JPH0858146A - Image formation device - Google Patents

Abstract

PURPOSE: To provide an entirely uniform stress to a toner layer by an aperture electrode element and thereby, provide the toner layer with an uniform thickness with a subsequent effect to prevent a concentration irregularity from being produced in an image formation device using the aperture electrode element which controls the flow of toner. CONSTITUTION: An aperture electrode element 3 is held in such a state that it slides over a toner carrier roller through a toner layer. In addition, holes or apertures 6a are formed in the same direction as an aperture 6, on the upstream side or downstream side of a toner transport direction of the aperture 6, on the sheet-like base 5 of the aperture electrode element 3. Since tension is given to the sheet-like base 5, a regular unevenness is formed on the upstream side and downstream side of holes or apertures 6a. This unevenness combs and loosens the toner layer to make its layer thickness even by the sliding action of the unevenness.

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 plotter, a facsimile and the like.

[0002]

2. Description of the Related Art Conventionally, as an image forming apparatus, 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 to generate an electric field. For example, the one that controls the toner particles to pass through the aperture and forms the image on the image forming medium by the toner particles that have passed is, for example,
It is disclosed in US Pat. No. 3,689,935.

This image forming apparatus includes a base material made of an insulating material, a continuous reference electrode formed on one surface of the base material, and a plurality of control electrodes formed on the other surface and insulated from each other. An aperture electrode body having at least one row of apertures penetrating the three electrodes for each of the control electrodes, and means for selectively applying a potential between the reference electrode and the control electrode, The means for supplying the charged toner particles so that the flow of the toner particles passing through the aperture is controlled by the applied potential, and the image forming medium and the aperture electrode body are relatively moved to move the image forming medium through the particle flow. And means for positioning in the road.

Also, for example, US Pat. No. 4,743,926.
No. 4,755,837, No. 4,780,733, and No. 4,847,796, an image using an aperture electrode body in which a control electrode is arranged on the image forming medium side and a reference electrode is arranged on the toner supply side so as to face each other. A forming apparatus is disclosed. Further, US Pat. No. 4,912,489 discloses an image forming apparatus using an aperture electrode body in which a reference electrode is arranged on the image forming medium side and a control electrode is arranged on the toner supply side so as to face each other.

[0005]

By the way, in the conventional image forming apparatus as described above, the aperture electrode body is placed at a position in contact with the means for supplying toner, for example, the toner carrying roller, through the toner layer. A device has been proposed that allows the aperture electrodes to be driven at a low voltage by arranging them. FIG. 6 shows an example of a conventional aperture electrode body. The aperture electrode body 31 is one in which apertures 61 are opened in a row at a predetermined pitch in a sheet-shaped base material 51 made of an insulating material, and control electrodes 71 made of copper foil are individually formed around the aperture 61. is there. Then, in the image forming apparatus, such an aperture electrode body is arranged so as to contact and slide on the toner layer carried on the toner carrying roller, and gives a mechanical stress to the toner layer, so that the toner is The toner is easily separated from the toner carrying roller so that the flow of toner passing through the aperture can be smoothly controlled. However, in such a configuration, since the aperture electrode body and the toner layer are in surface contact with each other, the stress applied to the toner layer is likely to be non-uniform overall, which causes unevenness in image density. It was

The present invention has been made in order to solve the above problems, and is an apparatus using an aperture electrode body arranged so as to be in contact with and slid on a toner layer, in which the aperture electrode body is a toner. It is an object of the present invention to provide an image forming apparatus which can make the stress applied to the layers uniform as a whole, and thus can make the toner layer thickness uniform, and which does not cause uneven density.

[0007]

To achieve the above object, an image forming apparatus according to a first aspect of the present invention has a toner supply unit for supplying toner and a plurality of apertures, and the toner is supplied from the toner supply unit and passes through the aperture. In the image forming apparatus for forming an image on the image forming medium by the toner that has passed through the aperture electrode body, the aperture electrode body is a sheet-like base material and this sheet. The base material is composed of apertures arranged in a row in a direction orthogonal to the toner transport direction, and control electrodes arranged on the periphery of the apertures. The sheet-shaped base material is held in a slidable state with tension, and is aligned in the same direction as the aperture on the upstream side or the downstream side of the aperture in the toner conveying direction. It is provided with a plurality of holes or openings. According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, a counter electrode is arranged so as to face the aperture electrode body with the image forming medium interposed therebetween.
An image forming apparatus according to a third aspect is the image forming apparatus according to the first or second aspect, in which the holes or holes are provided at the same pitch as the apertures or at a pitch that is a whole number. Is.

[0008]

According to the image forming apparatus of the present invention having the above-described structure, the aperture electrode body having the apertures arranged side by side in a line in the direction orthogonal to the toner transport direction is provided with the toner layer through the toner layer. The sheet-shaped substrate of the aperture electrode body is provided with a plurality of holes or holes arranged in the same direction as the aperture on the upstream side or the downstream side in the toner transport direction of the aperture, while being held slidably by the supply means. Since tension is applied to the sheet-shaped base material, relatively regular irregularities are formed on the upstream side and the downstream side of the hole or hole, and the irregularities slide on the toner layer, so that the toner layer is removed. Loosen and make layer thickness uniform.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An 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 this embodiment. The image forming apparatus 1 forms a toner image on an image forming medium 2 such as a recording sheet or an OHP sheet based on an image signal received from an external device (not shown). The toner supplying device 4 has an aperture electrode body 3 for controlling the flow of toner and a toner supply device 4 that carries the toner 12 and conveys it to the vicinity of the aperture electrode body 3 to supply the toner. The aperture electrode body 3 has a large number of apertures 6 arranged in a line in a direction orthogonal to the toner transport direction on a sheet-shaped substrate 5 made of an insulating material, and each aperture 6 is formed on the upper surface of the sheet-shaped substrate 5. A control electrode 7 is formed so as to individually and independently surround the periphery of 6, and the passage of toner is controlled by controlling the electric field in the aperture 6.

On the upper side of the aperture electrode body 3, a cylindrical rear electrode roller 8 (opposing electrode) is provided so as to face the aperture electrode body 3 with a gap of about 1 mm through which the image forming medium 2 passes. ) Is rotatably disposed on a chassis (not shown), and the image forming medium 2 is inserted into the gap.
Can be conveyed to the left in FIG. The aperture electrode body 3 and the back electrode roller 8 are arranged such that their longitudinal directions are orthogonal to the transport direction of the image forming medium 2. The toner supply device 4 is disposed below the aperture electrode body 3 along the longitudinal direction of the aperture electrode body 3. Furthermore, the back electrode roller 8
A fixing device 9 including a pair of pressure roller 9a and heat roller 9b is disposed at the destination of the image forming medium 2 conveyed by.

The details of each component will be described below.
The toner supply device 4 includes a toner case 11 that also serves as a housing of the entire device, a toner 12 as charged particles stored in the toner case 11, and a toner supply roller 1.
3, a toner carrier roller 14 that uniformly carries and carries the toner 12 toward the aperture electrode body 3, and the amount of the toner 12 carried by the toner carrier roller 14 is uniform on the surface of the roller 14. The toner layer regulating blade 15 is pressed against the roller 14 in order to regulate the above. The toner supply roller 13 supplies the toner 12 to the toner carrying roller 14. Both of these rollers 13 and 14 are rotatably supported by the toner case 11 in the direction of the arrow shown in the drawing, and are in a state of being close to each other. Are arranged in parallel with each other, and their rotation axes are arranged so as to be orthogonal to the transport direction of the image forming medium 2.

Further, the control electrode 7 and the toner carrying roller 14
In between, a control voltage application circuit 21 for applying a control voltage based on an image signal sent from an external device (not shown).
The control voltage application circuit 21 is configured to apply a voltage of 0 V or +50 V to the control electrode 7 based on the image signal. Further, a DC power supply 22 is connected between the back electrode roller 8 and the toner carrying roller 14, and this DC power supply 22 can apply a voltage of +1 kV to the back electrode roller 8. .

Next, the detailed structure of the aperture electrode body 3 will be described with reference to FIG. The aperture electrode body 3 includes a polyimide insulating substrate 5 having a thickness of 25 μm, a plurality of apertures 6 each having a diameter of about 60 μm formed in a row, and a control electrode 7 around each aperture 6. Is 8 μm thick
It is made of copper foil. This aperture electrode body 3
The base material 5 has a length substantially the same as the width (recording width) of the image forming medium 2, and the array pitch of the apertures 6 on the base material 5 is 125 μm in the case of 200 dpi, for example. If the width of the copper foil portion of each control electrode 7 provided around the aperture 6 is 20 μm, a space of 25 μm exists between the control electrodes 7 adjacent to each other. As shown in FIG. 1, the aperture electrode body 3 has the aperture 6 of the substrate 5 with the control electrode 7 facing the image forming medium 2 side.
It is provided so as to come into contact with the toner carrying roller 14 via the toner layer at the position of and to slide with the toner carrying roller 14.

Further, the aperture electrode body 3 is attached to the toner case 11 on the fixing member side in a state where tension is applied to the base material 5 in the direction orthogonal to the arrangement direction of the apertures 6, that is, in the toner conveying direction. A part of the aperture electrode body 3 is brought into pressure contact with the toner carrying roller 14.
Further, each control electrode 7 of the aperture electrode body 3 is provided with a conductive portion 7a for applying a voltage from the control voltage application circuit 21 in the downstream direction of toner conveyance. on the other hand,
The base material 5 of the aperture electrode body 3 is provided with a plurality of holes 6a in a row in a direction parallel to the arrangement direction of the apertures 6 on the upstream side of the toner transport of the apertures 6. The holes 6a may be provided at a uniform interval (aperture pitch) corresponding to each aperture 6 as shown in the figure, or may be provided by an integral multiple of the number of apertures 6. The operation of providing the hole 6a will be described later.

Further, the positional relationship between the aperture 6 of the aperture electrode body 3 and the toner carrying roller 14 will be described in detail. The center line of each aperture 6 is substantially the toner carrying roller 14.
The aperture electrode body 3 is arranged so as to pass through the uppermost portion of the peripheral surface of the aperture and the central axis thereof, and the distribution of the toner 12 passing through each aperture 6 is made uniform throughout the aperture.
Further, the wall surface 6b of the aperture 6 and the flying direction of the toner 12 are parallel to each other so that the toner can be stably flying. Further, the aperture electrode body 3 itself is brought into contact with the toner carrying roller 14 so as to bend left and right (in FIG. 1) about the aperture 6 by substantially the same angle, whereby the aperture electrode body 3 and the toner carrying roller 14 are brought into contact with each other. While making the contact area with the toner relatively large, the lower part of the aperture 6 is uniformly contacted with the toner carrying roller 14 in the left and right (in FIG. 1), thereby suppressing the occurrence of toner density unevenness. .

Next, the image forming operation of the image forming apparatus configured as described above will be described. By rotating the toner carrying roller 14 and the toner supplying roller 13 in the direction of the arrow shown in FIG. 1, the toner 12 sent from the toner supplying roller 13 is rubbed against the toner carrying roller 14 and is negatively charged, so that the toner is charged. It is carried on the carrying roller 14. The carried toner 12 is thinned by the toner layer regulating blade 15 and is charged,
The rotation of the toner carrying roller 14 causes the aperture electrode body 3 to rotate.
Be transported to. The toner 12 on the toner carrying roller 14 is rubbed by the base material 5 of the aperture electrode body 3 and supplied below the aperture 6.

Here, in accordance with an image signal sent from an external device (not shown), the control voltage applying circuit 21 applies a voltage of +50 V to the control electrode 7 corresponding to the image portion. As a result, a line of electric force directed from the control electrode 7 to the toner carrying roller 14 is formed near the aperture 6 corresponding to the image portion due to the potential difference between the control electrode 7 and the toner carrying roller 14. As a result, the negatively charged toner 12 receives electrostatic force in the direction of higher potential,
The toner is passed from the toner carrying roller 14 through the aperture 6 to the control electrode 7 side. This toner 12 pulled out
Is further caused by an electric field formed between the image forming medium 2 and the aperture electrode body 3 by the voltage of +1 kV applied to the back electrode roller 8 by the DC power source 22,
It flies toward the image forming medium 2 and deposits thereon to form pixels.

A voltage of 0V is applied from the control voltage application circuit 21 to the control electrode 7 corresponding to the non-image portion. As a result, an electric field is not formed between the toner carrying roller 14 and the control electrode 7, and the toner 12 on the toner carrying roller 14 does not receive the electrostatic force and therefore does not pass through the aperture 6.

In this embodiment, since the sheet-shaped base material 5 of the aperture electrode body 3 is provided with a tension in the toner transport direction, the direction (width) of the aperture electrode body 3 orthogonal to the toner transport direction. Direction), a contraction action occurs as a reaction force of the tension. However, since the holes 6a are provided at equal intervals in parallel to the arrangement direction of the apertures 6 corresponding to the apertures 6, the holes 6a are provided on the upstream side or the downstream side. On the side, a phenomenon occurs in which wrinkles or irregularities are regularly formed in the arrangement direction of the holes 6a. Therefore, when the pressure distribution in which the aperture electrode body 3 is in contact with the toner layer on the toner carrying roller 14 on the line AA ′ in FIG. 2 is examined, it is found that the pressure distribution regularly changes as shown in FIG. Therefore, the contact pressure applied to the toner layer becomes comb-shaped, and the toner layer can be loosened. As a result, it also contributes to making the toner layer thickness uniform, and it is possible to prevent uneven recording density.

In the above embodiment, the hole 6a is provided on the upstream side of the aperture 6 in the toner carrying direction, but it may be provided on the downstream side of the aperture 6 in the toner carrying direction. In this case, it is necessary to lay out so as not to interfere with the conductive portion 7a of the aperture electrode body 3. Further, although the hole 6a is shown as penetrating the base material 5 of the aperture electrode body 3, instead of penetrating the base material 5 as shown in the sectional view of FIG.
The recessed hole 6a may be provided on the side facing the toner carrying roller 14. Further, in the above-described embodiment, the control voltage of the aperture corresponding to the non-image portion is set to 0V, but this may be a negative voltage of, for example, −30V to −50V. You can get few images. Further, in the above, the back electrode roller 8
However, if the recording paper side has a potential relationship for attracting the charged toner, the back electrode roller 8 is not necessarily provided. When toner that is positively charged is used as the toner, the control electrode 7 and the back electrode roller 8 are used.
The voltage and the like applied to are set to the opposite potentials. Further, FIG. 5 shows still another embodiment of the aperture electrode body 3, in which the holes 6a provided in the sheet-shaped substrate 5 are provided at a pitch twice as large as the pitch at which the apertures 6 are provided.

[0021]

As described above, according to the image forming apparatus of the present invention, in the apparatus for forming an image using the aperture electrode body provided so as to come into contact with and slide on the toner layer supplied, By providing a plurality of holes or holes in the sheet-shaped base material of the electrode body on the upstream side or the downstream side of the aperture in the toner transport direction in the same direction as the aperture, the holes or the holes are relatively provided on the upstream side and the downstream side of the hole. Since regular irregularities are formed and these irregularities slide on the toner layer, the toner layer is loosened and the toner layer thickness is made uniform, so that uneven density of the image does not occur.

[Brief description of drawings]

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

FIG. 2 is a perspective view of an aperture electrode body.

FIG. 3 is a diagram for explaining the action of a hole provided in an aperture electrode body.

FIG. 4 is a side sectional view showing another embodiment of the aperture electrode body.

FIG. 5 is a perspective view showing still another embodiment of the aperture electrode body.

FIG. 6 is a perspective view of a conventional aperture electrode body.

[Explanation of symbols]

 2 image forming medium 3 aperture electrode body 4 toner supply device 5 sheet-like base material 6 aperture 6a hole 7 control electrode 8 back electrode roller (counter electrode) 12 toner 14 toner carrying roller

Claims (3)

[Claims] 1. An aperture electrode body comprising: a toner supply means for supplying toner; and an aperture electrode body having a plurality of apertures for controlling a flow of toner supplied from the toner supply means and passing through the aperture. In the image forming apparatus for forming an image on the image forming medium by the toner that has passed through the aperture electrode body, the aperture electrode body is arranged in a line in a direction orthogonal to the conveying direction of the toner on the sheet base material. A plurality of apertures arranged side by side and control electrodes arranged on the periphery of the apertures, the tension is maintained in a state of being slidable on the toner supply unit via the toner layer, and The sheet-shaped base material is provided with a plurality of holes or holes on the upstream side or the downstream side of the aperture in the toner transporting direction in the same direction as the aperture. . 2. The image forming apparatus according to claim 1, wherein a counter electrode is arranged so as to face the aperture electrode body with the image forming medium interposed therebetween. 3. The image forming apparatus according to claim 1, wherein the holes or holes are provided at a pitch that is the same as the pitch at which the apertures are provided or a pitch that is a fraction of an integer.