JPH0750757Y2 - Toner concentration detector for developing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an apparatus for detecting toner concentration in a developing machine used in an image forming apparatus such as an electrophotographic copying machine and a printer.

[Conventional technology]

An image forming apparatus such as an electrophotographic copying machine or a printer develops an electrostatic latent image formed on a photosensitive material into a visible image by a developing machine. The developing machine is a two-component system composed of toner and a carrier. There is one that fills the developer housing in the developing machine housing and conveys the developer toward the photosensitive material by the developing roll to attach toner to the electrostatic latent image on the photosensitive material to develop it into a visible image. Are known.

As described above, in a developing machine using a two-component developer, the toner is consumed for each developing operation, so that the toner concentration of the developer decreases, and if the toner concentration reaches a certain level, proper development may not be possible.

Therefore, conventionally, a hopper is provided in the developing machine housing, and a sensor is provided in the hopper to detect the concentration of the developer flowing in the hopper by the sensor, and when the toner concentration reaches a certain level, the toner is placed in the developing machine housing. Is being replenished.

[Problems to be solved by the device]

In such a toner concentration detecting device, the toner concentration of the developer flowing in the hopper is detected by the sensor. Therefore, if a foreign matter such as a piece of paper is mixed in the hopper, the toner concentration may not be correctly detected by the sensor.

Therefore, an object of the present invention is to provide a toner concentration detecting device for a developing machine, which can solve the above-mentioned problems.

[Means and Actions for Solving the Problems]

(1) In the developer housing 20, a hopper 23 having a large upper inlet 24 and a small lower outlet 25 is installed in the developer housing.
The toner concentration of the developing device is arranged so that the developer in 20 flows in from the upper inlet 24 and flows out from the lower outlet 25, and a sensor 26 is provided to detect the toner concentration of the developer flowing in the hopper 23. In the detection device, the hopper 23 has an upper inlet 24 that opens upward and a lower outlet.
The hopper 23 is movable in a first position in which the upper opening 24 opens downward and in a second position in which the lower outlet 25 opens upward and the hopper 23 moves in the first position and the second position. A drive source for moving the hopper 23 to the
The toner concentration detecting device for the developing machine is configured such that the hopper 23 is in the second posture by the drive source when the foreign matter is discharged.

As a result, the foreign matter in the hopper 23 can be dropped and discharged from the upper inlet 24 together with the developer by setting the hopper 23 in the second posture.

(2) A hopper 23 having a large upper inlet 24 and a small lower outlet 25 in the developer housing 20 is attached to the developer housing.
The toner concentration of the developing device is arranged so that the developer in 20 flows in from the upper inlet 24 and flows out from the lower outlet 25, and a sensor 26 is provided to detect the toner concentration of the developer flowing in the hopper 23. In the detection device, the hopper 23 can be deformed into a first posture in which the lower outlet 25 is small and a second posture in which the lower outlet 25 is large, and the hopper 23 is in the first posture and the second posture. A drive source that moves to the posture is provided, and the hopper 23 is first moved by the drive source during normal operation.
The toner concentration detecting device for the developing machine is configured such that the hopper 23 is in the second posture by the drive source when the foreign matter is discharged.

As a result, by setting the hopper 23 in the second posture, the inside of the hopper 23 becomes large, and the foreign matter can be dropped and discharged together with the developer.

〔Example〕

FIG. 3 shows an example of the image forming apparatus. A drum-shaped photosensitive material 1 is provided in the main body of the image forming apparatus, and a charger 2 for charging the surface of the photosensitive material 1 and a document are provided around the photosensitive material 1. Sensitive material 1
Optical system (not shown) for exposing the surface, photosensitive material 1 by exposure
The developing device 3 for developing the electrostatic latent image formed on the surface of the toner image into a toner image, and the sheet 5 conveyed from the sheet feeding device (not shown) through the sheet conveying path 4 are brought into close contact with the photosensitive material 1 to form a toner image. A transfer device 6 for transferring the sheet 5 onto the sheet 5, a peeling belt 7 for peeling the sheet 5 adhered to the surface of the photosensitive material 1 from the photosensitive material 1 in the transfer step, and a fixing device 8 for the sheet 5 separated by the separating belt 7.
The paper transporting device 9 for transporting the sheet to the photosensitive material 1 is arranged in the above order along the rotation direction of the photosensitive material 1, and the developing device 3 also serves as a cleaner for cleaning the untransferred toner remaining on the surface of the photoreceptor 1 after transfer. ing.

The paper feed path 4 is provided with a feed roll 10, and the paper 5 fed by the feed roll 10 is provided between the first and second sheets 11 and 12.
A sheet 13 is sent between the photosensitive material 1 and the transfer device 6 via the upper shutter 14, and is charged by the transfer device 6 and electrostatically adsorbed on the surface of the photoconductor 1.

The developing machine 3 is provided with a pair of developing rolls 21 and 21 and a mixing member 22 in a developing machine housing 20, and a two-component developer composed of toner and carrier is conveyed to the developing roll 21 by the mixing member 22, The toner is attached to the photosensitive material 1 by 21 to attach toner to the electrostatic latent image to develop it into a visible image, and a hopper 23 is provided on the inner wall surface of the developing machine housing 20. The entrance 24 is wide,
The lower outlet 25 is narrowed and a sensor 26 is provided in the hopper 23 so that the developer flows into the developer housing 20 from the upper inlet 24 and is discharged from the lower outlet 25. The developer circulates in the toner, and the toner concentration of the circulated developer is detected by the sensor 26.

Because of this, the foreign matter such as paper powder is mixed into the hopper 23 and the flow of the developer is obstructed, so that the toner density cannot be accurately detected.

Therefore, as shown in FIGS. 1 and 2, a foreign matter mixing prevention member 30 is attached to the periphery of the upper inlet 24 of the hopper 23 to prevent foreign matter from entering the hopper 23.

That is, the hopper 23 is provided with upper and lower mounting flanges 27 and 28, which are inserted from the mounting opening 29 of the developing device housing 20 to screw the upper and lower mounting flanges 27 and 28 to the developing device housing 20, and prevent the foreign matter from entering. The member 30 has a lattice shape composed of a vertical rod 31 and a horizontal rod 32, and the vertical rod 31 is detachably attached to the peripheral edge of the upper entrance 24 of the hopper 23 so that foreign matters such as paper dust and clips are attached to the vertical rods 31 and 32. Only the developer enters the hopper 23 so as not to enter the hopper 23.

The vertical rods 31 and the horizontal rods 32 are made of a non-magnetic material, and even if the developer collides, the vertical and horizontal rods 31 and 32 themselves are not charged or magnetized by the developer, so that they affect the sensor 26. There is no error in the toner density detection value.

The foreign matter mixing prevention member 30 may have a mesh shape, or
As shown in FIGS. 5 and 5, a plurality of pins 33 made of a non-magnetic material may be attached to the periphery of the upper inlet 24 of the hopper 23 at intervals.

Next, an example of controlling the operation of the toner replenishing device based on the toner density detected by the sensor 26 will be described with reference to FIG.

The sensor 26 outputs a voltage proportional to the toner concentration of the developer, and the output voltage Vout is sent to the first and second comparators 41 and 42 in the control circuit 40 and set in advance by the first comparator 41. When the voltage becomes Vs1 or less commensurate with the low toner concentration, a drive signal is output from the main controller 43 to the toner replenishment motor 44 to replenish the toner in the developer housing 30, and the toner concentration of the developer reaches the set toner concentration. The output voltage Vout of the sensor 26 becomes equal to or higher than the set voltage Vs1, and the toner replenishment motor 44 stops.

The output voltage Vout of the sensor 26 is compared in the second comparator 42 with the voltage Vs2 corresponding to the toner concentration significantly different from the preset low toner concentration, and when the output voltage Vout becomes equal to or lower than the voltage Vs2, the constant supply controller 45. A signal is output to drive the toner replenishment motor 44 at a constant speed to replenish a fixed amount of toner, and at the same time, the display member 46 performs a display operation.

By controlling in this way, the operator can know from the display member 46 that foreign matter such as paper dust has been erroneously mixed into the hopper 23, and the repair work can be performed accordingly. Can be prevented from being replenished in vain.

That is, when foreign matter is mixed into the hopper 23, the flow of the developer is obstructed and the toner concentration detected by the sensor 26 fluctuates remarkably, so that the output voltage Vout of the sensor 26 remarkably changes. By detecting that foreign matter is mixed in the hopper 23, the toner replenishment motor 44 is driven at a constant speed to replenish a fixed amount of toner by the detection, and the operator operates the display member 46 to display. I can detect it.

Further, as shown in FIGS. 7 and 8, both side walls 23a, 23a and the bottom wall 23b of the hopper 23 can be freely opened and closed by a solenoid, an air cylinder or the like, and the side walls 23a, 23a and the bottom wall 23b can be opened at any time. May be opened to open the lower outlet 25 to discharge the foreign matter in the hopper 23.

Further, as shown in FIGS. 9 and 10, the hopper 23 is formed into a substantially U-shape in a plan view, and the sensor 26 is attached to the developing machine housing 20 side. Respectively, the arm 50 is connected to the rotary shaft 52, the gear 53 fixed to the rotary shaft 52 is meshed with the gear 55 rotated by the motor 54, and the motor 54 is driven to drive the motor 54 together with the hopper 23. 10 can be turned upside down by 180 degrees between the upward posture shown by the solid line and the downward posture shown by the phantom line so that the hopper 23 is set to the downward posture at any time and the foreign substance a in the hopper 23 is made into a large upper entrance. You may make it discharge from 24. In FIG. 10, the support piece 51 is in contact with the stopper 56 in the upward posture.

In addition, as shown in FIG. 11, FIG. 12 and FIG.
23 together with the sensor 26 by the rotary solenoid 57 to be rotatable in the upward posture shown in FIG. 12 and the downward posture shown in FIG. 13, and the popper 23 may be rotated in the downward posture at any time. good.

In other words, since the upper inlet 24 of the hopper 23 is large and the lower outlet 25 is small, it cannot be discharged if foreign matter such as paper powder is mixed in, so that both side walls 23a, 23a, the bottom wall 23b are opened to make the lower outlet 25 large or large. The upper inlet 24 may be turned downward so that the foreign matter mixed in the hopper 23 can be discharged.

The time at which the side walls 23a, 23a, the bottom wall 23b are opened or the hopper 23 is rotated is determined by the above-mentioned signal that detects the contamination of foreign matter or when the main power of the image forming apparatus is turned on and when the image forming apparatus is in operation. It may be done every hour or the like.

[Effect of device]

According to the first invention, since the upper inlet 24 of the hopper 23 is large and the lower outlet 25 is small, the developer easily enters the hopper 23, and the developer is less likely to drop from the hopper 23, so that the developer is less likely to fall into the hopper 23. A large amount of developer flows slowly, and the sensor 26 can accurately detect the toner concentration of the developer.

Moreover, since the large upper inlet 24 is opened downward by setting the hopper 23 in the second position, foreign matters mixed in the hopper 23 can be dropped and discharged together with the developer, and a large amount of foreign matters are mixed in the hopper 23. The toner concentration of the developer can be accurately detected by preventing it in advance.

According to the second invention, since the upper inlet 24 of the hopper 23 is large and the lower outlet 25 is small, the developer easily enters the hopper 23, and the developer is less likely to drop from the hopper 23, so that the developer enters the hopper 23. A large amount of developer flows slowly, and the sensor 26 can accurately detect the toner concentration of the developer.

Moreover, by making the hopper 23 in the second position, the lower outlet 25
The foreign matter mixed in the hopper 23 can be dropped and discharged together with the developer, and a large amount of foreign matter can be prevented from mixing in the hopper 23, and the toner concentration of the developer can be accurately detected.

[Brief description of drawings]

The drawings show the embodiments of the present invention, FIG. 1 is an enlarged explanatory view of a developing machine, FIG. 2 is a perspective view of a hopper, and FIG. 3 is an explanatory view showing an example of an image forming apparatus, FIGS. FIG. 6 is a cross-sectional view showing a modified example of the foreign matter mixture prevention member in a mounted state, a perspective view of a hopper, FIG. 6 is a toner supply control circuit diagram, and FIGS. 7 and 8 are perspective views showing a modified example of the hopper. 9 and 10 are a plan view, a front view, and a plan view showing an example in which the hopper is inverted.
FIG. 11, FIG. 12, and FIG. 13 are a sectional view, a front view, and an operation explanatory view showing an example in which the hopper is rotated. 20 is a developer housing, 23 is a hopper, 24 is an upper entrance,
25 is a lower outlet, 26 is a sensor, and 30 is a foreign matter mixture preventing member.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Yukita 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Co., Ltd.Ebina business office (72) Masamitsu Furukawa 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Co., Ltd. Inside the Ebina Works (72) Inventor Toshikazu Kageyama 2274 Hongo, Ebina City, Kanagawa Fuji Xerox Co., Ltd. Inside the Ebina Works (56) References: 59-95364 (JP, U), 63-157762 (JP) , U)

Claims (2)

[Scope of utility model registration request] 1. A large upper inlet 24 within the developer housing 20.
And a small bottom outlet 25, the developer in the developer housing 20 flows in through the upper inlet 24 and the lower outlet.
In the toner concentration detecting device of the developing device, which is provided so as to flow out from the hopper 23, and which is provided with the sensor 26 for detecting the toner concentration of the developer flowing in the hopper 23, the hopper 23 is arranged so that the upper inlet 24 is upward. Open and lower exit
The hopper 23 is movable in a first position in which the upper opening 24 opens downward and in a second position in which the lower outlet 25 opens upward and the hopper 23 moves in the first position and the second position. A drive source for moving the hopper 23 to the
And the hopper 23 is brought into the second posture by the drive source when the foreign matter is discharged. 2. A large upper inlet 24 in the developing machine housing 20.
And a small bottom outlet 25, the developer in the developer housing 20 flows in through the upper inlet 24 and the lower outlet.
In the toner concentration detecting device of the developing device, which is arranged so as to flow out from the hopper 23 and is provided with a sensor 26 for detecting the toner concentration of the developer flowing in the hopper 23, the hopper 23 is made smaller at the lower outlet 25. A first position and a second position in which the lower outlet 25 is enlarged, and a drive source for moving the hopper 23 between the first position and the second position is provided. 23 first
And the hopper 23 is set to the second posture by the drive source when the foreign matter is discharged.