JPS6134568A - Toner feeding device - Google Patents

Abstract

PURPOSE:To ensure the feeding of toner, by displaying that the toner to be fed is exhausted through a toner end displaying means when a condition where the toner concn. detected by a toner concn. detecting means does not reach the 2nd prescribed level continues for a prescribed time or longer. CONSTITUTION:A main control circuit 30 is composed of a microcomputer, etc., and communicates signals with the external control section 31 of each motor, clutch, lamp, etc., for making copying operations, operation displaying section 32 making various displaying operations, such as the set numbers of copying papers, etc., and toner feeding and toner end display controlling circuit 33, and so forth. The controlling circuit 33 discriminates the toner concn. in accordance with the detected output of a toner concn. detector 16 and controls the drive of a toner feeding motor 24 from the discriminated result. The controlling circuit 33 also acts as a toner end display controlling means in such a way that, when the toner to be fed is exhausted, the circuit 33 detects that and causes the operation displaying section 32 to display that no toner exists through the main control circuit 30.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a toner replenishing device for replenishing toner to a developing device using a two-component developer such as an electrophotographic copying machine.

In a developing device that uses a two-component developer, such as an electrophotographic copying machine, it is necessary to replenish toner to keep the toner concentration of the developer constant.

To detect the remaining amount of toner for replenishment, for example, there is a method of directly detecting the amount of toner in a toner hopper (storage device) in a toner replenishing device using a toner remaining amount detection element. Since it is necessary to attach elements and install a detection circuit, the device becomes complicated and costs increase.

Therefore, as a simple method, when the replenishment operation by the toner replenishing device continues for a predetermined time or a predetermined number of times, it is assumed that the toner in the toner hopper is exhausted, and a display indicating that there is no toner is available.

However, with this method, if you continue to make a large number of copies that consume more toner than the toner replenishment amount (for example, copies of photographs or negative images), toner replenishment will continue, and the hopper will need to be refilled. Even though there is enough toner left in the printer, it may be mistakenly detected that there is no more toner to replenish.

However, if you replenish toner in excess of the maximum toner consumption to avoid this, the agitation performance within the developing device is limited, resulting in excess toner in some areas, causing problems such as image fogging and toner scattering inside the machine. .

This invention was made by focusing on the problems mentioned above, and there are fewer problems such as false detection and insufficient stirring, and it is a simple and reliable way to replenish toner and when the toner runs out. It is an object of the present invention to provide a toner replenishing device capable of displaying the above information.

1-Admission Hereinafter, the configuration of the present invention will be explained based on one embodiment.

FIG. 1 is a schematic sectional view of a developing device of a copying machine to which the present invention is applied, and its structure and operation will be explained.

In the developing device 1, a two-component developer 3 consisting of carrier and toner stored in the lower part of a developing tank 2 is pumped up by pumping sleeves 6 and 8, each having a plurality of magnets 5 and 7 fixed therein. The magnets S are delivered to a developing sleeve 10 which is fixedly installed.

Then, a magnetic brush is formed by the developing sleeve 10 to cause the developer to adhere to the photoreceptor drum 11, and after the electrostatic latent image is developed and visualized with the toner, a developed image with a reduced toner concentration is transferred from the developing sleeve 10. Separator 12
The toner is separated and dropped into the toner supply pipe 13 or stirring pipe 14.

At this time, the developer that has fallen into the toner supply pipe 13 is
The toner is returned into the developing tank 2 together with the replenishment toner conveyed by the replenishment screw 15 .

Further, within the developing device 1, a toner concentration detector 16 is provided which allows a portion of the developer separated from the developing sleeve 10 by the separator 12 to pass therethrough and detects the toner concentration thereof.

This toner concentration detector 16 is a known one that utilizes the fact that the impedance of the coil changes depending on the change in the toner concentration of the developer flowing down inside the coil provided inside.

Note that the developer that has fallen into the developing tank 2 and the toner that has been supplied from the toner supply pipe 13 are uniformly stirred by a screw agitator 18 that is a stirring member.

- Next, the structure and operation of the toner replenishing section that replenishes toner into the developing tank 2 will be explained with reference to FIG.

A toner replenishment pipe 1 is provided with a protruding end portion 21a bent laterally at the lower end of a toner hopper 21 that stores replenishment toner 20, and is installed between a front side plate 22 and a rear side plate 23 of the developing device.
It is connected to one end of 3.

This toner supply pipe 13 and toner hopper 2
A replenishment screw 15 is provided so as to penetrate through the inside of the protruding end portion 21a.

A large number of through holes 13a for developer inflow are arranged in the upper part of the toner replenishment pipe 13, and a large number of through holes 13b for developer and replenishment toner outflow are arranged in a row at the lower part.

On the other hand, below the toner hopper 21 is a plate 25 with a toner supply motor 24 attached to the side of the toner hopper 21.
The above-mentioned supply screw 15 is made to protrude from the plate 25, and a gear 26 is attached to the protruding end thereof, and a gear 27 is attached to the rotating shaft 24a of this motor 24.
It meshes with.

Therefore, when the toner replenishment motor 24 is driven, the replenishment screw 15 rotates via the gears 27 and 26, and the i.
Transfer the toner 20 in the inner tube 21 to the toner auxiliary M pipe 13.
and then further conveyed to the left in the figure. The driving of the toner replenishment motor 24 is controlled by a toner replenishment/toner end display control circuit 33, which will be described later.

The toner conveyed through the toner replenishment pipe 13 falls through the opening of the separator 12 shown in FIG. The through hole 13b formed at the bottom mixes with the developer flowing in from the
The developer flows out from the developer tank 2 and is replenished into the developer tank 2.

A large-diameter hole 13c is formed on the lower surface of the end of the toner supply pipe 13 near the rear plate 23 to prevent toner and developer from accumulating at the end.

FIG. 3 is a block diagram showing a control system of a copying machine to which the present invention is applied.

The main control circuit 30 is a circuit that controls the entire copying machine, and is composed of a microcomputer, etc., and controls each motor, clutch, and lamp for copying operations.

an external control unit 31 such as a sensor; an operation display unit 32 that performs various operations such as setting the number of copies and starting copying; and various displays including a toner end display as illustrated in FIG.
and a toner supply/toner end display control circuit 33, respectively.

The toner supply/toner end display control circuit 33 is.

The toner concentration is determined based on the detection output from the toner concentration detector 1, and the drive of the toner supply motor 24 is controlled according to the determined toner concentration, and the copy speed is switched between the normal copy speed and a slower copy speed. It serves as a toner replenishment control means and a toner end display control means that detects when toner to be replenished runs out and displays on the operation display section 32 through the main control circuit 30 that there is no toner. It is a circuit that can be configured using a microcomputer.

Next, the operation of the toner replenishment/toner end display control circuit 33 in the first embodiment of the invention will be explained in more detail with reference to the flowchart of FIG.

First, in step 1, the toner concentration TCx determined by the detection output from the toner concentration detector 16 is compared with a first predetermined level TC1 corresponding to an appropriate toner concentration that does not require toner replenishment, and it is determined that T'Cx≧TC1. If so, do not replenish toner. That is, the toner supply motor 24 is not driven.

If the toner concentration TCx is not equal to or higher than the first predetermined level TCI, proceed to step 2 and set the toner 1 concentration TCX to the first predetermined level TCI.
A second predetermined level TC,2 lower than the predetermined level TC5 of
(Te3 <TCt).

If TCX≧TC2, the process advances to step 3, where the toner replenishment motor 24 is driven to replenish toner while copying at the normal copying speed, and the toner concentration TC
If x is not greater than this second predetermined level 102, then
Proceeding to step 4, a signal is sent to the main control circuit 30 of FIG. 3 to control the copying speed to be slower than the normal copying speed, and to drive the toner replenishment motor 24 to replenish toner.

By slowing down the copy speed when replenishing toner in this way, the amount of toner consumed per unit time is reduced, which is essentially the same as increasing the amount of toner replenishment, reducing toner consumption for photographs, negative images, etc. Even when copying a large number of originals, it is possible to increase the toner density.

Note that the amount of toner replenishment in steps 3 and 4 can be controlled by the drive time or rotational speed of the toner replenishment motor 24, but this replenishment amount needs to be an amount that does not cause insufficient stirring even if the toner is continuously replenished. For example, the replenishment operation is performed intermittently at every predetermined replenishment cycle (corresponding to a copy cycle, for example).

Next, in step 5, the time Tx during which the detected toner concentration value TCX remains less than the second predetermined level TC2 (determination in step 2 becomes No) is compared with a preset time To. When Tx≧To, a signal is sent to the main control circuit 30 shown in FIG. 3, causing the operation display unit 32 to display the toner end display as shown in FIG. 4, and at the same time stopping the copying operation and starting copying. Lights up the key in red to prohibit further copying.

Initially, since Tx<To, the process returns to step 1, and steps 1 to 5 are returned to green again. However, while there is replenishment toner 20 in the toner hopper 21 in FIG. 2, toner is replenished at a slower copy speed than usual in step 4. Therefore, the toner concentration TCx gradually increases, and TCx≧TC in step 2.
The decision in step 2 will be YES and you will be able to proceed to step 3.

Toner end is never displayed.

However, when the replenishment toner 20 in the toner hopper 21 runs out, toner is not replenished even if the toner replenishment motor 24 is driven in step 4, so the toner concentration T C
x becomes larger (as the copy operation is performed, it becomes smaller due to the consumption of Lf toner), the judgment of TCx≧TC2 in step 2 remains NO, and the duration time Tx eventually becomes the set time 10 or more, so When the determination of Tx≧To in step 5 becomes YES, the toner end display and the copy operation are stopped and prohibited.

Next, the operation of the toner replenishment/toner end display control circuit 33 in the second embodiment of the invention will be explained with reference to the flowchart of FIG.

First, in step 11, as in the case of FIG. 5, the detected value TCx of the toner concentration is compared with a first predetermined level TC, and if TCx≧TC1, toner replenishment is not performed.

When the toner concentration TCx is no longer equal to or higher than the first predetermined level TC, the process proceeds to step 12, where it is determined whether the number of copies CX from that point onwards has reached a preset predetermined number Go. Until this happens, toner is replenished at the normal copying speed in step 13, and the process returns to step 11.

If it is determined in step 12 that the number of copies CX has reached the predetermined number co, the process proceeds to step 14 and the number of copies G
After calculating and storing the rate of change ΔTC in the toner concentration TCX per o, the counter for the number of copies CX is reset in step 15. - Then, in step 16, the detected toner concentration value TCX at that time is set to a second predetermined level 7r C2 (Te3 < TCI
). As a result, if TCX≧TC2, the process advances to step 13 to continue toner replenishment and supply at the normal copying speed, and then returns to step 11.

In this way, while toner is being replenished at the normal copying speed, the rate of change in toner density is calculated every predetermined number of copies co, and the stored value is updated.

If it is determined in step 16 that the toner concentration T C,

Then, the number of copies CY from that point onwards becomes a predetermined number of copies Go.
(same as C8 in step 12), the process proceeds from step 18 to step 19, where TC2 is calculated and stored as the rate of change in toner density per the predetermined number of sheets Go.

Next, in step 20, the toner concentration change rate TC1 that was last stored during toner replenishment at a normal copying speed is compared with the toner concentration change rate ΔTC2 stored in step 19, and if the two are substantially equal, the toner to be replenished is determined. It is determined that the main control circuit 30 of FIG.
A signal is sent to the operation display section 32 to display a toner end display as shown in FIG. 4, and at the same time, stop or prohibit the copying operation.

That is, the judgment in step 16 becomes NO when the donor concentration has decreased, but if there is toner to be replenished, if the toner is replenished by slowing down the copying speed in step 17, the result will be substantially lower. Since this is equivalent to an increase in the amount of toner replenishment, the rate of change in toner concentration (rate of decrease in this case) should be smaller, so it becomes ΔTC,)8TC2.

However, if there is no toner to replenish, no toner will be replenished at any time of replenishment, so the toner density will decrease by the amount of toner consumed by making copies, and the rate of change per unit number of copies will be approximately constant. From, ΔTc,
=ΔTC2.

By the way, the amount of toner to be replenished must be less than the agitation limit in the developing device 1 shown in FIG. Even if the toner is replenished, the toner density may not recover.

Therefore, in this embodiment, in consideration of such a case, when the judgment in step 20 is NO, that is, when it is judged that the two change rates are different and there is toner to be replenished, the toner concentration TCX is changed in step 22. It is determined whether the elapsed time TX after the second predetermined level TC2 is no longer reached has reached a preset predetermined time T3, and the process returns to step 16 until the predetermined time T3, and the normal Continue toner replenishment at a slower copy speed.

If the elapsed time TX is equal to or longer than the predetermined time 13, the image forming operation for copying is stopped in step 23, and toner is replenished only for a predetermined time T4.

In step 24, it is determined whether this image forming operation stop time TZ has exceeded a predetermined time T4.

In this way, during the predetermined time T4, there is no toner consumption and only toner replenishment is performed, so that the toner concentration increases and quickly recovers to the second predetermined level or higher.

Effects As explained above, both the toner replenishing devices according to the first and second inventions can replenish an appropriate amount of toner according to the toner concentration of the developer in the developing tank, and can prevent toner from leaving the toner hopper. ≧, it is possible to display the absence of toner by a simple means.

Moreover, insufficient agitation may occur due to excessive toner supply,
There is almost no possibility that an erroneous display of out of toner is displayed even though there is still toner to be replenished.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a developing device of a copying machine to which the present invention is applied; FIG. 2 is a cross-sectional view showing the structure of a toner replenishing section thereof; FIG. FIG. 4 is a block diagram showing the control system of the copying machine; FIG. 4 is a diagram showing an example of toner end display; FIG. 5 is a diagram showing the operation of the toner replenishment/toner end display control circuit in the embodiment of the first invention. Flowchart FIG. 6 is a flowchart similar to FIG. 5 in the second embodiment of the invention. 1...Developing device 2...Developing tank 3...
Two-component developer 13... Toner supply pipe 15...
- Replenishment screw 16... Toner replenishment motor 20... Replenishment toner 21... Toner hopper 24... Toner replenishment motor 30... Main control circuit 32... Operation display section 33.
...Toner replenishment/toner end display control circuit Fig. 3 Fig. 5

Claims (1)

[Scope of Claims] 1. Toner concentration detection means for detecting the toner concentration of a developer in a developing device that uses a two-component developer containing a mixture of toner and carrier; and toner replenishing means for replenishing toner to the developing device. , a toner end display means for displaying that there is no toner to be replenished in the replenishment means, and toner is not replenished when the toner concentration detected by the toner concentration detection means is equal to or higher than a first predetermined level; When the level is between the first predetermined level and a second predetermined level lower than the first predetermined level, toner is replenished at a normal copying speed, and when the second predetermined level is not reached, the copying speed is made slower than the normal copying speed. toner replenishment control means for controlling the copying speed and the toner replenishment means so as to replenish toner; and a state in advance in which the toner concentration detected by the toner concentration detection means is less than the second predetermined level. A toner replenishing device comprising: toner end display control means for causing the toner end display means to display that there is no toner to be replenished when the toner replenishment continues for a set predetermined time or a predetermined number of copies. 2. Toner concentration detection means for detecting the toner concentration of a developer in a developing device that uses a two-component developer containing a mixture of toner and carrier; toner replenishing means for replenishing toner to the developing device; and toner replenishing means for replenishing toner to the replenishing means. When the toner concentration detected by the toner end display means and the toner concentration detection means is equal to or higher than a first predetermined level, toner is not replenished, and a lower second predetermined level, toner is replenished at the normal copy speed, and when the second predetermined level is lower than the second predetermined level, the copy speed is made slower than the normal copy speed and toner is replenished. a toner replenishment control means for controlling the copying speed and the toner replenishment means, and when the copying speed during toner replenishment is changed from a normal speed to a speed slower than normal by the means, the unit before and after the change; Comparing the rate of change in toner density per number of copies,
A toner replenishing device comprising: toner end display control means for causing the toner end display means to display that there is no toner to be replenished when both rates of change are substantially equal.