JPH1191137A - Ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain each nozzle in a print head smoothly and surely without staining the surroundings with ink. SOLUTION: A print head 20 (20C-20B) is coupled with an ink tank 40 through an ink supply tube 31 and an ink return tube 33 so that ink can be fed from the ink tank 40 to the print head 20 (20C-20B) by driving a feed pump 32 coupled with the ink supply tube 31 and can be returned from print head 20 (20C-20B) back to the ink tank 40 by driving a return pump 34 coupled with the ink return tube 33. The quantity of ink being fed by the feed pump 32 is set higher than the quantity of ink being returned by the return pump 34 so that both pumps 32, 34 can be driven simultaneously and the ink discharged from each nozzle 27 in the print head 20 (20C-20B) is received by a washing board 70 and fed to a waste ink cassette 80.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printer capable of supplying ink to a print head from an ink tank connected to the print head via an ink supply pipe and an ink return pipe.

[0002]

2. Description of the Related Art In a so-called serial type ink jet printer shown in FIG. 3, a print head 20P and an ink cassette (not shown) are mounted on a carrier 101 which can reciprocate along a guide bar 100, and a medium (paper) P is mounted. The ink is jetted from each nozzle while moving the print head 20P in the row (X) direction (the horizontal direction in the figure) to form an image. Each color ink nozzle of the print head 20P is single in the X direction. Therefore, for example, A4
It takes 10 minutes (0.1 PPM) for color printing of one size.

On the other hand, there has been proposed an ink jet printer capable of increasing the printing speed of, for example, 20 PPM (for example, Japanese Patent Application No. 8-296959).

In FIG. 4, nozzle units (20C, 20Y, 20M, 20M) for the respective colors forming the print head 20 are shown.
The nozzles for each color ink of B) are arranged in the longitudinal direction [row direction (X)] of the drum 10 carrying the medium (paper P), for example, at a pitch equivalent to the resolution or a pitch 2 to 4 times the pitch equivalent to the resolution. The nozzles are stationary in the X direction or are reciprocally movable in the X direction by the nozzle pitch.

[0005] The drum 10 has a medium (P) carried on its outer peripheral surface, for example, for 120 r around the axis Z.
It can rotate in the R direction at pm. Thus, for example, one A4 size sheet can be printed in color in a few seconds.

Further, since the print head 20 is almost stationary and the ink cassette does not have to be formed integrally with the print head 20, a large number of sheets can be continuously printed using a separate ink tank capable of filling a large amount of ink. It can be printed.

[0007]

In the ink jet printer, maintenance is performed by discharging ink from each nozzle during non-printing in order to prevent nozzle clogging and to remove gas (bubbles) in any type of ink jet printer. is necessary. However, it may not be possible to smoothly discharge the amount of ink required for maintenance from each nozzle.

[0008] The ink discharged from each nozzle is:
Adhesion to the surrounding dirt or printed surface reduces the print clarity. However, for example, printing several sheets a day has not been regarded as a problem.

However, when printing a large number of, for example, thousands of sheets continuously for one day, the ink (waste ink) discharged for maintenance is directly discharged to a predetermined location in the printer body. It is hard to forgive. This is because cleaning is difficult and handling is difficult from the viewpoint of reducing the size and weight.

An object of the present invention is to provide an ink jet printer which can maintain each nozzle of a print head smoothly and reliably without soiling the surroundings with ink.

[0011]

According to the present invention, a print head having a plurality of nozzles and an ink tank are connected via an ink supply pipe and an ink return pipe, and a feed pump provided in the ink supply pipe is driven. The ink in the print head can be returned to the ink tank by driving the return pump interposed between the ink tank and the print head and the ink return pipe interposed in the ink return pipe. The two ink pumps are formed so that they can be driven simultaneously by increasing the amount of ink returned by the printer, and a waste ink receiving member that can receive the ink discharged from each nozzle of the print head and send it to the waste ink recovery unit is provided. Is an inkjet printer.

In this case, both pumps are driven simultaneously so that the amount of ink sent by the feed pump is greater than the amount of ink returned by the return pump. Then, the pressure loss in both pump pipes is absorbed, and the ink is smoothly and reliably ejected from each nozzle of the print head to perform maintenance (prevention of clogging and degassing).

At this time, the ink (waste ink) discharged from each nozzle of the print head is reliably received by the waste ink receiving member and sent to the waste ink collecting section. Therefore,
Maintenance of each nozzle of the print head can be performed smoothly and reliably without soiling the surroundings with ink.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. This inkjet printer is shown in FIG.
As shown in FIG. 2 to FIG. 2, the basic configuration is the same as that of the previously proposed ink jet printer (FIG. 4), but an ink supply pipe (31) connecting the print head 20 and the ink tank 40 and an ink return pipe (33). And a feed pump 32 interposed in the ink supply pipe (31) and a return pump 34 interposed in the ink return pipe (33). The amount of ink discharged from each nozzle 27 of the print head 20 is increased when the amount of ink is greater than the amount of the ink. And a member (70).

The same components as those of the previously proposed ink jet printer shown in FIG. 4 are denoted by the same reference numerals, and the description thereof will be simplified or omitted.

In FIG. 1, a print head 20 has a nozzle unit (20C, 20C) for each color (C, Y, M, B) having a number of nozzles 27 connected to an ink pressure chamber 26.
Y, 20M, 20B) and can reciprocate, for example, by 1/75 inch in the row direction of a print medium (not shown).

Each color nozzle unit (20C, 20Y, 20M, 20B) forming the print head 20 has an ink supply pipe (31) and an ink return pipe (33).
Are connected to the ink tank 40 for each color.

Specifically, the ink supply tube is formed of an ink supply tube 31 made of a synthetic resin having flexibility. The ink return tube is formed of an ink return tube 33 made of a synthetic resin having flexibility. A feed pump (push-type roller pump 32) is interposed in the ink supply tube 31, and a return pump (pull-type roller pump 3) is provided in the ink return tube 33.
4) is interposed. The feed pump 32 (return pump 34) is formed of a roller pump having a plurality (for example, four) of pressing rollers 32R (34R) arranged at predetermined intervals on a circular locus.

In this embodiment, the two pumps (32, 34) are arranged so that the amount of ink sent by the feed pump 32 is larger than the amount of ink returned by the return pump 34 by a set amount.
Is selected.

Here, the above-mentioned "set amount" means that when both pumps (32, 34) are driven simultaneously, the print head 2
0 (20C, 20Y, 20M, 20B) nozzles 27
It is selected so that a sufficient amount of ink can be discharged smoothly for maintenance (prevention of clogging and degassing).

The waste ink receiving member (70) receives the ink ejected from each nozzle 27 of the print head 20 (20C to 20B) and receives a waste ink collection unit (a waste ink cassette 8).
0).

In this embodiment, the print head 20 (20
The waste ink receiving member is formed from the washing board 70 so that the ink discharged from each nozzle 27 of C to 20B) can be effectively used to remove the paper dust attached to the tip of each nozzle 27.

The washing board 70 has a gap G between the facing surface 72 which is surrounded by the convex portion 73 and faces the leading end surface 24 of the print head 20 and the leading end surface 24, for example, 0.1 to 0.5.
mm (preferably, 0.3 mm) and both (2
4, 72), an ink flow is generated, and the ink flow is used to remove paper dust attached to the front end surface 24. The ink flowing on the facing surface 72 is collected in the ink recovery chamber 75 through the discharge port 74 and then discharged through the ink discharge means 90 to the waste ink cassette 80.
To be housed in

The ink discharge means 90 comprises a discharge pipe 76 for connecting (communicating) the washing board 70 and the waste ink cassette 80, and a suction pump 94 interposed in the discharge pipe 76.

In the ink jet printer having such a configuration, when maintenance is performed, both pumps (32, 34) are simultaneously driven so that the amount of ink sent by the feed pump 32 is larger than the amount of ink returned by the return pump 34. You. Then, the pressure loss between the two pumps (32, 34) is absorbed, and the ink is smoothly and reliably ejected from each nozzle 27 of the print head 20 (20C to 20B) to perform maintenance (clogging prevention and gas release). .

At this time, the print head 20 (20C to 20C)
B) Ink discharged from each nozzle 27 (waste ink)
Is reliably received by the washing board 70 and sent to the waste ink cassette 80. Therefore, the nozzles 27 of the print head 20 (20C to 20B) can be smoothly and reliably maintained without soiling the surroundings with ink.

[0027]

According to the present invention, a print head and an ink tank are connected via an ink supply pipe and an ink return pipe, and a feed pump provided in the ink supply pipe is driven to move the print head from the ink tank. The ink in the print head can be returned to the ink tank by driving the return pump interposed in the ink return pipe so that the ink can be supplied to the ink tank, and the amount of ink sent by the feed pump is smaller than the amount of ink returned by the return pump. In most cases, both pumps are formed so that they can be driven simultaneously, and a waste ink receiving member that can receive the ink discharged from each nozzle of the print head and send it to the waste ink collection unit is provided, so that the surroundings are not stained with ink. Maintenance of each nozzle of the print head can be performed smoothly and reliably.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an embodiment of the present invention.

FIG. 2 is a view for explaining a waste ink receiving member.

FIG. 3 is a diagram for explaining a conventional ink jet printer.

FIG. 4 is a diagram for explaining a previously proposed inkjet printer.

[Explanation of symbols]

Reference Signs List 20 print head 20C, 20Y, 20M, 20B nozzle unit for each color 27 nozzle 31 ink supply tube (ink supply tube) 32 feed pump 33 ink return tube (ink return tube) 34 return pump 40 ink tank 70 washing board (waste ink receiver) Member) 80 waste ink cassette (waste ink recovery unit) 90 ink discharge means

Claims (1)

[Claims] A print head having a plurality of nozzles and an ink tank are connected via an ink supply pipe and an ink return pipe, and a feed pump provided in the ink supply pipe is driven to drive ink from the ink tank to the print head. A return pump, which can be supplied and is interposed in the ink return pipe, is driven to form the ink in the print head so that it can be returned to the ink tank, and the amount of ink supplied by the feed pump is made larger than the amount of ink returned by the return pump. An ink-jet printer, wherein both the pumps are formed so as to be driven simultaneously, and a waste ink receiving member is provided which can receive ink discharged from each nozzle of the print head and send it to a waste ink collecting section.