JPH09277582A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a high quality image to be formed even when an aperture electrode is obliquely arranged on a support by setting an angle formed by a straight line connecting the center of an opening for passage of a charged body in a charged body control means to the center of the charged body and by the surface of the support opposite to the opening to be a specific angle. SOLUTION: An aperture electrode 1 consisting of a back electrode roller 22, a toner supply device 10 and a fixing device 26 has plural apertures 6, penetrating through an insulating sheet 2, which are aligned at an equal interval in a single row, and a control electrode 4 is formed on the peripheral edge of each of the apertures 6 on the upper face side of the insulating sheet 2. In this case, an angle (α) formed by a straight line connecting the center of the aperture 6 to the center of a toner carrying roller 14 and a tangential line to the surface of a support 20 opposite to the aperture 6 is set to be about 45 deg.<=α<90 deg. or 90 deg. < α <= about 135 deg.. Thus it is possible to minimize the irregularity of time, for a charged body to arrive at a sheet, which is generated in accordance with a scatter distance, and thereby form a high-quality image.

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 which can be used for a copying machine, a printer, a plotter, a facsimile, and the like.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus for obtaining an image on a support by controlling the passage of toner particles through an aperture by applying an image signal to an electrode having an aperture has been proposed in US Pat. No. 3,689,935. Has been done.

The image forming apparatus described in US Pat. No. 3,689,935 is composed of a shield electrode which is continuous on one side with a layer of an insulator interposed therebetween and a plurality of control electrodes which are insulated from each other on the other side. And is formed through three layers for each insulated plurality of control electrodes and at least 1
An aperture electrode body having apertures arranged in a row,
A means for selectively applying an electric potential between the control electrode and the shield electrode, a means for supplying charged toner particles to the aperture of the aperture electrode body, and a high voltage device arranged on the opposite side of the aperture electrode body of the support. And a means for moving the support relative to the aperture electrode body to position the support in the particle channel.

However, according to this apparatus, the toner particles are clogged in the aperture to deteriorate the recording quality, and
I couldn't make the recording speed too fast.

The applicant of the present invention further studied, and disclosed in Japanese Patent Laid-Open No. 6-
As disclosed in Japanese Patent No. 155798, there is proposed an image recording apparatus capable of greatly improving recording characteristics by disposing a carrier holding toner and an aperture electrode body in contact with each other. According to this apparatus, the aperture is not clogged, the image quality is remarkably improved, and it is possible to reduce the size and cost of the image recording apparatus.

In order to reduce the size of such an image recording apparatus, the aperture electrode 1 and the support 20 are arranged at an angle α, as shown in FIG. Was being done.

[0007]

However, in such an image forming apparatus, it has been found that the arrangement state of the recording unit having the aperture electrodes and the support has an important influence on the image quality. In other words, it has been found that, due to restrictions such as sheet conveyance, when the aperture electrode and the support are arranged at an angle, the printed image may be disturbed.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an image forming apparatus having excellent image quality even when the aperture electrode is obliquely arranged with respect to the support. I am aiming.

[0009]

In order to achieve this object, an image forming apparatus according to a first aspect of the present invention has an opening for passing a charged body and a control electrode for controlling the passage of the charged body. The charged body control means, the charged body carrier for supplying the charged body to the charged body control means, and the back electrode provided on the opposite side of the charged body carrier from the charged body carrier. , For controlling the passage of a charged body supplied by a charged body carrier through the opening to form an image on a support supported on a back electrode, in particular, the center of the opening and the charged body. A straight line connecting the center of the body support,
The angle α formed by the surface of the support facing the opening is about 45 ° ≦ α <90 ° or 90 ° <α ≦ about 135 °. Therefore, even if the initial velocity of the charged body varies, the contribution to the transport direction component of the support body is small, and the print is not disturbed. Further, the distance that the charged body discharged from the opening flies in the electric field becomes short. As a result, even if the initial velocity of the flying charged body fluctuates, it is possible to reduce the variation in the arrival time to the paper depending on the flying distance, and a good image is formed.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an outline of an image forming apparatus according to the present invention, in which a columnar cylinder serving as a back electrode having a gap of 1 mm above an aperture electrode body 1 serving as a toner flow control means. The rear electrode roller 22 is rotatably arranged in a housing (not shown), and is configured to be able to convey the support body 20 inserted in the gap. The aperture electrode body 1 constitutes the charged body control means of the present invention.

Below the aperture electrode body 1, along the longitudinal direction of the aperture electrode body 1, the toner supply device 1 is provided.
0 is disposed, and a transport roller 29 for transporting the support 20 between the aperture electrode body 1 and the back electrode roller 22 is rotatably arranged on the carry-in side of the aperture electrode body 1. Further, the fixing device 26 is installed at the destination of the support 20 conveyed by the back electrode roller 22.
Are arranged. The back electrode roller 22 constitutes the back electrode of the present invention.

Next, the respective components will be described in detail. In the toner supply device 10, the toner case 11 also serving as a housing of the entire device, the toner 16 housed in the toner case 11, and the supply roller 12 are provided. And a toner carrying roller 14 and a toner layer regulating blade 18. Here, the toner carrying roller 1
Reference numeral 4 is for carrying the toner 16 in layers and conveying it toward the aperture electrode body 1. The supply roller 12 is for supplying the toner 16 to the toner carrying roller 14. The toner 16 constitutes the charged body of the present invention, and the toner carrying roller 14 constitutes the charged body carrying body.

The supply roller 12 and the toner carrying roller 14 are rotatably supported in the toner case 11 in the direction of the arrow shown in FIG. Further, the toner layer regulating blade 18
Is for adjusting the amount of toner 16 carried on the toner carrying roller 14 to be uniform on the roller surface and for uniformly charging the toner 16, and is pressed against the toner carrying roller 14.

As shown in FIG. 2, the aperture electrode body 1 comprises a polyimide insulating sheet 2 having a thickness of 25 μm, and a plurality of apertures 6 having a diameter of 100 μm penetrating the insulating sheet 2 arranged in a row at equal intervals. In addition, the control electrode 4 as a toner flow control unit is formed with a thickness of 1 μm on the peripheral edge of the opening of each aperture 6 on the upper surface side of the insulating sheet 2. As shown in FIG. 1, when the control electrode 4 is opposed to the support member 20, the aperture electrode body 1
4 is provided so as to be in contact with the upper toner. A control voltage applying circuit 8 is connected to the control electrode 4, and is +20 V (ON voltage) or −20 relative to the control electrode 4 based on image data input from a data input unit (not shown).
V (OFF voltage) can be selectively applied.

The rear electrode roller 22 is the aperture electrode body 1.
It is arranged so as to face the toner carrying roller 14 through the aperture 6. The back electrode roller 22 is the aperture electrode body 1
Is disposed with a gap of about 1 mm, and is rotatably supported by a chassis (not shown). Therefore, the support P can be inserted into the gap between the back electrode roller 22 and the aperture electrode body 1. In addition, the back electrode roller 22
A DC power supply 24 is connected to the DC power supply 24.
Is configured to be able to apply a voltage of +1 kV to the back electrode roller 22.

The fixing device 26 comprises a heat roller 26a having a heat source inside, and a pressure roller 26b which is in pressure contact with the heat roller 26a. The image-formed support 20 has two rollers 26 a in the fixing device 26.
And 26b, and after the toner image is thermally fixed,
The sheet is discharged to the outside of the image forming apparatus from a discharge port (not shown).

Here, the angle α formed by the straight line connecting the center of the aperture 6 and the center of the toner carrying roller 14 and the tangent of the surface of the support 20 facing the aperture 6 is set to about 60 degrees ( (See FIG. 1).

Next, the operation of the image forming apparatus configured as described above will be described.

When an image forming command is input to the image forming apparatus from an external device (not shown), first, the toner carrying roller 14 and the supply roller 12 start rotating in the arrow direction shown in FIG. Then, the toner 16 carried and conveyed on the surface of the supply roller 12 is rubbed against the surface of the toner carrying roller, and is further negatively charged to be carried on the surface of the toner carrying roller 14. The carried toner 16 is uniformly thinned by the toner layer regulating blade 18 and is substantially uniformly charged, and then is conveyed toward the aperture electrode body 1 by the rotation of the toner carrying roller 14. Then, the toner 16 on the toner carrying roller 14 is supplied below the aperture 6 while being rubbed by the insulating sheet 2 of the aperture electrode body 1.

On the other hand, the support body 20 is sandwiched by a conveying roller (not shown) so that the aperture electrode body 1 and the back electrode roller 22 are provided.
It is transported between and.

Here, a voltage is applied to the control electrode based on the print data. The ON voltage (+ 20V) is applied to the printing area, and the OFF voltage (-2V) is applied to the non-printing area.
0 V) is applied from a control power supply (not shown). Control electrode 4
When an ON voltage (+20 V) is applied to the control electrode 4, a potential difference between the control electrode 4 and the toner carrying roller 14 forms an electric force line from the control electrode 4 toward the toner carrying roller 14. As a result, the negatively charged toner 16 becomes
The toner carrying roller 14 receives the electrostatic force in the direction of high potential.
It is pulled out from above through the aperture 6 to the control electrode 4 side. The extracted toner 16 is further applied to the support 2 by the voltage of +1 kV applied to the back electrode roller 22.
0 and the aperture electrode body 1 generate an electric field,
It flies toward the support 20. As a result, the support 20
The toner 16 that has flown toward the surface is deposited on the support 20 to form pixels.

Further, the control electrode 4 has an OFF voltage (-20
When V) is applied, electric lines of force from the toner carrying roller 14 to the control electrode 4 are formed. as a result,
Since the negatively charged toner receives an electrostatic force in the direction in which it is pressed against the carrying roller 14, it does not pass through the aperture electrode body 1.

The support 20 is conveyed by one pixel in the direction perpendicular to the aperture row by a support conveying roller (not shown) while the toner 16 forms a line of pixels on the surface of the support 20. Then, by repeating this process, a toner image representing a desired image is formed on the entire surface of the support 20. After that, the formed toner image is fixed on the support 20 by the fixing device 26.
Finally, the support 20 on which the toner image is formed is discharged from the discharge port (not shown) to the outside of the image forming apparatus, and the image forming process is completed.

Next, the relationship between the angle α formed by the straight line A connecting the center of the aperture 6 and the center of the toner carrying roller 14 and the tangent line B of the surface of the support 20 facing the aperture 6 and the disturbance of the printed image. Will be described with reference to FIG. FIG.
FIG. 6 is an explanatory diagram showing a toner flying state. Toner 16 in the figure
Shows a state of flying from the aperture at an angle of 30, 45, or 90 degrees with the support 20.
It is assumed that the toner 16 jumps out in the flying direction at the initial velocity V0. This initial velocity is decomposed into an X-direction component Vx and a Y-direction component Vy. At this time, Vx = V0COSα is expressed, but the value of Vx increases as the angle α decreases in the range of 0 ° ≦ α ≦ 90 °.

However, increasing Vx means that the difference in the initial velocity of the toner greatly affects the landing position of the toner on the paper. The toner on the carrier roller has not only variations related to the characteristics of the toner, such as particle size and shape, and the amount of charge, but also variations in the motion state of the toner sandwiched between the aperture electrode and the carrier roller. Toner that contains various variations is ejected from the aperture.
It appears as a difference in flight status. That is, the initial speed V0
Is different depending on the toner, and it is an important issue to prevent the difference from affecting printing.

In order to prevent such a difference in initial speed from affecting printing, it is necessary to reduce Vx, and therefore the angle α needs to be as close to 90 degrees as possible. Furthermore, according to our experimental study, the limit of the angle α as the printing condition is that when α = 45 degrees, that is, V
It has been found that x = 0.7 × V0. If such a condition, α is set to 45 to 135 degrees in both directions, even if variations in the flying state of the toner occur, the printing is less affected (see FIG. 4).

Further, by setting α in the above range, the flight distance is also shortened, and the time for exposure to a disturbance factor that disturbs the flight of the toner such as an air flow is shortened. for that reason,
Printing can be performed under better conditions.

The present invention is not limited to the embodiments described in detail above, and various modifications can be made without departing from the spirit of the invention.

In the above embodiment, the angle between the center line of the aperture electrode body 1 and the support 20 is defined as α, but
Instead of the support 20, the angle formed with the back electrode roller 22 may be α.

Further, in the above-mentioned embodiment, the so-called toner, which is a dry powder, has been described, but any printing material of a charged body can be applied. For example,
A good effect is exhibited for liquid developers such as liquid toner and charged ink.

Further, although a so-called monochromatic unit has been described in the above-mentioned embodiment, it is naturally applicable to a color machine having a plurality of units arranged therein.

[0033]

As is apparent from the above description, the image forming apparatus according to the first aspect of the present invention is provided with the opening for passing the charged body and the control electrode for controlling the passage of the charged body. The charged body control means, the charged body carrier for supplying the charged body to the charged body control means, and the charged body carrier are provided with a back electrode provided on the opposite side of the charged body control means. For controlling the passage of a charged body supplied by a body carrier through the opening to form an image on a support supported on a back electrode, particularly, the center of the opening and the charged body support. The angle α between the straight line connecting the center of the body and the surface of the support facing the opening is about 45 ° ≦ α <90 ° or 90 ° <α ≦ about 135 °. . Therefore, even if the initial velocity of the charged body varies, the contribution to the transport direction component of the support body is small, and the print is not disturbed. Further, the distance that the charged body discharged from the opening flies in the electric field becomes short. As a result, even if the initial velocity of the flying charged body fluctuates, it is possible to reduce the variation in the arrival time to the paper depending on the flying distance, and a good image is formed.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing a configuration of an aperture electrode body.

FIG. 3 is an explanatory diagram showing a flying state of toner.

FIG. 4 is an explanatory diagram showing an arrangement state of image forming apparatuses.

FIG. 5 is an explanatory diagram showing a configuration of a conventional image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Aperture electrode body 2 Insulating sheet 4 Control electrode 6 Aperture 14 Toner carrying roller

Claims (1)

[Claims] 1. A charged body control means comprising an opening for passing a charged body and a control electrode for controlling the passage of the charged body,
A charged body carrier for supplying a charged body to the charged body control means and a back electrode provided on the opposite side of the charged body carrier from the charged body control means are provided by the charged body carrier. In an image forming apparatus that controls the passage of the charged body through the opening to form an image on a support supported on a back electrode, a straight line connecting the center of the opening and the center of the charged body carrier , An angle α formed by the surface of the support facing the opening
The image forming apparatus is configured so that about 45 degrees ≦ α <90 degrees or 90 degrees <α ≦ about 135 degrees.