JPH06246956A - Image forming apparatus - Google Patents

Abstract

PURPOSE:To provide an image forming apparatus that can form an image with high quality at high velocity. CONSTITUTION:The aperture electrode 1 of an image forming apparatus is of the type in which a plurality of apertures 6 having a diameter of 100mum is formed in a row on a polyimide insulation sheet 2 having a thickness of 25mum, and on the opening periphery of each aperture in the upper surface side of the insulation sheet 2, a control electrode 4 is formed with a thickness of 1mum. The control electrode 4 is formed only on the down stream side in the direction of movement of a toner carrier roller from the center of the apertures 6, and it is not disposed on the upper stream side thereof. Accordingly, toner carried on the toner carrier roller does not adhere to the surface at the side of the toner carrier roller of an aperture electrode 1, with result that a large amount of toner is supplied below the apertures 6 of the aperture electrode 1, so that an image with high density can be formed on the carrier.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a copying machine, a printer,
The present invention relates to an image forming apparatus that can be used for plotters, facsimiles, and the like.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus for obtaining an image on a support by controlling the passage of toner particles through an aperture by applying an image signal to an electrode having an aperture has been proposed in US Pat. No. 3,689,935. Has been done.

The image forming apparatus described in US Pat. No. 3,689,935 is composed of a shield electrode which is continuous on one side with a layer of an insulator interposed therebetween and a plurality of control electrodes which are insulated from each other on the other side. An aperture electrode body having at least one row of apertures penetrating three layers for each of the insulated control electrodes, and means for selectively applying a potential between the control electrode and the shield electrode. , A means for supplying the charged toner particles to the apertures of the aperture electrode body, a rear electrode of the support opposite to the aperture electrode body, to which a high voltage is applied, and the support relative to the aperture electrode body. And means for relatively moving the support to position it in the particle flow path.

Then, the charged toner particles are supplied from the toner supply means to the aperture of the aperture electrode body, and the aperture electrode body modulates the passage of the toner particles through the aperture. Then, the modulated toner particles are attracted toward the back electrode and adhere to the support conveyed on the back electrode to form an image.

Furthermore, the present applicants proceeded with the study and proposed an improved image recording apparatus in the application of Japanese Patent Application No. 4-254494. According to this, as shown in FIG.
The recording characteristics could be improved by disposing the carrier 31 holding the toner 30 and the recording electrode body 34 having the control electrode 33 disposed around the opening 32 in contact with each other.

[0006]

However, even in the image forming apparatus, the toner 30 conveyed by the movement of the carrier 31 in the direction of the arrow forms an electric field formed between the control electrode 33 and the carrier 31. As a result, the recording electrode body 34
The amount of the toner 30 that adheres to the surface of the carrier 31 and is supplied to the opening 32 decreases, and the resulting image becomes lighter to reduce the image quality, or the image is darkened. Then, there was a problem that the recording speed decreased.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to provide an image forming apparatus capable of forming a high quality image at a high speed.

[0008]

In order to achieve this object, an image forming apparatus of the present invention comprises a toner flow control means having a toner flow control part for controlling the passage of toner, and the toner flow control means has a toner flow control means. And a back electrode provided on the opposite side of the toner carrier to sandwich the toner flow controller, and the toner flow controller controls the passage of the toner supplied from the toner carrier. An image forming apparatus for forming an image on a support supported on a back electrode thereof, wherein the toner flow control section is provided with a control electrode for controlling passage of toner, The area of the control electrode on the downstream side is larger than that on the upstream side.

The toner carrier may be disposed in contact with the toner flow control means.

[0010]

According to the image forming apparatus of the present invention having the above structure, the toner carried by the toner carrier is supplied to the toner flow control unit without adhering to the toner flow control unit, and the toner flow control unit is operated. A large amount of the toner that has passed is deposited on the support after flying toward the back electrode, and an image is formed on the support.

[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 according to the present invention, in which a columnar cylinder serving as a back electrode having a gap of 1 mm on the upper side of an aperture electrode body 1 serving as a toner flow control means. The rear electrode roller 22 is a body (not shown)
It is rotatably disposed in the space and is configured to be able to convey the support body 20 inserted into the gap.

Further, below the aperture electrode body 1,
A toner supply device 10 is arranged along the longitudinal direction of the aperture electrode body 1, and the support body 20 is provided on the carry-in side of the aperture electrode body 1 with the aperture electrode body 1 and the back electrode roller 22. Transport roller 29 for transporting between
Is rotatably disposed, and further the back electrode roller 2
A fixing device 26 is provided at the destination of the support 20 conveyed by the sheet 2.

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
The toner 4 can carry the toner 16 on the outer peripheral portion thereof and can convey the toner 16 toward the aperture electrode body 1 by rotating clockwise in FIG.

Further, the supply roller 12 can supply the toner 16 to the toner carrying roller 14 by rotating in the clockwise direction in FIG. 1, and both are arranged in contact with each other. 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. It is pressed against the roller 14.

As shown in FIG. 2, the aperture electrode body 1 has a diameter of 10 μm on a 25 μm thick insulating sheet 2 made of polyimide.
The aperture 6 as a plurality of toner flow control units of 0 μm is set to 1
A control electrode 4 is formed in a thickness of 1 μm on the periphery of the opening of each aperture 6 on the upper surface side of the insulating sheet 2 (on the side opposite to the toner carrying roller 14) formed in rows. Then, in the aperture electrode body 1, the control electrode 4 is opposed to the support body 20 side as shown in FIG.
Are arranged so as to contact the toner on the toner carrying roller at the aperture position. Further, the control electrode 4 has a structure shown in FIG.
As shown in FIG. 5, it is formed only on the downstream side in the moving direction of the toner carrying roller 14 from the center of the aperture 6, and is not arranged on the upstream side.

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 supply 24 is connected between the back electrode roller 22 and the toner carrying roller 14, and this DC power supply can apply a voltage of +1 kV to the back electrode roller 22. It is like this.

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. 1, the toner 16 sent from the supply roller 12 is rubbed against the toner carrying roller 14 and negatively charged. The toner is carried on the toner carrying roller 14. The carried toner 16 is thinned by the layer regulating blade 18 and further charged, and then is conveyed toward the aperture electrode body 1 by the rotation of the toner carrying roller 14. And
The toner on the toner carrying roller 14 is the same as the aperture electrode body 1.
It is supplied under the aperture 6 while being rubbed by the insulating sheet 2.

At this time, since the control electrode 4 is not arranged on the upstream side in the moving direction of the toner carrying roller 14, the toner 16 carried on the toner carrying roller 14 is different from the conventional one, so that the toner 16 is carried on the aperture electrode body 1. A large amount of toner is supplied below the aperture 6 of the aperture electrode body 1 without adhering to the surface of the toner carrying roller 14 side.

On the other hand, the supporting body 20 is conveyed by the conveying roller 29 between the aperture electrode body 1 and the back electrode roller 22.

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, near the aperture 6 corresponding to the image portion, an electric force line from the control electrode 4 toward the toner carrying roller 14 is formed due to the potential difference between the control electrode 4 and the toner carrying roller 14. As a result, the negatively charged toner is subjected to an electrostatic force in the direction of higher potential, and the toner from the toner carrying roller 14 is moved to the aperture 6 side.
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.

At this time, since a large amount of toner 16 is supplied below the aperture 6 of the aperture electrode body 1, the support 20
An image with high density is formed in the image, and the image quality is improved.

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, between the toner carrying roller 14 and the control electrode 4,
Since the electric field is not formed, the toner carrying roller 14
The upper toner 16 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.

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.

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 electrode 4 is
Although it is formed only on the downstream side of the center of the aperture 6 in the moving direction of the toner carrying roller 14, as shown in FIG.
It does not matter even if the control electrode 4 having a size that does not adhere is disposed on the upstream side.

Further, 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.

[0031]

As is apparent from the above description, according to the image forming apparatus of the present invention, the toner flow control section of the toner flow control means is provided with the control electrode for controlling the passage of the toner, and the toner carrier is carried. Since the area of the control electrode on the downstream side in the moving direction of the body is made larger than that on the upstream side, it is possible to provide an image forming apparatus capable of forming a high quality image at a high speed.

[Brief description of drawings]

FIG. 1 is a sectional view 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 an enlarged view showing the vicinity of an aperture of an aperture electrode body.

FIG. 4 is a diagram showing another embodiment.

FIG. 5 is a diagram showing a conventional example.

[Explanation of symbols]

 1 Aperture electrode body 2 Insulating sheet 4 Control electrode 6 Aperture 14 Toner carrying roller

Claims (2)

[Claims] 1. A toner flow control unit having a toner flow control unit for controlling passage of toner, a toner carrier for supplying toner to the toner flow control unit, and the toner carrier sandwiching the toner flow control unit. And an image forming apparatus for forming an image on the support supported on the back electrode by controlling the passage of the toner supplied from the toner support by the toner flow control means. In the toner flow control section, a control electrode for controlling passage of toner is provided, and the area of the control electrode on the downstream side in the moving direction of the toner carrier is larger than that on the upstream side. Image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the toner carrier is arranged in contact with a toner flow control unit.