JPH08118711A - Print head for powder jet image forming apparatus - Google Patents

Abstract

PURPOSE: To provide a print head for a powder jet image forming apparatus in which the ultrasonic oscillation of a matrix electrode section becomes uniform even in the head having a grid electrode. CONSTITUTION: A print head for a powder jet image forming apparatus comprises a grid electrode 30 provided in parallel with the surface of an insulating layer between a first electrode 21 and a developer supply roller 1. The one end of the electrode 30 in a record sheet conveying direction is fixed to a print head body 201 via an ultrasonic oscillator 50, and the other end of the electrode 30 is fixed to the body 201 via a spacer 70, thereby mounting the electrode 30 at the body 201.

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 The applicant has already developed a powder jet image forming apparatus as shown in FIG. This powder jet image forming apparatus has a print head 2 that controls passage of toner charged with a predetermined polarity, for example, negative polarity.
A toner supply roller 1 for supplying toner to the print head 2, a recording paper transport roller 3 for guiding the recording paper P to the print head 2, and a toner transferred onto the recording paper P. And a fixing roller 4 for fixing.

As shown in FIG. 8, the print head 2 includes an insulating substrate (insulating layer) 20 and a matrix-like electrode portion formed in the latter half of the insulating substrate 20 in the recording paper conveying direction (direction indicated by arrow Q). 40 and an ultrasonic vibration generation source 50 provided in the first half of the insulating substrate 20 in the recording paper conveyance direction.

As shown in FIGS. 9 and 10, the matrix-shaped electrode portion 40 has a toner supply roller 1 on the insulating substrate 20.
The plurality of first electrodes 21 formed on the surface of the straw and the plurality of second electrodes 22 formed on the surface of the straw by the recording paper conveyance roller 3 of the insulating substrate 20 are provided. A plurality of first electrodes 21
Further, the plurality of second electrodes 22 form a matrix electrode part. 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.

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.

The recording paper P is moved in the direction perpendicular to the first electrode 21 by the recording paper conveying roller 3 and in the direction in which control by dynamic scanning of the first electrode 21 proceeds (direction shown by arrow Q in FIGS. 8 and 9). Be transported. A voltage of +500 V is applied to the recording paper carrying roller 3. The toner supply roller 1 is grounded and its surface potential is 0V.

The ultrasonic vibration generating source 50 includes a toner insertion hole 2
Ultrasonic vibration is applied to the print head 2 in order to prevent the toner from being clogged in 3 and to allow the toner to smoothly pass through the toner insertion hole 23. The ultrasonic vibration generation source 50 includes four ultrasonic transducers 51, 52, 53, 5
4. The vibration frequency of each ultrasonic transducer 51-54 is about 300-500 KHz.

In the above powder jet image forming apparatus, the toner is supplied from the toner supply roller 1 side to the first electrode 21 by the electric field between the toner supply roller 1 and 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.

[0009]

By the way, the toner is supplied from the toner supply roller 1 to the print head 2 by an electric field (generated by the difference between the potential of the toner supply roller 1 and the potential of the first electrode 21 at the time of off voltage). This is performed by the action of the toner supplying electric field). However, since the outer surface of the toner supply roller 1 is a curved surface, when printing is performed, the 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 toner supply electric field in the vicinity of each first electrode 21 is different. Therefore, the above-mentioned powder jet image forming apparatus has a problem that uneven image density occurs.

Therefore, in order to make the toner supplying electric field in the vicinity of each first electrode 21 constant, the applicant of the present invention has shown in FIG.
As shown in FIG. 1, a print head 1 including a grid electrode 30
00 was developed. This print head 100 is shown in FIGS.
A print head body 10 having the same structure as the print head 2 shown in FIG.
1 and a grid electrode 30 attached to the surface of the print head main body 101 on the toner supply roller 1 side via a spacer 60. The grid electrode 30 is arranged parallel to the print head body 101.

In such a print head 100, the distance between each first electrode 21 of the print head body 101 and the grid electrode 30 is constant. Therefore, by applying a predetermined voltage to the grid electrode 30, an electric field for supplying the toner to the first electrode 21 can be uniformly generated between each first electrode 21 and the grid electrode 30. .

However, in this print head 100, the vibration applied to the print head 100 is transmitted to the grid electrode 30, and this vibration interferes with the vibration applied to the print head 100. There is a problem when vibration is disturbed.

An object of the present invention is to provide a print head in a powder jet image forming apparatus in which ultrasonic vibrations in a matrix electrode portion are uniform even in a print head provided with a grid electrode.

[0014]

A first print head in a powder jet image forming apparatus according to the present invention comprises a plurality of first print heads each having a developer supply portion of an insulating layer formed on the surface of the wrinkle.
A matrix-shaped electrode portion is formed by the electrodes and a plurality of second electrodes formed on the surface of the recording paper conveying portion of the insulating layer, and the developer is inserted into each intersection of the first electrode and the second electrode. In the print head of the powder jet image forming apparatus in which holes are formed, a grid electrode is provided between the first electrode and the developer supply roller in parallel to the surface of the insulating layer, and the grid electrode conveys the recording paper. One end of the grit electrode is fixed to the print head main body via the ultrasonic transducer, and the other end of the grit electrode in the recording paper conveyance direction is fixed to the print head main body via the spacer, so that the grit electrode is attached to the print head. It is characterized by being attached to the main body.

As the spacer, it is preferable to use a material that easily absorbs vibration.

A second print head in the powder jet image forming apparatus according to the present invention comprises a plurality of first electrodes formed on the surface of the developer supplying portion of the insulating layer and a recording paper conveying portion of the insulating layer. In a powder jet image forming apparatus in which a matrix-like electrode portion is formed by a 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 the print head, a grid electrode is provided between the first electrode and the developer supply roller in parallel to the surface of the insulating layer, and both ends of the grit electrode in the recording paper conveyance direction are respectively separated by a spacer. By being fixed to the main body, the grit electrode is attached to the print head main body, and the ultrasonic transducer is arranged so that the print head main body is sandwiched between one spacer and the print head main body. Characterized in that it is fixed to the body.

It is preferable that one spacer that sandwiches the print head main body with the ultrasonic vibrator is made of a material that easily transmits vibration, and the other spacer is made of a material that easily absorbs vibration. .

[0018]

In the first print head of the powder jet image forming apparatus according to the present invention, the grid electrode is provided between the first electrode and the developer supply roller in parallel with the surface of the insulating layer. In the grid electrode, one end of the grit electrode in the recording paper conveyance direction is fixed to the print head body via the ultrasonic transducer, and the other end of the grit electrode in the recording paper conveyance direction is fixed to the print head main body via the spacer. By doing so, it is attached to the print head main body.

In such a print head, the vibration generated by the ultrasonic transducer is separately and independently applied and transmitted to the print head main body and the grit electrode. Therefore, the vibration transmitted to the print head main body is not disturbed by the vibration transmitted to the grit electrode, so that the vibration transmitted to the matrix electrode portion of the print head main body becomes uniform.

In the second print head of the powder jet image forming apparatus according to the present invention, the grid electrode is provided between the first electrode and the developer supply roller in parallel with the surface of the insulating layer. The grid electrode is attached to the print head main body by fixing both ends of the grid electrode in the recording paper conveyance direction to the print head main body through spacers. An ultrasonic transducer is fixed to the print head main body so as to sandwich the print head main body between the spacer and one spacer.

In such a print head, the vibration generated by the ultrasonic vibrator is simultaneously applied to the spacer that sandwiches the print head main body between the ultrasonic vibrator and the print head main body. The vibration applied to the spacer is transmitted to the grit electrode, and the vibration applied to the print head body is transmitted to the print head body. Therefore, the vibration transmitted to the print head main body is not disturbed by the vibration transmitted to the grit electrode, so that the vibration transmitted to the matrix electrode portion of the print head main body becomes uniform.

[0022]

Embodiments of the present invention will be described below.

(1) Description of First Embodiment A first embodiment of the present invention will be described with reference to FIG.

FIG. 1 shows a schematic structure of the print head 200. The print head 200 includes a print head body 20 having the matrix-shaped electrode portions 40 shown in FIGS.
1, an ultrasonic transducer 50 attached to the print head body 201, and a grid electrode 30 attached to the print head body 201.

As the grid electrode 30, the second electrode 22 is used.
A plurality of slits extending in the length direction of the first electrode 21 are formed in a flat plate shape at intervals in the length direction of the first electrode 21.

The front end of the grid electrode 30 in the recording paper conveyance direction (the direction indicated by the arrow Q in FIG. 1) has the ultrasonic transducer 5 at its front end.
The print head main body 201 is fixed to the print head main body 201 via a spacer 70, and the rear end portion in the recording paper conveyance direction is fixed to the print head main body 201 via the spacer 70.
It is attached to 01. As the spacer 70, a material such as resin that absorbs vibration well is used.

In such a print head 200, when a voltage is applied to the ultrasonic transducer 50, the print head main body 201
Vibration can be applied to the grid electrode 30 independently. Then, the vibration applied to the print head main body 201 and the grid electrode 30 transmits these separately.

Therefore, since the vibration applied to the print head main body 201 and the vibration applied to the grid electrode 30 do not interfere with each other, the vibration transmitted to the print head main body 201 is not disturbed. For this reason,
The vibration transmitted to the matrix-shaped electrode section 40 becomes uniform, and an image without density unevenness can be obtained.

(2) Description of Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIG.

FIG. 2 shows a schematic structure of the print head 300. The print head 300 includes a print head main body 30 having the matrix-shaped electrode portions 40 shown in FIGS.
1, an ultrasonic transducer 50 attached to the print head body 301, and a grid electrode 30 attached to the print head body 301.

As the grid electrode 30, the second electrode 22 is used.
A plurality of slits extending in the length direction of the first electrode 21 are formed in a flat plate shape at intervals in the length direction of the first electrode 21. The grid electrode 30 has a front end portion and a rear end portion in the recording paper conveyance direction (direction indicated by arrow Q in FIG. 2).
The print head body 3 via the spacers 71 and 72, respectively.
By being fixed to 01, it is attached to the print head main body 301.

Of the two spacers 71 and 72, the spacer 71 on the front side in the recording paper conveyance direction is made of a material such as aluminum that transmits vibration well, and the spacer 72 on the rear side in the recording paper conveyance direction is used. As the material, a material such as a resin that absorbs vibration well is used.

The ultrasonic transducer 50 is connected to the spacer 71 on the front side in the recording paper conveyance direction so as to be connected to the print head main body 301.
Is fixed to the surface of the print head main body 301 on the side of the recording paper transport roller 3 (see FIG. 7).

In such a print head 300, when a voltage is applied to the ultrasonic transducer 50, the print head main body 301
Vibration is simultaneously applied to the spacer 71. The vibration applied to the print head body 301 causes the print head body 30 to move.
It is transmitted to one matrix electrode portion 40. Spacer 7
The vibration applied to No. 1 is transmitted to the grid electrode 30.

Therefore, since the vibration applied to the print head main body 301 and the vibration transmitted to the grid electrode 30 do not interfere with each other, the vibration transmitted to the print head main body 301 is not disturbed. For this reason,
The vibration transmitted to the matrix-shaped electrode section 40 becomes uniform, and an image without density unevenness can be obtained.

FIG. 3 shows the result of measuring the vibration of the matrix-shaped electrode portion of the print head 2 in which the grid electrode 30 is not provided as shown in FIG.

The measurement conditions are as follows. Four ultrasonic transducers are arranged in a line. The length, width and thickness of each ultrasonic transducer are 50 mm and 4 respectively.
mm, 1 mm, and the width of vibration applied by all ultrasonic transducers is 200 mm. The voltage applied to the ultrasonic transducer is 4
It is 0 Vpp (sine wave). The frequency of the voltage applied to the ultrasonic transducer is 400 KHz, which is the same frequency as the resonance frequency of the ultrasonic transducer. The distance between the ultrasonic transducer and the toner insertion hole 23 closest to it is 5 to 8 mm. The measurement position is the toner insertion hole 23 closest to the ultrasonic transducer 50.
Is near.

FIG. 4 shows the result of measuring the vibration of the matrix-shaped electrode portion of the print head 100 provided with the grid electrode 30 as shown in FIG. The measurement conditions are the same as in the case of FIG.

Comparing FIG. 3 and FIG. 4, it can be seen that the print head 100 provided with the grid electrode 30 has more vibration than the print head 2 not provided with the grid electrode 30.

FIG. 5 shows the print head 2 of the first embodiment of FIG.
00 shows the result of measuring the vibration of the matrix electrode part of No. 00. FIG. 6 shows the print head 300 of the second embodiment of FIG.
The result of measuring the vibration of the matrix-shaped electrode part of is shown.

The measurement conditions are different in the case of FIG. 3 in the following points. That is, only one ultrasonic transducer is provided. The length, width, and thickness of the ultrasonic transducer are 30 mm, 4 mm, and 1 mm, respectively, and the vibration application width is 30.
mm.

As can be seen from the measurement results of FIGS. 5 and 6, the print heads 200 of the first and second embodiments are
It can be seen that in 300, the vibration is not disturbed as compared with the print head 100 in FIG.

[0043]

According to the present invention, it is possible to obtain the print head in the powder jet image forming apparatus in which the ultrasonic vibration in the matrix-like electrode portion is uniform.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a print head of a first embodiment of the invention.

FIG. 2 is a schematic configuration diagram showing a print head of a second embodiment of the present invention.

FIG. 3 is a print head 2 having no grid electrode.
5 is a graph showing a measurement result of vibrations in the matrix electrode part of FIG.

FIG. 4 is a print head 10 provided with a grid electrode.
It is a graph which shows the measurement result of the vibration in the matrix-shaped electrode part of 0.

5 is a graph showing a measurement result of vibration at a matrix-shaped electrode portion of the print head 200 of FIG.

6 is a graph showing a measurement result of vibration at a matrix-shaped electrode portion of the print head 300 of FIG.

FIG. 7 is a configuration diagram showing a schematic configuration of a powder jet image forming apparatus.

FIG. 8 is a schematic perspective view showing a conventional print head.

9 is a plan view showing the matrix electrode part of FIG. 8. FIG.

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

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

FIG. 12 is a schematic configuration diagram showing a print head provided with a grid electrode.

[Explanation of symbols]

 200, 300 Print head 20 Insulating layer 21 First electrode 22 Second electrode 23 Toner insertion hole 30 Grid electrode 50 Ultrasonic transducer

Claims (4)

[Claims] 1. A matrix composed of a plurality of first electrodes having a developer supply portion of an insulating layer formed on a wrinkle surface and a plurality of second electrodes having a recording paper conveying portion of an insulating layer formed on a wrinkle surface. In a print head in a powder jet image forming apparatus in which a strip-shaped electrode portion is formed and a developer insertion hole is formed at each intersection of the first electrode and the second electrode, the first electrode and the developer supply roller are connected. A grid electrode is provided in parallel with the surface of the insulating layer, and one end of the grit electrode in the recording paper conveyance direction is fixed to the print head body via an ultrasonic transducer. The print head in a powder jet image forming apparatus, wherein the grit electrode is attached to the print head main body by fixing the other end of the print head main body via a spacer. 2. The print head in a powder jet image forming apparatus according to claim 1, wherein the spacer is made of a material that easily absorbs vibration. 3. A matrix composed of a plurality of first electrodes having a developer supply portion of an insulating layer formed on the wrinkle surface and a plurality of second electrodes having a recording paper conveying portion of the insulating layer formed on the wrinkle surface. In a print head in a powder jet image forming apparatus in which a strip-shaped electrode portion is formed and a developer insertion hole is formed at each intersection of the first electrode and the second electrode, the first electrode and the developer supply roller are connected. A grid electrode is provided in parallel with the surface of the insulating layer, and both ends of the grit electrode in the recording paper conveyance direction are fixed to the print head main body through spacers, respectively, so that the grit electrode is attached to the print head main body. Is attached to the print head body with one spacer, and the ultrasonic transducer is fixed to the print head body in the powder jet image forming apparatus. Kick the print head. 4. A material that easily transmits vibration is used as one spacer that sandwiches the print head main body with the ultrasonic transducer, and a material that easily absorbs vibration is used as the other spacer. The print head in the powder jet image forming apparatus according to claim 3.