JP3372843B2 - Ink jet recording device - 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 for recording on a recording medium by ejecting ink from the recording head while reciprocating a carriage portion holding the recording head. More specifically, it relates to an inkjet recording apparatus having an ink flow path for supplying ink to a sub tank by using a negative pressure generating pump.

[0002]

2. Description of the Related Art FIG. 6 is a plan view showing a conventional ink jet recording apparatus, and FIG. 7 is a front view of the conventional ink jet recording apparatus shown in FIG.

As shown in FIGS. 6 and 7, a conventional ink jet recording apparatus 101 includes six recording heads 10.
2 is mounted on the carriage 103, the two pulleys 10
It is arranged so as to be coupled to one portion of the timing belt 105 which is wound around 6a. Therefore, by rotating one of the pulleys 106a by the carriage drive motor 106 in the forward and reverse directions, the carriage 103 moves in the direction of arrow A.
It is configured to reciprocate in any direction. On the other hand, the recording medium 104 to be printed by the recording head 102 is
The sub-scanning roller 107 conveys the recording head 102 to a position facing the nozzle.

The ink jet recording apparatus 101 is provided with a main board 108 which functions as a control unit for controlling printing operation and the like. The main board 108 is connected to the recording head 102 by a flexible cable 109. Each of the recording heads 102 is provided with a nozzle (not shown) for ejecting ink, and a heating element (not shown) for heating the ink in the nozzle to cause the film in the ink in the nozzle portion to boil. Main board 10
When the heating element is driven based on the electric signal transmitted from 8 to cause the ink in the nozzle to film-boil, a bubble is generated in the nozzle, and the ink is ejected from the nozzle as the bubble grows.

Further, the ink jet recording apparatus 101 is provided with six main tanks 110 which are ink supply sources and stores inks of six colors (cyan, magenta, yellow, black, cyan light color, magenta light color).
Further, the carriage 103 is provided with six sub-tanks 111 corresponding to each recording head 102. Each main tank 110 and each sub tank 111 are connected by a tank tube 113 arranged inside a caterpillar 112, and each sub tank 111 and each recording head 102 are connected by a head tube 119. Therefore, ink of different colors is ejected from each recording head 102.

The joint 116 to which the negative pressure tube 117 is connected has a first connecting tube 114 and a second connecting tube 114.
Is connected to the connection tube 115. The first connection tube 114, the second connection tube 115, and the negative pressure tube 117 are in communication with each other in the joint 116. The first connecting tube 114 is the sub tank 1
The second connection tube 115 is connected to another sub-tank 111 adjacent to the sub-tank 111.

The negative pressure tube 117 is arranged in the caterpillar 112 and is connected to a head recovery unit 118 and a waste ink tank 120 (see FIG. 8) provided in the ink jet recording apparatus 101. The head recovery unit 118 forcibly ejects ink from the nozzles of the recording head 102 to maintain the ink ejection characteristics of the recording head 102.

The ink contained in the main tank 110 is temporarily held in the sub tank 111 and supplied to the recording head 102. Then, the recording head 102 is driven based on the recording signal from the main board 108 while repeating the conveyance of the recording medium 104 by the sub-scanning roller 107 at a predetermined pitch and the reciprocating movement of the carriage 103. Ink is ejected from 102 to form an image on the recording medium 104. And
When the ink in the sub-tank 111 is consumed by the ejection of the ink from the recording head 102 and the ink remaining amount in the sub-tank 111 becomes small, the ink is replenished from the main tank 110 to the sub-tank 111.

Next, ink replenishment from the main tank 110 to the sub tank 111 will be described with reference to FIG. FIG. 8 is a diagram showing ink flow paths in the conventional inkjet recording apparatus shown in FIGS. 6 and 7. However, in FIG. 8, the six main tanks 110 provided in the conventional inkjet recording apparatus 101 shown in FIG.
And one negative pressure tube 1 of the sub tank 111
Two sub-tanks 111a, 111b connected to 17
And two main tanks 110a and 110b connected to those sub tanks 111a and 111b.

First, the structure of the ink flow path in the conventional ink jet recording apparatus will be described.

The sub-tanks 111a and 111b are connected to the main tanks 110a and 1b by a tank tube 113.
It is connected to 10b. The end of the tank tube 113 on the side connected to the sub tanks 111a and 111b is
It is inserted in the sub tanks 111a and 111b.

In addition, the two sub tanks 111a and 111
b, the first connection tube 114 is connected to the upper part of one sub tank 111a, and the other sub tank 11a
The second connection tube 115 is connected to the upper portion of 1b. The first connection tube 114 and the second connection tube 115 are connected to the joint 116, and the negative pressure tube 117 connected to the joint 116 is connected to the head recovery unit 118 and the waste ink tank 120. The joint 116 is the sub tank 111a,
It is arranged above 111b. Further, the negative pressure tube 117 is provided with a negative pressure generating pump 125 which is a negative pressure generating means, and by driving the negative pressure generating pump 125, the air in the sub tanks 111a and 111b is sucked.

A head tube 119 is connected to the bottom of each of the sub-tanks 111a and 111b, and is connected to the recording head 102 (only one is shown). In addition, the first connection tube 114, the second connection tube 115,
The head tube 119 has a flow passage opening valve 122 that is driven by a driving device (not shown) to open and close the ink flow passage.
a, 122b, 123a, 123b are provided.
Furthermore, on the upper part of each sub tank 111a, 111b,
Atmosphere release valve 124 driven by a drive device (not shown)
a and 124b are provided. Also, each sub tank 1
A liquid amount sensor 121 including electrodes 121a and 121b is provided on each of 11a and 111b.

Here, the joint 116 and each tube 1
A connection structure with 14, 115, 117 will be described with reference to FIG. 9 is a cross-sectional view of the joint and the like shown in FIG. 8 taken along the line BB.

As shown in FIG. 9, the joint 116 is
It has a hollow portion 116a and connection ports 116b, 116c, and 116d communicating with the hollow portion 116a. Connection port 11
The first connection tube 114 is connected to 6b, and the second connection tube 115 is connected to the connection port 116c. Further, a negative pressure tube 117 is connected to the connection port 116d. Therefore, each tube 114, 11
5, 117 are communicated with each other through the hollow portion 116a.

Next, the operation of replenishing ink from the main tank 110 to the sub tank 111 will be described.

In the ink jet recording apparatus constructed as described above, the sub tank 11 is constituted by the flow rate sensor 121.
When it is detected that the amount of ink remaining in the ink tanks 1a and 111b is small, the ink refill operation from the main tanks 110a and 110b to the sub tanks 111a and 111b is started.

First, the case where ink is replenished in the sub tank 111a to which the first connection tube 114 is connected will be described.

From the flow sensor 121 to the main board 108
When the ink remaining amount signal in the sub tank 111a is sent to the sub tank 111a (see FIG. 6 and the like), the flow path opening valves 123a and 122b and the atmosphere opening valve 124a are closed, and the sub tank 111a is closed.
Is sealed to the atmosphere. After that, the negative pressure generating pump 1
When 25 is driven to suck the air in the sub tank 111a, the inside of the sub tank 111a becomes a negative pressure, and the ink in the main tank 110a is supplied to the sub tank 111a. Since the ink is a conductive substance, the liquid volume sensor 121
When both of the electrodes 121a and 121b of the above contact the ink, electricity flows between both electrodes, and it is detected that the sub tank 111a is filled with the ink. Then, a detection signal is sent to the main board 108, an instruction to stop the negative pressure generation pump 125 is issued from the main board 108, and the negative pressure generation pump 125 is stopped.

The negative pressure generating pump 125 is automatically stopped after being driven for a certain period of time. Therefore, although the sub-tank 111a is filled with ink, the negative pressure generating pump 1 may be damaged due to some trouble.
Even if 25 is not stopped, the negative pressure generating pump 12 is supplied after the ink is additionally supplied to the sub tank 111a.
5 stops. At that time, the excess ink supplied is discharged to the waste ink tank 120 through the first connection tube 114, the joint 116, and the negative pressure tube 117.

Next, a case where ink is replenished in the sub tank 111b to which the second connecting tube 115 is connected will be described.

From the flow sensor 121 to the main board 108
When the ink remaining amount signal in the sub tank 111b is sent to the sub tank 111b (see FIG. 6), the flow path opening valves 122a and 123b and the atmosphere opening valve 124b are closed, and the sub tank 111b is closed.
Is sealed to the atmosphere. After that, the sub tank 111
Similarly to the case where ink is replenished in a, when the negative pressure generating pump 125 is driven to suck the air in the sub tank 111b, the ink in the main tank 110b is supplied to the sub tank 111b. When the sub tank 111a is filled with ink, the electrodes 121a, 12 of the liquid quantity sensor 121 are
Electricity flows between 1b and it is detected that the sub tank 111a is filled with ink. Then, the main board 10
8, the main board 108 issues an instruction to stop the negative pressure generation pump 125, and the negative pressure generation pump 125 stops.

Since the negative pressure generating pump 125 is configured to automatically stop after being driven for a certain period of time,
For the same reason as described above, the sub tank 11
When the ink is excessively supplied into 1b, the excessively supplied ink is discharged to the waste ink tank 120 through the second connection tube 115, the joint 116, and the negative pressure tube 117.

As described above, in the conventional ink jet recording apparatus, one negative pressure generating pump 125 is used to supply ink to the six sub tanks 111, so that one negative pressure generating pump 125 is used for one sub tank. Since the number of parts can be reduced as compared with the configuration that supplies ink to the device, the cost of the device is reduced and the size of the entire device is reduced.

[0025]

However, in the conventional ink jet recording apparatus described above, as shown in FIG. 8, the joint 116 includes the sub tanks 111a and 11a.
Since it is arranged at a position higher than 1b, when the extra ink is supplied to the sub tanks 111a and 111b, the first connection tube 114 from the sub tank 111a.
The ink sent to the hollow part 116a (see FIG. 9) in the joint 116 through the ink and the ink sent to the hollow part 116a in the joint 116 from the sub tank 111b through the second connection tube 115 Hollow part 116a
Mixed in.

After that, the negative pressure generating pump 125 is stopped,
The negative pressure inside the negative pressure tube 117 disappears and the negative pressure tube 1
When the air pressure inside 17 becomes equal to the atmospheric pressure, the joint 1
The ink mixed in the 16 hollow portions 116a is supplied to both sub tanks 111a, 1a connected to the joint 116.
Backflow into 11b. Therefore, the sub tank 11
Ink of a color different from the original color of the ink stored in 1a and 111b flows into the sub tanks 111a and 111b,
Then, the mixed ink is ejected from the recording head 102 through the head tube 119.

Then, the color of the ink ejected onto the recording medium 104 (see FIG. 6) by the recording head 102 becomes
It is different from a predetermined color (one of the six colors of cyan, magenta, yellow, black, cyan light color, and magenta light color), and an image different from the image to be recorded is formed, so-called "mixed color". There was a problem.

Therefore, an object of the present invention is to provide an ink jet recording apparatus in which the mixed ink does not flow into the sub tank.

[0029]

In order to achieve the above object, an ink jet recording apparatus of the present invention comprises a plurality of recording heads for recording ink on a recording medium by ejecting ink from nozzles. A plurality of sub-tanks that are connected and temporarily hold ink supplied from the ink supply source to the recording head; connection tubes respectively connected to the sub-tanks;
Negative pressure tube connected to negative pressure generating means for making negative pressure
And a plurality of the connection tubes and the negative pressure tube
A negative pressure generating means, which has a connecting portion for communication.
Is used to supply ink to the plurality of sub-tanks.
A jet recording device, wherein the connecting part is
It is characterized by being placed at a position lower than the buttank .

According to the ink jet recording apparatus constructed as described above, when the negative pressure generating means is driven, the inside of the sub tank becomes negative pressure, and ink is replenished from the ink supply source to the sub tank. At this time, if excess ink is supplied to each sub-tank due to some trouble, the ink discharged from one sub-tank and the ink discharged from the other sub-tank will be connected at the connection between the negative pressure tube and each connection tube. Mixed. However, since the connecting portion is installed at a position lower than each sub tank, the ink mixed in the connecting portion does not flow back into each sub tank.

The negative pressure generating means is driven for a fixed time.
It may be configured to be automatically stopped later. Also, a plurality of the connection tube and the negative pressure tube,
It may be configured such that they are connected to each other through a joint means having a hollow portion.

Furthermore, a plurality of the connection tubes and the negative
The pressure tube and the pressure tube may be directly connected in a state of communicating with each other.

Further, there is provided a plurality of units each including a plurality of the sub-tanks respectively connected to the respective recording heads and the negative pressure tubes connected to the respective sub-tanks through the plurality of connection tubes. May be

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a plan view showing an embodiment of the ink jet recording apparatus of the present invention, and FIG. 2 is a front view of the ink jet recording apparatus shown in FIG.

As shown in FIGS. 1 and 2, in the ink jet recording apparatus 1 of this embodiment, the first connecting tube 14, the second connecting tube 15 and the negative pressure tube 17 are provided.
The joint 16 to which is connected is arranged at a position lower than the sub tank 11. In the inkjet recording apparatus 1 of the present embodiment shown in FIGS. 1 and 2, the recording head 2, the carriage 3, the timing belt 5, the carriage drive motor 6, the pulley 6a, the sub-scanning roller 7, the main board 8, the flexible cable. 9, main tank 1
0, the sub-tank 11, the caterpillar 12, the tank tube 13, the head recovery unit 18, and the head tube 19 are the same as those of the conventional inkjet recording apparatus 101 shown in FIG.

In the ink jet recording apparatus 1 of this embodiment, the ink contained in the main tank 10 which is an ink supply source is temporarily held in the sub tank 11 and supplied to the recording head 2 as in the conventional ink jet recording apparatus. To be done. Then, the recording head 2 is driven based on the recording signal from the main board 8 while repeating the conveyance of the recording medium 4 by the sub-scanning roller 7 at a predetermined pitch and the reciprocating movement of the carriage 3, thereby recording the recording head 2. Ink is ejected from 2 to form an image on the recording medium 4. Then, when the ink in the sub-tank 11 is consumed by the ejection of the ink from the recording head 2 and the remaining ink amount in the sub-tank 11 becomes small, the ink is replenished from the main tank 10 to the sub-tank 11.

Next, from the main tank 10 to the sub tank 1
Ink replenishment for No. 1 will be described with reference to FIG.

FIG. 3 is a diagram showing ink flow paths in the ink jet recording apparatus shown in FIGS. 1 and 2. However, in FIG. 3, two sub-tanks 11a and 11b connected to one negative pressure tube 17 among the six main tanks 10 and sub-tanks 11 provided in the inkjet recording apparatus 1 shown in FIG. , Two main tanks 10 connected to those sub-tanks 11a, 11b
a and 10b are shown. Further, the waste ink tank 20, the liquid amount sensor 21, the electrodes 21a and 21b, the flow path opening valves 22a, 22b, 23a and 23b, and the atmosphere opening valve 24 shown in FIG.
The configurations of a and 24b and the negative pressure generating pump 25 are the same as the configurations of the ink flow paths in the conventional inkjet recording apparatus shown in FIG. 8, and thus detailed description thereof will be omitted.

FIG. 4 is a cross sectional view of C- of the joint shown in FIG.
It is sectional drawing in the C line. As shown in FIG. 4, the joint 16 has a hollow portion 16a and connection ports 16b, 16c, 16d communicating with the hollow portion 16a. Connection port 1
The first connection tube 14 is connected to 6b, and the connection port 1
The second connection tube 15 is connected to 6c. Further, a negative pressure tube 17 is connected to the connection port 16d. Therefore, the tubes 14, 15, 17 are communicated with each other through the hollow portion 16a.

The sub-tanks 11a, 1 in this embodiment
Ink replenishment to 1b is also performed in the same manner as in the conventional inkjet recording apparatus described with reference to FIG. That is,
After closing the predetermined flow path opening valve and the atmosphere opening valve, the negative pressure generating pump 25 is driven to drive the sub tanks 11a and 11b.
By sucking the air in the sub-tanks 11a, 1
Ink is replenished in the tank 1b from the main tanks 10a and 10b.

At this time, if extra ink is supplied to the sub-tanks 11a and 11b due to some trouble, the ink discharged from the sub-tank 11a and the ink discharged from the sub-tank 11b are jointed with each other.
Are mixed in the hollow portion 16a. However, in this embodiment, since the joint 16 is installed at a position lower than the sub tanks 11a and 11b, the negative pressure generating pump 25 is stopped, the negative pressure in the negative pressure tube 17 disappears, and the inside of the negative pressure tube 17 is lost. Even when the atmospheric pressure of the sub-tank becomes equal to the atmospheric pressure, the ink mixed in the hollow portion 16a of the joint 16 is connected to both the sub-tanks 11a and 11b connected to the joint 16.
Do not regurgitate inside.

Therefore, the ink sent from the sub-tanks 11a and 11b to the recording head 2 is always a predetermined color, and a so-called "color mixture" occurs in which an image different from the image to be recorded is formed. Can be eliminated.

In this embodiment, one negative pressure generating pump 25 is used to supply ink to the two sub tanks 11a and 11b. However, one negative pressure generating pump is used to supply two inks. The ink may be supplied to the above plurality of sub tanks. Further, a plurality of sub-tanks connected to each recording head, a negative pressure generating pump, and a plurality of units each including a negative pressure tube connected to each sub-tank via a plurality of connecting tubes are provided. In this case, the present invention can be effectively utilized.

Here, the first connecting tube 14 and the second connecting tube 14
A modified example of the connection structure between the connection tube 15 and the negative pressure tube 17 will be described with reference to FIG.

FIG. 5 is a sectional view showing a modification of the connection structure of the first connecting tube, the second connecting tube and the negative pressure tube shown in FIG. 4 and the like. As shown in FIG. 5, in this modification, the first connection tube 14, the second connection tube 15, and the negative pressure tube 17 are connected to each other by the joint portion 2
Directly connected at 6. As described above, the tubes 14, 15, and 17 may be directly connected to each other without using the joint 16 having the hollow portion (see FIG. 4 and the like).

[0047]

As described above, the ink jet recording apparatus of the present invention has a negative pressure tube provided with one negative pressure generating means for making a negative pressure in each sub tank, and each sub tank. Since the connection part with the connected multiple connection tubes is arranged at a position lower than each sub tank,
It is possible to prevent the ink mixed at the connection part from flowing back to each sub-tank, and as a result, so-called "color mixing".
Can be prevented.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of an inkjet recording apparatus of the present invention.

FIG. 2 is a front view of the inkjet recording apparatus shown in FIG.

FIG. 3 is a diagram showing ink flow paths in the inkjet recording apparatus shown in FIGS. 1 and 2.

4 is a cross-sectional view of the joint and the like shown in FIG. 3 taken along the line C-C.

FIG. 5 is a cross-sectional view showing a modified example of the connection structure of the first connection tube, the second connection tube, and the negative pressure tube shown in FIG. 4 and the like.

FIG. 6 is a plan view showing a conventional inkjet recording device.

7 is a front view of the conventional inkjet recording apparatus shown in FIG.

8 is a diagram showing ink flow paths in the conventional inkjet recording apparatus shown in FIGS. 6 and 7. FIG.

9 is a cross-sectional view taken along line BB of the joint and the like shown in FIG.

[Explanation of symbols]

1 Inkjet recording device 2 recording head 3 carriage 4 Recording medium 5 Timing belt 6 Carriage drive motor 6a pulley 7 Sub-scanning roller 8 main board 9 Flexible cable 10 main tank 11 sub tank 12 caterpillar 13 Tank tube 14 First connection tube 15 Second connection tube 16 joints 17 Negative pressure tube 18 head recovery unit 19 head tube 20 Waste ink tank 21 Liquid level sensor 21a, 21b electrodes 22a, 22b Flow path open valve 23a, 23b Flow path open valve 24a, 24b atmosphere release valve 25 Negative pressure generation pump 26 Joint section

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B41J 2/175

Claims (5)

(57) [Claims] 1. A plurality of recording heads that eject ink from nozzles to perform recording on a recording medium, and ink that is respectively connected to the recording heads and that is supplied from an ink supply source to the recording heads. A plurality of sub tanks to hold, and connection tubes respectively connected to the sub tanks
And a negative pressure generating means for making a negative pressure in each of the sub tanks.
A negative pressure tube connected to the plurality of connection tubes and the negative pressure tube.
And a connecting portion for allowing a plurality of the supports to be provided by using one negative pressure generating means.
With an inkjet recording device that supplies ink to the tank
And the connection part is located at a position lower than the sub tanks.
Inkjet recording device characterized by being 2. The negative pressure generating means is driven for a fixed time.
Claimed, configured to automatically stop after
1. The inkjet recording device according to 1. 3. A plurality of the connection tubes and the negative pressure tu
Over Bed and are connected in a state of being communicated with each other via a joint means having a hollow portion, claim 1 or 2
The inkjet recording device according to item 1. 4. A plurality of the connection tubes and the negative pressure tu
Over Bed and is directly connected in a state of communicating with each other, the ink jet recording apparatus according to claim 1 or 2. 5. A plurality of units each including a plurality of the sub-tanks connected to each of the recording heads and a negative pressure tube connected to each of the sub-tanks via a plurality of the connection tubes are provided. From claim 1
5. The inkjet recording device according to any one of items 4 to 4 .