JPH08258320A - Powder jet image-forming apparatus - Google Patents

Abstract

PURPOSE: To provide a powder jet image-forming apparatus which can keep constant electric fields for supply of toners in the vicinity of first electrodes, without causing decrease in an image density and deterioration of images. CONSTITUTION: In this powder jet image-forming apparatus, an auxiliary electrode 300 with a plurality of developer openings 321 is set between a printing head 2 and a developer feed roller 1. The auxiliary electrode 300 is provided with an insulating layer 31, a first grid electrode 311 formed on a surface of the insulating layer 310 at the side of the developer feed roller, and a second grid electrode 312 formed on a surface of the insulating layer 310 at the side of the printing head. A passing direction of the developer to the openings 321 is controlled by controlling impressed voltages to the first grid electrode 311 and the second grid electrode 312.

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 The applicant has developed a powder jet image forming apparatus as shown in FIG. In this powder jet image forming apparatus, the recording paper P is guided by the guide plate 5 and discharged through the base roller (base electrode) 3 and the fixing roller 4. The print head 2 is disposed below the base roller 4.

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. 8 to 10, 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 passage hole 23 penetrating the print head 2 is formed at each intersection position with 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.

A rectangular grid-shaped metal grid electrode 30 is arranged between the print head 2 and the toner supply roller 1. In the grid electrode 30, a plurality of slits 31 parallel to the length direction of the second electrode 22 are formed at equal intervals in the length direction of the first electrode 21. Grid electrode 3
The both sides of 0 are fixed to the print head 2 via the spacers 40, so that the grid electrode 30 is fixed to the print head 2.
Attached to.

The recording paper P is moved by the base roller 3 in a direction orthogonal to the first electrode 21 (direction indicated by arrow A in FIG. 8).
Be 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. 11 shows each first electrode 2
1 shows changes in applied voltage V1-0 to V1-7.
As shown in FIG. 11, each of the first electrodes 21 is subjected to dimic scan control, 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 passes through the toner insertion hole 23 at the intersection thereof, and the 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 binary periodic voltage of 50 V and 150 V, for example, is applied to the grid electrode 30. For the base roller 3, for example,
A voltage of + 200V is applied.

[0011]

In the above powder jet image forming apparatus, the toner from the toner supply roller 1 side passes through the grid electrode 30 by the electric field between the toner supply roller 1 and the grid electrode 30. Further, due to the electric field between the grid electrode 30 and the first electrode 21, the toner that has passed through the grid electrode 30 is supplied onto the first electrode 21. Then, the first electrode 21 and the second electrode 2
Due to the electric field between the first and second electrodes 21, the toner accumulated on the first electrode 21 passes through the toner insertion hole 23 and is transferred onto the recording paper.

The reason why the grid electrode 30 is provided is as follows. That is, the toner is supplied from the toner supply roller 1 to the print head 2 by the action of the 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, since the outer surface of the toner supply roller 1 is a curved surface, the 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 each first electrode 21 varies. The grid electrode 30 is provided in order to make the toner supply electric field near each of the first electrodes 21 constant.

That is, each first electrode 21 and grid electrode 3
The distance from 0 is constant. Therefore, the toner supply electric field generated between each first electrode 21 and the grid electrode 30 can be made uniform.

However, when the grid electrode 30 is provided, when the toner is supplied from the toner supply roller 1 to the first electrode 21, the toner supply is hindered and the image density may be lowered. Further, when the toner is collected from the first electrode 21 to the toner supply roller 1, the toner collection is hindered, which causes image deterioration.

An object of the present invention is to provide a powder jet image forming apparatus which can make the toner supplying electric field in the vicinity of each first electrode constant and which does not cause reduction in image density and image deterioration.

[0016]

A powder jet image forming apparatus according to the present invention comprises a print head, a developer supply roller and a base electrode provided so as to sandwich the print head, and the print head comprises an insulating layer. A plurality of first electrodes formed on the surface of the insulating layer on the developer supply roller side, and a plurality of second electrodes formed on the surface of the insulating layer on the side of the base electrode, the first electrode and the second electrode Form a matrix-shaped electrode portion on the print head, and a developer insertion hole is formed at each intersection of the first electrode and the second electrode in the print head. The developer is supplied from the developer supply roller side to the first electrode side by the electric field between the two, and the developer supplied to the first electrode side is the first
In a powder jet image forming apparatus that passes through a developer insertion hole by an electric field between an electrode and a second electrode, an auxiliary electrode having a plurality of developer passage openings is provided between a print head and a developer supply roller. And the auxiliary electrode is
An insulating layer, a first grid electrode formed on the surface of the insulating layer on the developer supply roller side, and a second grid electrode formed on the surface of the insulating layer on the print head side are provided. By controlling the voltage applied to the two grid electrodes, the passage direction of the developer with respect to the developer passage opening is controlled.

When a developer recovery mode for recovering the developer is provided as an operation mode in addition to the print mode for performing printing, in each mode, the first grid electrode and the first grid electrode of the auxiliary electrode are used. The voltage applied to the two grid electrodes is controlled as follows.

That is, in the printing mode, the first grid electrode and the first grid electrode are so arranged that an electric field for moving the developer from the first grid electrode side to the second grid electrode side is generated in the developer passage opening of the auxiliary electrode. The voltage applied to the second grid electrode is controlled.

In the developer collecting mode, the first grid electrode and the first grid electrode are so arranged as to generate an electric field for moving the developer from the second grid electrode side to the first grid electrode side in the developer passage opening of the auxiliary electrode. The voltage applied to the second grid electrode is controlled.

[0020]

The auxiliary electrode having a plurality of developer passage openings is provided between the print head and the developer supply roller. The auxiliary electrode includes an insulating layer, a first grid electrode formed on the surface of the insulating layer on the developer supply roller side, and a second grid electrode formed on the surface of the insulating layer on the print head side. By controlling the voltage applied to the first grid electrode and the second grid electrode, the passage direction of the developer with respect to the developer passage opening is controlled.

[0021]

Embodiments of the present invention will be described below with reference to FIGS.

(1) Description of the configuration of the powder jet image forming apparatus.

FIG. 1 shows the structure of a powder jet image forming apparatus.

In FIG. 1, the same parts as those in FIG. 7 are designated by the same reference numerals and the description thereof will be omitted. This powder jet image forming apparatus is different from the powder jet image forming apparatus in FIG. 7 only in that an auxiliary electrode 300 having a different structure is used instead of the grid electrode 30 in FIG.

2 and 3 show the structure of the auxiliary electrode 300.

The auxiliary electrode 300 has an insulating layer 310 and a first surface formed on the surface of the insulating layer 310 on the toner supply roller 1 side.
It is composed of a grid electrode 311 and a second grid electrode 312 formed on the surface of the insulating layer 310 on the print head 2 side.

A second electrode of the print head 2 is provided on the auxiliary electrode 300.
A plurality of slits (developer passage openings) 321 parallel to the length direction of the electrode 22 are formed at equal intervals in the length direction of the first electrode 21 of the print head 2. The portion between the adjacent slits 321 in the auxiliary electrode 300 will be referred to as a bridge portion 322. Both sides of the auxiliary electrode 300 are
The auxiliary electrode 300 is attached to the print head 2 by being fixed to the print head 2 via a spacer (not shown).

The pitch of the slits 321 of the auxiliary electrode 300, that is, the sum of the width of the slit 321 and the width of the bridge portion 322 is the same as the pitch of the toner insertion holes 23 on the first electrode 21. The auxiliary electrode 300 has the bridge portion 3
The print head 2 is attached so that the center of the width of 22 corresponds to the center of the width of the second electrode 22. Bridge 32
Is larger than the diameter of the toner insertion hole 23 so as to cover the toner insertion hole 23. If the developer is a one-component developer composed of toner, the slit 3
The width of 21 is made larger than the particle diameter (diameter) of the toner. When the developer is a two-component developer composed of toner and carrier, the width of the slit 321 is made larger than the particle diameter (diameter) of the carrier.

The auxiliary electrode 300 as described above is manufactured using a double-sided printed pattern substrate having conductive layers formed on both sides of an insulating layer. In other words, on both sides of the insulating layer to the conductive layer,
By etching, the slit 321 part is removed,
First grid electrode 311 and second grid electrode 312
Are formed respectively. After this, by laser processing etc.,
The insulating layer is provided with slits communicating with the openings of the electrodes 311 and 312. Thereby, the auxiliary electrode 300 is obtained.

The operation modes of the image forming apparatus include a printing mode for printing on a page-by-page basis and a toner collection mode for collecting toner in the toner supply section 10. After printing one page is completed by the print mode,
Before the printing of the next one page is started, the process in the toner collecting mode is performed. That is, the operation mode is set to the toner collecting mode for a certain period immediately after the printing of one page is completed in the print mode. In the toner collecting mode, the toner that is excessively accumulated on the first electrode 21, the toner accumulated in the toner insertion hole 23, and the like are supplied to the toner supply unit 1.
It is provided to recover to zero.

(2) Description of operation in print mode

FIG. 6 shows changes in the potential of each part in the print mode.

Toner supply roller 1 is applied with a periodic voltage having two values, for example, 0V and + 200V. For the first grid electrode 311 of the auxiliary electrode 300, for example,
A constant voltage of + 50V is applied. Second auxiliary electrode 300
A constant voltage of +150 V, for example, is applied to the grid electrode 312.

An on-voltage (for example -100V) and an off-voltage (for example + 300V) are selectively applied to each first electrode 21. The first electrodes 21 are controlled by the dimic scan, and the applied voltage is sequentially turned on at predetermined unit time intervals.

An on-voltage (for example, 0 V) and an off-voltage (for example, -200 V) are selectively applied to each second electrode 22 based on image information. And the first
Only when the applied voltage to both the electrode 21 and the second electrode 22 is the ON voltage, the toner passes through the toner insertion hole 23 located at the intersection of these electrodes, and dot printing is performed.

For the base roller 3, for example, +200
A constant voltage of V is applied. The ultrasonic transducer 50 is the first
On / off control is performed in synchronization with the dynamic scan of the electrode 21.

As shown in FIG. 4, in the slit 321 of the auxiliary electrode 300, the potential difference between the first grid electrode 311 and the second grid electrode 312 causes the first grid electrode 3 to move.
An electric field for moving the toner from the 11 side to the second grid electrode 312 side is always generated.

When the potential of the toner supply roller 1 is 0V, an electric field for moving the toner from the toner supply roller 1 to the auxiliary electrode 300 side is generated between the auxiliary electrode 300 and the toner supply roller 1. Then, due to an electric field for moving the toner from the first grid electrode 311 side to the second grid electrode 312 side, the toner is removed by the auxiliary electrode 300.
Efficiently passes through the slit 321.

When the off-voltage is applied to the first electrode 21, an electric field for moving the toner from the auxiliary electrode 300 to the first electrode 21 side is generated between the first electrode 21 and the auxiliary electrode 30. Then, the toner having passed through the slit 321 of the auxiliary electrode 300 is supplied to the first electrode 21,
Toner is deposited on top.

When the electric potential of the second electrode 22 is higher than the electric potential of the first electrode 21 (when the ON voltage is applied to both electrodes), the toner deposited on the first electrode 21 is transferred to the toner insertion hole 23. Pass through. Then, due to the potential difference between the second electrode 22 and the base roller 3, the toner that has passed through the toner insertion hole 23 is transferred to the recording paper P.

(3) Description of operation in toner recovery mode

In the toner collecting mode, the toner supply roller 1 and the first and second grid electrodes 3 of the auxiliary electrode 300.
11, 312, each first electrode 21 and each second electrode 22
Is applied with a constant voltage that satisfies the relationship shown in the following Expression 3. In Formula 3, V2R is the applied voltage to the second electrode 22, V1R is the applied voltage to the first electrode 21, and VGR
Is the average value of the voltage applied to the auxiliary electrode 300 (the average value of the voltage applied to the first and second grid electrodes 311, 312), and VSR is the voltage applied to the toner supply roller 1.

[0043]

(1) V2R <V1R <VGR <VSR

For example, the applied voltage V2 to the second electrode 22
R is -200V, and the applied voltage V1R to the first electrode 21 is-
100V, the applied voltage to the first grid electrode 311 is 15
0V, the applied voltage to the second grid electrode 312 is 50V,
The voltage VSR applied to the toner supply roller 1 is set to 200V. Average value VGR of applied voltage to auxiliary electrode 300
Is 100V.

In the toner collecting mode, the toner supply roller 1, the first grid electrode 311, the second grid electrode 31.
2. By setting the voltage applied to each first electrode 21 and each second electrode 22 so as to satisfy the relationship of the above mathematical formula 3, the following electric field is generated.

Between the second electrode 22 and the first electrode 21,
An electric field that moves the toner from each second electrode 22 to the first electrode 21 is generated. Each first electrode 21 and auxiliary electrode 30
Between 0 and 0, an electric field that moves the toner from each first electrode 21 to the auxiliary electrode 300 is generated. In the slit 312 of the auxiliary electrode 300, as shown in FIG.
An electric field that moves the toner from the second grid electrode 312 to the first grid electrode 312 is generated. In addition, an electric field that moves the toner from the auxiliary electrode 300 to the toner supply roller 1 is generated between the auxiliary electrode 300 and the toner supply roller 1. Therefore, the excess toner staying in the print head 2 is collected by the toner supply unit 10.

The voltage applied to the toner supply roller 1, each of the first electrodes 21 and each of the second electrodes 22 in the toner collecting mode is applied to them in the printing mode as long as the relation of the above formula 1 can be satisfied. It may be set to one of two binary voltages. This eliminates the need to provide a new power supply circuit for toner recovery.

Also in the toner collecting mode, it is preferable to drive the ultrasonic vibrator 50 in order to increase the toner collecting efficiency. In particular, it is preferable to drive and control the ultrasonic transducer 50 so that the average vibration energy applied to the print head 2 is larger than that in the print mode.

The applied voltage VBR to the base roller 3
Is preferably smaller than the applied voltage V2R to the second electrode 22. The reason for this is as follows. During printing, the applied voltage VBR to the base roller 3 is higher than the applied voltage V2R to the second electrode 22. When the voltage VBR applied to the base roller 3 is made higher than the voltage V2R applied to the second electrode 22 even during the toner recovery, the toner in the toner insertion hole 23 is caused by the potential difference between the second electrode 22 and the base roller 3. The inside of the insertion hole 23 may be moved toward the base roller 3 side. This may occur especially when the ultrasonic transducer 50 is being driven during toner recovery.

The applied voltage VBR to the base roller 3 is set to the second value.
By setting the voltage applied to the electrode 22 to a value smaller than V2R, it is possible to prevent the toner in the toner insertion hole 23 from moving to the base roller 3 side.

Table 1 shows specific examples of the voltage applied to each part in the printing mode and the toner collecting mode.

[0052]

[Table 1]

When the charging polarity of the toner is positive, the magnitude relationship of the applied voltage to each portion in the toner collecting mode is opposite to that described above.

In the above embodiment, the ultrasonic transducer 50
However, the present invention can also be applied to a powder jet image forming apparatus in which the ultrasonic transducer 50 is not provided.

[0055]

According to the present invention, the toner supply electric field can be made constant near each first electrode. Further, the image density does not decrease and the image does not deteriorate.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of a powder jet image forming apparatus.

FIG. 2 is a plan view showing an auxiliary electrode.

FIG. 3 is a cross-sectional view showing an auxiliary electrode.

FIG. 4 is a cross-sectional view for explaining the operation of auxiliary electrodes in the print mode.

FIG. 5 is a cross-sectional view for explaining the operation of the auxiliary electrode in the toner collecting mode.

FIG. 6 is a time chart showing the voltage applied to each part in the print mode.

FIG. 7 is a configuration diagram showing a schematic configuration of a powder jet image forming apparatus developed by the applicant.

FIG. 8 is a plan view showing a print head.

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

FIG. 10 is a cross-sectional view showing a relationship between a grid electrode and a toner collecting roller.

FIG. 11 is a time chart showing changes in the voltage applied to each first electrode.

[Explanation of symbols]

 1 Toner Supply Roller 2 Print Head 3 Base Roller 20 Insulating Layer 21 First Electrode 22 Second Electrode 23 Toner Insertion Hole 300 Toner Auxiliary Electrode 311 First Grid Electrode 312 Second Grid Electrode 321 Slit 322 Bridging Section

Claims (2)

[Claims] 1. A print head, a developer supply roller and a base electrode provided so as to sandwich the print head, the print head being formed on an insulating layer and a surface of the insulating layer on the developer supply roller side. A plurality of first electrodes and a plurality of second electrodes formed on the surface of the insulating layer on the base electrode side are provided, and a matrix electrode portion is formed in the print head by the first electrodes and the second electrodes. A developer insertion hole is formed at each intersection of the first electrode and the second electrode in the print head, and the electric field between the developer supply roller and the first electrode causes the developer supply roller to move from the first electrode to the first electrode. In the powder jet image forming apparatus in which the developer is supplied to the first electrode side and the developer supplied to the first electrode side passes through the developer insertion hole by the electric field between the first electrode and the second electrode. With agent supply roller Is provided with an auxiliary electrode having a plurality of openings for passing a developer, and the auxiliary electrode includes an insulating layer, a first grid electrode formed on the surface of the insulating layer on the developer supply roller side, and the printing of the insulating layer. A second grid electrode formed on the surface of the head side;
A powder jet image forming apparatus, wherein a passing direction of a developer with respect to a developer passage opening is controlled by controlling an applied voltage between a grid electrode and a second grid electrode. 2. An operation mode is provided with a developer recovery mode for recovering a developer in addition to a print mode for performing printing. In the print mode, the developer passage opening of the auxiliary electrode is provided. An electric field for moving the developer from the first grid electrode side to the second grid electrode side causes a second electric field in the developer passage opening of the auxiliary electrode in the developer collecting mode.
The voltage applied to the first grid electrode and the second grid electrode is controlled so that electric fields for moving the developer from the grid electrode side to the first grid electrode side are generated respectively. 1. The powder jet image forming apparatus according to 1.