JPH02114281A - Developing device for electrophotographic device - Google Patents

Abstract

PURPOSE:To surely detect the remaining quantity of toner and, at the same time, to prevent a decline in the service life of a light emitting diode by providing a driving means which instantaneously makes a drive current to flow for causing the diode to emit light higher than a prescribed level in intensity and a remaining toner quantity detecting means which detects the remaining quantity of the toner based on the detecting signal of a light receiving element when the drive current is instantaneously made to flow by means of the driving means. CONSTITUTION:A light emitting diode 5 which emits light toward the inside of toner contained in a toner housing section 1, light receiving element 6 which receives the light emitted from the diode 5, and driving means 9 which instantaneously makes a drive current to flow for causing the diode 5 to emit the light higher than a prescribed level in intensity are provided. In addition, a remaining toner quantity detecting means 10 which detects the remaining quantity of the toner in the section 1 based on the detecting signal of the element 6 when the drive current is instantaneously made to flow by means of the means 9 is also provided. The strong light produced by the instantaneous large current is not completely blocked by the toner adhering to the light emitting surface of the diode 5 and light receiving surface of the element 6 and part of the light reaches the element 6. Therefore, the remaining quantity of the toner can be detected surely and a decline in the service life of the light emitting diode can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing device used in, for example, an electrophotographic non-impact printer, and particularly relates to detecting the amount of remaining toner in the developing device.

[Conventional technology]

The general operation of an electrophotographic non-impact printer is as shown below. That is, first, an image light is irradiated onto a photoreceptor (toner image bearing #) whose surface is uniformly charged to form an electrostatic latent image on the surface of the photoreceptor. Next, the charged toner contained in the cartridge (toner storage unit) of the developing device is supplied to the electrostatic latent image portion of the photoreceptor to form a toner image on the photoreceptor. This toner image is transferred onto a transfer paper by the action of corona discharge, and then fixed by heating and pressure.

As described above, the toner is contained in the cartridge of the developing device, and is discharged from the cartridge during the developing operation in the image forming process. Therefore, when the amount of toner remaining in the cartridge falls below the reference value, it is necessary to replenish toner.

There have been various types of toner remaining amount detection methods, for example, one that detects the mixing ratio of toner and magnetic carrier in the cartridge based on changes in the magnetic field, and one that detects the top surface position of the accumulated toner in the form of a blade. There are detection members that detect mechanically.

[Problem to be solved by the invention]

However, in the above configuration, there is a problem that the circuit configuration or mechanical configuration becomes complicated and the device becomes expensive.

Therefore, a configuration without a drive unit is provided with a light emitting diode that emits light into the cartridge and a phototransistor that detects the light from the light emitting diode.The remaining amount of toner is detected based on the output signal of the phototransistor. One possible method is to do so.

That is, when the light from the light emitting diode is blocked by toner and the phototransistor is off, the presence of toner is detected, and when the phototransistor is on, the absence of toner is detected.

This combination of a light emitting diode and a phototransistor has the advantage of not having a mechanical drive unit and having a simple circuit configuration.

However, even if the remaining amount of toner in the cartridge decreases below the standard value, the light emitting surface of the light emitting diode, the light receiving surface of the phototransistor, or the surface of the threshold plate provided on the optical path from the light emitting diode in the cartridge. There may be toner attached. In this case, the light from the light emitting diode may be blocked by the adhered toner, and it may be erroneously detected that the remaining amount of toner is greater than or equal to the reference value even though it is less than or equal to the reference value. Therefore, this configuration could not be a practical detection method.

Therefore, the present invention is directed to the above-mentioned improvements. It was developed to solve problems in advanced technology, and its purpose is to provide a developing device for electrophotographic devices that can reliably detect the amount of remaining toner with a simple configuration using a light emitting diode and a light receiving element. It's about doing.

[Means to solve the problem]

A developing device for an electrophotographic apparatus according to the present invention includes a toner storage section that stores toner, and a toner supply means that supplies the toner in the toner storage section onto a toner image bearing member. a light-emitting diode that emits light toward the inside of the toner in the toner storage section; a light-receiving element that receives the light emitted by the light-emitting diode; and a drive that instantaneously flows a drive current that causes the light-emitting diode to emit light with a predetermined intensity or higher. and a remaining toner amount detecting means for detecting the remaining amount of toner based on a detection signal of the light receiving element when a driving current is momentarily applied by the driving means.

[For production]

The developing device of the electrophotographic apparatus of the present invention employs a driving method in which a large current is instantaneously passed through a light emitting diode.

The strong light emitted by this large current is not completely blocked by toner adhering to the light-emitting surface of a light-emitting diode or the light-receiving surface of a phototransistor, for example.
A part of it is allowed to reach the light receiving element. Therefore, there is a low risk of false detection of a toner presence signal even though there is no toner.Also, since light emitting diodes can withstand large currents when driven momentarily, shortening of the life of light emitting diodes is prevented. can.

〔Example〕

The present invention will be explained below based on illustrated embodiments.

FIG. 1 is a schematic perspective view showing an embodiment of a developing device of an electrophotographic apparatus according to the present invention. In the figure, 1 is a cartridge (toner accommodating portion) that stores toner T, 2 is a toner supply roller that supplies toner onto a photoreceptor (toner image bearing member) not shown, 3 is a rotation shaft of the toner supply roller 2,
4 is a gear attached to the rotating shaft 3. That is, when rotational driving force is transmitted to the gear 4 from a motor (not shown), the toner supply roller 2 connected to the rotating shaft 3 rotates in the direction of the arrow in the figure, and the toner T is delivered to the opening gla of the cartridge 1.
The photosensitive material is supplied onto the photoreceptor through the photoreceptor.

In this embodiment, the following configuration is provided in order to detect whether the remaining amount of toner T contained in the cartridge 1 is below a predetermined amount. That is,
A light emitting diode 5 is provided on one side wall 1b of the cartridge, and a phototransistor 6 as a light receiving element is provided on the other side wall IC facing the side wall 1b. Light is emitted from the light emitting diode 5 toward the inside of the cartridge 1, and this light is configured to pass through the internal space of the cartridge 1 and enter the phototransistor 6. Note that 7 and 8 are threshold plates provided in the cartridge 1 to partition the toner accommodation range, and have translucent windows through which the light from the light emitting diode 5 passes.

Therefore, when toner is accumulated in the cartridge 1 and light from the light emitting diode 5 to the phototransistor 6 is blocked by the toner T, the phototransistor 6
is turned off and the presence of toner can be detected, and when toner T is not present in the optical path from the light emitting diode 5 to the phototransistor 6, the phototransistor 6 is turned on and the absence of toner can be detected.

However, in the case of the above configuration, even though the toner T is not deposited in the cartridge 1, the threshold plate 7 or 8
Toner may adhere to the surface of the window of the light emitting diode 5, and there is a risk of false detection (judgment that there is toner when there is no toner).Therefore, in this embodiment, the light emitting diode 5
Rather than turning on the lamp all the time, the lamp is controlled to turn on instantly using a large current, and repeatedly at predetermined intervals.

FIG. 2 is a circuit diagram showing an example of a circuit for implementing such lighting control, and FIG. 3 is a timing chart showing the operation of this circuit. In this figure, the same components as in FIG. 1 are given the same reference numerals.

That is, 5 is a light emitting diode, and 6 is a phototransistor. Further, 9 drives the light emitting diode 5. Drive circuit (transistor 9a and resistor 9b.

9C), and 10 is a control means for outputting a D-ON signal at a predetermined period and controlling the operation of the drive circuit 9 so that a predetermined current flows from the power source V to the light emitting diode 5.
It is a CPU. Further, μCPU10 has a function as a remaining toner amount detecting means for detecting whether the phototransistor 6 is on or off.

As shown in FIG. 3, the operation of the above circuit is such that the D-ON signal of the μCPU 10 is output at a predetermined period, turns on the transistor 9a of the drive circuit 9 at the same period, and instantaneously causes the light emitting diode 5 to have a large A current is applied to emit instantaneous intense light.

As described above, by controlling the light-emitting diode to instantaneously flow a large current at a certain period, it will not emit light even if there is toner on the surface of the threshold plate 5 or 6 when there is no toner T in the cartridge 1. The strong light emitted from the diode 5 is not completely blocked and a portion reaches the phototransistor 6. Therefore, toner T is in cartridge 1
When the toner is empty, it can be reliably detected that there is no toner, and the risk of false detection is extremely low.Furthermore, in this embodiment, μCPU10 is used to shorten the time for applying current to the light emitting diode 5, so the amount of time required to apply the current to the light emitting diode 5 is reduced. Even if current is applied, the life of the light emitting diode will not be shortened.

Note that when there is sufficient toner in the cartridge 1, the light emitted from the light emitting diode 5 is naturally blocked by the toner accumulated in the cartridge 1 and does not reach the phototransistor 6. Therefore, the phototransistor 6 It is turned off and μCPUl0 can detect the presence of toner.

Further, in the above embodiment, the cartridge 1 is provided with a threshold plate, but the present invention is not limited to this, and the cartridge 1 is provided with a light emitting diode and a phototransistor without the threshold plate. It can also be applied when

〔Effect of the invention〕

As explained above, according to the present invention, a current larger than a steady current is instantaneously applied to the light emitting diode to generate strong light, so that during the optical path between the light emitting diode and the light receiving element,
For example, even if toner adheres to the surface of the threshold plate, the remaining amount of toner can be accurately detected.

Further, since the configuration of the present invention does not have a driving section and is simple in configuration, an inexpensive device can be provided.

Furthermore, since the large current applied to the light emitting diode is instantaneous, there is no risk of shortening the life of the light emitting diode.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view showing one embodiment of a developing device of an electrophotographic apparatus according to the present invention, FIG. 2 is a circuit diagram of this embodiment, and FIG. 3 is a time chart showing the operation of this embodiment. . DESCRIPTION OF SYMBOLS 1... Cartridge (toner storage part), 2... Toner supply roller (toner supply means), 5... Light emitting diode, 6... Phototransistor (light receiving element). Patent applicant Oki Electric Industry Co., Ltd. Agent Patent attorney Former 1) Actual

Claims (1)

[Scope of Claims] A developing device for an electrophotographic apparatus, comprising: a toner storage section that stores toner; and a toner supply means that supplies the toner in the toner storage section onto a toner image carrier; a light-emitting diode that emits light toward the light-emitting diode; a light-receiving element that receives the light emitted by the light-emitting diode; a drive unit that instantaneously flows a drive current to cause the light-emitting diode to emit light with a predetermined intensity or more; and the drive unit. 1. A developing device for an electrophotographic apparatus, comprising: a remaining amount of toner detecting means for detecting a remaining amount of toner based on a detection signal of the light receiving element when a driving current is momentarily applied.