JPH0442269A - Wet developing device - Google Patents

Abstract

PURPOSE:To sufficiently recover the amount of developer in a first developing tank by controlling a developer supply means from a second developing tank to the first developing tank based on the amount of developer in the first developing tank. CONSTITUTION:The developer supply means 71e from the second developing tank 71 to the first developing tank 72 is driven and controlled only while the amount of developer in the first developing tank 72 is reduced. For example, the developer supply means 71e is controlled based on the output of a means 74 which detects the height of a liquid level in the tank 72. In such a way, since the recovery of the amount of developer in the first developing tank 72 can be sufficiently performed even when an image forming operation is performed in a short period, it is possible to prevent a state where the amount of developer is insufficiently supplied to a developing apparatus when the next time of developing is started due to the insufficiency of the developer in the first developing tank 72 occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wet developing device employed in image forming apparatuses such as copying machines, printers, and facsimiles.

[Conventional technology]

Conventionally, this type of wet-type developing device includes a developing device which is equipped with a developer supplying member such as a developing roller inside and supplies a developer to the surface of a photoreceptor that is an image bearing member, and a developer supplied to this developing device. A developing device consisting of a developing tank that stores a liquid is known, and this developing tank is placed in the front side of the image forming apparatus where a door that can be opened and closed is provided near the developing device, taking into consideration the following points. has been done. First, the developer tank is designed to collect the developer from the developer and cleaning device so that even when the power to the device is cut off, the developer returns to the tank by gravity. Place it below the device. Second, the circulation of the developer is synchronized with the main motor's ○N/○FF.
Circulation is not performed during standby, and in a copying machine, after the print button is pressed, the pump operates and pumps the developer from the developer tank to the developer and cleaning device. Until you pump the
Since developing and cleaning cannot be started, which affects the first copy time, the developing tank is placed as close to the developing device and cleaning device as possible. Thirdly, the condenser liquid container that contains a high toner concentration developer and the mother liquid container that contains a developer such as Isopar (trade name) must be replaced when they are empty, so locate them in a location where they can be easily replaced. Place the developing tank in the

However, a conveyance path for conveying transfer paper, etc. to the photoreceptor is formed directly below the developing device, and because there is little space, it is not possible to increase the capacity of the developing tank, and the amount of developer that can be stored There was a problem that the life of the developing solution was shortened.

In addition, since the developer tank is placed on the front side of the image forming apparatus on the conveyance path that conveys the transfer paper, etc. to the photoreceptor, when taking out the jammed transfer paper, etc. on the conveyance path, the developer tank, etc., especially the condenser liquid There was also the problem that the container and mother liquor container were a nuisance.

Therefore, in order to solve these problems, the inventor of the present invention has developed a developing device that supplies a developing solution consisting of toner and a developer to an image bearing member, a first developing tank that stores the developing solution, and a first developing tank that stores the developing solution. He invented a wet-type developing device that has a second developing tank that is provided separately from the developing tank and is supplied with a high-toner concentration developer and a developer, and filed a patent application. FIG. 1 is a schematic configuration diagram of a copying machine that employs a wet developing device according to an embodiment of the patent application, viewed from the front. In this wet type developing device, a small tank 72 which is a first developing tank is used.
Since the large tank 71 and the second developing tank are separated from each other, the small tank 72 is placed close to the developing device 7 and the cleaning device 3 in consideration of the influence on the first copy time. The large tank 71 can be placed at the bottom of the copying machine, where there is a relatively large amount of space, so by making the large tank larger than that of a conventional developing device, the life of the developer can be extended compared to that of a conventional developing device. In addition, if the small tank is made smaller and the location is considered, the second small tank will not get in the way when taking out jammed transfer paper, etc. be.

[Problem to be solved by the invention]

However, when the supply of the developer to the developing device 7 is stopped, the supply of the developer from the small tank 72 to the developing device 7 is stopped, and the development from the large tank 71 to the small tank 72 is stopped. If the supply of liquid is stopped at the same time, the developer in the small tank 72 becomes insufficient when the image forming operation is short (for example, when copying only one sheet), and the large tank 72 becomes insufficient when the next development starts. There is a problem in that there is a risk that the developer supplied to the developing device 7 may run out before the developer from the tank 71 reaches the small tank 72. The reason for this is that when the image forming operation starts, the supply of developer from the small tank 72 to the developing device 7 and the supply of developer from the large tank 71 to the small tank 72 are simultaneously started, and the large tank Until the developer from 71 reaches the small tank 72, the developer in the small tank 72 is supplied to the developing device. After the developer reaches the small tank 72, the difference between the amount of developer supplied from the large tank 71 to the small tank 72 and the amount of developer supplied from the small tank 72 to the developing device 7 (the former is larger) This is because, although this reduction is recovered by increasing the number of pixels (large), this recovery becomes insufficient when the image forming operation is short.

In this way, even when the image forming operation is short, in order to sufficiently recover the amount of developer in the small tank 72, the amount of developer supplied from the large tank 71 to the small tank 72 is reduced from the small tank 72 to the developing device. From the viewpoint of recovering the amount of developer in this small tank 72, it may be possible to make the amount sufficiently large compared to the amount of developer supplied to tank 7, but this would make the supply means (pump or pump drive motor) large. In addition, from the viewpoint of recovering the amount of developer in the small tank 72, if the image forming operation is long enough, even after the amount of developer in the first developer tank has been recovered, the supply means with a large flow rate will ,
Since the developer continues to be supplied from the second developer tank to the first developer link, power is wasted.

The present invention has been made in view of the above-mentioned problems of the prior art, and its objects are to provide a developing device for supplying a developing solution consisting of toner and developer to an image bearing member; A first developer tank that stores the developer supplied to the first developer tank, and a second developer tank that stores the developer supplied to the first developer tank and is supplied with a high toner concentration developer and a developer, respectively. It is an object of the present invention to provide a wet type developing device capable of sufficiently recovering the amount of developer in a first developing tank even when an image forming operation is short.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a developing device that supplies a developing solution consisting of toner and a developer to an image bearing member, a first developing tank that stores the developing solution supplied to the developing device, and a first developing tank that stores the developing solution supplied to the developing device. In a wet type developing device, the first developing tank stores the developing solution supplied to the first developing tank, and the second developing tank is supplied with a high toner concentration developing solution and the developer, respectively. The developer is characterized in that the means for supplying developer to the tank is controlled by the amount of developer in the first developer tank.

[Effect]

In the present invention configured as described above, a first developing tank and a second developing tank are provided which are separated from each other, and the first developing tank is cleaned by cleaning the developing device and cleaning in consideration of the influence on the first copy time. In addition to placing it in a position close to the device, the high toner concentration developer and developer are supplied to the second developer tank, and thereby the first developer tank is equipped with a container containing the high toner concentration developer and developer. On the other hand, the second developing tank can be placed in a location with a relatively large amount of space, thereby making it possible to increase the size of the second developing tank. When starting the supply of developer to the developer, the developer is supplied directly from the first developer tank to the developer, thereby allowing the image forming operation to start quickly. When the amount of developer decreases, the developer supply means from the second developer tank to the first developer tank is driven and controlled to supply the developer from the second developer tank to the first developer tank and then to the developer. When stopping the supply of the developer from the first developer tank, the developer supply means from the second developer tank to the first developer tank is stopped, while the developer supply means from the second developer tank to the first developer tank is The drive is controlled only during the period when the amount of developing solution inside is decreasing.

[Embodiment] An embodiment of the present invention will be described based on FIGS. 1 to 3. In this embodiment, in the copying machine shown in FIG. Control is performed based on the output of the means for detecting the liquid level height.

First, the overall outline of the copying machine will be explained using FIG. 1.

A document on a contact glass 1 is irradiated with an illumination device 2, and the reflected light is transmitted through a scanning mirror 3 and a lens 4 to an image carrier that has already been uniformly charged by a corona discharger 5, which is a negative charger. The image is projected onto a certain drum-shaped photoreceptor 6, thereby forming an electrostatic latent image on the photoreceptor 6. This electrostatic latent image is turned into a toner image by being supplied with a developer by a developing device 7 provided on the right side of the photoreceptor 6. This toner image is conveyed from a paper feed section 8 and transferred to a registration roller 9. The transfer charger 10 transfers the image onto the transfer paper conveyed to the surface of the photoreceptor 6 at the appropriate timing. The transfer paper on which the toner image has been transferred is separated from the photoreceptor 6 by a separation roller 11, passes through a fixing device 12, and is discharged outside the machine as copy paper.

On the other hand, the residual toner on the photoconductor 6 after transfer is removed by a cleaning device 13 provided on the left side of the photoconductor 6, and the residual charge is eliminated by a discharge lamp 14. be prepared for.

Note that the front of the copying machine below the optical system consisting of the illumination device 2, scanning mirror 3, lens 4, etc. is covered by an openable/closable door (not shown), and by opening this door, Each device around the photoreceptor 6, the entire transport path, and even the developing tank at the bottom of the copying machine can be seen from the front.

Next, the developing device will be explained.

The developing device of this embodiment has a large tank 71 installed at the bottom of the copying machine, which is an enlarged version of the developing tank in which the condenser liquid container and the mother liquid container are installed in the conventionally known developing device. A small tank 72, which is a new developing tank smaller than conventionally known developing tanks, is placed in the position where the developing tank was located in the developing device, and is equipped with a developer pump 72a inside and stores the developer. be.

The large tank 71 is provided with a condensation liquid container 71a, a condensation liquid replenishing device 71b, a 9 degree sensor 71C1, a mother liquid container 71d, a pump 71e, and a developer stirring device (not shown). This condenser liquid replenishing device 71
In response to a signal from the concentration sensor 71c installed in the tank at a position where it is always submerged in the developer, when the developer concentration falls below a set value, the solenoid is suction-driven and the developer is placed upside down on the upper lid of the tank 71. The valve of the liquid container 71, which is normally closed by a spring, is
It is opened by pushing the lever and replenishes high toner concentration developer. The mother liquid container is also installed upside down on the upper lid of the tank, and when the developer level in the tank decreases and the developer level in the tank falls below the reference level, the developer discharge port communicates with the atmosphere and releases the liquid inside the container. It is a chicken field valve that replenishes developer into the same tank. Pump 71 installed in the same tank. e is a device for pumping and supplying the developer stored in the tank to the small tank 72 via a developer supply pipe 71f, and is driven by a pump drive motor 71h separate from the main motor 73. , this pump drive motor 71h is driven and controlled based on a signal from a liquid level sensor 74, which will be described later. Further, the lower end of a developer recovery pipe 71g whose upper end communicates with the lowermost portions of the developing device 7 and the cleaning device 13 and the overflow lower 2b of the small tank 72 is connected to the upper lid of the large tank 71. The developer stirring device is for preventing the toner from being unevenly distributed in the large tank 71, and is for pump 71e.
is driven in sync with the

The small tank 72 is arranged on the front side of the conveyance path that conveys the transfer paper to the photoconductor 6, and the upper end of the developer supply pipe 71f from the large tank 72 is connected to the upper lid of the small tank 72.
An overflow lower 2b is provided in the second part, and a developer stirring device (not shown), a liquid level sensor 74 serving as liquid level detection means, and a pump 72a are provided inside. Here, the developer agitating device described in ``1'' is to prevent the toner in the small tank 72 from being unevenly distributed. The liquid level sensor 74
As shown in FIGS. 2(a) and 2(b), reed switches 74a are arranged at regular intervals.

74b and extends vertically; a donut-shaped float 74d that contains a magnet for turning on the reed switches 74a and 74b and is supported by the shaft 74c in a vertically movable manner; and stoppers 74e provided at the upper and lower ends to prevent the float 74d from coming off from the shaft 74c. Here, the reason why the two reed switches 74a and 74b are arranged at a constant interval is that the amount of the developer does not change due to the wave motion of the developer surface that occurs in the small tank due to the drive of the developer stirring device. Since the float 74d moves up and down, this is to create a difference between the liquid level height that moves the pump 71e and the liquid level height that stops the pump. Therefore, instead of the two reed switches 74a and 74b, one reed switch having hysteresis characteristics that can provide a sufficient difference between the ○N/○FF positions may be used.

Upper and lower stoppers 74e and reed switches 74a, 74
The positional relationship with b is that the float 74d is the stopper 74e.
The magnet inside the float 74d is in contact with the reed switch 74a.

74b&ON. Such a liquid level sensor 74 supplies the developing device 7 and the cleaning device 13 during the period from when the pump 71e in the large tank 71 starts driving until the developer in the large tank 71 reaches the small tank 72. With enough developer remaining in the small tank, turn on the lower reed switch 74b.
It is placed in the small tank 72 so that the Above pump 7
2a pumps up and supplies the developer to the developing device 7 and cleaning device 13 through developer supply pipes 72c and 72d, and the pumping flow rate is determined by the pump 71e in the small tank in the large tank 71. The assembly flow rate to 72 is set to be the same or slightly smaller, and driving force is obtained from the main motor 73 of the copying machine via a chain, gear, belt, etc. (not shown), and the main motor 7
It is driven in synchronization with 3.

A pump drive motor 71h that drives the pump 71e in the large tank 71, and a pump 72a in the small tank 72.
As shown in FIG. 3, the main motor 73 provides driving force to the CPU 30 via relays 301 and 302.
They are each connected to an AC power source 304 of 1 m and 100 volts. In addition, the CPU 303 has a print button 3.
05, reed switches 74a and 74b are also connected.

In the second configuration, when the print button 305 is pressed, the main motor 73 of the copying machine is turned on and the pump 72a in the small tank 72 is driven, whereby the developer in the small tank 72 is pumped into the developing device 7. and a small tank 7 and a developer pumped up and supplied to the cleaning device 13 and used for developing and cleaning the photoreceptor 6.
The developer overflowing in step 2 is collected by its own weight into the large tank 71 via the developer collection pipe 71g. When the amount of developer in the small tank 72 decreases and the level of the developer becomes low, the magnet in flow 1-74d turns on the lower reed switch 74b, and the output signal from the CPU 303 turns on the relay 301. The pump drive motor 71h is turned on, and the pump 71e in the large tank 71 is driven to pump up and supply the developer mixed in the large tank 71 to the small tank 72. When the amount of developer in the small tank 72 increases and the liquid level rises, the float 74d also rises and the lower relay switch 74b is turned off.
Furthermore, until the liquid level rises and the upper glue race switch 74a turns on, the relay 30 is not activated from the CPU 303 of J1.
1 continues to be output, and the pump 71e in the large tank 71 continues to be driven.

In this way, in order to output a signal from the CPU 303 to the relay 301, the output port of the CPU 303 to the relay 301 is configured with a latch circuit, and this latch circuit is set by the input signal of the reed switch 74bON, and the relay switch 74a is set. ○I try to reset it with the N signal. When the relay switch 74a is turned on, the relay 30
1 to turn off the pump drive motor 71h,
The pump 71e in the large tank 71 is stopped.

At this time, if the copying operation continues, the developer in the small tank 72 starts to decrease due to the supply of developer to the developing device 7 and cleaning device 13, and as the developer in the small tank 72 decreases, the developer in the small tank 72 starts to decrease. The surface lowers and the upper reed switch 74. a is turned off, but the pump 71e remains stopped, and the liquid level further decreases, causing the lower reed switch 7 to close.
When 4b is turned on, the pump 71e is driven again. Conversely, if the copying operation has been completed at this time, the main motor G turf 3 has stopped and the pump 7 in the small tank 72 has stopped.
2a is also stopped and the supply of developer to the developing device 7 and cleaning device 13 is stopped, so the amount of developer in the small tank 72 does not decrease and the copying machine remains in this state and enters the standby state. Become.

In the second embodiment, the pump 71e in the large tank 71 that supplies developer to the small tank 72 is replaced with the pump 71e in the small tank 72.
The drive is controlled based on the output of the liquid level sensor 74 that detects the developer level in the small tank 72.
Even when the supply of developer to the developing device 7 and cleaning device 13 is stopped, as long as the amount of developer in the small tank 72 has decreased to the extent that it will interfere with the next copying operation, the large tank 72 will continue to operate. Pump 71 in 71. pump 71.e in the large tank 71 to supply developer to the small tank 72 until the amount of developer reaches a level that does not interfere with the next copying operation. There is no need to make e, etc. larger than necessary.

Further, a large tank 71 equipped with a condenser liquid container 71a and a mother liquid container 71d is placed away from the vicinity directly below the developing device 7, and is placed in front of the conveyance path that conveys the transfer paper to the photoreceptor 6. Since the developer is supplied to the small tank 72 located on the side, there is no need to attach the condenser liquid container 7], a or the mother liquid container 71d to the small tank 72, and the life of the developer can be extended. Since the tank 72 can be made smaller without any consideration, the conventional developing tank does not get in the way when taking out jammed transfer paper or the like from the conveyance path in the vicinity of the developing device 7.

Further, the small tank 72 is arranged on the opposite side (inner side) of the front door of the copying machine with respect to the conveyance path of the transfer paper, and accordingly, each developer supply pipe 71f.

72c, 72d and developer recovery pipes 7 ], g are installed on the back side, the small tank 72, each developer supply pipe 71f,
72c, 72d and the developer recovery pipe 71g do not get in the way at all.

In the above embodiment, a means for detecting the developer level was used as a means for detecting the amount of developer in the small tank, which is the first developer tank. It is also possible to use a means for measuring. Similarly, even if the developer level is to be detected, an optical sensor may be used for detection.

〔Effect of the invention〕

As described above, even when the image forming operation is short, it is possible to sufficiently recover the amount of developer in the first developer tank. This has the excellent effect of preventing the occurrence of a situation in which the developer supplied to the developing device is insufficient at the start of development.

[Brief explanation of the drawing]

1 to 3 are drawings for explaining one embodiment of the present invention, in which FIG. 1 is a schematic configuration diagram of a copying machine that employs the wet developing device of this embodiment, viewed from the front, and FIG. FIG. 2(a) is a perspective view of the liquid level sensor, FIG. 2(b) is a front view of the liquid level sensor, and FIG. 3 is a circuit diagram showing the state of connection between the CPU and equipment related to developer supply. 7...Developer, 71...Large tank, 72...Small tank, 71e, 72a ・Pump, 71h...
Pump drive motor 73...Main motor 74
...Liquid level sensor 2,

Claims (2)

[Claims] (1) A developing device that supplies a developer consisting of toner and a developer to an image carrier, a first developing tank that stores the developer that is supplied to the developing device, and a developer that is supplied to the first developing tank. In a wet type developing device equipped with a second developing tank that stores liquid and is supplied with a high toner concentration developer and a developer, a means for supplying a developer from the second developing tank to the first developing tank, A wet type developing device characterized in that control is performed based on the amount of developer in the first developing tank. (2) The wet type developing device according to claim 1, wherein the amount of developer in the first developer tank is detected by means for detecting a liquid level located in the second developer tank.