JPS60136777A - Developing device of copying machine - Google Patents

Abstract

PURPOSE:To prevent toner from causing ground staining, stripe staining, etc., in an image plane by providing a developing sleeve opposite a photosensitive body and an upper scooping roller and a magnet roller which are arranged below the developing sleeve successively. CONSTITUTION:The developing device 2 consists of a casing 3 which contains a developer, the magnet roller 4 for stirring which is arranged near the bottom in the casing 3, a lower scooping roller 5 which is arranged a little bit above the magnet roller 4, the upper scooping roller 6 which is arranged a little bit above the lower scooping roller 6, and the developing sleeve 7 which is arranged between the scooping roller 6 and photosensitive drum 1. Consequently, the developer is not scooped up toward the developing sleeve immediately and supplied while the upper scooping roller is not in operation, thereby eliminating the ground staining, stripe staining, etc., of toner in an image plane.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developing device using a two-component developer in an electrophotographic copying device.

In the developing device of the Jubei Ojigai color copying machine, a developing unit that individually accommodates three or four color developers is used.
In each developing unit, there is a magnetic developing device in which developer is attracted to a rotating developing sleeve made of magnetic material by the action of a static 11-magnet inside the developing sleeve, forms brush-like spikes, and develops by contacting the photoreceptor. Commonly used. During color development, if developers of other colors come into contact with the photoreceptor during development of one color, color mixing and image disturbance will occur, so it is necessary to prevent the ears of developing sleeves of other colors from coming into contact with the photoreceptor. . For this reason, a method has been proposed in which a developing unit containing developer of another color is prevented from pumping the developer into the developing sleeve during development.

There is a method of keeping the pigeon house and developing sleeve constantly rotating and setting the pumping roller to 1, but with this method,
Considering the fact that the pumping roller also serves to stir the developer, the agitation of the two-component developer becomes insufficient, and the replenished developer enters the next development operation when the pumping roller starts rotating. There are cases where the amount of charge remains low due to insufficient stirring and is pumped onto the developing sleeve. At this time, background smudges and density fluctuations occur in non-image areas, causing an increase in developer scattering outside the developing unit.

The object of the present invention is to provide a developing device that solves the above-mentioned conventional problems.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention that achieves the object described in item (2) above will be explained based on the embodiments shown in the drawings.

In FIG. 1, a developing device 2 is arranged next to a photosensitive member, for example, a photosensitive drum 1. As shown in FIG. In the case of color copying, for example, when three color developers are used, three developing devices each containing a different color developer are arranged side by side along the photoreceptor 1. Although not shown in the figure, a charging device, an exposure optical device, a transfer device, and the like are arranged along the photosensitive drum 1 in a known manner.

Even when a plurality of developing devices are arranged in a color copying apparatus, the structure of the developing devices is the same except that the developer is different, so one developing device will be explained below. - The developing device 2 includes a casing 3 containing a developer, a stirring mag roller 4 disposed near the bottom of the casing 3, a lower pumping roller 5 disposed slightly below the mag roller 4, and a lower pumping roller 5 disposed slightly below the mag roller 4. It has a pumping roller 6 arranged slightly above the pumping roller 5, and a developing sleeve 7 arranged between the pumping roller 6 and the photosensitive drum 1.

The mag roller 4, the lower pumping roller 5, the upper pumping roller 6, and the developing sleeve 7 each have a nonmagnetic roller and a fixed magnet provided inside the roller.

Each casing 2 is supplied with a developer 9 of a color corresponding to each developing device through a developer toner supply pipe 8. Developers of yellow, magenta, cyan, etc. are supplied and stored in the casing 3 from the replenishment vibrator 9.

The developer remaining in the developing sleeve 7 after the photosensitive drum is developed by the spikes of developer formed on the developing sleeve 7 is guided by a scraper 9 and returned into the casing 3. At this time, the developer concentration sensor 10 detects the concentration. The developer returned by the scraper 9 is removed from the partition plate 14.
A lateral agitation device 11 such as a screw provided in a space separated from the space in which the pumping roller 5.6 is provided performs lateral agitation so that the developer is uniformly distributed without being unevenly accumulated in a part of the casing 3. Do it like this.

When a plurality of developing devices are used in a color copying apparatus, when one developing device performs, for example, yellow development, the other developing devices are in a non-operating state.

In the developing device during the developing operation, the mag roller 4, the lower pumping roller 5, the upper pumping roller 6, and the developing sleeve 7 are all rotationally driven, and the developer 1 in the casing 3 is rotated.
2 is pumped up to the developing sleeve 7. On the other hand, in the conventional developing device when the developing device is in an inactive state, even though the developing sleeve rotates, the pumping roller is stopped and the developer is not pumped up to the developing sleeve.

However, in order to sufficiently agitate the developer, it is necessary that the pumping roller be driven to rotate for as long as possible even in a separate developing device that is in a non-developing state. For this reason, in the present invention, in the non-operating developing device, the developing sleeve 7 and the lower pumping roller 5 are
The mag roller 4 continues to rotate at all times, but the upper pumping roller 6 is stopped and raised.

The operation of the developing device according to the present invention will be explained.

In the developing device involved in development, a mag roller 4, a lower pumping roller 5, an upper pumping roller 6, and a developing sleeve 7 are all driven, and the developer is drawn up onto the surface of the developing sleeve 7 to form spikes. The ears contact the photoreceptor and develop an electrostatic latent image on the photoreceptor.

The developer after development is returned by the scraper 9, passes through the concentration sensor 11, is stirred in a space with a horizontal stirring device 12, and is sent toward the mag roller 4. During this time, if the density sensor 11 detects that the developer is below a predetermined density level, this is stored.

When the developing device is inactive, for example, when another developing device is in operation, the upper pumping roller 6 remains still and stops pumping up the developer to the developing sleeve 7. Therefore, no spikes of developer are formed on the developing sleeve 7. However, since the mag roller 4 and the lower pumping roller 5 continue to rotate, the developer 13
The water circulates between the mag roller 4 and the bottom roller 5 while being agitated. Therefore, the developer 13 can be sufficiently stirred. When a decrease in density is detected during development operation, fresh developer 10 is supplied from replenishment pipe 8 during non-operation.
will be replenished. At this time, it is advantageous to allow the replenishing developer to be fed into the intermediate portion between the mag roller 4 and the bottom scooping roller 5 using the partition plate 14 in order to achieve sufficient agitation. After the replenished developer is sufficiently stirred, it enters the developing state and can be drawn up by the pumping roller 6. Therefore, the amount of charge on the developer shows a sufficient level.

■ The developer replenished by the spike is immediately pumped toward the developing sleeve, so that it is not thrown away, and is replenished while the roller is still pumping, and is sufficiently stirred. It is possible to obtain a sufficient amount of charge, so it does not scatter,
It has become possible to eliminate the occurrence of background smudges, streaks, etc. on the screen.

[Brief explanation of drawings]

The figure is an explanatory diagram of a developing device according to the present invention. 1...Photoconductor 2...Developing device 3...Casing 4...Mag roller 5...Lower pumping roller 6...Upper pumping roller 7...Developing sleeve 8...Developer supply pipe 9...Scraper 11...Concentration sensor 12...Horizontal stirring device

Claims (1)

[Claims] A developing sleeve disposed to face the photoreceptor, a pumping roller and a mag roller disposed sequentially below the developing sleeve, a scraper having one end disposed close to the developing sleeve for guiding the developed agent, and a scraper for guiding the developed agent. A toner concentration sensor and a horizontal agitation device arranged in sequence below the other end, a partition plate separating a space where the horizontal agitation device is installed and a space where a pumping roller is installed, and a space on the side of the pumping roller from the partition plate. In a developing device of a copying machine having a developer replenishing pipe arranged in 1. A developing device for a copying machine, characterized in that the time for reinforcing the developer is set when the first pumping roller is stationary, and the replenishing position is set between the mag roller and the lower pumping roller.