JP2003107780A - Toner used for image forming device of toner jet system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide toners which are capable of forming images of good image quality by preventing the occurrence of clogging in pores for passage of the toners of an image forming device of a toner ink jet system. SOLUTION: The toners further added with an external additive of a titanium oxide at a content (x) satisfying the following equation 0<x<=1.5 wt.% in addition to base particles and an external additive of silica are used in the image forming device which forms the toner images corresponding to image signals by causing the flight and adhesion of the toners T electrostatically charged negative by the control signals meeting the image signals applied by a CPU of an engine controller to a control bias generating section, L deflection bias generating section and R deflection bias generating section according to the signals from a main controller.

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 a toner used in 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.

[0005]

However, in such a toner jet type image forming apparatus, since the toner flying from the toner carrier always passes through the toner passage hole, a part of the flying toner is flexible. When the toner adheres to the printed circuit board and the toner passage hole is clogged, the image density of the toner image formed on the image receiving body is lowered, and image defects such as printing failure occur.

The present invention has been made in view of the above problems, and in a toner jet type image forming apparatus, it is possible to prevent clogging of toner passage holes and form an image with good image quality. The purpose is to provide.

[0007]

SUMMARY OF THE INVENTION According to the present invention, a toner fly control means is provided between a toner carrying body carrying a toner and a back electrode, and the toner is carried through a toner passage hole provided in the toner fly control means. Of a toner jet method in which a toner image is formed by causing the toner to fly from the toner carrier toward the back electrode, and land the toner on an image receiving body conveyed between the toner flying control means and the back electrode. A toner used in a forming apparatus, which has mother particles, a silica external additive, and a titanium oxide external additive to achieve the above object, and wherein the titanium oxide content x is represented by the following formula: , 0 <x ≦ 1.5% by weight.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of various experiments and observations, the inventor of the present application found one of the main causes of clogging of toner passage holes in a conventional image forming apparatus. That is, in a conventional apparatus, a silica external additive is often added to the toner for the purpose of improving the fluidity and controlling the charge amount. When charged, the distribution of the charge amount of the toner is spread over a relatively wide range, and there are overcharged negatively charged toners and oppositely charged positively charged toners. In this way, the overcharged negatively charged toner has a stronger holding force of the toner on the toner carrier due to the image force acting on the toner carrier, which reduces the ease of flying the toner, that is, the lowering of the toner flying property. As a result, the image density and the image quality are deteriorated. For positively charged toner,
Under the influence of the electric field generated between the toner flying control means and the back electrode, the toner adheres to the end portion and the peripheral portion of the toner passage hole, causing clogging of the toner passage hole.

Therefore, in the present invention, by adding the titanium oxide external additive, the toner is prevented from being overcharged, the image force acting on the toner carrier is suppressed, and the toner flying property is improved. The image density and the image quality are improved by. Further, by adding an external additive of titanium oxide, the amount of toner of the opposite polarity is reduced to prevent clogging of toner passage holes. However, while the amount of the titanium oxide external additive is relatively small, the amount of the opposite polarity toner is smaller than that in the case where the titanium oxide external additive is not added, but when the amount added exceeds 1.5% by weight, On the contrary, the amount becomes larger than that when the titanium oxide external additive is not added. Therefore, in the present invention, the content x of the titanium oxide external additive is set within the range of 0 <x ≦ 1.5% by weight.

From the viewpoint of effectively suppressing the amount of toner charged to the opposite polarity and preventing clogging,
It is more preferable to set the content x of the titanium oxide external additive in the range of 0.2% by weight ≦ x ≦ 1.0% by weight.

In the toner jet type 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, for example, Japanese Patent No. 304529
As described in Japanese Patent Publication No. 5 and Japanese Patent Application Laid-Open No. 2000-211180, by disposing a spacer (gap defining means) on the upstream side in the moving direction with respect to the toner flying start position, the above gap is eliminated. A gap management technique that keeps it constant has been proposed. That is, the spacer is arranged so as to contact with the toner layer carried on the toner carrier between the toner regulating blade and the toner flying start position, whereby the gap between the toner carrier and the toner flying control means is provided. Is prescribed.

In the image forming apparatus constructed as above,
The toner layer regulated by the toner regulation blade always comes into contact with the spacer before being conveyed to the toner flying start position, and this contact increases the charge amount of the toner and causes so-called overcharging. It may be one of the main causes of image quality deterioration.

On the other hand, according to the present invention, by adding the titanium oxide external additive, it is possible to prevent the overcharge and effectively prevent the deterioration of the image quality. Therefore, the toner jet using the gap defining means is used. It can be said that it is suitable for the image forming apparatus of the method.

In the toner thus constructed, the toner flying control means is provided between the toner carrying body carrying the toner and the back electrode, and the first means is provided through the toner passage hole provided in the toner flying control means. Toner for forming a toner image by causing a toner charged with a polarity to fly from the toner carrier toward the back electrode and land on an image receiver conveyed between the toner fly control means and the back electrode. It can be suitably used for a jet type image forming apparatus. Hereinafter, a toner jet type image forming apparatus using the above toner will be described with reference to the drawings.

FIG. 1 is a diagram showing an example of an image forming apparatus in which the toner according to the present invention can be used. 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 engine controller 1 responds to the signal from the main controller 101.
By controlling each part of the developing device 1, the toner 02 flies and adheres to the intermediate transfer belt 23, which is wound around the two rollers 21 and 22, to form a toner image corresponding to the image signal. As described above, in this embodiment, the intermediate transfer belt 23 functions as an image receiving body.

In this developing device 1, in the housing 11,
The toner T according to the above-described invention is stored as a developer, 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. It is a toner carrier that is transported to a flight start position) J. The 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 generating unit 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.

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, a plurality of toner passage holes 41 are provided in a line at equal intervals in the vertical direction X of the paper surface of FIG. 3 in this embodiment. The charged toner T can pass through the toner passage holes 41 toward the back electrode 3 side. In this embodiment, the toner passage holes 41 are arranged in one line,
It may be arranged in a plurality of rows. Further, the toner passage hole 41
The shape may be circular as in this embodiment, or may be elliptical or polygonal.

Further, 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, 4 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 and 4L are provided.
Lead wires 46L and 46R are extended from 5R, respectively.

Although not shown in FIGS. 3 and 4, the substrate 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 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 is the 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 on the right side of the conveyance direction Y 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, which is negatively charged, as shown by 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 arranged on the right side of the toner passage hole 41 on the left side of the deflection electrode 45R arranged on the right side of the conveyance direction Y of the intermediate transfer belt 23 is used as a reference. Deflection electrode 45 arranged
When a voltage relatively higher than L is applied, the negatively charged toner T is charged by the static toner for deflection generated 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 FIG. 3). The spacer 5 spread over the entire length in the vertical direction X) is inserted in the front side of the toner passage hole 41 of the FPC 4 in the rotation direction D, and a part of the spacer 5 is carried on the developing roller 12 in the toner layer TL. By contacting with the developing roller 12 and the FP
The gap GP with the toner passage hole 41 of C4 is regulated to a constant value.

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. 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.

As described above, in the image forming apparatus shown in FIGS. 1 to 4, the toner according to the present invention, that is, the mother particles, the silica external additive, and the content x (0 <x ≦ 1.5 weight). %), The toner image is formed using the toner having the titanium oxide external additive, so that clogging of the toner passage hole 41 can be prevented and an image can be formed with good image quality.

The image forming apparatus in which the toner according to the present invention can be used is not limited to the above-mentioned apparatus but can be used in the apparatus configured as follows. That is, in the above embodiment, the semiconductive layer 4
The toner according to the present invention is used for the image forming apparatus in which the FPC 4 is provided with the anti-static property, but the present invention is also applied to the image forming apparatus in which the anti-static semi-conductive layer is not provided. The toner can be used.

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 toner according to the present invention is used for the image forming apparatus that can be switched to 1, P2 and P3, the toner according to the present invention is also used for the image forming apparatus in which the flight direction of the charged toner T is fixed. Can be used.

Further, in the above embodiment, the developing roller 12
A predetermined DC voltage is applied from the developing roller bias generator 103 to the above, but the toner according to the present invention is also used for an image forming apparatus configured to be grounded or to apply an AC voltage. be able to.

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

[0039]

EXAMPLES Next, examples of the present invention will be shown, but the present invention is not limited by the following examples, and may be carried out with appropriate modifications within a range compatible with the gist of the preceding and following description. Of course, it is possible, and all of them are included in the technical scope of the present invention.

Here, as the silica external additive to be added to the toner, 200 V (primary particle diameter: 12 n, manufactured by EROZIL) is used.
m) and OX50 manufactured by Nippon Aerosil Co., Ltd. (primary particle diameter: 4
0 nm) and titanium oxide ST manufactured by Titanium Industry Co., Ltd. as an external additive of titanium oxide added to the toner.
A toner was prepared by adding T-30S. Here, the addition amount of 200 V (primary particle diameter: 12 nm) manufactured by EROSIL and OX50 (primary particle size: 40 n) manufactured by Nippon Aerosil Co., Ltd.
m) and the amount added are both fixed at 0.5% by weight,
Titanium oxide external additive Titanium oxide S manufactured by Titanium Industry Co., Ltd.
The amount of TT-30S added was 0% by weight, 0.2% by weight,
Eight types of toner T (0) by changing to eight stages of 0.5% by weight, 1.0% by weight, 1.5% by weight, 2.0% by weight, 2.5% by weight, and 3.0% by weight. ), T (0.2), T (0.5), T
(1.0), T (1.5), T (2.0), T (2.5) and T (3.0) were prepared.

(Relationship between Titanium Oxide Addition Amount and Charge Amount Distribution) Here, the toners T (0) to T (3.0) are filled in the housing 11 of the developing device 1 and the toner carrier (developing in FIG. 1). The toner particle size and the toner charge amount of the toner collected from the roller 12) are measured by an Espert analyzer (E-SPART2;
Hosokawa Micron). For example, for toners T (0), T (0.5), T (1.0), and T (1.5), Espart Analyzer (E-SPART2; manufactured by Hosokawa Micron Corporation)
The charge amount distributions at the count of 3000 obtained by the above are as shown in FIGS. 5 to 8, respectively. It should be noted that the other toners T (2.0), T (2.5), and T (3.0) are not shown in the drawing for the measurement results (chart showing the charge amount distribution) by an Espert analyzer, but the same measurement as above is performed. went.

(Relationship Between Titanium Oxide Addition Amount and Charge Amount) Based on these results, the average charge amount for each addition amount was obtained, and the results shown in FIG. 9 were obtained.

(Relationship Between Titanium Oxide Addition Amount and Positively Charged Toner Amount) Further, when the positively charged toner amount (number%) for each addition amount was obtained based on the above measurement results, the results shown in FIG. 10 were obtained. . As is clear from the figure, the positively charged toner amount was changed by adding titanium oxide to the toner so that the titanium oxide content x satisfies the following equation: 0 <x ≦ 1.5 wt%. The amount of the positively charged toner in (1) (the amount of the positively charged toner of the toner T (0): the one-dot chain line in the figure) can be reduced. From the viewpoint of reducing the amount of positively charged toner and preventing clogging of the toner passage hole 41, the titanium oxide content x satisfies the following equation: 0.2 wt% ≤ x ≤ 1.0 wt% Thus, it is more preferable to add the titanium oxide external additive to the toner.

(Evaluation of Clogging) Toners T (0) to T (3.
Regarding whether or not clogging occurs when an image is formed using (0), whether white streaks are formed on the sheet S when “solid printing” is performed by the image forming apparatus of FIG. It was evaluated based on whether or not it was used. The results are shown in Table 1.

[Table 1]

(Effect of Over-Electrification of Titanium Oxide External Additive) The above-mentioned eight kinds of toner T (0) to T (3.0) are filled in the housing 11 of the developing device 1, and the developing roller 12 is axially (X). Direction), the surface potential of the toner layer TL before and after contact with the spacer 5 is measured by a surface potential meter (model number: MODEL344) manufactured by Trek Japan KK
The difference between both potentials was obtained. Then, it is integrated in the axial direction (X direction) of the developing roller 12 and each addition amount (0% by weight, 0.
2% by weight, 0.5% by weight, 1.0% by weight, 1.5% by weight, 2.0% by weight, 2.5% by weight, and 3.0% by weight) were determined. FIG. 11 is a graph summarizing the results.

[0046]

As described above, according to the present invention, in addition to the mother particles and the silica external additive, the titanium oxide external additive is contained at the content x satisfying the following formula: 0 <x ≦ 1.5% by weight. Is further added, the toner is prevented from being overcharged, the image force acting on the toner carrier is suppressed, the toner flying property is improved to improve the image quality, and the amount of toner charged to the opposite polarity is increased. It can be reduced at least as compared with the conventional example in which the titanium oxide external additive is not added, and clogging of the toner passage hole can be prevented.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an example of an image forming apparatus that can use toner according to the present invention.

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

3 is a diagram showing a partially enlarged cross section of a flexible printed circuit board used in the image forming apparatus of FIG. 1 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 is a graph showing a charge amount distribution of a toner to which no titanium oxide external additive is added.

FIG. 6 is a graph showing a charge amount distribution of a toner to which a titanium oxide external additive is added by 0.5% by weight.

FIG. 7 is a graph showing a charge amount distribution of a toner to which a titanium oxide external additive is added by 1.0% by weight.

FIG. 8 is a graph showing a charge amount distribution of a toner to which a titanium oxide external additive is added by 1.5% by weight.

FIG. 9 is a graph showing the relationship between the amount of titanium oxide added and the amount of charge.

FIG. 10 is a graph showing the relationship between the amount of titanium oxide added and the amount of positively charged toner.

FIG. 11 is a graph showing the relationship between the amount of titanium oxide added and the surface potential difference.

[Explanation of symbols]

3 ... Back electrode 4 ... FPC (toner flying control means) 12 ... Developing roller (toner carrier) 23 ... Intermediate transfer belt (image receptor) 41 ... Toner passage hole J: Toner flight start position T ... toner

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Atsushi Kitazawa             Seiko, 3-3-3 Yamato, Suwa City, Nagano Prefecture             -In Epson Corporation F term (reference) 2H005 AA08 AA25 CB07 CB13 EA07                 2H029 DB04

Claims (2)

[Claims] 1. A toner flying control means is provided between a toner carrying body carrying a toner and a back electrode, and the toner is carried from the toner carrying body to the back side through a toner passage hole provided in the toner flying control means. A toner used in an image forming apparatus of a toner jet type that forms a toner image by causing the toner to fly toward an electrode and landing the toner on an image receiving body that is conveyed between the toner flying control means and the back electrode. It has a mother particle, a silica external additive, and a titanium oxide external additive, and the titanium oxide content x satisfies the following formula: 0 <x ≦ 1.5 wt%. The toner used in the image forming apparatus of the characteristic toner jet system. 2. The toner used in an image forming apparatus of a toner jet type according to claim 1, wherein the titanium oxide content x satisfies the following formula: 0.2 wt% ≦ x ≦ 1.0 wt%.