JPS62127249A - Electrostatic accelerating type ink jet recorder - Google Patents

Abstract

PURPOSE:To prevent a spread of ink to form an extremely small dot and an accurate image, by a method wherein high-voltage pulse is successively applied to back plates consisting of numbers of electrodes insulated from one another. CONSTITUTION:Back plates 32 in an ink control portion 2 consists of number of electrodes electrically insulated from one another. High electric field is formed only between a charge injection electrode 16 selected by means of irradiation to a photoconductor 18 and the back plate 32 to which high-voltage pulse is applied from a high-voltage pulse generating circuit 34, thus flying an ink Q from an ink injection nozzle P to form a recording dot on a recording medium 3. In this case, an ink drip cannot fly to the adjacent back plates 32 with no high-voltage pulse applied. In this manner, prevention of spread of the ink can result in an extremely small dot and an accurate image.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to an electrostatic acceleration type inkjet recording device suitable for, for example, a copying machine.

(Technical Background of the Invention and Problems Thereof) Inkjet recording apparatuses that form recording dots by jetting liquid ink onto a recording medium have been known.

This inkjet recording II has the advantage of being less noisy than other recording apparatuses and does not require processes such as development and fixing, and is attracting attention as a plain paper recording technology.

Among these inkjet recording devices, those called slitjet recording devices in which the ink jetting ports are formed in a slit shape are prone to ink clogging due to the slit-shaped ink jetting ports. It is hoped that this technology will be put to practical use in copying machines because of the fact that it is possible to do so.

This electrostatic acceleration type inkjet recording device using the slitjet recording method has a width of about 100mm and a length of 200mm.
In the longitudinal direction of the slit-shaped ink jet port of about m+, 8
A large number of charge injection electrodes arranged at a ratio of about 1/2,
It is equipped with a back electrode provided opposite to the charged incoming currents tIi, t; and the slit-shaped ink ejection ports, and means for applying a high voltage pulse between these two currents Ii in response to a recording signal. be.

Then, the charged oil-based ink in the portion to which a high voltage is selectively applied is attracted toward the back electrode by electrostatic force, forming ink dots corresponding to the distribution signal on the recording medium placed between both electrodes. This is what I did.

In such a recording device, a high voltage pulse generation circuit for selectively applying a high voltage pulse to each of a large number of charge injection electrodes according to recording information is not provided for each charge injection electrode. There was a risk that the equipment would become complicated. Furthermore, connecting a plurality of switching circuits to each of a large number of charge injection electrodes has the problem of complicating the wiring connections. Therefore, the present inventors previously proposed in Japanese Patent Application No. 59-108792 that a photoconductor whose electrical resistance changes depending on the intensity of received light is charged;
↑It is integrated on the same substrate as the large electrode and connected to each of the 11 charge injection electrodes, and is selected as the charge injection electrode by the switching action of the photoconductor when a light signal corresponding to the recording signal is irradiated to these photoconductors. We proposed a device that applies high voltage pulses.

However, in this device, since the back electrode is continuous in the longitudinal direction of the slit-shaped ink jet port, the selected charge injection I! There is a problem in that the flying ink spreads from the pole toward the back surface 1tj, and an ink dot wider than the width of the charge injection electrode is formed on the recording medium, resulting in loss of definition of the recorded image.

[Purpose of the invention]

The present invention was made based on the above problem, and its purpose is to facilitate the application of a high voltage pulse corresponding to a recording signal to the charge injection electrode \ without changing the structure to IB. Another object of the present invention is to provide an electrostatic acceleration type inkjet recording device that can obtain fine recorded images.

[Summary of the invention]

The present invention provides a plurality of 1! which are disposed so that their tips face a slit-shaped ink ejection port, and which come into contact with recording ink and inject charge into the ink. A high voltage pulse is applied between a charge injection electrode and a back electrode provided opposite to the ink jetting port, and the ink jetted from the ink jetting port is injected into the ink jetting port according to the voltage change between the two electrodes. Electrostatic acceleration type inkjet recording that forms recording dots by depositing on a recording medium interposed between electrodes! ! Among the devices, in particular, the plurality of charge injection electrodes are commonly connected to a first common electrode via a photoconductor whose resistance value changes depending on the amount of light received, and the second common electrode is connected via a fixed resistor. By connecting to the electrode and applying first and second potentials to the first and second common electric bridges, respectively, and in this state, irradiating the photoconductor with an optical signal corresponding to the recording signal, the electric charge is generated. In a device that applies a high voltage pulse between an injected charge and a back electrode, a plurality of front two back electrodes are provided corresponding to each of the charge injection electrodes, and a voltage is sequentially applied to the plurality of back electrodes. It is characterized by providing means for applying pulses.

(j!light effect) According to the present invention, the back electrode is composed of a large number of electrically insulated electrodes, and high voltage pulses are sequentially applied to these back electrodes. A strong electric field is formed only between the charge injection electrode selected by irradiating the conductor with light and the back electrode to which the high voltage pulse was applied, and the back electrode adjacent to the back electrode to which the high voltage pulse was applied No flying of ink droplets occurs. Therefore, according to the present invention, the spread of ink can be suppressed and the pixel can be made extremely small, so that a fine image can be obtained.

(Example of the invention) Hereinafter, one embodiment of the present invention will be described based on the drawings.

As shown in FIG. 1, the inkjet recording Ha according to this embodiment arranges an ink ejection section 2 and an ink control section 2 facing each other, and makes ink droplets fly onto a recording medium 3 that moves between the two. A recorded image is formed on the recording medium 3 by using the recording medium 3.

The ink ejection part 1 has a wedge-shaped edge on the tip side where the slit-shaped ink ejection opening P is formed to facilitate adjustment of the ink ejection position W1, and a plate-shaped electrode assembly 11. and an ink guide member 12 provided on the upper surface of the electrode assembly 11 so as to cover the surface on the side of the ink ejection port P. The ink guide member 12 has an ink reservoir 13 containing liquid ink Q at its base end, and forms an ink flow path R having the same width as the slit and a minute thickness from the ink reservoir 13 to the ink jet port P. In order to achieve this, a groove of minute depth is formed opposite the electrode assembly 11.

The electrode assembly 11 includes a plurality of linear charge injection electrodes 16 extending from the tip end to the base end of the substrate on the upper surface of a substrate 15, such as a glass plate, which has excellent electrical insulation and is not easily affected by the oil-based ink Q. is arranged on the upper surface of the base end of the substrate 14 at a predetermined interval from the base end of each charge injection electrode 16, and the base ends thereof are commonly connected. ! Two first common electrodes 17 are formed, and these first common electrodes 17 and each charge injection electrode 16 are connected by a photoconductor 18.

The ink guiding member 12 is made of a material having excellent electrical insulation properties, for example, ceramic, and is provided on a surface facing the tip of the charge injection electrode 16 in the vicinity of the ink ejection port P in a direction perpendicular to the chargeable incoming current 1i16. An extending second common electrode 19 is arranged.

The charge injection electrode 16 and the first and second common electrodes 17
．． 19 can be formed by vacuum-depositing, for example, gold chrome on the substrate 15 and the ink guiding member 13, and then performing a normal etching process. The width of the second common electrode 19 is such that the electrical resistance between the charge injection electrode 16 and the second common electrode 19 when the photoconductor 18 receives light when the ink flow path R is filled with the liquid ink Q is determined. The resistance value is determined in consideration of the specific resistance value of the ink so that it is within the range of the resistance value at the time of sale, preferably an intermediate value. In addition, 111 bodies of light 18
Hydrogenated 7-molyph 7-silicon is suitable as the
It can be formed on the substrate 15 by a CVD method.

The first common electrode 17 is connected to the negative electrode side of a DC power supply 21, which is means for applying a first potential. Further, the second common electrode 19 is connected to the positive electrode side of a DC power supply 22, which is means for applying a second potential. The positive electrode of the DC power source 21 and the negative electrode of the DC power source 22 are commonly connected and grounded.

On the other hand, Ink 111WJ Department? - is constructed by disposing a plurality of back electrodes 32 on a substrate 31 so as to face each of the charge injection electrodes 16, and attaching an upper plate 33 to the upper surface. For example, every eight back electrodes 32 are commonly connected, and these eight common connections are connected to eight output terminals of the high voltage pulse generating circuit 34, respectively.

The high voltage pulse generation circuit 34 is configured as shown in FIG. 2, for example. That is, the reference clock signal from the clock oscillator 41 is counted by the 3-bit output counter 42. Then, the 3-bit output of the counter 42 is input to the decoder 43. The decoder 43 outputs a pulse signal from an output terminal corresponding to input data.

That is, the eight output terminals of the decoder 43 sequentially output pulse signals with slightly shifted timing. The pulse signal from the decoder 43 is converted into a high voltage pulse in the amplifier 44, and this high voltage pulse is supplied to the back electrode 32 described above.

Next, the operation of the recording apparatus according to this embodiment configured as described above will be explained.

l! The potential of the charge injection electrode 16 is set to V! , when the potential of the back electrode 32 is Vo, the potential difference Vx between both electrodes is Vx =
Vo −V r ·ll).

Also, the first common l! The potential of the pole 17 is Vp (<OV),
The potential of the second common layer ti19 is VN (>OV), the resistance value of the photoconductor 18 is Rx, the resistance value of the liquid ink Q between the charge injection electrode 16 and the second common electrode 19 (fixed resistor ) is Rc, the potential V+ of the charge injection electrode is V+ = Vp - (VP-VN) Rx / (Rx + Rc).
...(2) It is shown as follows.

Therefore, for example, the resistance value Rp of the photoconductor 18 when irradiated with light and the resistance value Rp of the photoconductor 18 when not irradiated with light are
resistance (!IRo and the resistance of the fixed resistor 1ifl Rc
In the darkness, Rp <RecRo ・13)
If the following relationship is satisfied, the potential V+p of the charge injection electrode 16 when the photoconductor 18 receives light and the potential V+o of the charge injection electrode 16 when the photoconductor 18 receives light are respectively V+p Δh circle=Vp
... (4) V+ o 4
Vs...15).

In other words, as shown in FIG.
~VN.

On the other hand, high voltage pulses having a frequency sufficiently higher than the frequency of the optical signal are sequentially applied to the back electrode 32. If the potential Vo of the back electrode 32 in a state where no high voltage pulse is applied is OV and the peak value of the high voltage pulse is VA, the potential difference Vx between the charge injection electrode 16 and the back electrode is as shown in FIG. As shown in FIG. 3, the maximum voltage is reached when the photoconductor 18 is irradiated with an optical signal and a voltage pulse is applied to the back electrode 32. The potential difference Vx between both electrodes at this time is Vx = Vp - VN - VA - (6)
becomes. Therefore, as shown in FIG. 3, the threshold 1iVth at which ink droplets start flying is -VA > Vt
If the distance between the charge injection electrode 16 and the back electrode 32 is set so that h>Vp VN VA (7), the distance between the charge injection electrode 16 to which the optical signal is incident and the back electrode opposite thereto Only when a high voltage pulse is applied to 32, its back surface 1!, as shown in FIG. An ink droplet is ejected toward the electrode 32 and other adjacent back electrodes 32
It does not fly to. Therefore, according to this device, it is possible to prevent the ink droplets from spreading, so that fine images can be formed.

The inventors conducted the following tests on this recording device.

That is, a glass plate is used as the substrate 15, and this substrate 1
A metal chrome layer of 1,600 mm thick was formed on the 5th layer by vacuum deposition, and etched to a width of 60 m and an array pitch of 120 mm. charge injection electrode 16, and a first common 1! separated from this by a distance of 60 points! [17 was formed. A photoconductor 18 made of a hydrogenated amorphous silicon layer having a thickness of 1.5 mm was formed between the two by CVD. The resistance value Rp of the photoconductor 18 when the portion of the photoconductor 16 on the obtained electric rod assembly is irradiated with light of 1001 ux is +, (ix
10”Ω, resistance when sold out [I Ro is 5.6X 1
It was 0'Ω.

On the other hand, using a ceramic plate as the ink guide member 12,
A second common electrode having a width of 3111 mm was formed by vacuum evaporating metallic chromium to a thickness of 1,600 mm and etching it. The liquid ink used had a specific resistance of about 1090·crn.

-200 V is applied to the first common electrode 17 and +200 V is applied to the second common electrode 19, and the photoconductor 18 is irradiated with a red light emitting diode (TLR108: manufactured by Toshiba Corporation) to inject charges. When I measured the potential of -20
It was 0■. In addition, when the potential of the charge injection electrode 16 was measured with the red light emitting diode turned off, it was found to be +200.
It was V.

On the other hand, the back electrode 32 was covered with a polyurethane resin film. Using 801J11 nickel wires, they were lined up and molded with epoxy resin mixed with quartz powder to integrate them. This back electrode 32 has one end of nickel wire arranged in a straight line at a ratio of 8/M in epoxy resin mixed with quartz powder. Is this the backlight? 113
2 were commonly connected every eight, and eight lead terminals were pulled out.

The same voltage as described above was applied to the first and second common electrodes 17 and 19, and a high voltage pulse with a peak value of +700 V and a pulse width of 1 m5ec was applied to the back electrode 32 in sequence to the eight lead terminals. . Charge injection electrode 16 and back electrode 32
When the recording paper was slowly moved between the
In synchronization with this, pixels were formed on the recording paper. This dot was extremely minute.

Furthermore, a copying machine as shown in FIG. 5 was constructed using the above-mentioned apparatus.

That is, light from a light source 51 is reflected by a copy document (not shown) set on a document table 52 as shown by the dotted line arrow in the figure, and a self-focusing optical fiber array (Selfoc lens: manufactured by Nippon Sheet Glass Co., Ltd.) is used. 53 to the photoconductor of the ink jetting section 1.

On the other hand, the recording paper 3 housed in the recording paper storage case 54 is
The ink is sequentially fed by a roller 55 and guided between the ink ejection part and the ink e+m+ part 2 via a guide 56 and a roller 57.

When voltages similar to those described above were applied to the first and second common 'R' electrodes and the back electrode, a negative image was formed on the recording paper. Furthermore, when the chronicity of the voltage applied to the first and second common electrodes was reversed, a positive image was obtained.

The recording paper 3 is transferred to the roller 58. Case 6 via guide 59
It was made to lead to the outside of 0. The obtained copied image was extremely lI[l and of good image quality.

Note that the photoconductor is a hydrogenated amorphous silicon pond,
Selenide alloys such as selenium-tellurium, photoconductive inorganic compounds such as zinc oxide and cadmium sulfide, photoconductive compositions comprising powders of these photoconductive compositions and polymer compounds, copper phthalocyanine and birylene compounds. Organic photoconductive compounds, such as organic photoconductive compounds, and photoconductive compositions containing a photoconductive compound and a compound having a charge transport function may also be used.

Furthermore, as the substrate for supporting the charge injection electrode, the first common electrode, and the photoconductor, materials with excellent electrical insulation properties are preferable, and in addition to the glass used in this example, alumina, sapphire, quartz, etc. is available.

Further, the present invention is configured to guide reflected light from a copy document to a photoconductor through a color filter, and if each of a plurality of electrostatic acceleration type inkjet recording devices is filled with ink of a different color, color It can also be applied to devices that copy images. Furthermore, when combined with an LED array, it can be used as a recording device such as a facsimile machine or a word processor, or an output terminal device such as a computer.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view of the main parts of an electrostatic acceleration inkjet recording device according to an embodiment of the present invention, FIG. 2 is a block diagram of a high voltage pulse generation circuit in the same device, and FIG. FIG. 4 is a waveform diagram to explain the operation of the device, FIG. 4 is a plan view to explain how recording dots are formed in the device, and FIG. 5 is a cross-sectional view showing an example in which the device is applied to a copying machine. 11... Electrode assembly, 12... Ink guide section, 13... Ink reservoir, 15.31... Substrate, 16... Charge injection 1ei, 17... First common electrode , 18... photoconductor, 19... second common 1i1
．． 21.22...DC power supply, 32...Back electrode, 3
3... Upper plate, 34... High voltage pulse generation circuit, 52
... Document table, 53 ... Self-focusing optical fiber array, P ... Slit-shaped ink jetting port, Q ... Liquid ink. Applicant's agent Patent attorney Takehiko Suzue 0 Management 〉〉〉 −, Kame

Claims (5)

[Claims] (1) A plurality of charge injection electrodes that are disposed so that one end faces the slit-shaped ink jetting port and that contact recording ink to inject charge into the ink, and a plurality of charge injection electrodes that are connected to these charge injection electrodes. a photoconductor whose resistance value changes depending on the amount of light received; a first common electrode connected to the charge injection electrode via the photoconductor; and a first common electrode connected to the first common electrode.
a fixed resistor connected to the plurality of charge injection electrodes; a second common electrode connected to the charge injection electrode via the fixed resistor; means for applying a second potential to the electrode; a back electrode provided opposite to the ink ejection port; means for applying a third potential to the back electrode; means for irradiating the photoconductor with light, the ink jetted from the ink jetting port in response to a voltage change between the charge injection electrode and the back electrode caused by the irradiation of light onto the photoconductor. In an electrostatic acceleration type inkjet recording device in which recording dots are formed by depositing on a recording medium interposed between electrodes, a plurality of said back electrodes are arranged corresponding to each of said charge injection electrodes, and An electrostatic acceleration inkjet recording device characterized by comprising means for sequentially applying voltage pulses to the plurality of back electrodes. (2) The electrostatic charge according to claim 1, wherein the means for irradiating the photoconductor with the optical signal is a mechanism that irradiates the photoconductor with reflected light from a copy original. Accelerated inkjet recording device. (3) The means for sequentially applying voltage pulses to the back electrode applies a high voltage pulse signal to the back electrode with a cycle sufficiently shorter than the irradiation cycle of the optical signal irradiated to the photoconductor. An electrostatic acceleration type inkjet recording apparatus according to claim 1, characterized in that: (4) The electrostatic acceleration type inkjet recording apparatus according to claim 1, wherein the first potential and the second potential have opposite polarities. (5) The electrostatic acceleration type inkjet recording apparatus according to claim 1, wherein the fixed resistor is the recording ink.