JPH073412Y2 - Development device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a developing device in an electrophotographic apparatus such as a copying machine or a laser printer.

[Conventional technology]

In a conventional electrophotographic apparatus, an electrostatic latent image is formed on a photoconductor by exposure based on a copied image or image data. This electrostatic latent image is developed by the contact of the bristles of the developer formed by the magnet roller and the adhesion of the toner depending on the charged state.

[Problems to be solved by the invention]

However, in the above-described conventional developing device, when the power supply is cut off during the development, the rotation of the sleeve is stopped with the spikes of the developer being formed. That is, the spikes of the developer come into contact with the photoconductor for a long time, and a large amount of toner adheres to the photoconductor.

As a result, the image quality is extremely deteriorated. Moreover, for example, in the case of a color copier having a plurality of developing units that store toners of different colors,
When a portion of the photoconductor to which a large amount of toner adheres moves to the position of another developing unit, the toner attached to the photoconductor may mix into the toner of the developing unit, resulting in color mixing. There was also a problem.

[Means for solving problems]

In order to solve the above problems, the developing device according to the present invention includes a sleeve that is rotatably fitted around the outer circumference of a cylindrical magnet, and causes the developer to have a spike shape to form an electrostatic latent image. In a developing device having a developing magnet roller that contacts the photosensitive member and a shutter that restricts the supply of the developer to the developing magnet roller, a power cutoff that detects that the power supply is cut off during development Detection means,
When the power cutoff detecting unit detects that the power supply is cut off, the shutter control unit that closes the shutter and, after the shutter is closed by the shutter control unit, until the spike of the developer is not formed. Magnet roller control means for rotating the sleeve of the magnet roller, and power supply for supplying power to the shutter control means and magnet roller control means when the power cutoff detection means detects that power supply has been cut off. And means are provided.

[Action]

With the above configuration, if the power supply is cut off during development,
First, the power cutoff detection means detects this, and the power supply means operates to supply power to the shutter control means and the magnet roller control means. On the other hand, the shutter control means closes the shutter so that the developer is not supplied to the developing magnet roller. Also, the magnet roller control means keeps the sleeve of the developing magnet roller rotating.

Then, as the sleeve rotates, the developer that has formed the spikes is removed from the vicinity of the photoconductor, but the developer is not supplied to the developing magnet roller because the shutter is closed. The ears of the rice disappear.

Therefore, even if the power supply is cut off during development, the spikes of the developer do not come into contact with the photoconductor for a long time, so that an excessive amount of toner does not adhere to the photoconductor. . Therefore, in addition to preventing the deterioration of the image quality, in the case where a plurality of developing parts are provided, such as a color copying machine, the toner adhering to the photoconductor is mixed into the toner of other developing parts. Color mixing is also prevented.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4. As shown in FIG. 2, an original placing glass table 1 is arranged on the upper surface of a full-color copying machine so as to be movable in the left-right direction in the figure. Further, a light source 2 for illuminating an original document (not shown) placed on the original placing glass table 1 is provided in the upper part of the copying machine. The reflected light from the original document passes through a plurality of mirrors 3 ... 3 and enters a color separation filter 4, where color separation is performed, and then, through a lens 5 and mirrors 3 and 3, yellow, magenta, and cyan. The component light of each of the three primary colors is sequentially exposed to the belt-shaped photoconductor 6.

The photoconductor 6 is charged to a predetermined potential by a charging charger 7 serving as a charging device, and different regions on the photoconductor 6 are sequentially exposed to the component light of each of the above-mentioned yellow, magenta, and cyan colors, and each region is exposed. An electrostatic latent image for each color is formed in the area. Above the photoconductor 6,
A developing device 8 having four developing units 8a to 8d for developing each of yellow, magenta, cyan, and black is arranged. Then, as the photoconductor 6 travels in the direction A, the electrostatic latent images of the respective colors are sequentially developed by the developing units 8a to 8d having the toners of the corresponding colors. After that, the developed toner image for each color is transferred to the transfer belt by the transfer charger 10.
It is designed to be overlaid and transferred on 11.

The transfer belt 11 has a manual paper feed unit 12 or a paper feed cassette.
Copy paper (not shown) is supplied from 13 and 14, and the transfer belt
11 The toner image in the superimposed state on the transfer charger 15
Is transferred to the above copy paper. The copy sheet onto which the toner image has been transferred is separated from the transfer belt 11 by the separation charger 16 and sent to the fixing device 18 by the conveyor belt 17, where the toner image is fixed on the copy sheet, and then the sheet discharge tray 20. It is designed to be discharged to.

The developing device 8 will be described below. As shown in FIG. 3, each of the developing sections 8a to 8d of the developing device 8 is provided with a developing tank 21, and at the bottom of the developing tank 21, a non-circular magnet 22 having a main pole of the N pole is provided on the outer circumference. A developing magnet roller 24, in which a sleeve 23 made of aluminum, which is a magnetic material, is rotatably fitted at a predetermined interval, is arranged to face the photoconductor 6. The developing magnet roller 24 forms a spike of developer composed of toner and carrier of a predetermined color different for each of the developing portions 8a to 8d as the sleeve 23 rotates, and contacts the photoreceptor. The toner in the developer is supplied onto the photoconductor 6 and the electrostatic latent image corresponding to the color of the toner on the photoconductor 6 is developed.

Like the developing magnet roller 24, above the developing magnet roller 24, a sleeve 26 made of aluminum, which is a non-magnetic material, is rotatably fitted to the outer periphery of the magnet 25 at predetermined intervals so as to be conveyed. For magnet roller 27
Are arranged. The carrying magnet roller 27 carries the developed developer sent from the developing magnet roller 24 to the side of the first stirring roller 28 described later as the sleeve 26 rotates.

First and second stirring rollers 28 and 29 are rotatably arranged respectively above and below the conveying magnet roller 27. The first stirring roller 28 is a toner box described later.
The toner supplied from 35 to the developing tank 21 and the developer in the developing tank 21 are stirred and mixed, and the second stirring roller 29 is further configured to further stir the developer.

A cylindrical shutter 30 is rotatably arranged on the outer circumference of the second stirring roller 29, and openings 30a, 30a are formed at two positions in the circumferential direction of the shutter 30. A partition member 31 is provided between the transport magnet roller 27 and the second stirring roller 29. The shutter 30 is the developing unit shown in FIG.
In the closed state where the openings 30a and 30a face the developing tank 21 and the partition member 31 as in 8a, both stirring rollers 28 and
29 and second agitating roller 29 and developing magnet roller
While the flow of the developer between 24 is blocked and the supply of the developer to the developing magnet roller 24 is restricted, the developing unit of FIG.
As in 8b, the openings 30a and 30a have the first stirring roller.
In the open state facing the developing roller 28 and the developing magnet roller 24, the developer is allowed to flow between the agitating rollers 28 and 29 and between the second agitating roller 29 and the developing magnet roller 24. There is.

As shown in FIG. 1, the shutter 30 is connected with a shutter control means 41 including a microcomputer for closing the shutter 30 when the power supply is cut off. Further, when the power supply to the developing magnet roller 24 is cut off, a microcomputer for rotating the sleeve 23 of the developing magnet roller 24 until the spike of the developer is not formed after the shutter 30 is closed. The magnet roller control means 42 having the above is connected.

Further, when power supply is cut off, shutter control means
An electric power supply means 43 for supplying electric power to the developing magnet roller 24 and the developing magnet roller 24 is connected to a main power relay 44 which is an electric power interruption detecting means for detecting the interruption of the electric power supply. The main power relay 44 is connected to the power supply line.

The shutter control means 41, the magnet roller control means 4
2, the power supply means 43, and the main power relay 44 constitute power cutoff control means 45.

On the other hand, the second stirring roller 29 and the developing magnet roller 24
A toner sensor 32 for detecting the concentration of toner in the developer in the developing tank 21 is attached to the developing tank 21 in the interval. The developing tank 21 below the toner sensor 32 is provided with a doctor 33 for controlling the amount of toner supplied to the photoconductor 6.

A toner box 35 having a toner mixing shaft 34 therein is arranged above the developing tank 21. The toner box 35 is configured to replenish toner into the developing tank 21 by the toner replenishing roller 36 when the toner sensor 32 detects that the toner concentration in the developer in the developing tank 21 is less than or equal to a predetermined value. ing.

In the developing device 8 described above, the developing section 8a in which development is performed
8d, the shutter 30 is used as in the developing unit 8b in FIG.
Is opened, the developer is sent from the second agitating roller 29 to the developing magnet roller 24, and the toner in the developer is supplied to the photoconductor 6.

On the other hand, in the developing units 8a to 8d in which the development is not performed, the shutter 30 is closed like the developing unit 8a in FIG. 3, and the second stirring roller 29 to the developing magnet roller 24 are used.
The supply of the developer to the developing magnet roller 24 is stopped, and the developer remaining on the developing magnet roller 24 is collected by the carrying magnet roller 27 in the peripheral portion of the first stirring roller 28.

By the way, as described above, when the developing unit 8a to 8d is performing the developing process, the power-off control means 45 prepares for the time when the power supply is interrupted, as shown in FIG. Is being processed.

First, it is checked whether or not the main power relay 44 is off (S1). If it is not in the OFF state, the power is being supplied, so the process proceeds to S2, the development is continued, and the process returns to S1. On the other hand, the main power relay 44 is OF
If it is in the F state, it means that the power supply has been cut off, and the process proceeds to S3.

In S3, first, the power supply means 43 is operated to supply power to the shutter control means 41 and the magnet roller control means 42. As a result, the shutter 30 starts to close, while the sleeve 23 of the developing magnet roller 24 continues to rotate.

Next, it is checked whether or not the shutter 30 is closed (S4), and if it is not closed, the process proceeds to S5 to continue the operation of closing the shutter 30 and the rotation of the sleeve 23. If it is determined in S4 that the shutter 30 is in the closed state, the process proceeds to S6, and the operation of the power supply means 43, the closing operation of the shutter 30, and the rotation of the sleeve 23 are stopped.

In this way, even if the power supply is cut off during development, the sleeve 23 continues to rotate and the shutter 30 closes, so that the developer ears formed near the photoconductor 6 on the developing magnet roller 24. The standing disappears. therefore,
Since the spikes of the developer do not come into contact with the photoconductor 6 for a long time, an unnecessarily large amount of toner does not adhere to the photoconductor 6. Therefore, the deterioration of the image quality can be prevented, and in the case where a plurality of developing units 8a to 8d are provided, for example, in a color copying machine, the toner adhered to the photoconductor 6 is not transferred to other developing units 8a to 8d. It is also possible to prevent color mixing due to mixing in the 8d toner.

When the power supply is restored, first, the shutter
After opening 30 to rotate the sleeve 23 of the magnet roller 24 to form the spikes of the developer, the driving of the photoconductor 6 is started and the development is restarted, so that the normal developing operation can be performed. it can.

Although the developing device of a full-color copying machine has been described in the above embodiment, the present invention can be applied to a developing device in various electrophotographic apparatuses, a developing device having a plurality of developing parts, and the like. It is possible.

[Effect of device]

As described above, the developing device according to the present invention is provided with the sleeve rotatably fitted around the outer periphery of the cylindrical magnet, and causes the developer to form the spikes to contact the photoreceptor on which the electrostatic latent image is formed. In a developing device having a developing magnet roller for controlling and a shutter for restricting the supply of the developer to the developing magnet roller, a power interruption detecting means for detecting interruption of power supply during development, and When the power interruption detecting means detects that the power supply is cut off, the shutter control means for closing the shutter, and the magnet after the shutter is closed by the shutter control means until the spike of the developer is not formed. When the supply of power is detected to be cut off by the magnet roller control means for rotating the sleeve of the roller and the power cutoff detection means, the shutter control is performed. Means, and a configuration in which a power supply means for supplying electric power to the magnet roller control means.

As a result, even if the power supply is cut off during development, the ears of the developer immediately disappear, and the developer does not come into contact with the photoconductor for a long time. It will not adhere. Therefore, it is possible to prevent the deterioration of image quality, and in the case where a plurality of developing units are provided, such as a color copying machine, the toner adhering to the photoconductor is mixed into the toner of other developing units. The effect that it is possible to prevent color mixture due to such a situation is exerted.

[Brief description of drawings]

1 to 4 show an embodiment of the present invention. FIG. 1 is a block diagram showing the construction of a developing device, and FIG.
FIG. 4 is a sectional front view showing the structure of a full-color copying machine equipped with a developing device, FIG. 3 is a sectional front view showing the detailed structure of the developing section, and FIG. 4 shows the processing performed by the power-off control means. It is a flowchart. 6 is a photoreceptor, 8 is a developing device, 22 is a magnet, 23 is a sleeve, 24 is a developing magnet roller, 30 is a shutter, 41
Is a shutter control means, 42 is a magnet roller control means,
43 is a power supply means and 44 is a main power relay (power cutoff detection means).

Claims (1)

[Scope of utility model registration request] 1. A developing magnet roller provided with a sleeve rotatably fitted around the outer circumference of a cylindrical magnet, for causing a developer to form a spike and contacting the photosensitive member on which an electrostatic latent image is formed, and a developing roller. In a developing device having a shutter for restricting the supply of the developer to the magnet roller for power supply, the power cutoff detecting means for detecting cutoff of the power supply during the development, and the power cutoff detecting means for supplying the power. When the disconnection is detected, the shutter control means for closing the shutter, and the magnet roller control for rotating the sleeve of the magnet roller until the spike of the developer is not formed after the shutter is closed by the shutter control means. Means and the power cutoff detecting means detects that the power supply is cut off, the shutter control means, and the magnet. Developing apparatus is characterized in that a power supply means for supplying power to over La controller.