JPH068465A - Ink jet recording device and operation method - Google Patents

Abstract

PURPOSE:To agitate ink in an ink tank without sending ink to an ink jet head. CONSTITUTION:An ink jet recording device is composed of an ink jet recording head 1, an ink tank 3 storing ink, a first flow path 9 connecting the head 1 with the tank 3, a second flow path 7 which branches off from a point on the way of the first flow path 9 and which is in communication with the ink tank, a pump 4 mounted between the flow path branching point and the ink tank, and a means of regulating ink which flows to the first flow path 9, wherein the ink which flows to the first flow path is cut off by a three way valve 5 which acts as a regulating means in order to execute ink circulation through the second flow path 7 and the ink tank 3.

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.

[0002]

2. Description of the Related Art When a pigment is used as a dye for ink, the pigment is allowed to settle on the bottom of an ink tank when left to stand, resulting in a change in ink density and non-uniformity. When ink-jet recording is performed using an ink whose physical properties such as density, temperature, and specific gravity change when left as described above, it is necessary to stir the ink.

In a conventional ink jet recording apparatus, a stirrer rotatably driven by a motor is provided in an ink tank, and a stirrer member attached to the tip of the stirrer, for example, a fan, is provided in the ink. In addition, as shown in Japanese Patent Publication No. 60-110458 shown in FIG. 8, the rotor 123 is rotated in the ink using the magnetic stirrer 124 to mechanically generate a swirling ink flow to stir the ink. There was something to do.

Further, as a device having a flow path for circulating ink, there is disclosed in JP-A-60-137655 and JP-A-3-1.
As in 83561, only an ink flow path that circulates in the head and the ink tank is provided, and ink is circulated by a pump to introduce and eliminate bubbles generated in the head to the ink tank. FIG. 9 schematically shows the flow path in that case. The first tank 113 and the supply chamber 10 are shown in FIG.
4, the flow path is configured so that the ink circulates via the inkjet heads 101, 102, 103, the supply chamber 105, and the pump 108. Heads 101, 102, 1
No. 03 or the supply chambers 104 and 105, or ink is circulated or nozzle cleaning is carried out by pressurizing the ink by the pump 108 in order to eliminate clogging of the nozzle, which is not shown in the figure.

[0005]

However, in the conventional stirring method using the stirrer or the magnetic stirrer, a device for the stirrer, for example, the stirrer, the rotor, the motor or the magnet is used. However, the size of the recording device is increased because of the necessity. In addition, the cost is high.

Further, in order to generate a swirling ink flow,
There was a problem that the flow velocity difference in the ink tank was large and there was a high possibility that a part that was not stirred was generated.

When the ink in the ink tank is agitated by using the ink circulation path for eliminating the air bubbles in the head, the ink having a sedimentation and a high density must be circulated in the head. In the case of an ink using a dye such as a pigment, there is a high possibility that the flow path or nozzle in the inkjet head will be clogged. Further, since the flow path in the head is formed finely, there is a problem that a high pump pressure is required to circulate the ink and a circulation time needs to be lengthened.

[0008]

In order to solve the above problems and to stir the ink in the ink tank uniformly and in a short time, the present invention provides a first flow path connecting the ink jet head and the ink tank. In addition, branch from the middle of the first flow path,
It has a second flow path realized by a flow path connected to the ink tank, and is made to flow by using a pump to circulate only the ink in the ink tank to perform stirring.

[0009]

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

FIG. 1 is a perspective view showing an embodiment in which a three-way valve and a tube pump are used.

An ink jet head 1 having a plurality of nozzles 2 for ejecting recording dots is provided with supply pipes 6 and 9 for supplying ink, and an ink flow path is formed so that ink can circulate. ing. The supply pipe 6 is connected to the ink tank 3, and further, the supply pipe 7 is connected to the ink tank 3 and is connected to the three-way valve 5 via the tube pump 4. The supply pipe 9 is attached to connect the three-way valve 5 and the inkjet head 1. Ink can be circulated by the inkjet head 1, the supply pipe 6, the ink tank 3, the supply pipe 7, the tube pump 4, the three-way valve 5, and the supply pipe 9, and constitutes a first flow path.

On the other hand, the three-way valve 5 is further provided with a supply pipe 1
0 is attached and connected to the ink tank 3. As a result, the ink can be circulated by the ink tank 3, the supply pipe 7, the tube pump 4, the three-way valve 5, and the supply pipe 10 to form the second flow path.

FIG. 2 is a sectional view showing a flow path in the ink jet head.

The ink jet head 1 comprises a nozzle plate 18 for forming the nozzles 2, a frame 17 for forming an ink flow path, and a base 16 for fixing the piezoelectric element 11. Each component is laminated and adhered. There is. Moreover, the shaded portion three-dimensionally represents the ink flow path.

FIG. 3 is a sectional view of the ink jet head shown in FIG.

Each nozzle has a cavity 13, and supply chambers 12a and 12b are formed so as to cross the cavities in order to supply ink to the plurality of cavities. Further, the supply pipe 9 is provided in the supply chamber 12a,
The supply pipe 6 is joined to the supply chamber 12b, and ink can flow in the order of the supply pipe 9, the supply chamber 12a, the cavity 13, the supply chamber 12b, and the supply pipe 6. Alternatively, the pump can be driven in the reverse direction so that the flow can be reversed.

Each nozzle 2 is provided with a piezoelectric element 11, and the volume of the cavity 13 is changed by the deformation of the piezoelectric element 11 by applying an electric charge, and ink is pushed out from the nozzle to eject a recording dot.

Instead of the piezoelectric element 11, a heating element may be attached to the vibrating portion 13a in the cavity 13 to generate bubbles, thereby changing the cavity volume and ejecting ink from the nozzle to form a recording dot.

FIG. 4 is a view schematically showing the ink flow path of the embodiment described in FIGS. 1, 2 and 3 and showing the second flow path.

The ink flow in the second flow path flows out from the supply pipe 30 attached through the supply port 32 of the ink tank 34 as shown by the arrow, is pressurized by the pump 29, and is supplied via the three-way valve 26. 28, and again flows into the ink tank 34. By continuing this circulation for a fixed time, the ink stored in the ink tank 34 is gradually stirred to a uniform density.

In order to shorten the time from the reception of print data to the start of printing and the printing speed, the ink circulation using the second flow path and the agitation in the ink tank were turned on. It is best done only immediately. However, since it may be left for a long time while the power is on, it is possible to provide a timer in the ink jet recording apparatus and periodically perform the minimum number of times according to the physical properties of the ink.

FIG. 5 is a view schematically showing the ink flow path of the embodiment described with reference to FIGS. 1, 2 and 3 and showing the first flow path.

The ink flow in the first flow path flows as indicated by the arrow, and the ink sucked from the ink tank 34 through the supply port 30 by the operation of the pump 29 is supplied to the supply pipe 27, the three-way valve 26, and the supply pipe. It is sent to the supply chamber 21 by 24, passes through all cavities in a dispersed manner, and is sent again from the supply chamber 19 to the ink tank 34 through the supply pipe 25. Since the ink tank is open to the atmosphere, by performing such circulation for a fixed time, the bubbles generated in the cavity and the supply chamber are guided to the ink tank and removed to the atmosphere.

Although the embodiment using the three-way valve for controlling the flow rate of the first flow path and the second flow path has been described above, another method can be used as a means for controlling the flow rate. It is a schematic diagram showing an example using a valve.

An opening / closing valve 26a is provided in the flow path 24 so that the ink flow from the branch point 26b to the ink jet head 19 can be shut off. When the on-off valve 26a is closed, the ink flow at the branch point 26a flows as shown by the arrow X, and becomes the flow of the second flow path. When the opening / closing valve 26a is opened, the flow path 28a is designed to have a flow path resistance larger than that of the flow path 27a.
As described above, the flow becomes the flow of the first flow path.

FIG. 7 is a perspective view of an embodiment in which the present invention is realized by a serial ink jet recording apparatus.

The ink jet head 37 and the carriage ink tank 38 are fixed to a carriage 40, and the carriage 40 is supported by a drive belt 41 and a carriage shaft 45 so as to be reciprocally movable in the axial direction.
The drive belt 41 is stretched by pulleys 42 and 43 in parallel with the carriage shaft 45. A stepping motor 44 is attached to the pulley 43,
Is rotated to operate the carriage 40.

On the other hand, the ink cartridge 46 is removable and is installed while being guided by the cartridge guide 49. When completely installed, the supply pins 47 and 48 attached to the cartridge guide are inserted into the cartridge 46, and the ink in the ink cartridge 46 is taken out by the supply pipes 54 and 57. Furthermore, supply pipe 5
4 is connected to a gear pump 51, and the gear pump 51 can send ink to the three-way valve 52 by a supply pipe 55. Two supply pipes are connected to the three-way valve 52, and the supply pipe 56 is connected to the carriage ink tank 38.
The supply pipes 57 are connected to the supply pins 48, respectively. In this device, the first flow path does not circulate ink, and the carriage tank 38 and the inkjet head 3
7 only to supply ink, and the second flow path is constituted by the ink cartridge 46, the supply pin 47, the supply pipe 54, the gear pump 51, the supply pipe 55, the three-way valve 52, the supply pipe 57 and the supply pin 48, and the gear pump 51. The ink in the ink cartridge 46 can be circulated and agitated by driving the.

[0029]

INDUSTRIAL APPLICABILITY The present invention has a simple structure in an ink jet recording apparatus requiring agitation, by providing a second flow path through which ink in an ink tank can be circulated without using an ink jet head. Moreover, it is possible to circulate the ink in the ink tank and evenly stir it without sending the high-concentration ink that may cause clogging when passing through the inkjet head to the inkjet head. to enable.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment using a three-way valve and a tube pump.

FIG. 2 is a cross-sectional view showing channels in an inkjet head.

3 is a cross-sectional view of the inkjet head of FIG.

FIG. 4 is a schematic diagram showing a second flow path in FIG.

FIG. 5 is a schematic diagram showing a first flow path in FIG.

FIG. 6 is a schematic diagram of an example using an on-off valve.

FIG. 7 is a perspective view of an example of a serial inkjet recording device.

FIG. 8 is an explanatory diagram of a conventional example in which a magnetic stirrer is used to perform stirring.

FIG. 9 is a schematic diagram of a conventional example having an ink flow path for circulating ink.

[Explanation of symbols]

 1 Inkjet head 2 Nozzle 3 Ink tank 4 Tube pump 5 Three-way valve 6, 7, 9, 10 Supply pipe 19 Inkjet head 20, 21 Supply chamber 22 Cavity 23 Nozzle 24, 25 Supply pipe 26 Three-way valve 26a Open / close valve 26b Branch point 27 , 28, 30, 32, 33 Supply pipe 29 Tube pump 34 Ink tank

Claims (3)

[Claims] 1. An inkjet recording head for forming recording dots by ejecting ink droplets from a nozzle, an ink tank for storing ink to be supplied to the inkjet head, and a first connecting the inkjet head and the ink tank. A flow path and a second branch that branches from the middle of the flow path and is connected to the ink tank without passing through the inkjet head
An ink jet recording apparatus comprising: a flow path; and a pump mounted on the flow path that connects a branch point of the flow path and the ink tank. 2. The ink jet recording apparatus according to claim 1, further comprising means for selectively controlling a flow rate of ink to the first flow path. 3. A valve is used as a means for controlling the flow rate of ink to the first flow path, and the valve is selectively operated during non-printing to shut off the ink flow rate to the first flow path. 3. The method for operating an inkjet recording apparatus according to claim 2, wherein the ink is caused to flow in the two flow paths to circulate the ink in the ink tank.