JPH1191127A - Inkjet printer - Google Patents

Abstract

(57) [Summary] To prevent waste of time and ink and to enable smooth ink supply and stable printing operation. [MEANS FOR SOLVING PROBLEMS] A print head (20) and an ink tank (40) are provided. Ink supply tube 31 and ink return tube 33
The ink is supplied from the ink tank 40 to the print head 20 by driving the feed pump 32 interposed in the ink supply tube 31, and the return pump 34 is driven to drive the ink in the print head 20 into the ink tank. 40 and a feed pump 3 with an ink supply tube 31.
A heating means 50 is provided on the downstream side of the ink supply tube 2, the ink temperature is detected by the ink supply tube 31 and / or the ink return tube 33, and the feed pump 3 is set based on the detected ink temperature.
The second ink feed amount and the ink return amount of the return pump 34 were formed so as to be controllable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an ink jet printer capable of supplying ink from an ink tank to a print head via an ink supply 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]

Incidentally, in the ink jet printer proposed above, the printing operation is not always continued without a break, and the non-use state may be continued for a relatively long time. In any case, if the state where there is no ink flow is prolonged, the ink clumps and the like are removed by the filter in the ink tank, but the solidification of the ink adheres to the inner wall surface of the ink pressure chamber (ink buffer) of the print head 20. Or an ink lump is generated and the ink easily floats.

If left unattended, smooth printing is hindered, and dot clogging may occur due to nozzle clogging or non-ejection of ink. Must be performed frequently, which wastes time and ink.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ink jet printer capable of preventing waste of time and ink and performing a stable ink supply and stable printing operation.

[0010]

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 is supplied from the ink tank to the print head and the return pump is driven to drive the ink in the print head back to the ink tank. The ink supply pipe is provided with heating means downstream of the feed pump, and the ink supply pipe is provided. And / or detecting the ink temperature with an ink return pipe, and controlling the ink feed amount of the feed pump and the ink return amount of the return pump based on the detected ink temperature.

In this case, the feed pump and the return pump are simultaneously driven to circulate the ink between the ink tank and the print head. Therefore, the ink circulates in the ink circulation path including the ink tank and the print head which are communicated via the ink supply pipe and the ink return pipe, and the flow is not stopped. And the formation of ink lumps can be prevented. At this time, the ink is heated by the heating means in the ink supply pipe, so that the ink viscosity and fluidity can be maintained well, and the ink circulation can be further facilitated.

Since the nozzles of the print head are not closed during the ink circulation, it is necessary to control the amount of ink supplied by the feed pump and the amount of ink returned by the return pump so that ink does not leak from each nozzle. is there. put it here,
Since the viscosity, volume, etc. of ink changes with temperature, the ink temperature is detected by an ink supply pipe and / or an ink return pipe, and based on the detected ink temperature, the amount of ink supplied by the feed pump and the amount of ink returned by the return pump are determined. Is to be controlled.

Thus, ink can be smoothly circulated between the print head and the ink tank while preventing ink from leaking from the nozzles of the print head. Therefore, time and ink are prevented from being wasted, and smooth ink supply and printing operation can be stably performed.

[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 and FIG. 2, the basic configuration is the same as that of the previously proposed ink jet printer (FIG. 4), except that the heating means 50, the ink temperature detecting means (55), and the pump control means (60) are provided. The ink is maintained at a predetermined temperature between the ink tank 40 and the print head 20 so as to be able to circulate while preventing the ink from leaking from each nozzle 27 of the print head 20.

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 communicating with 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. The ink supply tube 31 is provided with a push-type feed pump 32, and the ink return tube 33 is provided with a pull-type return pump.

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.

The heating means 50 comprises an ink supply tube 31
The heater 51 attached downstream of the feed pump 32
And a controller 52 for controlling ON / OFF of the heater 51 and switching control of the heat generation capacity (current), and is formed so that the ink in the tube 31 can be heated to a predetermined temperature. In this embodiment, the controller 52 performs a control operation by a control signal from the drive control means 60.

The drive control means 60 includes a CPU, ROM, R
The entire printer can be driven and controlled, including an AM, a display (IND), a keyboard (KB), an input / output port (I / O), and the like.

The ink temperature detecting means 55 is a means for detecting the ink temperature with the ink supply tube 31 and / or the ink return tube 33. In this embodiment, the ink temperature detecting means 55 is provided in the ink supply tube 31 and the ink return tube 33. The ink temperature detecting means 55 may be provided in one of the tubes (31, 33).

The pump control means includes an ink temperature detecting means 5
5 based on the ink temperature detected by
And the ink return amount of the return pump 34 can be controlled. In this embodiment, the pump control means is formed using the drive control means 60.

Next, the operation of this embodiment will be described. When the printing operation is temporarily interrupted or the like, the drive control unit 60
The feed pump 32 and the return pump 34 are simultaneously driven to circulate the ink between the ink tank 40 and the print head 20 (20C to 20B). Therefore, the ink is supplied to the ink tank 40 and the print head 20 which are communicated via the ink supply tube 31 and the ink return tube 33.
Since the flow is not stopped by circulating in the ink circulation path including the (ink pressure chamber 26), for example, the print head 20 (20
C to 20B), and the formation of an ink mass and the formation of an ink mass can be prevented. At this time, since the ink is heated by the heating means 50 in the ink supply tube 31,
Ink viscosity and fluidity can be maintained well, and ink circulation can be further facilitated.

During the ink circulation, the print head 20 (20
Since each nozzle 27 of C to 20B) is not closed,
The ink feed amount of the feed pump 32 and the ink return amount of the return pump 34 are controlled so that ink does not leak from each nozzle 27. Further, although the viscosity and volume of the ink change depending on the temperature, the ink temperature is detected by the ink supply tube 31 and the ink return tube 33, and based on the detected ink temperature, the ink feed amount of the feed pump 32 and the return pump 34 The ink return amount is controlled.

Thus, the print head 20 (20C-2)
0B), the ink can be smoothly circulated between the print head 20 (20C to 20B) and the ink tank 40 while preventing ink from leaking from each nozzle 27.

According to this embodiment, the print head 20 (20C to 20B) and the ink tank 40 are connected via the ink supply tube 31 and the ink return tube 33, and the print head 20 (20C to 20B) is interposed in the ink supply tube 31. The feed pump 32 is driven to supply ink from the ink tank 40 to the print head 20 (20C-20B), and the return pump 34 is driven to drive the print head 20 (20C-20B).
The ink inside the ink tank 40 is formed so as to be able to return to the ink tank 40, a heating means 50 is provided downstream of the feed pump 32 by the ink supply tube 31, and the ink temperature is detected by the ink supply tube 31 and / or the ink return tube 33. Since the ink feed amount of the feed pump 32 and the ink return amount of the return pump can be controlled based on the detected ink temperature, time and ink are prevented from being wasted, and smooth ink supply and printing operation can be performed. Can be performed stably.

In this embodiment, the ink temperature is detected by the ink supply tube 31. However, other than the ink supply tube 31, for example, the atmosphere in the vicinity of the ink supply tube 31, the print head 20 and the inside of the machine such as the vicinity of the print head 20. And the temperature of the ink may be detected indirectly.

[0029]

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 is formed so as to be able to supply ink to the ink tank and to return the ink in the print head to the ink tank by driving a return pump. A heating means is provided downstream of the feed pump by an ink supply pipe. The ink temperature is detected at a time, and the ink feed amount of the feed pump and the ink return amount of the return pump can be controlled based on the detected ink temperature, so that time and ink are prevented from being wasted and smooth. Ink supply and printing operation can be performed stably.

[Brief description of the drawings]

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

FIG. 2 is also a diagram for explaining a drive control unit.

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 50 heating means 51 heater 52 controller 55A, 55B Ink temperature detection sensor (ink temperature detection means) 60 Drive control 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. An ink supply pipe is driven to drive the return pump so that the ink in the print head can be returned to the ink tank. A heating means is provided downstream of the feed pump by the ink supply pipe, and the ink is supplied by the ink supply pipe and / or the ink return pipe. An ink jet printer wherein a temperature is detected, and an ink feed amount of a feed pump and an ink return amount of a return pump are controllable based on the detected ink temperature.