JPH09193442A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simply constituted and inexpensive image forming device. SOLUTION: An aperture electrode body 1 is provided with the toner feed upstream end part of a base 2 brought into contact with a toner carrying roller 14 under pressure with the cut face 18 forming an 80 deg. attack angle with the toner carrying roller 14. Therefore, of the total quantity of a toner 16 carried on the surface of the toner carrying roller 14 and transported, the excess quantity is returned by the cut face 18 of the aperture electrode body 1 and a constant quantity of the toner is conducted into a gap between the aperture electrode body 1 and the toner carrying roller 14. Thus the toner is carried in the form of a uniformly thin toner layer.

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 applied to a copying machine, a printer, a facsimile 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 an aperture) is used, and a voltage is applied to the electrode based on image data to charge the electrode. U.S. Pat. No. 3,689,311 discloses a system in which a body (hereinafter referred to as a toner) is controlled so that it can pass through the aperture, and an image is formed on a support by the toner particles that have passed.
No. 935 and the drawings.

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 in which at least one row of apertures is formed through each of the control electrodes, a means for selectively applying a potential between the reference electrode and the control electrode, and an applied potential By means of supplying charged toner so that the flow of toner passing through the aperture is modulated, and means for relatively moving the support and the aperture electrode body to position the support in the particle flow path. Has been done.

However, in this apparatus, the recording quality is likely to be deteriorated because the toner is clogged in the aperture, and the recording speed cannot be increased so much.

Therefore, the applicant further studied, and in JP-A-6-155798, the recording characteristics can be greatly improved by disposing the carrier holding the toner and the aperture electrode in contact with each other. An image recording device is proposed.

In this image forming apparatus, an aperture electrode body made of an insulating sheet in which a plurality of apertures are arranged in a row is arranged such that one side thereof faces the peripheral surface of the toner carrying roller, and the aperture electrode body is arranged. On the surface opposite to the toner carrying roller, that is, on the surface facing the recording medium, control electrodes for controlling the passage of the charged toner through the apertures are separately installed for each aperture, and further, with a predetermined polarity. The back electrode roller to which a voltage is applied is arranged so as to contact the back surface side of the recording medium, and the toner extracted from the aperture is caused to fly toward the surface of the recording medium by electrostatic force.

According to this image forming apparatus, since the electric field generated by the control electrode is formed between the control electrode and the inside of the aperture, and between the aperture and the toner carrying surface of the toner carrying roller facing the aperture, the carried toner is carried. Since the control electric field can be applied directly to the, the control efficiency is good, and a part of the supplied toner receives mechanical force due to the contact with the aperture electrode body, so that it is not exposed inside the aperture corresponding to the non-image area. Even if it enters, it can be controlled so as not to pass through the aperture by the electric field inside the aperture, so there is no fogging. Therefore, a high quality image can be easily obtained. Furthermore, since the toner carrying roller and the aperture electrode body face each other with the toner layer interposed therebetween, they can be arranged at a relatively short distance,
Even with a low control voltage, the flow of toner can be controlled appropriately. Therefore, excellent effects such as low cost and high reliability can be expected without the need for expensive control drive elements.

To obtain a uniform image in this process, the toner on the toner carrier supplied under the aperture needs to be uniform. For this reason, there is used one in which the toner on the toner carrying roller is made to pass through a metal layer regulating blade arranged so as to be pressed in the direction of the toner carrying roller to make the toner layer thickness uniform.

[0009]

However, in the above process, a blade for uniformizing the toner on the toner carrying roller is required, and the structure of the apparatus becomes complicated, and it is difficult to reduce the size and cost. there were.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an image forming apparatus which does not require a new member for layer regulation and which is simple in construction and inexpensive. I am trying.

[0011]

In order to achieve this object, an image forming apparatus according to claim 1 has a charged body flow control means for controlling an electric field of each opening and a charged body flow control means therefor. An image forming apparatus comprising a charged body carrying means for supplying a charged body charged to a flow control means, wherein the charged body supply upstream end of the charged body flow control means is a charged body on the charged body carrying means. It is characterized in that it is arranged so as to be in pressure contact with.

Therefore, the end portion of the charged body flow control means makes the layer thickness of the charged body on the charged body supporting means uniform.

An image forming apparatus according to a second aspect of the present invention is the image forming apparatus according to the first aspect, wherein a side surface of an end portion of the charged body flow control means which is pressed against the charged body carrying means and a charged body. The angle of attack with the supporting means is in the range of 70 to 90 degrees.

An image forming apparatus according to a third aspect of the present invention is the image forming apparatus according to the first or second aspect, in which the charged body is pressed against the charged body by a sheet member arranged on the side opposite to the charged body carrying means. It is characterized by that.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to the present embodiment. A toner supply device 10 is provided below the image forming device, and an upper portion of the toner supply device 10 is a charging device for controlling a toner flow. An aperture electrode body 1 as a body flow control means is provided. A back electrode, preferably a back electrode roller 22, is rotatably disposed above the aperture electrode body 1 with a space of about 1 mm.
Further, in the gap between the aperture electrode body 1 and the back electrode roller 22, the recording medium 20 is separated by the rotation of the back electrode roller 22 in the direction of the arrow D shown in FIG. 1 is conveyed in the direction of arrow C, and a thermal fixing device 26 including a pair of pressure rollers and heating rollers is arranged at the destination of the conveyance. The heat fixing device 26 can be replaced with any one of a heat fixing method and a pressure fixing method.

Next, the respective constituent elements will be described in detail. First, as shown in FIG. 1, the toner supply device 10 includes a toner case 1 which also serves as a housing of the entire device.
1 is provided, and a charged body, preferably an insulating toner 16 is stored in the toner case 11, and also serves as a charged body carrying means for carrying the toner 16 and carrying it toward the aperture electrode body 1. The cylindrical toner carrying roller 14 is provided rotatably in the arrow B direction shown in FIG. A cylindrical supply roller 12 that feeds the toner 16 contained in the toner case 11 to the toner carrying roller 14 is provided diagonally below and to the left of the toner carrying roller 14.
Are provided rotatably in the direction of arrow A shown in FIG. The supply roller 12 and the toner carrying roller 14 are arranged in parallel with each other such that the generatrix of their cylindrical surfaces is in contact with each other.

As shown in detail in FIG. 2, the aperture electrode body 1 is composed of, for example, an insulating base 2 made of polyimide having a thickness of about 25 μm.
In addition, a large number of apertures 6 having a diameter of about 60 μm are formed in a line in the longitudinal direction of the aperture electrode body 1. Around the aperture 6, a control electrode 4 having a thickness of about 8 μm and made of a conductive metal pattern such as copper or gold is formed for each aperture 6.

A lead wire 7 made of a conductive metal pattern is drawn from the control electrode 4 to one side of the aperture array and is connected to a drive IC 8 mounted on the base 2.

The base 2 on the other side of the aperture row is cut parallel to the aperture row at a distance of about 5 mm from the aperture row, and the cut surface 18 makes an angle of about 80 degrees with the base surface. In addition, the cut end is a polyimide sheet 17
And is overlaid and adhered to the upper surface of the base. The opposite side of the polyimide sheet 17 is adhered to the toner case.

The aperture electrode body 1 is a toner carrying roller 1
4, the center line of each aperture 6 passes through the uppermost part of the peripheral surface of the toner carrying roller 14 and the central axis of the toner carrying roller 14, the drive IC 8 side is the toner supply downstream side, and the polyimide sheet is 17 The adhesive side is arranged with the toner supply upstream side, and the base 2 of the aperture electrode body 1 is arranged.
Since the end of the IC mounting side and the end of the polyimide sheet 17 which is not adhered to the base are adhered to the toner case by applying tension, the base 2 bends about 3 times on both sides around the aperture row. And about 5mm on both sides of the aperture row
Is pressed against the toner carrying roller.

According to this, the respective apertures 6 are evenly arranged on the left and right with the uppermost portion of the peripheral surface of the toner carrying roller 14 as a reference, so that the distribution of the toner 16 passing through each aperture 6 can be adjusted. It can be made uniform in the whole area. Moreover, since the wall surface of the aperture 6 and the flying direction of the toner 16 are parallel to each other, it is possible to stably fly the toner.

The end of the base 2 of the aperture electrode body on the upstream side of the toner supply is pressed against the toner carrying roller 14, and the cutting surface 18 forms an attack angle of 80 degrees with the toner carrying roller 14.

Based on the image signal, the drive IC 8 supplies a positive voltage of about +30 V to the control electrode 4 corresponding to the image portion and 0 V to the control electrode 4 corresponding to the non-image portion, or , −30 V is applied. On the other hand, a backside voltage application circuit 24 composed of a DC high voltage power supply is connected between the backside electrode roller 22 and the toner carrying roller 14, and a high voltage of about +1 kV can be applied to the backside electrode roller 22. It is like this.

Next, the operation of the image forming apparatus configured as described above will be described.

First, when the supply roller 12 is rotated in the direction of arrow A shown in FIG. 1, the toner 16 contained in the toner case 11 is removed from the toner carrying roller 14.
Conveyed toward. Then, the excess toner 16 supplied from the supply roller 12 is returned by the cut surface 18 of the aperture electrode body 1, and a certain amount of toner is guided between the aperture electrode body 1 and the carrying roller to be thin. The toner is carried as a toner layer having a uniform thickness. The toner thinned on the toner carrying roller is guided between the toner carrying roller 14 and the aperture electrode, and is charged to a predetermined polarity, here negative polarity (minus), while being rubbed by the aperture electrode.

The toner 16 carried on the toner carrying roller 14 is held on the cylindrical roller surface of the toner carrying roller 14 as the toner carrying roller 14 rotates in the direction of arrow B, and the aperture electrode is held. It is conveyed toward the body 1.

Since the toner on the toner carrying roller 14 is rubbed against the aperture electrode body 1 and is rolling, the aperture of the aperture electrode body 1 is kept in a state where the adhesive force between the toner carrying roller 14 and the toner is sufficiently relaxed. The toner 16 supplied below 6 can control the passage of the aperture 6 with a low control voltage, and the flow of toner can be appropriately controlled according to the image signal.

For example, in response to an image signal, the control drive ICs 8 to +3 for the control electrode 4 corresponding to the image portion.
When a positive voltage of 0 V is applied, an electric force directed from the control electrode 4 to the toner carrying roller 14 near the aperture 6 corresponding to the control electrode 4 due to a potential difference between the control electrode 4 and the toner carrying roller 14. A line is formed. As a result, the negatively charged toner 16 receives an electrostatic force in the direction of higher potential, passes through the aperture 6 from above the toner carrying roller 14, and is drawn out to the control electrode 4 side. The extracted toner 16 is further applied to the recording medium 2 by a high voltage of +1 kV applied to the back electrode roller 22.
0 and the aperture electrode body 1 generate an electric field,
It flies toward the recording medium 20 and is deposited on the recording medium 20 to form dot-shaped pixels.

A negative voltage of 0V or -30V is applied from the driving IC 8 to the control electrode 4 corresponding to the non-image area. As a result, between the toner carrying roller 14 and the control electrode 4, the toner carrying roller 14
An electric field directed toward is not formed and cannot pass through the aperture 6. Moreover, at this time, when a negative voltage of -30 V is applied, a voltage lower than that of the toner carrying roller 14 is applied to the control electrode 4, so that an electric field corresponding to the image portion is generated between them. Therefore, the opposite electric field is formed, and the flying of the toner 16 is more effectively suppressed. Therefore, an image with less fog is formed.

On the other hand, the recording medium 20 conveyed through the gap between the aperture electrode body 1 and the back electrode roller 22 has the open aperture 6 of the open aperture 6 while one row of pixels is formed on the surface of the recording medium 20. One pixel is sent in the direction orthogonal to the row. Then, by repeating the above process, a toner image is formed on the entire surface of the recording medium 20. After that, the toner image formed on the recording medium 20 is fixed on the recording medium 20 by the heat fixing device 26.

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, the upstream end of the aperture electrode body 1 in the embodiment described above is adhered to a polyimide sheet and pressed against the toner carrying roller, but a metal plate or a ceramic plate may be used instead of the polyimide sheet. good.

The edge angle is not limited to 80 degrees.
However, when the angle of attack with the toner layer becomes small, the thickness of the toner layer becomes large and the stability of the layer thickness formed becomes low, so 70 to 90 degrees is preferable.

Particularly when the angle is 90 degrees, there is an effect that the manufacturing method of the base 2 is simplified.

Further, in the embodiment described above, the aperture electrode body 1 in which the circular apertures 6 are provided in a row is used as the charged body flow control means. Alternatively, a mesh-shaped electrode body as described in Japanese Patent Publication No. 1-503221 can be used.

[0037]

As is clear from the above description, according to the image forming apparatus of the first aspect, the aperture electrode body base regulates the toner layer, so that it is not necessary to separately provide a toner layer regulating member. There is an effect that a simple and inexpensive image forming apparatus can be provided.

Further, according to the image forming apparatus of the second aspect, it is possible to provide an image forming apparatus capable of forming a high-quality image without unevenness at low cost by obtaining a stable toner layer thickness. .

According to the image forming apparatus of the third aspect, there is an effect that the end portion of the base of the aperture electrode body can be pressed against the charged body layer with a simple structure.

[Brief description of the drawings]

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

FIG. 2 is a partially cutaway perspective view of an aperture electrode body as a charged body flow control means of the present invention when viewed from above.

FIG. 3 is an enlarged view of the vicinity of an aperture electrode body of an image forming apparatus embodying the present invention.

[Explanation of symbols]

 1 Aperture Electrode Body 2 Base 4 Control Electrode 6 Aperture 14 Toner Bearing Roller 16 Toner 17 Sheet 18 Cut Surface

Claims (3)

[Claims] 1. An image forming apparatus comprising: a charged body flow control means having a plurality of openings for controlling an electric field of each opening; and a charged body carrying means for supplying a charged charged body to the charged body flow control means. The image forming apparatus, wherein the charged body supply upstream side end portion of the charged body flow control means is arranged so as to be in pressure contact with the charged body on the charged body carrying means. 2. The angle of attack between the side surface of the end of the charged body flow control means that is pressed against the charged body carrying means and the charged body carrying means is in the range of 70 degrees to 90 degrees. The image forming apparatus according to claim 1. 3. The image forming apparatus according to claim 1, wherein the end portion is pressed against the charged body by a sheet member arranged on the opposite side of the charged body holding means.