JPH10207238A - Driving method for developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the driving method of a bucket roller type developing device by which the stirring property of replenishing toner is enhanced and toner fogging is eliminated. SOLUTION: By this method, two-component developer consisting of toner and carrier is drawn up while being stirred, passed through a levelling plate 15 and supplied to developing rollers 23 and 25 by rotating a bucket roller 10 in a direction shown by an arrow (a). Then, the toner is linearly replenished to the upper part of the roller 10 and on the upstream side of the plate 15 in parallel with in the shaft direction of the roller 10 from the replenishing roller 33 of a toner replenishing part 30. When the developing actions of 100 or more sheets of images are finished by continuously driving the rollers 10, 23 and 25, the driving of the rollers 10, 23 and 25 is stopped once. Thereafter, at least the roller 10 is driven in prescribed time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for driving a developing device, and more particularly, to a developing method for visualizing a latent image formed on an image carrier, which is incorporated in an electrophotographic copying machine or a laser printer. The present invention relates to a method for driving the device.

[0002]

2. Description of the Related Art Some developing devices used in an electrophotographic image forming process use a two-component developer composed of a toner and a carrier. In such a developing device, the developing roller and the developer stirring member are continuously driven during the copying operation,
Even after the development is completed, control for driving (stirring) is performed for a certain period of time. The reason for continuing the drive after the development is
This is because if the newly supplied toner is not sufficiently agitated, charging failure will occur, and toner fogging on the image background will occur.

Further, as a measure for improving the toner agitation property, Japanese Utility Model Laid-Open No. 4-67658 discloses that the driving time of the developing device is extended when the document density is high (the toner replenishment amount increases). It has been disclosed. Also, Japanese Unexamined Patent Publication No.
Japanese Patent Laid-Open No. 249827 discloses that the driving time of the developing device is changed according to the toner supply time.

[0004]

However, the two-component developer is pumped up while being stirred based on the rotation of the bucket roller, supplied to the developing roller by passing through the developer sliding member, and the toner is wiped by the sliding member. In a system in which the toner is replenished in a line from above the bucket roller parallel to the rotation axis direction of the roller on the upstream side of the roller (hereinafter, referred to as a bucket roller system), the toner replenished during continuous driving is a sliding member. Stays upstream of the vessel with insufficient stirring. As the number of continuous copies increases, the total amount of toner replenishment during the copy operation also increases, and the retention of insufficiently stirred toner increases. Such insufficiently stirred toner is formed into a minute lump, and falls into the developer tank from the gap between the bucket rollers when the driving of the developing device is stopped. When the next copy operation is started, such insufficiently stirred toner is pumped up by the bucket roller and supplied to the developing roller, and toner fogging occurs.

SUMMARY OF THE INVENTION An object of the present invention is to provide a driving method of a developing device of a so-called bucket roller type developing device, which can improve the agitation of replenishment toner and can eliminate toner fogging.

[0006]

SUMMARY OF THE INVENTION To achieve the above object, the present invention relates to a method of driving a developing device of a bucket roller type, wherein a bucket roller and a developing roller are continuously driven to develop a predetermined number of images or more. Upon completion, the driving of the bucket roller and the developing roller is temporarily stopped, and thereafter, at least the bucket roller is driven for a predetermined time.

According to the above-described driving method, when the driving of the bucket roller is temporarily stopped at the end of the developing operation, the toner remaining on the upstream side of the sliding member during the copying operation is removed from the gap of the bucket roller by the developer. Fall into the tank. Thereafter, the staying toner is stirred and mixed with the carrier by driving the bucket roller for a predetermined time. At the time of this re-driving, toner supply is not performed, so that new toner with insufficient stirring does not occur.Moreover, the staying toner is charged by stirring, and the toner with insufficient stirring is applied to the image background during the next development. It is possible to prevent a problem such as wearing.

Further, the staying toner is generated when the developing device is driven for a relatively long time. In the present invention, the re-driving of the developing device is executed when the development of a predetermined number of images or more is completed. I decided to do it. Accordingly, since re-driving is omitted during a relatively short developing operation in which there is no possibility of generation of staying toner, the load on the apparatus can be reduced, and the waiting time for the next copying operation can be shortened.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for driving a developing device according to the present invention will be described below with reference to the accompanying drawings. In FIG. 1, a developing device includes a developer tank 1, a bucket roller 10, a supply roller 21, and a first developing roller 2.
3, a second developing roller 25, and a toner supply unit 30.

The bucket roller 10 has a conveying member 12 and a stirring blade 13 mounted around a rotation shaft 11 and is installed so as to be rotatable in the direction of arrow a in the developer tank 1. As the developer D, a well-known two-component developer composed of a toner and a carrier is used.
3 and moves in the axial direction while being stirred.
It is pumped up by 2 and transported in the direction of arrow a. A part of the developer moving in the axial direction by the stirring blade 13 enters the circulation passage 2 formed in the upper right portion of the developer tank 1, and the screw 5 conveys / stirs the inside of the passage 2 in the axial direction of the screw 5. Is returned to the developer tank 1 again. A magnetic sensor 6 for detecting the toner concentration of the developer is provided on the bottom of the circulation passage 2. When the sensor 6 detects that the toner concentration has dropped below the reference value, a toner replenishment command is issued. .

The supply roller 21, the first developing roller 23, and the second developing roller 25 are provided with a plurality of permanent magnets 22,
24, 26, with arrows b, c, d respectively
It can be driven to rotate in the direction. Permanent magnet 22,2
4 and 26 have magnetic poles at the positions shown in FIG. 1 and do not rotate.

The developer D conveyed in the direction of arrow a by the conveying member 12 of the bucket roller 10
5, is attracted and held on the outer peripheral surface of the supply roller 21 by the magnetic force of the permanent magnet 22, conveyed in the direction of arrow b with the rotation of the supply roller 21, and supplied to the outer peripheral surface of the first developing roller 23. Is done. At this time, the developer is
The transport amount is regulated by Thereafter, the developer is transported in the direction of arrow c with the rotation of the first developing roller 23, further transported in the direction of arrow d with the rotation of the second developing roller 25, and returned to the developer tank 1. A photoreceptor drum (not shown) is provided with a predetermined gap from the developing rollers 23 and 25, and the electrostatic latent image is developed by the developer at the N pole portion of the permanent magnet 24 and the S pole portion of the permanent magnet 26. Will be

Reference numeral 27 denotes a partition plate, reference numeral 28 denotes a toner dust prevention member, and reference numeral 29 denotes a sealing material made of a resin film.

On the other hand, the toner replenishing section 30 comprises a toner conveying screw 31, a stirring lever 32, and a toner replenishing roller 33 made of a sponge material. Supply unit 30
A toner replenishing bottle (not shown) is removably provided directly above the toner. The toner is replenished from the bottle onto the screw 31 based on the toner concentration detection signal of the magnetic sensor 6, and the stirring lever 32 is rotated by the rotation of the screw 31.
Transported to the side. Further, the toner is conveyed to the replenishing roller 33 side by the rotation of the stirring lever 32, and is supplied from the replenishing roller 33 onto the bucket roller 10 on the upstream side of the slicing plate 15 in a direction parallel to the rotation shaft 11. Will be replenished.

In the developing device having the above configuration, the rollers 10, 21, 23, 25 and the screw 5 are continuously driven to rotate during the copying operation, and the toner supplied from the supply roller 33 is rotating. Bucket roller 1
0 falls on the layer of developer D formed by the zero. Then, it is rubbed off by a rubbing plate 15 located on the downstream side of the drop part D ₁ ,
Falling inside. However, all of the toner that has reached the slicing plate 15 is slashed and does not fall, and a portion of the toner T remains as a minute lump. As the number of continuous copies increases, the amount of staying toner T also increases. The stagnant toner T is insufficiently agitated. When the copy operation is completed and the driving of the developing device is stopped, the stagnant toner T falls into the bucket roller 10 from the gap of the transport member 12. In this case, if the developing device is set in a stopped state as it is, insufficient stirring (charging) of the toner will cover the background of the first image in the next copy operation.

Therefore, in the first embodiment, FIG.
As shown in FIG. 7, when the developing device is continuously driven to develop an image of less than 100 sheets, as a normal control, the developing device (the rollers 10 and 21) is operated after a lapse of a certain time Ta after the end of the development of the final copy. , 23, 25, screw 5)
To stop driving. Such control is the same as the conventional control. In this case, the staying toner T does not exist so much.
This is because there is no possibility that toner fogging will occur on the background portion of the image.

On the other hand, by continuously driving the developing device, 100
When more than one image has been developed, the drive of the developing device (rollers 10, 21, 23, 25, screw 5) is temporarily stopped for a time Tb when a certain time Ta has elapsed after the development of the final copy has been completed, Thereafter, the developing device is driven for a time Tc. When the number of continuous copies increases, the amount of staying toner T increases as described above.
During the re-driving time Tc, the toner falls into the bucket roller 10 and is stirred and charged. Accordingly, the fogging of the toner on the image background portion at the next copy processing of the first sheet is prevented.

FIG. 2B shows a second embodiment. The developing device is provided with rollers 21, 23, 25
The screw 5 can be turned on and off by one clutch, and the bucket roller 10 can be turned on and off independently by another clutch. The control when the developing device is continuously driven to develop less than 100 images is the same as that in the upper part of FIG. 100
If the number of sheets is equal to or more than the number of sheets, as shown in FIG.
23, 25, the rotation of the screw 5 and the bucket roller 10 are stopped. Then, after the time Tb has elapsed, the bucket roller 10 is driven alone for the time Tc.

FIG. 3 shows an operation panel 5 installed on a copying machine.
Indicates 0. On the operation panel 50, a liquid crystal touch panel 51, a numeric keypad 52 for inputting the number of copies and a copy magnification, a clear key 53 for resetting the input on the numeric keypad 52, various copy modes and the like are reset to an initial setting state. Key 54, a stop key 55 for interrupting the copy operation, and a start key 56 for starting the copy operation. Further, on the operation panel 50, various copy mode selection keys for setting a copy mode in combination with an automatic document feeder, a finisher, and the like, and display LEDs are provided.

FIG. 4 shows a main part of a control circuit of the copying machine. The control is executed mainly by the CPU 60. The CPU 60 receives signals from various input means on the operation panel 50 and outputs signals for display. The CPU 60 includes the bucket roller 10, the supply roller 21, the developing rollers 23 and 2,
5 and the developing motor M1 for driving the screw 5, and the toner supply motor M2 for driving the screw 31, the lever 32 and the supply roller 33 are controlled. Further, a toner density detection signal from the magnetic sensor 6 is input to the CPU 60.

FIG. 5 shows the outline of the control procedure of the developing process by the CPU 60. First, when the start of the copying operation is confirmed in step S1, the developing motor M1 is started in step S2.
Turn on. This starts the driving of the bucket roller 10, the developing rollers 23 and 25, and the like. During the copying operation, if it is confirmed in step S3 that a toner replenishment command has been issued, toner replenishment is executed in step S4. Next, step S5
When the end of development of the final copy is confirmed in step S6,
Waits for the time Ta to elapse, and turns off the developing motor M1 in step S7. With this, the bucket roller 10,
The driving of the developing rollers 23 and 25 is temporarily stopped.

Next, in step S8, it is determined whether or not the number of copies in the current series of copy operations is 100 or more. 1
If it is not less than 00, the process waits for the time Tb to elapse in step S9, and turns on the developing motor M1 in step S10. Thus, the bucket roller 10, the developing roller 23,
25 and the like are driven again. Further, after waiting for the elapse of time Tc in step S11, the developing motor M1 is started in step S12.
Turn off.

The driving method of the developing device according to the present invention is not limited to the above embodiment, but can be variously changed within the scope of the invention. In particular, it goes without saying that various configurations and shapes other than those shown in FIG. 1 can be used as the configuration of the developing device, and one developing roller may be used. .

[Brief description of the drawings]

FIG. 1 is a sectional view showing a developing device to which a driving method according to the present invention is applied.

FIGS. 2A and 2B are time charts showing a driving method according to the present invention, wherein FIG. 2A shows a first embodiment and FIG. 2B shows a second embodiment.

FIG. 3 is a plan view showing an operation panel of the copying machine.

FIG. 4 is a block diagram showing a main part of a control circuit of the copying machine.

FIG. 5 is a flowchart illustrating a control procedure as a first embodiment in a developing process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Developer tank 10 ... Bucket roller 15 ... Developer slicing plate 23, 25 ... Developing roller 60 ... CPU M1 ... Developing motor D ... Developer T ... Stagnant toner

Claims (1)

[Claims] 1. A two-component developer comprising a toner and a carrier is pumped up while being stirred based on the rotation of a bucket roller, supplied to a developing roller by passing through a developer sliding-off member, and is supplied to the developing roller. In a driving method of a developing device for supplying a line from above a bucket roller on an upstream side in parallel with a rotation axis direction of the roller, the bucket roller and the development roller are continuously driven to develop a predetermined number of images or more. When the driving is completed, the driving of the bucket roller and the developing roller is temporarily stopped, and then at least the bucket roller is driven for a predetermined time.