JPH04366859A - Image forming device - Google Patents

Abstract

PURPOSE:To enhance the compressing efficiency of developer accumulated between a recording electrode and a recording medium. CONSTITUTION:By providing a regulating member 14 between the recording electrode 1 and a recording sheet 5, toner 2 carried on a sleeve 3 by rotating a rotary magnet 4 is intercepted and accumulated before a conductor exposure part 1d. The intercepted toner 2 is forcibly housed and compressed in a toner housing chamber constituted of the electrode 1, the sheet 5 and the regulating member 14. Besides, the concentration of the toner becomes large in comparison with a case that the regulating member 14 is not provided. Thus, the resistance value of the toner between the electrode 1 and the sheet 5 is lowered and the density of an image can be made dense.

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 that forms an image by electrostatically adhering a conductive magnetic developer to a recording medium.

0002

[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 adhere the toner to a recording medium. There are image forming devices such as printers and display devices that form images.

[0003] For example, this will be explained with reference to a display device shown in FIG. An endless recording medium 51 that is conveyed in the direction of arrow a is installed over the driving conveyance roller 50a and the driven conveyance roller 50b. A magnet roller 53a magnetized in the radial direction is rotatably provided in the developing device 52.
A sleeve 53b made of a non-magnetic material is provided concentrically around the . Recording electrodes 54 are densely arranged at equal intervals in the longitudinal direction on the circumferential surface of the sleeve 53b.
It faces the recording medium 53 with a small distance therebetween. The magnet roller 53a forms an alternating magnetic field, and by rotating it in the direction of arrow b, the conductive magnetic toner 55 is conveyed in the direction of arrow c. By applying a signal voltage according to the image information from the recording control section 56 between the recording electrode 54 and the conductive layer 51a while conveying the toner 55, the toner 55 is electrostatically attached to the insulating layer 51b. form an image.

For example, when the signal voltage from the recording control section 56 is +30V, the toner 55 adheres to the recording medium 51, and when the signal voltage is 0V, it does not adhere, and this operation is repeated to form an image.

After the image is displayed on the image display section 57, the toner 55 adhering to the recording medium 51 is rubbed by a cleaning member 58 made of conductive carbon fiber or the like and falls into the developing device 52. The image is then conveyed again and used for the next image formation.

FIG. 17 is an enlarged schematic explanatory diagram of the image forming portion of the display device. The recording electrode 54 is made of a flexible wiring member, and the sleeve 53
It is attached to the surface of b using double-sided tape or the like. A conductor exposed portion 54a is formed at the end of the recording electrode 54 at the position closest to the recording medium 51, and a through hole 54b corresponding to the toner 55 conveyance path is formed upstream from this in the toner conveyance direction. is perforated. This through hole 54b
The size is set so that the amount of toner flowing through the through hole 54b is greater than the amount of toner flowing out from between the recording medium 51 and the exposed conductor portion 54a.

Therefore, as the toner 55 is transported in the direction of arrow c, the toner 55 is dammed up in front of the exposed conductor portion 54a as shown in FIG. 17, and a pooled state of the toner 55 is formed. The pressure generated by this accumulated state of toner 55 is required to obtain appropriate image density.

[0008]

However, in the above-mentioned prior art, in order to constantly form a pooled state of toner 55 and obtain a desired image density, it is necessary to adjust the toner transport speed and the total gap between the recording medium and the recording electrode. Various constraints exist in relation to area. That is, in order to compress the toner 55 accumulated between the recording medium and the recording electrode, it is necessary to increase the toner conveying speed.
The motor that drives 3a generally needs to have a high output, which increases power consumption and may increase the size of the device.

[0009] In addition, in order to constantly form the accumulated state of the toner 55, the amount of gap between the recording medium and the recording electrode must be extremely narrow, and the driving conveyance roller 50 must be made extremely narrow.
In order to ensure the accuracy of the components of the roller a, the driven conveyance roller 50b, and the sleeve 53b, costs tend to increase.

An object of the present invention is to provide an image forming apparatus that solves the problems of the prior art described above.

[0011]

[Means for Solving the Problems] A typical means for solving the problems of the prior art described above and applied to the embodiments described below is to use a recording electrode for applying a voltage to a developer according to image information. , a relatively movable recording medium for depositing the developer to form an image, a developer supply means for supplying the developer between the recording electrode and the recording medium, and the recording electrode and the recording medium. It is characterized by comprising a compression means for compressing the developer accumulated between the recording medium and the recording medium.

0012

[Operation] According to the above structure, since the compression means for compressing the developer accumulated between the recording electrode and the recording medium is provided, the degree of compression of the developer can be improved. Thereby, the developer transport speed for obtaining the necessary compressive force of the developer can be reduced. In addition, if the developer transport speed is not changed, the volume resistance of the developer is lowered by increasing the compressive force, and the distance between the recording electrode and the recording medium is increased, allowing more developer to be accumulated. .

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image forming apparatus to which the present invention is applied will be described below with reference to the drawings. In this embodiment, a display device will be used as an image forming device.

FIG. 1 is a schematic cross-sectional view of an image recording section, FIG. 2 is a cross-sectional explanatory diagram showing a schematic configuration of an image forming apparatus, FIG. 3 is a perspective explanatory diagram of the image recording section, and FIG. 4 is a partially enlarged cross-sectional view of a recording medium. figure,
FIG. 5 is a schematic cross-sectional view when there is no toner dam in the image recording section, FIGS. 6 and 7 are schematic explanatory diagrams showing the principle of image recording, and FIG. 8 is a diagram showing the relationship between voltage applied to the recording sheet and time. Graph, FIG. 9 is an explanatory diagram showing before and after the toner is dammed in the image recording section, FIG. 10 is an enlarged explanatory diagram when the toner is dammed in the image recording section and a steady state is reached, and FIG. 11 is the pressure applied to the toner. 12 is a graph showing the relationship between toner compression force and toner volume resistance value, FIG. 13 is an explanatory diagram when the drive roller diameter and sleeve diameter are increased, and FIG. 14 is another example of the image recording section. FIG. 15 is a schematic cross-sectional view showing another example of the regulating member.

First, the general structure of the display device will be explained with reference to FIGS. 2 to 4. In FIG. 2, reference numeral 1 denotes a recording electrode for applying a voltage to a conductive magnetic developer (hereinafter referred to as "toner") 2 in accordance with image information. This recording electrode 1 is affixed along the axial direction onto the outer peripheral surface of a non-magnetic cylinder 3 (hereinafter referred to as "sleeve 3"), which is a developer supply means for supplying toner 2, with double-sided tape or the like. There is.

The recording electrode 1 has, as shown in FIG.
A flexible printed circuit board 1b whose surface is covered with an insulating cover film 1a is used. The conductor portion densely formed on the substrate 1b is connected to the drive element 1c provided on the upstream side, and the downstream end portion is provided with a conductor exposed portion 1d that contributes to recording without the cover film 1a. It is being Further, a plurality of through holes 1e are bored along the axial direction of the sleeve 3 at predetermined positions in the substrate 1b. The toner 2 conveyed in the direction of arrow a on the outer circumference of the sleeve 3 passes through these holes 1e.
It is configured to reach the conductor exposed portion 1c. Incidentally, as the drive element 1c, for example, a VFD driver (MSG1163 manufactured by Oki Electric) is used, and the conductor portion is formed of a copper etching pattern.

[0017] Here, the characteristics of the toner 2 used in this example will be explained. Volume resistance value: 103 to 109 Ω.
cm, particle size: average volume particle size 8 μm to 15 μm, composition: consisting of plastic resin such as acrylic, nylon, polyethylene, polypropylene, 1 to 10% (weight ratio) carbon, and 40 to 70% (weight ratio) ferrite. I used something.

As shown in FIG. 2, a rotating magnet 4 is mounted concentrically within the sleeve 3. As shown in FIG. The rotating magnet 4 is rotationally driven by a drive source (not shown), and is mounted concentrically around a rotating shaft 4a. As the rotating magnet 4, a cylindrical magnetic roller having a diameter of 40 mm and having 10 to 20 magnetic poles is used, and the maximum magnetic flux density directly above the magnet is 1000 Gauss.
s was used. The toner 2 is attached to the outer circumferential surface of the sleeve 3 and conveyed by a rotating 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 stretched between a driving roller 6a and a tension roller 6b which are arranged in a pair above and below. The drive roller 6a 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. 4, the recording sheet 5 has the following features:
A surface layer 5a made of a transparent material whose main component is butyral resin, a white layer 5b made of a white inorganic substance and a binder (acrylic resin, plastic resin), aluminum or ITO (indium) for conductivity. It is constructed by laminating a conductive layer 5c deposited with tin oxide) and a base material 5d made of a plastic resin such as polyethylene terephthalate, polyethylene, or polypropylene. The conductive layer 5c is covered with the surface layer 5a and the white layer 5b, and a conductive portion is formed at the end of the recording sheet 5 with a bias portion partially exposed. The characteristics of the recording sheet 5 are shown in the table below. (The following is a blank space) The surface layer 5a and the white layer 5b are electrically insulated, and the white layer 5b is made of titanium oxide (TiO2) and aluminum oxide (Al) in order to produce white as the base color of the screen.
Inorganic substances such as O3) are used.

Reference numeral 7 denotes a recording control section for applying a voltage to the recording electrode 1 according to image information. This recording control section 7 applies a signal voltage according to image information 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.

Reference numeral 8 represents an image display section for externally displaying the image formed on the recording sheet 5, and reference numeral 9 represents 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 conductive brush 9b, and by rubbing the brush 9b on the recording sheet 5 at an appropriate angle and distance, the cleaning member 9 adheres to the recording sheet 5. This is to scrape off the toner 2 on the sleeve 3. In this embodiment, the cleaning member 9 is made of carbon fiber and has a volume resistivity of 100.
~103 Ωcm was used.

Further, a non-magnetic member 11 for supporting the recording sheet 5 and a magnet 12 for collecting the toner 2 are disposed at a position facing the cleaning member 9 with the recording sheet 5 interposed therebetween. There is.

Reference numeral 13 denotes a power source for applying a voltage having a polarity opposite to the electric charge generated when the cleaning member 9 rubs the recording sheet 5.

The toner 2 attached to the outer periphery of the sleeve 3 by the rotating magnet 4 is transported through the through hole 1e of the substrate 1a.
and is transported onto the recording electrode 1. At this time, by applying a voltage to the recording electrode 1 according to the image information,
An image can be formed by adhering the toner 2 to the recording sheet 5. Note that the toner 2 that does not contribute to image formation on the recording electrode 1 falls from the circumferential surface of the sleeve 3 and does not affect the image formed on the recording sheet 5.

The image formed on the recording sheet 5 is as follows:
The rotation of the drive roller 6a causes the recording sheet 5 to move as shown in FIG.
The image is conveyed in the direction of arrow b, and is displayed externally when passing through the image display section 8. Then, the recording sheet 5 that has passed through the image display section 8 has the adhering toner 2 removed by the cleaning member 9 and its charging history is erased. Then, the toner 2 falls onto the sleeve 3 and is conveyed again in preparation for the next recording.

Next, the configuration of the image recording section in the apparatus will be explained with reference to FIG. In FIG. 1, reference numeral 14 denotes a regulating member which is a compression means for compressing the toner 2 accumulated between the recording electrode 1 and the recording sheet 5. The volume V1 of the toner storage chamber constituted by the regulating member 14, the recording sheet 5, and the recording electrode 1 is the toner volume VV= corresponding to the toner amount WA (t≧t1) that would be accumulated in the absence of the regulating member 14. 1/ρ{Wθ/360 +ρ(A2 −A1)π
D}. (t1: Time required for the toner 2 to rotate once on the sleeve 3, ρ: Toner density, D: Sleeve diameter, W: Total weight of toner on the sleeve surface, θ: Between the toner through hole 1e and the exposed conductor portion 1d. (A2: total area of toner through hole 1e, A1: total area of gap between recording electrode 1 and recording sheet 5)

002
8] In the above configuration, when the rotary magnet 4 is rotated to make it possible to convey toner, the conductor exposed portion 1 is moved as in the conventional example.
Toner 2 is dammed up and accumulated before d. This accumulated toner 2 is forcibly stored in the toner storage chamber constituted by the regulating member 14, the recording sheet 5, and the recording electrode 1, so that the toner density ρ1 in the storage chamber is ρ
1=WA/V1.

On the other hand, the dammed toner density ρ in the absence of the regulating member 14 is ρ=WA/V. Here, since V1 <V, ρ1 >ρ. That is, the provision of the regulating member 14 increases the toner density. This indicates that the toner 2 in the toner storage chamber has been compressed, and as a result, the toner resistance value is reduced and the image density can be increased.

The basic factors that increase the image density when the toner 2 is dammed up in this way are: (1) the amount of toner in contact with the surface of the image effective area of the recording sheet 5 increases;
2) This is because the electrostatic attraction force between the recording sheet 5 and the toner 2 increases, and the amount of toner attracted to the recording sheet 5 increases. These reasons will be explained below in comparison with the case where the toner 2 is not dammed.

(1) Regarding the increase in the amount of surface contact toner with respect to the effective image area of the recording sheet 5, the toner 2 on the exposed conductor portion 1d forms a chain along the lines of magnetic force formed by the rotating magnet 4. 4. Since the distance from the surface of the recording sheet 5 is larger than that of the exposed conductor portion 1d, the magnetic flux density on the surface of the recording sheet 5 is smaller than that on the surface of the exposed conductor portion 1d, and as a result, as shown in FIG. As shown in FIG. 2, the toner chain has an open shape on the surface of the recording sheet 5. When a voltage according to image information is applied between the exposed conductor portion 1d and the conductive layer 5c of the recording sheet 5 in this state, the effective image area on the surface of the recording sheet 5 facing the exposed conductor portion 1d is Since there is a region where the tip of the toner chain is not in contact, the density becomes thinner when outputting a solid black pattern.

Therefore, as shown in FIG. 17, when a toner dam is formed in front of the exposed conductor portion 1d while the toner 2 is being conveyed, the area where the leading end of the toner chain is not in contact with the image effective area of the recording sheet 5 is Since the toner 2 also enters, the opening of the toner chain is corrected and the density becomes higher when outputting a solid black pattern.

(2) Regarding the increase in the electrostatic adsorption force between the recording sheet 5 and the toner 2 and the increase in the amount of toner attracted to the recording sheet 5, FIG. 6 schematically shows the principle of image recording. A diagram,
A state in which the conductor exposed portion 1d and the recording sheet 5 are connected by a toner chain is shown. Turn on switch S1 and use toner 2.
When a positive charge is injected into the recording sheet 5, a negative charge is simultaneously induced in the conductive layer 5c of the recording sheet 5, and an electrostatic attraction force FE acts between the toner 2 and the recording sheet 5. On the other hand, the toner chain receives a force FM in a direction opposite to the electrostatic attraction force FE due to the magnetic field formed by the rotating magnet 4. By setting each parameter so that FE > FM, the toner 2 at the tip of the toner chain can be electrostatically attached to the surface of the recording sheet 5.

The electrostatic adsorption force FE will be further considered. FIG. 7 shows a schematic electric circuit of the image recording section. In the figure, R1 is the conductor resistance of the toner chain between the recording sheet 5 and the recording electrode 1, R2 is the resistance as a conductor of the recording sheet 5, C is the capacitance as a dielectric of the recording sheet 5, E is the recording voltage, and i1 , i2 , i3 are the resistances R
1, R2 and the current flowing through capacitor C. When switch S1 is turned on, R1 i1 +R2 i2 = E 1/C∫i3 dt=R2 i2 The voltage EC applied to both ends of the capacitor is
1 After t seconds after turning ON, EC = R2 i2 = R2 E/(R1 + R2)
(1-ε-K)K=(R1 +R2)t/CR1 R
2, and a graph of this is shown in FIG. Therefore, at t = ∞ (infinity), EC = R2 E
/(R1 +R2), it can be seen that the value is constant. Therefore, it can be seen that the smaller the conductor resistance R1 of the toner chain, the larger the voltage EC applied across the capacitor, and the shorter the rise time until it reaches a constant value.

Further, the amount of charge stored at both poles of the capacitor C is Q=CEC, and as the value of EC increases, the value of Q also increases. In addition, the electrostatic attraction force FE between the charges stored at both poles of the capacitor C is FE
=Q2/2ε0 S, so as the value of Q increases, the value of FE also increases. If EM is the minimum EC required for image quality, then EM ≦R2 E/(R1 + R2 ), so R1 ≦R2 (E/EM −1)=RM In order to lower the conductor resistance R1 above the specified value RM, the above-mentioned The toner 2 is blocked in front of the exposed conductor portion 1d.

The damming state of the toner 2 will be expressed quantitatively. FIG. 9 is an explanatory diagram showing the state before and after the toner is dammed up. Below, the surface of the sleeve 3 is shown in part A (through hole 1e - conductor exposed part 1d: center angle θ of sleeve 3).
), B part (conductor exposed part 1d - through hole 1e: center angle 2π-θ of sleeve 3). In addition, W is the total weight of toner on the surface of the sleeve 3, V is the toner conveyance speed, and A1
is the cross-sectional area between the recording sheet 5 and the exposed conductor portion 1d, A2
is the area of the through-hole 1e, ρ is the toner density, and D is the diameter of the sleeve 3.

The rotary magnet 4 is rotated with the recording sheet 5 sufficiently separated from the sleeve 3 to constantly transport the toner 2 on the surface of the sleeve 3. Next, the recording sheet 5 is brought close to the sleeve 3, and the distance between the recording sheet 5 and the exposed conductor portion 1d is set to a predetermined gap value, and then after t seconds, the section A,
Find the toner weight of part B. In the A part, WA = W × θ / 2π + ρ (A2 - A1) In the VtB part, WB = W × θ / (2π - θ) / 2π - ρ (A2
-A1) Vt. Here, toner 2 is applied to sleeve 3.
Since the toner 2 circulates on the sleeve 3, if the time required for the toner 2 to make one rotation on the sleeve 3 is t1, then t1 = πD/V, and the amount of toner after t1 seconds is a constant amount, that is, W
At1=W×θ/2π+ρ(A2 −A1) In the πDB part, WBt1=W×θ/(2π−θ)/2π−ρ(A2
-A1) It becomes steady state at πD.

FIG. 10 is an enlarged view showing the case where the toner 2 is dammed up in the image recording section and a steady state is reached. Let us consider the force applied to the toner 2 in the image effective area EFGH, with the starting and ending points of the image effective area being E and F on the recording sheet 5 side and G and H on the conductor exposed portion 1d side along the toner transport direction.

The shape of the image effective area EFGH is shown in FIG.
1, the square EFGH is approximated by a square EFGH, and if the angle between the line segment EF and the line segment GH is θ1, then the square EFGH constitutes a part of a wedge shape with respect to the toner transport direction. When a force P acts perpendicularly to the line segment EG, the toner 2 in the square EFGH receives a force of P/2 (sin θ1/2) perpendicularly to the line segments EF and GH, respectively.

As mentioned above, the toner 2 is stopped in front of the conductor exit portion 1d after a certain period of time t1, and its weight is reduced to WAt.
1, so the force P is approximated to the force that the wall receives when an object with weight WAt1 hits the wall perpendicularly at a velocity V (
P∝WAt1V). Therefore, the toner 2 in the image effective area EFGH is dammed up in front of the conductor exposed portion 1d, so that the compressive force P/2 (sin θ1
/2).

On the other hand, when the toner 2 is compressed, its resistance tends to decrease as shown in FIG. That is, since the toner in the image effective area EFGH is blocked in front of the exposed conductor portion 1d, the toner resistance R1 is lowered and the electrostatic attraction force FE is increased compared to the case where the toner is not blocked. Then, the toner resistance R1 is lowered from the specified value RM, resulting in the electrostatic attraction force FE acting on the toner chain.
It can be seen that FM becomes larger than the magnetic force FM of the rotating magnet 4 that tries to hold the toner chain on the sleeve 3 side, and the amount of toner 2 attracted to the recording sheet 5 increases.

[0042] If the width of the device is increased,
Since the accuracy of the drive roller 6a and the sleeve 3 deteriorates, it is necessary to widen the gap between the recording sheet 5 and the recording electrode 1. At this time, the resistance R1 of the toner chain increases because it is proportional to the distance, and in order to obtain the desired image density, it is necessary to satisfy R1≦RM. Conventionally, this has been achieved by increasing the toner conveying speed V, or by increasing the outer diameters of the drive roller 6a and the sleeve 3, respectively, as shown in FIG.
There is a method of increasing the toner compression force by decreasing the tip angle θ1 of H. In the former case, the size must be increased in order to increase the output of the drive source for the drive roller 6a, and power consumption also increases. In addition, in the latter case, the entire device becomes larger and heavier, and the sleeve 3 and the recording sheet 5 are placed close to each other after image recording, so the toner chain on the sleeve 3 is attached to the recording sheet 5.
There was a risk that the toner 2 adhering to the surface would be stroked and cause unevenness in the image.

On the other hand, in this embodiment, since the toner compression force is increased by the regulating member 14, the resistance R1 of the toner chain is set to be equal to or less than the specified value RM in accordance with the gap expansion rate between the recording sheet 5 and the recording electrode 1. Therefore, the toner transport speed V,
The increase in the outer diameters of the drive roller 6a and sleeve 3 can be reduced.

Next, another embodiment of the image recording section in the display device will be described. The general configuration of the entire device is the same as that of the previous embodiment. First, in the configuration shown in FIG. 14, a regulating member 15 that regulates the space occupied by the toner blocked upstream of the exposed conductor portion 1d of the recording electrode 1 is configured to be movable in synchronization with an image control signal. That is, the regulating member 15 is configured to be retracted to the position shown by the two-dot chain line in the figure when not recording an image, and to move to the position shown by the solid line when recording an image.

When the regulating member 15 is retracted, the volume V2 of the toner storage chamber constituted by the regulating member 15, the recording sheet 5, and the recording electrode 1 is the same as that of the image recording section when the regulating member 15 is not present. Toner amount WA (t
≧t1 ) corresponding toner volume V V=1/ρ{Wθ/360 +ρ(A2 −A1 )π
D}. Further, the volume V3 of the toner storage chamber formed by the regulating member 15, the recording sheet 5, and the recording electrode 1, which is formed by the regulating member 15 moving during image recording, is the same as the volume V3 of the toner storage chamber formed by the regulating member 15, the recording sheet 5, and the recording electrode 1. It is set to be smaller than the toner volume V corresponding to the stopped toner amount WA (t≧t1). That is, the volume of the toner storage chamber is set so that V3<V<V2. Therefore, the toner density in the toner storage chamber satisfies ρ2 < ρ < ρ3.

According to the above configuration, the toner density is increased by increasing the toner storage capacity during non-image recording and by moving the regulating member 15. Thereby, the compression effect of the toner 2 in the toner storage chamber can be enhanced and the image density can be increased. Further, the cleaning member 9
In order to reuse the toner 2 scraped off from the recording sheet 5, the passage leading to the toner damming part is kept open when not recording an image and closed when recording an image. 2 can be compressed without exception.

As shown in FIG. 15, it is also possible to provide a plurality of projections 15a on the toner storage chamber side of the regulating member 15 at predetermined intervals in the longitudinal direction. In this case, by stirring the toner 2 dammed up in response to the movement of the regulating member 15 by the protrusion 15a, the toner 2 deteriorates due to repeated use and hardens at the dammed up portion, making it impossible to form an image. It is possible to prevent this and extend the life of the device.

[0048]

[Effects of the Invention] As described above, since the present invention is provided with a compression means for compressing the developer accumulated between the recording electrode and the recording medium, the degree of compression of the developer can be improved. . Thereby, the developer transport speed for obtaining the necessary compressive force of the developer can be reduced. Therefore, the power source for driving the developer conveying means can be saved and the entire apparatus can be downsized. In addition, when the developer conveyance speed is not changed, the conductor resistance of the developer is within the range below the specified value (decreased resistance due to increase in developer compressive force + increased resistance due to increase in gap ≦ specified value). The amount of gap between recording electrodes can be increased. Therefore, unnecessarily high precision of parts such as the drive roller and sleeve is not required, so yield can be improved and costs can be reduced. In addition, when the width of the device is increased, the accuracy of the drive roller and sleeve components decreases, so the gap between the recording medium and the recording electrode must be increased, but the resistance increases in proportion to the gap expansion rate. In order to keep the value below the specified value, the developer transport speed, the increase in the outer diameter of the drive roller, and the sleeve can be reduced. Therefore, the drive source for the drive roller can be downsized, power consumption can be reduced, and the weight of the entire device can be reduced. Furthermore, by increasing the distance between the sleeve surface and the recording medium even after image formation, the area where the developer on the sleeve strokes the developer attached to the recording medium can be reduced, thereby reducing image unevenness. can. Furthermore, being able to change the developer transport speed as described above can be a means of avoiding resonance points of the entire apparatus.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of an image recording section.

FIG. 2 is a cross-sectional explanatory diagram showing a schematic configuration of an image forming apparatus.

FIG. 3 is a perspective explanatory diagram of an image recording section.

FIG. 4 is a partially enlarged sectional view of a recording medium.

FIG. 5 is a schematic cross-sectional view when there is no toner dam in the image recording section.

FIG. 6 is a schematic explanatory diagram showing the principle of image recording.

FIG. 7 is a schematic explanatory diagram showing the principle of image recording.

FIG. 8 is a graph showing the relationship between voltage applied to a recording sheet and time.

FIG. 9 is an explanatory diagram showing before and after the toner is dammed up in the image recording section.

FIG. 10 is an enlarged explanatory diagram when toner is dammed up in the image recording unit and a steady state is reached.

FIG. 11 is a schematic illustration of pressure applied to toner.

FIG. 12 is a graph showing the relationship between toner compression force and toner volume resistance value.

FIG. 13 is an explanatory diagram when the drive roller diameter and sleeve diameter are increased.

FIG. 14 is a schematic cross-sectional view showing another example of the image recording section.

FIG. 15 is a perspective view showing another example of the regulating member.

FIG. 16 is an explanatory diagram of a conventional display device.

FIG. 17 is an explanatory diagram of the image recording section before improvement.

[Explanation of symbols]

1 Recording electrode 1a Cover film 1b Board 1c Drive element 1d Conductor exposed part 1e　　　Through hole 2 Toner 3 Sleeve 4 Rotating magnet 5 Record sheet 5a Surface layer 5b White layer 5c Conductive layer 5d Base material 6a Drive roller 6b Tension roller 7 Recording control section 8 Image display section 9 Cleaning parts 10　　　　　Backboard 10a Support member 11　　　　　Non-magnetic member 12 Magnet 13 Power supply 14, 15 Regulation member 15a Protrusion

Claims (5)

[Claims] 1. A recording electrode for applying a voltage to a developer according to image information, a recording medium that moves relatively to form an image by adhering the developer, and a recording electrode and a recording medium. An image forming apparatus comprising: a developer supply means for supplying developer between the recording electrode and the recording medium; and a compression means for compressing the developer accumulated between the recording electrode and the recording medium. 2. The image forming apparatus according to claim 1, wherein the compression means is a regulating member that regulates a space occupied by the accumulated developer. 3. The image forming apparatus according to claim 2, wherein the regulating member is movable in synchronization with an image control signal. 4. 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. 5. A display device in which the image formed on the recording medium is displayed on a display unit.
The image forming apparatus described above.