JPH0740581A - Image forming device - Google Patents

Abstract

PURPOSE:To provide a record image with little fogging by forming recesses and projections continuing along the moving direction of a carrier on a face facing a carrier of an electric control means and controlling sufficiently the movement of toner to be fed. CONSTITUTION:Carried toners 6 are transported by the rotation of a toner carrier roller 14, and the toners on the roller 14 are fed under an aperture 6 while being rubbed by an insulating sheet 2 of an aperture electrode 1. At that time, grains of the toner 16 are restricted by a channel section formed on the sheet 2 to provide the extremely orderly state. That is, respective grains of toner are caught in the channel, and the toners of extremely large movement amount or the remaining toners can be controlled by the restriction. In other words, the movement of toners of irregular movement properties gets less, and a toner group of uniform movement properties is formed. The movement of respective tones is controlled in the above-said manner, and irregular toners are not generated. Thus an image of superior recording quality without fogging can be provided.

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. Toner supply means for supplying charged toner particles so that the flow of toner particles passing through the aperture is modulated by the potential, and the support and the aperture electrode body are moved relatively to position the support in the particle flow path. And means.

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, the conventional image forming apparatus as described above has a problem in recording quality. That is, although the electric field is controlled so that the toner does not fly when it is off, some of the toner may fly out and adhere to the support. The applicant examined this cause and found that the kinetic characteristics of the supplied toner was a very important issue.

The present invention has been made in order to solve the above-mentioned problems, and provides an image forming apparatus capable of sufficiently controlling the movement of the supplied toner to obtain a recorded image with less fog. The purpose is to do.

[0009]

In order to achieve this object, an image forming apparatus of the present invention is provided with a carrier that carries charged particles and supplies the charged particles, and the carrier and the charged particles. An electric field control means for directly controlling the charged particles by an electric field, and a counter electrode arranged with the electric field control means and the image receptor interposed therebetween, and further, a surface of the electric field control means facing the carrier. Concavities and convexities that are continuous along the moving direction of the carrier are formed on the top.

[0010]

The image forming apparatus of the present invention having the above structure is
The unevenness formed in the electric field control means regulates the movement of the supplied toner, and drastically reduces the toner in an uncontrollable movement state. This makes it possible to sufficiently control the flight of the toner by the electric field and obtain a good image quality with high contrast.

[0011]

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

FIG. 1 is a diagram showing an outline of an image forming apparatus of the present invention. A cylindrical rear electrode roller 22 having a gap of 1 mm above the aperture electrode body 1 as an electric field control means. Is rotatably disposed on a chassis (not shown), and is configured to be able to convey the support 20 inserted into the gap. In addition, below the aperture electrode body 1, along the longitudinal direction of the aperture electrode body 1,
A toner supply device 10 is provided, and further, a fixing device 26 is provided at the destination of the support 20 conveyed by the back electrode roller 22.

Next, the respective constituent elements will be described in detail. In the toner supply device 10, the toner case 11 which also serves as a housing of the entire device, and the toner 16 as charged particles contained in the toner case 11 are provided. It comprises a supply roller 12, a toner carrying roller 14, and a toner layer regulating blade 18. Here, the toner carrying roller 14 carries the toner 16 and conveys it toward the aperture electrode body 1, and the supply roller 12 supplies the toner 16 to the toner carrying roller 14.

The supply roller 12 and the toner carrying roller 14 are rotatably supported by the toner case 11 in the direction of the arrow shown in FIG. Further, the toner layer regulating blade 18
Is for adjusting the amount of the toner 16 carried on the toner carrying roller 14 to be uniform on the roller surface and for uniformly charging the toner 16, and is pressed against the toner carrying roller 14. .

As shown in FIG. 2, the aperture electrode body 1 includes a polyimide insulating sheet 2 having a thickness of 25 μm and a diameter of 1 mm.
A plurality of apertures 6 having a size of 00 μm are formed in one row, and a control electrode 4 having a thickness of 1 μm is formed on each of the apertures 6 on the upper surface. And, on the surface of the insulating sheet 2, innumerable grooves are formed in the longitudinal direction. FIG. 4 is a cross-sectional view showing the structure in the vicinity of the surface of the aperture electrode body, which is an essential part of the present invention, in which triangular grooves 3 are formed on the surface. The size of the groove portion 3 varies depending on the particle size and shape of the toner used, but it is sufficient that the groove part 3 has a recess smaller than the toner particle size, for example, a groove of 10 μm or less.

Further, as shown in FIG. 1, 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.

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 is arranged 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.

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
The layer 6 is thinned by the layer regulation blade 18 and charged, and then 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.

At this time, the toner 16 is restrained by the groove portion formed on the insulating sheet 2, and a very uniform movement state can be obtained. That is, each toner is once caught in the groove portion 3, and the toner having a particularly large momentum or the staying toner can be given motion control by the restraint. That is, the amount of toner having abnormal movement characteristics is reduced, and the toner group has uniform movement characteristics.

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, a line of electric force directed from the control electrode 4 to 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 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 applying 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.

At this time, since toner having an abnormal momentum has been conventionally supplied, some toner cannot be controlled by such an electric field and jumps out of the aperture 6. However, since the movement of each toner is uniformly controlled in this embodiment, such abnormal toner does not occur. Therefore, excellent recording quality without image fog can be obtained.

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.

If an insulating toner is used in the image forming apparatus constructed as described above, 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, the control electric field generated by the control electrode 4 is formed between the control electrode 4 and the inside of the aperture 6, and between the aperture 6 and the toner carrying surface of the toner carrying roller 14 which faces the aperture 6. Toner 1
Since the control electric field can be directly applied to 6, the control efficiency is good.

Further, even if a part of the supplied toner 16 receives a mechanical force or the like by sliding with the aperture electrode body 1 and enters the aperture 6 corresponding to the non-image portion, inside the aperture 6 Since it can be controlled so as not to pass through the aperture 6 by the electric field, the toner controllability is good.

Further, since the toner carrying roller 14 and the aperture electrode body 1 are opposed to each other with the toner layer in between, the control voltage can be lowered and the inexpensive drive element can be provided because they can be arranged at a relatively short distance. Can be used.

In addition, the insulating sheet 2 of the aperture electrode body 1
Is directed toward the toner carrying roller 14 side, so that the toner
Even if 6 is not present, the control electrode 4 and the toner carrying roller 14 do not come into contact with each other and electrically short-circuit, and the drive element is not destroyed.

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, in the above embodiment, the control voltage of the aperture corresponding to the non-image portion is set to 0V, but this 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.

In this embodiment, a so-called triangular groove is used, but the present invention is not limited to this. For example,
A groove having a rectangular cross section as shown in FIG. 5 may be used, or a groove having a circular cross section as shown in FIG. 6 may be used.

Further, in this embodiment, the continuous groove portion is formed in the entire width direction of the aperture electrode body, but the present invention is not limited to this. The groove may be formed by being divided into several parts in the width direction, and may be formed only in a part of the upstream side of the toner conveyance.

[0038]

As is apparent from the above description, in the image forming apparatus of the present invention, the concavo-convex pattern which is continuous along the moving direction of the carrier is formed on the surface of the electric field control means facing the carrier. As a result, the movement of the supplied toner is regulated, and the toner in the uncontrollable movement state is drastically reduced. Therefore, it is possible to sufficiently control the flight of the toner by the electric field, and it is possible to obtain a good recorded image with high contrast. .

[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.

4 is a sectional view of the vicinity of the surface of the aperture electrode body shown in FIG.

FIG. 5 is a cross-sectional view showing a first modified example near the surface of the aperture electrode body.

FIG. 6 is a cross-sectional view showing a second modification near the surface of the aperture electrode body.

[Explanation of symbols]

 1 Aperture Electrode 2 Insulating Sheet 3 Groove 4 Control Electrode 6 Aperture 8 Control Voltage Applying Circuit 14 Toner Carrier Roller 22 Back Electrode Roller 24 DC Power Supply

Claims (1)

[Claims] 1. A carrier which carries charged particles and supplies the charged particles, an electric field control unit which is arranged via the carrier and the charged particles, and which directly controls the charged particles by an electric field, and an electric field control unit thereof. In an image forming apparatus provided with a counter electrode arranged with an image receptor interposed therebetween, a concavo-convex pattern that is continuous along the moving direction of the carrier is formed on a surface of the electric field control unit facing the carrier. Image forming apparatus.