JPH10129008A - Ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably discharge ink by providing an ink pressure feeding means for pressure feeding bidirectionally and a first mesh filter at a supply tube for connecting a tank to a recording head, providing a second mesh filter at a return tube, and inverting plural times an ink pressure feeding direction at a predetermined timing. SOLUTION: Ink supply to a recording head 1a at the time of a recording operation is conducted via a return tube 12a by own weight of ink from a tank 13a. A foreign matter carried from the tank 13a is captured by a second mesh filter 35a. At the time of normal recovery, discharge ports 31a of the head 1a are capped. The ink is pressurized and circulated in a direction A by an ink pressure feeding means 24a, and returned to the tank 13a from the tube 12a. The foreign matter carried from the tank 13a is captured by a first mesh filter 34a. When clogging occurs, a reverse voltage is applied to the means 24a, the ink is pressurized and circulated in a reverse direction B. Thus, ink mixed with released foreign matter is fed to a waste ink tank 21a, and the matter can be removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-jet recording apparatus, and more particularly to an ink-jet recording apparatus which performs recording by discharging ink with thermal energy.

[0002]

2. Description of the Related Art Conventionally, there are various ink jet recording systems in which recording is performed by discharging ink on a recording sheet, and a thermal ink jet system in which ink is discharged using thermal energy (for example, US Pat. No. 4,723,471).
No. 29, U.S. Pat. No. 4,740,796) provide multi-color inks which have good responsiveness to recording electrical signals, facilitate high-density multi-hole ejection orifices, and reduce noise during recording. Since it has advantages such as easy color image recording by use, its future prospects are more promising than other ink jet recording methods.

However, in this type of ink jet recording apparatus, during a normal recovery operation for removing bubbles remaining in a liquid chamber of a recording head or an ink supply system, the ink is stored in a tank in which ink is stored. When pressurizing and supplying ink to the recording head, when foreign matter such as fine dust and dust contained in the ink enters the recording head and reaches the nozzle, the nozzle is clogged by the foreign matter, and the ink is clogged. No discharge from the nozzle. Therefore, in order to prevent such non-ejection of ink,
A mesh filter is provided in the middle of an ink supply system connecting the supply tank and the print head by widening the opening of the nozzle, so that the foreign matter does not enter the print head.

[0004]

However, in the above conventional example, there is a disadvantage that the recording density becomes coarse when the opening of the nozzle is widened, and even if the mesh filter is provided, it is not possible to catch the recording during the normal recovery operation. The eyes of the mesh filter are clogged by the foreign matter, and the normal recovery operation cannot be performed sufficiently thereafter. Therefore, there is a disadvantage that the ink is not ejected from the ejection port of the previous recording head.

An object of the present invention is to provide an ink jet recording apparatus capable of stably ejecting ink from a recording head.

[0006]

According to the present invention, there is provided an ink jet recording apparatus which comprises a recording head for discharging ink as small droplets from a discharge port, a tank storing ink, and connecting the tank to the recording head. A supply pipe provided with an ink pumping means capable of bidirectionally pumping ink and a first mesh filter, and a return pipe different from the supply pipe connecting the tank and the recording head and having a second mesh filter; And a recovery operation of reversing the ink pressure feeding direction of the ink pressure feeding means a plurality of times at a predetermined timing.

A waste ink tank for storing waste ink, a valve provided between the recording head of the supply pipe and the ink pressure feeding means, and guiding a part of the waste ink to the waste ink tank; And opening a valve during the recovery operation to guide a part of the waste ink ejected from the recording head to the waste ink tank.

The recording head is of a full line type in which discharge ports are formed over the entire width of the recording area of the recording sheet. Further, the recording head ejects ink using thermal energy, and includes an electrothermal converter for generating the thermal energy.

In the ink jet recording apparatus of the present invention, the foreign matter caught by the first mesh filter is vibrated by repeatedly inverting the ink feeding direction of the ink feeding means a plurality of times at a predetermined timing. Since the ink can be easily peeled off from the first mesh filter, the ink can be discharged from the recording head in a stable manner again.

[0010]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a diagram showing an ink supply system of a recording head 1a in one embodiment of the ink jet recording apparatus of the present invention, FIG. 2 is a perspective view showing one embodiment of the ink jet recording apparatus of the present invention, and FIG. Recording head 1a shown in FIG.
FIG. 4 is a perspective view showing a part of the structure of FIG.

The ink jet recording apparatus according to the present embodiment is a multi-color printing ink jet recording apparatus which discharges ink as fine droplets from fine discharge ports as shown in FIG.
A recording head unit 1 on which one recording head 1a to 1d is mounted, a carriage 3 on which the recording head unit 1 is mounted and which moves along two guide rails 4, and a timing for moving the carriage 3 Belt 5
And a drive motor 6, a pair of sheet feed rollers 9 for feeding the recording sheet 7 from the bottom to the top in the drawing, a sheet feed motor 8 for driving the sheet feed roller 9, and holding the recording sheet 7 at a recording position. The non-ejection of the recording heads 1a to 1d provided at a position facing the recording head unit 1 guided to the home position H and a pair of holding rollers 10 cooperating with the sheet feed roller 9 is performed. And a capping unit 14 that is sometimes used.

As shown in FIG. 3, the recording head 1a mounted on the recording head unit 1 has a liquid chamber 30a for storing ink supplied from the outside and a plurality of nozzles 33a provided in rows. And Each nozzle 33
a is provided with an electrothermal converter 32a that generates thermal energy for forming ink droplets to be ejected from the ejection port 31a in accordance with image information. That is, by a driving unit (not shown) in the inkjet apparatus,
A drive signal corresponding to the image signal is transmitted to the electrothermal transducer 3
2a, heat energy is generated in the electrothermal transducer 32a to cause film boiling, and bubbles are formed in the nozzle 33a. And, by the growth of the bubble, the discharge port 31 is formed.
The ink droplet is ejected from a.

As shown in FIG. 1, the ink supply system to the recording head 1a mainly includes a tank 13a storing the ink supplied to the recording head 1a, and a normal recovery of the recording head 1a. A supply pipe 11a for supplying ink from the tank 13a to the recording head 1a during operation;
A return pipe 1 for returning ink from the recording head 1a to the tank 13a during a normal recovery operation of the recording head 1a.
2a, an ink pumping means 24a provided in the supply pipe 11a and capable of pumping ink in both directions, comprising a gear pump, a waste ink tank 21a storing waste ink, the recording head 1a and the ink pumping apparatus. From the supply pipe 11a between the means 24a and the waste ink tank 21
and a valve 22a provided to guide a part of the waste ink to a. Liquid chamber 30a of the recording head 1a
The first mesh filter 34a and the second mesh filter 34a are connected to the connection points of the supply pipe 11a and the return pipe 12a, respectively.
Is provided. The same applies to the other recording heads 1b to 1d.

Next, the operation of the ink jet recording apparatus of this embodiment will be described.

During the recording operation, the carriage 3 shown in FIG.
Is moved from left to right in the figure by the drive motor 6 and the timing belt 5, and the cyan, magenta, yellow, and black inks are respectively recorded from the four recording heads 1a to 1d of the recording head unit 1. The image is recorded on the recording sheet 7 by being discharged. The recording sheet 7 is fed from the bottom to the top by a sheet feed motor 8 and a sheet feed roller 9 each time printing of one line is completed.

Next, the recording operation, the normal recovery operation, and the non-ejection recovery operation of the ink supply system of the four recording heads 1a to 1d will be described by taking the recording head 1a shown in FIG. 1 as an example. (1) Recording Operation The ink is supplied to the recording head 1a from the tank 13a shown in FIG. 1 via the return pipe 12a by the weight of the ink. At this time, the foreign matter carried from the tank 13a together with the ink is caught by the second mesh filter 35a, so that the nozzle 33a does not become clogged by the foreign matter during the printing operation, so that the ink is stably ejected from the ejection port 31a. be able to. (2) Normal recovery operation During the normal recovery operation performed at the time of removing bubbles remaining in the liquid chamber 30a of the recording head 1a and the ink supply system and initial filling of the nozzle 33a with ink, the recording shown in FIG. The carriage 3 is guided to the home position H by the drive motor 6 and the timing belt 5 so that the head unit 1 faces the capping unit 14. When the recording head unit 1 faces the capping unit 14, each ejection port 31a of the recording head 1a is capped by the capping unit 14 as shown in FIG. Thereafter, the ink stored in the tank 13a is pressurized and circulated in the direction A in the drawing by the ink pressure feeding means 24a and sent into the liquid chamber 30a. The sent ink is returned from the liquid chamber 30a to the tank 13a via the return pipe 12a. At this time, the foreign matter caught by the second mesh filter 35a during the recording operation described above is also pushed away by the ink and returned to the tank 13a. On the other hand, the supply pipe 11
The foreign matter carried through the first mesh filter 34a is caught by the first mesh filter 34a, but the ink is pressurized and sent by the ink pressurizing means 24a, so that the foreign matter caught by the first mesh filter 34a Of the second mesh filter 35 during the recording operation.
The amount is larger than the amount of foreign matter caught by a. as a result,
When the normal recovery operation is repeated several times and the first mesh filter 34a is clogged by foreign matter, the normal recovery operation is not sufficiently performed thereafter. It will not be ejected. (3) Non-ejection recovery operation At the time of non-ejection recovery operation performed when ink is not discharged from the recording head 1a, each ejection port 3 of the recording head 1a is operated in the same manner as in the normal recovery operation described above.
1a is capped by capping means 14. Thereafter, by applying a reverse voltage to the gear pump as the ink pressure feeding means 24, the ink stored in the tank 13a is pressurized and circulated in the direction B in FIG. Is fed into the liquid chamber 30a via the return pipe 12a. The supplied ink is capped at the discharge port 31a, so that the supply pipe 11
extruded into a. At this time, the ink separates the foreign matter caught by the first mesh filter 34a during the normal recovery operation from the first mesh filter 34a, so that the ink containing the foreign matter (hereinafter referred to as waste ink) Therefore, by opening the valve 22a, a part of the waste ink can be poured into the waste ink tank 21a via the supply pipe 11a and the valve 22a. As a result, by performing the non-discharge recovery operation, the first mesh filter 34a can be used during the normal recovery operation.
Since the captured foreign matter can be removed, the normal recovery operation can be performed again. Here, when the ejection failure recovery operation is performed, the second mesh filter 35a
A small amount of foreign matter may be caught on the side of the return pipe 12a, but there is no problem because the foreign matter can flow into the tank 13a together with the ink during the normal recovery operation. The operations described in the above (1) to (3) are the same for the other three recording heads 1b to 1d.

Next, a second embodiment of the ink jet recording apparatus of the present invention will be described.

In the first embodiment, the ink is circulated in the direction B in FIG. 1 by the ink pumping means 24a at the time of the non-ejection recovery operation. However, the ink jet recording apparatus of the present embodiment employs the ink pumping means 24a. This reverses the direction in which the ink is pressurized and circulated at a predetermined timing. That is, at the time of the non-ejection recovery operation, first, the ink is pressurized and circulated in the direction A in FIG. 1 for one second, and the pressurized and circulated ink in the direction B in the diagram for the next two seconds is repeated a plurality of times. The foreign matter captured by the mesh filter 34a is vibrated in the left-right direction in FIG.
Of the mesh filter 34a.

Instead of the valve 22a in the first and second embodiments described above, ink sent in the direction A in FIG. 1 is passed as it is, and a part of the ink sent in the direction B is stored in the waste ink tank 21a. The recording head 1 of the supply pipe 11a guides a valve through which the other ink is passed as it is.
a and the ink pressure feeding means 24a.

As a method of detecting the non-ejection of the recording heads 1a to 1d, an operator may detect the non-ejection, or an image sensor composed of a charge transfer device (CCD) may be used to record the image recorded on the recording sheet 7. For example, the detection may be automatically performed by monitoring in such a manner. Further, the non-discharge recovery operation may be performed each time printing of one or several lines on the printing sheet 7 is completed. In this case, since the non-discharge recovery operation is frequently performed, the occurrence of non-discharge can be minimized.

The amount of ink sent to the liquid chamber 30a may be changed between the normal recovery operation and the non-ejection recovery operation.

Further, the capping means 14 is provided with a known cleaning means for cleaning the nozzles of the recording heads 1a to 1d and a means for sucking ink sent from the supply pipe 11a at the time of a normal recovery operation from each of the discharge ports 31a. It may be something.

The first mesh filter 34a only needs to be provided at an arbitrary position of the supply pipe 11a between the recording head 1a and the valve 22a.
a is a return pipe 1 between the recording head 1a and the tank 13a.
What is necessary is just to be provided in the arbitrary position of 2a.

The present invention particularly provides an excellent effect in an ink jet recording apparatus using a bubble jet type recording head proposed by Canon Inc. among the ink jet recording methods.

The typical structure and principle are described in, for example, US Pat. Nos. 4,723,129 and 474.
It is preferred to use the basic principles disclosed in EP 0796. This method can be applied to both the so-called on-demand type and the continuous type. In particular, in the case of the on-demand type, liquid (ink)
By applying at least one drive signal that gives a rapid temperature rise exceeding the nucleate boiling corresponding to the recorded information, to the electrothermal transducer disposed corresponding to the sheet or liquid path in which , Heat energy is generated in the electrothermal transducer, and the film is boiled on the heat-acting surface of the recording head.
As a result, bubbles in the liquid (ink) can be formed in one-to-one correspondence with the drive signal, which is effective. The growth of this bubble,
The liquid (ink) is ejected through the ejection opening by contraction to form at least one droplet. With this drive signal pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable. The driving signal in the form of a pulse is disclosed in U.S. Pat.
Suitable are those described in US Pat. No. 45,262. Further, if the conditions described in US Pat. No. 4,313,124 of the invention relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

As the configuration of the recording head, in addition to the combination of a discharge port, a liquid path, and an electrothermal converter (a linear liquid path or a right-angle liquid path) as disclosed in the above-mentioned respective specifications, A configuration using each of those described in U.S. Pat. No. 4,558,333 and U.S. Pat. No. 4,459,600, which disclose a configuration in which the action portion is arranged in a bending region, may be used. In addition, JP-A-59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, and an aperture for absorbing a pressure wave of thermal energy is provided. The present invention is also effective as a configuration based on JP-A-59-138461 which discloses a configuration corresponding to a discharge unit.

Further, as a full-line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the ink jet recording apparatus, a combination of a plurality of recording heads disclosed in the above specification is used. Therefore, the present invention can exhibit the above-mentioned effects more effectively, though it may be either a configuration satisfying the length or a configuration as a single recording head formed integrally.

In addition, the print head is replaceable with a print head of a chip type, which is electrically connected to the main body of the apparatus and can supply ink from the main body of the apparatus, or is integrated with the print head itself. The present invention is also effective when a cartridge-type recording head provided in a fixed manner is used.

Further, it is preferable to add recovery means for the printhead, preliminary auxiliary means, and the like provided as components of the ink jet printing apparatus of the present invention since the effects of the present invention can be further stabilized. Specifically, for the recording head, a capping unit, a cleaning unit, a pressurizing or suctioning unit, a preheating unit using an electrothermal transducer or another heating element or a combination thereof, and a recording unit Separately, a preliminary ejection mode for performing ejection is also effective for stable printing.

Further, the recording mode of the ink jet recording apparatus is not limited to a recording mode of only a mainstream color such as black, but may be an integral recording head or a combination of plural recording heads. The present invention is also extremely effective for an apparatus provided with at least one of full colors by color mixture.

In the embodiment of the present invention described above,
Although the ink is described as a liquid, it is an ink that solidifies at room temperature or lower and softens or becomes liquid at room temperature, or a temperature range of 30 which is generally used for ink-jet temperature adjustment. It may be softened or liquid in a temperature range of not less than 70 ° C. and not more than 70 ° C.
That is, the ink may be in a liquid state when the use recording signal is applied. In addition, positively prevent the temperature rise due to thermal energy by using the energy of the state change of the ink from the solid state to the liquid state, or
In order to prevent evaporation of the ink, ink that solidifies in a standing state is used, and in any case, the ink is liquefied by application of a heat energy according to the recording signal, and the ink is discharged as a liquid ink or reaches a recording medium. The use of inks that liquefy for the first time with thermal energy, such as those that already begin to solidify at that point, is also applicable to the present invention. In such a case, the ink is disclosed in JP-A-54-56.
No. 847 or Japanese Patent Application Laid-Open No. Sho 60-71260, in which the porous sheet is opposed to the electrothermal converter while being held as a liquid or solid substance in the concave portion or through hole of the porous sheet. It is good also as a state. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

[0033]

According to the present invention, as described above, the foreign matter is vibrated and peeled off from the first mesh filter by repeatedly inverting the ink feeding direction of the ink feeding means a plurality of times at a predetermined timing. This makes it easy to stably eject the ink from the recording head.

[Brief description of the drawings]

FIG. 1 is a diagram showing an ink supply system of a recording head 1a in one embodiment of an ink jet recording apparatus of the present invention.

FIG. 2 is a perspective view showing an embodiment of the ink jet recording apparatus of the present invention.

FIG. 3 is a perspective view showing a part of the structure of the recording head 1a shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Recording head unit 1a, 1b, 1c, 1d Recording head 3 Carriage 4 Guide rail 5 Timing belt 6 Drive motor 7 Recording sheet 8 Sheet feed motor 9 Sheet feed roller 10 Holding roller 11a Supply pipe 12a Return pipe 13a Tank 14 Capping means 21a Waste ink tank 22a Valve 30a Liquid chamber 31a Discharge port 32a Electrothermal converter 33a Nozzle 34a First mesh filter 35a Second mesh filter A and B directions H Home position

Claims (4)

[Claims] 1. A recording head for discharging ink from a discharge port as small droplets, a tank for storing ink, and an ink pressure feeder for connecting the tank and the printhead and for bidirectionally pumping ink. Means and first
And a return pipe that connects the tank and the recording head and that is different from the supply pipe that includes the second mesh filter. The ink supply direction of the ink supply unit is predetermined. An ink jet recording apparatus comprising a recovery operation of inverting a plurality of times at the timing of (1). 2. A waste ink tank for storing waste ink, a valve provided between the recording head of the supply pipe and the ink pressure feeding means, and guiding a part of the waste ink to the waste ink tank; The inkjet recording apparatus according to claim 1, further comprising: opening the valve during the recovery operation to guide a part of the waste ink ejected from the recording head to the waste ink tank. 3. The ink jet recording apparatus according to claim 1, wherein the recording head is a full line type in which discharge ports are formed over the entire width of a recording area of the recording sheet. 4. The recording head according to claim 1, wherein the recording head discharges ink using thermal energy, and includes an electrothermal converter for generating the thermal energy. The inkjet recording apparatus according to any one of the preceding claims.