JPS63210871A - Device for detecting residual amount of developer - Google Patents

Abstract

PURPOSE:To permit always exact detection without generating erroneous detection even if a change in the characteristics of a developer arises by providing a function to set the set reference value of a comparator according to a fluctuation of a developing bias or environmental change. CONSTITUTION:The novel reference voltage generating means to change the set reference voltage of the comparator 9 according to the fluctuation of the output voltage of an AC bias power supply 4 and the environmental change in the characteristics of the developer T is provided. This reference voltage generating means is constituted of a hermetic chamber 13, the developer T housed therein, a 1st electrode 14, a 2nd electrode 15, and a signal processing means. The detected signal voltage VDC generated from a current-voltage conversion circuit 8a and the reference voltage VS generated from the reference voltage generating means are compared in the comparator 9, by which the reference voltage can be changed automatically according to the change in the characteristics of the developer T by a change in temp. and humidity. The danger of generating the erroneous detection is, therefore, entirely eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Uses of the Invention) The present invention relates to a developer remaining amount detection device for detecting the developer remaining amount state of a developing device used in an image forming apparatus or the like.

[Background of the invention]

A developing device installed in an image forming apparatus such as an electrophotographic device is often a dry type developing device that uses a powder developer. The developing device generally includes a box-shaped developer container that contains developer (toner) to be supplied to an electrostatic latent image carrier such as a photosensitive drum, and a box-shaped developer container that supplies the developer from within the developer container to the electrostatic latent image carrier. It has a rotary developer carrier which is conveyed little by little toward the electrolatent image carrier. During operation of the image forming apparatus, the developer in the developer container is carried out by the developer carrier, so the amount of developer in the developer container decreases. When the remaining amount of developer in the developer container falls below a certain value, the amount of developer carried out by the developer carrier also decreases, resulting in a situation where the quality of the image deteriorates. Therefore, in order to prevent such a situation from occurring, the amount of developer remaining in the developer container must be constantly monitored to ensure that the amount of developer remaining in the developer container does not fall below a predetermined level. When the level of the developer in the developer container falls below a certain value, the developer must be replenished into the developer container immediately.

2. Description of the Related Art Conventionally, a device having a configuration shown in FIG. 5, for example, is known as a device for detecting the amount of developer remaining in a developing device.

In FIG. 5, 5 is a photosensitive drum of an image forming apparatus, 1 is a developer container containing a developer T, and 2 is a developer carrier disposed at a side opening of the developer container 1, that is, a developer. A sleeve 6 is a conductive detector disposed in parallel with the developing sleeve 2 within the developer container 1; 3 is a conductive detector provided at a side opening of the developer container 1 to detect the developed image attached on the developing sleeve 2; A blade 4 adjusts the thickness of the developer layer; 4 is an AC bias power source that applies a developing bias to the developing sleeve 2; a rectifier circuit that rectifies the current induced in the detector 6, 8a a current-voltage conversion circuit that converts the current signal generated by the rectifier circuit 7a into a voltage, 12 a reference voltage generation circuit that generates a reference voltage signal, 9 10 is a comparator that compares the measured voltage (detected voltage) generated from the current-voltage conversion circuit 8a with a reference voltage and produces an output when the two voltages match;
is a display circuit that controls the display 11 according to the output state of the comparator 9. The developer remaining amount detection device includes a detector 6 and various circuits 7a to 7a that operate according to the output signals of the detector 6.
10 and 12 and a display 11.

In the developer remaining amount detection device as described above, the output of the detector 6 is the amount of developer between the developing sleeve 2 and the detector 6,
It varies depending on the magnitude of the developing bias applied to the developing sleeve 2 and changes in developer characteristics due to environmental changes such as temperature and humidity, but is caused by the amount of developer between the developing sleeve and the detector. The only output required is the measurement output, and the outputs due to the other two causes are unnecessary noise. Therefore, when an unnecessary output occurs as described above in the output of the detector 6, the final detection result is automatically corrected so that an erroneous detection result does not occur due to the unnecessary output. However, in the conventional developer remaining amount detection device shown in FIG. Since the value was set to a constant value regardless of the relationship, erroneous detection often occurred when an apparent change in the output of the detector 6 occurred due to a change in the developing bias or a change in developer characteristics.

Note that the AC bias power supply 4 used with conventional developing devices generally has an output fluctuation tolerance range of ±10%, and therefore causes a maximum output fluctuation of ±10%. An apparent output is produced in the detector 6, and as a result, in the conventional developer remaining amount detection device, erroneous detection is likely to occur due to output fluctuations of the AC via and the smear source 4.

[Purpose of the invention]

An object of the present invention is to provide an improved developer remaining amount detection device that does not cause the above-mentioned false detection.

[Summary of the Invention] The improved developer remaining amount detection device according to the present invention changes the set reference voltage in the comparator 9 to the AC bias power supply 4.
The present invention is characterized by having a novel reference voltage generating means that changes in response to fluctuations in the output voltage of the developer and changes in characteristics of the developer due to the environment. The reference voltage generating means includes a sealed chamber that is isolated from the inside of the developer container and filled with developer to a predetermined level, and a first voltage generator that is embedded in the developer in the sealed chamber and connected to an AC bias power source. an electrode, a second electrode disposed opposite to the first electrode in the space in the sealed chamber, and an output of the 2'E pole connected between the second electrode and the reference voltage input terminal of the comparator. According to the reference voltage generating means, the reference voltage set in the comparator 9 is adjusted according to output fluctuations of the AC bias power supply 4 or changes in temperature, humidity, etc. Since it can be changed to automatic detection according to changes in the characteristics of the developer, the risk of false detection can be completely eliminated.

[Embodiments of the invention]

The structure, functions, etc. of the improved developer remaining amount detection device according to the present invention will be explained below with reference to FIGS. 1 to 4.

FIG. 1 is a schematic diagram of an embodiment of the improved developer remaining amount detection device according to the present invention. In FIG. 1, the same parts as in the conventional device shown in FIG. 5 are indicated by the same reference numerals as in FIG. 5, and a description of these same parts will be omitted.

The embodiment of the present invention shown in FIG. 1 is characterized in that a novel reference voltage generating means for setting the reference voltage V in the comparator 9 is provided in conjunction with the AC bias power supply 4.

In the developer remaining amount detection device of the present invention, the developer container 1
A sealed chamber 13 isolated from the interior of the developer container 1 is provided in the developer container 1, and a first electrode 14 is provided embedded in the developer T contained in the sealed chamber 13 to a predetermined level.
A second electrode 15 is provided in the space inside the sealed chamber 13 opposite to the first electrode 14, and between the second electrode 15 and the input terminal for setting the reference voltage of the comparator 9. , a rectifier circuit 7 that rectifies the current generated in the second electrode 15.
A second signal processing means is connected, which includes a current-voltage conversion circuit 8b that converts the rectified direct current into a voltage.

That is, the sealed chamber 13, the developer T contained in the sealed chamber 13, the first electrode 14, the second electrode 15, and the second signal processing means constitute a reference voltage generating means. In the comparator 9, the current-voltage conversion circuit 8
The detection signal voltage VDC generated from a is compared with the reference voltage v5 generated from the reference voltage generating means, and when VOC becomes larger than vs, an output is generated in the comparator 9, actuating the display circuit 10, and displaying it on the display 11. It is displayed that the developer in the developer container 1 is almost empty.

The amount of developer stored in the sealed chamber 13 is determined as follows.

For example, if it is assumed that when the remaining amount of developer in the developer container 1 reaches 50 g, the display 11 is to display that "the amount of toner in the developer container 1 is almost empty", the developer container 1 The amount of developer in the sealed chamber 13 is determined so that the detection signal voltage vnc manually inputted to the comparator 9 and the reference voltage VS will be the same value when the remaining amount of developer in the chamber reaches 50 g.

In FIG. 2, the voltages VDC and vs are plotted on the vertical axis, and the amount of developer remaining in the developer container 1 (g) and the amount of developer in the sealed chamber 13 are plotted on the horizontal axis. 4 shows changes in the voltages VDC and vs with respect to the amount of developer in the sealed chamber 13.

' Referring to figure M2, the reference voltage Vs matches the value of the detection signal voltage νDe at which the remaining amount of developer is 50 g when the amount of developer in the sealed chamber 13 reaches m (g). will be understood. That is, in order to cause the comparator 9 to generate an output when the remaining amount of developer in the developer container 1 reaches 50 g, it is sufficient to seal m (g) of developer in the sealed chamber 13. Become.

In FIG. 3, the horizontal axis represents the amount of developer remaining in the developer container 1.
The reference voltage v3 and the detection signal voltage VDC are plotted on the vertical axis, and the relationship between the detection signal voltage and reference voltage and fluctuations in the output voltage of the AC bias power supply 4 is shown. When the output voltage of the AC bias power supply 4 is the normal voltage VPP as shown by the solid line, the value of the detection signal voltage vIllc and the value of the reference voltage vs when the remaining amount of developer in the developer container 1 is 50 g are normal. However, if the output voltage of the AC bias power supply 4 is a voltage VPP l larger than the normal voltage VPP as shown by the dotted line, the value of the detection signal voltage VDC when the remaining amount of developer is 50 g and The value of reference voltage v5 is Vs+
(Vs+>Vso), and the value of the detection signal voltage and the value of the reference voltage also increase in accordance with the output voltage of the AC bias power supply 4. Further, when the output voltage of the AC bias power supply 4 is a value VPP2 smaller than the normal value vpp, the value of the detection signal voltage VOC and the value of the reference voltage VS are also the normal value VP.
The value VPP2 is smaller than P.

As shown in FIGS. 1 and 3, in the developer remaining amount detection device of the present invention, a voltage source 8i14 serving as a reference voltage setting means for setting a reference voltage in the comparator 9 is connected to the AC bias power source 4. Therefore, when the output voltage of the detector 6 changes due to a change in the output voltage of the AC bias power supply 4, the output voltage of the electrode 15, that is, the reference voltage of the comparator 9 also changes. Apparent fluctuations in the detection signal voltage VDc can be removed.

In FIG. 4, the vertical axis represents the detection signal voltage ν. . and the reference voltage Vs, and the horizontal axis shows the amount of developer remaining in the developer container 1, and the detection signal voltage VD is determined by environmental changes in temperature and humidity.
This shows how C changes.

The detection signal voltage VNN at room temperature is as shown in the solid line in the figure, and the value of vNN when the remaining amount of developer is 50 g matches the regular reference voltage VSO, but the detection signal voltage V) IN at high temperature and high humidity is as shown in the figure. As shown by the dotted line, the value of VHH when the remaining amount of developer is 50 g is a value v larger than the regular reference voltage VS.
It becomes sH.

In addition, the detection signal voltage VLL when the temperature is low and low humidity is as shown in the dashed line as shown in the figure, and VL when the remaining amount of developer is 50 g.
The value of L is smaller than the regular reference voltage VSO.
becomes.

However, in the device of the present invention, since the terminals 8i14 and 15 serving as reference voltage setting means for setting the reference value of the comparator 9 are provided adjacent to the developer container 1 and in the same environment as the detector 6, the reference voltage vs is also the output signal of the detector 6, that is, the detection signal voltage ■. Since it changes with C,
When the detection signal voltage VDC fluctuates due to environmental changes (i.e., temperature and humidity fluctuations), the set voltage at the comparator 9 also changes automatically, so there is a risk of false detection due to apparent output fluctuations caused by environmental changes. Therefore, accurate detection can be performed at all times.

It goes without saying that the developer remaining amount detection device of the present invention can be applied not only to detecting the state of developer remaining in the developing device, but also as a developer replenishment control device for replenishing developer to the developing device.

〔Effect of the invention〕

As explained above, the developer remaining amount detection device of the present invention has a function of automatically changing the set reference value of the comparator 9 in response to fluctuations in the developing bias and environmental changes. Even if the characteristics of the developer change due to fluctuations in the amount of fluid or changes in the environment, false detection will not occur, and the remaining amount of developer can always be accurately detected.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the remaining amount of developer detecting device according to the present invention, and FIG. Figure 3 shows the detection signal voltage VDC applied to the comparator 9.
Fig. 4 shows a state in which the detection signal voltage applied to the comparator 9 is affected by changes in the environment of the developer. 1 is a schematic diagram of a conventional developer remaining amount detection device. 1... Developer container 2... Developing sleeve (developer carrier) 3... Blade 4... AC bias power supply 5... Photosensitive drum (electrostatic latent image carrier) 6... Detection Child 7a,
7b... Rectifier circuit 8a, 8b... Current-voltage conversion circuit 9... Comparator 10... Display circuit 11...
・Display device 12...Reference voltage generation circuit 13・
... Sealed chamber 14... First electrode 15...
2nd electrode Figure 1 Figure 2 Figure 3 Vs, Voc Figure 4 M □ Remaining amount of polishing agent

Claims (1)

[Scope of Claims] A detector disposed in a developer container together with a developer carrier such as a developing sleeve connected to an AC bias power supply; a first signal processing means for rectifying a current induced in the detector according to the amount of developer present between the detector and converting it into a voltage to obtain a measurement voltage; a reference voltage and the measurement voltage; and a comparison means for comparing the remaining amount of developer, wherein a closed chamber is provided adjacent to the developer container and is isolated from the interior of the developer container and filled with developer to a predetermined level; A first electrode is provided in the sealed chamber, which is buried in the developing area in the sealed chamber and connected to the AC bias power supply, while a first electrode is provided in the space in the sealed chamber opposite to the first electrode. A second signal processing means for rectifying a minute current generated in the second electrode and converting it into a voltage in accordance with fluctuations in the output voltage of the AC bias power supply is arranged between the second electrode and the comparison means. A developer remaining amount detection device characterized by being connected between.