JPH09109440A - Powder jet image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a powder jet image forming apparatus capable of preventing the occurrence of unevenness of density. SOLUTION: This matrix electrode of a printing head is divided into a plurality of parts in the recording paper transportation direction, and respective matrix electrodes 111, 112 divided are arranged at given distances in the recording paper transportation direction, and developer supply rollers 121, 122 are put respectively in each divided matrix electrode 111, 112.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder jet image forming apparatus.

[0002]

2. Description of the Related Art First, the basic structure of a powder jet image forming apparatus will be described with reference to FIG. In the powder jet image forming apparatus, the recording paper P is guided by the guide plate 5, and the base roller (base electrode) 3,
It is discharged through the fixing roller 4. The print head 2 is disposed below the base roller 3.

Toner is supplied to the print head 2 from a toner supply unit 10. The toner is assumed to be negatively charged in this example.

The toner supply unit 10 comprises a casing 11 filled with toner, a stirring pad 6 rotatably arranged in the casing 11, and a toner supply roller 1 rotatably arranged in the casing 11. . Stirring pad 6
The toner supply roller 1 is driven to rotate in a predetermined direction by a motor (not shown).

As shown in FIGS. 7 and 8, the print head 2 includes an insulating substrate (insulating layer) 20 and a plurality of first electrodes 21 formed on the surface of the insulating substrate 20 on the toner supply roller 1 side.
And a plurality of second electrodes 22 formed on the surface of the insulating substrate 20 on the base roller 3 side. Multiple first electrodes 2
The one and the plurality of second electrodes 22 form a matrix electrode. Each first electrode 21 and each second electrode 22
A toner insertion hole 23 penetrating the print head 2 is formed at each intersection position of and.

The print head 2 is provided with an ultrasonic vibrator 50 for applying ultrasonic vibration to the print head 2 to prevent the toner insertion hole 23 from being clogged with toner.

The recording paper P is moved by the base roller 3 in a direction orthogonal to the first electrode 21 (direction shown by arrow A in FIG. 7).
Transported to

An on-voltage (for example -100V) and an off-voltage (for example + 300V) are selectively applied to each first electrode 21. Each second electrode 22 has an on-voltage (for example, 0 V) and an off-voltage (for example, -200 V).
V) and are selectively applied.

FIG. 9 shows the applied voltage V1- to each first electrode 21.
The change of 1-V1-8 is shown. As shown in FIG.
Dynamic scanning control is applied to each first electrode 21, and the applied voltage is sequentially turned on at predetermined unit time intervals. Then, only when the applied voltage to both the first electrode 21 and the second electrode 22 is the on-voltage, the toner insertion hole 23 at the intersection thereof is applied.
The toner passes through and dot printing is performed.

For example, 0V is applied to the toner supply roller 1.
And a binary periodic voltage of 150 V is applied. A voltage of +200 V, for example, is applied to the base roller 3.

[0011]

In the above powder jet image forming apparatus, the toner supply roller 1 and the first electrode 2 are provided.
The toner is supplied from the toner supply roller 1 side onto the first electrode 21 by the electric field between the toner supply roller 1 and the first electrode 21. Then, by the electric field between the first electrode 21 and the second electrode 22, the first electrode 2
The toner accumulated on the sheet 1 passes through the toner insertion hole 23 and is transferred onto the recording paper.

The toner is supplied from the toner supply roller 1 to the print head 2 by the action of an electric field (toner supply electric field) generated by the difference between the potential of the toner supply roller 1 and the potential of the first electrode 21. . However, as shown in FIG. 10, since the outer surface of the toner supply roller 1 is a curved surface, the shortest distance between each first electrode 21 of the print head 2 and the outer surface of the toner supply roller 1 is different. Therefore, the toner supply electric field in the vicinity of the first electrode 21 varies between the first electrodes 21, and uneven density occurs. Especially when black solid printing is performed, white streaks appear.

FIG. 11 shows the two second electrodes 2 on the left side of FIG.
The toner insertion hole 23 formed in
It shows that the rows are solidly printed in black.

The first row of the recording paper is the first electrode 21 of the first stage.
When it is transported to the print position of -1, the first
Dot printing is performed by the toner insertion hole 23 located at the intersection of the electrode 21-1 and the second electrode 22. That is,
The first row of the recording paper of FIG. 11 and the first electrode 21- of the first stage
The dot at the intersection with 1 is printed.

The first row of the recording paper is the first electrode 21 of the second stage.
-2, when it is transported to the printing position,
Dot printing is performed by the toner insertion hole 23 located at the intersection of the electrode 21-2 and the second electrode 22. That is,
The first row of the recording paper of FIG. 11 and the first electrode 21- of the second row
The dot at the intersection with 2 is printed.

By the same operation, the third line is printed on the first line of the recording paper.
When dot printing is performed by the first electrodes 21-3 to 21-8 on the eighth stage, the black solid printing on the first row of the recording paper ends.

As shown in FIG. 10, the first of the first to eighth stages
Since the distance from the toner supply roller 1 to the first electrodes 21 on both sides of the electrode 21 increases, the toner supply electric field becomes weaker. Therefore, among the first electrodes 21 of the first to eighth stages, the first electrodes 21 on both sides have a lower image density. That is, as shown in FIG. 11, the first electrode 2 of the first to eighth stages
In the case of No. 1, the printed dots are smaller on the first electrodes 21 on both sides. Therefore, in particular, the first electrode 21- of the first stage
White streaks occur between the print dots of 1 and the print dots of the first electrode 21-8 of the eighth stage.

An object of the present invention is to provide a powder jet image forming apparatus capable of preventing uneven density.

[0019]

SUMMARY OF THE INVENTION A powder jet image forming apparatus according to the present invention comprises a plurality of first electrodes formed on the surface of a developer supply roller having an insulating layer and a recording paper conveying section having an insulating layer. A matrix-shaped electrode portion is formed by the plurality of second electrodes formed on the surface, and a developer insertion hole is formed at each intersection of the first electrode and the second electrode. In one powder jet image forming apparatus, one electrode has a print head that extends in the length direction of the developer supply roller and is arranged at intervals in the recording paper conveyance direction orthogonal to the length direction of the developer supply roller. The matrix-shaped electrode portion of the print head is divided into a plurality of pieces in the recording paper conveyance direction, and the divided matrix-shaped electrode portions are arranged at predetermined intervals in the recording paper conveyance direction. Electrode part DOO in, wherein the developer feed roller, respectively.

In each of the divided matrix-shaped electrode portions, dots output by the first electrodes at the upstream end and the downstream end of the arbitrary matrix-shaped electrode portion in the recording paper conveyance direction and the recording of other matrix-shaped electrode portions are performed. It is preferable that the dots output by the first electrode at the central portion in the paper transport direction are arranged adjacent to each other on the recording paper in the direction orthogonal to the recording transport direction.

In the powder jet image forming apparatus according to the present invention, the length of each matrix electrode portion in the recording paper conveyance direction is shorter than the length of the matrix electrode portion of the conventional print head in the recording paper conveyance direction. A developer supply roller is provided for each matrix electrode part. For this reason, the variation in the distance between each first electrode and the developer supply roller between each first electrode of each matrix-shaped electrode portion is reduced as compared with the conventional case. For this reason, density unevenness due to variation in the distance between each first electrode and the developer supply roller is reduced.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS.

FIG. 1 shows a powder jet image forming apparatus.

In this powder jet image forming apparatus,
The recording paper is guided by the conveyor belt 101, is fed below the base electrode 102, and is conveyed toward a fixing roller (not shown). A print head 103 is arranged below the base electrode 102.

The print head 103 has two matrix-shaped electrode portions 111, 1 spaced apart in the recording paper conveyance direction.
12 are formed. Each matrix electrode part 111,
The toner supply rollers 12 are separately provided below the position 112.
1, 122 are arranged.

As shown in FIG. 2, one of the matrix-shaped electrode portions (hereinafter referred to as the first matrix-shaped electrode portion) 111 is located upstream of the matrix-shaped electrode portion of the conventional print head of FIG. It is the same as the half configuration. As shown in FIG. 2, the other matrix-shaped electrode portion 112 (hereinafter, referred to as a second matrix-shaped electrode portion) is located on the downstream side of the matrix-shaped electrode portion of the conventional print head in FIG. Same as half configuration.

That is, the first matrix electrode section 111
Is an insulating layer and the first to fourth stage first electrodes 21-1 to 21-21 formed on the surface of the insulating layer on the toner supply roller 121 side.
-4 and a plurality of second electrodes 22 formed on the base electrode 102 side of the insulating layer. Each first electrode 21-1 to 21-1
A toner insertion hole 23 is formed at the intersection of 21-4 and the second electrode 22.

The second matrix electrode section 112 is insulated from the insulating layer and the first to fifth electrodes 21-5 to 21-8 of the fifth to eighth stages formed on the surface of the insulating layer on the toner supply roller 122 side. And a plurality of second electrodes 22 formed on the base electrode 102 side of the layer. Each first electrode 21-5 to 21-8
And the toner insertion hole 23 at the intersection with the second electrode 22.
Are formed.

The recording paper is first sent to the first matrix electrode section 111, and printing is performed by the first matrix electrode section 111. After that, the recording paper is sent to the second matrix electrode section 112, and the second matrix electrode section 1
Printing is performed by 12.

In such an image forming apparatus, the length of each matrix-shaped electrode portion 111, 112 in the recording paper conveyance direction is
The length is shorter than the length of the matrix-shaped electrode portion of the conventional print head in the recording paper conveyance direction. Then, the toner supply rollers 121 and 12 are provided for each of the matrix-shaped electrode portions 111 and 112.
2 are provided. Therefore, the variation in the distance between each first electrode and the toner supply roller 121 between each first electrode 21-1 to 21-4 of the first matrix electrode portion 111 is reduced as compared with the conventional case. Similarly, the variation in the distance between each first electrode and the toner supply roller 122 between the first electrodes 21-5 to 21-8 of the second matrix electrode portion 112 is reduced as compared with the conventional case. For this reason, density unevenness due to variation in the distance between each first electrode and the toner supply roller is reduced.

As shown in FIG. 3, the lead-out directions of the lead portions of the first and second electrodes of the first matrix electrode portion 111 and the first and second electrodes of the second matrix electrode portion 112. The lead-out direction of the lead part may be reversed.

FIG. 4 is a block diagram showing a print head as shown in FIG.
Two second electrodes 22 (second electrodes shown in the lower side of FIG. 4) and two second electrodes 22 (upper side of FIG. 4) of the second matrix-like electrode portion 112 corresponding to these second electrodes 22. Second electrode shown in FIG.

However, here, an example is shown in which each of the matrix-shaped electrode portions 111 and 112 is provided with a first electrode in six stages. That is, in the first matrix-shaped electrode portion 111, the first to sixth stages of the first electrodes 21-1 to 21-21 are provided.
-6 is formed, and the second matrix electrode portion 112 is formed.
Include the first electrodes 21-7 to 21-1 of the seventh to twelfth stages.
2 are formed. The toner insertion hole 23 formed in each of the second electrodes 22 has the first electrode 21- of the first stage from the lower side.
It corresponds to the first electrodes 21-12 of the 1st to 12th stages.

In the case of black solid printing, first, when a predetermined row of recording paper is conveyed to the printing position by the first electrode 21-1 of the first stage, it is transferred to the first electrode 21-1 of the first stage. Dots are printed by the corresponding toner insertion holes 23. When a predetermined row of the recording paper is conveyed to the printing position by the first electrode 21-2 of the second stage, dots are printed by the toner insertion holes 23 corresponding to the first electrode 21-2 of the second stage. It Hereinafter, similarly, the first electrode 2 of the third to twelfth stages
Dots are printed by 1-3 to 21-12.

By the way, each matrix-shaped electrode portion 111,
In 112, the first electrodes on the upstream side and the downstream side in the recording paper conveyance direction have a larger distance from the toner supply roller than the first electrode at the central portion, and thus the print dots are small. In the arrangement of FIG. 4, the print dots by the first electrode 21-6 in the sixth row and the print dots by the first electrode 21-7 in the seventh row are adjacent to each other. Further, the print dots formed by the first electrode 21-12 in the 12th row and the print dots formed by the first electrode 21-1 in the first row are adjacent to each other. That is, in the arrangement of FIG. 4, small print dots are adjacent to each other, and therefore white streaks may occur between these small print dots.

Therefore, the first matrix electrode section 111
And the second matrix electrode portion 112 are preferably arranged as shown in FIG.

That is, in the arrangement shown in FIG. 5, among the first electrodes of the first matrix-like electrode portion 111, the toner insertion hole 23 of the first electrode 21-3 of the third stage in the central portion in the recording paper conveyance direction is formed. And the toner insertion hole 23 of the first electrode 21-4 of the fourth stage
Between the first electrode of the second matrix electrode portion 112, the toner insertion hole 23 of the first electrode 21-7 of the seventh stage at the upstream side end in the recording paper conveyance direction, or the recording paper conveyance position. Electrode 21-12 of the twelfth stage at the downstream end in the direction
This corresponds to the toner insertion hole 23.

Further, among the first electrodes of the second matrix-like electrode portion 112, the toner insertion hole 23 of the first electrode 21-9 of the ninth step and the tenth step of the tenth step in the central portion in the recording paper conveyance direction. At a position between the first electrode 21-10 and the toner insertion hole 23,
Among the first electrodes of the first matrix-like electrode portion 111, the first electrode 21- of the first stage at the upstream end in the recording paper transport direction
1 or the toner insertion hole 23 of the first electrode 21-6 of the sixth stage at the downstream end in the recording paper conveyance direction.
Is supported.

With such an arrangement, relatively large print dots printed by the first electrodes at the central portion of the first matrix electrode portion 111 in the recording paper conveyance direction and recording paper conveyance of the second matrix electrode portion 112. Adjacent to a relatively small print dot printed by the first electrode located upstream or downstream in the direction. Further, a relatively large print dot printed by the first electrode at the center of the second matrix electrode portion 112 in the recording paper conveyance direction, and the upstream or downstream side of the first matrix electrode portion 111 in the recording paper conveyance direction. Adjacent to a relatively small print dot printed by the first electrode at. Therefore, white streaks are less likely to occur.

In the above embodiment, an example in which the necessary matrix electrode is divided into two matrix electrode portions has been described, but the necessary matrix electrode is divided into three or more matrix electrode portions. May be.

[0041]

According to the present invention, a powder jet image forming apparatus capable of preventing the occurrence of uneven density can be obtained.

[Brief description of the drawings]

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

FIG. 2 is a plan view showing a print head.

FIG. 3 is a plan view showing another example of the print head.

FIG. 4 is a partial plan view showing an arrangement example of first matrix-shaped electrode portions and second matrix-shaped electrode portions.

FIG. 5 is a partial plan view showing a preferred arrangement example of first matrix-shaped electrode portions and second matrix-shaped electrode portions.

FIG. 6 is a configuration diagram showing a basic configuration of a powder jet image forming apparatus.

FIG. 7 is a plan view showing the basic structure of the print head.

8 is a sectional view taken along line aa of FIG.

FIG. 9 is a time chart showing changes in voltage applied to each first electrode.

FIG. 10 is a cross-sectional view showing a positional relationship between a first electrode and a toner supply roller.

FIG. 11 is a schematic diagram for explaining how the first row of recording paper is solidly printed in black.

[Explanation of symbols]

 20 Insulating Layer 21 First Electrode 22 Second Electrode 23 Toner Insertion Hole 101 Conveyor Belt 102 Base Electrode 103 Print Head 111 First Matrix Electrode Part 112 Second Matrix Electrode Part 121, 122 Toner Supply Roller

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuki Ito 1-2-2 Tatamazo, Chuo-ku, Osaka City, Osaka Prefecture Mita Kogyo Co., Ltd. (72) Atsushi Fujii 1-2 Tatamazo, Chuo-ku, Osaka City, Osaka No. 28 Mita Industry Co., Ltd.

Claims (2)

[Claims] 1. A matrix comprising a plurality of first electrodes on which a developer supply roller of an insulating layer is formed on the wrinkle surface, and a plurality of second electrodes on which a recording paper conveying portion of the insulating layer is formed on the wrinkle surface. -Shaped electrode portions are formed, a developer insertion hole is formed at each intersection of the first electrode and the second electrode, and the plurality of first electrodes extend in the length direction of the developer supply roller. In a powder jet image forming apparatus having print heads arranged at intervals in the recording paper conveyance direction that is orthogonal to the lengthwise direction of the developer supply roller, the matrix electrodes of the print head are Each of the divided matrix-like electrode portions is arranged at a predetermined interval in the recording paper conveyance direction, and a developer supply roller is provided for each of the divided matrix-like electrode portions. Characterized by That powder jet image forming apparatus. 2. The divided matrix-shaped electrode portions are dots output by the first electrodes at the upstream and downstream ends of the arbitrary matrix-shaped electrode portion in the recording paper conveyance direction, and
2. The dot arranged by the first electrode at the center of the other matrix-shaped electrode portion in the recording paper conveyance direction is arranged so as to be adjacent on the recording paper in the direction orthogonal to the recording conveyance direction. Powder jet image forming device.