it does not come into contact with the transfer belt 11. Further, reference numeral 25 is a static eliminator for the transfer belt, 26 is a cleaning device, and 27 is a shutter for keeping the exposure section closed except when necessary.
It is.

As described above, in the color copying machine of the present invention, the photoreceptor is photostatically neutralized by the pre-transfer optical neutralization sending device 8 immediately before or simultaneously with the transfer of the toner image onto the transfer paper 12 at each station, and the It is designed so that the potential of the photoreceptor is erased and the toner image on the same surface is transferred to the transfer paper from the front, but the color of the toner on the photoreceptor is different for each station. However, if a light source that emits a color with a wavelength that is absorbed by the toner is used for photostatic charge removal, the light will not reach the photoreceptor, and even if it does, it will only reach partially, making static removal ineffective. This makes it difficult to carry out the process, which has a negative impact on the next process. In short, in order to effectively eliminate static electricity by photoreceptor, it was necessary to use light with a wavelength that would allow the light to pass through the color toner applied to the photoreceptor and reach the surface of the photoreceptor. It is necessary to install a light source for optical static elimination that emits different colors.

Therefore, in the color copying machine of the present invention, an optical static elimination light source that emits light of a wavelength other than blue is used for the yellow image forming photoreceptor 5y, and a non-green light source is used for the magenta image forming photoreceptor 5m. A light source that emits light with a wavelength of , and a light source for optical static elimination for the cyan image forming photoreceptor 5c are lights with wavelengths other than red, respectively. Entire transfer of the toner image from the photoreceptor to the transfer paper surface occurs uniformly and effectively without absorption by the toner image by erasing the potential on the photoreceptor before or at the same time as transfer. That's what I do.

Therefore, the wavelength of the light emitted from the light source of the pre-transfer optical static eliminator 8 of each station in the color copying machine shown in the first figure is different for each station, and the conditions for the wavelength are as described above. It is. Note that members such as LEDs and light emitting elements can be used as those light sources.

By the way, in the case of the color copying machine of this embodiment, the color of the light source for optical static elimination that satisfies the above conditions for the photoconductor of each station is the color of the light source of the illumination device 3 for color separation exposure of the document in the adjacent station. Since this is consistent with this, a method can be considered in which light from the same light source is used to optically eliminate the potential of the photoreceptor before or at the same time as the transfer.

FIG. 2 is a sectional side view of main parts of another embodiment of the color copying machine of the present invention in which the above technology is implemented, and the same figure shows the document illumination device and the photoreceptor in the side sectional view of the copying machine shown in FIG. 1. Since only constituent members related to static elimination before or during transfer are extracted, explanations of the attached symbols will be omitted. However, in the figure, 28 is an independent light source for optical static elimination, and the wavelength of the light is green or red. 29 is a mirror, R is a red light source, G is a green light source, and B is a blue light source. This indicates that The light source 28 corresponds to the pre-transfer optical static eliminator 8 in the third transfer station in the first illustrated embodiment, and the color of its light is conditioned as described above.

The reason why the independent light source for optical charge removal was installed at the third transfer station was because of the positional conditions for optical charge removal before or during transfer of the photoreceptor at the third transfer station. Due to the reason that it is difficult to do.

Of course, it is possible to bring in light from other stations using an optical fiber bundle, but a method that is advantageous in terms of space, structure, or cost should be adopted. Note that an LED, a light emitting element, etc. can be used as the light source.
In addition, in the illustrated case, the projected light is once reflected by a mirror 29 and reaches the surface of the photoreceptor due to the relative relationship between the illumination device 3 at each station and the pre-transfer neutralization position of the photoreceptor drum. However, it goes without saying that an optical path changing member such as a prism may be used for this purpose, or direct light may be irradiated if possible.

In the embodiments described above, the case of a color copying machine consisting of three transfer stations equipped with three photoreceptor drums has been described.
The photostatic charge removal method of the present invention can also be applied to a copying machine having two photoconductors within the scope of the same explanation and technology as above by arranging a yellow image forming photoconductor at the final stage of the copying machine. I can do it.

Effects According to the color copying machine of the present invention, by using light with a different wavelength for each station as a light source for optical static elimination on the photoreceptor before or during toner image transfer, the color of the color image formed on the photoreceptor can be changed. Regardless of the difference, the static eliminating light can reach the surface of the photoreceptor and eliminate the potential uniformly and effectively.
The subsequent transfer of the toner image is performed efficiently, and high-quality color copies can be obtained.
The color conditions of the light source for optical static neutralization of the photoconductor at that station match those of the light source of the document illumination device of the adjacent station, so if the projected light from there is guided and used, it is not necessary to install a new light source for optical static neutralization. Moreover, since the light from the light source of the illumination device of the adjacent station is used, there is an advantage that the means for guiding the projected light is simple and easy. Therefore, compared to the copying machine shown in the first drawing, this copying machine is effective in reducing costs by reducing the number of products, making effective use of machine space, and reducing assembly man-hours.

[Brief explanation of the drawing]

FIG. 1 is an overall sectional view showing a schematic configuration of one embodiment of the color image forming apparatus of the present invention, and FIG. 2 is a side sectional view of a main part of another embodiment. 1...Color copying machine, 3...Document illumination device, 4
...Exposure lens device, 5...Photosensitive drum, 8...
...Pre-transfer optical static eliminator, 9...Transfer charger, 2
8... Light source for optical static elimination, 29... Mirror, C... First transfer station (cyan), M... Second transfer station (magenta), Y... Third transfer station (yellow), B... Blue Light, G...Green light, R...Red light.

Claims (1)

[Scope of Claim for Utility Model Registration] A photoconductor, means for color-separating an original image and forming an electrostatic latent image for each separated color on the photoconductor, and dividing the electrostatic latent image into yellow, magenta, and yellow for each color. means for developing each color with a cyan toner; means for transferring the developed image of each color to the photoreceptor before or at the same time as the transfer;
A color image forming apparatus characterized by comprising means for irradiating light of a color other than a color complementary to the toner color of each of the developing means.