JPS6289082A - Abnormality detecting device for liquid developing device - Google Patents

Abstract

PURPOSE:To judge abnormality such as jamming, deficiency of premixed liquid etc. by judging a signal from a means that detects pressure of a suction system connected to a means that detects pressure of a developer circulating system and a squeezing device by an abnormality judging circuit. CONSTITUTION:When a vacuum switch 12 became from OFF to ON within 0.5sec and a solenoid valve 9 is opened, concentrated toner in a concentrated toner container 10 is deficient, and this is indicated. In case the vacuum switch 12 continues OFF state for more than 0.5sec, a vacuum pump 14 connected to a squeezing device 3 is operated to operate the device 3. When the vacuum switch is ON, jamming is not caused and liquid in a premix tank 7 is deficient, and accordingly, this is indicated. When the vacuum switch became OFF, an electrostatic recording paper 4 is separated from the slit 13 of the device 3. Accordingly, jamming is caused in this case. Therefore, jamming is indicated and the device is stopped immediately.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a device for detecting abnormalities such as jam detection and liquid developer shortage display in a liquid developing device such as a facsimile machine.

2. Description of the Related Art Conventionally, this type of device uses a vacuum switch to detect jams, as seen in Japanese Utility Model Publication No. 52-25153.
There is a device that is placed in a part of the developer circulation system of a developing device, and when a jam occurs, the vacuum in the circulation system drops, and this is detected by a total vacuum switch to detect all abnormalities. However, with this method, even if the developer tank in the developer circulation system runs out of liquid, the degree of vacuum in the circulation system will drop, and the vacuum switch will detect this and display a jam display. It has the following drawbacks. In order to prevent this malfunction, the liquid level in the tank was usually monitored using a total capacitance sensor.

Further, as shown in FIG. 4, a condenser container 105 is connected via a solenoid valve 108 to a developer circulation system consisting of a developer 100, a vacuum pump 101, and a premix tank 103 containing a developer of a predetermined concentration. and a premix tank 103 and a developing device 1o.

There is also known a device in which the concentration of the premix liquid is detected by a concentration meter 107 placed in the piping between the premix liquid and the concentration meter 107, and when the concentration becomes lower than a reference value, the condensation liquid is replenished from the condensation container 105 into the circulation system. There is.

In this device as well, a vacuum switch 102 is provided in the developer circulation system to detect a jam.
3 and the liquid in the condenser container 106, the vacuum switch 102 is activated.
In order to prevent malfunctions due to causes other than jams, electrostatic 8-type sensors 104 and 106 are arranged in both the premix tank 103 and the condenser container 105, respectively.

Problems to be Solved by the Invention However, with this configuration, the capacitance type sensor is expensive, and in the case of a color recording device, four developing units for cyan, magenta, yellow, and black are required. As a result, the number of capacitive sensors increases accordingly, resulting in a further increase in cost.

The present invention has been made in view of the above-mentioned problems, and eliminates the need for providing liquid level detection means such as capacitance type sensors in the premix tank and the condenser container, respectively, and increases the equipment cost. It is an object of the present invention to provide an abnormality detection device that can identify and detect abnormalities such as jam, lack of premix liquid, and lack of condenser without causing problems.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a developing device that completely applies a liquid developer by contacting a recording medium that is running, a pump, a liquid developer tank, and a liquid developer tank. a first pressure detection means arranged in a developer circulation system; a second pressure detection means arranged in a suction system connected to a squeeze device that contacts a running recording medium and sucks up excess liquid developer; an abnormality detection circuit for detecting an abnormality based on the signals of the first pressure detection means and the second pressure detection means, the abnormality detection circuit comprising:
a first determining means for determining whether or not the abnormality detection signal from the first pressure detecting means continues for a predetermined period of time or more; a means for operating the squeezing device in response to the signal from the first determining means; The second pressure detecting means has a second determining means for determining whether the signal from the second pressure detecting means is normal or not.

Operation In the present invention, with the above-described configuration, the first pressure detection means detects a pressure change in the developer circulation system to detect an abnormality. This abnormality occurs due to a jam in the recording medium, a lack of liquid in the liquid developer tank, or a lack of liquid in the compactor container. Determine whether it will continue for a long time,
specify a reason. That is, if the abnormal signal is short-lived, it is caused by a lack of liquid in the condenser container when the condenser is supplied from the condenser container to the developer circulation system. On the other hand, if the abnormal signal continues for a long time, the cause is a jam or a lack of liquid in the liquid developer tank. In the latter case, the squeezing device is further operated, and the second determining device judges the signal from the second pressure detecting device connected to the squeezing device. If the signal is normal, no jam has occurred, and the liquid developer is The cause is a lack of liquid in the tank, and if there is an abnormality, it is determined that the cause is a jam. In this way, abnormalities can be detected and their causes determined.

EXAMPLES The present invention will be explained in further detail below with reference to all the examples shown in FIGS. 1 to 3.

Figure 2 shows the principle of recording a color image using electrostatic recording, in which 1 is an electrostatic head, 2 is a liquid toner of four colors cyan, magenta, yellow, and black supplied. 3 is a squeeze device, 4 is a roll of electrostatic recording paper, and 5 is a drive roller. When conveyance of the electrostatic recording paper 4 is started by the drive roller 5, a voltage is applied to the electrostatic head 1, and the electrostatic recording paper 4 is moved to y where an electrostatic latent image is formed on the electrostatic recording paper 4. is conveyed, and in order to develop it into the appropriate color, a developing device of the required color (in the illustrated embodiment, developing device 2 & supplied with black toner) is brought into contact with the electrostatic recording paper 4 to develop and produce a visible image. become When the development for one sheet is completed, the developing device lowers,
Move away from the electrostatic recording paper 4. The electrostatic recording paper 4 is further conveyed, and the squeeze device 3 wipes off the wetness that occurs when the developing device 2 leaves the electrostatic recording paper 4 and completely dries it. After that, the electrostatic recording paper 4 is rewound onto the original roll, and the next process starts.The operation sound of the same process as above is made, but the developer 2bf, which is supplied with cyan toner, is static. Color images are formed one after another by contacting the recording paper 4 and developing the next color.

Next, details of the developing device and the squeeze device will be explained with reference to FIG. Note that since the arrangement of all the developing devices is the same, only the developing device 2a will be described. The developing device 2a has a slit e on its upper surface at a position in contact with the electrostatic recording paper 4, and this slit 6 has a developing device including a liquid developer tank containing a premix solution, that is, a premix tank 7, and a vacuum pump 8. A liquid circulation system is connected. Furthermore, a solenoid valve 9 is installed in the developer circulation system.
A condenser container 10 is connected via the connector.

The electrode valve 9 is controlled by a concentration sensor 11 disposed in a pipe between the brimix tank 7 and the developing device 2IL,
It opens for a predetermined time when the concentration drops below a predetermined reference value. A vacuum switch 12 is connected to this developer circulation system as a first pressure detection means for detecting changes in the degree of vacuum within the system. On the other hand, the squeeze device 3 also has a slit 13 on its upper surface that contacts the electrostatic recording paper 4, and this slit 13 is connected to a suction system consisting of a vacuum pump 14 and a recovery tank 15. A vacuum switch 16 is also connected to this suction system as second pressure detection means. The output from the vacuum switch 12.16 is input to an abnormality detection circuit (not shown). - In FIG. 1, the normal operating condition will first be explained. When the developer 21L'i is raised by a means not shown and brought into contact with the electrostatic recording paper 4, and at the same time the vacuum pump 8 is operated, a negative pressure is created in the developer circulation system, so the developer in the brimix tank is sucked up. , the slit 6 in the developing device 2a is filled with a developer, and the latent image on the electrostatic recording paper 4 is developed and visualized. After the development is completed, the developer passes through the vacuum pump 8 and is collected into the brimix tank γ. During this time, the concentration sensor 11 detects the entire concentration of the developer, and if the concentration falls below the reference value, the solenoid valve 9 is opened for a certain period of time (for example, 0.2 seconds) to remove the condensate in the condenser container 1o. Supply toner to the developer circulation system.

On the other hand, the developed electrostatic recording paper 4 is simultaneously dried by the flow of air flowing in from the gap between the developing device 21L and the electrostatic recording paper 4. However, at the moment when the operation of the vacuum pump 8 is finished and the developing unit 2ai is lowered, the electrostatic recording paper 4 remains wet because the developer cannot be wiped off from the electrostatic recording paper. When this wet area reaches the slit 13 of the squeeze device 3, when the vacuum pump 14 is operated, the squeeze slit 13 becomes negative pressure, just like during development, so that the electrostatic recording paper 4 and the squeeze device The developer can be wiped off by air flowing in from 30 to 30 minutes, resulting in a completely dry image. The developer wiped off by the squeeze device 3 is collected in a collection tank 16.

Next, an operation for detecting an abnormality in the case of a jam, a shortage of premix liquid, or a shortage of compactor will be explained using the operation flow shown in FIG.

When the electrostatic recording paper 4 is running normally, the developing device 2
The slit 6 on the top surface a is sealed with electrostatic recording paper 4, and the inside of the developer circulation system is maintained at negative pressure by the action of the vacuum pump 8. Therefore, the vacuum switch 12 is kept in the ON state with negative pressure. However, due to meandering of the electrostatic recording paper 4, if the position of the electrostatic recording paper 4 deviates from the position covering the developing slit 6, as shown by the broken line in FIG. The switch 12 indicates atmospheric pressure and is turned off. On the other hand, the same state in which the vacuum switch 12 cannot maintain negative pressure and indicates atmospheric pressure occurs when the liquid in the brimix tank 7 and the condenser container 10 runs out. Therefore, when the vacuum switch 12 generates an OFF signal, it is necessary to determine which cause caused the vacuum in the circulation system to break.

In FIG. 3, first, in step 20, the vacuum switch 1 is
2 has issued an OFF signal.

If the vacuum switch 12 is OFF, proceed to the next step 2.
1, it is determined whether the vacuum switch 12 is OFF for a certain period of time (longer than the opening time of the solenoid valve 9, for example, 0.5 seconds) or more. If the vacuum switch 12 changes from OFF to ON in 0.6 seconds or less, step 22
It is determined whether the solenoid valve 9 is opened or not. At this time, if the solenoid valve 9 is open, there will be a shortage of condensate in the condenser container 1o, and air will enter the circulation system from this container, causing the vacuum in the circulation system to drop. In step 23, a shortage of confectioners is displayed. If the solenoid valve 9 does not open, it is considered that some kind of malfunction has occurred, and the process returns to the original step 2Q.

On the other hand, if the vacuum switch 12 continues to be OFF for 0.5 seconds or more in step 21, the cause may be a jam or a lack of liquid in the premix tank.

In this case, in step 24, the vacuum pump 14 connected to the squeeze device 3 is activated to activate the squeeze device. Next, in step 25, it is determined whether the vacuum switch 16 associated with the squeeze device 3 is OFF. When the electrostatic recording paper 4 is running at a predetermined position above the slit 13 of the squeeze 3, the slit 13 is sealed by the electrostatic recording paper 4, so that the vacuum of the suction system connected to the slit 13 is maintained. The vacuum switch 16 is in the ON state. Therefore, in this case, no jam occurred, and it can be seen that the reason why the vacuum in the circulation system was broken was due to the lack of liquid in the premix tank γ. Therefore, in step 26, a premix liquid shortage display is performed, and then in step 27, after feeding out a predetermined amount of electrostatic recording paper 4, the apparatus is stopped.

When the vacuum switch 1θ is turned off in step 25, the electrostatic recording paper 4 is inserted into the slit 13 of the squeeze device 3.
This is the case when it deviates from the Therefore, in this case, since a jam has occurred, a jam is displayed in step 28, and immediately thereafter, the apparatus is stopped in step 29.

Effects of the Invention As is clear from the above description, in the present invention, signals from the means for detecting the pressure of the developer circulation system and the means for detecting the pressure of the suction system connected to the squeeze device are detected by the abnormality determination circuit. By making judgments in combination with various judgment conditions, it is possible to distinguish between jams, premix liquid shortages, and condenser shortages, and to determine abnormalities. This has the effect that an expensive liquid level detection means is not required and the cost of the apparatus can be reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a developing device and squeeze device to which the present invention is applied, FIG. 2 is a schematic configuration diagram of a color electrostatic recording device, and FIG. 3 is a block diagram showing an abnormality determination operation in an embodiment of the present invention. , FIG. 4 is a schematic diagram of a conventional developing device. 2...Developer, 3...Squeeze device, 4...Electrostatic recording paper, 6...Slit, 7...Premix tank, 8...Vacuum pump, 9...Solenoid valve, 1o...Contentner container, 12...Vacuum switch, 13.
...Slit, 14 ...Vacuum pump, 1
6...Vacuum switch. Name of agent: Patent attorney Toshio Nakao and 1 other person2o
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Claims (1)

[Claims] A first pressure detection means disposed in a liquid developer circulation system having a developing device that contacts a running recording medium to apply a liquid developer, a pump, and a liquid developer tank; A second pressure detection means disposed in a suction system connected to a squeeze device that contacts the medium and sucks up excess liquid developer, and an abnormality detected by signals from the first pressure detection means and the second pressure detection means. a detection circuit, the abnormality detection circuit comprises a first determination means for determining whether or not the abnormality detection signal from the first pressure detection means continues for a predetermined period or more; and a signal of the first determination means. An abnormality detection device for a liquid developing device, comprising means for operating the squeeze device in accordance with the above, and second determination means for determining whether a signal from the second pressure detection means is normal. .