JP2003170621A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably form toner images with a good image quality in an imaging apparatus which specifies a gap between a toner carrier and a toner fly control means by butting a gap-specifying means against a toner layer on the toner carrier. <P>SOLUTION: A regulating blade 14 for regulating a toner T carried by a developing roller 12 is butted against the toner layer TL by an angle θ1≠90°. On the other hand, a spacer 5 for specifying the gap GP is butted against the toner layer TL by an angle θ2 smaller than the angle θ1. Accordingly, the toner T is less scraped off by the spacer 5 when the toner constituting the toner layer TL comes in contact with the spacer 5, so that the uniform toner layer TL can be supplied to a toner fly start position J. <P>COPYRIGHT: (C)2003,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 or a printer, and more particularly to copying paper, transfer paper, copying paper, 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. In this manner, the toner flying is controlled by the flexible printed circuit board, that is, the board functions as the toner flying control means, so that the 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, the spacer is arranged so as to come into contact with the toner layer carried on the toner carrier between the toner regulation blade and the toner flying start position, whereby the gap between the toner carrier and the toner flying control means is provided. Is prescribed.

[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. 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.

For example, a part of the toner layer regulated to a predetermined thickness by the toner regulation blade is scraped off by the contact with the spacer, and as a result, the toner that should fly at the toner flying start position falls off and the toner drops. There is a problem that a part of the image is lost or the gap fluctuates as the thickness of the toner layer changes and the image quality deteriorates.
Further, if the peeled toner scatters inside the apparatus, it may stain the inside of the apparatus and the image receiver.

The present invention has been made in view of the above problems, and an image forming process 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.

[0009]

In order to achieve the above-mentioned object, an image forming apparatus according to the present invention is a toner which carries a back electrode and a toner and moves in a predetermined moving direction to face the back electrode. A toner carrier that conveys the toner to a flying start position; a toner regulating unit that regulates the toner carried on the toner carrier on the upstream side in the moving direction with respect to the toner flying start position; and the back electrode. The toner is transferred to the image receiving body, which is arranged between the back surface electrode and the back surface electrode by controlling the flight of the toner from the toner flying start position of the toner carrier to the back surface electrode. The toner flight control means for landing the toner image to form a toner image, and the toner flight start position and the toner regulation means in the moving direction are supported on the toner carrier. The toner carrier and the toner flying control means, the gap defining means for defining a gap between the toner carrying body and the toner flying control means is provided, and further, in a portion where the toner carrying body and the toner regulating means come into contact with each other, In the first contact portion, which is the most upstream side end in the moving direction, the surface of the toner carrier and the toner regulating means sandwiching the first contact portion when viewed from the upstream side in the moving direction. A first corner formed by the two surfaces with respect to the end surface is a second contact portion that is an end portion on the most upstream side in the moving direction in a portion where the toner layer and the gap defining unit contact each other. It is equal to or larger than the second angle formed by the two surfaces of the surface of the toner layer and the end surface of the gap defining means sandwiching the second contact portion when viewed from the upstream side in the moving direction. Feature .

Hereinafter, in the present specification, among the portions where the toner carrier or the toner layer formed thereon and the respective members come into contact with each other, the most upstream side end in the moving direction of the toner carrier is referred to as "contact.""Contactportion", when viewed from the upstream side in the moving direction with respect to the contact portion, an angle formed between the surface of the toner carrier or the surface of the toner layer formed thereon and the end surface of each member is "contact". "Corner".

In the invention thus constituted, the toner regulating means, which is disposed in proximity to the toner carrier at the predetermined contact angle (first angle) at the first contact portion, adheres to the toner carrier. The toner layer having a predetermined thickness is formed on the surface of the toner carrier by scraping off a portion of the toner that exceeds a preset thickness. The toner layer is conveyed to the downstream side with the movement of the toner carrier and contacts the gap defining means. The contact angle between the gap defining means and the toner layer, that is, the second angle is It is set to be equal to or smaller than the contact angle of the toner regulating means.

Here, it is considered that the effect of scraping the toner by the member contacting the toner layer is higher as the contact angle is larger. That is, the toner remaining on the toner carrier without being scraped off by the friction with the toner regulating means contacting at a larger contact angle is scraped off by the gap defining means contacting at a smaller contact angle. The probability of being affected is considered to be low. As described above, the scraping of the toner layer by the gap defining means is suppressed, and the toner loss and the gap variation are small, so that it is possible to stably form a toner image without deterioration of image quality. There is.

By the way, when the contact angle of the member contacting the toner layer exceeds 90 degrees, that is, when it is an obtuse angle, the end face of this member is applied to the toner layer in the direction opposite to the moving direction of the toner layer. Therefore, the effect of scraping the toner is further enhanced. From this, the second corner is
It is preferably 90 degrees or less. With this configuration, the direction of contact of the gap defining means with the toner layer is along the moving direction of the toner layer, so that scraping of the toner by the gap defining means is further suppressed, and good image quality is achieved. Image formation can be performed.

Further, since the contact angle of the gap defining means with respect to the toner layer satisfies the above condition, the surface of the toner layer and the end surface of the gap defining means which are in contact with each other at the second contact portion are separated from each other. The contact planes of the second contact portions may be shared. By doing so, the surface of the toner layer and the end surface of the gap defining means come into contact with each other at the second contact portion, and the contact angle between them becomes substantially zero, so that the toner scraping by the gap defining means is performed. Can be suppressed to the minimum and image formation with good quality can be performed.

The image forming apparatus according to the present invention is
In order to achieve the above object, a back electrode, and a toner carrier that carries a toner that is positively charged and moves in a predetermined moving direction to convey the toner to a toner flying start position facing the back electrode. A toner regulating means for regulating the toner carried on the toner carrier on the upstream side in the moving direction with respect to the toner flying start position, and the toner carrier arranged between the back electrode and the toner carrier. Toner flight control means for forming a toner image by landing toner on an image receiving body conveyed between the back electrode and the back electrode by controlling the flight of toner from the toner flying start position of the body to the back electrode, Between the toner flying start position and the toner regulating means in the moving direction, the toner layer is brought into contact with the toner layer carried on the toner carrying body and the toner carrying body. And a gap defining means for defining a gap between the toner flight control means, moreover, the potential of the toner regulating means, is characterized in the same or lower than this the potential of said gap defining means.

In the invention thus constituted, the probability that the toner carried on the toner carrier moves to the gap defining means is kept low. The reason is as follows. That is, when each toner particle is rubbed between the toner regulating means and the toner carrier, the toner particles having high adhesiveness (easy adhesion) to the toner carrier remain on the toner carrier, but otherwise. Toner particles are scraped off the surface of the toner carrier by the toner regulating means, and as a result,
The thickness of the toner layer on the toner carrier is regulated to be constant. In other words, among these toner particles, only the particles having a higher adhesiveness to the toner carrying member than the toner regulating member are attached to the surface of the toner carrying member and transported to the downstream side of the toner regulating member. Become.

The toner layer carried on the toner carrying member and conveyed to the downstream side in this manner then comes into contact with the gap defining means arranged between the toner flying start position and the toner regulating means. At this time, the gap defining means has the same potential as the toner regulating means or a potential higher than that. For positively charged toner, the higher the potential of the object, the weaker the electrostatic attraction and the more difficult it is to adhere to the object.Therefore, the adhesion of the toner to the gap defining means is the same as the adhesion to the toner regulating means. Degree or lower. Therefore, when the toner particles are rubbed between the toner carrying member and the toner regulating unit, the toner particles adhered to the toner carrying member instead of the toner regulating unit and conveyed have lower adhesiveness than the toner regulating unit (or to the same extent). The probability of moving to the gap defining means is low.

As described above, in the image forming apparatus according to the present invention, the toner layer carried on the toner carrier is conveyed to the toner flying start position without being scraped by the contact with the gap defining means. It is possible to stably form a toner image without deterioration of image quality.

Further, in order to hold the toner on the toner carrier more reliably, it is desirable that the adhesion between the toner carrier and the positively charged toner is the highest in the toner carrier, so at least the toner carrier is It is desirable that the potential is the same as that of the toner regulating means, more preferably lower than that of the toner regulating means.

Further, when the charging polarity of the toner is the negative polarity opposite to the above, the magnitude relation of the potential of the gap defining means, the toner regulating means and, if necessary, the toner carrier is opposite to the above. You can do it like this. That is, by setting the toner regulating means to have the same potential as the gap regulating means or a potential higher than that, it is possible to prevent the negatively charged toner from migrating to the gap regulating means, and the toner carrier also regulates the toner. By setting the potential to be equal to or higher than that of the means, it becomes possible to more reliably hold the toner on the toner carrier.

[0021]

1 is a diagram showing a first embodiment of an image forming apparatus according to the present invention. 2 is shown in FIG.
3 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 engine controller 102 is responsive to the signal from the main controller 101.
Controls each part of the developing device 1 so that the two rollers 2
Toner is ejected to and adheres to the intermediate transfer belt 23 that is stretched around the first and second toner particles 22 to form a toner image corresponding to the image signal. Thus, in this embodiment, the intermediate transfer belt 2
3 functions 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 a charged toner (that is, charged particles for image formation) T, and rotates at a predetermined peripheral speed in a direction D of an arrow in FIG. 1 to face a rear electrode 3 described later (toner). 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 regulation 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 the toner T is negatively charged 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.

In this embodiment, a flexible printed circuit board (hereinafter referred to as FPC) 4 is provided between the developing roller 12 and the back electrode 3 in order to control the flight of the charged toner T onto the intermediate transfer belt 23. 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 developing roller 12 side of the substrate 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 back electrode 3 side of the base body 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 composed of a high voltage driver IC or 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 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) Left 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 arranged on the left 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 of the deflection electrode 45R disposed on the right side of the conveyance direction Y of the intermediate transfer belt 23 is a reference. 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, on the upstream side of the toner flying start position J in the rotation direction D of the developing roller 12, between the FPC 4 and the developing roller 12 configured as described above, the longitudinal direction of the developing roller 12 (see the plane of FIG. 3). The spacer 5 spread over the entire length of the spacer 5 is inserted to the front side of the toner passage hole 41 of the FPC 4.
Since a part of the toner comes into contact with the toner layer TL carried on the developing roller 12, the gap GP between the developing roller 12 and the toner passing hole 41 of the FPC 4 is regulated to a constant value.
Thus, in this embodiment, the spacer 5 functions as a gap defining means.

In the image forming apparatus configured 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. Applies a control signal corresponding to the image signal to the control bias generation unit 47, the L deflection bias generation unit 48L and the R deflection bias generation unit 48R to cause the toner T to fly and adhere onto the intermediate transfer belt 23 to correspond to the image signal. The formed toner image is formed. Then, the toner image is transferred onto a sheet S such as a copy sheet, a transfer sheet, and an OHP transparent sheet taken out from the cassette 7 in a predetermined transfer region TR. 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 regulating blade 14 and the spacer 5
The state of the contact portion between the toner layer TL and the developing roller 12 will be described in more detail with reference to FIG. Figure 5
FIG. 3 is an enlarged view of the periphery of the developing roller 12 in the image forming apparatus of FIG.

As described above, the elastic member 142 constituting the regulating blade 14 for regulating the thickness of the toner layer TL carried on the developing roller 12 is arranged close to the outer peripheral surface of the cylindrical developing roller 12. There is this elastic member 1
Since 42 is elastically deformed by being pressed against the toner layer TL on the developing roller 12, the elastic member 142 and the toner layer TL are in contact with each other over the area Z as shown in FIG. Of these, the position A1 that abuts the most upstream side end portion in the rotation direction of the developing roller 12 corresponds to the “first contact portion” according to the present invention. In FIG. 5, the area Z
Is shown as a part of an arc and the first contact portion A1 is shown as a dot, but in an actual device, the developing roller 12 and the elastic member 142 extend in the direction perpendicular to the plane of FIG. Needless to say, Z is a part of the cylindrical surface, and the first contact portion A1 is a straight line.

Here, of the end faces of the elastic member 142,
The end surface F1 located on the upstream side in the moving direction D of the developing roller 12 is located at the first contact portion A1 and is in contact with the toner layer TL, but as shown in FIG. The member 142 is arranged such that the end face F1 is substantially orthogonal to the surface of the developing roller 12. Therefore, the angle θ1 formed by the two surfaces sandwiching the contact portion A1, that is, the upstream end surface F1 of the elastic member 142 and the surface of the developing roller 12 is approximately 90 degrees. In this embodiment, this angle θ1 corresponds to the “first corner” in the present invention.

On the other hand, the spacer 5 is provided on the downstream side of the regulating blade 14 in the moving direction D of the developing roller 12, and at the position A2 shown in FIG.
2 is in contact with the toner layer TL above. In this embodiment, the position A2 corresponds to the "second contact portion" of the present invention.
When viewed from the upstream side in the moving direction D of the developing roller 12, two surfaces sandwiching the contact portion A2, that is, an angle θ2 formed by the upper surface F2 of the spacer 5 and the toner layer TL shown in FIG. 5 is an acute angle. In this embodiment, this angle θ2 corresponds to the "second corner" in the present invention.

As described above, the contact angle θ1 of the regulating blade 14 with the toner layer TL is approximately 90 degrees, while the contact angle θ2 of the spacer 5 with the toner layer TL is an acute angle smaller than this. The image forming apparatus according to the embodiment has the following operational effects. That is, the toner T carried on the developing roller 12 by friction with the supply roller 13
Among them, the toner T carried on the developing roller 12 beyond a predetermined thickness is scraped off from the developing roller 12 by coming into contact with the upstream end face F1 of the regulating blade 14 which is substantially orthogonal to the moving direction D thereof. As a result, the toner layer TL on the developing roller 12 is always regulated to have a constant thickness.

The toner layer TL thus regulated to have a constant thickness is conveyed to the downstream side as the developing roller 12 moves, and comes into contact with the spacer 5 at the second contact portion A2. In this case, the toner T that forms the toner layer TL enters the contact portion A2 with the spacer 5 at an angle θ2 that is shallower than the contact with the regulation blade 14 described above, and this contact causes the developing roller. The probability that toner T will be scraped off from 12 is low. for that reason,
The toner layer TL can reach the toner flying start position J without impairing its uniformity, and in combination with the effect of holding the gap GP by the spacer 5, it is possible to stably form a toner image with good image quality. Is possible.

Next, a second embodiment of the image forming apparatus according to the present invention will be described with reference to FIG. Figure 6
FIG. 3 is a diagram showing a second embodiment of the image forming apparatus according to the present invention. This embodiment is different from the first embodiment in that the relative electric potentials of the regulating blade 14 and the spacer 5 are clearly defined. That is,
The plate-shaped metal piece 141 that constitutes the regulation blade 14 is electrically connected to the developing roller bias generator 103 that outputs a DC voltage to the developing roller 12, and is given the same potential as the developing roller 12, while the spacer 5 is used. Is electrically grounded. Since the other configurations are the same as those in the first embodiment, the same reference numerals are given to the same configurations and the description thereof will be omitted.

In this embodiment, the developing roller 12, the regulating blade 14 and the spacer 5 are configured as described above.
Of the toner layer T
The scraping of the toner T at the contact portion A2 between the L and the spacer 5 is prevented. The reason why the scraping of the toner T can be prevented by such a configuration will be described below.

In this embodiment, a positive DC voltage is applied to the developing roller 12 from the developing roller bias generator 103. Therefore, an attractive force due to the Coulomb force acts between the toner T negatively charged by the frictional contact with the supply roller 13 and the developing roller 12, whereby the toner T adheres to the surface of the developing roller 12. Then, the toner T is conveyed to the contact portion A1 with the elastic member 142 forming the regulation blade 14 as the developing roller 12 rotates in the direction D.

Of the toner T that has reached the contact portion A1, the toner T, which has a relatively large amount of charge and is strongly attracted by the developing roller 12, is conveyed to the downstream side while being attached to the developing roller 12. The other toner is scraped off by the elastic member 142 and stays in the housing 11. In this way, the toner layer TL on the developing roller 12 is such that the variation in the charge amount of each toner particle forming the toner layer TL is reduced and the thickness thereof is regulated.

At this time, since the developing roller bias generator 103 applies the same potential as the developing roller 12 to the plate-shaped metal piece 141 of the regulating blade 14,
The developing roller 12 and the elastic member 142 have the same potential. Therefore, even if an object having the same potential as or lower than the elastic member 142 is brought into contact with the toner particles T remaining on the developing roller 12 without being peeled off by frictional contact with the elastic member 142, the Coulomb force causes It is clear that the toner T cannot be peeled off, and in order to peel it off, a larger Coulomb attractive force can be exerted on the toner T, that is, a higher potential object must be brought into contact with the toner T. Is.

Now, when the toner layer TL thus formed is further transported to the downstream side, the contact portion A with the spacer 5 is contacted.
Reach 2. Here, if the spacer 5 has a higher potential than that of the regulation blade 14, the toner T is carried on the developing roller 12 because the spacer 5 is more likely to adhere to the spacer 5 than the elastic member 142 in terms of static electricity. The toner T may move to the spacer 5 due to contact with the spacer 5.

On the other hand, in this embodiment, as shown in FIG. 6, the spacer 5 is electrically grounded, and therefore, the spacer 5 is relatively closer than the developing roller 12 and the elastic member 142 to which a positive potential is applied. Has a low potential. Therefore, as shown in the above discussion, the probability that the toner particles T forming the toner layer TL are peeled off by the Coulomb force acting between the toner particles T and the spacer 5 is low.

As described above, in this embodiment, the developing roller 12 and the regulating blade 14 are given the same positive potential, while the spacer 5 is given a lower ground potential. Therefore, even if the toner layer TL regulated by the regulation blade 14 comes into contact with the spacer 5, the toner layer TL is not scraped off and can reach the toner flying start position J while maintaining its uniformity, and as a result, the image quality is improved. It is possible to stably form a good toner image of.

In this embodiment, the developing roller 12
And the regulating blade 14 are set to a positive potential and the spacer 5 is set to the ground potential to prevent the scraping of the toner T by the spacer 5, but these potentials are not limited to the above, and the spacer 5 and the regulating blade 14 are not limited to the above. And the developing roller 12 regulates the respective potentials so that they have at least the same potential, or the higher potential in this order, thereby obtaining the effect of the present invention, that is, the effect of preventing the toner T from being scraped off by the spacer 5. Is something that can be done.

Therefore, all three of them may have the same electric potential, and the developing roller 12 may have a higher electric potential than the regulating blade 14. However, when the electric potential applied to the developing roller 12 becomes high, the developing roller 12 and the toner T are not in contact with each other. Since the attractive force between them becomes large and a high voltage must be applied to the control electrode 43, the back electrode 3 and the like in order to efficiently fly the toner T at the flying start position J, a too high voltage is applied to the developing roller 12. It is not realistic to apply.

Further, the developing roller 12 and the regulating blade 14 may be grounded to give a negative potential to the spacer 5, so that the spacer 5 and the regulating blade 14 have the same potential.
The developing roller 12 may have a higher potential than this. In short, as long as the potential relationship defined in the present invention is satisfied, these potentials may be set appropriately according to the specifications of the apparatus, the physical properties of the toner T, and the like.

The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the flat spacer 5 is provided and brought into contact with the toner layer TL at the contact portion A2. However, the shape of the spacer 5 is not limited to this, and for example, as illustrated in FIG. The wedge shape shown in FIG. 7A or the curved surface shape shown in FIG.

Among them, as shown in FIG. 7A, in the example in which the upper surface F3 of the spacer 51 has a wedge shape inclining toward the toner flying start position J, the inclined surface F3 has the toner layer TL. It is possible to make it coincide with the tangential plane at the position A21 on the cylindrical surface to be assembled. At this time, the spacer 5
The contact angle θ21 between 1 and the toner layer TL becomes almost zero, and the toner T forming the toner layer TL has such a shallow angle θ.
The spacer 5 enters the contact portion A21 at 21, and the spacer 5
It is possible to minimize the effect of scraping off the toner by 1. Further, the inclined surface F3 may be a curved surface having an upward convex curvature in FIG. 7, for example, other than such a flat surface.

Further, as shown in FIG. 7B, the spacer 5
In an example in which the upper surface F4 of No. 2 is a curved surface that matches the curvature of the toner layer TL, the area of the portion where the spacer 52 and the toner layer TL contact is large, and the force acting on the toner T due to the contact with the spacer 52 is increased. Since the toner T is dispersed, the toner T is less likely to come off. Also in this case, the spacer 52
By making the contact angle θ22 at the most upstream side end where the toner layer TL and the toner layer TL are in contact with each other, that is, the contact portion A22 as small as possible, the peeling of the toner T can be further suppressed.

Further, for example, in the above-described embodiment, the contact angle θ1 between the regulation blade 14 and the toner layer TL is approximately 9
Although it is set to 0 degree, it is not limited to this, and the contact angle θ1 may be an obtuse angle or an acute angle if necessary.
In any case, by setting the contact angle θ2 between the spacer 5 and the toner layer TL to be the contact angle θ1 or less, the toner scraping effect by the spacer 5 is less than the toner scraping effect by the regulation blade 14. And
Scraping of the toner by the spacer 5 can be suppressed. However, in order to prevent the scraping of the toner more effectively, it is desirable to make the contact angle θ2 as small as possible.

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.

Further, in the above embodiment, the semiconductive layer 49.
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.

Further, in the above-described embodiment, the present invention is applied to an image forming apparatus that forms an image with one developing device 1, that is, executes so-called monochromatic printing. However, for example, in the case of forming a full-color image, 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.

[0065]

As described above, according to the present invention, the toner regulating means arranged so as to come into contact with the toner layer at a predetermined angle is carried on the toner carrier at a predetermined thickness or more. While the toner is scraped off to regulate the thickness of the toner layer, the toner layer is configured to contact the gap defining means at an angle shallower than the above angle. Therefore, the toner is prevented from coming off due to the contact with the gap defining means, and the uniformity of the toner layer at the toner flying start position can be maintained and a toner image with good image quality can be stably formed.

According to the present invention, the magnitude relationship between these potentials is defined by taking into consideration the electrostatic adhesion of the toner to the toner regulating means, the gap defining means and, if necessary, the toner carrier. The probability that the toner carried on the toner carrier moves to the gap defining means is kept low. Therefore, the toner layer carried on the toner carrier is conveyed to the toner flying start position without being scraped by the contact with the gap defining means, and a toner image with stable image quality is stably formed. Is possible.

[Brief description of drawings]

FIG. 1 is a diagram showing a first 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.

5 is an enlarged view of the periphery of a developing roller in the image forming apparatus of FIG.

FIG. 6 is a diagram showing a second embodiment of an image forming apparatus according to the present invention.

FIG. 7 is a diagram showing another embodiment of the image forming apparatus according to the present invention.

[Explanation of symbols]

3 ... Back electrode 4 ... FPC 5 ... Spacer (gap defining means) 12 ... Developing roller (toner carrier) 14 ... Regulating blade (toner regulating means) 23 ... Intermediate transfer belt (image receptor) 41 ... Toner passage hole A1 ... First contact portion A2 ... second contact portion D ... Rotation direction (of the developing roller 12) F1 ... upstream end face of the regulating blade 14 F2 ... Upper surface of spacer 5 J: Toner flight start position T ... toner TL ... toner layer

Continued front page    F-term (reference) 2C162 AE25 AE31 AE55 AE74 AE84                       AE89 AF53 AF70 AJ23 CA03                       CA12 CA24                 2H029 DB04 DB05                 2H077 AC04 AD06 AD13 AD18 AD23                       AD35 BA08 CA11 FA22 GA13

Claims (7)

[Claims] 1. A back electrode, a toner carrier that carries toner while moving in a predetermined moving direction, and conveys the toner to a toner flying start position facing the back electrode, and a toner carrying member at the toner flying start position. On the other hand, a toner regulating means for regulating the toner carried on the toner carrier on the upstream side in the moving direction, and a toner regulating means arranged between the back electrode and the toner carrier to start the toner flying of the toner carrier. A toner fly control means for forming a toner image by landing toner on an image receiving body conveyed between the back electrode and the back electrode by controlling toner flight from a position to the back electrode; and the toner in the moving direction. Between the flying start position and the toner regulation means, the toner layer carried on the toner carrier is brought into contact with the toner carrier and the toner flying control means. A first contact portion, which is an end portion on the most upstream side in the moving direction, of a portion in which the toner carrier and the toner regulating means are in contact with each other, A first angle formed by the two surfaces of the surface of the toner carrier and the end surface of the toner regulating unit sandwiching the first contact portion when viewed from the upstream side in the moving direction is defined by the toner layer and the gap. The toner that sandwiches the second contact portion when viewed from the upstream side in the moving direction at the second contact portion that is the end portion on the most upstream side in the moving direction of the portion that contacts the regulating means. An image forming apparatus which is equal to or larger than a second angle formed by the two surfaces of the surface of the layer and the end surface of the gap defining means. 2. The image forming apparatus according to claim 1, wherein the second angle is 90 degrees or less. 3. A surface of the toner layer and an end surface of the gap defining means sandwiching the second contact portion when viewed from the upstream side in the moving direction, in the second contact portion. The image forming apparatus according to claim 1 or 2, wherein the tangent planes of the second contact portions are shared. 4. A back electrode, a toner carrier that carries a toner that is positively charged, and moves in a predetermined moving direction to convey the toner to a toner flying start position facing the back electrode, and the toner. A toner regulating unit that regulates the toner carried on the toner carrier on the upstream side in the moving direction with respect to the flying start position; and a toner regulating unit that is disposed between the back electrode and the toner carrier. A toner flying control means for forming a toner image by landing toner on an image receiving body conveyed between the toner and the back electrode by controlling the toner flying from the toner flying start position to the back electrode; In the direction between the toner flying start position and the toner regulating means, the toner layer carried on the toner carrier is abutted against the toner layer carried on the toner carrier. And a gap defining means for defining a gap between the control unit, moreover, the potential of the toner regulating means, the image forming apparatus, wherein the same or lower than this the potential of said gap defining means. 5. The image forming apparatus according to claim 4, wherein the potential of the toner carrier is equal to or lower than the potential of the toner regulating unit. 6. A back electrode, a toner carrier that carries a toner that is negatively charged, and moves in a predetermined moving direction to convey the toner to a toner flying start position facing the back electrode, and the toner. A toner regulating unit that regulates the toner carried on the toner carrier on the upstream side in the moving direction with respect to the flying start position; and a toner regulating unit that is disposed between the back electrode and the toner carrier. A toner flying control means for forming a toner image by landing toner on an image receiving body conveyed between the toner and the back electrode by controlling the toner flying from the toner flying start position to the back electrode; In the direction between the toner flying start position and the toner regulating means, the toner layer carried on the toner carrier is abutted against the toner layer carried on the toner carrier. And a gap defining means for defining a gap between the control unit, moreover, the potential of the toner regulating means, the image forming apparatus, wherein the same or higher than this the potential of said gap defining means. 7. The image forming apparatus according to claim 6, wherein the potential of the toner carrier is equal to or higher than the potential of the toner regulating unit.