JPH0437871A - Image forming device - Google Patents

Abstract

PURPOSE:To suppress spread of electric field from an electrode and to faithfully stick developer corresponding to area of the electrode to a recording medium electrostatically by making spacing between the recording medium and the recording electrode smaller than the sum of the width of the recording elements constituting the electrode and the spacing between the elements. CONSTITUTION:The recording sheet 5 of endless belt shape which is the record ing medium to form an image formed on it by having the toner 2 stuck to it is installed with one part of it brought close, in the vicinity of the recording electrode 1. The image formed on the sheet 5 is carried in a direction of an arrow B by rotation of a driving roll 6b, and when it is passed by an image display part 8, it is displayed on the outside. When, it is set so that the width (a) of the recording element 1b constituting the electrode 1 equals 0.1 mm, the distance (b) between the recording elements 1b equals 0.25 mm, and the spacing between the recording electrode 1 (upper surface of recording element 1b) and the recording sheet 5l, equals 0.3 mm, l1 <=a+b is fulfilled, and the toner 2 corresponding to the area of the electrode 1 can be faithfully stuck to the recording sheet 5 electrostatically, and a bright image is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an image forming apparatus that forms an image by electrostatically adhering a developer to a recording medium.

<Prior art> Various devices have been developed to form images according to image information, and some of these devices use conductive magnetic toner, which is a fine powder developer, to electrostatically transfer the toner to a recording medium. There is an image device that forms an image by attaching it to a surface.

For example, the method shown in Japanese Patent Publication No. 51-46707 has been proposed. As shown in FIG. 6, a non-magnetic cylinder 50
The conductive magnetic toner 51 on the outer periphery of the non-magnetic cylinder 50 is attached to the outer periphery of the cylinder 50 and conveyed by an alternating magnetic field of a rotating magnet 52 provided coaxially with the non-magnetic cylinder 50 . Then, the toner 51 is passed through recording electrodes 50a densely arranged along the axial direction on the outer circumferential surface of the non-magnetic cylinder 50, and the conductive layer 53b, When the power supply unit 5 is in physical contact with the recording medium 53 formed by laminating an insulating layer (or dielectric layer) 53a,
4 to apply voltage. At this time, the recording electrode 50a
By applying a voltage according to image information between the insulating layer 53a of the recording medium 53 and the conductive layer 53b of the recording medium 53, the toner 51 is attached to the insulating layer 53a of the recording medium 53 to form an image.

Further, as shown in FIG. 7, an image forming apparatus to which the above image forming method is applied is configured such that a rotating device built in the developing unit 56 is used for the recording medium 53 conveyed by the driving conveying roller 55a and the driven conveying roller 55b. The rotation of the magnet 52 transports the toner 51 onto the recording electrode 50a, and the recording controller 5
The signal voltage from 7 causes the toner 5 to adhere or not to form an image.

For example, the signal voltage from the recording control section 57 is +40V.
When the toner is applied, the toner 51 adheres to the recording medium 53, and at 070, the toner does not adhere, and this operation is repeated to form an image.

After the image is displayed in the image display area 58, the residual toner 51 adhering to the recording medium 53 is rubbed by a cleaning member 59 made of conductive carbon fiber 1 conductive resin, conductive rubber, etc. It falls onto the magnetic cylinder 50 and is conveyed again in preparation for the next recording.

<Problems to be Solved by the Invention> However, in the above configuration, if the distance d between the recording electrode 50a and the recording medium 53 is larger than the radius a of each recording element constituting the recording electrode 50a (d>a ), since the electric field distribution spreads radially from each recording element toward the recording medium 53, the toner 51 is applied to the recording medium 53 over an area larger than the area of the recording electrode 50a as a whole.
There was a risk that the image would become blurred due to the adhesion of

To solve this problem, in order to narrow down the electric field distributed radially from the recording electrode 50a, it is necessary to increase the magnetic flux density of the rotating magnet 52, or to synchronize the magnetic pole passing through the recording electrode 50a with the signal voltage. There are means to do so.

However, when increasing the magnetic flux density of the rotating magnet 52, the diameter of the rotating magnet 52 must be increased, which increases the motor load for rotating the rotating magnet 52, which may result in increased power consumption. There is.

Further, in order to synchronize the magnetic pole passing through the recording electrode 50a and the signal voltage, a corresponding control circuit and the like are required, which may increase costs.

An object of the present invention is to solve the above problems of the prior art, and to reduce the electric field by making the distance between the recording medium and the recording electrode less than or equal to the sum of the width of the recording element constituting the recording electrode and the interval between the recording elements. An object of the present invention is to provide an image forming apparatus in which the spread of distribution is suppressed.

<Means for Solving the Problems> A typical means for solving the problems of the prior art and applied to the embodiments described below is a plurality of recordings for applying voltage to the developer according to image information. a recording electrode consisting of an element, a driving means for applying a signal voltage corresponding to image information to the recording electrode, a recording medium to which the developer is attached to form an image, and the recording electrode and the recording medium. and a developer supply means for supplying developer between the recording medium and the recording electrode, and the distance between the front rudder recording medium and the recording electrode is less than or equal to the sum of the width of the front rudder recording element and the distance between the recording elements. have sequentially.

<Function> According to the above configuration, by setting the distance between the recording medium and the recording electrodes to be equal to or less than the sum of the width of the recording elements constituting the recording electrodes and the distance between the recording elements, the electric field distribution from the recording electrodes is reduced. The developer can be electrostatically adhered to the recording medium faithfully in an amount corresponding to the area of the recording electrode while suppressing the spread.

<Embodiment> An embodiment of an image forming apparatus to which the present invention is applied will be described below with reference to the drawings.

FIG. 1 is a cross-sectional explanatory diagram showing a schematic configuration of an image forming apparatus, FIG. 2 is a perspective explanatory diagram of a recording electrode, FIG. 3 is a partially enlarged cross-sectional diagram of a recording medium, and FIGS. 4 and 5 are a recording medium. - It is a schematic illustration explanatory drawing which shows the electric field distribution between recording electrodes.

First, the schematic structure of the image forming apparatus will be described with reference to FIGS. 1 to 3.

In FIG. 1, reference numeral 1 denotes a recording electrode for applying a voltage to the developer according to image information. This recording electrode 1 is arranged closely along the axial direction on a convex portion 3a on the outer peripheral surface of a non-magnetic cylinder 3, which is a development sub-supply means for supplying a conductive magnetic developer (hereinafter referred to as R-toner 1) 2. is attached to.

In the recording electrode 1, as shown in FIG. 2, a plurality of recording elements 1b provided in parallel in the width direction of the substrate 1a are connected to a driving element 1c, and the recording electrode 1 is provided on the convex portion 3a.
Among them, a conductor exposed portion 1d that contributes to recording is arranged. Further, a plurality of holes 1e are bored in the substrate 1a along the axial direction of the non-magnetic cylinder 3. These holes 1e allow the toner 2 conveyed on the outer periphery of the non-magnetic cylinder 3 to
It is configured to pass in the direction of arrow A and reach the exposed conductor portion 1d. Further, a flexible printed circuit board is used as the substrate 1a, and as the drive element 1c, for example, a VFD driver (MS G1 manufactured by Oki Electric Co., Ltd.) is used.
163) is used.

As shown in FIG. 1, a rotating magnet 4 that is rotationally driven by a drive motor (not shown) is coaxially attached to the non-magnetic cylinder 3. As shown in FIG. The toner 2 is attached to the outer circumferential surface of the non-magnetic cylinder 3 and conveyed by an alternating magnetic field formed by the rotating magnet 4.

In the vicinity of the recording electrode 1, an endless belt-shaped recording sheet 5, which is a recording medium on which toner 2 is attached to form an image, is arranged with a portion of the recording sheet 5 close to it. The recording sheet 5 is held between a tension roller 6a and a drive roller 6b which are arranged in a pair above and below. The drive roller 6b is rotationally driven by a drive motor (not shown) and conveys the recording sheet 5 in the direction of arrow B in FIG.

As shown in FIG. 3, the recording sheet 5 is made of a surface layer 5a made of a transparent material whose main component is butyral resin or urethane resin, a colored inorganic substance, and a binder (acrylic resin, plastic resin). A colored layer 5b, a conductive layer 5c deposited with aluminum or ITO (indium and tin oxide) to provide conductivity, and a base material 5d made of a plastic resin such as polyethylene terephthalate or polyethylene 2 polypropylene are polymerized. It is composed of

The surface layer 5a and the colored layer 5b are electrically insulated, and the colored layer 5b is made of titanium oxide (TiO□) to produce white as the base color of the screen.

An inorganic substance such as aluminum oxide (Al2O, ) is used.

Reference numeral 7 denotes a recording control section for applying a voltage corresponding to image information to the recording electrode l. This recording control section 7 is
A signal voltage corresponding to image information is applied to the conductive layer 5c of the recording sheet 5 to cause the toner 2 to adhere to the surface layer 5a to form an image.

8 is an image display section for externally displaying the image formed on the recording sheet 5, and 9 is a cleaning member attached to the back plate 10 of the main body of the apparatus via a support member 10a. This cleaning member 9 is composed of a cleaning member main body 9a and a soft and conductive brush 9b,
By rubbing the recording sheet 5 with the brush 9b at an appropriate angle and distance, the toner 2 adhering to the recording sheet 5 is scraped off onto the non-magnetic cylinder 3. The cleaning member 9 may include carbon fiber,
Materials used include soft plastics (polyethylene, polypropylene), urethane rubber, silicone, etc., which have S-electricity when combined.

Further, a non-magnetic member 11 and a magnet 12 for supporting the recording sheet 5 are disposed at a position facing the cleaning member 9 with the recording sheet 5 interposed therebetween.

The toner 2 attached to the outer circumference of the non-magnetic cylinder 3 by the rotating magnet 4 is conveyed onto the recording electrode 1 through the hole 1d of the substrate 1a. At this time, by applying a voltage to the recording electrode 1 according to the image information, the toner 2 can be attached to the recording sheet 5 to form an image. Note that the toner 2 that did not contribute to image formation on the recording electrode 1 falls from the convex portion 3a of the non-magnetic cylinder 3 and is deposited on the recording sheet 5.
It does not affect the image formed.

The image formed on the recording sheet 5 is transferred to the drive roller 6
By the rotation b, the recording sheet 5 is conveyed in the direction of arrow B in FIG. 1, and when it passes through the image display section 8, it is displayed on the outside. The recording sheet 5 that has passed through the image display section 8 is stripped of the attached toner 2 by the cleaning member 9, and the toner 2 falls onto the non-magnetic cylinder 3 and is conveyed again to the next page. Prepare for records.

Next, the structure between the recording sheet 5 and the recording electrode 1 will be explained in detail with reference to FIG.

In this embodiment, the width a-0 of the recording element 1b constituting the recording electrode 1 is 11 mm, and the distance ll between the recording elements lb is
The distance El between the recording electrode 1 (the upper surface of the recording element 1b) and the recording sheet 5 was set to 0.3 mm.

Due to the rotation of the rotating magnet 4, the toner 2 conveyed between the recording electrode 1 and the recording sheet 5 is attached to the recording sheet 5 by the magnetic field formed by the rotating magnet 4.
It depends on the electric field distribution from The toner 2 has an acrylic resin containing about 30% to 50% magnetite and about 2% to 10% carbon, and has a volume resistivity of 1X10'' to 1×10 − (0 cm).

Further, the recording sheet 5 has a volume resistance value of the combined surface layer 5a and colored layer 5b shown in FIG.
O” (Ωell).

Under the above configuration conditions, from the recording electrode 1 to the recording sheet 5
The electric field distribution formed radially with respect to the magnetic field will be explained with reference to FIGS. 4 and 5.

When the width of the recording element 1b is a■, the electric field distribution is aIIIl! from the recording element 1b. Experiments have shown that the spread of the electric field at a location where the temperature is off is approximately 2 am.

For example, the width a of recording element 1b = 0.2 wa, recording element 1
Distance between b - 0.2 m, recording element 1b and recording sheet 5
Interval between j! , When set to =0.5 wr,
As shown in FIG. 5, interference between electric fields from adjacent recording elements 1b becomes strong, and there is a possibility that the image becomes unclear.

On the other hand, the electric field distribution formed by the recording element 1b of the recording electrode 1 shown in FIG.
In the case of 0.25 degrees and i, -0.3 degrees, there is little interference due to electric fields from adjacent recording elements 1b, and a clear image can be obtained.

To illustrate the numerical values obtained as a result of experiments by changing the values of a, b, and L above, ■a-2kaku, b=1m i, +
-0.5wm, ■a=0.2mj, b=0.1mj! +
Similar results were obtained in the case of -0.2 wm, ■a = 0.5 m, b = 0.3 m, and l + = 0.8 wm.

From the above results, if each numerical value is set to satisfy d≦a+b, it is possible to reduce the interference caused by the electric field from the adjacent recording element 1b without being influenced by the strength of the magnetic field.

Therefore, the toner 2 corresponding to the area of the recording electrode 1 can be faithfully electrostatically adhered to the recording sheet 5, and a clear image can be formed.

Further, since control for applying a signal voltage synchronized with the magnetic poles of the rotating magnet 4 in order to narrow down the electric field from the recording electrode 1 is not necessary, image quality can be improved at low cost.

<Effects of the Invention> As described above, the present invention allows the distance between the recording medium and the recording electrode to be less than or equal to the sum of the width of the recording element constituting the recording electrode and the interval between the recording elements. The spread of the electric field distribution can be suppressed, and the developer corresponding to the area of the recording electrode can be faithfully electrostatically attached to the recording medium.

Therefore, image quality can be improved at low cost.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional explanatory diagram showing a schematic configuration of an image forming apparatus, FIG. 2 is a perspective explanatory diagram of a recording electrode, FIG. 3 is a partially enlarged cross-sectional diagram of a recording medium, and FIGS. 4 and 5 are a recording medium. - Schematic explanatory diagram showing electric field distribution between recording electrodes The explanatory diagram, FIGS. 6 and 7, are explanatory diagrams of a conventional example. a is the width of the recording element, b is the interval between the recording elements, 11. l,
is the distance between the recording electrode and the recording medium, l is the recording electrode, la is the substrate, 1b is the recording element, 1c is the drive element, 1d is the exposed conductor, 1e is the hole, 2 is the toner, 3 is the nonmagnetic cylinder, 3a 4 is a convex portion, 4 is a rotating magnet, 5 is a recording sheet, 5a is a surface layer, 5
b is a colored layer, 5c is a conductive layer, 5d is a base material, 6a is a tensilan roller, 6b is a drive roller, 7 is a recording control section, 8 is an image display section, 9 is a cleaning member, 9a is a cleaning member main body, 9b 10 is a brush, 10 is a support member, 11 is a non-magnetic member, and 12 is a magnet.

Claims (3)

[Claims] (1) A recording electrode consisting of a plurality of recording elements for applying a voltage to the developer according to image information, a driving means for applying a signal voltage according to the image information to the recording electrode, and the developer a recording medium for forming an image by adhering to the recording medium; and a developer supply means for supplying a developer between the recording electrode and the recording medium, the distance between the recording medium and the recording electrode being , an image forming apparatus characterized in that the width is less than or equal to the sum of the width of the recording element and the interval between the recording elements. (2) The image forming apparatus according to claim 1, wherein the recording medium has a surface transparent resin layer, a colored inorganic substance, and a conductive layer in this order. (3) The image forming apparatus according to claim 2, wherein the image formed on the recording medium is a display device that is used by displaying the image on a display section.