JPH04355166A - Image forming apparatus - Google Patents

Abstract

PURPOSE:To enhance accuracy, in the title apparatus wherein a toner carrier and a rear electrode are arranged in opposed relationship so as to hold a control grid therebetween, by constituting the control grid by bonding and arranging a pair of wiring patterns composed of a large number of loop electrodes to both surfaces through insulating resin layers with a specific permittivity to cover the same with a non-thermosetting liquid insulating material. CONSTITUTION:Liquefied polyimide H with a permittivity epsilon of 4 or less is applied to a Cu thin plate 53a' in thickness of 20-30mum and a Cu thin plate 53b' is superposed on the Cu thin plate 53a' to form a sandwich structure which is, in turn, subjected to condensation reaction under heating to form a Cu bond. Next, a Cu thin plate 53' is subjected to etching treatment to form upper and lower loop electrodes 53a, 53b. Subsequently, the loop electrodes 53a, 53b are coated with a cover coat material 57 composed of polyimide of the same kind by screen printing. Then, the whole is heated and cured in a hot air type box- shaped oven to obtain a control grid.

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 are disposed facing each other with a control grid in which a group of openable and closable toner passage holes arranged in a predetermined direction interposed therebetween.

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. 5. The toner carrier 1 includes a sleeve-shaped developing roller that electromagnetically holds toner in a thin film, and the toner carrier 1. A matrix-like control grid 3 is disposed between the back electrode 2 and the back electrode 2 disposed opposite to the control grid 1, and the control grid 3 is energized in the X-Y axis direction.
The developing electric field acting on the toner passage hole 3a between the matrices is configured to be selectively cut off or conductive in accordance with image information, thereby causing the control grid 3 to appear on the recording paper 4 disposed on the surface of the back electrode 2. As shown in FIG. 6, each pair of loops is configured to allow the transfer of toner corresponding to image information through the toner passage hole 3a in the control grid. A matrix-like group of conducting wires consisting of a plurality of X-axis lines X1-X2... formed in a shape, and a pair of loop-shaped Y-axis lines Ya1-Ya2... each narrowly extending parallel to the X-axis line and inclined at a predetermined angle with respect to the axis. The toner passage hole 3a is formed at a portion sandwiched between the Y-axis line Ya1-Ya2 and the X-axis line X1-X2 for each pair.

[0004]The control grid 3 sequentially energizes the X1 to X2 lines 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 made into one pattern as a result. form a row,
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]

[Problems to be Solved by the Invention] In the above device, a method of manufacturing a control grid by arranging and fixing wire lines in a matrix is being considered, but when wire lines are used, the matrix spacing, tension etc. are likely to vary, and it is quite difficult to maintain good insulation at the intersections. For this reason, manufacturing using FPC has conventionally been considered in order to improve the precision of the matrix-like axis spacing, the homogeneity of tension, and the insulation properties.

However, even if FPC is used, the following problems still occur. First, to explain the manufacturing method of FPC, as shown in FIG. 4, FPC is made by applying a Cu thin film 43' on a thin base material 41 made of polyimide or polyester via an adhesive layer 42 using a roller or the like (not shown). a first adhesion step (a) of press-bonding; an etching step (b) of etching the Cu thin film 43' to form a predetermined wiring pattern 43;
It is formed by a second adhesion step (c) of overcoating polyimide 45 on the u thin film 43 via an adhesive layer 44.

However, if the above configuration is adopted, for example, Y
A thin layer base material 41 is provided between the upper loop electrode 43a extending in the axial direction and the lower loop electrode 43b extending in the Χ-axis direction.
Since the pair of adhesive layers 42a and 42b are interposed therebetween, the thickness is inevitably increased (60 to 70 μm).

On the other hand, it is necessary to apply a control voltage to each of the loop electrodes 43a and 43b in order to open and close the toner passage hole 3a. In order to maintain the distance between the control grid 3 and the developing roller 1, it is necessary to make a difference in the voltage applied to each loop electrode 43a, 43b in proportion to the distance between the control grid 3 and the developing roller 1, as shown in FIG. Since the gap is an extremely thin layer of around 0.2 mm, when the gap between the loop electrodes becomes thick, the voltage difference between the loop electrodes 43a and 43b becomes so large that it cannot be ignored. A reverse electric field is generated between the loop electrodes 43a and 43b, and this reverse electric field acts in a direction to prevent toner from passing through, or has an adverse effect on other adjacent passage holes.

[0009] In order to eliminate such drawbacks, the base material 4
1 and the adhesive layer 42 are being considered to be thinner,
If the base material 41 is made thin, the toner passage hole 3a and the loop electrodes 43a, 43b will be distorted or deformed due to heat shrinkage of the adhesive layer 42, etc. performed during the adhesion process, making it impossible to form the control grid 3 with high precision.

[0010]Also, epoxy adhesive is generally used in the FPC, but epoxy resin has a higher dielectric constant than other resins such as polyimide, so applying the control voltage will separate the epoxy resin from the adhesive. Charges may be accumulated in the adhesive layer 42, resulting in toner adhesion or the opening and closing of the toner passage holes not being able to be controlled smoothly.

In view of the drawbacks of the prior art, the present invention provides an image forming apparatus capable of generating printed dots with high precision and high resolution by reducing the thickness of the control grid and solving various problems caused by the thinning. The purpose is to provide.

0012

[Means for Solving the Problems] In order to achieve the above technical problems, the present invention provides a wiring pattern (hereinafter referred to as upper loop electrode) consisting of a large number of loop wires extending in the Y-axis direction. One wiring pattern consisting of multiple loop wires extending in the Χ-axis direction (hereinafter referred to as the lower loop electrode; the angle of change between the Y-axis and the Χ-axis is not 90°) is connected to each other via an adhesive layer. The first feature is that it is not fixed to the base material, but is directly bonded to the base material without using an adhesive layer.

The second feature is that the base material includes:
A single insulating resin body with a dielectric constant ε4 or less, more preferably 20
The point is that it is formed using an insulating resin material having a wall thickness of ~30 μm. In addition to polyimide, polyethylene, fluororesin, etc. can also be used for such an insulating resin material.

Now, it is necessary to insulate the upper surface of each of the wiring patterns without exposing them, but in this case, a non-thermosetting liquefied insulating material such as an ultraviolet curing resin is used instead of using a thermosetting insulating film. The third feature is that the insulating film is coated by coating and curing.

[0015]

[Operation] According to this technical means, since both the upper and lower loop electrodes can be directly bonded to both sides of the base material without providing an adhesive layer, the thickness between the two loop electrodes can be easily reduced. As a result, even if the voltage difference between the two loop electrodes is reduced, a control voltage that allows the toner passage hole to be opened smoothly can be maintained, and as a result, the reverse electric field generated between the loop electrodes is reduced. It is possible to eliminate the possibility that the reverse electric field acts in a direction to prevent toner from passing through or adversely affects other adjacent passage holes.

Furthermore, as shown in FIG. 7, a material with a lower dielectric constant than epoxy resin is used for the base material, and since the above-mentioned reverse electric field is kept low, electric charges are generated in the base material. As a result, it is possible to prevent toner from adhering to the toner passage hole, and also to increase the opening/closing speed of the toner passage hole.

Furthermore, in the present invention, since the surface of the loop electrode is formed by applying and curing an insulating non-thermosetting liquefied material, the overall thickness can be reduced, and the developing voltage can be set lower accordingly. In addition to improving safety, since the liquefied material is a non-thermosetting material that can be cured by ultraviolet rays, there is no possibility of thermal shrinkage occurring when coating the loop electrode, resulting in a thin layer. Even if a base material of

In this case, if the base material is made too thin, corona discharge etc. will occur due to the potential difference between the two loop electrodes, which may cause problems in terms of durability and dielectric strength. be. Therefore, in the present invention, the wall thickness is also set in a range of 20 to 30 μm in order to suppress the generation of a reverse electric field and prevent the above-mentioned defects.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be explained 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. First, a method for manufacturing a control grid according to an embodiment of the present invention will be explained step by step based on FIG. First, a thin Cu thin plate 53
After coating liquefied polyimide 51 on a' (a), Cu
By heating the thin plates 53b' with the liquefied polyimide 51 sandwiched between them in a sandwich structure, a dehydration condensation reaction occurs, and the chemical reaction results in Cu bonding. (b)

[0020] Incidentally, since such a method of performing Cu bonding without using an adhesive is already known, a detailed explanation thereof will be omitted, but the present invention is particularly concerned with the thickness of the polyimide. If it is made too thick, a reverse electric field will be generated which will hinder the passage of toner, and if it is made too thin, it will likely cause problems in terms of distortion and dielectric strength. Therefore, in the present invention, the thickness of the polyimide 51 after dehydration is adjusted to be approximately 25 μm. Further, the Cu thin plates 53a' and 53b' are set to have a thickness that allows etching treatment to be described later, specifically, about 18 μm.

Then, the thin Cu plate 53' is etched to form the upper loop electrode 53a and the lower loop electrode 53b. (c) Next, the loop electrode 53a,
The surface of 53b is coated, but in this case, if polyimide is overcoated through an adhesive layer as in the prior art, the thickness will inevitably become thicker, and electric charges will be accumulated in the adhesive layer, which is undesirable. Not only that, but it also becomes thicker. Therefore, it may be possible to apply and cure an insulating liquefied resin to directly coat the surface.

First, polyimide cover coat material 57 (trade name: SPI-100, manufactured by Nippon Steel Chemical Co., Ltd.), which is the same as the base material, was coated by screen printing, and then coated in a hot air box oven. , 130-25
Heat curing is performed by maintaining a temperature range of 0°C.

Then, a hole (φ0.25±0.1) is made by laser processing or the like at the intersection of the loop electrodes 53a and 53b of the FPC formed as described above (f).
, to check its dimensional accuracy, there are two points at positions approximately 100 mm apart in the Χ-axis direction and the Y-axis direction, respectively, with an arbitrary reference point as the center, and two points on the diagonal line of the reference point with the two points in between. When examining the dimensional error for one point, a total of three points, the dimensional error from the reference point to each point is 45 to 37.
5 μm (Χ axis direction), 0 to 126 μm (Y axis direction), 4
It was found that there was an error of '48'' (angular deviation), which is not a desirable value for forming high-resolution images.

Therefore, the material of the overcoat 55 is changed to an ultraviolet curable varnish, which is applied by screen printing in the same manner as described above, and then cured by irradiation with ultraviolet rays. Then, holes are made using the same processing method as described above at the intersections of the loop electrodes of the FPC formed as described above.
f), When examining the dimensional accuracy at the same three points as above, -20 to 17 μm (X axis direction), -21 to 3 μm (Y axis direction), 0'43" (angular deviation) It was confirmed that the error was significantly reduced compared to the above. It was also confirmed that the cross section of the control grid 3 had a smooth surface on the surface of the overcoat 55 without any unevenness. ( e)

Next, in order to confirm the effect of this example, when overcoating was performed in the same manner as above using a polyamide-imide material as the coating material, it was found that high dimensional accuracy was still maintained. confirmed.

Next, the effects of image forming apparatuses manufactured using the control grid manufactured according to the above embodiment and the control grid described in the prior art section were examined. FIG. 1 is a schematic diagram of the image forming apparatus having the above structure, in which 1 is a developing roller which supports a toner layer by the magnetic attraction force of an assembly of fixed magnets contained therein, and 2 is a developing roller configured such that a recording material 4 can be inserted into its surface. It is configured such that a developing voltage can be applied so that a developing electric field can be formed between the rear electrode and the developing roller 1.

The control grids 3A and 3B described above are arranged between the back electrode 2 and the developing roller 1. The spacing between the control grids 3A and 3B is such that, for example, the spacing between the developing roller 1 and the control grids 3A and 3B is 0.2±0.05, and the spacing between the control grids 3A and 3B and the back electrode 2 is 0.5±0.
Set it to be within the range of 2.

The conventional control grid 3B was formed by setting the base material 41 and coating material 45 to 25 μm each, the adhesive layers 42 and 44 to 20 μm each, and the Cu film to 18 μm. (Grid wall thickness 101 μm, gap between thin plates 65 μm) On the other hand, the control grid 3A of this embodiment is set to have a grid wall thickness of 111 μm and a gap between thin plates 53a/53b of 25 μm.

In this state, for example, when the loop electrode interval is 0.37 mm, the toner passage hole is φ0.25±0.1, and insulating toner in which a negative charge is injected is used, the developing roller 1 side An examination of the control voltage when using the control grid 3B of the prior art while setting the potential of the back electrode 2 to the ground potential and the potential of the back electrode 2 to +2000V shows that the toner passage hole 3a can be electromagnetically shielded. The shielding voltage is the upper/lower loop electrode 43a/4.
The control voltage of 3b was -400V/-800V. A clear dot pattern was formed when the open circuit voltage was -200/-50V, but if the potential difference was made smaller than this, the toner passage hole 3a would be clogged by the electric field, making it impossible to form desirable printed dots. Ta.

Next, when we examine the control voltage when using the control grid 3A of this embodiment, we find that the shielding voltage is
The control voltage of the lower loop electrodes 53a/53b is -400/
Although the voltage was -600V, which was the same as in the prior art, a clear dot pattern was formed even when the open circuit voltage was -200/-50V.

Next, by comparing the printed dots of the respective image forming apparatuses described above, it was confirmed that the dots of this embodiment had a larger dot diameter and higher resolution than the printed dots of the prior art.

Further, when a confirmation test was conducted for each of the above-mentioned devices for 500 hours at the above-mentioned control voltage, it was confirmed that the printed dots became thinner with time in the conventional image forming device, and therefore, the control grid 3A ,3B
Taking it out, the conventional technology has toner passage hole 3.
It was confirmed that there was a lot of toner adhering to surface a, causing some clogging, but in this example, almost no toner adhesion was observed, and the control grid 3A was charged from this surface. It was confirmed that there was no such thing.

Next, when the voltage applied to the back electrode 2 of this example was lowered to 1500 V and similar printing dots were formed, still good printing was confirmed. From this point of view, in this embodiment, the developing voltage can be lowered and safety can be improved.

Next, the corona discharge starting voltage (a phenomenon that does not cause dielectric breakdown but causes discontinuous discharge) between the loop electrodes was confirmed and found to be 465 V. It was confirmed that the shielding voltage of the electrodes 53a/53b was -600/-200V, which was lower than the corona discharge starting voltage, and had sufficient durability.

[0035]

[Effect] As described above, according to the present invention, an image forming apparatus is provided which is capable of reducing the thickness of the control grid, solving various problems caused by the thinning, and generating printed dots with high precision and high resolution. can be provided. It has various effects such as

[Brief explanation of the drawing]

FIG. 1 shows an operational diagram of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 shows a manufacturing procedure of a control grid according to an embodiment of the present invention.

FIG. 3 shows an operational diagram of an image forming apparatus according to the prior art.

FIG. 4 shows a manufacturing procedure of a control grid according to the prior art.

[Fig. 5] Overall configuration diagram showing the basic technology to which the present invention is applied

[Figure 6] Schematic diagram showing the arrangement of the Χ-Y axis loop lines of the control grid

[Figure 7] Dielectric properties of various resins (at1MHZ)

[Explanation of symbols]

1 Toner carriers 3A, 3B Control grid 3a Toner passage holes 43a/43b, 53a/53b Loop electrode 51
Insulating resin layer 55 Non-thermosetting liquefied insulation material

Claims (2)

[Claims] 1. An image forming apparatus in which a toner carrier and a back electrode are arranged facing each other across a control grid in which a group of toner passage holes that can be electromagnetically opened and closed are arranged, in which a large number of toner holes extending in parallel in a predetermined direction are provided. A pair of wiring patterns consisting of loop-shaped electrodes are directly connected to the front and back surfaces of the wiring patterns through an insulating resin layer having a dielectric constant of ε4 or less, and a non-thermosetting liquefied insulating material is applied to the upper surface of each wiring pattern. An image forming apparatus characterized in that the control grid is formed by coating and curing. 2. The thickness of the insulating resin layer is approximately 20 to 30 mm.
The image forming apparatus according to claim 1, wherein the image forming apparatus is set to μm.