JPH02197881A - Developer detection device - Google Patents

Abstract

PURPOSE:To detect a developer quantity as an analog quantity by detecting electrostatic capacity between a rotating stirring device which is used as a first electrode and a fixed electrode. CONSTITUTION:The stirring device 2 consists of a conductor member 21 whose both ends are supported by bearing parts 20 and 20 and which is shaped in a crank state and used as the first electrode and a second stirring member 25 which has a conveyance plate 26 for strengthening the stirring force and conveying force of developer. Besides, the fixed electrode 22 which is used as a second electrode is provided on the part of the inner wall of a developing container which is shaped in a cylindrical state. By detecting the quantity of the developer with the aid of the first electrode which is made as a part of the rotating stirring device and the second electrode which is fixed to the position concentric with the rotation circle of the second electrode in such a way, the quantity of the developer from the state that a large quantity of the developer exists to the state that little developer is left is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developer remaining amount detection device for an image forming apparatus that visualizes an electrostatic latent image using a developer.

[Prior Art] Conventionally, as a means for detecting the amount of developer remaining in a developing device, an ultrasonic vibration element such as a piezo element, an inductance change detection element using a coil, etc. are used, and it is possible to detect the amount of developer remaining depending on the presence or absence of developer. There was one that took advantage of the fact that those signals changed. Furthermore, in recent years, a method of detecting the amount of developer by detecting the capacitance between electrodes has been put into practical use because of its high detection accuracy and low cost. The method using this electrode will be outlined below.

FIG. 7 is a schematic diagram showing a developer amount detection means using the above electrode. Power supply 63 applied to developing sleeve 61
A conductive wire member 6 as a toner amount detection means stretched parallel to the developing sleeve 61 by an AC bias from
2, a current flows in accordance with the impedance between the developing sleeve 61 and the conducting wire member 62, and the current is passed through the rectifier circuit 64.
The voltage is rectified and converted into a DC voltage 65, and a comparator 66 generates an output that is compared with a reference voltage 57.

Between the developing three-flow 1 and the conductor member 62, there is a difference in dielectric constant and a difference in resistance between the toner (developer) and air, so the impedance changes depending on the amount of toner in the developing device. It detects toner acid. In the case of the above example, the developing sleeve 61 and the conducting wire member 62 serve as the electrodes.

Conventional developer amount means using piezo elements etc. could only detect a single point in the developing device, but the method using the electrodes described above uses a conducting wire member stretched parallel to the developing sleeve. This means that detection can be performed throughout the entire axial direction, thus improving the accuracy.

In addition, in recent years, as a means to achieve good operability and maintenance-free operation, process cartridge type image forming apparatuses have been widely used, which integrate process units around the WI image carrier, such as a developer and a cleaner, and make them disposable. It is widespread.

In this type of image forming apparatus, especially in the above-mentioned developer detection method, only the electrodes are provided in the developing unit and the detection circuit is provided in the main body, so the cost of the cartridge does not increase. Therefore, running costs can be greatly reduced.

[Problem to be solved by the invention] However, in any case, the conventional developer amount detection means described above can only detect the remaining amount at a certain fixed position, that is, at a fixed position where the detection means is arranged. Can not.

Therefore, the above-mentioned detection means must be placed at a position where the developer is about to run out, and therefore, it is necessary to display an indication that there is no developer at such a time and prompt the operator to replenish the developer or replace the cartridge. Ta.

As a result, in the above-mentioned method, the operator is only able to tell when the amount of developer remaining is about to run out, resulting in the following inconvenience.

(2) Even if you suddenly realize that you have run out of developer, you will not be able to copy or print out until you order the developer or process cartridge because there is no spare developer to replenish or a process cartridge to replace.

■When used as an output for a computer such as a laser beam printer, or when used for facsimile, there is often no one near the printer to replenish the developer or replace the cartridge. If it is gone, you will not be able to tell even if a white spot occurs, and the information will disappear.

The present invention solves the above-mentioned particular problems and, despite its simple configuration, constantly emits a signal corresponding to the remaining amount of developer and predicts when to replenish the developer or replace the cartridge. The object of the present invention is to provide a developer detection device.

[Means for Solving the Problems] According to the present invention, the above object is to form a latent image on a latent image carrier by an electrostatic latent image forming process means disposed around the latent image carrier, A developer detecting device for an image forming apparatus in which a latent image is made to adhere to a latent image by a developing means and is visualized, the developer having at least one rotating developer stirring device in the developing device, the stirring device is attached with a first electrode that rotates together with the stirring device, and a second electrode that is fixed is attached to the other part, an applied power source is connected to the second electrode, and the first and second electrodes are connected to the second electrode. This is achieved by having a circuit that compares the value of an electrical signal based on the capacitance between the capacitance and a set reference value, and detecting the remaining amount of developer by the comparison.

[Function] According to the above-described particular aspect of the present invention, the capacitance between the first and second electrodes changes in accordance with the amount of developer per revolution of the first electrode, and this can be detected. The amount of developer is detected as an analog amount from when the amount of developer is large to when it is about to run out, and the information is transmitted to the display or external device.

[Example] Hereinafter, the present invention will be described in detail based on FIGS. 1 to 6 of the accompanying drawings.

FIG. 1 is a simple configuration diagram showing the first embodiment of the present invention, and FIG.
The figure is a sectional view thereof.

In FIG. 1, 1 is a developing sleeve, and 2 is a stirring device.

The stirring device 2 includes a crank-shaped conducting wire member 21 as a first electrode whose both ends are supported by bearing portions 20 and 20, and a conductive wire member 21 provided on the opposite side with respect to the rotation center (bearing portion 20) of the conducting wire member 21. Ta. Conveying plate 2 for stirring the developer and strengthening the conveying force
The conductive wire member 21 and the second stirring member 25 are mechanically coupled via insulating members 28 and 29, and electrically separated. The material of the conveying plate 26 is required to have a certain degree of stiffness since it is in close contact with the inner wall of the developer container so that no developer remains on the inner wall, and for example, PET, urethane rubber, etc. are selected.

The agitation device 2 is rotated in the direction of the arrow in FIG. 2 by a drive means (not shown), and conveys the developer in the direction of the development screen 1.

Further, a fixed electrode 22 as a second electrode is provided on a cylindrical portion of the inner wall of the developer container. The fixed electrode 22 is made of a conductor.

The fixed electrode 22 is arranged on a circle concentric with the circle during the rotational operation of the first electrode 21, and therefore the period during which the first electrode 21 and the fixed electrode 22 are facing each other, that is, as shown in FIG. When the electrode 21 is located between A-8, the distance between the first electrode 21 and the fixed electrode 22 as the second electrode is always constant. Appropriately, the spacing layer has a weight of about 5 to 20 layers, particularly about 1 ON- layer.

The fixed electrode 22 has a power source 4 for the developing screen 1.
3 voltage is applied, and the first electrode 21 is connected to the rectifier circuit 41. The rectifier circuit 41 is a CPU 42
The output of the rectifier circuit is A/D converted and then given an instruction.

The apparatus of this embodiment having such a configuration first has an image type 1]
t. When the operation starts, the developing sleeve 1 and the stirring device 2 rotate in the direction of the arrow (see FIG. 2). Next, an AC bias is applied to the developing sleeve 1 from the power source 43, and at the same time, the same bias is applied to the fixed electrode 22. The first electrode 21 forming a part of the stirring device 2 is connected to the fixed electrode 2.
2 (between A and 8), a current flows through the first electrode 21 according to the impedance between the fixed electrode 22 and the first electrode 21, and the current flows through the rectifier circuit. 4
1 and taken into the CPU 42 as a DC voltage.

The CPU performs A/D conversion of the voltage and monitors it.

At this time, the developer 4 is contained in the developing device as shown in FIG. 2, and when the first electrode 21 is located between A and C and when it is located between C and 8, In other words, there is a difference in the relative permittivity and resistance between the air and the developer between the first electrode 2I and the fixed electrode 22 when there is no developer and when there is a developer, so there is a difference in the detected voltage. During one rotation of the stirring rod 2, a voltage that fluctuates as shown in FIG. 3 is generated.

Furthermore, when the first electrode 21 is not at a position facing the fixed electrode 22, that is, when it is located between B and A, the distance from the fixed electrode 22 is too large, so that almost no current flows to the electrode 21. does not flow, and the detected voltage is approximately OV.

Therefore, during one rotation of the stirring device 2, a voltage as shown in FIG. 3 is generated. Here, by determining the first reference voltage and the second reference voltage as shown in FIG. It is possible to measure the amount of time the drug is present. At this time, since the rotational speed of the stirring device 2 is substantially constant, the remaining amount of developer can be detected from the ratio of a and b.

Also, when the stirring device 2 rotates, the conveying plate 25
As the fixed electrode 22 is cleaned, the amount of developer is not erroneously measured due to the developer sticking to the fixed electrode 22, and the amount of developer can be accurately detected.

In addition, there is not enough time for the stirring device to make one rotation, but for two rotations,
By taking the average of three revolutions, the detected amount of developer becomes more accurate.

As described above, by detecting the amount of developer using the first electrode that is part of the rotating stirring device and the second electrode that is fixed at a position concentric with the rotation circle of the second electrode. It is possible to constantly detect the amount of developer from when there is a large amount of developer to when it is running low, and even in the case of cartridge-type copiers and printers, there is no need to use piezo elements, etc., and the cost of cartridges is almost negligible. Since there is no increase in fuel consumption, it has become possible to reduce running costs.

In this embodiment, the remaining amount of developer is detected by the ratio of the time with developer and the time without developer, but as another method, it can also be detected by the integral value of the output level of the rotation of the stirring device. According to this method, 1. For example, when the developer is present unevenly in the axial direction of the developing sleeve (for example, immediately after the process cartridge is placed upright and installed in the main body without shaking it), the electrode is placed in the axial direction of the developing sleeve. Even if half of the developer is in the developer and the other half is in the air, and it is difficult to judge whether the developer is present or not, if it is an integral value for -rotation, it will hardly change. The remaining amount can be detected stably.

FIG. 4 is a sectional view showing a second embodiment of the present invention.

The developing device shown in FIG. 4 has a space that can accommodate approximately twice the amount of developer as the developing device shown in the first embodiment. Recently, it has become necessary to increase the number of prints, especially in cartridges, and it has become necessary to increase the amount of image forming agent, so a structure as shown in the figure has been used.

In FIG. 3, 1 is a developing sleeve, and 2 is a first stirring device 53, a second stirring device. The first stirring device 2 and the second stirring device 3 have the same configuration as the stirring device of the first embodiment described above, and each has an electrode 2t;:11. Conveying plate 2 [
It has a second stirring part 25.35 equipped with a 36 and rotates in the direction of the arrow. Further, a fixed electrode 5 is arranged on the inner wall of the developer container so as to face the electrode 21.31. In this embodiment with such a configuration, the electrodes 21 and 3
The amount of developer can be detected by adding the voltages detected from 1 to 1 and integrating the voltages over -rotation (see FIG. 5).

Still another method is to first detect the amount of developer only by the output voltage of the electrode 21, and when it is determined that there is no developer (when the developer runs out to the level D in Figure 4). It is also possible to stop monitoring the electrode 21 and detect the amount of developer from the output of the electrode 31 (see FIG. 6).

The above method increases the capacity of the developing device, and even when a plurality of stirring devices must be provided, continuous detection is possible from when the amount of developer is large to when it is small.

[Effects of the Invention] According to the second aspect of the present invention, by detecting the capacitance between the rotating stirring device as the first electrode and the fixed electrode, it is possible to The amount of developer can be detected as an analog amount from a large amount to just before it runs out, allowing the operator to always know the process until the developer runs out.
This can be addressed in advance. Therefore, it is possible to prevent problems such as suddenly running out of developer and not being able to print due to lack of spare developer, or data sent by facsimile at night disappearing.

Moreover, even in the case of the cartridge method, the cost of the cartridge hardly increases, that is, the running cost does not increase either.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of the first embodiment of the device of the present invention, Fig. 2 is a sectional view of the device of Fig. 1, Fig. 3 is a diagram showing the output of the device of Fig. 1, and Fig. 4 is a diagram of the second embodiment. A sectional view of the example device, FIG. 5 is a circuit diagram for calculation in the second example device, FIG. 6 is another circuit diagram for calculation in the second example device, and FIG. 7 is an outline of the conventional device. FIG. 2.3 - Stirring device (stirring rod) 21, :11.
...First electrode 26.36...Second electrode 3...Developer 43... Power supply patent applicant Canon Co., Ltd. Figure 5 Figure 6

Claims (1)

[Scope of Claims] A latent image is formed on a latent image carrier by an electrostatic latent image forming process means disposed around the latent image carrier, and a developer is applied to this latent image by a developing means to make it visible. A developer detection device for an image forming apparatus that performs imaging includes at least one rotating developer stirring device in a developing device, and the stirring device includes a first electrode that rotates together with the stirring device. A second electrode is attached to the other part and fixed to the other part, an applied power source is connected to the second electrode, and the value of the electric signal is set based on the capacitance between the first and second electrodes. What is claimed is: 1. A developer detection device comprising: a circuit for comparing with a reference value determined by the developer; and detecting the remaining amount of developer by the comparison.