JPH04174475A - Toner density controlling device - Google Patents

Abstract

PURPOSE:To detect and display toner being empty speedily and securely by providing a determining means to determine that toner inside a toner cartridge is empty when a condition of a change value of a toner sensor output of more than a predetermined value is continued for more than a preset number of times. CONSTITUTION:A CPU 10 reads a detection output V of a toner sensor 24 at a time interval (t), a change value V1, V2, V3...Vn for the detection output V at the time interval (t) is calculated, and a toner being empty for a toner cartridge 8 is detected based on the change value. In this detection mode, the change value for the detection output V is thus calculated at the time interval (t), and a rizing gradient of the change values is monitored to determine the toner cartridge 8 being empty, so a consumption condition of toner 9 in the toner cartridge 8 can be grasped precisely. The toner being empty can thus be detected and displayed speedily and securely.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention detects the toner concentration in a two-component developer made by mixing toner and hand-held liquid with a toner sensor, and uses the detection result of the toner sensor to Regarding a toner density control device that replenishes toner in a toner cartridge into a developing device based on
More specifically, it relates to a toner density control device that can accurately detect when the toner in a toner cartridge is empty.

(Prior Art) As an example of a developing device for a copying machine, a two-component developer consisting of a mixture of toner and carrier is used as the developer, and the toner is triboelectrically charged by stirring the developer and transferred to a developing sleeve. Some devices perform the development process by supplying the electrostatic latent image on the photosensitive drum through the electrostatic latent image. According to such a developing process, as the number of copies increases, toner is consumed and the toner concentration in the developer decreases, so if this condition is left untreated, a problem occurs in which the image density decreases.

Therefore, in this type of developing device, the toner concentration in the developer is detected by the toner sensor, and then the control device compares the detection signal (voltage signal) of the toner sensor with a predetermined reference voltage signal, and the comparison result is When it is determined that the toner density is lower than the reference value, the toner replenishment mechanism is driven to replenish the toner in the toner cartridge installed in the developing device to maintain the toner density within a predetermined range. Equipped with a toner density control device.

Then, when the toner in the toner cartridge is consumed and the toner is about to become empty, the toner sensor is not replenished, so the detection signal of the toner sensor rises rapidly as shown in Figure 4, and the preset empty display is displayed. It exceeds the output. Then, when the output of the toner sensor becomes an empty display output, the control device drives the display section drive circuit, displays the empty state on the display section, and prompts the operator to replace the toner cartridge.

(Problem to be Solved by the Invention) By the way, just before the toner in the toner cartridge is consumed and becomes empty, the amount of toner falling becomes sparse, which tends to cause variations in the amount of toner replenishment in the front and rear directions of the developing device. , there is a problem that it induces the following drawbacks.

■Since only one toner sensor is provided in the front and back direction of the developing device, the amount of replenishment in the sensor section is likely to be larger than the amount of replenishment in the non-sensor section, and when such a situation occurs, the toner concentration is incorrectly detected. However, the image density in the non-sensor area decreases significantly.

(2) Conversely, if a situation occurs in which the amount of replenishment in the non-sensor portion is greater than that in the sensor portion, fogging will occur in the portion corresponding to the non-sensor portion.

Although the above problem can be solved by lowering the empty display output, there is a new problem in that it becomes difficult to accurately detect the empty state due to hunting etc., and there is a risk of false empty detection.

The present invention has been made to solve these problems, and it is an object of the present invention to provide a toner density control device that can quickly and reliably detect and display toner empty, and can also improve image quality.

(Means for Solving Problem 111) The developing device of the present invention detects the toner concentration in a two-component developer formed by mixing toner and carrier with a toner sensor, and performs development based on the detection result of the toner sensor. In a toner concentration control device that replenishes toner in a toner cartridge into the device, a calculation means reads a detection signal of the toner sensor at predetermined time intervals and calculates a change value of the toner sensor output within the predetermined time; determining means for determining that the toner in the toner cartridge is empty when a state in which the change value of the sensor output is equal to or greater than a predetermined value continues for a preset number of times; and receiving the determination result of the determining means; and display means for displaying the empty state of the toner cartridge, thereby achieving the above object.

(Function) According to the above detection method, toner consumption trends can be grasped in detail, so toner empty can be quickly and reliably detected.
Can be displayed.

(Example) The present invention will be explained in detail below.

FIG. 1 shows an embodiment of the present invention, in which a developer 7 containing a mixture of toner and carrier is stored in a container-shaped housing 2 of a developing device, and the developer 7 is rotatably driven. It is conveyed by the spiral 20 to the position of the stirring rotor 21 and stirred by the stirring rotor 21. Stirred developer 7
is attracted to the developing sleeve 22 which has a developing magnet roller fixedly arranged concentrically therein, and the developing sleeve 2
2 in the direction of arrow A, the developing sleeve 22 is conveyed in the same direction.

A doctor blade 25 is arranged in the rotation range of the developing sleeve 22 to make the layer thickness of the developer 7 uniform.The developer 7 that has passed through the doctor blade 25 is conveyed to the left end opening of the housing 2 and is Toner is supplied to the electrostatic latent image forming portion of the photosensitive drum 1 through the opening, and a developing process is performed.

On the other hand, the excess developer 7 removed from the developing sleeve 22 by the doctor blade 25 is transferred to the developing spiral 20 through a partition plate 23 disposed above the stirring rotor 21.
will be recovered at the location.

As the development process described above progresses, the toner in the housing 2 is consumed and the toner concentration in the developer 7 decreases. Toner 9 for replenishment commensurate with the toner consumption is supplied into the toner 2 .

Replenishment of toner 9, that is, control of toner concentration, is performed based on the detection output of toner sensor 24 disposed near doctor blade 25. The toner sensor 24 is a magnetic sensor composed of a coil and an oscillator, and the detection output of the toner sensor 24 is given to the CPU10. Then, the CPU10 determines whether or not toner replenishment is necessary based on the comparison result between the output of the toner sensor 24 and a preset reference voltage signal, and if it is determined that toner replenishment is necessary, the toner replenishment mechanism disposed at the upper part of the housing 2 Drive 3. As a result, the toner 9 in the toner cartridge 8, which is removably assembled to the upper end of the housing 2, is transferred to the housing 2.
A predetermined amount of toner 9 falls into the toner 9, and the toner 9 is replenished.

When the toner consumption progresses and the CPU 10 determines that the toner 9 in the toner cartridge 8 is empty as described later, it drives the display drive circuit 11 to display a display on the operation panel of the copying machine, for example. Part 12
toner empty is displayed.

Next, the principle of toner empty detection in this embodiment will be explained with reference to FIG. In the figure, T indicates the time until all of the toner 9 in the toner cartridge 8 is consumed, for example, during actual copying operation (exposure scanning operation).
This is the value obtained by integrating the total time during which the process is performed, and is hereinafter referred to as the integrated time T. Further, t indicates the time obtained by dividing the cumulative time T into N (however, in the drawing, it is divided into five for convenience of drawing). Also, the vertical axis is the detection output V of the toner sensor 24.
, and Vl, v2, v3, and v4 indicate the change values of the detection output ■ within time t. .

That is, in this embodiment, the CPU 10 reads the detection output ■ of the toner sensor 24 at every time interval, and then changes values v1, ■2, ■3, etc. of the detection output V in the time interval t.
. . . Vn is calculated, and the toner empty state of the toner cartridge 8 is detected based on the changed value.

Details of the detection mode are shown in the flowchart of FIG. That is, in step s1, the CPU 10 reads the detection output V of the toner sensor 24 at the beginning of the integrated time T and the detection output V after the time interval, and calculates the change value Vm (=V1) of the detection output V within the first time interval. ) to calculate (
S2). Incidentally, in FIG. 2, vi=o. However, m
=1.2,...n.

By repeating the above process, change values v1 and v2 for L (L<N) periods out of the total period divided into N in step S3 are obtained.
...After confirming that the calculation of Vl has been completed, in step S4, the change values v1, v2... When it is confirmed that the empty state has been reached, the display section drive circuit 11 is driven to display the empty state on the display section 12 (S5).

On the other hand, in step S4, if the change value is equal to or greater than the predetermined value, L
If the rotation is not continuous, the empty display is not performed, the first change value data in the relevant period is canceled in step S6, and the process returns to step Sl, where the same judgment as above is made regarding the data for the next L period. Execute processing.

In this way, the change value of the detection output (■) is calculated at every time interval, and the rising slope of the change value is monitored to determine whether the toner cartridge 8
According to the detection mode that determines whether the toner cartridge 8 is empty, the consumption trend of the toner 9 in the toner cartridge 8 can be grasped in detail. Therefore, toner empty can be detected quickly and reliably.
Can be displayed.

Therefore, as shown in FIG. 2, toner empty can be detected and displayed earlier than the empty detection point in the conventional example.

This means that it is possible to eliminate the adverse effect on image quality due to variations in the amount of toner replenishment in the front-rear direction of the developing device immediately before the toner becomes empty. Further, erroneous detection due to sudden toner sensor output does not occur.

Note that the values of N and L and the predetermined value corresponding to the upward slope value may be determined according to experimental results, etc., but the larger N is, the more accurate detection becomes possible.

In the above embodiment, the present invention is applied to a copying machine, but the present invention can be similarly applied to other image forming apparatuses such as printers.

(Effects of the Invention) According to the present invention, toner consumption trends can be grasped in detail, so toner empty can be quickly and reliably detected and displayed. Therefore, an adverse effect on image quality immediately before toner empty can be eliminated, and image quality can be improved. Moreover, false detection does not occur.

Figure 1 is a drawing showing an embodiment of the toner density control device of the present invention, Figure 2 is a graph showing the principle of toner empty detection, and Figure 3 is a graph showing the detection and display of toner empty.
It is a flowchart which shows the control procedure of PU.

FIG. 4 is a graph showing a conventional toner empty detection method.

7...Developer, 8...Toner cartridge, 9...
・Toner, 10...CPU, 12...Display section, 24
...Toner sensor.

that's all

Claims (1)

[Claims] 1. The toner concentration in a two-component developer formed by mixing toner and carrier is detected by a toner sensor, and the toner in the toner cartridge is transferred to a developing device based on the detection result of the toner sensor. The toner concentration control device for replenishing reads the detection signal of the toner sensor at predetermined time intervals,
a calculating means for calculating a change value of the toner sensor output within the predetermined time; and a calculating means for calculating a change value of the toner sensor output within the predetermined time; A toner density control device comprising: a determining means for determining that the toner cartridge is empty; and a display means for receiving the determination result of the determining means and displaying the empty state of the toner cartridge.