JPS59189367A - Developing device - Google Patents

Abstract

PURPOSE:To prevent a developer from being deposited almost in the middle between electrodes and to improve the conveyance performance of the developer by improving the shape of electrodes of a developing device which conveys the developer to a picture to be developed by moving the developer among the electrodes. CONSTITUTION:A plate type toner carrier 19 is provided in a toner container 16 provided facing the photosensitive drum 11 of an electronic copying machine. A copper-made electrode group 20 formed linearly is provided on the surface of the toner carrier 19 at equal intervals in parallel to the axial direction of the photosensitive drum 11. On the other hand, the electrode group 20 is applied with a potential which varies successively with time to generate an alternating electric field which has progressive waveform from the left to the right on the surface of the toner carrier 19, and toner is conveyed by its operation among electrodes on oscillation, floating, and smoke basis. In this case, and surfaces of respective electrodes are made hemispherical to obtain a distribution of lines of electric forces among the electrodes as shown by dotted lines in a figure, and the lines of electric force operate to contribute the movement of the toner effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel developing device for developing an electrostatic latent image formed on a photoreceptor drum in a non-contact manner, for example in an electronic copying machine.

[Technical background of the invention and its problems]

Conventionally, the magnetic brush development method, cascade development method, fur brush development method, etc. are well known as methods for developing electrostatic latent images, but recently new development methods that are completely different from these methods have been studied. .

For example, as shown in FIG.
A toner carrier 3 having linear electrode groups 2 arranged at regular intervals on its surface is provided facing the toner carrier 3, and a time-varying potential is sequentially applied to the electrode groups 2 to create an alternating electric field between each electrode. By generating this, the non-magnetic toner 4 is moved between each electrode along the direction in which the electrodes are arranged, and is also caused to rise toward the photoreceptor drum 1 according to the lines of electric force, thereby eliminating vibration, floating, and smoke. The toner 4 is conveyed by moving while changing the toner 4, and supplies the toner 4 to the electrostatic latent image on the photoreceptor drum 1.

However, this developing method had the following problems. That is, as shown in FIG. 2, when a potential is applied to the electrode group 2 in a portion of the photosensitive drum 1 that does not face the electrostatic latent image surface, the lines of electric force become like broken lines. In other words, the electric field is strong between the electrodes, but it is almost nonexistent near the center of the electrodes. As a result, although the toner moves between the electrodes under strong force, it receives almost no force on the electrodes, and the toner 4 remains piled up in a mountain shape as shown in FIG. The toner 4 accumulated in a mountain shape obstructs the movement of the moving toner T, and eventually toner transportation stops.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its purpose is to prevent the developer from accumulating near the center of the electrode, so that the movement of the developer is not hindered. It is an object of the present invention to provide a developing device in which the conveyance of the developer is improved and the developer is conveyed reliably and smoothly.

[Summary of the invention]

The present invention moves the developer between the electrodes by applying a potential that changes over time to a group of electrodes provided near the surface to be developed and at least a portion of which faces the surface to be developed. In a developing device that conveys developer to a surface to be developed,
By shaping the poles of the above electrode group so that the center is higher than the ends in the direction of movement of the developer, the lines of electric force can effectively contribute to the movement of the developer. It is meant to work.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 4, reference numeral 11 denotes a photosensitive drum of, for example, an electronic printer, which rotates in the direction of arrow a in the figure.

The photosensitive drum 11 has a selenium-tellurium based photosensitive layer 1 as an image carrier on the surface of an aluminum drum 12.
3 is formed, and a negatively charged electrostatic latent image 14 is formed on the photosensitive layer 13, for example. Note that the drum 12 is grounded. However, photoreceptor drum 1
A developing device 15 according to the present invention is provided opposite to the developing device 1, and is configured as follows. That is, a toner container 16 stores non-magnetic toner 17 as a developer. This toner container 16 has a photosensitive drum 11 on its upper surface.
An opening 18 is formed at a portion opposite to the opening 18, and the bottom surface thereof is formed as an inclined surface that descends from the right end toward the left end in the drawing. The above toner container 1
A plate-shaped toner carrier 19 is provided inside the toner carrier 6 .

The toner carrier 19 has a horizontal portion 19a and an inclined portion 19b that bends downward from a substantially central portion and descends toward the left end. The horizontal portion 19a faces the surface of the photoreceptor drum 1 through the opening 18 of the toner container 16, and the distance from the surface of the photoreceptor drum 11 is approximately 2.0.
It is maintained at wn. Further, the end portion of the inclined portion 19b is immersed in the toner 17. On the surface of the toner carrier 19, a group of copper electrodes 20 are provided which are arranged parallel to the axial direction of the photoreceptor drum 11 at equal intervals and each formed in a linear shape. Each electrode of this electrode group 20 is formed into a chevron shape with a substantially hemispherical end face, for example, as shown in FIG. 5, and the electrode width is approximately 0.1 mm.
~0.5m, and the electrode spacing is maintained at approximately 0°1~0.5cm. Note that 21 is a stirrer for stirring the toner 17.

Now, each electrode of the electrode group 20 configured as described above is connected and grouped, for example, as shown in FIG. 6. That is, for example, eight groups n. The electrodes are divided into 1 to 3, and the electrodes belonging to one electrode group are connected every eight. And each electrode group n.

A voltage is applied to n7 by a control circuit shown in FIGS. 7 to 9, and the details thereof will be explained below.

7 to 9 show a control circuit that controls the application of voltage to the electrode group 20 grouped as shown in FIG. 6. First, FIG. 7 schematically shows the overall configuration, and includes a reference oscillator 31 that determines the scanning speed of the voltage applied to the electrode group, a counting operation performed by pulses output from this oscillator 31, and a series of voltage scanning An octal counter 32 controls the cycle, and voltage control codes vCoo to ■Co3. vCl.

~vC131vC2o-vC231vC3o-VC53
,■C4o~■C43゜6- VC5o-VC53,vC6o~■C63,■C7o~
■Voltage control code generation circuit 33 that generates c73, and each voltage control code from this voltage control code generation circuit 33 generates a voltage Eno """ E corresponding to each code.
It is constituted by a control voltage generation circuit 34 that generates n7 and applies it to the electrode group 2θ.

FIG. 8 shows the voltage control code generation circuit 33 in detail, in which a decoder 35 decodes the output of the counter 32, each output end of the decoder 35 is connected in series,
Each electrode group n.

Code generation circuit 3 that generates voltage control code to ~n7
68 to 367. Each of the code generation circuits 36o to 367 is configured by a diode matrix circuit (ROM), for example, and stores an output code corresponding to an address in advance, and the output code changes as the address specified by the counter 32 changes. It looks like this.

FIG. 9 shows the control voltage generation circuit 34 in detail, which generates voltages Eno to E n 7 corresponding to each voltage control code from the voltage control code generation circuit 33, and generates voltages Eno to E n 7 corresponding to each voltage control code from the voltage control code generation circuit 33, and each electrode glue 7''no -n 7 respectively.The voltage generation circuits 378 to 377 are configured by voltage control codes (for example,
A transistor Q for output voltage control turns on and off in response to coo~■co3). -Q3, these transistors Q; -Resistors R1 to R8 for operating Q3, and the above transistor Q. It is constituted by resistors R7 to R1□ that divide the power supply voltage E according to the on/off operation of Q3.

Note that the above-mentioned resistors R2 to R12 are, for example, if the value of the resistor "10" is R, the resistors R2 and R11 are 3R, and the resistor R1 is
2 is set to 9R, respectively. Here, the voltage control code (for example, vCo
The relationship between the output voltage (Eno) and the output voltage (Eno) is shown in the table below.

In the above table, the way the voltage control code vCoo-vco5 is given to the control voltage generation circuit 34 is in five modes M.
O-M4, and the value of the output voltage En o in each mode is o, 1. /4E, 1/2E, 3/4E
There are five voltage values: , E. The same holds true for the relationships between other voltage control codes and output voltages.

By the control circuit as described above, potentials in a distribution state as shown in FIG. 10 are applied to each electrode of the electrode group 20, for example. In addition, n01 + nll + n21 in the figure
+ n31 r n41 r n51 r n61 r
n711=. indicates each electrode. That is, at one moment, the potential distribution is as shown by the dashed line hO, at the next moment, the potential distribution is as shown by the solid line a1, and at the next moment, the potential distribution is as shown by the broken line a2. , at the next instant, a potential distribution that shifts further to the right, and so on, is given a potential distribution that changes sequentially to the right.As a result, the toner will eventually move from left to right on the drawing. become. By sequentially applying the above-mentioned potentials to the electrode group 2o, an alternating electric field with a waveform traveling from left to right is generated on the surface of the toner carrier 19, and due to the action of the alternating electric field, Toner is transported between electrodes while being vibrated, suspended, and smoked.

In this way, development is performed by conveying the toner. That is, since the left end portion of the toner carrier 19 is immersed in the toner 17, the toner carrier 19
The toner 17 is always present at the left end of the toner carrier 1.
It is positively charged due to friction with 9. therefore,
Due to the generation of the above-mentioned alternating electric field, the toner 17 is conveyed to the right along the inclined portion 19b of the toner carrier 19 while vibrating, floating, and becoming smoked between the electrodes, and is transferred to the horizontal portion 19a. By being attracted to the electrostatic latent image 14 on the photoreceptor drum 11, the electrostatic latent image 14 is developed.

The toner that does not contribute to development is further conveyed to the right and falls downward at the right end of the toner carrier 19. The fallen toner moves to the lower left under the action of gravity along the inclined surface of the bottom of the toner container 16, returns to the left end of the toner carrier 19, and is stirred by the stirrer 21.

In the developing device as described above, by forming each electrode of the electrode group 20 into the shape described above, a distribution of electric lines of force as shown by broken lines in FIG. 5 can be obtained between each electrode. That is, the lines of electric force extend to the vicinity of the center of each electrode, so that the lines of electric force effectively contribute to the movement of the toner. The situation is first
This will be explained in more detail using FIG. Figure 11 schematically shows the movement of toner near the electrodes. By making each electrode into the shape described above, the electric lines of force become distributed as shown by the broken lines, and the toner is almost moved by this electric force. move along the lines of force. For example, toner near the hem of the electrode receives the strongest force because the electric field is strongest near it. Therefore, the toner bounces strongly, flies high, and moves. The toner near the top of the electrode mostly moves along the lines of electric force. In this way, the electric lines of force act to effectively contribute to the movement of the toner, and as a result, the toner does not accumulate in the center of each electrode, and the movement of the toner moving in the lateral direction is prevented. Toner can be transported reliably and smoothly without any obstruction.

In the above embodiment, each electrode was formed into a chevron shape with an approximately hemispherical end face, but for example, it may be formed into a chevron shape, which is approximately trapezoidal as shown in FIG. 12, or approximately trapezoidal as shown in FIG. 13. It may be formed into a chevron shape that is an isosceles triangle, and even in this case, the same effects as in the above embodiment can be obtained.

Further, in the above embodiment, the case where the invention is applied to the developing device of an electronic copying machine has been described, but the present invention is not limited to this, and can also be applied to the developing device of various image recording devices that use electrostatic latent images. Applicable.

〔Effect of the invention〕

As detailed above, according to the present invention, it is possible to prevent the developer from accumulating near the center of the electrode, thereby preventing the developer from interfering with the movement, and further improving the developer transportability. Thus, it is possible to provide a developing device in which developer is transported reliably and smoothly.

[Brief explanation of drawings]

Figures 1 to 3 are for explaining the developing method that has been studied in the past. Figure 1 is a schematic diagram of the developing device, Figure 2 is a diagram showing the distribution of electric lines of force between electrodes, and Figure 2 is a diagram showing the distribution of electric lines of force between electrodes. Figure 3 shows the state in which toner is deposited near the center of the electrode, and Figures 4 to 11 are not intended to explain one embodiment of the present invention, so Figure 4 shows the overall configuration. Figure 5 is a diagram showing the shape of the electrodes and the distribution of electric lines of force between the electrodes, Figure 6 is a diagram showing the connection state of the electrode group, and Figure 7 is a diagram showing the application of voltage to the electrode group. A schematic configuration diagram of the control circuit that performs control, FIG. 8 is a configuration diagram of the voltage control code generation circuit in FIG. 7, FIG. 9 is a configuration diagram of the control voltage generation circuit in FIG. 7, and FIG. FIG. 11 is a diagram schematically showing the movement of toner near the electrode, and FIGS. 12 and 13 are diagrams showing electrode shapes in other embodiments of the present invention. . 1 No... Photosensitive drum, 14... Electrostatic latent image, 15...
Developing device, 16 Toner container, 17 Non-magnetic toner, 19 Toner carrier, 20 Electrode group, 31 Oscillator, 32 Counter, 33...・
Voltage control code generation circuit, 34... control voltage generation circuit. Applicant's representative Patent attorney Takehiko Suzue 14- Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 C

Claims (1)

[Claims] By applying a potential that changes over time to a group of electrodes provided near the surface to be developed and at least a portion of which faces the surface to be developed, the developer is moved between the electrodes and the surface to be developed is What is claimed is: 1. A developing device for transporting developer to a developer, wherein each electrode of the electrode group has a shape in which a central portion thereof is positioned higher than an end portion with respect to a moving direction of the developer.