JPS60258570A - Developing device - Google Patents

Abstract

PURPOSE:To detect accurately the toner quantity by arranging two induced voltage generating means in different positions of a toner storage part and detecting the voltage difference between respective induced voltages. CONSTITUTION:Electrostatic capacities Ca and Cb to a developing roll 3 of two induced voltage generating means 5 and 6 which are provided in different positions of the storage part of a toner 2 in a developing device body 1 are changed in accordance with the quantity of the toner 2. Voltages Va and Vb obtained by rectifying induced voltages of detecting conductors 5 and 6 by rectifying circuits 12 and 13 are inputted to a differential circuit 14, and a differential voltage Vc is compared with a comparison voltage VSLH to obtain an output voltage Vd. The polarity of the voltage Vd is inverted between a small quantity of toner and an excess quantity, and the voltage Vd is inputted to a motor control circuit 16 of a toner supply device 7 to keep the toner quantity in a certain set value. Since the voltage difference between induced voltages of detecting conductors 5 and 6 is detected, the toner quantity is detected accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a developing device installed in, for example, an electrophotographic copying machine, and more particularly to a developing device capable of detecting the amount of toner contained within its main body.

[Prior art]

Conventionally, as this type of device, 1, for example, Japanese Patent Application Laid-Open No. 58-31
As shown in Japanese Patent Application No. 363, a detection conductor is disposed in the developing unit body facing a developing roller that adheres toner to a recording medium, and the detection conductor is generated by applying an alternating current voltage to the developing roller. An electric field is applied to generate an induced voltage in the single sensing conductor. This induced voltage changes depending on the amount of toner stored in the main body, so
By detecting the change, the amount of toner can be detected.

However, due to the humidity of the toner changing depending on the environment in which the copying machine is used, the dielectric constant differing depending on the type of toner, and the waveform of the AC voltage applied to the developing roller, the sensing conductor The induced voltage generated in the toner fluctuates greatly even when the same amount of toner is stored, and the toner amount cannot be accurately detected.

〔the purpose〕

The present invention has been made in view of the above-mentioned drawbacks, and includes two induced voltage generating means that generate an induced voltage corresponding to the amount of toner in the toner storage portion at different positions within the main body. It is an object of the present invention to provide a developing device that can accurately detect the amount of toner by detecting the amount of toner based on the output of a detection means that detects a voltage difference between respective induced voltages. Furthermore, the developing device further includes a supply means for supplying toner into the main body according to the amount of toner detected as described above.
3. Aiming to provide a developing device that can always hold an appropriate amount of toner in the main body and obtain stable development [Embodiment] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. do.

FIG. 1 is a longitudinal sectional side view showing an embodiment of the present invention, FIG. 2 is a top view of the device shown in FIG. 1, and FIG. 3 is a front view of the device shown in FIG. 2.

In each figure, 1 is a main body of the developing device, and 2 is a single-component toner supplied within the main body 1. Numeral 3 is a magnetic sleeve developing roller (hereinafter simply referred to as developing roller), and 4 is a photosensitive drum serving as a recording medium, on which an electrostatic latent image is formed by well-known charging and exposure operations. Reference numerals 5 and 6 designate two sensing conductors as two induced voltage generating means disposed facing the developing roller 3. The sensing conductor 6 is located above the sensing conductor 5, and each has a coil shape. made of metal.

Reference numeral I denotes a toner supply device as a toner supply means for supplying toner 2 into the main body 1, and 8 is a casing forming the outer shell of the toner supply device 7, in which the toner 2 to be supplied to the main body 1 is housed. . This housing 8 is located above the main body 1, and communicates with the upper part of the main body 1 through a communication portion 8a formed at the lower end. Reference numeral 9 represents a screw serving as a conveying means for transporting the toner 2 stored in the housing 8 to the communication portion 8a, and reference numeral 10 represents a stepping motor that rotates the screw 9. Note that 8b is a lid of the housing 8.

A developing device having the above configuration is 1, for example, JP-A-55-18
The one-component toner jumbing development method described in Japanese Patent No. 656 is adopted. This developing method applies an alternating current bias voltage to the developing roller 3 to obtain development with high contrast and high gradation. Therefore, the developing roller 3 does not generate an electric field within the main body 1, and in this embodiment, the developing roller 3 is used as an electric field generating means.

FIG. 4 is a block diagram showing electrical connections of the developing device. When an AC voltage from the AC bias power supply 11 is applied to the developing roller 3, an induced voltage is generated in the sensing conductor 5.6 disposed opposite the developing roller 3. Also,
Since toner 2 has a dielectric constant that is larger than 1,
The dielectric constant between the developing roller 3 and the sensing conductors 5 and 6 changes depending on the amount of toner 2 between the developing roller 3 and the sensing conductors 5 and 60, and the induced voltage generated in the sensing conductors 5 and 6 changes. . In other words, if we compare the developing roller 3 to one electrode of a capacitor and the sensing conductor 5.6 to the other electrode, a dielectric material is inserted between the electrodes, and the change in the dielectric constant of the dielectric material , this is similar to the change in the induced voltage generated at the other pole.

Among these two detection conductors 5 and 6, one of the detection conductors 6 is arranged at a position further away from the developing roller 3 than the other detection conductor 6, and as shown in FIG. is already completely buried in the toner 2, and the detection conductor 6 is buried in the toner 2 with a toner amount d larger than the toner tb. Depending on the change in the amount of toner 2, the capacitance changes as shown in FIG.

Therefore, the voltage Va obtained by rectifying the induced voltage of the sensing conductor 5 by the rectifying circuit 12 and the voltage Vb obtained by rectifying the induced voltage of the sensing conductor 6 by the rectifying circuit 13 are graphed in relation to the amount of toner as shown in FIG. become that way.

The voltage Va applied to the detection conductor 5 increases as the amount of toner increases, and the amount of toner is already saturated at the voltage v2.

Further, the voltage vb generated by the detection conductor 6 also increases as the amount of toner increases, but the slope of the increase is smaller than that of the detection conductor 5, and the voltage vb gradually saturates to the voltage v2 at the amount d of toner. Voltages Va and V rectified by the rectifier circuits 12 and 13
b are each input to a differential circuit 14 as a detection means, and from this differential circuit 14 a voltage difference V between voltages Va and vb is inputted.
c is output. When this voltage difference Vc is shown in relation to the amount of toner, it becomes a mountain-shaped curve as shown in FIG. Further, the comparison circuit 15 compares the voltage difference Vc with a predetermined comparison voltage V5LI-1. This predetermined comparison voltage VSLH
is set as follows. That is, the amount of toner that is desired to be kept constant in the developing device body 1, for example, the amount of toner C, is set in advance, and the voltage difference VC at that amount of toner C is set as the comparison voltage VSLH. Therefore, comparison circuit 1
The output Vd of No. 5 is inverted at two points, the toner amounts a and C. 9th
The figure shows the state of the output Vd of this comparison circuit 15. When the output Vd is input to the motor control circuit 16 as a control means, in this embodiment the motor control circuit 16 rotates the motor in the shaded area A. The step motor 10 is controlled so as not to rotate in the blank portions A and C. When the step motor 10 rotates, the screw 9 connected to its shaft rotates, and the toner 2 in the toner supply device 7 is sent to the communication portion 8a, and the toner 2 is supplied into the developing device main body 1. .

Note that if the amount of toner supplied into the developing device main body 1 is less than the toner amount a, there will be an inconvenience that the toner 2 will not be supplied into the developing device main body 1. This can be solved by putting toner 2 in the container body 1 in an amount of 8 or more.

〔effect〕

As described above, according to the present invention, two generation means for generating an induced voltage according to the amount of toner in the toner storage section are disposed at different positions within the storage section, and the voltage difference between the respective induced voltages is By detecting the amount of toner based on the output of the detection means that detects the amount of toner, even if the environment in which the copying machine is used, the type of toner, the waveform of the AC voltage applied to the electric field generation means, etc. change, This has the advantage that the amount of toner supplied into the main body can be accurately detected.

Further, by further comprising a supply means for supplying toner into the storage section according to the amount of toner detected as described above, it is possible to always maintain an appropriate amount of toner,
Another effect is that stable development can be obtained.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional side view showing one embodiment of the present invention, FIG. 2 is a front view of the device shown in FIG. 1, FIG. 3 is a top view of the device shown in FIG. 2, and FIG. 5 is an explanatory side view showing the amount of toner supplied into the developing device main body shown in FIG. 1, and FIG. 6 is a block diagram showing the electrical connections of the components shown in FIG. 4. Figure 7 is a diagram showing the capacitance of Ca and Cb in relation to the amount of toner. Figure 7 is a diagram showing the voltage rectified by the rectifier circuit shown in Figure 4 in relation to the amount of toner.
This figure is a diagram showing the output from the differential circuit shown in FIG. 4 in relation to the amount of toner, and FIG. 9 is a diagram showing the state of the output of the comparison circuit shown in FIG. 4. DESCRIPTION OF SYMBOLS 1...Developer main body, 2...Toner, 3...Magnetic sleeve developing roller as an electric field generating means, 4...Photosensitive drum as a recording medium, 5...As an induced voltage generating means Detection conductor, 6... Detection conductor as induced voltage generating means, 7... Toner supply device as toner supply means, 8... Housing, 9... Screw as conveyance means, 10... Step motor, 14... Differential circuit as detection means, Vc... Voltage difference, a, b, c. d...Toner amount Figure 1 Figure 2 Figure 3 h Figure 4 Figure 5 Figure 11 Figure 8 Figure 9

Claims (3)

[Claims] (1) A storage section that stores toner to be deposited on a recording medium, an electric field generation means that generates an electric field within the storage section, and an induced voltage that is coupled to the electric field generation means by capacitance and that corresponds to the amount of toner. two of the induced voltage generating means are arranged at different positions in the storage section, and the amount of toner is determined by the output of a detection means for detecting a voltage difference between the respective induced voltages. A developing device characterized by being configured to detect. (2) A storage section that stores toner to be deposited on a recording medium, an electric field generation means that generates an electric field within the main body, and an induced voltage that is coupled to the electric field generation means by capacitance and that corresponds to the amount of toner. and an induced voltage generating means to generate,
The induced voltage generating means is placed at two different positions within the storage section.
a toner supply means for detecting the amount of toner based on the output of the detection means for detecting the voltage difference between the induced voltages, and further supplying the toner into the storage portion according to the detected amount of toner; A developing device characterized by comprising: (3) The toner supply means includes a casing that communicates with the storage unit, a transport unit that transports the toner stored in the casing into the storage unit, a motor that drives the transport unit, and rotation of the motor. 3. The developing device according to claim 2, further comprising a control means for controlling the detection means according to the output of the detection means.