JPH1067111A - Electrostatic type ink jet recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make ink density and the like constant by stably circulating ink and consequently realize stable printing quality by a method wherein a circulating part for circulating the ink with pumps is provided by communicating an ink chamber and an ink storing part with the predetermined number of influx pipe lines and pressure controlling pipe lines. SOLUTION: Seeing from an ink chamber 2, an ink storing part 3 and a head part 1 are communicated with each other through at least one or more of influx pipe lines 4, efflux pipe lines 5 and pressure controlling pipe lines 6. Pumps 7 and 9 are provided in the respective midways of the influx pipe line 4 and of the efflux pipe line 5 so as to forcibly circulate ink 8 to an influx direction 18 and to an efflux direction 19. The pressure controlling pipe line 6 is kept under the state that its interior is filled with the ink 8. In addition, in the midway of the pipe line 6, a detecting means 13 for detecting the flowing direction of the ink is equipped. Thus, the ink 8, which is fresh at all times, can be circulated through a discharging part 10. In addition, when the pressure at the discharging part 10 becomes abnormal, the abnormal pressure can quickly be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic ink jet recording apparatus, and more particularly, to an electrostatic ink jet recording apparatus which uses an ink in which toner particles are dispersed in a carrier liquid and performs recording by flying toner particles by electrostatic force. Related to the device.

[0002]

2. Description of the Related Art Conventional ink supply methods in an ink jet recording apparatus using a liquid ink as a recording material are roughly classified into two types. One is a method of replenishing the ink consumed by ejection from an ink storage unit by a meniscus force generated in its own ejection unit without using a pump for ink supply. This is mainly a drop-on-demand type ink jet recording. Used in equipment. The other is a method in which ink is supplied from an ink storage unit to a head unit by a pump, and is mainly used in a continuous type ink jet recording apparatus.

However, in the former case, the ink flows only in one direction from the ink storage section to the ink chamber, and the ink does not circulate. The latter is disclosed in, for example, JP-A-5-185600 and JP-A-5-2619.
No. 36, and the like. Although these are circulating ink, the direction of flow caused by the pump is only one direction from the ink storage unit to the ink chamber, and the ink in the ink chamber is pushed out by the fed ink and enters the ink storage unit. By returning, the ink circulation was performed. Furthermore, no pressure regulating line is provided. In addition, Japanese Unexamined Patent Publication
In Japanese Patent Publication No. 520, the ink storage section and the ink chamber are connected by two ink flow paths, but also in this case, no pressure adjustment conduit is provided.

[0004]

The ink used in the electrostatic ink jet recording apparatus of the present invention is one in which charged toner particles are distributed in an insulating solvent. Although a small amount of solvent is involved in ejection, most of the flying components are toner. In other words, as the ejection continues, the toner in the ink is consumed, so the density of the toner in the ink gradually decreases as the ejection proceeds, the amount of toner gathering at the ejection electrode unit decreases, and the ejection amount decreases, that is, the print dot A phenomenon occurs in which the diameter is reduced, the print density is reduced, and if the ejection is further continued, the ejection eventually stops.

[0005] Therefore, the ink in the vicinity of the discharge section of the recording apparatus must always be circulated between the ink and the new ink in the ink storage section, and the ink is caused by its own meniscus force as in the conventional drop-on-demand system. In the ink supply, it is impossible to supply the toner in the consumed ink.

[0006] In addition, as for the above-described ink supply such as a continuous system in which ink is circulated by using a pump, the conventional method only sends ink from the ink storage section to the ink chamber in one direction. is there. In order to force-circulate the ink by the drop-on-demand method, the ink sent into the ink chamber by the forced circulation must return to the ink storage unit without leaking from the ejection unit to the outside. Although an ink meniscus is usually formed in the ejection part and can absorb some pressure fluctuations, it is difficult to generate a meniscus force higher than the pipe resistance of the outflow pipe, especially when the flow velocity is high, and the Ink leakage is likely to occur.

In other words, both the ink replenishment by the meniscus force as in the conventional drop-on-demand system and the ink circulation by pushing out the ink from the ink storage unit used in the continuous system by the pump are used. It is not suitable as.

[0008] An object of the present invention is to provide a drop-on-demand method of electrostatic recording in which toner in a solvent is discharged,
An object of the present invention is to provide an electrostatic ink jet recording apparatus in which stable ink circulation is performed between an ink storage unit and an ink chamber, so that ink density or toner density in ink is constant and printing quality is stable. .

[0009]

According to the present invention, there is provided an electrostatic ink jet recording apparatus in which an ink chamber filled with an insulating ink containing charged toner and the ink chamber communicate with the outside. A discharge unit, a discharge electrode positioned near the discharge unit and configured to discharge the toner to the outside by applying a pulse voltage, and the toner positioned on the opposite side of the discharge unit in the ink chamber from the toner by electrophoresis. An electrophoresis electrode that concentrates on a discharge unit, an ink storage unit that stores the ink, and the ink chamber and the ink storage unit that communicate with at least one or more of an inflow pipe, an outflow pipe, and a pressure adjustment pipe. A circulating unit for circulating the ink by a pump.

Further, in the electrostatic ink jet recording apparatus according to the present invention, the pressure adjusting pipe of the circulating portion is provided with an ink formed in the discharge portion when a sudden change in the amount of ink occurs in the ink chamber. By the meniscus force of the meniscus,
It is characterized in that the fluid resistance and the inertia of the pressure regulating line are sufficiently small such that a flow occurs in the pressure regulating line.

Further, the electrostatic ink jet recording apparatus of the present invention is characterized in that both the inflow pipe and the outflow pipe of the circulating section pass through a pump.

Further, in the electrostatic ink jet recording apparatus according to the present invention, the circulating flow rate of the circulating section by the pump is:
The amount of ink flowing out to the ink chamber is equal to or slightly larger than the amount of ink flowing in.

Further, the electrostatic ink jet recording apparatus according to the present invention comprises:
It is provided with a determination unit that receives a signal from the detection unit and determines an abnormality when a flow in a direction opposite to that in a normal state occurs, and a display unit that displays a warning.

[0014]

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing an ink circulation system of an electrostatic ink jet recording apparatus according to an embodiment of the present invention. Referring to FIG. 1, the electrostatic ink jet recording apparatus according to this embodiment communicates with an ink chamber 2 whose inside is filled with an insulating ink containing charged toner, and the ink chamber 2 and the outside. The discharge unit 10 and the discharge unit 10
An ejection electrode 11 which is located in the vicinity and discharges the toner to the outside by applying a pulse voltage, and an electrophoresis electrode 12 which is located on the side opposite to the ejection portion 10 in the ink chamber 2 and concentrates the toner on the ejection portion 10 by an electrophoresis phenomenon. , An ink storage unit 3 for storing ink, and at least one or more inflow pipes 4 and outflow pipes 5 for each of the ink chamber 2 and the ink storage unit 3.
Circulating section for communicating ink with the pressure adjusting line 6 and circulating ink by the pumps 7 and 9; detecting means 13 for detecting a flow direction in the pressure adjusting line 6; and detecting means for detecting a flow in a direction opposite to the normal state. The display unit 20 includes a determination unit 14 that receives a signal from the controller 13 and determines an abnormality, and a display unit 20 that displays a warning.

The ink storage section 3 and the head section 1 are in communication with each other by at least one of each of an inflow pipe 4, an outflow pipe 5, and a pressure adjustment pipe 6, as viewed from the ink chamber 2. The inflow pipe 4 and the outflow pipe 5 pass through the pumps 7 and 9 on the way, respectively, and forcibly circulate the ink 8 in the inflow direction 18 and the outflow direction 19, respectively. The pressure adjustment conduit 6 is held in a state where the inside is filled with the ink 8,
On the way, a detecting means 13 for detecting the direction of ink flow is provided.

FIG. 2 is a perspective view of the head 1. Referring to FIG. 2, an electrostatic ink jet recording head according to the present embodiment has an ink chamber 2 whose inside is filled with an insulating ink 8 containing charged toner, and a discharge connecting the ink chamber 2 and the outside. A discharge unit 11 which is located near the discharge unit 10 and applies a pulse voltage to discharge the toner to the outside; And an electrophoresis electrode 12 which is concentrated on the electrophoresis electrode 10.

FIG. 3 is a sectional view when the ink chamber in the head portion of the electrostatic ink jet recording apparatus of this embodiment is under a negative pressure. The operation of the circulating system of the electrostatic ink jet recording apparatus according to this embodiment will be described with reference to FIG.

The ink 8 is fed into the ink chamber 2 from the inflow pipe 4 by the pump 7. The ink 8 flowing from the inflow pipe 4 by the pump 7 passes through the tip of the discharge electrode 11 and flows out of the outflow pipe 5. The pressure adjusting pipe 6 is held in a state where the inside thereof is filled with the ink 8, particularly without any forced flow. At this time, the ink outflow amount is made equal to or slightly larger than the ink inflow amount by the pump 7 or the pump 9. By doing so, the ink 8 in the ink chamber 2 tends to decrease with time, the ink meniscus 17 of the ejection unit 10 is held in a concave state, and the inside of the ink chamber 2 is in a negative pressure state. When the ink 8 is to be further reduced, the ink meniscus 17 is further concaved, the negative pressure in the ink chamber 2 due to the meniscus force is further increased, and an ink supply flow 15 is generated in the pressure adjusting pipe 6 to cause the ink 8 to flow. Is supplied. Also, when the volume in the ink chamber 2 is reduced due to the consumption of toner by ejection,
Since the negative pressure in the inside becomes large, the ink supply flow 15 is generated in the pressure adjustment pipeline 6. At this time, it is desirable that the inertial force and the fluid resistance force of the ink 8 flowing in the pressure adjusting pipe 6 be small, and it is necessary that the ink 8 be small at least to the extent that the flow is caused by the meniscus force generated in the ejection unit 10. Normally, the above state continues, so that the inside of the ink chamber 2 is always kept in a slightly negative pressure state and is kept stable.

FIG. 4 is a sectional view when the pressure in the ink chamber in the head section of the electrostatic ink jet recording apparatus of this embodiment is increased. Referring to FIG. 4 along with FIG.
When the ink 8 in the ink chamber 2 increases for some reason, first, the ink meniscus 17 of the ejection unit 10 becomes convex, and the pressure in the ink chamber 2 becomes positive. As a result, an ink discharge flow 16 in the opposite direction to the conventional one is generated in the pressure adjusting pipe 6, and the ink 8 in the ink chamber 2, which continues to increase, is all flown to the ink storage unit 3 by the ink discharge flow 16.
Further, at this time, since the pressure state in the ink chamber 2 is not normal, the detecting means 13 which has detected the flow in the pressure adjusting pipe 6 at this time outputs a warning on the display unit 14 or a warning sound via the judging unit 14. Notify the user of the abnormality.

As described above, according to the present invention, in the electrostatic ink jet recording apparatus for discharging the toner in the ink 8, the new ink 8 can be constantly circulated to the discharge section 10 stably, and Discharge part 1 depending on the cause
When the pressure state of 0 becomes abnormal, it can be detected promptly.

[0022]

As described above, the first effect of the electrostatic ink jet recording apparatus of the present invention is that a stable recording operation can be realized. The reason for this is that the pressure state in the ink chamber is always kept constant by the pressure adjustment conduit, and the pressure change in the ink chamber is minimized even if an unexpected pressure fluctuation occurs due to disturbance or the like.

The second effect is that an abnormality in the ink circulation system can be detected. The reason is that an abnormal flow can be detected by having a detecting means for detecting the flow occurring in the pressure adjusting pipeline.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an ink circulation system of an electrostatic ink jet recording apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view of a head unit according to the embodiment.

FIG. 3 is a cross-sectional view when a negative pressure is applied to an ink chamber in a head portion of the electrostatic ink jet recording apparatus according to the embodiment.

FIG. 4 is a cross-sectional view when the pressure in an ink chamber in the head unit of the electrostatic ink jet recording apparatus according to the embodiment increases.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Head part 2 Ink chamber 3 Ink storage part 4 Inflow line 5 Outflow line 6 Pressure adjustment line 7 Pump 8 Ink 9 Pump 10 Discharge part 11 Discharge electrode 12 Electrophoresis electrode 13 Detecting means 14 Judgment part 15 Ink supply flow 16 Ink Discharge flow 17 Ink meniscus 18 Inflow direction 19 Outflow direction 20 Display

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Junichi Suetsugu 7546 Yasuda, Kashiwazaki-shi, Niigata Prefecture Niigata Nippon Electric Co., Ltd. (72) Inventor Hitoshi Minemoto 7546 Yasuda, Kashiwazaki-shi, Niigata Niigata Nippon Electric Co., Ltd. (72) Inventor Hitoshi Takemoto 7546 Yasuda, Kashiwazaki-shi, Niigata Prefecture Niigata Nippon Electric Co., Ltd. (72) Inventor Kazuo Shima 7546 Yasuda, Oji, Kashiwazaki-shi, Niigata Niigata Nippon Electric Co., Ltd. 7546 Yasuda, Kashiwazaki, Niigata Prefecture Niigata Nippon Electric Co., Ltd.

Claims (5)

[Claims] 1. An ink chamber filled with insulating ink containing charged toner, an ejection unit communicating the ink chamber with the outside, and a pulse voltage applied near the ejection unit. A discharge electrode for discharging the toner to the outside, an electrophoresis electrode located on a side of the ink chamber opposite to the discharge portion and for concentrating the toner on the discharge portion by electrophoresis, and an ink for storing the ink. A storage unit, and a circulation unit configured to communicate the ink chamber and the ink storage unit with at least one or more of an inflow pipe, an outflow pipe, and a pressure adjustment pipe, and to circulate the ink by a pump. Electrostatic ink jet recording apparatus. 2. The pressure-adjusting conduit of the circulating unit, wherein when a sudden change in the amount of ink occurs in the ink chamber, the pressure-adjusting conduit is formed by a meniscus force of an ink meniscus formed in the ejection unit. 2. The electrostatic ink jet recording apparatus according to claim 1, wherein the fluid resistance force and the inertia force of the pressure adjusting conduit are sufficiently small to cause the flow to occur. 3. The pump according to claim 1, wherein both the inflow line and the outflow line of the circulation section pass through a pump.
Or the electrostatic ink jet recording apparatus according to 2. 4. The electrostatic ink jet according to claim 3, wherein a circulation flow rate of the circulation section by the pump is such that an amount of ink flowing out to the ink chamber is equal to or slightly larger than an amount of ink flowing in. Recording device. 5. A detecting means for detecting the direction of flow in the pressure regulating pipeline, a determining unit for receiving a signal from the detecting means when a flow in a direction opposite to a normal state occurs and determining an abnormality, and displaying a warning. 2. The electrostatic ink jet recording apparatus according to claim 1, further comprising a display unit.