JPH04185451A - Ink jet recording device - Google Patents

Abstract

PURPOSE:To make recovery of ink discharge function possible in malfunction of ink drop discharging, and to prevent occurrence of the malfunction in ink drop discharging by a method wherein the ink is sucked with a cap stuck to an ink drop discharging part when the pressure is applied to the ink. CONSTITUTION:With an instruction for execution of removal of air bubbles and alien substances given, a head carriage 1 moves to an ink supply position. As confirmation is made by detection that the movement is made to a specified position, a cap 223 and connecting parts 224 and 225 are pushed successively toward the head carriage 1 side, and thereby an ink drop discharge part is closed tight. With an ink supply passage connected, valving mechanism 226, 227 operate, making the valve 226 closed, and the valve 227 closed on the atmosphere side, and thereby an ink supply pump 221 and an ink discharge pump 222 operate. With the difference between the positive pressure applied by the ink supply pump 221 and the negative pressure applied by the ink discharge pump 222 given to the ink, sufficient dynamic pressure can be obtained in the flow of the ink, and thereby removal of the air bubbles and the alien substances becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the ink supply system of an inkjet recording apparatus, and more specifically, to recovery from a time when the print head of an inkjet recording apparatus is unable to eject ink droplets.

and prevention of inability to eject ink droplets.

An inkjet recording device prints characters on a recording medium by ejecting small droplets of ink from tiny openings.

It records figures etc. in dots. In order to eject this ink with high precision, it is necessary to prevent air bubbles from entering the ink flow path within the recording head.

Furthermore, due to drying of the ink in the nozzle, paper dust, etc., solidified substances may be formed in the ink, which may clog the nozzle, and it is necessary to remove these impurities or prevent their generation.

Conventionally, the following measures have been taken when air bubbles or foreign matter enter the nozzles or other ink flow paths in the recording head.

(1) A method of pressing the movable or flexible part of the ink cartridge to increase the ink pressure and eject air bubbles, foreign matter, etc. from the nozzle at the end of the ink flow path together with the ink.

(2) A pressurized chamber is provided in the middle of the ink supply system that fluidly connects the ink tank and the recording head, and the ink is sent to the nozzle side by increasing the ink feed amount and ink pressure using an electric pump, etc., and air bubbles and foreign substances are removed from the nozzle. (Japanese Unexamined Patent Publication No. 55-53570).

(3) A method in which a cap is placed close to the nozzle surface and a suction pump is used to suck out ink from the nozzle to remove air bubbles and foreign matter (Japanese Patent Application Laid-Open No. 113464/1983), a pressurizing air pump and a suction air pump. integrated and equipped with
Method for removing air bubbles and solid matter in the ink flow path (Japanese Patent Laid-Open No. 5
9-59455).

However, each of the above methods for removing air bubbles and foreign matter has the following drawbacks.

(1) The mechanical pressure method described in (1) above lacks pressure accuracy and stability, and in particular, it is difficult to apply constant pressure regardless of the amount of ink remaining, and it is difficult to apply pressure to the ink storage bag. There is a risk that force will be applied and the ink storage bag will be damaged.

(2) The method using a pump, etc. in (2) above increases the ink pressure enough to remove air bubbles and foreign matter, which may cause ink leakage or damage from various parts. There is a risk.

Furthermore, when the ink is pressurized, the air bubbles to be discharged also contract in volume, making them less susceptible to dynamic pressure from the ink flow.

(3) In the method (3) using negative pressure suction, the differential pressure during suction cannot be greater than 1 kgf/cj (atmospheric pressure). Therefore, especially when sufficient dynamic pressure is required due to the ink flow to remove foreign matter, the absolute value of the differential pressure cannot be obtained and it is difficult to discharge the foreign matter.

Jl-The present invention was made in view of the above-mentioned circumstances.
In particular, in the ink supply system of an inkjet recording device, recovery of ink ejection function when ink droplets cannot be ejected;
This is also intended to prevent the inability to eject ink droplets.

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention includes an ink pressurizing means for supplying pressurized ink to a print head section, and an ink droplet pressurizing means that is removably attached to an ink drop ejection section of the print head section. a cap that seals the ejection section; and an ink suction means that communicates with the cap and sucks ink from the head section, and when the ink pressurizing means is executed, the cap is brought into close contact with the ink droplet ejection section; The present invention is characterized in that the ink suction means is executed, and further characterized in that the operation of the ink suction means is stopped with a time delay after the operation of the ink pressurizing means is stopped. Hereinafter, the present invention will be explained based on examples.

FIG. 4 is a main part configuration diagram for explaining an example of an inkjet recording apparatus to which the present invention is applied. In the figure, 1 is a helad carriage, 2 is an ink supply unit (main ink tank), and 3 is a recording 101 is a carriage drive motor, 102 is a carriage drive belt, 103 is a motor pulley, 111 is a carriage guide, and 301 is a paper guide.

Reference numeral 302 denotes a paper feed roller, which, as is well known, drives the head carriage 1 reciprocatingly in the direction of arrow A using the carriage drive motor 101, and conveys the recording paper 3 in the direction of arrow B. Ink droplets are ejected from nozzles mounted on a head carriage 1 to print on recording paper 3.

In the above-described inkjet recording apparatus, in order to eject ink with high precision, it is necessary to prevent air bubbles from entering the ink flow path in the recording head, as described above. Further, drying of the ink in the nozzle, paper dust, etc. may cause solidified substances in the ink, which may cause clogging of the nozzle, and it is necessary to remove these impurities or prevent their generation.

The present invention has been made to solve the above-mentioned problems, and will be described below with reference to the drawings.

FIG. 1 is a main part configuration diagram for explaining an embodiment of the present invention, and this figure shows a state in which the head carriage 1 has moved to the position of the ink supply unit 2. As shown in FIG. In this configuration, the head carriage 1 is reciprocated in the six directions of arrows by the drive of the carriage drive motor 101, and the print head section 120 disposed on the head carriage 1 is directed toward the recording paper in response to the recording image signal. to eject ink droplets and perform recording. Ink corresponding to the ink droplets ejected at this time is quickly supplied from the sub-ink tank 130. When the amount of ink in the sub-ink tank 130 falls below a specified amount (set by the remaining ink level sensor, print or paper feed counter, etc.), the main ink tank 21 of the ink cartridge 210 is removed by the operation of the ink supply unit 2.
1, ink is supplied to the sub-ink tank 130 of the head carriage 1. This ink supply is executed by moving the head carriage 1 to an ink supply position where the ink supply unit 2 is arranged.

The ink supply unit 2 includes an ink cartridge 210 holding a main ink tank 211 and a waste liquid reservoir 212;
It is composed of an ink supply pump 221, an ink discharge pump 222, a head cap 223, an ink supply connection part 224, an atmosphere release connection part 225, a valve mechanism 226, a switching valve 227, and the like.

The main ink tank 211 is an ink cartridge 210
A case with a structure having an atmosphere communication hole 214 in a part thereof, a porous body provided in the main ink tank 211, or an ink bag is used and the ink is stored in the ink bag. may be held.

The waste liquid reservoir 212 uses, for example, an ink absorber, and the ink supply pump 221 and the ink discharge pump 222 can use a tubing pump, a piston pump, a diaphragm pump, or the like.

The head cap 223, the ink supply connection part 224, and the atmosphere release connection part 225 are each made of soft rubber such as silicone rubber, and are pressed against the print head 12o and the sub-ink tank 130 by a spring member (not shown) or the like. If necessary, they can be separated using a solenoid or the like.

Note that when the power is OFF, the head carriage 1 is in the ink supply position, and the head camp 223 and the connection part 224 are in the ink supply position.
,． 225 and the like are pressed against the head carriage 1.

On the other hand, the head carriage 1 includes a carriage base 110, a print head section 120, and a sub-ink tank 130.

The carriage base 110 slides on the carriage guide 111, and the head carriage 1 is reciprocated by being driven by the carriage drive motor 101.

The print head section 120 has nozzles and usually has a multi-configuration in which a plurality of print drive units are arranged.

The sub-ink tank 130 is inside the ink reservoir.

For example, a structure having an ink holding portion 131 made of a porous material, or a structure having a film body 131 as shown in FIG.
5 (the film body 135 is deformed to change the volume of the ink reservoir), and the film body 135 holds ink □.

These sub-ink tank holding parts 131 and 135 are moved by moving and scanning the head carriage 1.
It is possible to prevent pressure fluctuations in the ink section (supplied ink) that occur within the range of 0.

This sub-ink tank 130 is further provided with a filter 134 at an outlet portion that supplies ink to the print head portion 120 side. Also.

The ink supply port 132 and the atmosphere release port 133 are connected to the connection part 224
．． It has a tapered shape corresponding to 225.

Note that a check valve function may be provided in the ink supply port 132 (not shown).

Next, ink supply in one or more configurations will be described.

When a sensor (not shown) detects that the head carriage 1 has moved to the ink supply position, the cap 22
3. The operation of the solenoids that move the connecting parts 224 and 225 is turned off, and the nozzles 121. Connection port 132,1
33, and the ink supply system is connected (this suppressing operation may open a valve function installed at the connection port 132).

When the ink supply line is connected, the ink supply pump 22
1 operates to supply a certain amount of ink in the main ink tank 211 or until a sensor provided in the sub ink tank 130 detects that it is full. At this time, the valve mechanism 227 is connected to the main ink tank 211.
It opens between the ink supply pump 221 and the ink supply pump 221, and closes on the atmosphere side.
Valve mechanism 226 is open. The supplied ink is held in the ink holding section 131 or 135.

Also, at this time, some of the ink overflows through the atmosphere opening port 133 and the atmosphere opening connection part 225, and the waste liquid reservoir 2
12 may be discarded. When the ink supply ends, the operation of the ink supply pump 221 stops.

FIG. 2 is a block diagram for explaining another embodiment of the present invention, in which the supply connection is connected to the tubes 136, 1.
37 for constant connection, and the functions and operations are the same as those of the embodiment shown in FIG. According to this embodiment, the head carriage 1 does not need to move to the ink supply position, and ink can be supplied immediately.

Next, removal of air bubbles, foreign matter, etc. in the ink supply system will be explained.

Now, when the execution command for removing air bubbles and foreign matter is given, the head carriage 1 moves to the ink supply position, as in the case of ink supply, and when the sensor detects that the head carriage 1 has moved to the predetermined position, the cap 223 , connection parts 224, 225
are sequentially pushed toward the head carriage 1 side (however, in the embodiment shown in FIG. 2, only the cap 223), the ink supply and discharge system is completed, and the cap
The pressure 3 seals the ink droplet spout portion of the print head. When the ink supply system is connected in this way, the valve mechanisms 226 and 227 are activated, and the valve 226 is closed.
The valve 227 is closed on the atmosphere side, and the ink supply pump 2
21, the ink discharge (suction) pump 222 is activated. However, at this time, desirably, the operation of the ink supply pump 221 is started after the ink discharge pump 222 starts operation, so that the ink discharged from the ink droplet ejection opening (nozzle) 121 is discharged from the cap 223. The waste liquid is absorbed into the waste liquid reservoir 212 without leaking.

When the pumps 221 and 222 operate, a pressure difference between the positive pressure from the ink supply pump 221 and the negative pressure from the ink discharge pump 222 is applied to the ink. Compared to the case where the required pressure difference is obtained by the ink flow, the strength may be weaker than the case where the necessary pressure difference is obtained by the ink flow, and as a result, a sufficient dynamic pressure due to the ink flow can be obtained, making it possible to remove air bubbles and foreign matter.

a certain period of time set to be sufficient for air bubbles and foreign matter to be expelled;
Alternatively, when a certain amount of ink outflow is detected, a command is given to end the removal operation, the operation of the ink supply pump 221 is stopped, the valve 227 is switched, and the main ink tank 221 side is closed to the atmosphere side.

As a result, ink is discharged from the ink droplet ejection port 121 only by suction by the ink discharge pump 222.

After this suction operation is completed, the cap 223, the connection part 224
, 225 are separated from the Herad carriage 1 (however, in the embodiment shown in FIG. 2, only the cap 223).

Furthermore, after the drained ink in the cap 223 is suctioned and discharged by the ink discharge pump 222, the operation of the ink discharge pump 222 is stopped, and the series of operations for removing air bubbles and foreign matter is completed.

Note that the timing of this series of operation stops ensures that the ink discharged from the ink droplet ejection port 121 and accumulated in the head cap 223 is absorbed into the ink discharge pump 222, so that the area around the print head and the recording device are free from ink. This is very useful as it prevents staining.

Figure 3 shows the head cap 2 shown in Figures 1 and 2.
23, in which (a) is a perspective view;
Figures (b) and (c) are cross-sectional views showing different embodiments, in which 223-1 is a thin wall portion that fits closely to the nozzle part to ensure airtightness, and 223-2 is a hend cap exhaust hole. 223-3 is a drained ink storage portion, and 223-4 is an ink absorber.

(b) As shown in the figure, it is preferable that the cap 223 has a drained ink reservoir, or (C) as shown in the figure, that the cap 223 has an absorbent body 223-4. by this.

The ink discharged just before the removal operation ends can be temporarily held in the cap, as described above.

After separating the bed cap 223, the head cap 22
The discharged ink within the ink can be absorbed by the operation of the ink discharge pump 222.

effect As is clear from the above description, according to the present invention.

The ink pressurizing means and the ink absorbing means are operated simultaneously,
It is possible to obtain a sufficient differential pressure to remove air bubbles, foreign matter, etc., and improve clogging removal performance and air bubble discharge performance. Also.

Since both the positive pressure from the ink pressurizing means and the negative pressure from the ink suction means are used, ink will not leak even if the pressure resistance of the head is not significantly increased. Furthermore, since the discharged ink temporarily held in the head cap can be collected by suction, the area around the print head and the recording device will not be contaminated by ink discharged just before the bubble/foreign object removal operation is completed.

There are advantages such as

[Brief explanation of the drawing]

1 and 2 are main part configuration diagrams for explaining the present invention in detail, FIG. 3 is a diagram for explaining an example of a bed cap, and FIG. 4 is a diagram to explain the present invention in detail. 1 is a main part configuration diagram for explaining an example of an inkjet recording apparatus. DESCRIPTION OF SYMBOLS 1... Head carriage, 2... Main ink tank, 3... Recording paper, 110... Carriage base, 12
0... Print head unit, 130... Sub ink tank, 131... Ink holding unit, 210... Ink cartridge, 211... Main ink tank, 212... Waste liquid reservoir, 223... Head cap. Patent applicant Akichika Takano, Rico Co., Ltd.
(and 1 other person) Figure 1 + Figure 2 +35

Claims (1)

[Scope of Claims] 1. An ink pressurizing means for supplying pressurized ink to a print head, and a cap that is detachably attached to an ink droplet ejection portion of the print head and seals the ink droplet ejection portion; an ink suction means that communicates with the cap and sucks ink from the head section, and when the ink pressurizing means is executed, the cap is brought into close contact with the ink droplet ejection section and the ink suction means is executed. An inkjet recording device featuring: 2. The inkjet recording apparatus according to claim 1, wherein the operation of the ink suction means is stopped with a time delay after the operation of the ink pressure means is stopped.