JPH0736368Y2 - Multicolor electrophotographic device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field of the Invention The present invention provides a black developing device for developing a black toner on an electrostatic latent image formed on a photoreceptor and a multi-color developing device for developing other color toners. The present invention relates to a multicolor electrophotographic apparatus having the same.

2. Description of the Related Art Multicolor electrophotographic apparatuses of the above type are well known and are, for example, electrophotographic copying machines, laser printers, facsimiles and the like.
Various multicolor methods have been proposed for this type of device. Among them, recently, a method of superimposing a multicolor image on a photoconductor, developing the image, and then transferring the image on a transfer paper at a time has attracted attention as a simple recording.

In this method, it is advantageous to use a non-contact type developing device as the developing method for the second and subsequent colors so as not to disturb the toner image previously formed. However, the non-contact type developing device has problems such as poor sharpness and insufficient resolving power as compared with the contact type developing device, and becomes a big problem particularly as a developing device for black toner which is generally used.

Therefore, it has been proposed that the black toner is used as the first color to be developed by the contact type developing device, and the second and subsequent colors are developed by the non-contact type developing device. The thus configured multicolor electrophotographic apparatus can provide good sharpness and resolution for development with black toner.

However, in this multicolor electrophotographic apparatus, if a drum-shaped photoconductor is used and a contact type developing device is adopted, the developing device that can be used is limited in terms of contact margin. Furthermore, using a drum photoconductor will result in a large diameter drum with a perimeter longer than the maximum recording size,
There is a problem that the device becomes large.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention solves the above-mentioned problems of the related art, and aims to provide a multicolor electrophotographic apparatus which is excellent in sharpness and resolution in development with black toner and does not increase the size of the apparatus. There is.

Means for Solving the Problems The constitution of the present invention which achieves the above object is as follows.

In a multicolor electrophotographic apparatus having a black developing device for developing a black toner on an electrostatic latent image formed on a photoconductor and a multicolor developing device for developing other color toners, a belt photoconductor as the photoconductor, A contact developing device is used as the black developing device, and a non-contact developing device is used as the multi-color developing device, and the developing position of the black developing device is at a position where there is no backup member of the photoconductor belt. A multicolor electrophotographic apparatus, characterized in that the developing devices of the multicolor developing device are respectively arranged at the positions where the backup members of the photoconductor belt are provided.

Action According to the above configuration, the belt photosensitive member is used as the photosensitive member,
Since the black toner is developed by contact development, the size of the apparatus does not increase, and the development of the black toner has sharpness and resolution. However, in the case of combining a belt photosensitive member and a non-contact type developing device, if the developing device is opposed to a portion without a backup portion, it becomes difficult to control the distance between the two. On the other hand, in the contact type developing device, if the developing device is arranged so as to face the non-backup portion, the contact can be made with a very weak pressure, and the dimensional margin can be greatly improved.

Therefore, by deciding the arrangement of the contacting / non-contacting developing device depending on the presence / absence of the backup member, it is possible to prevent problems by using the belt photosensitive member.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is an explanatory view showing an embodiment of the electrophotographic apparatus according to the present invention.

In FIG. 1, reference numeral 1 is a photoconductor belt, the photoconductor belt 1 is wound around rollers 2 and 3, and the photoconductor belt 1 is rotated by driving one of the rollers 2 and 3 to rotate. The vehicle runs in the direction of arrow A. Around the photoconductor belt 1, in the traveling direction, a charging charger 4, a developing device 5 for colors other than black, a developing device 6 for black, a transfer charger 7, a cleaning device 8 and a charge eliminating lamp 9 are arranged. 4 is image-exposed between the red developing devices 5 by the arrow L.

In the developing device 5 for red, the developing roller 5a is the photosensitive belt 1.
In the non-contact type developing device, the developing roller 5a is arranged so as to face the winding portion of the roller 3. On the other hand, the black developing device 6 includes the developing roller 6a.
Is a contact type developing device that contacts the photosensitive belt 1, and is arranged so as to contact the photosensitive belt 1 while the rollers 2 and 3 are running. That is, the developing device 5 for red has its developing position at a position where the roller 3 has the roller 3 as a backup member for the photoreceptor belt 1, and the developing device 6 for black has its developing position at a position without a backup member. There is.

With such an arrangement, since the red developing device 5 is located at the position where the roller 3 is provided, it becomes easy to control so that the distance between the developing roller 5a and the photosensitive belt 1 is constant, and stable development can be obtained. Further, since the developing device 6 for black has no roller, the developing roller 6 can be brought into contact with it with a very weak pressure, and since there is a large range without backup, the dimensional margin can be greatly improved. .

Next, an operation mode for forming a red two-color image with the electrophotographic apparatus shown in FIG. 1 will be described.

First, in the first rotation of the photoreceptor belt 1, the light image corresponding to the black toner is exposed on the portion charged by the charging charger 4 to form the latent image. Then, the red developing device 5 is deactivated, and the latent image is developed only by the black developing device 6 to form a black toner image. This toner image is transferred to the transfer charger 7 and the cleaning device 8.
However, at this time, the transfer charger 7 is deactivated, and the cleaning device 8 holds the cleaning blade 8b at a position separated from the photosensitive belt 1 via the pin 8a. As a result, the photoconductor belt 1 makes one rotation, and then the second time.

In the second time, the latent image corresponding to the red toner is formed on the black toner image in the same manner as above. Then, this latent image is developed by operating the red developing device 5,
As a result, two color toner images of red and black are formed. When the toner image passes through the area of the black developing device 6, the black developing device 6 is rotated about the pin 6b so as not to be disturbed by the developing roller 6a. Keep it away from belt 1.

The two-color toner images formed in this manner are transferred by the action of the transfer charger 7 to the transfer paper 10 that is conveyed in synchronization with the toner images. After the transfer, the photosensitive belt 1 is cleaned by the cleaning device 8 in which the residual toner is returned to the cleaning position, and the residual charge is removed by the charge eliminating lamp 9 to prepare for the next copying.

As described above, the black developing device 6 which is a general purpose in the present invention is used.
Since the image of the contact developing system is adopted, the image does not have poor sharpness and lack of resolution, and the red developing device 5 which is developed later uses the non-contact developing system. It also eliminates the disturbance of the previous toner.

FIG. 2 is an explanatory view showing another embodiment of the present invention,
In this embodiment, a red developing device 5 and a blue developing device 11 are provided in the multi-color developing. These multi-color developing devices
Reference numerals 5 and 11 are both non-contact developing systems, and developing rollers 5a and 11a thereof are arranged opposite to the winding portions of the roller 3 and the roller 12. Further, the photosensitive belt 1 is wound around the rollers 2, 3 and 12, and the image forming constituent units are arranged around the photosensitive belt 1 as in the above-described embodiment.

In the electrophotographic apparatus having the above structure, toners of respective colors are sequentially superposed in the same manner as described above to obtain a multicolor copy.

Effects According to the above configuration, the present invention adopts the contact developing method for the black developing device and the non-contact developing device for the multicolor, so that the sharpness and resolution are improved in the development with the black toner, and the photoreceptor belt is used. Therefore, it was possible to prevent the photoconductor from becoming huge.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of an electrophotographic apparatus according to the present invention, and FIG. 2 is an explanatory view showing another embodiment of the present invention. 1 ... photosensitive belt 2,3,12 ... roller 5 ... red developing device 6 ... black developing device 11 ... blue developing device

Claims (1)

[Scope of utility model registration request] 1. A multicolor electrophotographic apparatus having a black developing device for developing a black toner on an electrostatic latent image formed on a photoconductor and a multicolor developing device for developing other color toners, wherein the photoconductor As a belt photosensitive member, a contact type developing device as the black developing device, and a non-contact type developing device as the multicolor developing device, the developing position of the black developing device is a backup member of the photoconductor belt. A multicolor electrophotographic apparatus, characterized in that the developing apparatus is arranged at a non-existing position, and the developing position of the multicolor developing apparatus is arranged at a position where the backup member of the photosensitive belt is present.