JPH04101856A - Image formation equipment and method of image control - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" 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. In particular, a toner carrier having a toner layer on its surface and a back electrode are arranged with a control grid that forms toner holes corresponding to image information through power supply control, and a recording material is placed along the surface of the back electrode. The present invention relates to an image forming apparatus configured to be able to transfer toner that has passed through the toner passage hole onto a recording material while moving the toner.

"Prior Art" Conventionally, an image is 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. The forming device is well known (Sweden Patent Application No. 8704883, etc.), and the device configuration will be briefly explained based on the basic configuration diagram shown in FIG. sleeve-shaped toner carrier,
2 is a back electrode 2 disposed opposite to the toner carrier l;
A matrix-like control grid 3 is disposed between the two, and by controlling the power supply to the control grid 3 in the X-Y axis direction, the developing electric field acting on the toner holes 3a between the matrices is made to correspond to the image information. It is configured to be selectively cut off or conductive, and thereby the toner corresponding to the image information is transferred onto the recording paper 4 disposed on the surface of the back electrode 2 through the toner passage hole 3a in the control grid 3 on the toner carrier l. This makes it possible to transfer more information.

Further, the control grid 3 is arranged in the longitudinal direction (
A plurality of X axes 11X1. X2...
・and each pair of Y extending narrowly parallel to the current-carrying wire.
A matrix-like group of conductive wires consisting of shafts 1Yal, Ya2, . FP with a hole formed as a toner hole 3a
Formed by C.

The control grid is constructed by sequentially energizing the Xl, X2 lines, etc. with a time difference as shown in FIG. 6(b) in accordance with the insertion speed of the recording paper 4.

The dot-shaped toner pattern passing through the toner passage hole 3a is formed in a single row, and as a result, it is possible to form a dense dot pattern without making the Y-axis line width particularly dense.

``Technical Problems to be Solved by the Invention'' Now, the toner carrier used in the present apparatus or the conventional electrophotographic apparatus is generally composed of a developing roller made of a non-magnetic sleeve containing a magnet assembly, and the roller is In order to facilitate smooth image formation while regulating the toner layer carried on the surface to a uniform layer thickness using a doctor blade or the like, the toner layer forming surface of the roller is set to be larger than the maximum printable width. are doing.

Therefore, in the apparatus applied to the present invention (hereinafter referred to as the applied apparatus), a mesh-like control grid 3 disposed between the developing roller 1 and the back electrode 2 is provided as shown in FIG. 5(a). Although the width has been expanded to the non-printing area B located outside the maximum printable width, since no toner is transferred to the back electrode 2 side in the non-printing area B, the toner accumulation state continues. However, since the distance between the developing roller 1 and the back surface W1 pole 2 is very small, for example, during non-printing when no toner attracting electric field is applied to the back surface electrode 2 side, as shown in FIG. Toner falls from the toner layer 4 to the back electrode 2 side, and toner stains are likely to occur.

Furthermore, when the toner layer 4 deposited on the surface of the developing roller 1 becomes large, even if the toner passage hole 3a is electromagnetically shielded, the toner falls to the back electrode 2 side, causing toner stains.

In addition, when recording paper of different sizes is used, especially when moving to a larger size after continuous printing on a smaller size of recording paper, the developing roller l located outside the smaller size
The toner accumulated between the control grid 3 and the control grid 3 falls onto the back electrode 2 side during non-printing operations, which tends to cause image disturbance when printing starts again.

In view of the drawbacks of the prior art, it is an object of the present invention to provide an image forming apparatus that can prevent toner stains in non-printing areas and image disturbances immediately after transition from non-printing areas to printing areas. .

"Technical means for solving the problem" In order to achieve the technical problem, the present invention is provided in claim 5).
In the described invention, as shown in FIG. 1, at least during non-printing operation, a voltage having the same polarity as the charged charge of the toner layer 4 supported on the toner carrier l, in other words, the voltage applied to the back electrode 2 is applied. A voltage of opposite polarity is applied between the toner carrier 1 and the back electrode 2 during a non-printing operation, and the toner layer 4 located in this region is pushed back toward the toner carrier 1.

Of course, the non-printing area B may be a fixed non-printing area located outside the maximum recording paper width, or may be a variable printing area that changes based on the recording paper size in addition to the fixed cost printing area. May also include areas.

On the other hand, the invention set forth in claim 1 is to provide a device suitable for embodying the invention, which is characterized by being substantially the same as the mounting surface of the control grid 3 corresponding to the non-printing area B. A means 5 (3) for applying a voltage of opposite polarity to the voltage applied to the back electrode 2 is provided on the plane, and the voltage can be applied at least during non-printing operation.

That is, in this applied apparatus, the toner carrier 1 and the back electrode 2
Since there are minute gaps between the control grids 3, it is difficult to arrange the applying means so as to overlap the control grid 3, and the toner is more likely to be disturbed.

Therefore, the present invention provides a control grid 3 corresponding to the non-printing area B.
The above-mentioned drawbacks are solved by arranging the application means on substantially the same plane as the mounting surface of the device.

In this case, the applying means may be formed separately from the control grid 3; however, if configured in this way, the non-printing area B will be fixed, so it is preferable to form the applying means as a part of the control grid 3. It is preferable that the application means area of the control grid 3 is configured to be variable in accordance with the width of the recording paper inserted.

In addition, in the case where the application means 5 is formed as a part of the control grid 3, the voltage intensity of the opposite polarity is
If the voltage intensity is not set to be sufficient to electromagnetically close the toner through hole 3a, toner will fall to the back electrode 2 side through the toner through hole 3a, which is not preferable.

"Embodiments" Hereinafter, embodiments of the present invention will be described in detail by way of example based on 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.

FIG. 2 shows the configuration of main parts of an image forming apparatus according to an embodiment of the present invention. To briefly explain the configuration, ■ is a developing roller, 6 rotatably supports the developing roller 1, and A toner container having a strip opening 61 formed on the lower surface side, 30 a control grid unit stretched over the strip opening 61, 2 a back electrode disposed facing the control grid 30 with a predetermined gap in between, and 7 attached from the bottom surface. This is a device main body that positions and fixes the back electrode 2 at a predetermined position via a biased spring 71.

Next, to explain each of these members in detail, the toner container 6
A one-component magnetic toner is stored inside, and a doctor blade 62 is provided on the inner wall surface facing the developing roller 1. A thin knife-shaped spacer 23 is fixed on the bottom surface of the container on the incident side in the conveying direction of the recording paper 4, adjacent to the band-shaped opening 21, and covering almost the maximum width of the recording paper 4. 23 controls the guide of the recording paper 4.

The developing roller 1 consists of a developing sleeve 1a and a fixed magnet assembly 1b enclosed within the sleeve. , the developing sleeve 1@- is grounded.

As shown in FIG. 3, the control grid unit 3 includes a control grid main body 3 in which toner holes are arranged in a matrix.
A flat dummy electrode 31 (3
1a and 31b), and are connected to the energization control circuit 34 via a lead wire 32 and a drive circuit 33, respectively.

That is, the control grid main body 3A includes a plurality of X-axis closed loop lines extending in the longitudinal direction corresponding to the maximum width of the recording paper, and each pair of Y-axis closed loop lines extending narrowly parallel to the current-carrying lines. The toner through-holes 3a are arranged in a matrix at the intersections of the axial closed loop lines.

On the other hand, the dummy electrode 31 is arranged so as to surround the grid main body, and the electrode part 31a located in the longitudinal direction is
Band-shaped openings are formed at width intervals corresponding to the toner layer forming area of the developing roller located outside the maximum width of the recording paper, and at width intervals that match the width of the grid main body 3A in the electrode portion 31b located in the width direction. The width is set to be the same as 61 width.

Now, in such a device, the charge of the toner is changed to a negative charge,
The potential on the side of the developing roller 1 is set to the ground potential, the potential of the back electrode 2 is set to +2000 V, and the control voltage of the control grid main body 3A is set to the toner passage hole 3a shielding voltage of -500 V.

Further, when the open circuit voltage is set to -300V, the above-described effects of the present invention can be smoothly achieved by applying -50V corresponding to the shielding voltage to the dummy electrode 31 during printing operation as well as during non-printing operation. .

Incidentally, in this embodiment, since the dummy electrode 31 is formed in a flat plate shape without having the toner through hole 3a, it is necessary to have the voltage strength to push back the toner carried and deposited on the surface of the developing roller. The effect of the present invention can be achieved to some extent without being limited to the above-mentioned voltage intensity, as long as the voltage is of opposite polarity to the potential of the back electrode.

Furthermore, in the embodiment described above, since the dummy electrode 31 and the control grid main body 3A are formed separately, it is not preferable to apply a device in which the non-printing area is variable according to the size of the recording paper.

In this case, as shown in FIG. 4, a control grid 3B having a length corresponding to the toner layer forming area in the axial direction of the developing roller and the same width as the width of the band-shaped opening 61 is formed, and the control circuit 34
The above-described effects of the present invention can be achieved by applying current to the grid area 3B1 located outside the maximum width of the recording paper to a voltage of -800 V corresponding to the shielding voltage both during printing operation and during non-printing operation. This will be achieved smoothly.

"Effects" As described above, according to the present invention, even during non-printing operation, voltage is applied in the direction of pushing back the toner accumulated on the toner carrier, so that toner stains in the non-printing area and non-printing It is possible to prevent image disturbance immediately after transition from the area to the print area, and its practical effect is extremely high.

It has various effects such as

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram of the present invention, and FIG. 5 is an action diagram showing problems of the basic invention. FIG. 2 is a block diagram of main parts of an image forming apparatus to which the present invention is applied, and FIGS. 3 and 4 show a control grid unit incorporated in the apparatus. FIG. 6 and FIG. 7 are a schematic configuration diagram showing the basic invention to which the present invention is applied, and an action diagram showing the energization control state thereof.

Claims (1)

[Claims] 1) In an image forming apparatus in which a toner carrier having a toner layer on its surface and a back electrode are disposed facing each other with a control grid having a matrix of toner holes in between, the image forming apparatus corresponds to a non-printing area. An image characterized in that a means for applying a voltage of opposite polarity to the voltage applied to the back electrode is provided on substantially the same plane as the mounting surface of the control grid, and the voltage is configured such that the voltage can be applied at least during non-printing operation. 2) The image forming apparatus according to claim 1, wherein the voltage applying means is formed separately from the control grid. 3) The voltage applying means is formed as a part of the control grid, and the recording medium is inserted through the image forming apparatus. 4) The image forming apparatus according to claim 1, wherein the application means area of the control grid is configured to be variable according to the paper width. 5) Image forming apparatus according to claim 3), in which a toner carrier having a toner layer on its surface and a back electrode are disposed facing each other with a control grid having a matrix of toner holes therebetween, An image control method characterized by applying a voltage having the same polarity as the electrical charge of the toner carried on the toner carrier to a non-printing area between the toner carrier and the back electrode during printing operation.