JPS58111069A - Developer concentration control device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] The present invention is applied to a developer concentration control device for a wet-type developing device. The wet-type developing device has a simple structure, high image adjustment quality,
Because of its compactness, it is often used as a developing device for copying machines and printers. Developer concentration control in a wet developing device that uses a two-component developer consisting of toner and dispersion waves is generally l! This is carried out by means for detecting the liquid concentration and toner replenishing means. However, some devices have a means for automatically replenishing a dispersion liquid that does not contain toner or a replenisher liquid with a certain toner concentration, but this is not intended to control the liquid concentration, and is not intended to control the liquid concentration of the developing device. This is to keep the liquid level in the tank constant. In a wet developing device, when a print is taken, both toner and dispersion are consumed by the transfer paper. The amount of toner consumed varies depending on the pattern, but in general patterns, the amount of toner consumed in terms of mixing ratio is greater than that of the dispersion, so the toner concentration in the liquid gradually decreases. This concentration change is sensed by the concentration detecting means, and when the concentration exceeds a certain value, toner is added by the toner replenishing means to increase the concentration of the liquid, and the liquid concentration is controlled to be one level.

However, in addition to consumption by the transfer paper mentioned above, developer consumption includes evaporation from the surface of the latent image forming drum and evaporation from the developing plate or tank. Consumption by transfer paper is both toner and dispersion, while consumption by evaporation is limited to dispersion.

Therefore, it is fine if the amount of toner consumed by the transfer paper is commensurate with the amount of evaporation of the dispersion, but for users who only print a small amount, the amount of F toner consumed is small, and the dispersion is lost by evaporation over time, so the developer A phenomenon occurs in which the toner concentration inside becomes higher. If the toner density is too thick than the set density, not only will interlayers occur in the image quality such as blurring, thickening of characters, and fogging of the background, but there will also be problems such as the toner becoming more likely to settle in the developing tank.

The conventional concentration control device described above has the disadvantage that it cannot prevent this phenomenon because it does not have a means to dilute the concentrated liquid.

Note that some devices are equipped with a mechanism that collects the dispersion that evaporates during fixation on the transfer paper and returns it to the developing device. It is clear that the phenomenon of the developer becoming thicker cannot be prevented.

SUMMARY OF THE INVENTION An object of the present invention is to provide an apparatus which eliminates the drawbacks of the prior art described above and can control the developer concentration to a constant value in any case.

The present invention is a developer concentration control device characterized by having means for increasing the concentration of the developer and means for decreasing the concentration of the developer.

An embodiment of the present invention will be described in detail below with reference to the drawings.

Figures 1 and 2 show an embodiment of the present invention, in which 1 is a developer tank for storing developer 2, 3 is a developer stirring pump, 5 is a developing tray, and 6 is a replenishment tank containing replenishing toner. Toner bottle, 8 is the pulp of the toner bottle 6 for replenishment, 9 is a plunger for opening the pulp 8, 10 is a replenisher bottle containing replenisher (liquid lighter than the developer solution setting concentration) 11, 1 g
C. The pulp of the replenisher bottle 10, 13 is a plunger for opening the pulp 13. Further, 16 is a cell for measuring the concentration of the developer sent from the developer stirring pump 3, 16 is a lamp for concentration measurement, 1 is a light-receiving element for measuring concentration, and 18 is operated by the output from the light-receiving element 1'I. It's an amplifier.

In the above configuration, when the stirring pump S operates, the developer 3
is stirred and a portion is sent to the developing MIS and a portion is sent to the density measurement cell 16. One light receiving element measures the light transmittance of the developer in the density measuring cell 16 illuminated by the lamp 16 and supplies it to the output amplifier 8. Amplifier 18 is light receiving element 1
When it is determined from the output of step 1 that the light transmittance of the developer is higher than the set value, that is, the concentration of the solution is higher than the set concentration, the plunger 9 is pulled to open the pulp 8 and replenish toner from the replenishing toner pot 6. Increase the liquid concentration. Conversely, when the light transmittance of the developer is smaller than the set value,
That is, when it is determined that the liquid concentration is higher than the set concentration, the plunger 13 is pulled to open the pulp 12, thereby replenishing the replenishing liquid 11 from the replenishing liquid bottle 10 and diluting the liquid concentration.

With the above configuration, it is possible to control the concentration to the set concentration not only when the developer concentration becomes low due to printing on transfer paper, but also when the developer concentration becomes high due to evaporation of the dispersion liquid. be.

In the above example, if the replenisher 11 is composed only of a dispersion liquid, it is fine. If it is a mixture of a certain amount of toner and a dispersion liquid (however, the liquid is thinner than the set concentration of the developer), the following method is used. There are some problems.

In other words, in order to dilute the concentration of the fractional liquid that has become thicker due to # release with a replenisher consisting of toner and dispersion liquid to restore the original concentration, a larger amount of replenishment liquid is needed than the amount of dispersion liquid lost due to evaporation. If this situation continues, the liquid level will rise and the developer tank may eventually overflow. In order to prevent this drawback, a mechanism as shown in Fig. 3 should be added. 19 is 70-F for detecting the liquid level position
120 is a wall that guides the float, and al is a switch. When the liquid level rises, 70-) 19 rises, and when the liquid level reaches the set upper limit, the switch 21 is turned on. When the switch 21 is turned on, it causes the amplifier 18 to prohibit further replenishment of toner or replenisher.

With the above configuration, the replenisher or toner is not replenished when the liquid level exceeds a preset upper limit, so overflow of the liquid from the developer tank can be prevented.

Another embodiment in which the volume of the developer is controlled at the same time as the concentration of the developer will be described with reference to FIG.

a2 is a replenisher bottle with two pulps, 8s is a pulp for liquid level control, and 24 is a prize ivy for opening the pulp 23. The pulp 12 detects that the concentration of the liquid is too high, and when diluting it, it is fought by the pufunger 13 to replenish the replenisher.◎The valve 25 is activated when the replenisher bottle 2s is installed in the developer tank 1. 1Iji on the bottom of the tank
i! When the level of the developer 3 is lower than the height of the open end of the bowl, the replenisher 11 is replenished. When the liquid level reaches the height of the first eye end or the height of the opening end due to replenishment, no further replenishment is performed, which is a so-called chicken feed method.

With the above configuration, it is possible to control the liquid concentration by replenishing the replenisher and simultaneously control the height of the liquid level in the developer tank.

As explained above, by performing bidirectional concentration control of toner replenishment and replenishment liquid replenishment according to the present invention, not only when the liquid becomes too thin than the set concentration, but also when the liquid becomes too thick. can now be controlled.

Furthermore, by having a bidirectional concentration control means, it has become possible to control the concentration and at the same time control the volume of the developer.

[Brief explanation of the drawing]

Fig. 1 is a diagram of an embodiment of the concentration control device, Fig. 3Ia is a boot diagram showing the concentration detection method and concentration control method, Fig. 3 is a diagram showing the liquid overflow prevention mechanism, and Fig. 4 is a diagram showing the concentration control at the same time. The figure which showed the modification which performs liquid level position control. 1.--1111 developer tank, 3------1 developer stirring pump, 4----- pump drive motor, 6--
-------- Wing imager, 6----~-m- Refill toner bottle, l O------ Replenisher bottle, 9-------
--→Plunger for replenishing the replenishing liquid, 1 5-----1 plunger for replenishing liquid, 14--1 photosensitive drum. L Yu (

Claims (1)

[Scope of Claims] A developer concentration control device in a wet electrophotographic developing device, comprising means for increasing the concentration of the developer and means for diluting the concentration of the developer. The developer concentration control device according to claim 1, wherein the control is stopped when the liquid level reaches a predetermined upper limit. A developer concentration control device as described in item 1 of the scope of the patent application, characterized in that when the number of one-wave box exceeds a predetermined lower limit, the developer is replenished so that the liquid level does not fall below a certain level. .