JPH07132636A - Image forming apparatus - Google Patents

Abstract

PURPOSE:To provide an inexpensive image forming apparatus capable of obtaining high toner supply efficiency and high toner control efficiency using low control voltage. CONSTITUTION:An aperture electrode 1 is obtained by forming a plurality of apertures 6 to an insulating sheet 2 and forming control electrodes 4 with a thickness of 1mum on the single surface of the sheet 2 at every apertures 6 and a toner repulsive pattern smoothing layer having the same thickness as the control electrodes only to a non-pattern part excepting the control electrodes 4 and the wiring parts thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus which can be used in copying machines, printers, plotters, facsimiles and the like.

[0002]

2. Description of the Related Art Conventionally, as one of image forming apparatuses, an electrode having a plurality of openings (hereinafter referred to as apertures) is used, and a voltage is applied to the electrode based on image data. U.S. Pat. No. 3,689,935 discloses controlling toner particles so that they can pass through the aperture and forming an image on a support by the toner particles that have passed.

This image forming apparatus comprises a flat plate made of an insulating material, a continuous reference electrode formed on one surface of the flat plate, and a plurality of control electrodes insulated from each other formed on the other surface. , An aperture electrode body having at least one row of apertures formed through each of the control electrodes, and a means for selectively applying a potential between the reference electrode and the control electrode. A means for supplying charged toner particles so that the flow of toner particles passing through the aperture is modulated by an electric potential, and a means for positioning the support in the particle flow path so that the support and the aperture electrode body can move relative to each other. It consists of and.

Also, for example, US Pat. No. 4,743,926.
Nos. 4,755,837, 4,780,733, and 4,847,796 disclose an image forming apparatus in which an aperture electrode body is arranged with a control electrode on the support side and a reference electrode on the toner supply side. There is.

In contrast, US Pat. No. 4,912,489
In the specification of the above U.S. Pat. It is described that it can be suppressed to about 1/4 as compared with the image forming apparatus.

Here, the "off" means a time when the toner particles are not attached to the support, that is, a time when a blank portion of an image is formed, and conversely, "on" means that the support is on the support. It means a time point when a toner image is formed on.

[0007]

However, in the conventional image forming apparatus as described above, the distance between the toner supply means and the aperture electrode body is large, and therefore, the density of the supplied toner per time, that is, the toner supply. The efficiency is considerably lower than that of the toner supply system in the conventional electrophotographic system, and a considerably large control voltage is required to obtain a predetermined image density.

On the other hand, in the above conventional image forming apparatus, when the distance between the toner supply means and the aperture electrode body is simply reduced, the toner adheres to the toner flow control means,
This caused the aperture to be clogged. Especially when the aperture electrode body is arranged with the reference electrode on the support side and the control electrode on the toner supply side,
Without the protective layer of the control electrode, the gap between the toner supply means and the control electrode becomes too small, and in some cases, the gap may come into contact with each other, causing discharge or short circuit in synchronization with the ON / OFF cycle of the control voltage. This causes a new problem that the drive circuit of the control electrode is destroyed. However, the presence of this protective layer increases the distance between the control electrode and the toner layer, and increases the control voltage required to apply a predetermined control electric field to the toner layer, resulting in an expensive drive with high breakdown voltage. I had no choice but to use an IC.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an inexpensive image forming apparatus capable of obtaining high toner supply efficiency and high toner control efficiency with a low control voltage. Has an aim.

[0010]

To achieve this object, an image forming apparatus of the present invention comprises an insulating substrate having an opening through which charged toner passes, and the insulating substrate is formed on the insulating substrate. The control electrode that controls the passage of the charged toner through the opening and the portion of the insulating substrate where the control electrode is not formed are formed to have the same thickness as the control electrode. Has a toner repulsion pattern smoothing layer configured to be charged to the same polarity, and a toner carrier for carrying the toner, and supplies the toner to the toner flow control means. And a toner supply unit that operates.

The toner carrier may be in pressure contact with the surface of the toner flow control means on which the control electrode is formed via the toner.

[0012]

The image forming apparatus of the present invention having the above structure is
Regardless of the control voltage applied to the control electrode, an electric field is always generated near the surface of the toner flow control means in the direction in which the toner receives a force from the toner repulsive pattern smoothing layer toward the control electrode. A thin layer of toner adheres to the surface, and this serves as a protective layer for holding a gap between the toner carrying member and the toner carrying member, and is used for printing when ON.
Therefore, a short circuit due to discharge or contact between the control electrode and the toner carrying member does not occur. Further, even if the toner flow control means and the toner supply means are arranged such that the toner carrying member and the surface of the toner flow control means having the control electrode are in pressure contact with each other via the toner, Since the unevenness due to the presence of the control electrode is smoothed by the toner repulsive pattern smoothing layer on the surface in contact with the toner carrying member, the toner flow is disturbed and the toner supply amount varies for each aperture. The unevenness of the image density due to the occurrence does not occur.

[0013]

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

FIG. 1 is a diagram showing an outline of the image forming apparatus of the present invention, and FIG. 4 is an enlarged view of the main part of the image forming apparatus of this embodiment. A cylindrical rear electrode roller 22 is rotatably arranged on a chassis (not shown) on the upper side of the aperture electrode body 1 as a toner flow control means with a gap of 1 mm. It is configured to be able to carry the support 20 inserted into the. Further, a toner supply device 10 is arranged below the aperture electrode body 1 along the longitudinal direction of the aperture electrode body 1, and further, a support body conveyed by the back electrode roller 22. A fixing device 26 is disposed at the destination of the movement of 20.

Next, the respective components will be described in detail. In the toner supply device 10, the toner case 11 also serving as a housing of the entire device, the toner 16 housed in the toner case 11, and the supply roller 12 are provided. And a toner carrying roller 14 and a toner layer regulating blade 18. Here, the toner carrying roller 1
Reference numeral 4 is for carrying the toner 16 and carrying it toward the aperture electrode body 1, and the supply roller 12 is for supplying the toner 16 to the toner carrying roller 14.

The supply roller 12 and the toner carrying roller 1
4 is rotatably supported in the toner case 11 in the direction of the arrow shown in FIG.

The toner carrying roller 14 is also connected to a motor (not shown), and the supply roller 12 is also connected to a motor (not shown).
It is driven by the motor.

Further, on the toner carrying roller 14, an insulating spacer 1 made of insulating fine particles such as glass beads is formed.
3 is formed, which serves to prevent the control voltage from being short-circuited due to the contact between the surface of the toner carrying roller 14 and the control electrode 4.

The insulating spacers 13 are evenly formed on the surface of the toner carrying roller 14 by a method such as coating the toner carrying roller 14 with a dispersion of insulating fine particles in a known conductive adhesive or the like. It is distributed and worn.

The toner 16 sent from the supply roller 12 is rubbed against the toner support roller 14 by the rotation of the toner support roller 14 and the supply roller 12 in the direction of the arrow shown in FIG. The toner image is carried on the toner carrying roller 14 by an adhesion force such as a mirror image force and a van der Waals force induced on the surface of the toner carrying roller 14 by this charged electric charge.

The toner layer regulating blade 18 is for adjusting the amount of the toner 16 carried by the toner carrying roller 14 so as to be uniform on the roller surface, and is pressed against the toner carrying roller 14. The toner layer regulating blade 18 may be configured by selecting an appropriate material and connecting a power source so that the toner 16 carried on the toner carrying roller is uniformly charged.

As shown in FIG. 2, the aperture electrode body 1 comprises a polyimide insulating sheet 2 having a thickness of 25 μm and a diameter of 1 mm.
A plurality of apertures 6 of 00 μm are formed in one row, and
A control electrode 4 having a thickness of 1 μm is formed on each surface of the aperture 6 on the surface facing the toner carrying roller 14. Further, the control electrode 4 is a coating layer applied only to the non-patterned portion excluding the wiring portion. And its thickness is the same as the control electrode, 1 μm
And the toner repulsive pattern smoothing layer 5 is formed.

As shown in FIG. 4, the aperture electrode body 1 has the toner carrying roller 1 at the aperture position of the insulating sheet 2 with the control electrode 4 facing the support body 20 side.
It is pressed against 4.

The material of the toner repulsive pattern smoothing layer 5 is, for example, polytetrafluoroethylene, polytrihydrogenated ethylene monochloride, polyvinyl chloride, chlorinated polyester,
Polydiphenylpropane carbonate, polyethylene,
It is possible to select a material such as polyacrylonitrile that is located near the negative end on the known charging train. Further, a combination of materials of the toner 16, the toner carrying roller 14, and the toner repulsive pattern smoothing layer 5 may be selected so that the toner 16, the toner carrying roller 14, and the toner carrying roller 14 are negatively charged.

Here, the positional relationship between the aperture 6 of the aperture electrode body 1 and the toner carrying roller 14 will be described in detail. As shown in FIG. 3, each center line 30 of each aperture 6 has a toner carrying roller 14. It is arranged so as to pass through the uppermost portion of the peripheral surface of and the central shaft 32 of the toner carrying roller 14. According to this, each aperture 6
Based on the uppermost part of the peripheral surface of the toner carrying roller 14,
By arranging them evenly on the left and right, the distribution of the toner 16 passing through each aperture 6 can be made uniform over the entire area of the aperture. In addition, the wall surface of the aperture 6 and the toner 16
Since the flying direction of the toner is parallel to the flying direction of the toner, it is possible to stably fly the toner.

Further, the aperture electrode body 1 itself has an aperture 6 with respect to the toner carrying roller 14 as shown in FIG.
It is pressed so that it bends to the left and right about the same angle. As a result, the contact area between the aperture electrode body 1 and the toner carrying roller 14 can be increased, and the lower periphery of the aperture 6 can be pressed uniformly to the left and right, so that uneven toner concentration is minimized. Can be suppressed.

A control voltage applying circuit 8 is connected between the control electrode 4 and the toner carrying roller 14.
The control voltage application circuit 8 is configured to apply a voltage of 0 V or +50 V to the control electrode 4 based on the image signal.

Further, a DC power source 24 is connected between the back electrode roller 22 and the toner carrying roller 14, and this DC power source is + with respect to the back electrode roller 22.
A voltage of 1 kV can be applied.

Next, the operation of the image forming apparatus configured as described above will be described with reference to FIGS. 1 and 4.

First, by rotating the toner carrying roller 14 and the supplying roller 12 in the direction of the arrow shown in FIG. 1, the toner 16 sent from the supplying roller 12 is rubbed against the toner carrying roller 14 to be negatively charged. The toner is carried on the toner carrying roller 14. Toner 1 carried
After being thinned by the layer regulation blade 18, 6 is conveyed toward the aperture electrode body 1 by the rotation of the toner carrying roller 14. Then, the toner on the toner carrying roller 14 is supplied under the aperture 6 while being rubbed by the insulating sheet 2 of the aperture electrode body 1.

Further, the toner repulsive pattern smoothing layer 5 provided on the surface of the aperture electrode body 1 facing the toner carrying roller 14 is weakened to minus of the same polarity as the toner 16 due to friction with the toner carrying roller 14. Since it is charged and its surface potential reaches about 80 to 200 V, the control electrode 4
Regardless of the voltage applied to the toner repulsive pattern smoothing layer 5, an electric field is always generated in the direction from the surface of the toner repulsive pattern smoothing layer 5 to the surface of the control electrode 4, so that the toner 16 does not depend on the control voltage. Since it adheres in a thin layer and faces the toner carrying roller 14 via this, it does not short-circuit with the toner carrying roller 14 and therefore does not cause problems such as discharge and short circuit.

Further, since the control electrode 4 and the toner repulsive pattern smoothing layer 5 are provided on the surface on which the aperture electrode body 1 and the toner carrying roller 14 slide, there is no step between them, In the image forming apparatus of the present invention, uneven toner supply such as partial excessive toner supply or insufficient toner supply caused by the flow of the layer of the toner 16 conveyed while being pressed against this surface is interrupted by such steps. There is no such thing.

Here, in accordance with the image signal, the control voltage applying circuit 8 adds + to the control electrode 4 corresponding to the image portion.
A voltage of 50V is applied. As a result, an electric force line from the control electrode 4 toward the toner carrying roller 14 is formed in the vicinity of the aperture 6 corresponding to the image portion due to the potential difference between the control electrode 4 and the toner carrying roller 14. As a result, the negatively charged toner receives an electrostatic force in the direction of higher electric potential, passes through the aperture 6 from the toner carrying roller 14, and is drawn out to the control electrode 4 side. The extracted toner 16 further flies toward the support 20 due to the electric field formed between the support 20 and the aperture electrode body 1 by the voltage applied to the back electrode 22, and the toner 16 on the support 20 rises. To form pixels.

A voltage of 0V is applied from the control voltage application circuit 8 to the control electrode 4 corresponding to the non-image portion.
As a result, since no electric field is formed between the toner carrying roller 14 and the control electrode 4, the toner carrying roller 1
The toner 16 on 4 does not pass through the aperture 6 because it is not subjected to electrostatic force.

Further, the support 20 is fed by one pixel in the direction perpendicular to the aperture row while the toner 16 forms one row of pixels on the surface thereof. Then, the toner image is formed on the entire surface of the support 20 by repeating the above process. Then, the formed toner image is fixed on the support 20 by the fixing device 26.

In the image forming apparatus constructed as described above, if the insulating toner is used, the toner carrying roller 14 is used.
The insulation between the control electrode 4 and the control electrode 4 is maintained, and the aperture 6 does not cause dielectric breakdown.

In the above process, since the control electric field by the control electrode 4 is formed between the control electrode 4 and the toner carrying surface of the toner carrying roller 14, when the aperture electrode body 1 having the above construction is used. Since the inter-electrode gap is only the thickness of the layer of the carried toner 16 and the control electric field can be directly applied to the toner 16 existing in this narrow gap, the control efficiency is good and a desired control voltage can be obtained with a small control voltage. Since a control electric field is obtained, a drive element such as an IC provided in the control voltage application circuit 8 for applying a voltage to the control electrode 4 is
It is possible to use an inexpensive one having a low withstand voltage.

Further, since the aperture electrode body 1 and the toner 16 on the toner carrying roller 14 are in contact with each other at the entrance portion of the aperture 6, the toner 16 accumulated at the entrance portion of the aperture 6 is not supported. Since the toner 16 is pushed away by the toner sequentially supplied, the toner 16 does not accumulate and bridge to block the aperture 6.

The present invention is not limited to the embodiments described in detail above, and various modifications can be made without departing from the spirit of the invention.

For example, although the control voltage of the aperture corresponding to the non-image portion is set to 0V in the above embodiment, it may be a negative voltage. In this case, an image with less fogging can be obtained. Further, in the above embodiment, the aperture electrode body is used as the toner flow control means, but it is also possible to use, for example, a knitted electrode body as described in the specification of US Pat. No. 5,036,341.

A suitable insulating spacer may be attached to the surface of the toner carrying member. As a result, it is possible to more reliably prevent a short circuit between the toner carrying member and the control electrode, and at the same time, to periodically peel off the toner adhering to the control electrode to assist the circulation of the toner in the toner supply means.

FIG. 5 is a schematic view showing an image forming apparatus of a modified example having the above structure.

On the toner carrying roller 14, an insulating spacer 13 composed of insulating fine particles such as glass beads is formed, and when the toner runs out, the toner carrying roller 14 is formed.
Even when the toner layer on the upper and control electrodes 4 is gone, short circuit of the control voltage due to contact between the surface of the toner carrying roller 14 and the control electrode 4 is prevented, and the toner 16 adhering to the control electrode 4 is periodically removed. The toner 16 can be peeled off and used again for image formation.

The insulating spacers 13 are evenly formed on the surface of the toner carrying roller 14 by a method of coating the toner carrying roller 14 with a dispersion of insulating fine particles in a known conductive adhesive or the like. It is distributed and worn.

[0045]

As is apparent from the above description, the image forming apparatus of the present invention always applies toner from the surface of the toner repulsive pattern smoothing layer to the surface of the control electrode regardless of the voltage applied to the control electrode. Since an electric field is generated in the direction in which the toner adheres, the toner adheres to the control electrode in a thin layer regardless of the control voltage and faces the toner carrying member therethrough, so that it does not short-circuit with the toner carrying member, and therefore discharge or discharge It does not cause problems such as short circuits.

Further, a control electrode and a toner repulsive pattern smoothing layer are provided on the surface on which the toner flow control means and the toner carrying member slide, and there is no step between them, so there is no difference between them. There is no uneven toner supply such as partial excessive or insufficient toner supply caused by blocking the flow of the toner layer conveyed while being pressed.

As described above, according to the image forming apparatus of the present invention, it is possible to provide an inexpensive image forming apparatus which can obtain high toner supply efficiency and high toner control efficiency with a low control voltage.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment embodying the configuration of an image forming apparatus of the present invention.

FIG. 2 is a perspective view showing a configuration of an aperture electrode body used in the image forming apparatus of the present invention.

FIG. 3 is a diagram schematically showing a configuration of an aperture electrode body and a toner carrying roller used in the image forming apparatus of the present invention.

FIG. 4 is an enlarged view showing a configuration of a main part of the image forming apparatus of this embodiment.

FIG. 5 is an enlarged view showing a configuration of a main part of a modified example of the present invention.

[Explanation of symbols]

 1 Aperture electrode body 2 Insulating sheet 4 Control electrode 5 Toner repulsive pattern smoothing layer 6 Aperture 8 Control voltage application circuit 14 Toner carrier roller 22 Back electrode roller 24 DC power supply

Claims (2)

[Claims] 1. An insulating substrate having an opening through which charged toner passes, a control electrode formed on the insulating substrate for controlling passage of the charged toner through the opening, and the insulating substrate. A toner repulsive pattern smoothing layer which is formed in the same thickness as that of the control electrode only on a portion of the flexible substrate where the control electrode is not formed, and is configured to be charged to the same polarity as the charging polarity of the toner. An image forming apparatus comprising: a toner flow control unit having: and a toner carrier that carries the toner, the toner supply unit supplying the toner to the toner flow control unit. 2. The image forming apparatus according to claim 1, wherein the toner carrier and the surface of the toner flow control means on which the control electrode is formed are in pressure contact with each other via the toner. .