JPH06155798A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain an image forming device forming a high-quality image at a high pixel forming speed at a low cost. CONSTITUTION:In an aperture electrode body 1 in a title image forming device, a plurality of apertures 6 to 100mum diameter are formed in a line in a 25mum thick insulating sheet 2 made of a polyimide, and a control electrode 4 of 1mum thickness is formed on the top surface for every aperture 6. As shown by a figure 1, the aperture electrode body 1 is depressed against a toner holding roller 14 at the position of the apertures of the insulating sheet 2 with the control electrodes 4 opposed to a substrate 20. A control voltage applying circuit 8 is connected between the control electrodes 4 and the toner holding roller 14. The control voltage applying circuit 8 is so constructed as to apply a 0V or +50V voltage to the control electrodes 4 on the basis of an image signal.

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 Patent Application No. 9469937
No. 926129, No. 140266, and No. 9
The specification of Japanese Patent No. 26158 discloses 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.

On the other hand, in Japanese Unexamined Patent Publication No. 2-226261, the aperture electrode body is arranged so that the reference electrode is on the support side and the control electrode is on the toner supply side. It is described that the applied voltage can be suppressed to about 1/4 of that of the image forming apparatus disclosed in the above-mentioned US patent.

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 image forming apparatus as described above, the electric field inside the aperture is used to control the flow of the charged toner, so the electric field outside the aperture becomes very weak. Was there. Therefore, since the force of drawing the toner supplied under the aperture into the aperture is weak, the toner passing amount per unit time is small and the image forming speed is low. Further, in order to improve the controllability of the toner passing through the aperture, it is necessary to strengthen the electric field in the aperture, which has a drawback that an expensive high-voltage driving element is required.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an image forming apparatus which is inexpensive, has a high pixel forming speed, and can form a high quality image.

[0009]

In order to achieve this object, the image forming apparatus of the present invention controls the passage of the charged toner through the aperture electrode body by using an aperture electrode body having a plurality of apertures, and does not function as a toner supply source. An image is formed on a support located on the opposite side of the aperture electrode body, and an insulating sheet provided on the side of the aperture electrode body facing the toner supply source, A control electrode provided separately for each aperture on the side of the aperture electrode body facing the support and a part of the toner supply source are arranged so as to be in contact with the insulating sheet. And a toner carrier that carries the toner,
A means for forming an electric field according to an image signal is provided between the toner carrier and the control electrode.

[0010]

According to the image forming apparatus of the present invention having the above-mentioned structure, the charged toner carried on the toner carrier is sandwiched between the insulating sheet of the aperture electrode body and the toner carrier and conveyed under the aperture. Here, by applying a control voltage between the control electrode and the toner carrier for each control electrode according to the image signal, an electric field is formed inside the aperture and on the toner carrier below the aperture. The charged toner receives an electrostatic force and passes through the aperture and is deposited on the support or is prevented from passing through the aperture depending on the direction of the electric field.

[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 having a gap of 1 mm on the upper side of an aperture electrode body 1 as a toner flow control means. A chassis 22 (not shown) is rotatably arranged so as to be able to convey the support 20 inserted into the gap. 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 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. As shown in FIG. 1, the aperture electrode body 1 is pressed against the toner carrying roller 14 at the aperture position of the insulating sheet 2 with the control electrode 4 facing the support body 20 side.

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, the center line 30 of each aperture 6 is the 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 attached to the toner carrying roller 14 with respect to the aperture 6 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 application 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 supply roller 12 in the direction of the arrow shown in FIG. 3, the toner 16 sent from the supply 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.

Here, in accordance with an 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, electric lines of force directed from the control electrode 4 to the toner carrying roller 14 are formed near 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 body 20 due to the electric field formed between the support body 20 and the aperture electrode body 1 by the voltage applied to the back electrode 22, and on the support body 20. 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, 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 mechanical force or the like due to 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 interposed therebetween, they can be arranged at a relatively short distance, so that the control voltage can be lowered and an inexpensive driving element can be provided. 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 stitched electrode body as described in JP-A-1-503221.

[0033]

As is apparent from the above description, in the image forming apparatus of the present invention, the insulating sheet provided on the side of the aperture electrode body facing the toner supply source and the support of the aperture electrode body are provided. On the side facing the body, a control electrode that is provided separately for each aperture, and a part of the toner supply source are arranged so as to contact the insulating sheet,
Good toner controllability is provided by including the toner carrier that carries the toner and conveys it, and the means that forms an electric field according to an image signal between the toner carrier and the control electrode. Therefore, the image forming speed is high, the image quality is high, the cost is low, and the reliability is high.

[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 details of an aperture electrode body mounted on the image forming apparatus shown in FIG.

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.

[Explanation of symbols]

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

Claims (1)

[Claims] 1. An aperture electrode body having a plurality of apertures controls the passage of charged toner through the aperture plate, and an image is formed on a support located on the opposite side of the toner supply source from the aperture electrode body. In the image forming apparatus, the insulating sheet provided on the side of the aperture electrode body facing the toner supply source and the side of the aperture electrode body facing the support body separately for each aperture. Control electrode, a toner carrier that forms a part of the toner supply source, is disposed so as to be in contact with the insulating sheet, carries the toner, and conveys the toner, the toner carrier and the control electrode An image forming apparatus comprising: a means for forming an electric field according to an image signal between the two.