JP2595972B2 - Ink jet recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to an ink jet recording apparatus for recording characters and the like on a recording medium by ejecting ink droplets from nozzles, and in particular, for stably recording characters and the like. Cleaning of print head,
It is about protection.

[Conventional technology]

In this type of conventional ink jet recording apparatus, it has been impossible to stably record characters and the like for a long time.

[Problems to be solved by the invention]

In this type of ink jet recording apparatus, ink droplets are ejected from nozzles due to a sudden change in pressure in an ink chamber inside the print head due to vibration of an electric distortion oscillator, etc. Paper dust generated from paper when the medium is paper, dust in the operating environment,
If dust or the like adheres, there is a problem that normal ejection of ink droplets cannot be performed.

Therefore, the present invention is to solve such a problem, and an object of the present invention is to provide a highly reliable ink jet recording apparatus which has a very simple structure, always keeps a nozzle portion of a print head in a stable state, and has no character missing or the like. It is in.

[Means for solving the problem]

The ink jet recording apparatus of the present invention comprises: a cap means which covers the print head surface after the printing operation is completed, and which operates to separate from the print head surface immediately before the start of printing; and A suction unit that operates to make the inside of the cap unit a negative pressure; and, during the suction operation by the suction unit, communicates the inside of the cap unit with the atmosphere and adjusts the inflow amount of the air to control the minute amount from the print head. Control means for controlling the suction force of the suction means so as to cause the ink to flow out.

[Action]

According to the present invention, the ink suction force of the ink suction means is reduced as much as possible by the control means, and the operation of sucking a small amount of ink from the print head is performed at the time of non-printing after the printing operation, so that the nozzle portion of the print head is The nozzle portion is maintained in a state in which it is possible to always eject a stable and stable ink droplet without adhesion of the washed and dried ink, paper dust generated from the recording medium, dust and the like in the operating environment. In addition, in the case where foreign matter such as dust and dust adheres to the nozzle portion, recording defects such as missing characters rarely occur immediately after the adherence. The ink adhesion state at the front of the nozzle portion gradually changes, and the normal state is lost, which eventually results in a recording failure such as missing characters.It is not necessary to perform the above operation immediately after foreign matter such as dust and dust adheres. Even if the ink suction operation is performed during non-printing before the next printing operation after the continuous printing operation, there is no practical problem.

〔Example〕

FIG. 1 shows an embodiment of an ink jet recording apparatus, wherein reference numeral 1 denotes a print head which is guided by a guide member 7 and moves in the axial direction of a platen 8; Ink cartridge 9
From the ink supply tube 10 and the filter device 11.

Reference numeral 2 denotes a cap for protecting the print head 1, which is disposed at the home position of the print head 1 and hermetically contacts the front surface of the print head 1. The suction operation of the ink is performed by forcibly flowing the ink from the nozzle portion of the print head 1 through the cap 2 by the suction pump 3, and the overflowed ink is stored in the ink cartridge 9 or a separately provided waste ink reservoir.

FIG. 2 is a detailed view of the print head 1 used in one embodiment of the present invention. Ink flowing into the print head 1 via the ink supply tube 10 passes through the ink chamber 12 and the nozzle 13
More outflow.

Next, FIGS. 3 and 4 show a configuration which is a characteristic part of the present invention, such as a control means for controlling the ink suction force. Third
The drawing shows a cap 2 attached to a print head 1 in an embodiment of the present invention.
FIG. 3 is a detailed view of a state in which ink can be sucked by abutting;
Is a print head having a nozzle 13 for ejecting ink, and 2 is a print head 1 at the time of ink suction and non-printing operation.
A suction pump 3 is connected to the cap 2 via a pipe 4. Reference numeral 5 denotes a valve connected to the cap 2 by a thin tube 6 for communicating or blocking the inside of the cap 2 with the atmosphere. When the suction pump 3 operates and the inside of the cap 2 becomes negative pressure, ink flows out of the nozzle 13 of the print head 1. The thin tube 6 is moved from the atmosphere into the cap 2 by the operation of the valve 5. A thin tube of a certain size is used so that the ink does not flow rapidly or in large quantities when the ink flows out, and the valve 5 and the thin tube 6 constitute a control means for controlling the ink suction force. FIG. 4 shows an embodiment of the valve 5 used in the present invention, in which reference numeral 14 denotes a DC solenoid, 15 denotes a plunger which moves upward by energization, and 16 denotes a rubber member which is attached to the tip of the plunger 15 and Works with jar 15. That is, the rubber member 16 normally closes the outlet of the thin tube 6 by the spring 17, and the outlet of the thin tube 6 is opened by moving the rubber member 16 upward against the spring 17 by energizing.

Next, the ink suction operation will be described. In the case where the print head 1 is filled with ink and during the purging operation such as discharging bubbles in the flow path, the cap 2 is brought into airtight contact with the print head 1 as shown in FIG. The valve 5 is closed with the suction pump 3
Is operated to suck ink from the print head 1. still,
During this operation, a large amount of ink can be sucked. Next, a description will be given of a suction operation of a small amount of ink which is a feature of the present invention. When the valve 5 is opened and the suction pump 3 is operated in a state where the cap 2 is in airtight contact with the print head 1, the cap is operated by the operation of the suction pump 3. The inside of the cap 2 becomes a negative pressure, and air flows into the cap 2 from the atmosphere through the valve 5. At this time, the air flowing through the thin tube 6 is suppressed by the resistance determined by the diameter and length of the thin tube 6, and the negative pressure in the cap 2 is not completely released, so that a small amount of ink flows out of the print head 1. I do. The front surface of the nozzle 13 of the print head 1 is washed by a small amount of the ink to remove dry ink, dust, dust and the like. The amount of ink flowing out in a minute amount is set to a value within the range of 0.
In the present embodiment, a plastic tube having an inner diameter of 0.3 to 0.55 mm and a length of 80 to 150 mm is used, and the operation time of the suction pump 3 is set to about 0.3 to 0.6 seconds. .

Next, FIG. 5 shows a flowchart in the embodiment of the present invention. Although not shown, the cap 2 is used in this embodiment.
The opening and closing operation of the print head 1 is linked with the drive shaft of the suction pump 3, and the cap 2 closes when the drive shaft rotates forward.
The cap 2 is configured to perform an opening operation at the time of reverse rotation,
The opening and closing operations of the cap 2 can be performed in about 0.2 seconds.

Next, the operation will be described according to a flowchart.
After the printing operation is completed and a non-printing state is reached, the print head 1
Moves to a position facing the cap 2 and stops. next,
The valve 5 is opened, and the suction pump 3 is operated for 0.5 seconds to bring the cap 2 into contact with the print head 1. At this time, the ink suction operation is performed with the valve 5 opened, and a small amount of ink flows out of the print head 1. Next, the valve 5 is closed, and the cap 2 is kept in the closed state until the next printing operation to protect the print head 1 from foreign matter. To perform the printing operation again, the valve 5 is opened, the suction pump 3 is operated, and the cap 2 is opened.
And the print head 1 moves to the printing position to perform a printing operation. Thereafter, the above operation is repeated.

As described above, according to the present invention, by providing the suction pump with the suction force control means, frequent cleaning using a small amount of suction is made possible. In addition, the above-mentioned small amount suction operation is not limited to the case where it is always performed at the time of CAP during non-printing, and it is confirmed that the effect is sufficient only when the printing operation signal is not entered for a certain time, or when the printing time is long, etc. is made of.

〔The invention's effect〕

As described above, according to the present invention, at the time of non-printing between printing operations, the printing head surface is covered with the cap means and the control means adjusts the inflow amount of air into the cap by the printing head. By suctioning a small amount of ink from the nozzle, the dry ink attached to the nozzle of the print head, paper dust generated from the recording paper, dust and dirt in the operating environment, etc. are washed and the state of the nozzle is reduced. This enables normal printing and good printing with no missing characters. Further, since a minute amount of ink can be sucked by the control means, it is possible to eliminate or prevent a defective ink ejection of the nozzles while suppressing the ink consumption. Therefore, even if the printing operation is interrupted and this suction is performed frequently, it does not significantly affect the ink consumption.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of an ink jet recording apparatus of the present invention. FIG. 2 is a detailed view of a print head. FIG. 3 is a detailed view of a cap portion. FIG. 4 is a detailed view of a valve. FIG. 5 is a flowchart. DESCRIPTION OF SYMBOLS 1 ... Print head 2 ... Cap 3 ... Suction pump 5 ... Valve 6 ... Thin tube 9 ... Ink cartridge 13 ... Nozzle

Claims (1)

(57) [Claims] 1. A printing head surface is coated after a printing operation is completed.
A cap means that operates to separate from the print head surface immediately before the start of printing; a suction means that operates to reduce the pressure inside the cap means to a negative pressure after the cap means covers the print head surface; Control means for controlling the suction force of the suction means so as to allow the inside of the cap means to communicate with the atmosphere and adjust the inflow amount of air to cause a minute amount of ink to flow out of the print head during the suction operation by the means. An ink jet recording apparatus comprising: