JPS6114666A - Automatic toner replenishing device of liquid developing device - Google Patents

Abstract

PURPOSE:To make a Venturi tube unnecessary, and to simplify laying of a pipeline by providing a means for detecting a density of a developer, and a means for making the developer circulate by a pump and opening and closing a valve by a density detector. CONSTITUTION:A recording paper on which a latent image is formed by an electrostatic head reaches on a developing device 12, and a developer 14a flows into a developing slit 20 of the developing device 12 by an operation of a pump 13. On the other hand, an excessive developer ahdering to the recording paper is collected by a squeezing slit 21b and returned to a tank 14. When a density of the developer 14a is lowered as a result of use of many hours, the density of the developer passing through a partially transparent suction pipe 17 is detected by a density detector 18, and at the time of a low density, a solenoid valve 16 is opened and a concenterated toner 15a is replenished to the tank 14. Accordingly, drawing of a pipeline can be simplified without using a Venturi tube.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an automatic toner replenishing device for a liquid developing device.

Structure of the conventional example and its problems A conventional liquid developing device [shown in FIG. 1 - #1. In other words, the Oshiage is connected to the pump 2, and the 111. Liquid retention 3a
is pushed into the developer tank 1 through the pipe 10 with 1 to 1-1 Gero L: The sea urchin consists of Jt F, · S, this, I: The sea urchin is pushed (71 GERA L+ is filled with the developer tank 1 fr, I, The le developer 3a visualizes the electrostatic latent image on the recording paper 81.

Pipe 1o and pipe 11 through which the developer 3a is pushed up
The pipe 11a is branched by a pipe 11a, and a concentration detector 4 is disposed on this pipe 11a. Therefore, during the development described in "=", the developer 3a similarly flows into the pipe 11a, and its concentration is detected. The pipe 11a is a venturi tube 6. Valve 7. It is connected to a toner replenishing device constituted by a pipe 9, and the pliers are driven by the pressure of the developer 3a flowing through the pipe 11a.

A negative pressure is generated in the pipe 6, and the pipe 9 is made into a negative pressure.

The other end of the pipe 9 is a condensed toner.
Rated toner 1 or less is called contoner.

) 6 which, when valve 7 is closed, is immersed in pipe 9. The developer tank 3 is replenished through the bench, the tube 6 and the pipe 11b.The concentration detector 4 and the well 7 are connected to the concentration control circuit 26a, and the developer 3a passing through the pipe 11a is 1+l. [When the concentration detector 4 detects that a certain concentration has been reached 17, the concentration control circuit 26a is activated and the valve 7 is opened.
As outside air flows into the area, the supply of Conktoner 6 will stop.

However, in the automatic toner replenishing device of such a conventional liquid developing device, the negative FF for guiding the condenser 6 is
In order to generate +11 output πI1 of push-up pump 2
Since the structure is such that a venturi tube 5 is connected in parallel to 1 and 1 and 2 negative pressure is generated by the flow of the discharged developing liquid 3a, there is a problem that the negative pressure generation efficiency is low. Venturi tube arrangement and pipe 10 are used to generate negative pressure.
．． 11&, 11b, etc., the structure is complicated, the device is large, and it is expensive.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional problems, and does not use a venturi tube, and the piping strainer does not contain filtrate liquid [1 (only a small amount of white 11 + l:) in the tube. IFi
The purpose is to provide one ``C''.

Structure of the Invention The present invention is as follows: 1. In order to heat up the target, a vacuum pump is connected to circulate the developer between the developer tank and the JLl imager. On the pop suction side,
Connect a pipe from the container and attach a valve device to the pipe, and replenish the concentrated liquid toner from the container to the developer tank by the pressure reducing action of the pressure reducing pump. The gist of this is that we have done so. Since negative pressure is generated on the suction side of the pressure reducing pump during pump operation, there is no need to generate negative pressure using a venturi tube, etc., and the structure can be simplified, allowing efficient suction and replenishment of liquid toner. be able to. However, the valve device uses a solenoid valve, etc., and can smoothly respond to the signal from the concentration detector.

Description of examples The present invention will be described in detail below with reference to the drawings.

6 Page 2 21X ratio 1 This is a configuration diagram of an embodiment of the present invention, and FIGS. 3(a) and 3(b) t:t.
FIG. 2 is a plan view and a perspective view of FIG.

In FIG. 2, the developing device 12 is located at the Jl
, l are connected to a pipe 17 for sucking up the liquid holding liquid 14a. The suction pipe 17 is partially transparent, and a light emitting lamp 18a and a photo sensor 1 are installed near this transparent part.
A concentration detector 18 composed of 8b is arranged.

As shown in FIGS. 3(a) and ('b), the developing device 12 is
Developing slit 20. Squeeze slit 21a.

21b, and one side of the developing slit 20 (the left hand side in the figure) is connected to the suction pipe 17. The other of the slits 20.21a and 21b (on the right-hand side in the figure) is integrally connected 11 to a pipe 24 for recovering the developer.

In FIG. 3(b), 23 is an electrostatic head that forms an electrostatic latent image on the electrostatic recording paper 19. In FIG.

Returning to Figure 2, the recovery pipe 24 is equipped with a vacuum pump (P).
13 is arranged [I], and the developing device 1 is
The developer 7 (V14a) is sucked from 2 to 14 (Jl3).

Collection pipe 24 and 1 vibe 22, 1 minute - 1.
The other end r of the pipe 22 is also immersed in a static toner, that is, a condenser 16a. 16 is a container for storing the compactor 158. A solenoid valve 16 is disposed in the pipe 22, and the operation of the solenoid valve 16 is controlled by a concentration control circuit 26b linked to a concentration detector 18, as will be described later.

To explain the operation of the embodiment of the above configuration, the third
After forming an electrostatic latent image on the electrostatic recording paper 19 by the electrostatic head 23 as shown in FIG. reach the top.

At this time, the pressure reduction pump 13 operates, and the pressure inside the developing device 12 is reduced. Therefore, the developer 14a is transferred to the suction pipe 17.
The developer is sucked up from the developer tank 14 through the developer tank 12.
reach.

Squeeze surino 1-21 a, 21 of developing device 12
As described above, unlike the developing slit 2o, the developing slit 7b is connected only to the Ul+- pump 13 and is not connected to the suction pipe 17. Therefore, the developer 14a is not Rrr in the squeeze slits 7) 21a and 2Ib, but instead is in a reduced pressure state due to the operation of the vacuum pump 13. The excess developer adhering to the electrostatic recording paper 19 that has reached the squeeze slit 21b is removed from the electrostatic recording paper 19 by the inflowing air flow from the contact surface between the developing device 12 and the electrostatic recording paper 19. It is separated, collected in the squeeze slit 21b, and after passing through the vacuum pump 13, the developer tank 14
Return to On the other hand, the electrostatic recording paper 19 is developed and fixed by a subsequent fixing device (not shown).

When continuous recording and long-term recording are performed here, the density of the developer in the developer tank 14 decreases because toner particles are consumed.

The concentration detector 18 detects the concentration of the developer 14a sucked up through the suction pipe 17 and directed toward the developing device 12. Here, the developer 14a flowing through the suction pipe 17 is illuminated with a light-emitting lamp 18a, and when the transmission exceeds the reference level 1r1.1, the solenoid valve 16 is opened by the control circuit 261). .

That is, when the electrostatic recording paper 19 is placed in the developing device 12F, the vacuum pump 13 is activated and the developer 14a begins to circulate, and the density detector 18 starts measuring the negative action L and the amount of transmitted light. If the amount of transmitted light is large, it is determined that the concentration is lower than the reference concentration, and a signal is given to open the solenoid valve 16. pipe 22
Since the pressure is reduced by the vacuum pump 13, the condensate toner 16a is sucked up and replenished from the toner container 16 into the developer tank 14. Developer solution 1 in developer tank 14
When the concentration of 4a suddenly reaches the reference concentration, the concentration detector 18 controls the solenoid valve 16 to close.

This completes the supply of toner 15a.

In reality, it is possible to implement the operation method described above, but
If the pipe distance from the solenoid valve 16 to the developer tank 14 is long, or if the condenser 1 is
5a may be sufficiently stirred and the concentration detected by the concentration detector 18, and the electromagnetic valve 16 may be refilled with an extra 9 bases.

However, it is fine when the developer tank 14 is not sufficiently filled with the developer solution 14a, but if the developer solution 14a becomes a little low, the condenser replenishment area increases. Therefore, in such a case, the concentration detector 18 does not always perform concentration control, but performs sampling at a certain appropriate time interval, and controls the opening time of the solenoid valve 16 when the concentration falls below the reference value. Replenishment will be effective.

FIG. 4 is a block diagram of the density control circuit 26b, which can be used in place of the density control circuit 26a in FIG. In the figure, 18a is a light emitting lamp, 26 is a lamp lighting circuit, 18b is a photosensor, and 27 is photosensor 1.
8b is an amplifier circuit for amplifying the output voltage; 28 is a sampling circuit that samples the output voltage of the photosensor 18b according to a signal from the timing generation circuit 3o;
Reference numeral 29 denotes a comparison circuit for comparing the output of the sampling circuit 28 with a reference voltage, and a solenoid valve control circuit for opening and closing the solenoid valve 16 in accordance with the signal ``i810'' from the 31-digit comparison circuit.

The operation of the density control circuit 26b configured as described above will be explained using the timing chart shown in FIG.

The timing generating circuit 3o generates two timing signals shown in FIG. 6A and B. A is a first timing signal for detecting toner concentration, and changes in toner concentration are monitored every cycle T1. Using the rise of the signal A as a trigger, a second timing signal with a period T2 indicated by B opens and closes the electromagnetic valve 16 to control the toner concentration.

Control of toner density will be explained in more detail. FIG. 6C shows the second timing signal B in an enlarged manner for ease of explanation. D in FIG. 6 is the output voltage waveform of the photosensor 18b. When the toner density is low, the output voltage is high, and when the toner density is high, the output voltage is low. This output voltage is amplified by the amplifier circuit 27 and then sampled by the sampling circuit 28 at a period T2, resulting in the waveform shown in FIG. 6E.
The 11 is outputted by the page sampling circuit 28. This output signal E
is sent to the comparator circuit 29 and compared with the reference voltage indicated by the broken line in FIG. 6H. The input voltage of the comparison circuit 29 is the reference voltage H
When the value is higher than , the output of the comparison circuit 29 becomes high level, and becomes a control signal for the electromagnetic valve control circuit 31 indicated by F in FIG. The solenoid valve control circuit 31 detects the fall of the control signal shown in FIG.
The signal G is sent out.

Therefore, the condensation toner 15a is supplied from the condensation container 15 to the developer tank 14 through the developer circulation system only during the time T3. If the toner concentration does not reach the desired concentration by the first sampling of the second timing signal B, the solenoid valve is further opened for T3 during the second sampling of the second timing signal B, and the toner concentration is increased by the second sampling of the second timing signal B. Replenish 16a. In this way, the electromagnetic valve 16 is opened to reduce the amount of condensation toner to be replenished at one time, and the concentration is detected many times with small amounts to replenish the condensation toner 15a. Therefore, it is possible to prevent the developing solution 14a in the tank 14 from becoming low and a large amount of condensation toner to be replenished, thereby preventing image fogging from occurring.

Effects of the Invention According to the present invention, since the depressurizing action of a vacuum pump is used, there is no need to specifically arrange a Venturi tube as in the conventional case, and the piping thereof is also very simple.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional liquid developing device, Fig. 2 is a block diagram of an embodiment of the present invention, Fig. 3 (-) is a plan view of the developing device in Fig. 2, and Fig. 3 (b) 4 is a block diagram of the density control circuit, and FIG. 6 is a timing chart of the density control circuit shown in FIG. 4. 12...Developer, 13...Reducing pressure pump %14...Developer tank, 15...(conc) toner container, 16... Solenoid valve (valve device)
, 17... Suction pipe, 18... Concentration detector, 22... Pipe, 26a. 26b...Concentration control circuit. Name of agent: Patent attorney Toshio Nakao and one other person
Chihe \

Claims (1)

[Claims] a developer tank for storing a developer, a developer, a vacuum pump for circulating the developer between the developer tank and the developer, and a concentration detector for detecting the concentration of the developer; A toner container storing concentrated liquid toner, a pipe connected between the toner container and the suction side of the pressure reducing pump, and a valve device provided on the pipe and opened and closed by the output of the concentration detector. An automatic toner replenishing device for a liquid developing device, characterized in that the liquid toner in the toner container is replenished into the developer tank by the decompression action of the decompression pump.