JP2003291392A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a toner image having a good image quality stably in an imaging apparatus where the gap between a toner carrier and a toner flight control means is regulated by touching a gap regulating means to a toner layer on the toner carrier. <P>SOLUTION: The gap between a toner carrier 12 and an FPC 4 is regulated by touching a spacer 5 being sandwiched between a toner layer TL on the toner carrier 12 and the FPC 4 to the toner layer TL in the touching region CR. The spacer 5 is provided with slots 51 corresponding to respective toner passing holes 41 and since the long side of each slot 51 is set longer than the width d of the touching region CR in the carrying direction D of the toner layer TL, toner being carried directly above the toner passing hole 41 does not touch the spacer 5. <P>COPYRIGHT: (C)2004,JPO

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 such as a copying machine, a facsimile and a printer, and more particularly to copying paper, transfer paper, copying paper and recording paper by controlling the toner flying from the toner carrier to the back electrode. The present invention relates to an image forming apparatus that forms an image by attaching toner to an image receiving body such as a transfer medium.

[0002]

2. Description of the Related Art As an image forming method using toner,
Conventionally, the jumping type and the projection type have been most widely used. In this type of image forming method, an electrostatic latent image corresponding to an image is formed on a photoconductor, and toner as an image forming agent is adhered to the electrostatic latent image on the photoconductor from a toner carrier such as a developing roller. To obtain a toner image, and then transfer the toner image to copy paper, transfer paper, copy paper,
It is to be transferred onto recording paper. However, these image forming methods require a step (photosensitive process) of forming an electrostatic latent image on the surface of the photoconductor, which involves a problem that the apparatus configuration is complicated and the apparatus cost and running cost are high. There is. Therefore, in recent years, as described in U.S. Pat. Nos. 3,689,935 and 5,036,341 and Japanese Patent Laid-Open No. 2001-505146, toner is copied by a function of an electric field, recording paper or intermediate paper. An image forming apparatus of a so-called "toner jet (registered trademark)" system, which forms an image by flying on an image receiving body such as a transfer belt, has been attracting attention.

In this image forming apparatus, a toner carrying member such as a developing roller for carrying toner in a predetermined moving direction is provided, and a toner regulating blade is provided so as to contact the surface of the toner carrying member. ing. Therefore, the toner on the toner carrier is triboelectrically charged by the toner regulating blade and, after being regulated to a predetermined thickness, is transported to the toner flying start position facing the back electrode.

Further, in this image forming apparatus, a flexible printed circuit board (Flexible Printed Circuit) having a plurality of toner passage holes for passing charged toner is disposed between the toner carrier and the back electrode. At the same time, an image receiver such as a recording paper or a transfer medium is arranged between the flexible printed circuit board and the back electrode. Then, a potential difference is applied between the toner carrier and the back electrode to form a transfer electrostatic field that causes the charged toner to fly from the toner carrier to the back electrode. Also,
In the flexible printed circuit board, control electrodes are arranged around each toner passage hole, and each toner passage hole is electrostatically opened / closed by controlling the voltage applied to each control electrode according to an image signal. Corresponding to the signal, the charged toner is caused to fly from the toner carrier to the back electrode through the toner passage hole and adhere to the image receiver. By doing so, a toner image corresponding to the image signal is formed on the image receiving body.

In this type of image forming apparatus, in order to stably form a toner image, it is necessary to keep the gap between the toner carrier and the flexible printed circuit board constant.
Therefore, as described in, for example, Japanese Patent No. 3045295, Japanese Patent Laid-Open No. 2000-211180, a spacer (gap defining means) is arranged on the upstream side in the moving direction with respect to the toner flying start position. Therefore, a gap management technique for keeping the above gap constant is proposed. That is, in this gap management technology,
The spacer is arranged so as to come into contact with the toner layer carried on the toner carrier at a position downstream of the toner regulation blade and upstream of the toner flying start position in the toner transport direction, whereby the toner carrier is supported. It defines the gap with the toner flight control means.

[0006]

By the way, in the image forming apparatus configured as described above, the toner layer regulated by the toner regulating blade always comes into contact with the spacer before being conveyed to the toner flying start position. In order to improve the image quality of the toner image, it is necessary to consider the influence of this contact on the toner image. Specifically, there are problems that the toner on the toner carrier is scraped off by the edge of the spacer, and the charge amount of the toner changes due to the friction with the spacer. It may become uniform and may cause image deterioration such as image stains and uneven density. However, in the conventional apparatus that manages the gap by the spacer, the influence of the contact of the spacer with the toner layer is not considered at all, and there is much room for improvement in improving the image quality.

The present invention has been made in view of the above-mentioned problems, and an image forming operation for defining the gap between the toner carrier and the toner flying control means by bringing the gap defining means into contact with the toner layer on the toner carrier. An object is to stably form a toner image with good image quality in the apparatus.

[0008]

In order to achieve the above object, an image forming apparatus according to the present invention carries a charged toner and moves the toner in a predetermined moving direction so that the toner reaches a toner flying start position. A toner carrier to be conveyed, a back electrode arranged to face the toner flying start position of the toner carrier, a toner passage hole is formed, and a space between the toner carrier and the back electrode is formed. The toner image is deposited on the image receiving body conveyed between the toner carrier and the back electrode by controlling the toner flying from the toner carrier to the back electrode through the toner passage hole. And a toner flying control means for forming a toner contact layer with the toner layer carried on the toner carrying body to define a gap between the toner carrying body and the toner flying control means. The toner carried in the hole facing region of the toner layer facing the toner carrier side opening end of the toner passage hole in the toner layer contacts the gap defining means. It is characterized in that it is configured to be conveyed to the toner flying start position without being.

In the invention thus constructed, the gap defining means contacts the toner layer on the toner carrier to keep the gap between the toner layer and the toner flying control means constant. Then, among the toners forming the toner layer sent to the toner flying start position, at least the toner carried in the hole facing area facing the opening end of the toner passing hole of the toner flying control means is allowed to fly without touching the gap defining means. It is transported to the starting position. Therefore, at least the toner conveyed to the hole facing area is not scraped off or the charge amount does not change in the middle, so that the uniformity of the toner layer is not disturbed, and the toner flying from the toner carrier to the back electrode is prevented. Can be performed with good controllability, and as a result, in this image forming apparatus, a toner image with good image quality can be stably formed.

As described above, in order to convey the toner carried in the hole facing area to the toner flying start position without touching the gap defining means, for example, the gap defining means is provided with the toner of the toner flying control means. A slot portion is provided to expose the carrier-side opening end and an adjacent region of the toner-flying-control-side surface located upstream of the opening end in the moving direction on the toner carrier-side surface to the toner carrier side. Good. In this case, of the toner conveyed from the upstream side along with the movement of the toner carrier, the toner in the hole facing area and the upstream side thereof is the toner passage hole and the slot portion provided in the upstream side. And the toner flight start position is reached without touching the gap defining means.

Further, in the case where at least one row of toner passage holes is provided in the toner flying control means in a width direction orthogonal to the moving direction, the gap is provided. The defining means is provided with an extending portion extending in the moving direction between the respective slot portions provided corresponding to each of the plurality of toner passage holes, and the toner layer is provided on the extending portion of the gap defining means. You may make it contact | abut. By doing so, the toner layer can be brought into contact with the extended portion of the gap defining means provided in the vicinity of the toner passage hole, and gap management can be performed with higher accuracy.

When the toner flight control means is provided with a plurality of toner passage holes, the gap defining means includes the plurality of toner particles on the toner carrier side surface of the toner flight control means. An opening for exposing a surface area including the opening end of the passage hole and an adjacent area located upstream of the opening end in the moving direction to the toner carrier side is provided, and the toner layer is moved by the moving member. You may make it contact | abut with the said gap definition means outside the both ends of the said opening part in the width direction orthogonal to a direction.

As described above, by providing the gap defining means with the opening for exposing the plurality of toner passage holes and the areas adjacent to the toner passage holes on the surface of the toner flight control means in the gap defining means, It is possible to prevent the toner transported to the printer from coming into contact with the gap defining means. Further, in this case, the gap can be kept constant by bringing the toner layer and the gap defining means into contact with each other outside the both ends of the opening.

[0014]

1 is a diagram showing an embodiment of an image forming apparatus according to the present invention. 2 is a block diagram showing an electrical configuration of the image forming apparatus of FIG. In this image forming apparatus, when an image signal is given to the main controller 101 of the control unit 100 from an external device such as a host computer, the main controller 1
The engine controller 102 controls each part of the developing device 1 in accordance with a signal from 01, so that the two rollers 21,
The toner flies and adheres to the intermediate transfer belt 23 that is stretched around the sheet 22 to form a toner image corresponding to the image signal. Thus, in this embodiment, the intermediate transfer belt 23
Is functioning as an image receiver.

In this developing device 1, in the housing 11,
The toner T as a developer is stored, and the developing roller 12, the supply roller 13, and the regulation blade 14 are housed. The developing roller 12 carries charged toner (that is, charged particles for image formation) T, and rotates at a predetermined peripheral speed in the direction of arrow D in FIG. Flight start position) J
It is a toner carrier to be transported to. This developing roller 12
Is formed in a cylindrical shape with a metal or alloy such as aluminum or iron, and a DC voltage is applied from the developing roller bias generator 103 provided in the engine controller 102.

The supply roller 13 is brought into contact with the outer peripheral surface of the developing roller 12 and rotates in the opposite direction to the developing roller 12,
The toner T is supplied to the developing roller 12 and the excess toner T is dropped from the developing roller 12. The supply roller 13 is made of, for example, a metal core wrapped with synthetic rubber such as urethane sponge, and also has a function of charging the toner T to a predetermined polarity by frictionally contacting the developing roller 12. In the present embodiment, the toner T will be described below as being negatively charged.

The regulating blade 14 is applied to the outer peripheral surface of the developing roller 12 on the downstream side of the supply roller 13 in the rotation direction D of the developing roller 12, and negatively charges the toner T by friction with the developing roller 12. The amount of toner T carried on the developing roller 12 is regulated. More specifically, the regulation blade 14 is constituted by a plate-shaped metal piece 141 having one end fixed to the housing 11, and an elastic member 142 attached to the other end of the plate-shaped metal piece 141. Contact the surface, toner T
Are regulated.

The back electrode 3 is opposed to the developing roller 12.
Are arranged. More specifically, the back electrode 3 is shown in FIG.
As shown in FIG. 3, the intermediate transfer belt 23 is sandwiched between the developing roller 12 and the developing roller 12. The back bias generator 104 provided in the engine controller 102
Therefore, a DC voltage higher than the voltage applied to the developing roller 12 is applied, and a transfer electrostatic field for transferring the charged toner T toward the back electrode 3 is applied between the developing roller 12 and the back electrode 3. Has been formed. For this reason, the charged electrostatic toner T at the toner flying start position J is generated by the transfer electrostatic field.
Flies from the developing roller 12 toward the back electrode 3 and is deposited and attached to the surface of the intermediate transfer belt 23 that functions as an image receiver.

Further, in this embodiment, in order to control the flying of the charged toner T onto the intermediate transfer belt 23, a flexible printed circuit board (hereinafter referred to as FPC) 4 is provided between the developing roller 12 and the back electrode 3. It is arranged. Hereinafter, the configuration and operation of the FPC 4 will be described with reference to FIGS. 3 and 4.

FIG. 3 is a diagram showing a partially enlarged cross section of a flexible printed circuit board and a flying model of charged toner. Further, FIG. 4 is a view showing control electrodes and deflection electrodes formed on the flexible printed circuit board. This F
In the PC 4, a toner passage hole 41 for guiding the charged toner T from the developing roller 12 to the back electrode 3 is formed in a base 42 made of an electrically insulating material such as polyimide.
Although only one toner passage hole 41 is shown in FIG. 3, in this embodiment, a plurality of toner passage holes 41 are provided in a line in the direction perpendicular to the plane of FIG. The charged toner T can pass through the toner passage holes 41 toward the back electrode 3 side. Although the toner passage holes 41 are arranged in one row in this embodiment, they may be arranged in plural rows. Further, the shape of the toner passage hole 41 may be circular as in this embodiment, or may be elliptical or polygonal.

On the side of the developing roller 12 of the base 42, a control electrode 43 is formed in a ring shape so as to surround each toner passage hole 41. In addition, each control electrode 43
The lead wire 44 extends in the direction orthogonal to the arrangement direction of the toner passage holes 41. The shape of the control electrode 43 is not limited to the circular shape, but may be any shape, and may be, for example, an elliptical shape or a polygonal shape. Further, the control electrode 43 may have a partial cutout instead of a perfect ring. .

On the side of the back electrode 3 of the base 42,
A pair of deflection electrodes 45L, 4L is provided for each toner passage hole 41.
As shown in FIG. 4, 5R is provided so as to be diagonally opposed to the conveyance direction Y of the intermediate transfer belt 23 (direction orthogonal to the toner passage hole array), and the deflection electrodes 45L, 4L,
Lead wires 46L and 46R are extended from 5R, respectively.

Although not shown in FIGS. 3 and 4, the base body 42 includes a control bias generator 47 (FIG. 2) and an L deflection bias generator 48L (FIG. 2), which are high voltage driver ICs and the like. And R deflection bias generator 48
R (FIG. 2) is provided. Of these, the control bias generator 47 is electrically connected to each control electrode 43, and an appropriate voltage is selectively applied according to an opening / closing control signal from the CPU 105 of the engine controller 102, whereby the toner is discharged. The passage hole 41 is opened and closed electrostatically. That is, for each control electrode 43, the charged toner T is ejected from the developing roller 12, passes through the toner passage hole 41, and is ejected toward the back electrode 3, so that the toner is between the developing roller 12 and the back electrode 3. It exposes the transfer electrostatic field passing through the passage hole 41 and limits the exposure.

The L deflection bias generator 48L is electrically connected to the deflection electrode 45L, and the R deflection bias generator 48R is electrically connected to the deflection electrode 45R. The engine controller 102 controls the deflection. By appropriately applying an appropriate voltage to each of the deflection electrodes 45L and 45R according to the signal, the charged toner T
The flight direction of is switched to the following three directions.

(1) No deflection: When the same voltage is applied to both the deflection electrodes 45L and 45R of the arrow P1 in FIG. 3, the charged toner T has a toner passage hole 41 as shown by the arrow P1 in FIG. Straight through the intermediate transfer belt 23
And fly to a position corresponding to the toner passage hole 41 on the above.

(2) Leftward deflection: Among the deflection electrodes 45L and 45R indicated by the arrow P2 in FIG. 3, the deflection electrode 45L disposed on the left side of the toner passage hole 41 on the right side of the deflection electrode 45L on the right side of the intermediate transfer belt 23 as a reference. Deflection electrode 45 arranged
When a voltage relatively higher than R is applied, the charged toner T charged in the negative polarity has a static charge for deflection generated between the electrodes 45L and 45R as shown by an arrow P2 in FIG. It is deflected to the left by the electric field.

(3) Rightward deflection: Among the deflection electrodes 45L and 45R indicated by the arrow P3 in FIG. 3, the deflection electrode 45R disposed on the right side of the toner passage hole 41 on the left side with respect to the conveyance direction Y of the intermediate transfer belt 23 is on the left side. Deflection electrode 45 arranged
When a voltage relatively higher than L is applied, the charged toner T, which is negatively charged, is deflected statically between the electrodes 45L and 45R as shown by the arrow P3 in FIG. It is deflected to the right by the electric field.

As described above, in this embodiment, while changing the flying direction of the charged toner T to three directions, the charged toner T is landed on the intermediate transfer belt 23 at the landing position PI of the intermediate transfer belt 23 including the deflection range. I am letting you.

However, as described above, the deflection electrodes 45L, 45
Since R is diagonally opposed to the transport direction Y of the intermediary transfer belt 23, the intermediary transfer belt 23 is formed by the three modes of (1) no deflection, (2) left deflection, and (3) right deflection. When 23 is stopped, the intermediate transfer belt 23
On the intermediate transfer belt 23, three dots lined up obliquely with respect to the transport direction Y of. In this case, the transport speed is determined so that the intermediate transfer belt 23 is transported by the displacement amount (distance) of the adjacent dots in the cycle (time) of hitting the dots, so that the three dots are transferred to the intermediate transfer belt 23. They can be arranged linearly in the direction orthogonal to the transport direction Y. Therefore, three dots can be formed with one toner passage hole 41, and the density of the dots can be increased.

In the base 42 of the FPC 4, the developing roller 12
On the surface 421 on the side and the surface 422 on the side of the back electrode 3, a semiconductive layer 49 for antistatic is formed and a ground potential is given. These semi-conductive layers 4
Reference numeral 9 indicates an optimum resistance value at a preset temperature (initial setting temperature). The frictional charge generated when the charged toner T flying as described above comes into contact with the FPC 4 is indicated by the FPC 4
The FPC 4 can be effectively prevented from being discharged from the above, and the influence on the electrostatic transfer field and the deflection electric field can be suppressed. That is, good print quality can be ensured while the temperature of the semiconductive layer 49 is maintained within the initial set temperature or the allowable temperature range.

Further, between the FPC 4 and the developing roller 12 configured as described above, a spacer spread in the longitudinal direction of the developing roller 12 (the direction X perpendicular to the paper surface of FIG. 3), that is, in the width direction of the developing roller 12. 5 is inserted and a part of the spacer 5 comes into contact with the toner layer TL carried on the developing roller 12, whereby the gap GP between the developing roller 12 and the toner passage hole 41 of the FPC 4 is regulated to a constant value. ing. Thus, in this embodiment, the spacer 5 functions as a gap defining means. The structure and function of the spacer 5 will be described in detail later.

In the image forming apparatus constructed as described above, when an image signal is given from the external device to the main controller 101 of the control unit 100, the CPU 105 of the engine controller 102 responds to the signal from the main controller 101. The control signal corresponding to the image signal is supplied to the control bias generator 47 and the L deflection bias generator 4.
The toner T is applied to the 8L and R deflection bias generators 48R to fly and adhere to the intermediate transfer belt 23 to form a toner image corresponding to the image signal. Then, regarding the toner image, in the predetermined transfer region TR, the cassette 7
The image is transferred onto a sheet S such as a copy sheet, a transfer sheet, and an OHP transparent sheet taken out from the sheet. Further, the sheet S on which the image is thus formed is conveyed to the discharge tray (not shown) via the fixing unit 8.

Next, the structure and function of the spacer 5 will be described in detail. FIG. 5 is an exploded perspective view showing the arrangement of the spacer 5, the developing roller 12, and the FPC 4 in the developing device 1. FIG. 6 is a cross-sectional view showing these contact states. Note that in the following, for ease of understanding, three toner passage holes 41 among the plurality of toner passage holes 41 arranged in the width direction X orthogonal to the transport direction D of the toner T are arranged.
However, in an actual apparatus, a larger number of toner passage holes 41 are arranged in a row to form a toner passage hole row. For example, in an image forming apparatus that forms 3 dots for each toner passage hole as shown in FIG. 3, an image corresponding to the width (210 mm) of Japanese Industrial Standard A4 size paper with a resolution of about 600 dpi (dots / inch) is displayed. In order to enable the formation, about 1600 toner passage holes are formed in the X direction at a pitch of about 130 μm.

In the spacer 5 of this image forming apparatus, as shown in FIG.
As shown in FIG. 5, a slot 51 having a rectangular opening whose long side extends along the Y direction is provided corresponding to each toner passage hole 41 of the FPC 4. Then, when the spacer 5 is superposed on a predetermined position on the FPC 4, the opening end of each toner passage hole 41 and the surface area of the FPC 4 adjacent to the upstream side and the downstream side thereof are exposed to the developing roller 12 side through each slot 51. . Of the surface area of the FPC 4 exposed to the developing roller 12 side through the slot 51, the area located on the upstream side of the toner passage hole 41 corresponds to the adjacent area of the present invention. Further, the toner layer TL is carried on the surface of the cylindrical developing roller 12, and the FPC 4 and the spacer 5 which are superposed as described above are integrally pressed against the toner layer TL, so that the toner layer TL and the toner layer TL are formed. The surface of the spacer 5 on the side of the developing roller 12 is
Abutting in a contact area CR having a constant width d outside the slots 51 located at both ends of the extended portions extending in the Y direction between the slots 51 to separate the slots or in the arrangement of the slots. Become.

As shown in FIG. 6A, this contact area C
In R, the toner particles T1 forming the toner layer TL are sandwiched between the developing roller 12 and the spacer 5 and subjected to pressure, while in the hole facing region FR facing the opening end of the toner passage hole 41, the slot 51 is formed. The toner particles T2 are not in contact with the spacer 5 due to the opening due to. Further, as shown in FIG. 6B, the slot 51 extends beyond the width d of the contact region CR to the upstream side and the downstream side thereof, whereby the hole facing region is rotated as the developing roller 12 rotates. The toner T2 conveyed from the upstream side of FR is
It passes through this region FR without touching the spacer 5.

A more detailed description will be given with reference to FIG.
FIG. 7A is a cross-sectional view as seen from the AA cross section shown in FIG. 6A, and FIG. 7B is BB shown in FIG. 6A.
It is sectional drawing seen from the cut surface. As shown in FIG. 7A, the toner T1 carried on the upstream side of the contact area CR on the developing roller 12 is the direction D of the developing roller 12 in the arrow direction.
To the contact area C while contacting the spacer 5 by rotating
Pass R. Thus, the toner layer TL and the spacer 5
The contact between the developing roller 12 and the FPC 4
The distance GP between and is held to the extent that the thickness of the spacer 5 and the toner particle size are added.

On the other hand, as shown in FIG.
A slot 51 is provided in the hole facing region FR to form a space between the toner layer TL and the FPC 4, and the toner particles T2 forming the toner layer TL reach the hole facing region FR without contacting the spacer 5. To do. The hole facing region FR is located at a position facing the back electrode 3 through the toner passage hole 41, and when a transfer electrostatic field is formed by applying a control signal to each electrode, the toner T carried in this region FR is formed.
2 will fly toward the back electrode 3. Therefore, in this embodiment, the hole facing region FR is the toner flying start position J.

As described above, in this embodiment, the toner layer TL and the spacer 5 are brought into contact with each other at the contact position CR which is close to each toner passage hole 41.
The gap GP with the PC 4 can be held accurately and stably. Further, by providing the spacers 5 with the slots 51 corresponding to the respective toner passage holes 41 of the FPC 4, the toner T2 in the hole facing area FR and the area located upstream thereof in the toner layer TL carried on the developing roller 12 is provided. With respect to, the toner can be conveyed to the toner flying start position J without making contact with the spacer 5. Therefore, a uniform and stable toner layer is always conveyed to the toner flying start position J, and as a result, this image forming apparatus can form a stable toner image with good image quality. There is.

The present invention is not limited to the above embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, the shape and size of the slot 51 provided in the spacer 5 are not limited to the above, and various other shapes can be used. FIG. 8 is a diagram illustrating another embodiment of the spacer of the image forming apparatus according to the present invention. For example, in the above-described embodiment (FIG. 6B), the spacer 5 is provided with the slot 51 having a rectangular opening extending beyond the width d of the contact region CR and extending to the upstream side and the downstream side thereof. The shape of the opening is not limited to the rectangle as described above, and may have another shape such as an ellipse or a polygon.

Further, each slot does not necessarily have a contact area CR.
It does not need to extend further to the downstream side, as long as it includes at least the toner passage hole 41 and extends to the upstream side of the upstream end of the contact region CR. Therefore, for example, like the spacer 5a shown in FIG. 8A, the slot 51 may be formed so as to expose only the toner passage hole 41 and the adjacent region on the upstream side thereof.

Further, like the spacer 5b shown in FIG. 8B, a comb tooth-shaped slot 52 for exposing the toner passage hole 41 and the adjacent region on the upstream side thereof may be provided. Like the spacer 5c shown in FIG. 8 (c), a slot 53 that collectively exposes the plurality of toner passage holes 41 and their adjacent regions located on the upstream side may be provided. In this spacer 5c, the toner layer TL on the developing roller 12 comes into contact with the spacer 5 only in the contact region CR outside the opening of the slot 53 in the X direction. Therefore, in the spacer 5c, the slot 53 corresponds to the opening of the present invention.

In the above embodiment, the FPC 4 is provided with one row of toner passage holes composed of a plurality of toner passage holes 41 arranged in the width direction X, but two or more rows are provided. The present invention can also be applied to an apparatus having a toner passage hole array. FIG. 9 is a diagram illustrating the shape of a spacer in an image forming apparatus having two rows of toner passage holes. In this device, FPC4
Two rows of toner passage holes, each of which is composed of a plurality of toner passage holes 41a and 41b arranged in parallel along the width direction X, are provided on the upper side. In such a device, the spacers 5 may be provided with slots so that the toner passage holes 41a and 41b are exposed to the developing roller 12 side in the toner passage holes and the adjacent region on the upstream side thereof. For example, as shown in FIG. 9A, each toner passage hole 41
Slots 51a and 51b may be provided so that the toner passage holes 41a and 41b and adjacent regions located on the upstream side of the toner passage holes 41a and 41b are exposed, and the shapes of the slots 51a and 51b are Figure 9 (b)
All may be the same as shown in FIG.

Further, as shown in FIG. 9C or 9D, a slot 54 or 55 that collectively includes a plurality of toner passage holes 41a and 41b and their adjacent regions may be provided.

Further, for example, in the above embodiment, after the toner image is formed on the transfer medium such as the intermediate transfer belt 23,
The present invention is applied to an intermediate transfer type image forming apparatus that transfers the toner image on the transfer medium to the sheet S. However, the charged toner T flying from the developing device 1 is directly landed on the sheet S to form an image. The present invention may be applied to an image forming apparatus to be formed.

In the above embodiment, the semiconductive layer 49 is used.
The present invention is applied to an image forming apparatus in which the FPC 4 is provided with antistatic property, but the application target of the present invention is not limited to this, and an antistatic semiconductive layer is provided. The present invention can be applied to an image forming apparatus which is not provided.

Further, in the above embodiment, the deflection electrode 45 is used.
The flying directions of the charged toner T are three directions P by L and 45R.
Although the present invention is applied to an image forming apparatus that can switch between 1, P2, and P3, the application target of the present invention is not limited to this, and an image in which the flight direction of the charged toner T is fixed is used. The present invention can be applied to a forming apparatus.

In the above embodiment, the spacer 5 is brought into contact with the semiconductive layer 49 so that the spacer 5 is prevented from being charged and the electric field near the toner passage hole 41 is not disturbed. Although it is applied, another bias potential may be applied if necessary.

Further, in the above-described embodiment, the present invention is applied to an image forming apparatus which forms an image with one developing device 1, that is, which executes so-called monochromatic printing. However, in the case of forming a full-color image, for example. In contrast to a so-called tandem type color image forming apparatus in which the same developing devices 1 for four types of toners of yellow, magenta, cyan and black are arranged in a line in the conveyance direction Y of the intermediate transfer belt 23 or the sheet S, However, the present invention can be applied.

[0049]

As described above, according to the present invention, since the gap defining means is in contact with the toner layer on the toner carrier, the gap between the toner layer and the toner flying control means is kept constant. ing. Then, among the toners forming the toner layer sent to the toner flying start position, at least the toner carried in the hole facing area facing the opening end of the toner passing hole of the toner flying control means is allowed to fly without touching the gap defining means. It is transported to the starting position. Therefore, the uniformity of the toner layer is not impaired due to the toner being scraped off or the charge amount being changed, and the toner flying from the toner carrier to the back electrode can be controlled with stability. It is possible to stably form a toner image with good image quality.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a block diagram showing an electrical configuration of the image forming apparatus of FIG.

FIG. 3 is a diagram showing a partially enlarged cross section of a flexible printed circuit board and a flying model of charged toner.

FIG. 4 is a diagram showing control electrodes and deflection electrodes formed on a flexible printed circuit board.

FIG. 5: Spacer, developing roller and FP in the developing device
It is an exploded perspective view showing arrangement of C.

FIG. 6 is a spacer, a developing roller and an FP in the developing device.
It is sectional drawing which shows the contact state of C.

7A is a cross-sectional view taken along the line AA shown in FIG. 6A, and FIG. 7B is a sectional view taken along line B of FIG. 6A.
FIG. 6B is a cross-sectional view seen from a section B.

FIG. 8 is a diagram illustrating another embodiment of the spacer of the image forming apparatus according to the present invention.

FIG. 9 is a diagram illustrating a shape of a spacer in an image forming apparatus having two rows of toner passage holes.

[Explanation of symbols]

1 ... Developer 3 ... Back electrode 4 ... FPC (toner flying control means) 5 ... Spacer (gap defining means) 12 ... Developing roller (toner carrier) 41, 41a, 41b ... Toner passage holes 51, 51a, 51b ... Slot (slot portion) 53, 54, 55 ... Slot (opening) FR: Hole facing area T ... toner TL ... toner layer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shinichi Kamoshida             Seiko, 3-3-3 Yamato, Suwa City, Nagano Prefecture             -In Epson Corporation F-term (reference) 2C162 AE04 AE25 AE31 AE47 AE56                       AE58 AE74 CA03 CA12 CA24                 2H029 DB00

Claims (4)

[Claims] 1. A toner carrier which carries a charged toner and moves the toner in a predetermined moving direction to a toner flying start position, and a toner carrier facing the toner flying start position of the toner carrier. A rear electrode disposed in such a manner that a toner passage hole is formed, and the rear electrode is disposed between the toner carrier and the rear electrode and passes through the toner passage hole from the toner carrier. A toner flying control means for forming a toner image by landing toner on an image receiving body conveyed between the back electrode and the toner by controlling the toner flying toward the back electrode, and a toner layer carried on the toner carrying body. And a gap defining means for defining a gap between the toner carrier and the toner flying control means in contact with the toner carrier, and the toner flying start position of the toner layer. In the above, the toner carried in the hole facing area of the toner passage hole facing the opening end on the toner carrier side is conveyed to the toner flying start position without contacting the gap defining means. An image forming apparatus characterized by. 2. The gap defining means includes, on the toner carrier side opening end of the toner flying control means and on the toner carrier side surface of the toner flying control means, on the upstream side of the opening end in the moving direction. The image forming apparatus according to claim 1, further comprising a slot portion that exposes the adjacent area located on the toner carrier side. 3. The toner flight control means is provided with at least one row of toner passage holes formed by arranging a plurality of the toner passage holes in a width direction orthogonal to the moving direction, and the gap defining means is provided. Is provided with an extending portion extending in the moving direction between each slot portion provided corresponding to each of the plurality of toner passage holes, and the toner layer is provided with the extending portion of the gap defining means. The image forming apparatus according to claim 2, wherein the image forming apparatus is in contact with the portion. 4. The toner flight control means is provided with a plurality of toner passage holes, and the gap defining means has a plurality of toner passage holes of a surface of the toner flight control means on the toner carrier side. The open end,
An opening is provided to expose a surface area including an adjacent area located on the upstream side of the opening end in the moving direction to the toner carrier side, and the toner layer has a width perpendicular to the moving direction. The image forming apparatus according to claim 1, wherein the image forming apparatus is in contact with the gap defining means outside both ends of the opening in the direction.