JPH03116171A - Toner replenishing device - Google Patents

Abstract

PURPOSE:To correct the unevenness of toner concentration with simple constitution by forming a slit on the bottom of a toner storing hopper and controlling the rotating position of the slit so that toner replenished quantity may be adjusted. CONSTITUTION:In the case of detecting the lack of toner by toner concentration detecting sensors 34 and 35 provided on both end parts in the axial direction of a developing roller 1, the toner is replenished from the toner storing hopper 32 through the slit 36a on the bottom. The slit 36a has such a shape that the toner can be preponderantly supplied to the axial center part or the end part of the developing roller 1 of the developing device 31 respectively according to the rotating position of a hopper 37. Therefore, the toner replenished quantity in the axial direction of the developing roller is adjusted by controlling the rotating position of the toner storing hopper 32. Thus, the unevenness of toner concentration is eliminated with simple constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a toner replenishing device for replenishing toner into a developing unit of an image forming apparatus such as a copying machine.

[Conventional technology]

An electrostatographic copying machine includes a photoreceptor on which a latent image is formed, and a developing section that develops the photoreceptor with toner. The developing section is provided with a developing device that accommodates a developing roller and the like, and a toner replenishing device that replenishes toner into the developing device.

In this toner replenishing device, various control means are provided to prevent uneven toner concentration from occurring in the axial direction of the developing roller.

For example, in the density unevenness correction device disclosed in Japanese Patent Application Laid-Open No. 63-243979, a plurality of toner density detection sensors are arranged at predetermined intervals in the axial direction of the developing roller, and the toner density detection sensors are arranged in the upper toner box. Openings are formed in correspondence with each other, and each opening is provided with a shutter.

Then, the shutter is opened and closed in accordance with information detected by the toner concentration detection sensor to correct uneven toner concentration.

[Problem to be solved by the invention]

In the prior art disclosed in the above publication, a solenoid is used to open and close the shutter. In such a device,
Solenoids are required corresponding to the number of shutters, which makes the mechanism very complex, and there is a high possibility that toner will locally solidify and fall when the shutters are opened. This may cause toner to fall on the image.

An object of the present invention is to provide a toner replenishing device that can eliminate toner density unevenness with a very simple configuration.

[Means to solve the problem]

A toner replenishing device according to the present invention replenishes toner into a developing device of an image forming apparatus. The image forming apparatus includes a plurality of toner concentration detection sensors, a toner storage hopper, and rotational position control means.

The toner concentration detection sensors are arranged at predetermined intervals in the axial direction of the developing roller. Further, the toner storage hopper is rotatably arranged above the developing device, and has a slit formed at the bottom for replenishing toner and adjusting the amount of toner replenishment in the axial direction of the developing roller. Further, the rotational position control means controls the rotational position of the toner storage hopper in accordance with the detection output of the toner concentration detection sensor.

[Effect]

In this invention, the toner concentration at each sensor position is detected by a plurality of toner concentration detection sensors provided in the axial direction of the developing roller.Normally, toner concentration unevenness occurs before and after the longitudinal direction of the developing roller. Therefore, sensors are provided at both ends of the developing roller in the axial direction. If the toner concentration detection sensor detects that there is a shortage of toner, toner is replenished from the toner storage hopper through a slit formed at its bottom. The slit of the toner storage hopper is shaped so that toner can be supplied intensively to the center, one end, or the other end of the developing roller shaft of the developing device, depending on the rotational position of the hopper.

If, for example, it is determined that there is a shortage of toner in the central portion according to the detection outputs of the plurality of toner concentration detection sensors, the toner storage is configured so that the toner is replenished intensively in the central portion. The rotational position of the hopper is controlled, and if it is determined that there is a shortage of toner at the front end or rear end, toner is supplied intensively to either end where there is a shortage. The rotational position of the toner accommodating hopper is controlled so that the toner storage hopper is rotated.

In this way, it is possible to adjust the amount of toner replenishment in the axial direction of the developing roller and eliminate unevenness in toner density.

〔Example〕

FIG. 1 shows an example in which the present invention is applied to a copying machine.

In FIG. 1, a document presser 13 is attached to the upper surface of a copying machine main body 11 so as to be openable and closable. Paper feed cassettes 14 and 15 are removably attached to the canvas side of the copying machine main body 11. A paper discharge tray 18 from which copied sheets are discharged is mounted on the left side of the copying machine main body 11 in the figure.

Inside the copying machine main body 11, an exposure device 19 for reading a document is provided on the upper side thereof. This exposure device 19 is composed of a light source, a mirror, and the like. Also,
A photosensitive drum 20 on which an electrostatic latent image is formed is arranged in the center of the copying machine main body 11. Around the photoreceptor drum 20, there are a charging device 21 that charges the photoreceptor drum 20 to a predetermined charge, a developing device 22 that develops an electrostatic latent image, a transfer device 23 that transfers the toner image onto paper, and a photoreceptor. A paper separation device 24 for separating paper from the drum 20 and a cleaning device 25 for removing residual toner on the photosensitive drum 20 are arranged.

Between the paper feed cassette 14, 15 and the image forming section constituted by the photosensitive drum 20, etc., and on the downstream side of the image forming section, there are a paper feed conveyance path 27 and a paper discharge conveyance path 28 for conveying paper, respectively. is provided. A fixing device 30 is arranged between the paper discharge conveyance path 28 and the paper discharge tray 18 to fix the transferred image on the conveyed paper.

FIG. 2 shows an enlarged view of the developing device 22. Also, the third
The figure is an exploded view of FIG. 2 viewed from the direction of the arrow ■. As shown in these figures, the developing device 22 includes a developing device 31 that houses the developing roller 1, stirring roller 2, etc. therein, and a toner storage hopper (hereinafter referred to as hopper) provided above the developing device 31. 32 and a toner cartridge 33. Toner concentration detection sensors (hereinafter referred to as toner concentration sensors) 34 and 35 are provided above the developing device 31 at the front and rear ends of the device, respectively.

The hopper 32 is connected to a replenishment pipe 36 provided along the axial direction of the developing roller 31 and to the front (right side in FIG. 3) of the developer 31. It has a toner storage section 37. The replenishment pipe 36 is rotatably supported by the toner storage section 37.

At the rear end of the supply pipe 36 (left side in Figure 3), a gear 3 is installed.
8 is fixed, and this gear 38 meshes with a pinion 40 fixed to a stepping motor 39, so that the replenishment pipe 36 can be rotated. Further, inside the replenishment pipe 36, there is a spiral 4 for conveying the toner in the toner storage section 37 in the axial direction of the developing roller.
1 is provided, and a sulin) 36a is formed at the bottom. In order to make the toner falling amount distribution uniform, the slit 36a has an opening at a position close to the side where the toner is supplied so that the toner falls when the height of the toner in the toner supply pipe 36 is relatively high. Further, an opening is formed on the rear side of the slit 36a so that the toner in the toner replenishing pipe 36 can fall even if the height thereof is low.

This copying machine also includes a control section 42 as shown in FIG. The control section 42 is connected to the toner concentration sensors 34 and 35 shown in FIGS. 2 and 3, an operation section 43 in which various keys are arranged, and other input sections.

The control unit 42 also includes a spiral drive unit 44 that includes a motor that drives the spiral 4I, and a stepping motor 3 that drives the replenishment pipe 36 shown in FIG.
9, a copy operation section 45 consisting of a motor for driving the photosensitive drum 20, etc., and other output sections are connected. This control unit 42 includes a CPU and a ROM.

Equipped with a microcomputer consisting of RAM, etc.
Control the device as follows.

Next, the operation of this embodiment will be explained according to the control flow shown in FIGS. 5A to 5C.

When the main switch (not shown) is turned on, first, in step 31, the number of copies is set to one, the heater of the fixing section is turned on, and the stirring roller 2 in the developing device 31 is set.
Initial settings such as driving are performed. Next step S
2, it is determined whether the toner density (T/D) of each part is equal to or higher than a predetermined value. This determination is made based on the output signals of the toner concentration sensors 34 and 35. If it is determined in step S2 that the toner density is below the reference value, the process moves to step S3. In this step S3, a toner density control subroutine to be described later is executed.

In step S4, completion of the copy preparation operation is awaited. When the preparation is completed, the process moves to step S5, and it is determined whether the print key has been pressed. If the print key has not been pressed, the process moves to step S6, and it is determined whether or not another input key has been pressed.

If another key is pressed, the process moves to step S8,
Processing corresponding thereto is executed and the process returns to step S5.

When the print key is pressed, the process moves from step S5 to step S7. In step S7, a copy operation subroutine shown in FIG. 5B is executed.

In FIG. 5B, in step S9, the photosensitive drum 2
The copying operation is started by rotating the 0 or by starting the exposure device 19.

In step SIO, it is determined whether the toner density of each part is equal to or higher than a predetermined density. Executes the toner density control subroutine that indicates insufficient toner.

Also, in step 512, other subroutines required during the copying operation are executed. And step S1
In step 3, it is determined whether the copying operation has been completed. If the copying operation has not been completed, the process returns to step S10. That is, while the copying machine is performing a copying operation, step S
The processing from IO to step 317 is repeated. When the copying operation is completed, the process returns to the main routine of FIG. 5A from step S13.

Next, the toner density control subroutine executed in step S3 and step Sll will be described.

In FIG. 5C, in step S14, it is determined whether the stirring roller 2 is rotating. In toner concentration control, it is necessary that the developer in the developing device 31 is stirred, so if the stirring roller 2 is not rotating for some reason, the process moves to step S15 and the stirring roller 2 is rotated.
Rotate.

Next, in step S16, the toner in the toner storage section 37 is conveyed in the axial direction of the developing roller 1 (the spiral 41 starts rotating). It is determined whether the front and back are the same.This determination is made based on the detection output T of the toner concentration sensor 34.
The detection output T2 of the toner concentration sensor 35 is compared with l and the detection output T2 of the toner concentration sensor 35 is compared, and this is performed depending on whether the difference between them is less than a predetermined value (O in this case). If it is below the predetermined value, the process moves to step S18. In step 31B, the hopper replenishment pipe 36 is brought to a reference position as shown in FIG. 6A. In the rotational position shown in FIG. 6A, the slit 36a is positioned so that when the toner is conveyed horizontally within the replenishment pipe 36, the distribution of the amount of toner falling in the axial direction of the developing roller becomes uniform.

On the other hand, if it is determined in step S17 that there is a difference between the toner density before and after, the process moves to step S19.

In step S19, it is determined in which direction of the front and rear directions the toner density is higher.

If it is determined that the toner concentration in the front part is higher, the process moves to step S21, and the replenishment pipe 36 is rotated in the direction of arrow B in FIG.
The rotation is controlled so that a is at the position shown in FIG. 6B. As a result, the amount of toner falling on the rear side increases, and unevenness in toner concentration is eliminated. Conversely, if it is determined that the rear 1-ner density is higher, step 52
Transition to 0. In step S20, the replenishment pipe 36 is rotated in the six directions of the arrows in FIG. 3 in the opposite direction to the above.

As a result, the slit 36a of the toner supply pipe 36
is in a position as shown in FIG. 6C. As a result, the amount of toner falling at the front portion increases, and unevenness in toner concentration is eliminated.

Next, in step S22, it is determined whether the toner density has exceeded a reference value. If the reference value is insufficient, the process moves to step S24. In step 324, it is determined whether the toner in the hopper including the toner cartridge is empty. If the determination in step S24 is No, the process returns to step 317, and the aforementioned toner supply amount adjustment operation is repeated.

If it is determined in step 324 that the toner is empty, the process moves to step S25, and an empty display is displayed on the operation unit 43. Then, the process moves to step S26 to stop the apparatus and return to the routine shown in FIG. 5A or FIG. 5B.

Further, if it is determined in step S22 that the toner concentration has become equal to or higher than the reference value, the process moves to step S23, and the rotation of the spiral 41 is stopped. Then, the process returns to the routine shown in FIG. 5A or 5B.

[Other Examples]

(a) In the embodiment described above, the toner cartridge 33 and the toner accommodating portion 34 of the hopper are provided at the front of the apparatus, and the toner is conveyed from there in the axial direction of the developing roller through the replenishing pipe 36, and the toner is transferred into the developing device 31. Although the present invention has been applied to a developing device for replenishing the developing device, the present invention is also applicable to a device that provides a toner accommodating portion of a toner hopper above the developing device 31 and replenishes the toner inside the developing device 31 by dropping toner from above. can.

In this case, a slit 50a as shown in FIGS. 7A to 7C may be provided at the bottom of the toner hopper 50, and the amount of toner supplied may be adjusted by controlling the rotational position of this slit 50a. .

Note that FIGS. 7A to 7C are bottom views of the toner hoverer, respectively. FIG. 7A shows the rotational position of the slit 50a when the toner distribution is uniform, and FIG. If there is a shortage, Figure 7C shows each slit 5 when the rear toner concentration is insufficient.
The rotational position of 0a is shown.

(b) In the above embodiments, the present invention is applied to a developing device of a copying machine, but it can be similarly applied to a developing device of other devices such as a laser printer.

〔Effect of the invention〕

As described above, in the present invention, a slit is formed at the bottom of the toner storage hopper, and the rotational position of this slit is controlled to adjust the amount of toner replenishment.
It is possible to correct uneven toner density with a simple structure.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional configuration diagram of a copying machine employing a toner replenishing device according to an embodiment of the present invention, FIG. 2 is an enlarged view of its developing device, and FIG. , FIG. 4 is a control block diagram of the copying machine, FIGS. 5A to 5C are control flowcharts of the apparatus of the embodiment, and FIGS. 6A to 6C are diagrams showing rotation control positions of the toner supply pipe. 7A
7C are diagrams showing other embodiments of the present invention. 34.35... Toner concentration detection sensor, 3G... Supply pipe, 36a... Slit, 37... Toner storage section, 38... Gear, 39... Stepping motor, 40... Pinion, 42...Control unit, 50...
・Toner hopper 50a...slit.

Claims (1)

[Claims] (1) A toner replenishment device that replenishes toner into a developing device of an image forming apparatus, which includes a plurality of toner concentration detection sensors arranged at predetermined intervals in the axial direction of a developing roller, and rotatably arranged above the developing device. a toner accommodating hopper having a slit formed at the bottom for replenishing toner and adjusting the amount of toner replenishment in the axial direction of the developing roller; A toner replenishing device comprising: a rotational position control means for controlling the position;