JPH04329157A - Image forming apparatus - Google Patents

Abstract

PURPOSE:To form a sharp image of high resolving power while preventing dot blurr by highly concentrating toner especially after the passage through a toner passing hole in an image forming apparatus wherein a toner carrier and a rear electrode permitting a recording material to move along the surface thereof are arranged in opposed relationship through a toner passing means wherein electromagnetically openable and closable toner passing hole groups are arranged in a predetermined direction. CONSTITUTION:A means 20 electromagnetically converging toner is arranged to the region opposed to each of the toner passing holes 3a on the side of a rear electrode as shown by a drawing and, as this converging means, various shapes such as a comb structure electrode, a grid electrode, a dot electrode or a ring hole electrode are considered.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an image forming apparatus configured to be capable of directly attaching a toner image to plain paper or other recording material without using a photoreceptor drum or other latent image carrier. The present invention relates to an image forming apparatus in which a toner carrier and a back electrode on the surface of which a recording material is movable are disposed facing each other through a toner passing means in which a group of openable and closable toner passing holes are arranged in a predetermined direction.

0002

[Prior Art] Conventionally, images are created in which toner carried on a toner carrier is directly transferred onto a recording material in a dot pattern corresponding to image information without using a photosensitive drum that functions as a latent image carrier. Forming devices are known. (Swedish Patent Application No. 8704883, etc.)

The configuration of such an apparatus will be briefly explained based on the basic configuration diagram shown in FIG. Back electrode 2 facing the body 1
A matrix-like control grid 3 is disposed between the two and the control grid 3 is controlled to be energized in the X-Y axis direction, so that the developing electric field acting on the toner passage holes 3a between the matrices corresponds to the image information. The toner passage hole 3a in the control grid 3 is configured to be selectively cut off or conductive, thereby allowing the toner passage hole 3a in the control grid 3 to be formed on the recording paper 4 disposed on the surface of the back electrode 2.
As shown in FIG. 9, the control grid 3 is configured to be able to transfer toner corresponding to image information through a plurality of loop-shaped control grids extending in the main scanning direction (X). The X-axis Xa of the book and each pair of loop-shaped Y extending narrowly in parallel and inclined at a predetermined angle with respect to the axis
It is formed by a matrix-like conducting wire group consisting of axes Ya2..., and the Y-axis Ya1-Ya2 and the X-axis X1 for each pair
- The portion sandwiched by X2 is formed to form the toner passage hole 3a.

[0004]The control grid 3 sequentially energizes the lines X1-X2 with a time difference in accordance with the insertion speed of the recording paper 4, so that the dot-shaped printing pattern 30 passing through the passage hole 3a is formed as a result. As a result, it is possible to form a dense dot pattern without making the width of the Y-axis loop line Ya1-Ya2, or in other words, the interval between the toner passage holes in the main scanning direction particularly dense. .

[0005]

[Problem to be Solved by the Invention] According to this basic technology, in order to achieve high resolution, in other words, to reduce the diameter of printed dots, it is possible to reduce the diameter of the toner passage hole of the control grid in accordance with this. Not only is clogging likely to occur, but it is also difficult to reduce the diameter of the passage hole due to processing problems. For this reason, in the device, the aperture of the toner passing hole is made larger than the diameter of the printed dot to some extent, and the opening and closing of the passing hole is controlled using a control voltage to electromagnetically narrow the toner passing hole while reducing the diameter of the printed dot. I was trying to However, in such a device, since the back electrode is formed in the shape of a plate, even if the toner passage hole is electromagnetically narrowed down as described above, the toner sucked from the toner carrier side by the so-called lens effect is temporarily absorbed into the toner passage hole. Although the toner is focused when passing through the toner, when it is emitted to the recording material side, the toner is spread out in a spreading shape by the plate-shaped back electrode and adheres to the recording material.As a result, the resolution is reduced due to the diffusion. Also, dot blurring occurs in which the peripheral edges of printed dots become thinner.

[0006] Furthermore, since the back electrode is plate-shaped as described above, even if an attempt is made to prevent leakage by covering the surface with an insulating material, leakage is likely to occur due to the effects of pinholes, etc. Moreover, since a high voltage of around 2000 V is applied to the back electrode, its dielectric strength also becomes a problem.

In view of the drawbacks of the prior art, it is an object of the present invention to provide a sharp and high-resolution image forming apparatus that enables highly focused toner after passing through a toner passage hole, thereby preventing dot blurring and the like. With the goal. Another object of the present invention is to provide an image forming apparatus having a back electrode that does not cause leakage or the like and is favorable in terms of dielectric strength.

[0008]

[Means for Solving the Problems] In order to achieve this technical problem, the present invention electromagnetically infuses toner into a portion facing each toner passage hole 3a on the back electrode side, as shown in FIG. A focusing means 20 is arranged, and such focusing means 20 can have various shapes such as a comb-structured electrode, a grid electrode, a dot electrode, a ring-hole electrode, etc.

[0009]

[Operation] The operation of the present invention will be explained based on FIG. First, while injecting a negative charge into the toner 5, the potential on the developing roller 1 side is set to the ground potential, and the potential on the back electrode 2 is set to +20
00V and, for example, the open circuit voltage of the control electrode 3 is set to -300V, the development electric field distribution curve G1 when the back electrode 2 is formed into a plate shape as in the conventional device is shown by an imaginary line. As shown, a distribution curve is formed in which the central part narrowed by the distribution line of the control electrode 3 is constricted in a C-shape, and as a result, the toner after passing through the toner passage hole 3a is spread out in a shape that spreads toward the end along the distribution curve. This results in the above-mentioned drawbacks.

On the other hand, according to the present invention, since the developing electric field is formed from one point (line) of the back electrode, the developing electric field distribution curve G2 is narrowed by the distribution line of the control electrode, as shown by the diagonal line. After that, the dots are further concentrated and formed on the printed dot side. Therefore, even if toner enters the toner passage hole 3a from the oblique side due to the lens effect of the control electrode 3, the toner after passing through the toner passage hole 3a will not be diffused and will be focused along the distribution curve G2, resulting in It is possible to form thick, high-resolution printing dots.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail by way of example with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, and relative positions of the components described in this example are not intended to limit the scope of this invention, but are merely illustrative examples. Not too much. Figure 2
1 shows a main configuration of an image forming apparatus according to an embodiment of the present invention. As described above, the control grid 3 includes a group of loop lines Χa extending in the direction of the Χ axis, a group of loop lines Ya extending to intersect the Χ axis at a predetermined angle, and a toner passage hole 3a drilled at the intersection. These are integrally formed using FPC, for example.

On the other hand, the toner passage hole 3 is located on the back electrode 2 side.
A large number of parallel electrode wires 21 and 22 are formed to connect the axes of a along the Χ-axis direction, and the electrode wires 21 and 22 are alternately connected every other wire on the right end side and the left end side, respectively. A back electrode is formed by forming a pair of comb-shaped electrodes 20A and 20B facing each other and integrally covering the electrodes 20A and 20B with an insulating material.

[0013] The toner is focused by applying the above-mentioned developing voltage to the comb-teeth electrodes 20A and 20B, but since the comb-teeth electrodes 20A and 20B are linear electrodes, The dots formed by A and 20B are oval dots extending in the Χ-axis direction.

In order to eliminate this drawback, as shown in FIG. 3, for example, below the pair of comb-like electrodes 20A and 20B extending in the Χ-axis direction, a structure similar to that described above is provided that extends in the Y-axis direction. A pair of comb-like electrodes 20C and 20D are disposed, and both electrodes are stacked vertically and arranged in parallel, and these are integrally covered with an insulating material to form a back electrode.

According to this configuration, both electrodes 20A to 20D
Since they are arranged so as to be able to intersect with each other on the axis of the toner passage hole 3a and are deflected at a predetermined angle in parallel planes, in other words, the +-shaped focusing means 20 is formed. The above drawbacks are eliminated.

[0016] Also, without using the above configuration, the structure shown in FIGS.
), the portions of the comb-teeth electrodes 20A and 20B that face the toner passage holes 3a may be formed into a small-diameter ring shape 20a or a small-diameter dot shape 20b. In this case, especially by forming the small diameter ring shape 20a, a fling effect can be produced, and a preferable printed dot with a thick peripheral edge can be formed.

Now, when the above-mentioned configuration is adopted, since the toner passage holes 3a are formed at very small intervals of about 0.1 to 0.6 mm, a uniform level voltage is applied to each of the adjacent parallel electrode lines. When a (DC voltage) is applied, the electric fields interfere with each other between adjacent electrodes 20 as shown in FIG. A portion of the toner may flow toward the adjacent electrode, resulting in blurred printing.

In order to eliminate this drawback, for example, as shown in FIG. 2, a switching means 25 capable of alternately supplying voltage to the comb-teeth electrodes disposed opposite to each other is used, and the pulse wave formed by the switching means 25 is It is preferable to configure the application timing to be different between adjacent electrode lines.

In this case, more accurate dot formation can be achieved by making the switching period correspond to the opening/closing period of the toner passage hole 3a of the control electrode. That is, since the X1-X2 .

In this case, the comb-teeth electrodes 20 to be switched are not necessarily limited to one pair, but are set at intervals of about 3 to 8 comb-teeth corresponding to the pulse period, and these comb-teeth electrodes 20 are switched by a rotary switch. By sequentially energizing the elements, it is possible to completely eliminate the possibility of interference from surrounding electric fields and further improve electric field concentration.

Now, the comb tooth 20 electrode is connected to the toner passage hole 3a.
Even if the portion facing the electrode is formed into a small-diameter ring shape or a small-diameter dot shape, since the electrode is a linear electrode after all, it is difficult to completely avoid toner scattering in the linear direction. Further, even if the electrode is formed into a small-diameter ring shape or a small-diameter dot shape, the diameters of these are both larger than the diameter of the linear electrode, and it is difficult to reduce the diameter.

FIG. 5 is an attempt to eliminate such drawbacks.
The configuration will be explained based on the manufacturing procedure. First, a wiring pattern 42 (for example, 18 μm in thickness) made of Cu or a metal vapor deposition film is formed on the back surface of an insulating thin layer 41 (for example, 35 μm in thickness) of polyimide or polyester, and then a φ0 .1~0
．． A 2 mm hole 40 is drilled until it reaches the wiring pattern 42. (a) After embedding solder in the laser-drilled portion, (b) the surface thereof is sequentially coated with an insulating film 43 and an antistatic layer 44. (c) According to this embodiment, since the point electrode 20c with a smaller diameter can be formed, the above-mentioned drawbacks can be overcome.

It should be noted that by using a needle-shaped sharpened electrode 20d as shown in FIG. 6 instead of using the above-mentioned point electrode, a strong electric field can be generated at the tip, and a strong electric field can be generated at the tip as shown in FIG. By using the cylindrical electrode 20e, a fling effect can be produced, and a preferable printed dot with a thick peripheral edge can be formed.

It is preferable that the lower surface side of the wiring pattern is hidden by an insulating base material 45. Also, the wiring pattern 4
Similarly to the comb-teeth electrode, 2 also has a toner passage hole 3a of the control electrode 3.
It is preferable to set a pulse wave period corresponding to the opening/closing period and to set the application timing between adjacent electrode lines to be different.

[0025]

As described above, according to the present invention, printed dots can be formed by further converging the toner after passing through the toner passage hole on the control electrode side. resolution images can be formed. Further, according to the present invention, since the back electrode can be formed as a dot or linear electrode, leakage etc. do not occur and it is preferable in terms of dielectric strength. It has various effects such as

[Brief explanation of drawings]

FIG. 1 shows a basic configuration diagram of the present invention.

FIG. 2 shows a main part configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 3 shows a modification of the back electrode shown in FIG. 2;

FIG. 4 is an operational diagram of the present invention according to claims 2 and 3.

FIG. 5 shows the manufacturing procedure of a back electrode according to another embodiment of the present invention and the configuration of its main parts.

FIG. 6 shows a main part configuration of a back electrode according to another embodiment of the present invention.

FIG. 7 shows a main part configuration of a back electrode according to another embodiment of the present invention.

[Fig. 8] Overall configuration diagram showing the basic technology to which the present invention is applied

[Figure 9] Schematic diagram showing the arrangement of the Χ-Y axis loop lines of the control grid

[Explanation of symbols]

1 Toner carrier 3 Control grid 3a Toner passage hole 20a...Back electrode 25 functioning as a focusing means Pulse applying means

Claims (6)

[Claims] 1. Via a toner passing means in which a group of toner passing holes that can be opened and closed electromagnetically are arranged along a predetermined direction,
A toner carrier carrying a toner layer and a back electrode on which a recording material can be moved are arranged facing each other, and the toner passing holes are selectively opened while applying a control voltage corresponding to image information to the toner passing means. In an image forming apparatus which is configured to be open and transfer the toner supported on the carrier to the recording material side through the passage hole, toner is electromagnetically applied to a portion facing each toner passage hole on the back electrode side. An image forming apparatus characterized by having a means for converging the [Claim 2]
Claim 1, wherein the focusing means is formed of a large number of parallel electrode wires connecting the axes of the toner passage holes, and uses pulse waves to vary the application timing between adjacent electrode wires. ). 3. The electrode functioning as the focusing means,
2. The image forming apparatus according to claim 1, wherein the pulse voltage is applied in correspondence with the opening/closing period of the toner passage hole of the control electrode. 4. The parallel electrode wires are stacked vertically and arranged in parallel, and both electrodes are arranged at a predetermined angle within a parallel plane so that they can intersect with each other on the axis of the toner passage hole. The image forming apparatus according to claim 1, characterized in that: 5. The image forming apparatus according to claim 1, wherein a portion of the back electrode facing the toner passage hole is formed in a small diameter ring shape or a small diameter dot shape. 6. The image forming apparatus according to claim 1, wherein the focusing means is a small-diameter ring hole-shaped or small-diameter dot-shaped electrode that protrudes above the wiring pattern.