JPS62266581A - Developing device - Google Patents

Abstract

PURPOSE:To hold toner density in a developing device at a fixed level by arranging plural toner density detecting means and feeding toner in accordance with toner density values detected by these detecting means. CONSTITUTION:A front side auto-toner detector 7a and a rear side auto-toner detector 7b are arranged and toner ratio density in a developing flow scraped from a developing sleeve 1 is detected by these detectors 7a, 7b. When the toner ratio density on the front side is dropped, a feeding signal is outputted from the detector 7a and the detector 7b is kept at the normal state. A difference between the outputs of the detectors 7a, 7b is detected by a judging circuit and a toner feeding motor 6 is rotated at a low speed by a control circuit. Since the toner is moderately carried in a toner carrying pipe 5, the toner is not almost dropped in a toner dropping hole 5a on the front side, so that the toner ratio density on the front side is returned to the normal level and becomes almost the same as the toner ratio density on the rear side.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Field of Application) The present invention relates to a developing device used in an electronic copying machine, etc., and particularly relates to a developing device that can control the toner replenishment position and replenishment base. Regarding equipment.

(Prior Art) In a conventional developing device, toner is uniformly replenished onto the surface of a developing roll and agitated so that the developer in the developing device has a uniform toner specific concentration.

However, when a recent high-speed electronic copying machine continuously copies a document with a yA degree gradient in the direction perpendicular to the direction of transfer paper, or when an intelligent electronic copying machine continuously performs partial erasing. However, the specific toner density within the current device was often not uniform.

In such an electronic copying machine, there is only one automatic toner that detects the toner density value, and toner replenishment is performed by replenishing the toner uniformly into the developing device main body, so the following problems occur. was.

That is, when a large amount of toner near the automatic toner detection section is consumed by a document portion with high document density, toner replenishment is performed because the toner specific density of the detection section decreases. However, in the developing roller section corresponding to the low-density area of the original, overtoner occurs, causing background fog and
Toner scattering, toner falling, etc. may occur.

On the other hand, if the toner near the automatic toner detection section is not consumed as much as possible because the document is thin, toner replenishment is not performed because the toner specific density at the detection section remains normal. For this reason, only the toner in the dark areas of the document is consumed, resulting in undertoner in these areas, resulting in carrier adhesion, carrier drop, etc.

In addition, when toner is replenished using an auger transport method from the front side, the fluidity of the toner tends to change due to environmental changes, and the position where the toner falls within the developing device changes, causing a concentration gradient in the developer. There were also problems that occurred.

(Problem to be solved by the invention) The conventional current @ device performs toner replenishment uniformly,
There was a problem in that it was not possible to cope with uneven distribution of toner.

The present invention has been made in response to this situation, and an object of the present invention is to provide a developing device that can maintain a constant toner concentration.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a main body including a developing roller that rotates while carrying a developer on its surface in a developing device, and this main body. a toner replenishing means for replenishing toner within the main body; a plurality of toner concentration detecting means provided at different positions within the main body; and a toner concentration detected by the toner concentration detecting means by controlling the replenishing operation of the toner replenishing means. A control means for replenishing toner to an area where the value is low is provided.

(Function) Therefore, the toner concentration of the developing roller placement portion can be accurately detected by the plurality of toner concentration detection means, and appropriate toner replenishment can be performed according to the detected toner concentration value.

(Example) Hereinafter, the present invention will be explained with reference to the drawings.

FIG. 1 is an internal perspective view of one embodiment of the present invention.

This developing device includes a developing sleeve 1 on which a thin film of developer is formed, a doctor blade 2 that scrapes off the developer on the developing sleeve 1, and a toner supply port 3 to which toner is supplied from a toner hopper (not shown). A toner transport auger 4 and a toner transport pipe 5 that transport toner from the toner replenishment port 3 into the developing device body, a toner replenishment motor 6 that rotates the toner transport auger 4, a doctor blade 2 and a toner transport pipe 5, Front side auto toner 7a and rear side auto toner 7b provided between
The toner specific concentration in the developer flow scraped off from the developing sleeve 1 is detected by the auto-toner 7. Further, the toner conveying pipe 5 is provided with toner drop holes 5a, . . . as shown in FIG. 2, and toner is replenished into the developing device main body through the toner drop holes 5a, .

FIG. 3 is a block diagram showing the configuration of the control section of this developing device.

This control section includes a determination circuit 8 that determines the amount of toner to be replenished and the replenishment position in response to toner replenishment signals from the auto-toners 7a and 7b, and a determination circuit 8 that determines the amount of toner to be replenished and the replenishment position in response to toner replenishment signals from the auto-toners 7a and 7b, and a determination circuit 8 that determines the toner replenishment position and the amount of toner to be replenished according to toner replenishment signals from the auto-toners 7a and 7b, and a toner replenishment controller 6 that determines the amount of toner to be replenished and the replenishment position according to the output from the determination circuit 8. It is composed of a control circuit 9 that controls the rotation speed.

Next, the operation of the developing device in an electronic copying machine using this developing device will be explained.

First, when the toner specific density on the front side decreases, a replenishment signal is output from the auto toner 7a, and the auto toner 7a to toner 7b remain normal. This auto toner 7a, 7
The determination circuit 8 detects the difference in the output of the toner replenishing motor 6, and the control circuit 9 causes the toner replenishment motor 6 to rotate at a low speed. Then, the toner conveyed from the toner replenishing port 3 by the toner conveying auger 4 is slowly conveyed through the toner conveying vibrator 5, so that most of it falls at the toner drop hole 5a on the front side, and the toner from 1 to 4 on the front side is concentration returns to normal,
The specific density of toner on the rear side is the same.

Similarly, when replenishing both the front and rear sides, that is, when replenishing the entire surface, rotate the toner transport auger 4 at medium speed, and when replenishing only the rear side, rotate the toner transport auger 4 at high speed. By rotating, toner supply is controlled.

FIG. 4 is a perspective view of a toner conveying pipe 5 in another embodiment of the present invention.

In this embodiment, toner drop holes 5a, .

According to this embodiment, the toner conveying auger 4 is rotated at a constant rotation speed, and by rotating the toner conveying pipe 5 and changing the position of the toner drop hole 5a, toner is replenished to the front side and the rear side, respectively. be able to.

Further, when replenishing the entire surface of the developing sleeve with toner, the toner conveying pipe 5 is rotated at a constant speed to replenish the toner evenly to the front side and the rear side.

In the above embodiment, the 1-toner ratio was detected at multiple locations in the developing device and the toner was controlled to be replenished to areas with low toner specific density, so the toner specific density in the developing device was always maintained. It becomes uniform.

Therefore, in electronic copying machines using these embodiments, even if originals with large density gradients are continuously copied, there is no toner specific density gradient of the developer, and partial background fogging, density changes, carrier adhesion, etc. can be avoided. It can be prevented.

In addition, in the intelligent electronic copying machine using these embodiments, the Q of the toner ratio kilK due to partial erasure etc.
II gradient can also be prevented.

Furthermore, in these embodiments, toner is replenished by an auger conveyance method from the front side, but it is also possible to prevent the occurrence of a toner specific concentration gradient of the developer due to changes in toner fluidity caused by environmental changes. .

[Effects of the Invention] As explained above, according to the present invention, a plurality of toner concentration detection means are arranged and toner replenishment is performed directly in accordance with the detected toner concentration, so that the toner concentration in the device can be kept constant. can be kept.

[Brief explanation of drawings]

FIG. 1 is an internal perspective view of an embodiment of the present invention, FIG. 2 is a front view of a toner conveying pipe in the embodiment, FIG. 3 is a block diagram showing the configuration of a control section in the embodiment, and FIG. 4 FIG. 3 is a perspective view of a toner conveying pipe in another embodiment of the present invention. 1...Developing sleeve 4...Toner transport auger 5...
...Toner conveying pipe 7 ...Auto toner applicant Toshiba Corporation Patent attorney Suyama Sa - Yan 1 Figure 2

Claims (2)

[Claims] (1) A main body equipped with a rotating developing roller carrying developer on its surface, a toner replenishing means for replenishing toner into the main body, and a plurality of toner concentration detecting means provided at different positions within the main body. 2. A developing device comprising: a control means for controlling the replenishment operation of the toner replenishing means to replenish toner to a portion where the toner concentration value detected by the toner concentration detection means is low. (2) The toner replenishing means is composed of a toner conveying pipe having a plurality of toner drop holes and a toner conveying auger,
2. The developing device according to claim 1, wherein the toner replenishment operation is performed by rotating the toner transport auger, and the control means adjusts the toner replenishment position by controlling the rotational speed of the toner transport auger.