JPH02266370A - Electrostatic recorder - Google Patents

Abstract

PURPOSE:To perform uniform printing with high density by applying a first voltage of a prescribed frequency to a control electrode and applying a second voltage of a higher frequency than the prescribed frequency per printing information to a segment electrode plural times. CONSTITUTION:A toner carrier 12 holding a toner layer on its surface carries toner T along a prescribed path. A common electrode body 8 is rotatably disposed on the opposite side to the toner carrying surface of the toner carrier 12 and a spiral electrode 9 is provided on its periphery. On the other hand, a signal electrode body 3 is oppositely disposed on the toner carrying surface of the toner carrier 12 and constituted of plural segment electrodes 3b1 and 3b2, while control electrodes 13a to 13c are provided inside of the toner carrier 12. The first voltage of the prescribed frequency is applied to the control electrodes 13a to 13c and the second voltage of higher frequency than the prescribed frequency per printing information is applied to the segment electrodes 3b1 and 3b2 plural times, so that the toner T on the toner carrier 12 can be transferred to recording material P fed between the toner carrier 12 and the signal electrode body 3. The uniform printing with high density can thus be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a recording device, and particularly to an electrostatic recording device that directly prints an image on plain paper.

[Prior art and its problems]

Powder contrast is known as an electrostatic recording device that directly records images on plain paper. This device has a multi-needle electrode such as a multi-stylus and a drum-shaped counter electrode holding toner arranged opposite each other, and plain paper is conveyed between the two electrodes. Then, when a predetermined voltage is applied between the two electrodes according to the video signal to generate a local electric field between the two electrodes, the charged toner is attracted to the plain paper according to the video signal.
This is a device that thermally fixes this toner onto plain paper to form an image.

However, the structure of the multi-needle electrode is extremely complicated, and moreover, the multi-needle electrode is expensive. In addition, when checking the adhesion status of toner printed on paper, it is found that a large amount of toner is adhering only in the center of the fine adhesion area, and less toner adhesion is observed in the periphery of the adhesion area, and vice versa. In some cases, the toner could not be applied uniformly and sufficiently to all the adhesion areas.

[Object of the Invention] In view of the above-mentioned drawbacks of the conventional art, the present invention achieves high-density and uniform printing by depositing uniform and sufficient toner over the entire toner deposition area, and also uses an expensive multi-needle electrode. An object of the present invention is to provide an electrostatic recording device that can perform printing without any problems.

[Key points of the invention]

According to the present invention, the above-mentioned object includes a toner conveying body that carries a toner layer on its surface and conveys the toner along a predetermined path; a common electrode body provided with a spiral electrode, a signal electrode body formed of a plurality of segment electrodes and disposed opposite to the toner carrying surface of the toner conveying body, and a control n-electrode provided inside the toner conveying body. by applying a first voltage with a predetermined frequency to the control electrode and applying a second voltage with a higher frequency than the predetermined frequency to the segment electrode multiple times per print information, This is achieved by providing an electrostatic recording device that transfers toner onto a recording material fed between the toner conveying body and the signal electrode body.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a schematic cross-sectional view of an electrostatic recording device according to an embodiment. In the figure, an electrostatic recording apparatus 1 is composed of a developing device 2, a recording head 3, a static elimination brush 4, a standby roll 5, a fixing roll 6, conveyance guide plates 7a, 7b, 7C1 conveyance bell) 7b'. The standby roll 5 has an internal heater (not shown), and is a roll that conveys the paper in the direction of arrow "A" at a predetermined timing and removes moisture contained in the paper.

The static elimination brush 4 is a brush that removes electrical charges generated on the paper during conveyance. The conveyance guide plates 7a, 7b, and 7c are members that guide the conveyance of the paper in the direction of arrow "A" and are made of an insulating material. The conveyor belt 7b' rotates in the direction of the arrow "c" and is a so-called air suction belt for conveying the paper with toner attached to the upper surface while sucking it downward so as not to contact the conveyance guide plate 7b side, as will be described later. It is.

The fixing roll 6 is a heating roll 6 with a built-in heater 6a'.
This roll is composed of a pressure roll 6b that is in pressure contact with a heating roll 6a, and fixes unfixed toner onto the paper using heat and pressure.

The developing device 2 has a developing roll 8 provided below a developing container 2', and a unipolar, one-component, highly magnetic toner T is stored in the developing container 2'. Further, at one end of the developer container 2', a blade 2a is formed to regulate the thickness of a toner layer adhering to a film (insulating film) to be described later. The developing roll 8 is fixed to a rotating shaft 8a, and includes a magnet roll 8b in which north poles and south poles are alternately formed, and a magnet roll 8b.
The periphery of the developing roll 8 is covered with a fixed sleeve 19 and a film (insulating film) 12 whose structure will be described in detail later.The zero-rotation shaft 8a is a drive mechanism (not shown). This is indicated by the arrow in the same figure.”
The sleeve 8c rotates at high speed in the direction of the mouth.A spiral linear electrode, which will be described later, is embedded in the circumferential surface of the sleeve 8c.

The recording head 3 is positioned directly below the developing roll 8 and faces the film 12 through the gap between the transport guide plates 7a and 7b.
It is located in FIG. 3 shows a perspective view of the recording head 3 and the developing roll 8.

The recording head 3 has a large number of segment electrodes 3b-1, 3b-2, . . . with an insulating plate 3a in between, and the segment electrodes 3b-1, 3b-2, . stomach"
direction) and the direction (main scanning direction) perpendicular to the main scanning direction. Each segment electrode 3b-1, 3b-2, . . . has a corresponding switch 3cm1.3cm2, .
is connected to the high voltage power supply 3d via the switch 3cm1.
Segment electrode 3b corresponding to the closing of 3cm2,...
-1, 3b-2, . . . apply a high voltage from the high voltage power supply 3d. Note that the segment electrodes 3b-1, 3b-2,...
Application of a high voltage to is performed at a timing that will be described in detail later.

On the other hand, as shown in the figure, linear electrodes 9 are spirally formed on the circumferential surface of the sleeve 8c, and the linear electrodes 9 are buried at predetermined intervals without contacting each other. Further, the linear electrode 9 is grounded via a grounding wire 9'.

Further, the film 12 disposed to cover the lower part of the developing roll 8 has both ends stretched over the aforementioned fixed sleeve 19.
Directly below the sleeve 8c within the film 12 is a control type Ffi.
i 13 a to 13 c are formed parallel to the main scanning direction. One end of the control electrodes 13a to 13c is connected to the high voltage power supply 3d via a switch 10.

FIG. 1 is a schematic cross-sectional view showing the detailed structure of the recording head 3, developing roll 8, and film 12. The film 12 is made of polyethylene terephthalate (with a thickness of several μm).
As described above, the sleeve 8c is covered with the lower surface of the sleeve 8c made of PET. Further, control electrodes 13a to 13c are formed in this film 12 as described above, and the control electrodes 13a to 13c are formed as described above.
There are gaps of a predetermined width (for example, 0.1 m in this embodiment) between a and 13b and between 13b and 13c. This control electrode 13ax13c is connected to the high voltage power source 3d via the switch 10 as described above (as shown in FIG. 3), but in FIG. 11 it is shown as the output voltage source 11 to the control electrodes 13a to 13c. There is.

3D in FIG. 1 also shows the high voltage as an output voltage source including the source 3d and the corresponding switches 3C-1 and 3C-2.

Further, as the toner T adhering to the lower surface of the film 12 shown in the figure is rotated toward the "opening" direction of the developing roll 8, the toner T in the developing container 2' is transferred to the magnetic poles of the N and S poles of the magnet roll 8b. The film was attached to the fixed sleeve 19 by the magnetic force created by the film 12, and further moved along the lower surface of the film 12 to the printing section F.

In this embodiment, the dimensions and thicknesses of each member, toner layer, etc. in the printing section F are set as follows.

First, segments Ti8i3b-1, 3b-2,...
The distance from the tip of the linear electrode 9 to the linear electrode 9 is 200 Im. The width i, which is the sum of the thickness of the toner T and the thickness of the film 12, is 65 μm. Segment electrodes 3b-1, 3b-2,
The tip width w1 of ... and the width W2 of the linear electrode 9 are both 0.
It is 1 Peng. Further, as the paper P, a paper having a thickness L of 86 μm is used.

In addition, if each dimension is set as above, the transport guide Fi7
The distance G between the upper surface Pa of the paper P conveyed through a and 7b and the lower surface t# of the toner layer is set to 49 μm.

FIG. 4 is a diagram showing the positional relationship of the linear electrode 9 moving with respect to the segment electrodes 3b-1, 3b-2, . . . .

In the figure, the linear electrode 9 moves in the direction of arrow "2". That is, when the sleeve 8c rotates in the "mouth" direction, the linear electrode 9 moves from left to right (in the direction of arrow "2") in the drawing.

In addition, Lst shown in the same figure is segment electrode 3b-1, 3b.
LLsE has an effective length of -2, .
... indicates the length of the segment electrode 3b-1, and Hsx is the segment electrode 3b-1.
, 3b-2, . . . in the sub-scanning direction, and LsP! , twA-shaped electrodes 9 are arranged at intervals in the scanning direction.

In the electrostatic recording apparatus 1 configured as described above, in this embodiment, the control voltage is output from the output voltage source 11 to the control electrodes 13a to 13c at a constant cycle, and the control voltage is output from the output voltage source 3D to the segment electrodes. 3b-1, 3b-2,...
Good printing is achieved by using a predetermined high frequency signal to output the high voltage to the pulse voltage.

FIG. 5(a) shows the output voltage source 3D to the recording electrode 3b-1.
, 3b-2, . . . , 3b-2, . The control voltage shown in (b) of the same figure is the output time PWl
is the voltage of the control electrode 13 at a constant period (1/f).
a ” 13 It is constantly output to c.

Further, the output voltage shown in (a) of the same figure is applied to the corresponding recording electrodes 3b-1, 3b-2, . . . at the timing when the switches 3C-1, 3cm2, .
(a) in the figure is the voltage applied to “0”→″
1"→"1". More specifically, when the video data is "1", a control circuit (not shown) switches the switch 3cm 1.3C- as shown in FIG.
2,... is turned on with a period of 1/rz (closing time P-2),
Control is performed to repeat off twice. As a result, the corresponding recording electrodes 3b-1, 3b-2, . . .
) A pulse signal with a period t/rt shorter than the period 1/fI is applied.

Therefore, as shown in FIG. 6, the printed portion F corresponding to the switch that repeats on and off in response to video data "1" is provided between the segment electrodes 3b-1, 3b-2, . . . and the linear electrode 9. An electric field E shown by a dotted line is formed through the gap between the control electrodes 13a and 13b. In addition, 3d' shown in the figure indicates a positive high voltage applied to the recording electrodes 3b-1, 3b-2, etc., and 11' indicates a positive high voltage applied to the control electrodes 13a, 13b. .

On the other hand, the paper P is fed by the standby roll 5 to the printing section F via the neutralization brush 4 and the conveyance guide plate 7a. The blade 2a removes the toner T in the developer container 2 from the bottom surface of the film 12.
The toner T regulated to a predetermined thickness is adhered thereto, and the toner T is conveyed to the printing section F. The toner T adhering to the lower surface of the film 12 adheres to the upper surface of the paper P by the Coulomb force caused by the electric field. Moreover, at this time, the high voltage applied to the segment electrodes 3b-1, 3b-2, . . . and the control voltage outputs outputted to the control electrodes 13a to 13c are in the state shown in FIG. The toner T adheres to the paper P sufficiently and evenly. Also, the seventh
As shown in the figure, segment electrodes 3b-1, 3b-2,
... and the control electrodes 13a and 13 arranged between the linear electrodes 9
b, the gap between 13b and 13c is extremely narrow, and as mentioned above, the width of segment electrodes 3b-1, 3b-2,...
Same as m). Therefore, as shown in FIGS. 1 and 7, the electric field E is applied to the segment electrodes 3b-1, 3b-2, . . .
The electrodes 9 and 9 are formed in high density only at the crossing opposing portions of the linear electrodes 9.

This cast state also allows the toner T to adhere with a higher density.

Next, the inventor of the present invention conducted the following measurements to confirm the effects of the present invention.

First, in order to compare with the present invention, measurement results of a comparative example are shown.
Although the comparative example used here has a different configuration from the conventional powder control using multi-needle electrodes, the recording and control electrodes are connected at the same timing as shown in Figure 8 (a) and (b). This is an example in which a voltage is applied.

The measurement conditions are shown below.

Recording electrodes (segment electrodes 3b-1, 3b-2...)
The distance between the electrode 9 and the linear electrode 9 is 200 um.

The thickness l, which is the toner layer plus the thickness of the sleeve 18, is 65μ.
Let it be m.

The width W1 of the tip of the recording electrode and the width W2 of the linear electrode 16 are both 0.1 m.

The thickness t of the paper P is 86 μm plain paper.

The high voltage output to the recording electrode is 800 cm, and the pulse width Pw3 is 1 m1 as shown in Fig. 8 (a) and (b).
, c, the pulse frequency 13 is 500 Hz.

The high voltage output to the control electrode is +800cm, the same as the high voltage output to the recording electrode, and the pulse width (P Wi )
1 m5ec, pulse frequency (f3) 500Hz
Use.

Note that the toner T is a unipolar, one-component high/low magnetic toner.

When printing was performed under the above conditions, the printed dots were clear but uneven in density and had a diameter of approximately 0.1M, which was measured using a microdensitometer (M, D).

The concentration according to M) was 1.0.

Next, as shown in FIGS. 5(a) and 5(b), the segment electrodes 3b-1, 3b-2, ... and the control B electrode 13
The voltage application to a to 13c was controlled, and the other measurements were performed under the above measurement conditions. In this case, segment electrode 3b
The voltage applied to -1, 3b-2, ... is a high voltage soo
v, the pulse width PW2 was lOOμSEC, and the pulse frequency was 5Kz. The timing of the voltage applied to the control electrodes 13a to 13c is the same as in (b) of FIG.
In FIG. 3), the pulse width PWl is 1 mt*c, and the pulse frequency r is 500 Hz.

As expected, high density and uniform printing with a diameter of 0.1+n was achieved, and the density measured by a microdensitometer was improved to 1.2.

As described above, according to this embodiment, the toner printed on the paper P is clear and uniform.

Note that the specific numerical values used in the above measurements were specifically set in order to perform the above measurements, and it goes without saying that the present invention is not limited to the setting of the above numerical values.

〔Effect of the invention〕

As described above in detail, according to the present invention, high density printing is possible, and moreover, it is possible to print uniformly and obtain an image with excellent print quality.

Furthermore, since multi-needle electrodes such as an expensive multi-stylus are not used, the cost of the device can be reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the main parts of an electrostatic recording device according to an embodiment. FIG. 2 is a schematic sectional view of an electrostatic recording device according to an embodiment. FIG. 3 is a perspective view of segment electrodes and a developing roll. The figure shows the arrangement relationship between the segment electrodes and the linear electrodes. Figure 5 is a time chart showing the timing of applying the output voltage to the segment electrodes and control electrodes in this example. Figure 6 shows the control electrodes and the segment electrodes. 7 is a configuration diagram showing the arrangement relationship between segment electrodes and linear electrodes between control electrodes, and FIG. 8 shows the timing of application of output voltage by a conventional electrostatic recording device. This is a time chart. DESCRIPTION OF SYMBOLS 1... Electrostatic recording device, 2... Developing device, 3... Recording head, 3a-1, 3b-2,... Segment electrode, 3cm1.3cm2,... Switch, 3d... High voltage power supply, 4... Static elimination brush, 5... Standby roll, 6... Fixing roll, 7a to 7c... Conveyance roll, 7b'... Conveyance belt, 8... Developing roll, 8c. ... Sleeve, 9... Linear electrode, 3D, 11... Output voltage source, 12... Film, 13a-13c... Control electrode.

Claims (1)

[Claims] A common toner transporting body that carries a toner layer on its surface and transports the toner along a predetermined path, and a common spiral electrode that is rotatably disposed on the opposite side of the toner carrying surface of the toner transporting body and provided on its peripheral surface. It has an electrode body, a signal electrode body formed of a plurality of segment electrodes disposed opposite to the toner carrying surface of the toner conveying body, and a control electrode provided inside the toner conveying body, and the control electrode is provided with a predetermined frequency. By applying a first voltage and applying a second voltage having a frequency higher than the predetermined frequency to the segment electrode multiple times per print information, the toner on the toner transport body is transferred to the signal electrode and the toner transport body. An electrostatic recording device that transfers onto a recording material that is transported between the bodies.