JPH08305147A - Developing device - Google Patents

Abstract

PURPOSE: To attain the release of a stopping mechanism at the time of starting the supply of toner by small force by adding torque to a third screw in the direction opposite to the direction of rotation of a first screw. CONSTITUTION: The rotation of a gear 49 is stopped by a stopper 71 and the rotation of a gear 44 engaged with the gear 49 via an intermediate gear 50 is stopped. Therefore, the rotation of a supporting member 63 fixed on the gear 44 is stopped to stop the rotation of the third screw fixed on the supporting member 63. When a magnetic sensor detects the fact that the toner concentration of a developer is made to have a valve lower than a prescribed one, a second rotary mechanism is actuated so that the torque for rotating the gear 49 in the direction of rotation opposite to the direction of rotation (the arrow G) of a first shaft is added to a supporting member 67 and the torque exerted on the third screw by the rotation of a first rotary shaft is reduced to release the engagement of the stopper 71 and the gear 49.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is for carrying out image formation.
The present invention relates to a developing device configured to use a two-component developer including toner and carrier.

[0002]

2. Description of the Related Art Generally, an image forming apparatus has a structure as shown in FIG. That is, the image forming apparatus 1 such as a copying machine or a printer is roughly divided into an image forming section 2, a transfer material conveyance guide means 3, and a fixing device 4. As is well known, as the image forming unit 2, a corona charger 6 for uniformly charging the surface of the photosensitive drum 5 around the photosensitive drum 5, original data read by a scanner or the like is projected by an LED or the like to form the photosensitive drum. 5, an optical projection device 7 for forming a latent image on it, a developing device 8 for developing this latent image, and a developed toner image transferred to a transfer material fed from a paper feeding unit 9 loaded with roll paper (or cut paper) Transfer corona discharger 10, AC separation corona discharger 11 for separating the transfer material from the photosensitive drum 5, and cleaning device 1 for removing the toner remaining on the surface of the photosensitive drum 5 after transfer
2. An eraser lamp 13 for uniformly removing the surface potential of the surface of the photosensitive drum 5 is provided, and these are arranged so as to sequentially act on the photosensitive drum 5.

At one end of the cleaning device 12, a toner guide cylinder 14 for guiding the waste toner collected by a cleaning blade or the like to the outside of the apparatus is provided.
The tip of 4 is connected to a discharge port 16 provided in the waste toner container 15. Further, between the vicinity of the separating corona discharger 11 and the fixing device 4, the transfer material separated from the photosensitive drum 5 by the separating corona discharger 11 is conveyed to the fixing device 4 by a conveying belt 17 as guide means 3 and a guide. A plate 18 is arranged. A fixing device 4 for fixing the toner image on the transfer material as a permanent image is arranged at the tip of the guide plate 18. A toner supply port 19 is provided at one end of the developing device 8 in the longitudinal direction (on the side surface in the axial direction of the photosensitive drum) so that the supply port 21 of the toner cartridge 20 does not scatter toner into the device during supply. It is covered with the guide member 22 and pressed around the mouth by a sponge 23 or the like to be connected.

Details of the developing device 8 are shown in FIG.
In the figure, the casing 24 of the developing device 8 has an opening 25 facing a part of the surface of the photosensitive drum 5, and a part of the peripheral surface is exposed from the opening 25 so as to approach the photosensitive drum 5. Is provided with a developing roller 26. The developing roller 26 is composed of a permanent magnet 27 fixedly arranged inside and a sleeve 28 that rotates the outer circumference of the permanent magnet 27 by an arrow C, and the developer 31 is attracted to the surface of the sleeve 28 by the magnetic force of the permanent magnet 27. To form the magnetic brush 29.
The magnetic brush 29 is regulated to a constant thickness by the regulation plate 30, and comes into contact with the surface of the photosensitive drum 5 on which a latent image is formed to develop it. The developer 31 remaining on the surface of the sleeve 28 after the development is mixed with the developer 31 stirred in the developing device 8 in a place where the permanent magnet 27 is not affected. Figure 6
The internal structure of the casing 24 of the developing device 8 is shown in FIG. Two housing chambers 33 and 34 are formed in the casing 24 by the partition plate 32. A toner supply port 35 for introducing toner into the storage chamber 33 is provided at one end of the storage chamber 33.
However, a developer discharge port 36 for discharging the toner from the storage chamber 34 to the outside is provided at one end of the storage chamber 34.

Further, as shown in FIG. 5, inside the casing 24 of the developing device 8, at least two screws adjacent to the developing roller 26 for stirring the developer 31, that is, the first screw 37 in this example, The second screw 38 is provided close to the inner surface of the casing 24. As shown in the drawing, the bottom of the casing 24 is stepwise so as to draw a double arc so as to surround a part of the first screw 37 and the second screw 38. The screw 38 located in the vicinity of the developing roller 34 is configured by spirally forming stirring blades 38B along the axial direction on the outer circumference of a shaft 38A at substantially equal intervals. The screw 37 on the side away from the developing roller 26 is the stirring blade 3 similar to the screw 38.
Have 8B.

A first rotary shaft 39 is inserted into the storage chamber 33 shown in FIG.
Both ends of the casing 24 penetrate through the casing 24
It is rotatably supported by. A gear 40 is fixed to the first rotating shaft 39 protruding from the casing 24, and a motor 41 is attached to an end portion of the first rotating shaft 39. The motor 41 serves as a rotational drive source for the first rotary shaft 39 and rotates the first rotary shaft 39. The first rotating shaft 39 is inserted through the center of the first screw 37, and the first screw 37 is fixed to the first rotating shaft 39. A third screw 42 is rotatably fitted to the first rotating shaft 39 via bearings 60 and 61 attached to both ends thereof. The tip of the third screw 42 does not come into contact with the first screw 37, and the end of the third screw 42 is fixed to a support member 63 rotatably attached to the casing 24 via a bearing 62. There is. The first rotation transmission mechanism 43 is attached to the other end of the first rotation shaft 39.
The third screw 42 is attached to the rotation transmission mechanism 43 via the support member 63. The first rotation transmission mechanism 43 is an electromagnetic clutch that can be turned on and off by turning the power supply on and off.
The rotation force of the third screw 4 is applied to the third screw 4 via the support member 63.
It is transmitted to 2. This first rotation transmission mechanism 43
Is operated, the support member 63 rotates, and the support member 63
The third screw 42 fixedly attached to the shaft is adapted to rotate. Reference numeral 44 denotes a gear, which is fixed or adhered to one end of a support member 63 protruding to the outside of the casing 24, and the rotation of the motor 41 is rotated by the operation of the first rotation transmission mechanism 43 when the motor 41 operates. 39, 1st
It is transmitted to the support member 63 and the gear 44 fixed or adhered thereto via the rotation transmission mechanism 43 to rotate.

On the other hand, a second rotary shaft 45 is inserted into the storage chamber 34, and both ends of the second rotary shaft 45 penetrate the casing 24 and are rotatably supported by the casing 24. ing. A gear 46 is fixed to the second rotary shaft 45 protruding from the casing 24, and the gear 46 is meshed with a gear 40 fixed to the first rotary shaft 39. This gear 46
Means that the first rotary shaft 39 is the second rotary shaft 45.
Of the gear 40 that rotates as the first rotation shaft 39 rotates. That is, as shown in FIG. 5, when the first rotating shaft 39 rotates in the direction indicated by the arrow A by the drive of the motor 41, the second rotating shaft 45 causes the second rotating shaft 45 via the gear 40 to move toward the arrow B.
The second rotating shaft 45 rotates in the direction shown in FIG.
The rotary shaft 39 rotates in the opposite direction. The second rotary shaft 45 is inserted through the center of the second screw 38, and the second screw 38 is fixed to the second rotary shaft 45. Therefore, the second screw 38 rotates in the direction opposite to the rotation direction of the fourth screw 47 due to the rotation of the first rotating shaft 39.

The second rotating shaft 45 has a fourth
Screw 47 is rotatably fitted through bearings 64 and 65 attached to both ends thereof.
Further, the tip of the fourth screw 47 does not come into contact with the second screw 38, and the end thereof is fixed to a support member 67 rotatably attached to the casing 24 via a bearing 66. There is. Also, the second
The other end of the rotation shaft 45 of the second rotation transmission mechanism 4
8 is attached to the second rotation transmission mechanism 48.
The fourth screw 47 is attached to the support member 63 via the support member 63. The second rotation transmission mechanism 48 is an electromagnetic clutch that can be turned on and off by turning the power supply on and off, and the torque of the second rotation shaft 45 is applied to the fourth screw 47 via the support member 67. It is something to convey. That is, the second rotation transmission mechanism 48 is
The screw 47 is rotated in the same direction as the rotation direction of the second rotary shaft 45 (direction different from the rotation direction of the first screw 37).

Therefore, when the second rotation transmission mechanism 48 operates, the rotation of the second rotation shaft 45 is transmitted, the support member 67 rotates, and the fourth screw 47 fixed to this support member 67 rotates. It is like this. 49
Is a gear, which is fixed or adhered to one end of a support member 67 protruding to the outside of the casing 24.
When the second rotation transmission mechanism 48 is activated during the operation of, the rotation of the motor 41 is transmitted to the support member 67 and the gear 49 fixed or adhered thereto via the shaft 45 and the second rotation transmission mechanism 48 to rotate. To do. The gear 49 is meshed with the gear 44 via the intermediate gear 50. Therefore, the gear 44 rotates in the same direction as the gear 49. That is, when the first rotation transmission mechanism 43 is operated, the third screw 42 and the fourth screw 47 are
It rotates in the same direction as the rotating direction of the first rotating shaft 39 (opposite to the rotating direction of the second rotating shaft 45),
When the second rotation transmission mechanism 47 is operated, the third screw 42 and the fourth screw 47 move in the same direction as the rotation direction of the second rotation shaft 45 (opposite to the rotation direction of the first rotation shaft 39). ) Will be rotated. At the time of development, the rotation direction of the first rotation shaft 39 is always a constant direction (direction shown by arrow A), and the rotation direction of the second rotation shaft 45 is opposite to the rotation direction of the first rotation shaft 39 (arrow direction). It always rotates in the direction indicated by B). Therefore, the first rotation transmission mechanism 43 and the second rotation transmission mechanism 4
It will not be thrown in simultaneously with 7.

In this way, the first rotation transmission mechanism 43
Is activated, the rotation of the first rotating shaft 39 is transmitted, the third screw 42 rotates, and the gear 44 fixed to the third screw 42 rotates. Then, the rotation of the gear 44 is transmitted to the gear 49 via the intermediate gear 50, and the fourth screw 47 to which the gear 49 is fixed is rotated in the same direction as the rotation direction of the third screw 42. Become. Further, the second rotation transmission mechanism 48 operates, the rotation of the second rotation shaft 45 is transmitted, the fourth screw 47 rotates, and the gear 49 fixed to the fourth screw 47 rotates. Then, the rotation of the gear 49 is transmitted to the gear 44 via the intermediate gear 50, and the third screw 42 to which the gear 44 is fixed is rotated in the same direction as the rotation direction of the fourth screw 47. Become. Thus, the rotation of the first rotary shaft 39 and the second rotary shaft 39
As can be seen from the rotation of the rotating shaft 45 in the opposite directions, the rotation directions of the third screw 42 and the fourth screw 47 when the first rotation transmission mechanism 43 is turned on, The rotation directions of the third screw 42 and the fourth screw 47 when the second rotation transmission mechanism 48 is turned on are opposite to each other. Therefore, the first rotation transmission mechanism 43 and the second rotation transmission mechanism 48 do not enter at the same time. Therefore, the first rotation transmission mechanism 43 and the second rotation transmission mechanism 43
The rotation transmission mechanism 47 is not turned on at the same time.

The partition plate 32 has two ends on the side opposite to the side where the toner supply port 35 and the toner discharge port 36 are formed.
A first communication passage 52 that connects the two storage chambers 33 and 34 is formed. Further, in the partition plate 32, the storage chamber 33 is provided in the vicinity of the front end where the first screw 37 and the third screw 42 face each other and in the vicinity of the front end where the second screw 38 and the fourth screw 47 face each other. A second communication passage 53 that communicates between the storage chamber 34 and the storage chamber 34 is formed.

A magnetic sensor 5 is provided on the side surface of the developing device 8.
4 is provided to detect the magnetic permeability of the developer 31, and the toner concentration of the developer 31 in the storage chamber 33 is detected based on the detected magnetic permeability. In addition, the storage chamber 33,
The screws 37 and 38 housed in the screw 34 are arranged in parallel so that the developer conveying directions are different from each other, and the partition plate 32 is provided between the screws 37 and 38. Then, the developer 31 is supplied with the screws 37, 3
The carrier is circulated in the width direction 8 to uniformly mix the carrier and the toner. Reference numeral 55 denotes a toner detection sensor, which detects the presence or absence of toner supplied from the toner cartridge 20, and when toner is no longer supplied from the toner cartridge 20, that is, the toner cartridge 20.
A detection signal is sent when the toner runs out.

[0013]

In the image forming apparatus 1 shown in FIG. 4, the corona charger 22 uniformly charges the photosensitive drum 5, and the optical projection device 7 transfers the image data to the photosensitive drum 5. Project on top to form a latent image. Next, the developing device 8 develops the latent image to form a toner image. On the other hand, the transfer material as the roll paper loaded in the paper feeding unit 9 is conveyed to the photosensitive drum 5 in synchronization with the rotation speed of the photosensitive drum 5. On the transfer material, the toner image on the photosensitive drum 5 is transferred onto the transfer material by the transfer corona discharger 10, and by the separation corona discharger 11 the photosensitive drum 5 is transferred.
And is conveyed to the fixing device 4 by the conveyance belt 25, fixed as a permanent image, and discharged outside the apparatus. The toner remaining on the photosensitive drum 5 after development is removed from the surface of the photosensitive drum 5 by the cleaning device 12, and then the photosensitive drum 5 is neutralized by the eraser lamp 13 and prepared for the next image formation.

For example, as shown in FIG. 6, the height of the developer is filled to such an extent as to cover the upper portions of the first screw 37 and the second screw 38, and the first screw 37 and the second screw 38 develop. The developer 31 in the device 8 is agitated while being circulated in the width direction of the screws 37 and 38. The developer 31 circulates in the storage chambers 33 and 34 in the first communication passage 52 and the second communication passage 53 that communicate the two storage chambers 33 and 34 of the partition plate 32. First screw 37, second
Screw 38 is driven when development is performed.
The developer 31 thus stirred and mixed by the second screw 38 is adsorbed by the developing roller 26 and comes into contact with the surface of the photosensitive drum 5 on which a latent image is formed, releases toner and develops the photosensitive drum 5. Therefore, the toner mixed with the carrier is consumed as the image is formed. During this driving, the magnetic sensor 54 detects the toner concentration in the developer.

When the toner is consumed in accordance with the image formation and the magnetic sensor 54 detects the toner concentration of the developer 31, and the toner concentration in the developer 31 is lower than a predetermined value, a detection signal is output and the first rotation is performed. The transmission mechanism 43 is operated to transmit the rotation of the first rotating shaft 39 to the third screw 42 to rotate the third screw 42. The toner supplied from the toner cartridge 20 to the toner supply port 35 by the rotation of the third screw 42 is conveyed to the tip portion of the first screw 37 by the conveying action of the third screw 42. The toner conveyed to the tip portion of the first screw 37 is taken up by the first screw 37, and the action of the first screw 37 causes the first communication passage 52 to pass.
Of the toner 31 whose toner concentration has decreased by the time
Is mixed with, and is conveyed to the first communication passage 52 while being stirred. Developer 31 mixed with replenished toner
The second screw 3 after passing through the first communication passage 52.
8 and the mixture is repeatedly stirred and mixed until it reaches the second communication passage 53 by the action of the second screw 38, and is conveyed to the second communication passage 53. The developer 31 conveyed to the second communication passage 53 is transferred to the second communication passage 53.
The toner, which has been conveyed by the third screw 42, is taken up by the first screw 37, and the first screw 37 repeats the stirring / mixing operation and the second screw 38 repeats the stirring / mixing operation. And
The toner is supplied by the rotation of the third screw 42 until the developer 31 reaches a predetermined toner concentration. Therefore, the third screw 42 is rotated in the first direction when the magnetic sensor 54 detects that the toner is consumed in accordance with the image formation and the toner concentration in the developer 31 in the storage chamber 33 is lower than a predetermined value. When the transmission mechanism 43 is operated to rotate and the toner concentration in the developer reaches a predetermined concentration, the first
The rotation transmission mechanism 43 is released and stopped.

By the way, since the toner used in the developer 31 is a fine powder, the bearing 62 and the first bearing 62 provided at both ends of the third screw 42 each time the third screw 42 is rotationally driven. The toner that has entered the gap with the rotating shaft 39 adheres between the bearing 62 and the first rotating shaft 39, and becomes the rotational friction of the bearing 62 when the first rotating shaft 39 rotates. A kind of image sticking occurs when the developing device 8 is used for a long time (frequency of use) due to frictional heat generated by the rotation of the screw 42. Therefore, the toner density in the developer 31 is higher than a predetermined value, and the toner cartridge 20
It is not necessary to replenish the toner supplied from the toner supply port 35 to the toner supply port 35, and even when the rotation of the third screw 42 is stopped, the rotation of the first rotation shaft 39 is accompanied (rotation phenomenon). Will end up.

An object of the present invention is to rotate the first rotary shaft when the toner concentration in the developer is higher than a predetermined value and it is not necessary to replenish the toner from the toner cartridge and the third screw is stopped. Even if the first rotating shaft is rotated, the stop mechanism for stopping the rotation of the third screw due to the follow-up phenomenon can be released with a small force. It is to try.

[0018]

According to a first aspect of the present invention, there is provided a developing device in which a two-component developer of toner and carrier supplied from a toner cartridge is filled in a casing of the developing device, and the casing is A first screw for partitioning into two storage chambers by a partition plate and for conveying the toner and the carrier to one of the storage chambers while mixing and agitating them, and the first screw disposed on the axis of the first screw. Accommodates a third screw that rotates independently of the rotation of the first screw and that conveys the toner supplied from the toner cartridge to the tip of the first screw, and the other accommodation chamber is interlocked with the first screw. And a second screw that rotates in a direction opposite to the rotation direction of the first screw and circulates the developer conveyed by the first screw while stirring. Is provided on the axis of the screw and rotates independently of the rotation of the second screw in conjunction with the third screw to convey the developer in the casing to the tip of the second screw, or A fourth screw that conveys the developer, which has been conveyed to the tip of the second screw by the second screw, toward the discharge port is accommodated, and the accommodation chamber in which the first screw is accommodated In the developing device for driving the third screw to convey the toner to the tip portion of the first screw when the toner concentration of the developer becomes lower than a predetermined value,
Is provided with a stop mechanism for stopping the third screw so that the screw does not rotate when the toner supply is stopped, and when the toner supply is started, the stop mechanism is released by the first screw. This is done by applying a rotational force in a direction opposite to the rotational direction of the screw.

A developing device according to a second aspect of the invention is
The first screw is fixed to a first rotary shaft that is inserted through the center of the first screw, and is rotated by driving the first rotary shaft by a motor to rotate the second screw. , Receives the rotation of the first rotating shaft, is fixed to the second rotating shaft that rotates in a direction opposite to the rotation of the first rotating shaft, and rotates in synchronization with the rotation of the second rotating shaft. It was done.

A developing device according to a third aspect of the invention is
The third screw is formed in a tubular shape and is rotatably fitted to the first rotating shaft, and is rotated by a first rotation transmitting mechanism that transmits the rotation of the first rotating shaft using a clutch. The second screw is rotatably fitted to the second rotating shaft and is rotated in conjunction with the third screw. The first rotation transmission mechanism rotates the third screw. The first screw is rotated in the same direction or is rotated in the opposite direction to the rotation direction of the first screw by a second rotation transmission mechanism that transmits the rotation of the second rotation shaft using a clutch. .

A developing device according to a fourth aspect of the present invention is
The stop mechanism is composed of a stopper that is attached to and detached from the gear attached to the second rotation transmission mechanism by the action of a solenoid, and the release of the stop mechanism at the time of starting the toner supply is performed by closing the clutch to release the second rotation transmission mechanism. Is actuated to apply a rotational force to the fourth screw in the same direction as the rotational direction of the second rotary shaft, and then the solenoid is actuated to remove the stopper engaged with the gear.

[0022]

According to the first aspect of the present invention, the two storage chambers are partitioned by the partition plate, the two-component developer of toner and carrier is filled in the casing of the developing device, and one storage chamber is provided with the first screw. And rotating independently of rotation of the first screw to supply toner to the first screw.
Second screw, which rotates in the opposite direction in conjunction with the first screw in the other storage chamber, and the other storage chamber, rotates independently of the rotation of the second screw and rotates in conjunction with the third screw to develop. A developing device that accommodates a fourth screw that conveys an agent, and drives the third screw to replenish the toner when the toner concentration of the developer in the accommodation chamber becomes lower than a predetermined value. A stop mechanism for stopping the third screw so as not to rotate when the toner supply is stopped is provided, and the release of the stop mechanism causes the third screw to rotate when the toner supply is started. The toner concentration in the developer is higher than a predetermined value, and it is not necessary to replenish the toner from the toner cartridge. Even if the first rotating shaft rotates, the accompanying rotation phenomenon does not occur when stopped, and even if the first rotating shaft rotates, the rotation of the third screw due to the accompanying rotation phenomenon is stopped. The stop mechanism can be released with a small force.

According to the second aspect of the present invention, the first screw is fixed to the first rotary shaft that is inserted through the center of the first screw, and the first screw is attached by the motor.
By rotating the rotating shaft of the
Screw is fixed to a second rotating shaft that rotates in a direction opposite to the rotation of the first rotating shaft by receiving rotation of the first rotating shaft, and rotates in synchronization with rotation of the second rotating shaft. Therefore, the rotation of the third screw can be rotated in the opposite direction of the rotation of the first rotating shaft by using the rotation of the second rotating shaft of the fourth screw, and the third screw can be rotated with a small force. The stop mechanism that stops the rotation of the screw can be released.

According to the third aspect of the invention, the third screw is rotated by the first rotation transmission mechanism that transmits the rotation of the first rotation shaft by using the clutch, and the fourth screw is rotated by the first rotation transmission mechanism.
The screw is rotated in conjunction with the third screw, and is rotated in the same direction as the rotation direction of the third screw by the first rotation transmission mechanism or by the first rotation transmission mechanism by the first rotation transmission mechanism. Since the screw is rotated in the direction opposite to the rotating direction of the screw, the third screw is rotated in the opposite direction from the rotation of the first rotating shaft by utilizing the rotation of the second rotating shaft of the fourth screw. Therefore, the stop mechanism that stops the rotation of the third screw can be released with a small force.

According to the fourth aspect of the invention, the stop mechanism is constituted by a stopper which is attached to and detached from the gear attached to the second rotation transmission mechanism by the action of the solenoid, and the stop mechanism of the stop mechanism at the time of starting the toner supply. To release the stopper, the second rotation transmission mechanism is operated to apply a rotational force to the fourth screw in the same direction as the rotation direction of the second rotation shaft, and then a solenoid is actuated to engage the gear. Therefore, the stop mechanism that stops the rotation of the third screw can be released with a small force.

[0026]

Embodiments of the present invention will be described below. 1 to 3 show an embodiment of the developing device according to the present invention. An image forming apparatus in which the developing device according to the present invention is preferably used is the same as the image forming apparatus shown in FIG. FIG. 1 shows a casing 2 of a developing device 8 according to the present invention.
The internal configuration of 4 is shown. In FIG. 1, parts having the same reference numerals as those in FIG.
The same parts are shown.

This embodiment is different from the developing device 8 shown in FIG. 6 in that it meshes with a gear 49 fixed to a support member 67 to which a fourth screw 47 protruding outside the casing 24 is fixed. The stop mechanism 70 is provided. Others have the same configuration as the developing device 8 shown in FIG.

The stop mechanism 70 has a structure as shown in FIG. Reference numeral 71 denotes a stopper, the tip of which is detachably engaged with the gear 49 as shown in FIG. The stopper 71 is fixed to one end of an arm 72, and the arm 72 is rotatably attached by a pin 74 to a fixing member 73 fixed to the casing 24 at substantially the center. The other end of the arm 72 is rotatably attached to a solenoid drive rod 76 which is driven by a solenoid main body 75 to move as shown by an arrow D in FIG.

Next, the operation of this embodiment will be described.
When the toner concentration of the developer 31 in the storage chamber 33 of the developing device 8 is higher than a predetermined value, the stopper 71 meshes with the gear 49 as shown in FIG. The rotation of the fourth screw 47 fixed to the support member 67 is stopped by stopping the rotation of the support member 67. When the rotation of the gear 49 is stopped by the stopper 71, the rotation of the gear 44 that meshes with the gear 49 via the intermediate gear 50 is stopped.
By stopping the rotation of the gear 44, the rotation of the support member 63 fixed to the gear 44 is stopped, and the rotation of the third screw 42 fixed to the support member 63 is stopped. When the developing device 8 operates and develops,
When the toner concentration of the developer 31 in the storage chamber 33 is higher than the predetermined value, it is not necessary to replenish the toner, and therefore the third screw 42 is not rotated. However, the fine powder toner enters through the gap between the bearing 62 provided at both ends of the third screw 42 and the first rotating shaft 39, and the entered toner forms the bearing 62 and the first rotating shaft 39. Adhered between
Bearing 62 when the first rotating shaft 39 rotates
As a result of rotational friction of the third screw 42, the third screw 42 acts as a force to rotate in the same direction as the first rotating shaft 39 as indicated by an arrow G in FIG.
If 2 is not stopped, it will rotate together with the first rotating shaft 39.

Then, as shown in FIG. 2, the solenoid main body is operated and the solenoid drive rod 76 is projected to move the arm 42.
Is rotated to engage the stopper 71 with the gear 49 to prevent the third screw 42 from rotating. When the stopper 71 is engaged with the gear 49 in this way, the rotation of the third screw 42 is suppressed, the first rotating shaft 39 rotates, and the rotation of the first rotating shaft 39 causes the first screw shaft 39 to rotate.
Screw 37 rotates, but the third screw 42
Will idle around the first rotating shaft 39. However, the rotation of the first rotary shaft 39 causes the toner, which is a fine powder, to be caught in the gap between the bearing 62 provided at both ends of the third screw 42 and the first rotary shaft 39. The trapped toner becomes a rotation load when the third screw 42 rotates, and the third screw 42, which should originally be idle, is illustrated in the gear 44 in FIG. 2 by the rotation of the first rotating shaft 39. As indicated by the arrow G in FIG.
The force that tries to rotate in the same direction as the rotation of works. This first gear 44 is added to the gear 44 as shown by an arrow G in FIG.
The force to rotate in the same direction as the rotation of the rotary shaft 39 is to the gear 49 via the intermediate gear 50 to rotate in the same direction as the rotation direction of the gear 44 as shown by the arrow H in FIG. Acts, and the rotational force applied to the gear 49 is applied to the stopper 71 that is engaged with the gear 49.

When the strong rotational force of the gear 49 is applied to the stopper 71 in this way, when the toner is consumed as the image is formed and the toner concentration of the developer 31 becomes lower than a predetermined value, the magnetic sensor 54 lowers the toner concentration. Is detected to operate the first rotation transmission mechanism 43 to transmit the rotation of the first rotation shaft 39 to the third screw 42 and rotate the rotation.
The stopper 71 does not disengage from the gear 49 and the third screw 4
It may not be possible to rotate 2. Therefore, when the magnetic sensor 54 detects that the toner concentration of the developer 31 has become lower than a predetermined value due to the consumption of toner according to image formation, first, the second rotation transmission mechanism 48 is operated,
The gear 49 is provided with a rotational force that tends to rotate in a rotation direction (direction shown by an arrow B shown in FIG. 5) opposite to a rotation direction of the first rotation shaft 39 (direction shown by an arrow G shown in FIG. 2). The rotation force added to the support member 67 and applied to the third screw 42 by the rotation of the first rotation shaft 39 is relieved as indicated by an arrow G in FIG. 2, and the engagement between the stopper 71 and the gear 49 is released. To do. Thus, when the stopper 71 is released from the engagement with the gear 49, the second rotation transmission mechanism 4 is released.
8 is turned off, the first rotation transmission mechanism 43 is immediately activated,
A first rotary shaft 39 as shown by arrow G in FIG.
Is applied to the support member 63, and the third screw 4
2 is rotated in the same direction as the first rotation shaft 39, and the toner supplied from the toner cartridge 20 to the toner supply port 35 by the rotation of the third screw 42 is transferred to the first rotation shaft 39 by the conveying action of the third screw 42. It is conveyed to the tip of the screw 37.

At this time, the rotation direction of the fourth screw 47 (direction shown by arrow H in FIG. 2) is the rotation direction of the third screw 42 (direction shown by arrow G in FIG. 2).
The same direction, that is, the direction opposite to the rotation direction of the second screw 38 (the direction indicated by the arrow B shown in FIG. 5). Therefore, the carrying force acts in a direction different from the carrying direction of the developer 31 by the second screw 38. As a result, while the toner is being replenished by the third screw 42, the fourth screw 47 exerts a force to convey the developer 31 to the tip of the second screw 38, and the third screw 42 replenishes the toner. The generated toner is prevented from entering the fourth screw 47 side. The toner conveyed to the tip portion of the first screw 37 is taken up by the first screw 37 and the toner concentration of the toner is lowered by the action of the first screw 37 until it reaches the first communication path 52. It is mixed with the agent 31 and is conveyed to the first communication path 52 while being stirred. The developer 31 mixed with the replenished toner is taken by the second screw 38 after passing through the first communication path 52.
By the action of the second screw 38, the second communication passage 53
The mixture is repeatedly stirred and mixed until it reaches the point of (2), and is conveyed to the second communication passage 53. The developer 31 transported to the second communication passage 53 is taken up by the first screw 37 together with the toner transported by the third screw 42 through the second communication passage 53, and further the first screw 37. The operation of stirring and mixing by and the operation of stirring and mixing by the second screw 38 are repeated. Then, the toner is supplied by the rotation of the third screw 42 until the developer 31 reaches a predetermined toner concentration.

When the third screw 42 is rotated and the replenishment of the toner into the storage chamber 33 is completed (the toner concentration of the developer 31 in the storage chamber 33 exceeds a predetermined value), the first rotation transmission mechanism 43. To stop the addition of the rotational force to the third screw 42, immediately engage the stopper 71 with the gear 49, and lock the gear 49 to lock the third screw 42.
Completely stop the rotation of.

After being used for a certain period of time, the carrier is worn out and needs to be replaced. When such a time comes, the second rotation transmission mechanism 48 is operated, the rotation of the second rotation shaft 45 is transmitted, the fourth screw 47 is rotated, and the rotation of the second rotation shaft 45 is performed. The conveyed developer 31 is taken out and discharged from the developer discharge port 36. The movement of the developer 31 at this time follows the flow of the first screw 37 → the second screw 38 → the fourth screw 47.

[0035]

According to the invention described in claim 1, when the toner concentration in the developer is higher than a predetermined value and it is not necessary to replenish the toner from the toner cartridge, the third screw is stopped. Even if the first rotating shaft rotates, the accompanying rotation phenomenon does not occur, and even if the first rotating shaft rotates, the stop mechanism for stopping the rotation of the third screw due to the accompanying rotation phenomenon is released with a small force. Can be done at.

According to the second aspect of the invention, the rotation of the third screw can be rotated in the opposite direction to the rotation of the first rotating shaft by utilizing the rotation of the second rotating shaft. The stop mechanism for stopping the rotation of the third screw can be released with a small force.

According to the third aspect of the invention, the rotation of the third screw can be rotated in the opposite direction to the rotation of the first rotating shaft by utilizing the rotation of the second rotating shaft. The stop mechanism for stopping the rotation of the third screw can be released with a small force.

According to the invention described in claim 4, the stop mechanism for stopping the rotation of the third screw can be released with a small force.

[Brief description of drawings]

FIG. 1 is a plan view of a screw portion of a developing device according to the present invention.

FIG. 2 is an enlarged cross-sectional view of the developing device illustrated in FIG.

FIG. 3 is a cross-sectional view showing an engaged state of a stopper and a gear of the developing device shown in FIG.

FIG. 4 is an overall configuration diagram of an image forming apparatus using a developing device.

5 is an enlarged sectional view of the developing device shown in FIG.

FIG. 6 is a plan view of a screw portion of the developing device illustrated in FIG.

[Explanation of symbols]

1 …………………………………………………… Image forming device 20 ……………………………………………… Toner cartridge 24 …… ……………………………………………… Casing 26 ………………………………………………… Developing roller 31 ………………………… …………………………… Developer 32 …………………………………………………… Partition plates 33, 34 …………………………………… …… Storing chamber 35 …………………………………………………… Toner supply port 36 …………………………………………………… Developer drain Outlet 37,38,42,47 ………………………… Screw 39,45 ………………………………………… Rotary shaft 41 ………………………… ……………………………… Motor 43,48 ……………………………… Rotation transmission mechanism 40,44,46,49 ………………………… Gear 50 …………………………………………………… Intermediate gear 60,61, 62,64,65,66 ………… Bearing 63,67 ………………………………………… Supporting member 70 ………………………………………… ……… Stopping mechanism 71 …………………………………………………… Stopper 72 …………………………………………………… Arm 73 …… ………………………………………………… Fixing member 74 …………………………………………………… Pin 75 ……………………… ……………………………… Solenoid body 76 …………………………………………………… Solenoid drive rod

Claims (4)

[Claims] 1. A two-component developer of toner and carrier supplied from a toner cartridge is filled in a casing of a developing device, and the casing is divided into two storage chambers by a partition plate, and the toner is stored in one storage chamber. A first screw that conveys the carrier while mixing and stirring the carrier, and a toner that is disposed on the axis of the first screw and that rotates independently of the rotation of the first screw and that is supplied from a toner cartridge. A third screw that conveys to the tip of the first screw is housed, and the other storage chamber rotates in a direction opposite to the rotation direction of the first screw in association with the first screw. A second screw that circulates the developer conveyed by the screw while stirring and a second screw that is disposed on the axis of the second screw.
Independent of the rotation of the screw of the second screw and rotates in conjunction with the third screw to convey the developer in the casing to the tip portion of the second screw, or A fourth screw that conveys the developer conveyed to the front end toward the discharge port is housed, and the toner concentration of the developer in the housing chamber where the first screw is housed becomes lower than a predetermined value. In a developing device which sometimes drives the third screw to convey the toner to the tip of the first screw, the third screw is configured so as not to rotate when the toner supply is stopped. A stop mechanism to stop the
The developing device is characterized in that the stop mechanism is released when the toner supply is started by applying a rotational force in a direction opposite to the rotational direction of the first screw to the third screw. . 2. The first screw is fixed to a first rotating shaft that is inserted through the center of the first screw, and the first rotating shaft is driven to rotate by a motor. Rotating, the second screw is
In response to transmission of rotation of the first rotating shaft, the first rotating shaft
2. The developing device according to claim 1, wherein the developing device is fixed to a second rotating shaft that rotates in a direction opposite to the rotation of the rotating shaft, and rotates in synchronization with the rotation of the second rotating shaft. 3. The first screw, which is formed in a tubular shape, is rotatably fitted to the first rotating shaft, and transmits rotation of the first rotating shaft using a clutch.
And the fourth screw is formed into a tubular shape, rotatably fitted to the second rotating shaft, and rotated in conjunction with the third screw. Whether the first rotation transmission mechanism rotates in the same direction as the rotation direction of the third screw,
Alternatively, a second rotation transmission mechanism that transmits the rotation of the second rotation shaft by using a clutch is rotated in a direction opposite to the rotation direction of the first screw. Development device. 4. The stop mechanism comprises a stopper that is attached to and detached from a gear attached to the second rotation transmission mechanism by the action of a solenoid, and the release of the stop mechanism when starting the toner supply is performed by a clutch. Then, the second rotation transmission mechanism is actuated to apply a rotation force to the fourth screw in the same direction as the rotation direction of the second rotation shaft, and then the solenoid is operated to operate the stopper engaged with the gear. The developing device according to claim 1, 2 or 3, which is adapted to be removed.