JP3127581B2 - Ink jet recording apparatus and operation method - Google Patents

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 pigment of ink, the pigment sediments at the bottom of the ink tank upon standing and the ink density changes to make the ink non-uniform. When ink jet recording is performed using an ink whose physical properties such as density, temperature, and specific gravity change when left in such a manner, it is necessary to agitate the ink.

[0003] In a conventional ink jet recording apparatus, a stirrer rotatably driven by a motor is provided in an ink tank, and a stirrer attached to the tip of the stirrer, for example, a fan is connected to the ink tank. As shown in Japanese Patent Publication No. 60-110458 shown in FIG. 8, the rotor 123 is rotated in the ink using a magnet stirrer 124 to mechanically generate a swirling ink flow, thereby causing a disturbance. There was something to do.

Japanese Patent Application Laid-Open No. 60-137655 and Japanese Patent Application Laid-Open No.
As in the case of 83561, only an ink channel for circulating the inside of the head and the ink tank is provided, and ink generated by circulating the ink by the pump is guided to the ink tank and eliminated. FIG. 9 schematically shows the flow path in that case, in which the first tank 113 and the supply chamber 10 are provided.
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
In order to eliminate bubbles in the supply chamber 03 or the supply chambers 104 and 105, and to eliminate clogging of the nozzles (not shown), ink is pressurized by the pump 108 to perform ink circulation or nozzle cleaning.

[0005]

However, in the conventional stirring method using a stirring rod or a magnet stirrer, a device for stirring, for example, a stirring rod, a rotor, a motor, a magnet, or the like is used. Is required, the size of the recording apparatus is increased. In addition, costs are increased.

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

When the ink in the ink tank is agitated by using an ink circulation path for eliminating air bubbles in the head, the ink having settled and has a high density must be circulated in the head. In the case of an ink using a pigment such as a pigment, there is a high possibility that the flow path and the nozzle in the inkjet head are clogged. Furthermore, 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 long circulation time is required.

[0008]

In order to stir the ink in the ink tank uniformly and in a short time, the ink jet recording apparatus according to the present invention forms ink dots by discharging ink droplets from nozzles. A recording head,
An ink tank for storing ink supplied to the recording head, a first supply passage connecting the recording head to the ink tank, a valve provided in the first supply passage, and a first valve upstream of the valve or the valve. It is characterized by comprising a second supply flow path branched from the middle of the supply flow path and connected to the ink tank, and a pump attached to a flow path upstream of the branch point.

In the above ink jet recording apparatus, the valve selectively shuts off the ink flow to the first supply flow path during non-printing by causing the valve to selectively operate.
It is characterized in that the ink is caused to flow in the supply flow path to circulate the ink in the ink tank.

[0010] Further, in the ink jet recording apparatus, a third supply channel for connecting the ink tank and the ink jet head is further provided.

[0011]

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 first and third supply channels 9 and 6 for supplying ink, so that the ink can be circulated. An ink flow path is formed. The first and third supply channels 10 and 6 are connected to the ink tank 3, and the second supply channel 7 is connected to the ink tank 3.
Is connected to the three-way valve 5 via the tube pump 4. These ink tank 3 and first supply channel 1
0, the three-way valve 5, the first supply flow path 9, the ink jet head 1, the third supply flow path 6, and the ink tank 3 can circulate ink.

On the other hand, the three-way valve 5 is further provided with a second supply channel 7, which is connected to the ink tank 3. Thereby, the ink can be circulated through the ink tank 3, the first supply flow path 9, the three-way valve 5, and the second supply flow path 7.

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

The ink jet head 1 is composed of a nozzle plate 18 for forming the nozzles 2, a frame 17 for forming the ink flow path, and a base 16 for fixing the piezoelectric element 11, and the respective parts are superposed and adhered. I have. The hatched portion represents the ink flow path in three dimensions.

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 first supply passage 9 is provided in the supply chamber 12a.
However, a third supply channel is joined to the supply chamber 12b,
The ink is supplied to the first supply channel 9, the supply chamber 12a, the cavity 1
3, the supply chamber 12b, and the third supply flow path 6 can flow in this order. Alternatively, the pump can be reversely driven to flow in the opposite direction.

Each of the nozzles 2 is provided with a piezoelectric element 11. The deformation of the piezoelectric element 11 by applying an electric charge changes the volume of the cavity 13, and extrudes ink from the nozzle to eject recording dots.

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 volume of the cavity and ejecting ink from nozzles to form recording dots.

FIG. 4 is a diagram schematically showing the ink flow path of the embodiment described with reference to FIGS. 1, 2 and 3, and showing the second supply flow path.

The flow of ink in the second supply flow path 7 flows out of the first supply flow path 30 attached through the first supply port 32 of the ink tank 34 as shown by the arrow, and
Pressurized by the second supply flow path 28 via the three-way valve 26
And flows into the ink tank 34 again. By continuing this circulation for a fixed period of time, the ink stored in the ink tank 34 is gradually stirred to a uniform concentration.

In order to shorten the time from the reception of print data to the start of printing and the printing speed, the ink is circulated using the second supply flow path and the ink in the ink tank is stirred. It is best to do it only immediately after However, since the ink jet recording apparatus may be left for a long time in a state where the power is turned on, a timer may be provided in the ink jet recording apparatus, and the operation may be periodically performed with a 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 supply flow path.

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

Although the embodiment using the three-way valve for controlling the flow rate of the first supply flow path and the second supply flow path has been described above, other methods for controlling the flow rate are also possible. FIG. 3 is a schematic view showing an embodiment using a valve for opening and closing a valve.

An opening / closing valve 26a is provided in the first supply flow path 24, and an ink jet head 19 is connected from a branch point 26b.
Can be blocked. On-off valve 26
When a is closed, the ink flow at the branch point 26a flows as indicated by the arrow X, and flows to the second supply flow path. When the on-off valve 26a is opened, the second supply flow path 28a is designed to have a larger flow resistance than the first supply flow path 27a. The flow is to flow path 24.

FIG. 7 is a perspective view of an embodiment when 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 able to reciprocate in the axial direction.
The drive belt 41 is stretched in parallel with the carriage shaft 45 by pulleys 42 and 43. The pulley 43 has a stepping motor 44 attached thereto.
Is rotated to operate the carriage 40.

On the other hand, the ink cartridge 46 is detachable and is mounted 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 supply
The ink inside is taken out. Further, the first supply channel 54
Is connected to the gear pump 51, and the gear pump 51 is
The ink can be sent to the three-way valve 52 by the supply channel 55. A first supply channel 56 and a second supply channel 57 are connected to the three-way valve 52. The first supply channel 56 is connected to the carriage ink tank 38, and the second supply channel 57 is connected to the supply pin 48.
Connected to each other. In this apparatus, the first supply channel 56 only supplies ink to the carriage tank 38 and the ink jet head 37, and when the ink is stirred, the ink cartridge 46 and the supply pin 4
7, a first supply flow path 54, a gear pump 51, a first supply flow path 55, a three-way valve 52, a second supply flow path 57, and a supply pin 48. The ink in the ink cartridge 46 is circulated by driving the gear pump 51. It is possible to perform agitation.

[0031]

According to the present invention, there is provided an ink jet recording head for ejecting ink droplets from nozzles to form recording dots in order to stir the ink in an ink tank uniformly and in a short time. An ink tank for storing ink supplied to the recording head, a first supply passage connecting the recording head to the ink tank, a valve provided in the first supply passage, and a first valve upstream of the valve or the valve. Providing a second supply flow path that branches off from the middle of the supply flow path and connects to the ink tank, and a pump attached to the flow path upstream of the branch point causes clogging with only one valve There is an effect that the ink in the ink tank can be circulated and uniformly stirred without sending a possibly high-density ink to the ink jet head.

In addition, the ink jet recording apparatus further includes a third supply flow path for connecting the ink tank to the ink jet head, so that high density ink which may cause clogging with only one valve is used. The ink in the ink tank can be circulated and uniformly stirred without being sent to the ink jet head, and the ink can be circulated in the order of the first supply channel, the recording head, and the third supply channel. Therefore, it is possible to achieve the above-described operation and effect, and at the same time, it is possible to eliminate bubbles generated in the cavity and the supply chamber toward the ink tank.

[Brief description of the 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 illustrating a flow path in the inkjet head.

FIG. 3 is a sectional view of the inkjet head of FIG. 2;

FIG. 4 is a schematic view showing a second supply flow path in FIG. 1;

FIG. 5 is a schematic diagram illustrating a first supply flow path of FIG. 1;

FIG. 6 is a schematic view of an embodiment using an on-off valve.

FIG. 7 is a perspective view of an embodiment of a serial inkjet recording apparatus.

FIG. 8 is an explanatory view of a conventional example in which stirring is performed using a magnet stirrer.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ink jet head 2 Nozzle 3 Ink tank 4 Tube pump 5 Three-way valve 6 Third supply flow path 7, 9, 24, 27, 30 First supply flow path 10, 28 Second supply flow path 19 Ink jet head 20, 21 Supply chamber 22 Cavity 23 Nozzle 25 Third supply flow path 26 Three-way valve 26a Open / close valve 26b Branch point 29 Tube pump 31 Second supply port 32 First supply port 33 Third supply port 34 Ink tank

Claims (3)

(57) [Claims] An ink jet recording head for ejecting ink droplets from nozzles to form recording dots; an ink tank for storing ink supplied to the recording head; and a first connecting the recording head and the ink tank. a supply passage, a valve provided in the first supply passage, some have the valve
Is in the middle of the first supply flow path upstream of the valve
An ink jet recording apparatus characterized by comprising a second supply passage that connects the al branch to the ink tank, and a pump mounted on the upstream side of the flow passage from the branch point. 2. The non-printing valve according to claim 1, wherein the non-printing operation is performed by selectively operating the valve to shut off an ink flow rate to the first supply flow path, and to flow the ink to the second supply flow path. 2. The method according to claim 1, wherein the ink in the tank is circulated. 3. The ink tank and the ink jet
A third supply channel for connecting the head is further provided.
The ink jet recording apparatus according to claim 1, wherein: