JPH083672B2 - Color image forming device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a color image forming apparatus such as a color copying machine or a color printer.

(Prior Art) Many color image forming apparatuses such as full-color copying machines and color printers have been proposed. In such a color image forming apparatus, the one adopting the electrophotographic system is provided with a developing device of four colors in which black is added to the three primary colors of cyan, yellow and magenta, and the process is repeated many times. Various proposals have been made for a mechanism such as color matching.

An example of such a color image forming apparatus is as follows.

The first form is JP-A-61-29860 or JP-A-56.
As described in Japanese Patent Laid-Open No. 132355, a developing device accommodating a developer of each of the colors 3 and 4 separately for a single photosensitive member support is selectively put into an operating state, A sheet in which an electrostatic latent image corresponding to the developer color of the developing device is formed on the photoconductor of the photoconductor support, the electrostatic latent image is visualized by the developing device, and then the visualized image is supported by the transfer drum. A color image forming apparatus configured to obtain a color image in which the respective colors are superposed by transferring the image to a member, terminating the processing for the first color, and then sequentially performing the same operations as described above while setting the developing devices for the other colors in the operating state. Is.

The second form is JP-A-59-50460 or JP-A-59-50.
No. 204069, a plurality of image forming means are provided, and each of the plurality of image forming means has a photoreceptor supporting means having a photoreceptor on the surface and a static image formed on the photoreceptor. Not only a developing device that visualizes a latent electric image (as well as a corona discharger for charging to uniformly charge the surface of the photoconductor and a cleaning unit that cleans the surface of the photoconductor), but also an image forming light on the photoconductor. A transfer corona discharger for transferring the visible image on the photoreceptor to the sheet member, and a plurality of image forming means are sequentially actuated with the movement of the sheet member. The color image forming apparatus is configured to obtain a color image in which the respective colors are superimposed.

(Problems to be Solved by the Invention) In the image forming apparatus of the first embodiment, since a plurality of developing devices are selectively acted on a single photoconductor, the photoconductor or other There is a possibility that a plurality of toner particles having different colors may be mixed with each other through the constituent elements. Further, as is well known to those skilled in the art, it is generally important that the developing device is positioned extremely precisely with respect to the photoconductor, but in the case of a configuration in which a plurality of developing devices are appropriately moved to a working position, a single device is used. It requires a rather complicated and expensive moving mechanism, if not impossible, to position it extremely precisely and selectively with respect to the photosensitive member.

In addition, in the image forming apparatus of the second embodiment, it is necessary to dispose a plurality of light projecting means and a corona discharger for transfer, and therefore, the size of the apparatus becomes extremely large and the cost becomes extremely high. There is.

The present invention has been made in view of the above facts, and its main technical problem is a new and improved color image capable of generating a full-color image without the above-mentioned problems or drawbacks in the conventional color image forming apparatus. A forming device is provided.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, a photosensitive member support having a photosensitive member on its surface and a development for visualizing an electrostatic latent image formed on the photosensitive member. A plurality of image forming means each including a device, and each of the developing devices stores toner particles of mutually different colors necessary for forming a color image, and any one of the plurality of image forming means Common transfer paper having a moving mechanism for selectively positioning the image forming area, a common light projecting means arranged in association with the image forming area, and a transfer means arranged in association with the image forming area. The toner color accommodated in the developing device of the image forming unit positioned in the image forming area is provided with a supporting member and a sheet member conveying mechanism for conveying the sheet member toward the common transfer paper supporting member. The common light projecting means applies the corresponding image forming light onto the photoconductor. An electrostatic latent image is formed on the photoconductor by projection, and the electrostatic latent image is visualized by the developing device of the image forming means, and the visualized image is supported by the transfer paper support member. A color image is formed by performing the multi-transfer on the sheet member by transferring the image to the sheet member by the action of the transfer unit, and then positioning the other image forming unit in the image forming area and repeating the above operation. A device is provided.

(Advantageous Effects) In the image forming apparatus of the present invention, since the photoconductors are arranged so as to correspond to the plurality of developing devices, respectively, the photoconductors are accommodated in the developing devices via the photoconductors and are different from each other. There is no risk of color toner particles mixing in. Further, since the light projecting means, the transfer means, the transfer paper holding member and the like are commonly used for a plurality of image forming means, it is possible to minimize the size increase and cost increase of the apparatus.

(Example) The present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic view showing a component type color image forming apparatus of the present invention. The component type color image forming apparatus indicated by 2 as a whole includes a color image exposing optical system unit A from the upper part of the drawing, a toner image forming unit B below it, and an intermediate tray unit D for double-sided copying below it. The lowermost part is composed of a copy paper feeding unit C including two copy paper feeding units E1 and E2.

Then, these units are stacked in a predetermined positional relationship by the positioning mechanism 1 provided on the upper surface of each unit to form one image forming apparatus 2.

The color image exposure optical system unit A includes, for example, a document placing section 4 and a color image optical system having a color separation function known per se using a filter or the like. In the actual exposure, a color original document (not shown) placed on the original document placing section 4 is scanned and exposed by a light source 5 having an emission spectrum over all visible light, and is irradiated by the light source 5. The document surface is guided to the optical system 6 as an optical spot. In this optical system 6, a color separation filter of cyan, yellow, magenta or the like is used to decompose the light into a specific color light, and the separated light is guided to a toner image forming unit B through an exposure opening 7 provided on the lower surface of the unit A.

The toner image forming unit B has an exposure opening 10 provided on the upper surface of the unit housing 8 in a positional relationship corresponding to the exposure opening 7 of the unit A. Then, the hanging part of the exposure opening 10 is used as an operating position for image formation,
Three image forming units 12, 14, 16 provided with yellow and magenta colored toners are arranged in a horizontal row so as to be movable in the horizontal direction.

The image forming units 12, 14, and 16 have basically the same structure except that the toner colors are different.

Specifically, a main charger 13, a developing device 15 having colored toner, and a cleaning device 17 are arranged in this order around the photosensitive drum 11 as a center. The uppermost position and the lowermost position of the drum 11 of the image forming unit 12 are exposed as a master exposure area and a transfer area. Of the exposure areas of the three image forming units 12, 14 and 16, the image forming unit (unit 14 in the figure) corresponding to the position corresponding to the exposure opening 10 of the unit B is the operating position.

A transfer drum 18 is rotatably provided in the hanging portion of the transfer area T of the image forming unit 14 located at the operating position.
A transfer charger 19 is provided inside the transfer drum 18 at a position corresponding to the transfer area T. A copy paper conveying path 20 extending from the lower right to the lower left in the drawing is formed so as to largely surround the transfer drum 18. More specifically, the first paper feed conveyance path 20a from the manual paper feed port 22 provided on the lower right side surface of the housing 8 of the unit B to the transfer area T, and the lower surface side of the housing 8 in the drawing as well. There is a second paper feed conveyance path 20b from the automatic paper feed opening 24 provided on the right side to the transfer area T, and these two conveyance paths 20a and 20b merge in the transfer area T and are located at the lower left of the unit B. It reaches the fixing device 26 provided.

The copy paper that has passed through the transport path 20 and the fixing device 26 is discharged to the outside of the unit B through a discharge opening 28 provided on the left side surface of the housing 8 of the unit B. Further, the discharge tray 27 may be directly provided in the discharge opening 28, and an intermediate tray unit D for double-sided copying as shown in the drawing is arranged below the unit B so that the discharge tray 27 is automatically operated through the opening 28. It is also possible to form a circulation path 30 reaching the paper feed opening 24.

The intermediate tray unit D will be described in detail. The unit D is a unit body formed as a substantially L-shaped housing body that can be connected to two openings, a discharge opening 28 to the unit and an automatic paper feed opening 24. Is. The discharge opening 28 of the unit B is formed with a first transport path 38 that extends from an opening 29 provided at a position corresponding to the opening 28 to a paper discharge port 31 provided on the left side surface of the unit D. ing. A switching lever 40 is provided at an intermediate position of the conveyance path 38, and the circulation path 30 for guiding to the intermediate tray 36 provided at the center of the unit D and the first conveyance path 38 leading to the discharge port 31. And switching. Further, a pair of rollers 39 capable of rotating in the forward and reverse directions is provided on the side of the paper discharge port 31 of this conveyance path, and is configured to discharge the copy paper and carry it for double-sided copying.

Further, a pair of rollers 44 capable of rotating in the forward and reverse directions is provided in the circulation path 30. Now, by switching the switching lever 40 toward the circulation path 30 and rotating the roller pair 44 in the forward direction, the fixing device 26
The copy paper exiting from is temporarily guided to the circulation path 30 reaching the intermediate tray 36, and immediately after the trailing end of the copy paper passes the switching lever 40, the roller pair 44 is reversed. As a result, the copy paper is guided by the reverse rotation of the roller pair 44 to the discharge port 31 with the rear end of the copy paper located near the switching lever 40 as the front end. Due to this reversing action, the front and back sides of the copy paper are reversed, and the copy paper is ejected with the side different from that when directly ejecting the paper. Therefore, by using the switching lever 40, it is possible to freely discharge the front and back surfaces of the copy paper.

On the other hand, when performing double-sided copying, the copy lever is temporarily guided to the first transport path 38 by using the switching lever 40, the forward / reverse rotatable roller 39 and the intermediate tray 36 located in the vicinity of the sheet discharge port 31, The copy paper is switched back by the forward / reverse rotatable roller 39, and the copy paper is circulated to the intermediate tray 36 while the front and back sides are switched by the switchback.

An opening 51 is provided on the lower surface of the housing 8 of the unit D so that copy paper automatically fed from a paper feeding unit C described later can be conveyed. A bypass passage is formed in the lower surface of the B housing 8 to reach the opening 24.

Next, the copy paper feeding units E1 and E2 will be described. The paper feed units E1 and E2 have basically the same structure. For example, E1 is a unit for automatically feeding a copy paper of a relatively large size, and E2 is a unit for automatically feeding a copy paper of a relatively small size. Has become.

Specifically, the paper feed cassette 50 arranged on the left side in the drawing
A sheet feeding roller 52 for feeding the copy sheets in the sheet feeding cassette 50 one by one, and a sheet feeding roller 52 provided from the sheet feeding cassette 50 to the upper right side of the units E1 and E2. The automatic paper feed opening 24 or a paper feed passage 56 to the bypass passage inlet opening 51, and a bypass passage 58 similar to that provided in the unit D.

In the color image forming apparatus described above, the first important feature of the present invention is that the color image forming apparatus is divided into units A, B, D, and C based on the function of each of the image forming apparatuses, and is configured as necessary. That is, these are combined to form one image forming apparatus. As described above, by forming the unit body, the image forming apparatus becomes an analog type image forming apparatus by combining the toner image forming unit body B as the core and A and C. Further, by combining A, D, and C, an analog image forming apparatus capable of double-sided copying can be obtained.

On the other hand, if the exposure optical system unit A is replaced with, for example, a digital type exposure unit A ′ using a deflector with a polygon mirror using a laser as a light source, it will be possible to function as a digital type color printer in the future. In this way, it is possible to provide a versatile image forming apparatus.

Moreover, since the positioning mechanism 1 is provided in each unit, the respective openings can be smoothly connected and the respective functions can be effectively exerted regardless of the combination of any units.

The second feature of the present invention is the transport path 20 of the color toner image forming unit B. That is, the transport path 20 is formed so as to pass through the transfer area T formed between the transfer drum 18 and the unit group of the image forming units 12, 14, 16 arranged in a line.

With this configuration, when performing mono-color copying,
By moving the copy paper along the transport path 20 to transfer the color toner from the image forming unit having an appropriate color toner in the image forming state in the transfer area T, and directly send it to the fixing device 26 through the transport path 20. You can As a result, monocolor copying can be performed without involving the transfer drum,
Although it is a color copying machine, it can form a toner image at the same high speed as a normal copying machine.

Then, in the case of performing full color, while copying the copy paper that has passed through the transport path 20 with the first color toner,
The copy paper is fixed on the transfer drum 18 by using a fixed guide pin 100 provided on the transfer drum, and the toner image of each color is transferred plural times in synchronization with the rotation of the transfer drum 28.
After the desired color toner image is transferred, the fixed guide pin 100 is released, the copy paper is removed from the transfer drum 18 and again sent to the conveyance path 20 and guided to the fixing device 26. As a result, the transfer drum can be interposed only when full color or a plurality of colors are used. Moreover, by synchronously controlling the rotation of the transfer drum and the cycle of the toner image forming process, it is possible to reliably obtain a color copy without color misregistration.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a component type color image forming apparatus of the present invention, and the reference numerals in the figure represent the following contents. 1 ...... Positioning mechanism 2 ...... Component type color image forming device 12, 14, 16 ...... Image forming unit 18 ...... Transfer drum 20 ...... Conveyance path A ...... Color image exposure optical system unit B ...... Toner image creation Unit D …… Intermediate tray unit E1, E2 …… Paper feeding unit T …… Transfer area

Claims (1)

[Claims] 1. A photosensitive member support having a photosensitive member on its surface, and a developing device for visualizing an electrostatic latent image formed on the photosensitive member, each of which includes a color image forming device. A plurality of image forming means for accommodating toner particles of mutually different colors, a moving mechanism for selectively positioning any one of the plurality of image forming means in an image forming area, and the image forming means. A common light-transmitting unit arranged in association with the area, a common transfer paper supporting member having a transfer unit arranged in association with the image forming area, and a sheet member facing the common transfer paper supporting member. A sheet member transport mechanism for transporting the image forming light corresponding to the toner color accommodated in the developing device of the image forming means positioned in the image forming area, and the common light projecting means onto the photoconductor. When projected, an electrostatic latent image is formed on this photoconductor,
The electrostatic latent image is visualized by the developing device of the image forming means, the visualized image is transferred to the sheet member supported by the transfer paper supporting member by the action of the transfer means, and then the other image forming means. A color image forming apparatus which forms a color image by performing multiple transfer to a sheet member by positioning the image forming area in the image forming area and repeating the above operation.