JP2003122107A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device in which antenna voltage fluctuation with respect to environmental humidity change, is restricted and accuracy in the detection of the quantity of toner is enhanced. SOLUTION: The developing device has a developing container for storing developer, and a developing sleeve 2 disposed freely rotatably in the opening of the lower part of the developing container and used for supplying the developer to an image carrier. The developing device also has an antenna 1 disposed near the developing sleeve 2 within the developing container, a remaining quantity detecting part that detects a quantity of remaining developer by detecting electrostatic capacitance between the developing sleeve and antenna, and a movable support part 30 supporting the antenna 1 so that a distance between the antenna 1 and the developing sleeve is variable. The developing device further has a moisture-sensitive member 33 for varying the distance between the antenna and the developing sleeve by reversibly expanding/contracting according to environmental moisture change.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device suitable for being mounted on various image forming apparatuses such as an electrophotographic copying machine, an electrostatic recording device, and a laser beam printer, and more particularly to a developing device housed in a developing container. The present invention also relates to a developing device having a remaining amount detecting means for detecting the remaining amount of the developer.

[0002]

2. Description of the Related Art An outline of a conventional developing device mounted on a conventional image forming apparatus is shown in FIG. The developing device 3
It is arranged around a photosensitive drum (image carrier) 8 on the surface of which an electrostatic latent image is formed by an unillustrated charging device, exposure means, and the like. Further, a cleaning device 10 for removing and collecting the toner (developer) remaining on the photosensitive drum 8 is provided on the substantially opposite side of the developing device 3.

The developing device 3 holds a developing sleeve (developer carrying member) 2 for carrying and conveying toner, a developing blade 6 for regulating the thickness of the toner layer on the developing sleeve 2 and charging the toner, and housing the toner. The developing container 4 includes a stirring member 12 that stirs and conveys toner, and an antenna 50 that detects the remaining amount of toner.

Now, the principle of detecting the remaining amount of toner in the developing container 4 by the antenna 50 will be described. For example, in the developing device 3, the electrostatic capacitance between the developing sleeve 2 and the antenna 50, which changes depending on the amount of toner in the developing container 4, is detected by an equivalent circuit as shown in FIG. In the figure, 22 is an AC power supply for applying a developing bias, 20 is the same DC power supply, 24 is an antenna 50 and the developing sleeve 2
, 18 represents a developing sleeve as an electrode, and 16 represents an antenna as an electrode. The AC power supply 22 generates a rectangular wave of 2600 Hz and 1600 Vpp, for example.

In this circuit, the capacitance of the capacitor 24 changes with the dielectric constant between the electrodes 18 and 16 which changes depending on the amount of toner between the developing sleeve 2 and the antenna 50.

As a result, the AC component of the developing bias input to the remaining amount detecting circuit 14 changes. For example, by rectifying this AC component and measuring the change in this signal, the amount of toner in the developing container 4 is measured. Can be detected.

With respect to the amount of toner thus detected,
On the side of the image forming apparatus main body, in order to prevent white spots and the like in the image due to the toner shortage, a display for notifying the user of the replacement time of the cartridge is displayed or the apparatus main body is stopped. The value of the output voltage (hereinafter also referred to as the antenna voltage) of the remaining amount detection circuit when the toner amount becomes low is recorded in the CPU, and the actual antenna voltage is recorded (set) in the CPU. If:
The above alarm operation is activated.

[0008]

However, when the humidity environment in which the developing device is installed changes, the antenna voltage changes even with the same toner amount. In particular, when the voltage for the developing bias changes due to the environmental humidity, the value of the antenna voltage also changes accordingly, which causes a problem that the alarm operation is not performed at an appropriate time.

From this background, it is an object of the present invention to provide a developing device which suppresses the variation of the antenna voltage with respect to the variation of environmental humidity and improves the accuracy of toner amount detection.

[0010]

In order to achieve the above object, the invention according to claim 1 is a developing container containing a developer, and the developing container is rotatably disposed in a lower opening of the developing container. A developer carrier for supplying the developer to the image carrier, an antenna arranged in the developing container in the vicinity of the developer carrier, and a capacitance between the developer carrier and the antenna are provided. In a developing device provided with a remaining amount detecting means for detecting the remaining amount of the developer by detecting, a movable supporting means for supporting the antenna so that a distance between the antenna and the developer carrier can be changed, and an environment. The present invention is characterized by comprising a humidity sensitive unit that reversibly expands and contracts according to a change in humidity to change the distance between the antenna and the developer carrying member.

According to the invention described in claim 1, when the distance between the antenna and the developer carrying member is changed according to the expansion and contraction of the humidity sensitive means, the environmental humidity in which the apparatus main body is placed changes. Also in the case of (1), it is possible to accurately detect the amount of the developer by reducing the change in the electrostatic capacitance between the developer carrier and the antenna.

According to a second aspect of the present invention, there is provided a developer container containing a developer, and a developer rotatably disposed in a lower opening of the developer container and supplying the developer to an image carrier. The carrier, the antenna disposed in the developing container in the vicinity of the developer carrier, and the capacitance between the developer carrier and the antenna to detect a capacitance and to output a corresponding output signal. In a developing device provided with an amount detecting means and a control means for issuing an alarm when the value of the output signal becomes equal to or less than a preset value, the humidity of the environment in which the developing device is placed is detected and the humidity is measured according to the humidity. Environmental humidity detecting means for outputting a signal, a variable resistance provided between the remaining amount detecting means and the control means, and a resistance of the variable resistance according to the signal output by the environmental humidity detecting means. Resistance control means to control the value and Characterized by comprising.

According to the second aspect of the invention, a variable resistor is provided between the remaining amount detecting means and the control means, and the resistance value of the variable resistor is controlled according to the signal output by the environmental humidity detecting means. Thus, when the environmental humidity in which the apparatus main body is placed changes, it is the output signal of the remaining amount detection circuit that is input to the control means by detecting the degree of change and applying a load commensurate with it. The fluctuation of the antenna voltage can be suppressed, and the amount of the developer can be accurately detected.

According to a third aspect of the present invention, there is provided a developer container containing a developer, and a developer rotatably disposed in a lower opening of the developer container and supplying the developer to an image carrier. A carrier, an antenna disposed in the developer container in the vicinity of the developer carrier, and a remaining amount for detecting a capacitance between the developer carrier and the antenna and transmitting a corresponding output signal. In a developing device including a detection unit and a control unit that issues an alarm when the value of the output signal is equal to or less than a preset value, a change in environmental humidity between the remaining amount detection unit and the control unit. A humidity sensitive resistor whose resistance value changes according to the above is provided, and the output signal is corrected according to the environmental humidity.

According to the third aspect of the present invention, by providing the humidity sensitive resistor between the remaining amount detecting means and the control means,
Even when the environmental humidity in which the apparatus body is placed changes, it is possible to accurately detect the amount of the developer by reducing the fluctuation of the antenna voltage which is the output signal of the remaining amount detecting means input to the control means. .

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

First Embodiment FIG. 1 shows the first embodiment of the present invention.
1 is a schematic configuration diagram of a developing device according to an embodiment. In the figure, the developing container, the stirring member, and the developing blade are the same as the conventional ones, and are therefore omitted to simplify the drawing. The equivalent circuit of the toner detecting portion of this embodiment is the same as that of the conventional one shown in FIG. The developing device of the present embodiment includes a developing sleeve 2 which is a developer carrying member, an antenna 1 for detecting the remaining amount of toner, a movable supporting portion 30 which rotatably supports the antenna 1, and a volume that expands due to humidity. Moisture-sensitive member 33 as a moisture-sensitive member that contracts, and moisture-sensitive member 33
And a holding unit 34 that holds the. In addition, the developing device of the present embodiment is a CPU that controls the entire device, such as a control that issues an alarm when the toner remaining amount becomes less than or equal to a preset value.
(Control means).

The antenna 1 is fixed to the movable support portion 30 so as to be rotatable between a position a shown by a solid line and a position b shown by a dotted line. The movable support portion 30 has a shaft 30a and a rotating piece 30b rotatably supported by the shaft 30a.
The rotating piece 30b is formed in a disc shape having a notch portion with a notch angle of about 90 degrees. The rotating piece 30b is a shaft 30a.
May be provided at both ends of the shaft 30a, or may be provided at only one end of the shaft 30a. Also, the antenna 1 is attached to the rotating piece 30b.
Has been attached. At one end 30c of the cutout portion of the rotating piece 30b, one end of a moisture sensitive member 33 whose volume expands and contracts due to humidity is attached directly or through the member. Holding part 34
Has a floor portion 34a fixed to the developing container and a standing piece 34b provided at the left end of the floor portion 34a. The other end of the moisture sensitive member 33 is attached to the standing piece 34b of the holding portion 34 directly or through the member.

Next, the operation of the first embodiment will be described. When the apparatus main body is placed in a low humidity environment, the humidity sensitive member 33 is in a contracted state, and the position of the antenna 1 is supported at the position a. When a developing bias is applied to the developing sleeve 2, the antenna 1 has the developing sleeve 2
A charge corresponding to the amount of toner between the antenna 1 and the antenna 1 is induced,
By monitoring the output, the amount of toner near the developing sleeve 2 can be detected.

By the way, in the conventional apparatus, when the environment in which the apparatus main body is placed becomes high in humidity, the AC voltage of the developing bias becomes low, and the output from the antenna 1 becomes low as it is, which is lower than the actual amount of toner. It will be detected when there are few. However, in the present embodiment, the humidity sensitive member 33 expands due to the high humidity environment and pushes the movable support portion 30 in the arrow X direction. The movable support portion 30 is rotated by being pushed,
The antenna 1 attached to the movable piece 30a moves to the position of b. As a result, the distance between the developing sleeve 2 and the antenna 1 is narrowed, and the antenna voltage is increased. Therefore, the value of the antenna voltage that has become low in output due to high humidity can be corrected, and the amount of toner can be appropriately detected.

Here, the moisture sensitive member means a member whose volume expands and contracts depending on humidity, and the moisture sensitive member 33 expands and contracts depending on the moisture absorption of nylon resin, polyester resin, wood chips, and the like. Use members.

An example of the actual output value is as follows:
When the environmental humidity changed from low humidity to high humidity and the AC component of developing bias decreased by Δ100V, the antenna voltage decreased by Δ0.5V.
Therefore, when the antenna 1 is moved closer to the developing sleeve 2 by 0.5 mm by the method of the present embodiment, the antenna voltage increases by Δ0.5V, and the antenna voltage is corrected with respect to the toner amount.

In the apparatus of this embodiment, when the humidity becomes low again, the moisture sensitive member 33 contracts and the position of the antenna 1 is returned to the position a. Therefore, according to the present embodiment, it is possible to accurately detect the toner amount even if the environmental humidity changes, and therefore, when the toner amount is low, a display for notifying the replacement time of the cartridge is provided,
It is possible to accurately perform an alarm operation such as stopping the device body.

Next, a modification of the first embodiment will be described. FIG. 2 is a diagram showing a modification of the first embodiment.
The developing device shown in FIG. 2 differs from the developing device shown in FIG. Since other parts are substantially the same as those shown in FIG. 1, those having the same functions as those shown in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted. In this modification, a member 36 such as animal hair having a property of lengthening / shortening in accordance with a change in humidity is used as the humidity sensing means. Further, in this modification, the movable piece 30
A spring 32 for urging b in the direction of arrow X is provided. This spring 32 has one end 30c of the cutout portion of the movable piece 30b.
The other end is attached to the upright piece 34b of the holding portion 34. A member 36 such as animal hair is stretched by a spring 32 between one end 30c of the cutout portion of the movable piece 30b and the standing piece 34b of the holding portion 34.

In the case of the above modification, the antenna 1
Is in the position of a, but when the member 36 such as animal hair expands due to high humidity, the movable piece 30b of the movable support member 30 is rotated in the X direction by the urging force of the spring 32, and the antenna 1 moves to the position of b. Move to position. On the other hand, when the member 36 contracts due to low humidity, the spring 32
The movable piece 30b rotates in the direction opposite to X against the urging force of
The antenna 1 moves to the position a. As a result, also in this modification, the position of the antenna 1 can be moved according to the change in the environmental humidity, and the toner amount can be accurately detected.

The present invention is not limited to the above embodiment, and various modifications can be made within the scope of the present invention. For example, the humidity sensing means, the movable supporting portion, the spring and the holding portion, and the arrangement thereof are not limited to the examples shown in FIGS. 1 and 2, and the point is that the developing sleeve 2 and the antenna are changed in accordance with the change in environmental humidity. Anything that automatically changes the positional relationship of 1 may be used.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a diagram showing an equivalent circuit of the toner amount detection unit of the developing device of this embodiment. The present embodiment differs from the conventional device in that the present embodiment includes a variable resistor 40, a humidity sensor 42, and a resistance control device 44. Other points are the same as the conventional ones. Therefore, the schematic configuration diagram of the present developing device is shown in FIG.
Since it is the same as the conventional one shown in FIG. Also,
In FIG. 3, components having the same functions as those shown in FIG. 6 are designated by the same reference numerals, and detailed description thereof will be omitted.

In the present embodiment, a variable resistor 40 connected in series between the remaining amount detection circuit 14 and the CPU, a humidity sensor 42 for detecting environmental humidity, and an output from the humidity sensor 42 are provided. A resistance control device 44 for controlling the value of the variable resistance 40.

Next, the operation of this embodiment will be described. At the time of image formation, when the operation of the developing device 3 is started and a developing bias is applied to the developing sleeve 2 from the AC power source 22, charges are induced in the antenna 1 arranged in parallel with the developing sleeve 2. , The current begins to flow. At the same time, the humidity sensor 42 detects the environmental humidity in which the device is placed and sends a signal to the resistance control device 44. The resistance control device 44 changes the resistance value of the variable resistor 40 according to the signal from the humidity sensor 42. An output corresponding to the amount of toner in the developing container is input to the remaining amount detection circuit 14. This signal is the remaining amount detection circuit 14
DC voltage (antenna voltage) of about several V is rectified and stepped down.

Now, for example, when the humidity of the environment in which the apparatus is placed becomes high, the AC component of the developing bias has a lower voltage than in the low humidity condition. Therefore, when compared in the state of the same toner amount, a voltage value lower in high humidity is input to the remaining amount detection circuit 14. However, when the environmental humidity is high, the value of the variable resistor 40 is changed to a low value by the resistance control device 44, so the voltage drop due to the variable resistor 40 of the antenna voltage rectified / stepped down by the remaining amount detection circuit 14 is: Less than in low humidity. Conversely, when the environmental humidity is low, the voltage input to the remaining amount detection circuit 14 increases, but in this case, the value of the variable resistor 40 has been changed to a high value by the resistance control device 44, so the remaining amount detection circuit The voltage drop due to the variable resistor 40 of the antenna voltage rectified and stepped down by 14 is larger than that under high humidity. Therefore, according to the present embodiment, even when the environmental humidity changes, the antenna voltage can be corrected according to the change in the environmental humidity, and the toner amount can be accurately detected. Other functions and effects are similar to those of the first embodiment.

[Third Embodiment] Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a diagram showing an equivalent circuit of the toner amount detecting portion in the developing device of this embodiment. This embodiment differs from the conventional device in that
The present embodiment is provided with the humidity sensitive resistor 26 whose resistance value changes according to the change of environmental humidity. Other points are the same as the conventional ones. Therefore, the schematic configuration diagram of the present developing device is the same as the conventional one shown in FIG. Further, in FIG. 4, components having the same functions as those shown in FIG. 6 are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 4, the moisture-sensitive resistor of this embodiment
26 is provided in series between the remaining amount detection circuit 14 and the CPU (control means), and is represented as a variable resistor. Here, the humidity-sensitive resistor means one whose resistance value changes in accordance with the change in environmental humidity, and as the humidity-sensitive resistor, for example, a polymer material in which carbon is dispersed can be used,
In that case, the resistance value can be finely adjusted by the dispersion ratio of carbon. Similarly, ceramics and the like have the property that the electrical conductivity changes due to changes in humidity when the conductive material is dispersed, and thus can be used as a humidity sensitive resistor. The material of the humidity sensitive resistor is not limited to the above, and any material may be used as long as the resistance value changes in accordance with the change in environmental humidity.

Next, the operation of this embodiment will be described. At the time of image formation, when the operation of the developing device 3 is started and a developing bias is applied to the developing sleeve 2 from the AC power source 22, electric charges are induced in the antenna 1 arranged in parallel with the developing sleeve 2. , The current begins to flow. An output corresponding to the amount of toner in the developing container is input to the remaining amount detection circuit 14. This signal is rectified and stepped down by the remaining amount detection circuit 14 and output as a DC output (antenna voltage) of about several V.

Now, a case in which the humidity in which the developing device is placed is low as a default will be described. When the environmental humidity is high, the AC component of the developing bias has a lower output than when the humidity is low. Therefore, in the state where the humidity sensitive resistor 26 is not provided, when compared in the state of the same toner amount, a lower humidity value is input to the remaining amount detection circuit 14, and the antenna voltage decreases. On the other hand, in the present embodiment, the humidity sensitive resistor 26 is provided, and since the humidity sensitive resistor 26 is in a state where the resistance value is lowered due to the high humidity environment, the humidity sensitive resistor of the antenna voltage is The voltage drop due to 26 is less than in low humidity. On the contrary, when the environmental humidity is low, the antenna voltage rises, but the resistance value of the humidity sensitive resistor 26 is increased due to the low humidity environment. The drop is greater than in high humidity. Therefore, by adjusting the value of the humidity sensitive resistor 26 to an appropriate value, even if the environmental humidity changes, the antenna voltage can be corrected according to the change and the toner amount can be accurately detected. Further, according to the present embodiment, since a substance whose resistance value automatically changes according to the state of environmental humidity is used, a humidity sensor, a resistance control device, etc. are not required, and therefore, the purpose is simple. Can be achieved. Other functions and effects are similar to those of the first embodiment.

The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the gist of the present invention.

[0036]

As described above, according to the developing device of the present invention, even if the developing voltage is increased or decreased due to a change in the environmental humidity in which the main body of the device is placed, the antenna voltage of the remaining amount detection signal By correcting the variation, it is possible to detect the toner amount with higher accuracy.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a developing device according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram for explaining another example of the first embodiment of the present invention.

FIG. 3 is a diagram showing an equivalent circuit of a toner amount detection portion of a developing device which is a second embodiment of the present invention.

FIG. 4 is a diagram showing an equivalent circuit of a toner amount detection portion of a developing device which is a third embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of a conventional developing device.

FIG. 6 is a diagram showing an equivalent circuit of a toner amount detecting portion in a conventional developing device.

[Explanation of symbols]

1 Antenna 20 DC power supply 2 Development sleeve 22 AC power supply 3 Development device 24 Condenser 4 Development container 26 Moisture sensitive resistor 6 Development blade 30 Movable support 8 Photosensitive drum 31 Shaft 10 Cleaning device 32 Spring 12 Stirring member 33 Moisture sensitive member 14 Remaining Quantity detection circuit 40 Variable resistance 16 Antenna as an electrode 42 Humidity sensor 18 Development sleeve as an electrode 44 Resistance control device

Claims (3)

[Claims] 1. A developer container containing a developer, a developer carrier rotatably disposed in a lower opening of the developer container and supplying the developer to an image carrier, and a developer container in the developer container. An antenna arranged in the vicinity of the developer carrying member, and a remaining amount detecting means for detecting the remaining amount of the developer by detecting the electrostatic capacitance between the developer carrying member and the antenna. In the developing device, the movable supporting means for supporting the antenna so that the distance between the antenna and the developer carrier can be changed, and the antenna and the antenna by reversibly expanding and contracting in response to a change in environmental humidity. A developing device, comprising: a moisture-sensitive unit that changes a distance from a developer carrying member. 2. A developer container containing a developer, a developer carrier rotatably disposed in a lower opening of the developer container and supplying the developer to an image carrier, and a developer container in the developer container. An antenna disposed in the vicinity of the developer carrying member, a remaining amount detecting means for detecting a capacitance between the developer carrying member and the antenna, and outputting a corresponding output signal, and the output signal In a developing device having a control means for issuing an alarm when the value of is less than or equal to a preset value, environmental humidity detection for detecting the humidity of the environment in which the developing device is placed and outputting a signal according to the humidity. Means, a variable resistance provided between the remaining amount detection means and the control means, and resistance control means for controlling the resistance value of the variable resistance according to the signal output by the environmental humidity detection means. Development characterized by having apparatus. 3. A developer container containing a developer, a developer carrier rotatably arranged at a lower opening of the developer container and supplying the developer to an image carrier, and a developer container in the developer container. An antenna disposed in the vicinity of the developer carrying member, a remaining amount detecting means for detecting an electrostatic capacitance between the developing carrier and the antenna, and outputting a corresponding output signal; In a developing device including a control unit that issues an alarm when the value becomes equal to or less than a preset value, a resistance value changes between the remaining amount detection unit and the control unit according to a change in environmental humidity. A developing device comprising a humidity sensitive resistor, and correcting the output signal according to environmental humidity.