JPS6249378A - Developing device for single color copying machine which permits color selection - Google Patents

Abstract

PURPOSE:To obtain a dark and good image density regardless of the kind of an original by changing over development time according to the image condition of the original and the kind of a developer. CONSTITUTION:The change-over of the development time is made possible according to the image condition of the original and the kind of the development. For example, electrostatic charging, erasing, exposing and developing are executed in the conventional manner in the 1st copying; thereafter, the rotation of a photosensitive drum 1 is continued while the transferring, separating, cleaning and destaticizing are not-operating. The drum 1 is subjected to the 2nd rotation in succession thereof and in this stage the charging, erasing and exposing are in the non-operating state but the developing, transferring, separating, cleaning and destaticizing are operated. Since the development is eventually executed twice during one copying process with the drum 1, the deposition of the developer increases and the developing power improves. As a result, the reproducibility of the solid image improves as well.

Description

DETAILED DESCRIPTION OF THE INVENTION Limb Blood Separation The present invention relates to a developing device for a monochromatic copying machine that allows color selection.

[Theft] U1 has recently been used not only for black copies, but also for other chromatic colors, such as blue,
Monochromatic copying machines that can make copies in any desired color, such as sepia or red, are commercially available.

A developing unit conversion method is a common method for changing copy colors. The developing device is configured as a single unit that is not removable, and normally a developing unit containing black developer is installed, but when you want to change the color, you can attach the poster to the one containing developer of other colors. Their properties vary widely, such as those that emphasize so-called solid images that cover a wide area of the same color screen.

If originals with different image properties are developed in the same way, the resulting image quality will differ.

It was used to obtain a black copy of a document having an image mainly composed of lines such as conventional characters. When a solid image such as a poster is copied using a chromatic developer using such a copying machine, there is a problem in that the developer fills the image area unfavorably, resulting in insufficient image density.

Shell m The present invention solves the above-mentioned problems of the color-selectable monochrome copying machine, and provides a developing device for the color-selectable monochrome copying machine that can obtain a deep and good image density regardless of the type of document. It is intended to.

1. The present invention has achieved the above object by switching the developing time depending on the image condition of the original and the type of developer.

The structure and operation of the present invention will be explained in detail based on the embodiment shown in the drawings.

In FIG. 1, along the rotational direction of an electrostatic latent image carrier 1, for example, a photoreceptor drum, a charging charger 2, an erase lamp 3, an exposure position 4 by an exposure optical system, a developing device 5, a transfer charger 6, a cleaning device 7, A static elimination lamp 8 is arranged in a known manner.

The developing device 5 has a first developing unit 10 containing a chromatic developer and a second developing unit 20 containing a black developer.

The first developing unit 10 has a developing sleeve 11 having a developing magnet (not shown) provided therein, and an agitating roller 12, and is supplied with toner from a toner hopper 13 by a toner replenishing roller 14.

Similarly, the second developing unit 20 includes a developing sleeve 21, a stirring roller 22, a toner popper 23, and a toner supply roller 2.
4. The structure of the developing unit itself is otherwise the same as a known one, so a description thereof will be omitted.

When copying, use the second unit 2 for black copying.
0 is used for chromatic copying, the first developing unit 1 is used.
0 is used. The other developing unit, which is not used, is inactive and does not supply developer to the photoreceptor drum.

During copying, first the surface of the photosensitive drum 1 is uniformly charged by the charger 2, and then the charge on unnecessary portions is removed by the erase lamp 3.

The charged portion of the photoreceptor drum 1 is exposed at an exposure position 4 to form an electrostatic latent image, which is developed and visualized by a developing device 5, and is transferred to a transfer paper 9 fed from a paper feeder by a charger 6.
is transcribed under the action of After the transfer, the transfer paper is fixed and discharged.

After the transfer, the surface of the photoreceptor drum 1 is cleaned by a cleaning device 7, and the charge is removed up to the charge removal lamp, thus completing one process.

In the case of an ordinary document, a satisfactory image quality can be obtained by the above-mentioned copying operation whether it is a black copy or a color copy, but when a solid image is colored to be copied by the first developing unit 10, toner adhesion is insufficient.

Therefore, when obtaining a color copy of an original having a solid image mode, the copying process is switched by specifying the copying mode using a push button or the like.

That is, for example, normally the photoreceptor drum 1 rotates once for one copying operation, but if a predetermined copying mode is specified, the photoreceptor drum 1 rotates twice during one copying operation, and the photoreceptor drum 1 rotates twice during one copying operation. The operation of each surrounding member can be switched.

For example, as shown in Table 1, the first time is as follows: Charging, erasing, exposure, and development are carried out in the conventional manner.
continues to rotate. The photosensitive drum 1 is then rotated for the second time, and at that time, charging, erasing, and exposing are inactive, but developing, transferring, separating, cleaning, and neutralizing are activated. As a result, the photosensitive drum 1 is developed twice during one copying process, so that the amount of developer attached increases and the developing ability is improved. As a result, the reproducibility of solid images is also improved.

If necessary, only the development can be repeated n times.

As a method of switching the developing time, there is also a method of switching the rotational speed of the photoreceptor drum 1. At this time, it is also necessary to change other conditions during copy machine operation.

Table 2 As an example when using the Se photoreceptor drum 1, in a normal copying mode mainly for lines, the speed of the photoreceptor drum is set to 240/SeC and other conditions are set as shown in Table 2. When copying a solid image in the solid image mode, the speed of the photosensitive drum is reduced to 120 fins/sec, and at the same time, the charging current, exposure amount, transfer current, etc. are changed as shown in Table 2.

By doubling the exposure time in this manner, a good solid image with high image density was obtained.

Although FIG. 1 shows an example in which two developing units are arranged in parallel, the developing device is not limited to this as long as it has a structure that allows color change. For example, as shown in FIG. 2, multiple types of developers can be used. The method for switching the developing time described above can also be applied to a structure in which a developer accommodating section is provided and the developer accommodating section is rotated to switch the activated developer.

In this case, the number of developing devices may be one, or the number of developing devices shown in FIG.
It is also possible for each of the two developing units to have the structure shown in FIG.

In FIG. 2, the developing device 5 includes a developing container 31, a developing sleeve 32 disposed on the left side of the developing container 31 at a position facing the photosensitive drum 1, and a developing sleeve 32 located inside the developing container 31. 32 and a developer storage section 33 arranged at an appropriate interval. The developer sleeve 32 can rotate counterclockwise in the axial view, and has a magnet inside thereof, which is not shown, which is necessary for conveying the developer described later.

The developer storage section 33 includes a plurality of (three in the figure) developer chambers 3.
5B, 35R1, and 35G, and a black component developer 36B, a red component developer 36R1, and a green component developer 36G are stored in each of these chambers, respectively. Further, each developer chamber 35B, 35R135G is individually provided with a replenishment roller 37 as a developer discharge/recovery means.

The supply roller 37 can rotate in both clockwise and counterclockwise directions.

In the illustrated state, the replenishment roller 37 of the black developer chamber 35B faces the developing sleeve 32, but if the replenishment roller 37 rotates counterclockwise in this state, the black developer near the 7117 supply roller 37 The agent 36B mechanically moves counterclockwise following the replenishment roller 37, and as a result, it passes above the replenishment roller 37 and is delivered from the developer chamber 35B to the developing sleeve 32. That is, the developer is discharged. When the replenishment roller 37 rotates counterclockwise and the black developer 1fJI 36B rotates counterclockwise and the black developer 36B is discharged, the replenishment roller 37 is applied with an appropriate voltage having a polarity opposite to the bias voltage of the developing sleeve 32 in advance. is applied, and the discharged developer is charged to a predetermined potential when it passes through a conductive brush or other conductive elastic member 39 that is in contact with the upper part of the supply roller 37.

When the operator wishes to copy another color instead of black copying, for example green copying, he rotates the entire developer storage section 33 clockwise and moves the replenishment roller 37 of the green developing chamber 35G to the developing sleeve. Move it to a position opposite to 32. Thereafter, the green developer 36G is supplied to the developing sleeve 32 to perform the developing operation in the same manner as described above.

- The present invention makes it possible to obtain color copies with good image quality, regardless of the type of image, whether it is a document or other original that has an image mainly composed of lines or a poster or other original that mainly has a solid image. became.

Due to the emphasis on color tone, color toners cannot be freely used with color dyes that control triboelectric charging characteristics, and development conditions are restricted.In addition, the development unit containing the color developer has been made smaller and the structure has been changed to a compact one. However, by changing the conditions related to the photoreceptor drum according to the present invention, it has become possible to improve the image quality despite the above-mentioned restrictions.

[Brief explanation of drawings]

1 and 2 are schematic illustrations of different embodiments of the developing device according to the present invention. 1... Photosensitive drum (electrostatic latent image bearing pair) 5... Developing device Fig. 2

Claims (3)

[Claims] (1) In a copying machine in which multiple developing units containing developers of different colors are arranged in parallel or replaceably adjacent to an electrostatic latent image carrier, depending on the image condition of the original and the type of development. A developing device for a single-color copying machine capable of selecting colors, characterized in that the developing time can be changed depending on the user's needs. (2) The developing device according to claim 1, wherein the speed of the electrostatic latent image bearing band is switchable. (3) The developing device according to claim 1, characterized in that the number of rotations of the electrostatic latent image bearing band in one development step can be changed.