JP2000218845A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent variation of a position of a toner pass-through hole and waving movement of a toner passing control means and to prevent toner from adhering to be accumulated on a surface of the toner passing control means by returning from an image receiving means after flying to be adhered to the image receiving means, thereby forming a high quality image. SOLUTION: This image forming apparatus comprises a toner carrier body 1 and a toner pass-through control means 3 having a plurality of toner pass- through holes 4 and controlling the passing-through of toner 2. The upper side of the toner pass-through control means 3 is fixed and the lower side thereof is pulled by a spring 13, thereby preventing variation of positions of the toner pass-through holes 4. A portion of the toner pass-through control means 3 at the lower side with respect to the point contacting with the toner carrier body 1 is brought into contact with a stay 14, thereby preventing waving movement of the toner pass-through control means 3. A gap portion X that becomes greater as it goes to the lower side is provided between the toner pass-through control means 3 and an image receiving means 7.

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 applied to a copying machine, a facsimile, a printer, and the like. More particularly, the present invention relates to a toner passage control means controlled by an image signal to transfer toner from a toner carrier to a back electrode. Control the flight,
The present invention relates to an image forming apparatus that forms an image by attaching toner to an image receiving unit located between a toner passage control unit and a back electrode.

[0002]

2. Description of the Related Art In recent years, with the improvement of personal computer capabilities and the advancement of network technology, there has been an increasing demand for printers and copiers capable of handling a large amount of documents and capable of handling color documents. ing. However, an image forming apparatus capable of outputting satisfactory high-quality black and white or color documents and having a high processing speed is under development and is expected to appear.

As one of them, there is a so-called "toner jet (registered trademark)" type image forming technique in which toner is caused to fly onto image receiving means such as recording paper or an intermediate image carrying belt by the action of an electric field to form an image. Are known.

An image forming apparatus of this kind is disclosed in
No. 4-26333 and U.S. Pat. No. 3,689,935.
Japanese Unexamined Patent Application Publication No. 60-20747 and Japanese Patent Publication No. 9-500842 are known. One example is Japanese Patent Application No. 10-100780.
What is disclosed in the above item will be described with reference to FIG.

In FIG. 6, reference numeral 31 denotes a grounded toner carrier which carries and conveys charged toner, and 32 denotes a regulating blade which controls the toner on the toner carrier 31 in one to three layers and further charges the toner. . A supply roller 33 supplies the toner to the toner carrier 31 and charges the toner. Numeral 34 denotes a toner passage control means.
5 are formed, and a control electrode 36 is provided therearound. A voltage corresponding to an image signal is applied to the control electrode 36 from a control power supply 37. 38 is a back electrode, 39
Is a back electrode power supply. Reference numeral 40 denotes an image receiving unit such as a recording paper conveyed on the back electrode 38.

In the above-described configuration, the supply roller 33 and the toner carrier 31 are operated to form a uniform toner layer on the toner carrier 31 by the regulating blade 32 and to convey the toner. Apply voltage to 38,
When a voltage corresponding to an image signal is applied to the control electrode 36 by a control power supply 37 such as a drive IC while moving the image receiving means 40 in synchronization with the movement, the toner on the toner carrier 31 responds to the image signal. Then, the toner flies and adheres to the image receiving means 40 through the toner passage hole 35, and a required image is formed on the image receiving means 40.

By the way, for example, 6
In order to form a fine image of 00 dpi (a density of 600 dots per inch), it is necessary to arrange the toner passage holes 35 at such a pitch in the toner passage control means 34. As shown in FIG. 8, the toner passage holes 35 and the control electrodes 36 are arranged in many rows (eight rows in the illustrated example). The toner passage hole 35 and the control electrode 36 are circular, and connection electrodes connected to the respective control electrodes 36 extend on both sides in the moving direction of the toner carrier 31 to avoid mutual interference, and drive I and V output control voltages.
It is connected to the C lead.

FIG. 6 shows an example in which the image receiving means 40 is made of recording paper or the like, and an image is formed directly on the recording paper or the like. In the case of a color printer, there are problems such as difficulty in synchronizing the image forming timing of each color due to variations in the conveyance of recording paper and deterioration of image quality. As disclosed in JP-A-100780, it may be preferable to use an intermediate image carrying belt as the image receiving means 40 and to transfer the images formed on the image carrying belt to recording paper or the like at once. .

Referring to FIG. 7, reference numeral 43 denotes an endless image carrying belt as image receiving means 40, which is made of a film having a resistance of about 10 ¹⁰ Ω · cm in which a conductive filler is dispersed in a resin. It is wound between a pair of rollers 44a and 44b. Reference numeral 45 denotes a recording sheet 46 from the sheet feeding tray.
A pick-up roller 47 that feeds each sheet; a timing roller 47 that synchronizes the image position with the fed recording paper 46;
Reference numeral 48 denotes a transfer roller for transferring the toner image formed on the image carrying belt 42 onto the recording paper 46. The transfer roller 48 is pressed toward the roller 44a with the image carrying belt 43 interposed therebetween, and a transfer voltage is applied. . A fixing device 49 fixes the toner image on the recording paper 46 by heating and pressing the recording paper 46 onto which the toner image has been transferred.

[0010]

In the above-described image forming apparatus, the distance between the toner carrier 31 and the toner passage control means 34, ie, the distance between the toner carrier 31 and the control electrode 36, is reduced. Since the amount of toner passing through the toner passage hole 35 is greatly affected by the interval, for example, in JP-A-9-500842,
Although the spacing is maintained by disposing a scraper blade between the toner carrier 31 and the toner passage control means 34, the toner carrier 31 and the toner passage control generated by the eccentricity of the rotation axis of the toner carrier 31. The change in the contact pressure with the means 34 disturbs the toner layer on the toner carrier 31. Therefore, for example, in Japanese Patent Application Laid-Open No. HEI 8-118706, the toner passage control means 34 is fixed via the elastic fixing means, but the toner passage control means 34 and the moving toner carrier 31 at the contact point. Of the toner passage hole 3 due to the fluctuation of the toner passage control means 34 generated by the frictional force of
The position fluctuation of No. 5 occurs, and the flying of the toner passing through the toner passage hole 35 is disturbed, thereby deteriorating the image quality.

Further, since the toner passage control means 34 is composed of several kinds of different materials, the surface of the toner passage control means 34 is wavy due to tension, and the distance between the toner carrier 31 and the toner passage control means 34 is in the toner passage hole row direction. And the image quality is degraded.

Further, since the toner passage control means 34 and the image receiving means 40 are normally close to each other at a distance of 100 μm to 500 μm, the toner on the toner carrier 31 is transferred to the toner passage control means 34 according to the image signal. After flying and adhering to the image receiving means 40 through the hole 35, the image receiving means 4
There is a problem that it returns from zero, adheres and accumulates on the surface of the toner passage control means 34, drops on the image, and degrades the image quality.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, the present invention prevents the toner passage hole from fluctuating in position, prevents the toner passage control means from waving, and returns from the image receiving means after flying and adhering onto the image receiving means. It is an object of the present invention to provide an image forming apparatus capable of forming a high quality image by preventing the toner from being deposited on the surface of the toner passage control unit.

[0014]

According to a first aspect of the present invention, there is provided an image forming apparatus having a toner carrier which carries and moves a charged toner, and a plurality of toner passage holes for passing the toner. A toner passage control unit for applying an image signal to a control electrode disposed so as to surround the periphery to control the passage of toner, an image receiving unit to which the passed toner is applied, and a back surface of the image receiving unit. An image forming apparatus having a back electrode for sucking toner, wherein the toner passage control means is fixed on the upstream side in the toner carrier moving direction from a contact point with the toner carrier, and the elastic member is provided on the lower side in the toner carrier moving direction. The toner generated by the frictional force at the point of contact between the toner passage control means and the moving toner carrier by fixing the upper side is fixed. Is prevented fluctuation of excessive control means, it is possible to prevent the positional fluctuation of the toner passage hole to form a high quality image.

Further, an image forming apparatus according to a second aspect of the present invention has a toner carrier that carries and moves charged toner, and has a plurality of toner passage holes through which the toner passes, and is disposed so as to surround the periphery thereof. A toner passage control unit that controls the passage of the toner by applying an image signal to the control electrode, an image receiving unit to which the passed toner is applied, and a back electrode that is disposed on the back of the image receiving unit and sucks the toner. Wherein the toner passage control means is brought into contact with a stay extending in a direction orthogonal to the toner carrier moving direction on the side lower than the toner carrier moving direction from the contact point with the toner carrier, By causing the toner passage control unit to come into contact with the stay on the lower side in the toner carrier moving direction from the point of contact with the toner carrier, the toner passage control unit can be wavy due to tension. Deformation can be prevented, the distance between the toner carrier and the toner passage control means can be made constant in the direction of the row of toner passage holes, the amount of toner passing through each toner passage hole becomes uniform, A quality image can be formed.

The image forming apparatus according to a third aspect of the present invention has a toner carrier that carries and moves the charged toner, and has a plurality of toner passage holes through which the toner passes, and is disposed so as to surround the periphery thereof. A toner passage control unit that controls the passage of the toner by applying an image signal to the control electrode, an image receiving unit to which the passed toner is applied, and a back electrode that is disposed on the back of the image receiving unit and sucks the toner. An image forming apparatus comprising: a toner passage control unit that contacts a toner passage through spacer means provided at a position on the toner passage control unit that is on the upper side in the toner carrier movement direction with respect to the toner passage hole; The means is brought into contact with a stay extending in a direction orthogonal to the toner carrier moving direction on the lower side in the toner carrier moving direction from the contact point with the toner carrier. Take the deposition.

Accordingly, since the toner passage control means makes contact with the stay on the lower side in the toner carrier moving direction with respect to the contact point with the toner carrier, the wavy deformation caused by the tension applied to the toner passage control means is prevented. At the same time, the spacers can be uniformly pressed against the toner carrier over the entire row of toner passage holes, thereby preventing the formation of a gap between the spacers and the toner carrier and allowing the toner carrier to pass through the toner carrier. The distance between the spacer and the control means can be made constant in the direction of the row of toner passage holes to the thickness of the spacer. Thus, the amount of toner passing through each toner passage hole becomes uniform, and a high-quality image can be formed.

According to a fourth aspect of the present invention, there is provided an image forming apparatus having a toner carrier for carrying charged toner and moving, and a plurality of toner passage holes for passing the toner and surrounding the periphery thereof. A toner passage control unit that controls the passage of the toner by applying an image signal to the control electrode, an image receiving unit to which the passed toner is applied, and a back electrode that is disposed on the back of the image receiving unit and sucks the toner. An image forming apparatus having a separation portion that gradually increases from the toner passage hole toward the lower side of the image receiving unit between the toner passage control unit and the image receiving unit; After the toner flies and adheres to the image receiving means through the toner passage hole of the toner passage control means in accordance with the image signal, it prevents a phenomenon that the toner returns to the toner passage control means from the image receiving means. No image stain, it can form a high quality image.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the image forming apparatus of the present invention will be described below with reference to FIGS.

In FIG. 1, which shows a schematic configuration of the image forming apparatus according to the present embodiment, reference numeral 1 denotes a toner carrier which carries and conveys charged toner 2 and comprises a grounded rotatable sleeve, The charged toner 2 is set to the ground potential and is adsorbed in a thin state of one to three layers.

Reference numeral 3 denotes a toner passage control means, which is constituted by a flexible printed circuit board whose effective width corresponds to the effective width of the toner carrier 1 and which is fixed on the upper side in the toner carrier moving direction from the point of contact with the toner carrier 1. And is fixed via a spring 13 on the lower side. The contact pressure between the toner carrier 1 and the toner passage control means 3 generated by the spring 13 at this time is suitably 0.2 to ² gf / mm ² . This is because the distance between the toner carrier 1 and the toner passage control means 3 at the toner passage hole point is always maintained.
This is because the toner carrier 1 and the toner passage control means 3 must always be in contact in the same state following the eccentricity of the rotation axis of the toner carrier 1, and the toner carrier 1
This is because the upper toner layer must not be deformed. This contact pressure slightly varies depending on the material of the toner carrier 1 and the toner passage control means 3 and the like. Reference numeral 4 denotes a toner passage hole.

Reference numeral 6 denotes a back electrode disposed so as to face the toner carrier 1 with the toner passage control means 3 interposed therebetween. Reference numeral 7 denotes an image receiving unit such as a recording paper or an image carrying belt which is conveyed in a direction indicated by an arrow a on a fixed path between the back electrode 6 and the toner passage control unit 3. Reference numeral 12 denotes a toner passage control means 3 which is disposed on the surface facing the toner carrier 1 including a contact point with the toner carrier 1 and is located on the upper side in the toner carrier moving direction from there. It is a spacer for keeping the interval of the passage control means 3 constant.

A stay 14 extends straight in a direction perpendicular to the direction of movement of the toner carrier.
The toner passage control means 3 contacts the stay 14 and is slightly bent at the position of the stay 14. Although the configuration of the toner passage control means 3 will be described in detail later, the toner passage control means 3 is usually made of a flexible resin film including a control electrode and is made of different materials having different elastic coefficients. This causes a phenomenon that the film undulates. Therefore, by bringing the toner passage control means 3 into contact with the stay 14, the waving near the contact point with the stay 14 is eliminated, and by slightly bending the stay, the contact pressure is increased and the effect is enhanced.

Further, as described above, by preventing the toner passage control means 3 from waving, the spacers 12 provided in the toner passage control means 3 can be uniformly formed on the toner carrier 1 over the entire toner passage hole row direction. , And the occurrence of a gap between the spacer 12 and the toner carrier 1 can be prevented. Thereby, the distance between the toner carrier 1 and the toner passage control means 3 can be made constant in the direction of the toner passage hole array in the thickness of the spacer 12. Normal,
The distance from the contact point between the toner passage control means 3 and the toner carrier 1 to the stay 14 is about 10 mm.
The effect diminishes as you move away from the point of contact with 4,
It is desirable to be as short as possible.

As shown by the broken line in FIG. 1, the stay 14 gradually moves between the toner passage control means 3 and the image receiving means 7 from the toner passage hole 4 toward the lower side in the moving direction of the image receiving means 7. It is arranged so that the separated portion X that becomes larger is formed. This is to prevent a phenomenon that the toner flying and adhering to the image receiving unit 7 through the toner passage hole 4 returns to the toner passage control unit 3 from the image receiving unit 7.

As shown in FIG. 2, the toner passage control means 3 includes a main film 8 having a thickness of about 50 μm and
10 pasted with an adhesive layer of about 0 to 15 μm thickness
It is composed of a three-layer polyimide resin film composed of upper and lower cover films 9a and 9b having a thickness of about 30 μm. Of course, the material and dimensions of each film, the number of constituent layers, and the like are not limited thereto, and may be arbitrarily designed. In the illustrated example, the toner passage hole 4 is located at an appropriate distance from the point of contact between the toner carrier 1 and the toner passage control means 3 in the movement direction of the toner carrier 1 in the movement direction of the toner carrier 1. They are arranged in two rows.

A control electrode 10 is provided on the upper surface of the main film 8 so as to surround each toner passage hole 4.
A pair of deflection electrodes 11a and 11b are provided on the lower surface of the main film 8 so as to surround the toner passage hole 4 from both sides. These electrodes 10, 11 a, and 11 b are formed of a Cu film having a thickness of about 8 to 20 μm, which is patterned on the main film 8.

Although the shape of the toner passage hole 4 is circular as shown in FIG. 5A, it may be oval or elliptical. Dimensionally, the diameter is set to about 70 to 120 μm. Further, the surface roughness R of the inner peripheral wall surface of the toner passage hole 4 is 0.1 to less than the average particle diameter of the external additive of the toner 2.
It is 0.5 μm or less. Drilling with such a surface roughness R is possible by drilling with an excimer laser or press working.
After drilling with an O ₂ laser or the like, post-processing such as etching may be performed.

It is preferable that the control electrode 10 around the toner passage hole 4 has a shape corresponding to the planar shape of the toner passage hole 4 as shown in FIG. Further, as shown in FIG. 5B, the deflecting electrodes 11a and 11b are shared by the adjacent toner passage holes 4.

In the above configuration, the voltage Vp applied to each control electrode 10 during the image forming operation is, for example, -50.
V, 200 V and 250 V, the deflection electrodes 11 a and 11
The applied voltages V _DD-L and V _DD-R for b are, for example, 150
The voltage is switched between V, 0 V, and -150 V at the timing shown in FIG. 4, and the voltage applied to the back electrode 6 is, for example, 1000 V.

In FIG. 4, the deflection electrodes 11a, 11b
Are 0 V, the control electrode 10 is set to −50 V, and the electric field generated by the back electrode 7 is applied to the toner 2
First, +150 V is applied to the left deflection electrode 11a, and -150 V is applied to the right deflection electrode 11b.
In a state in which the charged toner 2 is deflected to the left by applying V, a voltage of 250 V is first applied to the control electrode 10 to peel off the toner 2 adsorbed on the toner carrier 1, and then the 200 V By applying the voltage of
As shown in FIG. 3A, the toner 2 passes through the toner passage hole 4 and deflects to the left, flies, and is, for example, about 40 μm on the left side of the position facing the toner passage hole 4 on the image receiving means 7. The toner is applied to the displaced position. Next, in a state where both the left and right deflection electrodes 11a and 11b are set to 0V, a voltage is applied to the control electrode 10 in the same manner as described above, so that the toner passing through the image receiving means 7 is changed as shown in FIG. The toner 2 is applied to a position facing the hole 4.
Next, while applying -150 V to the left deflection electrode 11a and +150 V to the right deflection electrode 11b to deflect the negatively charged toner 2 to the right, a voltage is applied to the control electrode 10 in the same manner as described above. As a result, as shown in FIG. 3C, the toner is applied to a position on the image receiving unit 7 which is displaced by about 40 μm to the right from the position facing the toner passage hole 4. Thus, the control electrode 10 and the deflection electrode 11
The toner is applied to three points, that is, the left, right, and center in one toner passage hole 4 by sequentially switching the applied voltages to a and 11b.

When the toner 2 is prevented from passing through the toner passage hole 4, the voltage applied to the control electrode 10 is temporarily changed from -50V to 0V as shown by the imaginary line. The control electrode moves in such a manner that the toner 2 charged to the opposite polarity (+ polarity) and deposited on the surface of the toner passage control means 3 is attracted to the toner carrier 1 and returns to the negatively charged toner 2 side. The negatively charged toner 2 accumulated above the core 10 prevents the charged toner 2 from accumulating around the toner passage hole 4 and causing clogging of the toner passage hole 4.

[0033]

According to the image forming apparatus of the present invention, as is apparent from the above description, the toner passage control means is fixed on one side on the upper side in the toner carrier moving direction from the contact point with the toner carrier. By stretching the lower side with the tension of a spring or other elastic member, it is possible to prevent the toner passage control means from fluctuating due to the frictional force at the contact point between the toner passage control means and the moving toner carrier, A change in the position of the toner passage hole can be prevented, and a high-quality image can be formed.

Further, the toner passage control means is brought into contact with a stay extending in a direction orthogonal to the toner carrier moving direction on the lower side in the toner carrier moving direction from the contact point with the toner carrier, thereby generating the toner passage control means. Can be prevented, the distance between the toner carrier and the toner passage control means can be made constant in the direction of the row of toner passage holes, and the amount of toner passing through each toner passage hole becomes uniform. And a high quality image can be formed.

Further, the toner passage control means is brought into contact with the toner carrier via a spacer provided at a position on the toner passage control means which is on the upper side in the toner carrier movement direction with respect to the toner passage hole. By contacting the means with a stay extending in a direction orthogonal to the toner carrier moving direction on the lower side of the toner carrier moving direction from the point of contact with the toner carrier, the occurrence of a gap between the spacer and the toner carrier is prevented, The distance between the toner carrier and the toner passage control means can be constant in the toner passage hole row direction,
A high-quality image in which the amount of toner passing through each toner passage hole is uniform can be formed.

Further, by providing a separation portion between the toner passage control means and the image receiving means which gradually increases from the toner passage hole toward the lower side of the image receiving means, it is possible to pass through the toner passage hole of the toner passage control means. After flying and adhering onto the image receiving means, the phenomenon of returning from the image receiving means to the toner passage control means can be prevented, and a high-quality image free from image contamination can be formed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of an embodiment of an image forming apparatus of the present invention.

FIG. 2 is an enlarged vertical sectional front view of a main part of the embodiment.

FIG. 3 is a vertical sectional side view showing three operation states in an arbitrary toner passage hole of the embodiment.

FIG. 4 is a timing chart of voltages applied to a control electrode and a deflection electrode in the same embodiment.

FIG. 5 shows an arrangement state of each electrode in the embodiment;
FIG. 3A is a plan view showing a state of arrangement of control electrodes, and FIG.

FIG. 6 is a main part configuration diagram of a conventional image forming apparatus.

FIG. 7 is a configuration diagram illustrating an overall configuration of a conventional image forming apparatus.

FIG. 8 is a plan view showing an arrangement state of each electrode in the conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Toner carrier 2 Toner 3 Toner passage control means 4 Toner passage hole 6 Back electrode 7 Image receiving means 10 Control electrode 12 Spacer 13 Spring 14 Stay X Separation part

 ────────────────────────────────────────────────── ─── Continuation of the front page (71) Applicant 597063831 Owneds Brygga 13 421 57 Vestro Fround a Sweden (72) Inventor Akira Kumon 1006 Oojidoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Kitaoka Yoshitaka 1006 Kazuma Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. (72) Inventor Akira Fukano 1006 Kadoma Kadoma, Kadoma-shi, Osaka Pref. Matsushita Electric Industrial Co., Ltd. Address Matsushita Electric Industrial Co., Ltd. (72) Akira Ryuji, inventor 1006 Oji Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Taichi Ito 1006, Oji Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. Terms (reference) 2C162 AE04 AE25 AE31 AE47 AE 56 AE74 AF07 AF19 AG01 AG07 AH15 AH64 AJ02 CA02 CA12 CA14 CA24 CA25 CA33

Claims (4)

[Claims] An image signal is applied to a control electrode having a plurality of toner passage holes through which a charged toner is moved and a plurality of toner passage holes for allowing the toner to pass therethrough. An image forming apparatus comprising: a toner passage control unit that controls the passage of toner through the image receiving unit; an image receiving unit to which the passed toner is applied; and a back electrode that is disposed on a back surface of the image receiving unit and sucks the toner. The image forming apparatus is characterized in that the passage control means is fixed on the upper side in the toner carrier moving direction from the point of contact with the toner carrier, and is fixed via an elastic member on the lower side in the toner carrier moving direction. 2. An image signal is applied to a control electrode which has a plurality of toner passage holes through which a charged toner is carried and moves and a plurality of toner passage holes for passing the toner and surrounds the periphery thereof. An image forming apparatus comprising: a toner passage control unit that controls the passage of toner through the image receiving unit; an image receiving unit to which the passed toner is applied; and a back electrode that is disposed on a back surface of the image receiving unit and sucks the toner. An image forming apparatus, wherein the passage control means is brought into contact with a stay extending in a direction orthogonal to the toner carrier moving direction on the lower side in the toner carrier moving direction from the point of contact with the toner carrier. 3. An image signal is applied to a toner carrier that carries the charged toner and moves, and a control electrode that has a plurality of toner passage holes through which the toner passes and that is arranged so as to surround the periphery thereof. An image forming apparatus comprising: a toner passage control unit that controls the passage of toner through the image receiving unit; an image receiving unit to which the passed toner is applied; and a back electrode that is disposed on a back surface of the image receiving unit and sucks the toner. The toner carrier is brought into contact with the toner carrier via a spacer provided at a position on the toner passage controller on the upper side in the toner carrier moving direction with respect to the passage hole, and the toner passage controller is moved from a contact point with the toner carrier. An image forming apparatus, wherein the stay is in contact with a stay extending in a direction perpendicular to the toner carrier moving direction on the lower side in the toner carrier moving direction. 4. An image signal is applied to a control electrode having a plurality of toner passage holes through which a charged toner is transferred and a plurality of toner passage holes for passing the toner, and which is arranged so as to surround the periphery thereof. An image forming apparatus comprising: a toner passage control unit that controls the passage of toner through the image receiving unit; an image receiving unit to which the passed toner is applied; and a back electrode that is disposed on a back surface of the image receiving unit and sucks the toner. An image forming apparatus, comprising a separation portion between the passage control means and the image receiving means, the distance gradually increasing from the toner passage hole toward the lower side of the image receiving means.