JPH0475512B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming apparatus in which a plurality of developing units can be attached and detached and replaced. A color copying machine separates a document into three colors (red, green, and blue) and develops the light image corresponding to each color separately with cyan, magenta, and yellow toners, which are complementary colors of each color, so a developing device is used. Requires multiple pieces. In this case, configuring the developing units separately and arranging them in parallel around the electrostatic latent image holder increases the size of the apparatus.
Therefore, a rotary type developing device has been proposed, which includes a plurality of developing devices, has a developing port for each developing device on the circumferential surface, and is rotatably provided close to the electrostatic latent image holder. Although this rotary developing device is extremely effective for miniaturization, there is a problem in that toner leaks and scatters from a developing port that is not used for development. When the leaked and scattered toner adheres to optical components, it significantly impairs optical characteristics and causes deterioration of image quality, and when it adheres to electrical components, it causes short circuits and malfunctions. Furthermore, if it adheres to the sliding parts of mechanical parts, it will significantly accelerate wear and reduce the durability of the machine. Particularly in the case of color development, if leaked and scattered toner mixes with toner in a developing device of another color, areas that are not developed with the regular toner will appear on the copy, resulting in an unsightly image. Conventionally, in order to prevent toner from leaking and scattering as described above, it has been proposed to provide a duct with a suction port around the developing device, or to surround the developing device with an elastic sponge. However, in the former case, the device becomes large and expensive. It's also very noisy. The latter is inexpensive and does not take up much space, but it is difficult to achieve a complete seal, and when used for a long time, the color mixing of leaked toner and scattered toner cannot be ignored. The present invention has been made in view of the above, and in a developing device that develops a desired color by being detachably attached to the main body of an image forming machine such as a copying machine, the present invention aims to reduce the size and weight of the attachable and detachable part. It is designed to be easily detachable and replaceable. The present invention is an image forming apparatus in which a plurality of developing devices, each of which applies a developer of a different color to an image carrier, are installed and removed at the same location to perform color switching, and in which a single developing device is installed at one location. In contrast, each of the plurality of developing devices stores a developer of a different color and can be supplied from a plurality of hoppers each having a supply port, and each of the plurality of developing devices has a developer of the same color as the developer used by itself. The image forming apparatus is characterized in that it has a supply port that communicates only with a supply port of a hopper that accommodates developer. An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic sectional view of an electrophotographic copying machine showing an embodiment of the present invention. The surface of the photosensitive drum 3 is charged by a corona charger 4 while rotating in the direction of the arrow, and a latent image of the original document exposed through the imaging element array 2 is formed on the surface of the photosensitive drum 3. The latent image is developed by being supplied with toner by the developing device 5. On the other hand, the transfer sheet P is fed onto the surface of the drum 3 by a feeding roller 6 and a register roller 7, and the toner image on the drum is transferred by a transfer charger 8. Thereafter, the sheet is separated from the drum by a separating means 9, passes over a guide 10, and is sent to a fixing device 12 by a roller 11 located at the end of the conveyance path. The toner image on the sheet is fixed by a fixing device 12, and the sheet is discharged onto a tray 14 by a discharge roller 13. Toner remaining on the photosensitive drum 3 without being transferred is collected by a cleaning device 15. 1 is a movable document table; 16 is an illumination system for exposing the document; and 17 is a heat absorption filter. 2 and 3 are enlarged views of the developing device 5 in FIG. 1. The developing device 5 is roughly divided into a hopper-type developer container section 18 and a developing section 19 that supplies developer to the photosensitive drum and develops a latent image. Developing section 1
9, 20 is a developing roller, 21 is a developer layer thickness regulating member, and 22 is a stirring member. Developing section 1
9 is slidable and detachable on the copying machine main body rail 23, so that it can be completely separated from the developer container section 18 . A slot-shaped replenishment port 19b is provided in the upper part of the developing section 19 along the central axis of the photosensitive drum. Inside the developer container section 18 , hoppers 18a, 18b, and 18c containing developer are arranged side by side. A slot-shaped supply port is provided below each hopper in the direction of the central axis, and the supply port is provided with supply rollers 24a, 24b, and 24c for controlling the amount of developer supplied. The replenishment port of the developing section that uses the developer of the hopper 18a is positioned so as to correspond to the supply port as shown in FIG. In the state shown in FIG. 2, the developing section 19 is formed so that only the replenishment roller 24a is drivably switched. Therefore, developer is not replenished from the hoppers 18b and 18c. FIG. 3 shows a case where the developing section is replaced with a dedicated device for the hopper 18b. A supply port 25b is provided at the center corresponding to the supply port of the hopper 18b. The replenishment rollers 24a and 24c do not operate, and the replenishment roller 24b operates based on a signal from the copying machine main body to appropriately replenish developer into the developing section 25 . 2
Reference numeral 9 denotes a lid for each hopper, from which developer is supplied separately for each color. The hopper capacity does not need to be the same for each color, and the hopper capacity for frequently used colors can be increased. In the example, the hopper 18a is red, the hopper 18b is blue,
The capacity of 18c is increased to store black developer. According to the present invention, when attaching and detaching a developing device to an image forming apparatus, only the developing device can be attached and detached at the same place while leaving a plurality of hoppers in the image forming apparatus main body. Since the structure is such that the developer is supplied from the image forming apparatus, it is possible to provide an image forming apparatus that has a compact attachment/detachment section and is capable of performing multicolor development.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of an electrophotographic copying machine showing an embodiment of the present invention, and FIGS. 2 and 3 are enlarged views of the developing device shown in FIG. 1. 18a, 18b, 18c...hopper (developer storage means), 19 , 25 ...developing section (developing means),
19b, 25b...Developer supply port, 24a, 24
b, 24c... Replenishment roller (developer supply means).

Claims (1)

[Claims] 1. An image forming apparatus in which color switching is performed by attaching and detaching a plurality of developing devices each applying a different color of developer to an image bearing member at the same location, where each developing device has different colors for one developing device installation location. It can be supplied from a plurality of hoppers each having a supply port, and each of the plurality of developing devices accommodates a developer of the same color as the developer used by itself. An image forming apparatus characterized in that it has a supply port that communicates only with a supply port of a hopper.