JPH09109439A - Printing head in powder jet image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printing head for a power jet image forming device capable of preventing the occurrence of white steps in a blackened printing part. SOLUTION: At the downstream side in the recording paper transportation direction of a first electrode 21-8 disposed at the most downstream side from the recording paper transportation direction or the upstream side in the recording paper transportation direction of a first electrode 21-1 disposed at the most upstream side from the recording paper transportation direction, an auxiliary electrode 21-9 is provided in parallel with the first electrode 21. Also, at each intersection position of the auxiliary electrode 21-8 and second electrode 22, and at each intermediate position between dots to be printed by the first electrode 21-8 at the most downstream side from the recording paper transportation direction and dots to be printed by the first electrode 21-1 at the most upstream side from the recording paper transportation direction, a developer insertion hole 24 is made for printing dots.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art First, the basic construction 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. 5 and 6, 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. 5).
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. 7 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. 8, 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. For this reason, the electric field for toner supply in the vicinity of the first electrodes 21 varies between the first electrodes 21, and white streaks appear in solid black printing.

FIG. 9 shows two second electrodes 22 on the left side of FIG.
The toner insertion holes 23 formed on the first recording medium are used to print solid black on the first row of the recording paper.

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. 9 and the first electrode 21-1 of the first stage
The dot at the intersection with 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 electrode 21-2 of the first row and the second row of the recording paper of FIG.
The dot at the intersection with 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. 8, among the first electrodes 21 of the first to eighth stages, the first electrodes 21 on both sides have a larger distance from the toner supply roller 1, so that 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. 9, the first electrode 21 of the first to eighth stages
Among them, the first electrodes 21 on both sides have smaller print dots. Therefore, in particular, the first electrode 21-1 of the first stage
A white streak is generated between the print dot formed by (1) and the print dot formed by the first electrode 21-8 on the eighth stage.

An object of the present invention is to provide a print head in a powder jet image forming apparatus capable of preventing the occurrence of white streaks in a black solid print portion.

[0019]

A print head in a powder jet image forming apparatus according to the present invention comprises a plurality of first electrodes formed on a surface of a developer supply roller of an insulating layer, and a recording paper conveying of the insulating layer. A matrix-shaped electrode portion is formed by a plurality of second electrodes formed on the surface of the portion, and a developer insertion hole is formed at each intersection of the first electrode and the second electrode. The first electrode of the book extends in the lengthwise direction of the developer supply roller and is arranged at intervals in the recording paper conveyance direction orthogonal to the lengthwise direction of the developer supply roller. In the recording paper conveyance direction, the first electrode is provided on the downstream side of the first electrode on the most downstream side in the recording paper conveyance direction or on the upstream side of the first electrode on the most upstream side in the recording paper conveyance direction in the recording paper conveyance direction. Parallel to Electrodes are provided, at the intersection of the auxiliary electrode and the second electrode, the dot printed by the first electrode on the most downstream side in the recording paper conveyance direction and the dot printed on the most upstream side in the recording paper conveyance direction. It is characterized in that a developer insertion hole for printing a dot is formed at an intermediate position of the dot printed by one electrode.

The positions of the developer insertion holes formed in the auxiliary electrodes are specifically as follows. That is, the same second
On the electrode, the developer insertion hole formed in the auxiliary electrode and the developer insertion hole formed in the first electrode adjacent to the auxiliary electrode have the same distance in the length direction of the first electrode on the same second electrode. In, the length is 1/2 of the pitch in the lengthwise direction of the first electrodes of the developer insertion holes of the adjacent first electrodes. Also, the same second
On the electrode, the distance between the developer insertion hole formed in the auxiliary electrode and the developer insertion hole formed in the first electrode adjacent to the auxiliary electrode in the direction orthogonal to the length direction of the first electrode is the same. On the second electrode, the length is the same as the pitch of the developer insertion holes of the adjacent first electrodes in the direction orthogonal to the length direction of the first electrode.

With the print head in the powder jet image forming apparatus according to the present invention, during solid black printing,
By the auxiliary electrode, a dot is printed at an intermediate position between the dot printed by the first electrode on the most downstream side in the recording paper conveyance direction and the dot printed by the first electrode on the most upstream side in the recording paper conveyance direction. Since it is printed, at the time of solid black printing, the dots printed by the first electrode on the most downstream side in the recording paper conveyance direction and the dots printed by the first electrode on the most upstream side in the recording paper conveyance direction It is possible to prevent white streaks from occurring in the interposition.

[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 print head. In FIG. 1, an arrow A indicates the recording paper conveyance direction.

This print head is an auxiliary device for preventing the occurrence of white streaks on the downstream side of the first electrode 21-8 of the eighth stage of the print head described with reference to FIGS. 4 to 6 in the recording paper conveyance direction. The first electrode (hereinafter, referred to as an auxiliary electrode) 21-9 is provided. A toner insertion hole (hereinafter referred to as an additional hole) 24 is also provided at the intersection of the auxiliary electrode 21-9 and the second electrode 22.

FIG. 2 shows the toner insertion hole 23 and the additional hole 24 on the same second electrode 22. The length direction of the first electrode 21 will be referred to as the X direction, and the direction orthogonal to the first electrode 21 will be referred to as the Y direction.

The distance H in the Y direction between the toner insertion hole 23 of the first electrode 21-8 of the eighth stage and the additional hole 24 is the Y-direction pitch α of the first electrodes 21 of the first to eighth stages. Is equal to The distance W in the X direction between the toner insertion hole 23 of the first electrode 21-8 of the eighth step and the additional hole 24 is the first step from the first step to the eighth step.
It is 1/2 of the X-direction pitch β of the electrodes 21.

Assuming that the Y-direction pitch α of the first electrodes 21 of the first to eighth stages is 392 μm, the first electrodes 2 of the eighth stage
The interval H in the Y direction between the toner insertion hole 23 and the additional hole 24 of 1-8 is also 392 μm. Eighth stage first electrode 21-8
Distance W between the toner insertion hole 23 and the additional hole 24 in the X direction
Is the X-direction pitch β of the first electrodes 21 of the first to eighth stages
Is 32 μm.

FIG. 3 shows the two second electrodes 22 on the left side of FIG.
The toner insertion holes 23 formed on the first recording sheet form a solid black print on the first row of the recording paper.

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. 3 and the first electrode 21-1 of the first stage
The dot at the intersection with 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. 3 and the first electrode 21-2 of the second stage
The dot at the intersection with is printed.

By the same operation, dot printing is performed on the first row of the recording paper by the first electrodes 21-3 to 21-8 on the third to eighth stages. In this state, it is the same as the conventional example of FIG.

After this, the first row of the recording paper is the auxiliary electrode 21-.
9 is conveyed to the print position by the auxiliary electrode 21-9.
Dot printing is performed by the additional hole 24 located at the intersection of the second electrode 22 and the second electrode 22. The dots at the intersections of the first row of the recording paper of FIG. 3 and the auxiliary electrodes 21-9 are printed. That is, the print dots by the first electrode 21-1 of the first stage,
A dot is printed by the auxiliary electrode 21-9 at an intermediate position between the dot printed by the first electrode 21-8 in the eighth row and the print dot.

Therefore, as in the conventional case, at the time of solid black printing, the white dot is formed between the print dot formed by the first electrode 21-1 on the first stage and the first electrode 21-1 on the eighth stage. Muscles will not occur.

In the above embodiment, the auxiliary electrode 21-9 is provided on the downstream side of the first electrode 21-8 in the eighth stage in the recording paper conveyance direction.
However, an auxiliary electrode may be provided on the upstream side of the first electrode 21-1 of the first stage in the recording paper conveyance direction.

During solid black output, all the first electrodes 21-1 to 21-9 are dynamically controlled for printing, and when solid black output is not performed, the first electrode 21-1 to 21-9 is printed in the same manner as in the conventional case.
Printing may be performed by dynamically controlling the first electrodes 21-1 to 21-8 from the first to the eighth stages.

[0036]

According to the present invention, it is possible to obtain a print head in a powder jet image forming apparatus capable of preventing the occurrence of white streaks in a solid black print portion.

[Brief description of the drawings]

FIG. 1 is a plan view showing a print head according to an embodiment of the present invention.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a schematic diagram for explaining how the first row of recording paper is solidly printed in black.

FIG. 4 is a configuration diagram showing a basic configuration of a powder jet image forming apparatus.

FIG. 5 is a plan view showing the basic structure of the print head.

6 is a cross-sectional view taken along the line aa of FIG.

FIG. 7 is a time chart showing changes in applied voltage to each first electrode.

FIG. 8 is a cross-sectional view showing a positional relationship between a first electrode and a toner supply roller.

FIG. 9 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 21-9 auxiliary electrode 23 toner insertion hole 24 additional hole (toner insertion hole)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroyuki Yamaji, 1-2-2 Tamatsukuri, Chuo-ku, Osaka-shi, Osaka Mita Kogyo Co., Ltd. No. 28 Inside 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 addition, in the print head in the powder jet image forming apparatus, which is arranged at intervals in the recording paper conveyance direction orthogonal to the length direction of the developer supply roller, recording of the first electrode on the most downstream side in the recording paper conveyance direction An auxiliary electrode is provided in parallel to the first electrode on the upstream side in the recording paper conveyance direction of the first electrode located on the downstream side in the paper conveyance direction or the most upstream side in the recording paper conveyance direction. The auxiliary electrode and the second electrode At the intersection of the The in flow side 1
A developer insertion hole for printing dots is formed at an intermediate position between the dots printed by the electrodes and the dots printed by the first electrode on the most upstream side in the recording paper conveyance direction. A print head for a powder jet image forming apparatus. 2. On the same second electrode, a developer insertion hole formed in the auxiliary electrode and a developer insertion hole formed in the first electrode adjacent to the auxiliary electrode are arranged in the longitudinal direction of the first electrode. The interval is half the pitch in the lengthwise direction of the first electrodes of the developer insertion holes of the first electrodes adjacent to each other on the same second electrode. The distance between the developer insertion hole formed in the electrode and the developer insertion hole formed in the first electrode adjacent to the auxiliary electrode in the direction orthogonal to the length direction of the first electrode is the same on the second electrode. , Next to each other
The print head in the powder jet image forming apparatus according to claim 1, wherein the developer insertion holes of the electrodes have the same length as the pitch in the direction orthogonal to the length direction of the first electrodes.