JPH04251752A - Ink-jet printer - Google Patents

Abstract

PURPOSE:To purge an ink-jet printer positively through a pump means. CONSTITUTION:A small-sized pump 5 driven on purging is interposed between connecting pipes 6, 7 connecting an ink tank 4 and a printing head 3, a bypass pipe 8 connecting the connecting pipes 6, 7 before and behind the small-sized pump 5 is mounted, one sidewall of the bypass pipe is composed of a flexible film 8a, and pushed by a projecting section 9a on purging, and the bypass pipe 8 is closed, thus preventing the back flow of ink.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet printer.

0002

2. Description of the Related Art As is well known, ink jet printers require a recovery operation (purging) to fill the nozzles of the print head with ink and to remove air bubbles, dirt, and the like. Therefore, as a purging means, conventionally, an ink bag filled with ink is stored in an ink tank, and pressure is applied to this ink bag from the outside by a human operating means (for example, Japanese Patent Application Laid-Open No. 60-204351 There are other methods (for example, Utility Model Application No. 2-40767) in which the ink bag is pressed by an automatic pressing member using a drive source such as a motor instead of the manual means of the conventional method. Ta.

0003

[Problems to be Solved by the Invention] However, since the former method uses manual pressing means, the pressure on the ink is not constant each time it is pressed, and as a result, the flow rate of the ink may change. If the bag was pressed too hard, there was a risk of destroying the ink bag itself or damaging the print head. In addition, in the latter case, a large pressurizing force is required to eject from the nozzle of the print head, which requires a large pressing device, and the pressure changes depending on whether the ink bag is full or when there is a gap. Therefore, there was a drawback that the discharge amount in one operation was not constant. Both the former and the latter are limited to structures in which a bag is filled with ink in advance and stored in a tank.

SUMMARY OF THE INVENTION An object of the present invention is to provide an inkjet printer that can reliably purify a print head and can always supply a constant amount of ink to the print head.

[0005]

[Means for Solving the Problems] A feature of the present invention is that a pump means that is driven during purging is interposed in a connecting pipe that connects an ink tank and a print head, and between the connecting pipes before and after the pump means. are connected by a bypass pipe, and the bypass pipe is provided with means for preventing backflow of ink.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings.

In FIG. 1, during printing, a carriage 1 is guided by carriage guides 2, 2 and slides back and forth in the vertical direction of the drawing, and on this carriage are a print head (ink jet head) 3, An ink cartridge 4 containing an ink tank (not shown) and a small pump 5 as a pump means interposed between the print head and the ink cartridge are mounted. Further, the print head 3 and the small pump 5 are connected by a connecting pipe 6, and this small pump and the ink cartridge 4 are connected by a connecting pipe 7. The two connecting pipes 6 and 7 are connected by a bypass pipe 8, and one side wall of this bypass pipe is
It is constructed from a flexible film 8a. Further, a protrusion 9a is formed on the printer frame 9 close to the home position of the carriage 1 and faces the carriage 1, and an elastic member 10 is attached to the tip of this protrusion.

Next, the operation of the present invention will be explained. FIG. 1 shows the state during printing operation, in which ink is supplied from the ink tank in the ink cartridge 4 to the print head 3 through the bypass pipe 8, and at the same time the carriage 1 is guided to the carriage guides 2, 2. been moved,
Printing is performed on recording paper interposed between a platen (not shown) and a print head 3.

Next, the operation during purging will be explained. When the printing on the recording paper is finished and the carriage 1 returns to the home position, the flexible film 8a collides with the elastic member 10 as shown in FIG. It flexes inwards, so that this bypass pipe 8 is closed by this elastic member. Therefore, the small pump 5 is operated to perform purging while filling the print head 3 with ink from the ink tank of the ink cartridge 4. At this time, since the bypass pipe 8 is closed, the ink flowing through the connecting pipe 6 from the small pump 5 is reliably supplied to the print head 3 without flowing back into the bypass pipe.

In the first embodiment, the ink cartridge 4 may be detachably attached to the carriage 1. The small pump 5 does not necessarily require an airtight structure. Further, the bypass pipe 8 using the flexible film 8a as a backflow prevention means may have a portion that contacts the elastic member 10 as a flexible tube. The shape of the protrusion 9a may be any shape as long as it can close the bypass pipe 8, and the protrusion 9a may be attached to a dedicated actuator independent of the frame 9.

Another embodiment will be described with reference to FIG. 3. The feature of this embodiment is that the backflow prevention means is configured such that the portion connecting the bypass pipe 8 and the connecting pipe 6 is formed in a small diameter portion 81. It is in. It is sufficient that the inner diameter of the small diameter portion 81 is such that when the small pump 5 is operated, the ink does not flow back, or at least is difficult to back flow. Since the other configurations are substantially the same as those of the previous embodiment, the same reference numerals are given.

In this embodiment, the small pump 5 is operated regardless of the position of the carriage 1, and the print head 3 is
Purging can be performed while filling with ink.

Although not shown, a bypass pipe 8a
The backflow prevention means may be configured by providing a one-way valve inside.

[0014]

The inkjet printer of the present invention constructed as described above can perform stable purging using the pump means. And the purging device can be made smaller.
Since the amount of ink discharged in one operation of the pump means is constant, initial ink filling can be performed reliably, and air bubbles and dust can be removed. Furthermore, damage to the print head and ink tank does not occur. Furthermore, the backflow prevention means in the bypass pipe portion can prevent ink from flowing back when the pump means is activated.

[Brief explanation of the drawing]

[Figure 1] Plan view

[Figure 2] Plan view showing purging state

[Fig. 3] Plan view showing another embodiment

[Explanation of symbols]

3 Print head 4 Ink cartridge with built-in ink tank 5 Pump means (small pump) 8 Bypass pipe 9a Backflow prevention device (projection) 10 Backflow prevention device (elastic member) 81 Backflow prevention device (small diameter part)

Claims (1)

[Claims] 1. A pump means that is driven during purging is interposed in a connecting pipe that connects an ink tank and a print head, and the connecting pipes before and after the pump means are connected by a bypass pipe. An inkjet printer characterized in that the pipe is provided with a backflow prevention means for preventing backflow of ink.