JPS6397984A - Waste toner detector - Google Patents

Abstract

PURPOSE:To accurately detect the amount of toner even in a movable waste toner container by applying an AC voltage between electrodes arranged in the container and detecting the amount of toner from the variation of a current. CONSTITUTION:Toner scraped off the surface of an image carrier 1 by a cleaning blade 2a is guided a tube 3 from inside a cleaning device 2 into the container which is a hollow in the image carrier 1. The electrodes 5 and 7 are arranged in the container at proper eccentric positions off the center of its rotation; and the electrode 5 is connected to a conductive ring 8 connected to an AC high voltage power source 4 and the electrode 7 is connected to a conductive ring 9 connected to a detecting circuit 6. The electrodes 5 and 7 form a capacitor and the current flowing between the electrodes 5 and 7 changes its behavior in every turn of the image carrier 1. Consequently, the detecting circuit 1 detects the state of the current to know the amount of toner in the image carrier 1.

Description

Detailed Description of the Invention (1) Purpose of the Invention (Industrial Applicability!?) This invention relates to a cleaning device used in an image forming apparatus that utilizes an electrostatic recording process, such as an electrostatic copier or printer. The present invention relates to the waste toner detection device.

(Prior art and issues to be solved) A transferable toner image formed on the surface of a moving image carrier,
In well-known image forming apparatuses that repeat the process of transferring to a sheet-like transfer material, mainly paper, each time, the residual toner that does not contribute to the transfer and remains on the surface of the image carrier is sufficiently removed. It is necessary to remove it beforehand to prevent deterioration of image quality in the next process and thereafter.

For this reason, this type of image forming apparatus is usually configured to be equipped with an appropriate cleaning means such as a cleaning blade to remove residual toner.
Since the capacity of the cleaning device itself equipped with the cleaning means is not very large, conventional methods have been constructed in such a way that the toner stored in the device is guided into a separate waste toner container. It is widely used.

The amount of toner accumulated in the toner container is determined by arranging a light emitting element and a light receiving element so that there is an optical path in the interior space of the container, and generating a full signal when the optical path is blocked by M accumulated toner. There are known methods that detect and process waste toner by estimating whether the container is full based on the average amount of waste toner that comes out for each transfer.

If the image forming apparatus is relatively large and there is plenty of space within the apparatus, this method will not pose any particular problem, but in recent years, image forming apparatuses have become smaller and more compact. In the case of a small-sized image forming device, several parts such as a charger, a developing device, and a cleaning device, which should be placed in and around the body, are integrated into a cartridge, and this part is made disposable. Since the space within the apparatus is small, it has been proposed to guide and store waste toner in the hollow space of an image carrier, which is generally formed in the shape of a hollow rotating cylinder, without providing a separate waste toner container.

Generally, in this type of toner container, if toner is stored 11 times in a row until the container is full, the function of the cleaning device will be adversely affected, resulting in poor cleaning and
Based on this, it is necessary to detect the amount of toner in the container and discard the toner or replace the container when it is full, as this may lead to deterioration in image quality.

In particular, in the case of image forming apparatuses that use a cartridge method as described above, there are approximately certain times when the image bearing member has a lifespan, when the toner in the developing device runs out, and when the waste toner container (image bearing member) becomes full. It would be advantageous to have a match, but for this purpose it is extremely important to accurately detect the amount of waste toner externally.

However, when the image carrier is used as a waste toner container, since this body rotates, the toner accumulated inside does not maintain a stable state and tends to move around as the image carrier rotates. , it dances like dust in the internal space, so methods that use blocking of the optical path as mentioned above are likely to cause false detection, and methods that use the amount of waste toner generated as a standard are not very accurate. Quantification is impossible.

This cannot be said to be an effective means due to the relationship between the usable period and other components in the cartridge.

The present invention has been made in order to cope with such a situation, and it is an object of the present invention to provide a waste toner detection device that can accurately detect the amount of toner even in a movable waste toner container.

(2) Structure of the Invention (Technical Means for Solving the Problems and Their Effects) In order to achieve the above objects, the present invention provides the following features: A constant alternating current voltage is applied to the toner, and the amount of toner is detected based on a change in the voltage due to a change in the amount of toner.

With this configuration, the amount of toner can always be detected accurately, and the cartridge can be used effectively, especially in an image forming apparatus that uses a cartridge method.

(Description of an Embodiment) FIG. 1 is a partially cutaway schematic diagram showing a main part of an embodiment in which the present invention is applied to a copying machine having a rotating cylindrical image carrier. A cleaning device 2 is arranged close to the cleaning device 2 in parallel, and a cleaning blade 2a attached to the cleaning device 2a presses against the image carrier to remove waste toner adhering to the image carrier.
.

As is well known, around the image carrier, -
It goes without saying that members required for image formation, such as a charger, a developer, and a transfer charger, are provided, but since they are not directly related to the present invention, they are all omitted.

The toner scraped off from the surface of the image carrier by the cleaning blade accumulates in a storage section in the cleaning device, and is then transferred to a container, which is a cavity inside the image carrier, by a conveying screw (not shown) disposed in the tube 3. be guided.

A pair of electrodes 5.7 are disposed inside the container at appropriate eccentric positions away from the center of rotation, and the electrodes 5 are connected to the AC high voltage power source 4 via a conductive wire surrounded by an insulating tube 5a. The electrode 7 is connected to the detection circuit 6 via a conductive wire surrounded by an insulating tube 7a, and is connected to a conductive ring 8 provided on the outer periphery of the image carrier, so that the conductive ring 8 is connected to a conductive ring 8 provided on the outer circumference of the image carrier. These are connected to the ring 9, respectively.

Here, if the distance between the electrodes 5.7 is d and the area is S, then both electrodes form a capacitor with a capacitance of C=εS/d (1).

Air (e=1) or toner (ε=2-3) between the electrodes
Therefore, by applying a constant AC voltage between the electrodes, the change in ε in equation (1) can be determined by the current flowing between the electrodes.

Here, if an AC voltage of E(ω) = E (2πf) is applied between the electrodes, the current becomes.

The dielectric constant of the air inside the photoreceptor is 61, and that of the waste toner is (2).
Then, when there is no waste toner, a current flows, and when there is toner between the electrodes, a current flows.

Here, it is assumed that the toner inside the photoconductor is generally located at the bottom of the photoconductor due to gravity.

Therefore, as shown in FIG. 1, when the electrodes are at eccentric positions, the behavior of the current flowing between the electrodes for each rotation of the photoreceptor is as follows: 1) Only It(ω) flows.

Ru.

’) 1’l (U)) only flows.

These cases respectively indicate a state in which there is almost no toner in the photoreceptor, a state in which a certain amount of toner exists, and a state in which a predetermined amount of toner has accumulated.

FIG. 2 shows only the positive portion of the current corresponding to each of the above states.

Therefore, by detecting the state of the current with the detection circuit 6, it is possible to know the amount of toner in the photoreceptor, which is the waste toner container.

The above device is equipped with an AC power source for applying voltage between the electrodes, but it is of course possible to use the power source used for the transfer material separation means, developing bias, etc. It is.

3A and 3B show one electrode arranged near the photoreceptor rotation axis, and FIG. 4 shows both electrodes arranged near the periphery of one side wall of the photoreceptor. By arranging at least one of the electrodes at an eccentric position near the peripheral wall of the photoreceptor, the amount of toner can be detected in the same way as in the above-mentioned ones.

(3) Effects of the Invention Since the present invention has the configuration described above, even when a moving member such as an image bearing member such as a photoreceptor is used as a waste toner container, the amount of toner can be accurately determined. This allows the cleaning device in the image forming apparatus to always function effectively.Especially in the case of a cartridge-type image forming apparatus such as the one described above, it is possible to detect the toner consumption of the developing device and the life of the photoreceptor. This has the effect of making it easier to maintain consistency with other systems.

[Brief explanation of the drawing]

FIG. 1 is a side view of main parts showing an embodiment in which the present invention is applied to a copying machine that uses a photoreceptor as a toner container. FIG. 2 is a graph showing the relationship between toner amount and current. FIG. 4 is a sectional view of a main part illustrating the arrangement of electrodes. 1.11 photoreceptor, 2..cleaning device, 3..
・Transport tube, 4...AC power supply, 5°7...electrode, 6...detection circuit, 8.9・os conductive ring, Fig. 2 t (between 4) Drum 1FEI period (1) (illustration (3)

Claims (2)

[Claims] (1) In an image forming apparatus in which waste toner removed from an image carrier by a cleaning device is stored in the image carrier as a toner container, a toner sensor is arranged to detect the presence of toner in the image carrier. Waste toner detection device. (2) The waste toner detection device according to claim 1, wherein the toner sensor includes two electrodes, and an AC voltage with a constant effective value is applied between the two electrodes.