JP2009248412A - Inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method whereby an ink refilling performance to a printing head is improved and a waste ink amount discharged during cleaning is reduced. <P>SOLUTION: The inkjet recorder has a supply filter 121 which passes ink supplied to the printing head 101, a first channel 115 connected to one surface of the supply filter and connecting with a pump 112, a second channel 111 connected to one surface of the supply filter and connecting with an ink tank 110, a third channel 122 connecting the pump and a head discharge opening while bypassing the supply filter, a fourth channel 123 connected to the other surface of the supply filter and connecting with a head supply port, and valves 114 and 119 arranged in the first channel and the third channel. The ink in the printing head is prevented from flowing at the time of one ink flowing of the pump. The ink in the printing head is permitted to flow at the time of the other ink flowing of the pump. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ink supply device in an ink jet recording apparatus.

  FIG. 4 employs a long line head (hereinafter simply referred to as a print head) having a printable width of 2 inches, and ink discharge nozzles for performing printing in the print head, nozzle liquid chambers, and ink flow connected to the nozzle liquid chambers. It is the schematic showing the structure of the ink supply system in the inkjet recording device which has a path. This configuration is disclosed in Patent Document 1 and was devised in order to reduce waste liquid generated when air bubbles staying in a flow path are removed.

  However, FIG. 4 schematically shows one station. When a plurality of print heads are provided, similar ink flow paths are arranged in parallel corresponding to each print head. The ink supply device according to FIG. 4 includes two pumps, a pressurizing pump 409 for sending ink and a suction pump 405 for sucking waste ink, and both pumps can send ink only in the directions indicated by A and B. Yes, the ink flow is maintained when not driven.

  Here, the operation of the ink supply device in the cleaning of the print head 401 will be described. By driving the pressure pump 409 with the pressure valve 412 opened, the ink is pumped in the order of the ink tank 407, the tube 408, the pressure pump 409, the tube 410, and the print head 401. It returns to the ink tank 407 again through the tube 411, the pressurizing valve 412, and the tube 413.

  Ink pumped from the tube 410 flows into the IN-side filter liquid chamber 414, and most or all of the ink flows upward along the head filter 415 and flows out to the tube 411. Therefore, the amount of waste liquid that flows into the nozzle liquid chamber 402 and is discharged to the outside from the ink discharge nozzle 403 is small or zero.

Here, the ink flow path in the print head will be described in detail with reference to FIG.
In the head filter 415, the connection position of the OUT side joint 501 is above the IN side filter liquid chamber 414 provided on the surface of the head filter 415, and the connection position of the IN side joint 502 is below the connection position of the OUT side joint 501. The removal effect is enhanced by utilizing the buoyancy of bubbles during ink circulation cleaning. In addition, a flow path 504 that connects the OUT-side filter liquid chamber 503 and the nozzle liquid chamber 402 is connected upward to the OUT-side filter liquid chamber 503 in order to prevent the accumulation of unnecessary bubbles.

In addition, the circulation of the flow path to the head filter 415 and the ink discharge nozzle 403 is not performed when the ink circulation is recovered, but bubbles generated between the flow paths flow into the nozzle liquid chamber 402 along with the printing, but the printing is not performed. Before the amount of influence accumulates, it is removed by pressure cleaning, which will be described later.
Hereinafter, another operation outline will be described with reference to FIG.

  Ink used for printing or the like is directly supplied from an ink tank 407 set by the user. The ink tank 407 stores ink in a casing member that is an inelastic body, and normally has a blocking structure with respect to the outside. When the ink tank 407 is attached to the apparatus, an ink flow path is formed between the inside of the ink tank 407 and the tubes 408 and 413 by a configuration not shown, and the atmosphere provided in the ink tank 407 is opened to the atmosphere. The valve is opened, and an air flow path is formed between the inside and outside of the ink tank 407.

  Ink pressure cleaning performed to remove the ink discharge nozzle 403 and bubbles, foreign matters, and the like around the ink discharge nozzle 403 is in a state where the pressure valve 412 is closed and the pressure pump 409 is driven to ink the ink. Ink is pumped in order to the tank 407, the pressure pump 409, and the print head 401, the ink is discharged from the ink discharge nozzle 403, and air bubbles in the nozzle liquid chamber 402 and the ink discharge nozzle 403 or attached dust are washed away. .

  When performing printing, the pressurizing valve 412 is opened, and ink is supplied to the print head 401 mainly by the action of capillary action by the ink discharge nozzles 403 from both the tubes 410 and 411, and the head filter 415. While being filtered, the ink flows into the print head 401 and is used for printing.

JP 2004-351541 A

  In the conventional configuration as described above, the flow path 504 for supplying the ink discharge nozzle 403 of the print head is configured in one direction and with a small cross section. This is because, when the above-described pressure cleaning is performed, if the cross section of the flow path becomes large, it is difficult to apply pressure to the foam in the flow path, and it is difficult to discharge the foam. In recent years, a further increase in printing speed and a high duty image have been demanded. In this configuration, there is a limit to ink supply (refill) to the print head.

  Further, it is necessary to sufficiently remove bubbles for further improvement in reliability. However, if an attempt is made to respond by increasing the ink flow rate during pressure cleaning, the amount of waste liquid naturally increases. Further, if the flow path cross section is enlarged in order to improve the ink supply to the print head, a larger amount of ink is discharged during pressure cleaning.

  Accordingly, the problem to be solved by the present invention is to improve the ink supply property to the print head and reduce the amount of waste liquid during pressure cleaning.

In order to solve the above problems, the present invention provides a print head having a nozzle for ejecting ink, the print head holding an ink liquid chamber capable of holding a large amount of ink, and supplying ink to the ink liquid chamber. An ink supply port, an ink discharge port for discharging ink from the ink liquid chamber, and a pump for supplying ink to the print head, and an ink tank which is a container for storing ink In the device
A supply filter that transmits ink to be supplied to the print head; a first flow path that is connected to one surface of the supply filter and that is connected to the pump; and is connected to one surface of the supply filter; A second flow path connected to the ink tank, a third flow path connecting the pump and the head discharge port while bypassing the supply filter, and the other surface of the supply filter, and the head A fourth flow path connected to the supply port, and a valve disposed in the first flow path and the third flow path,
The ink in the print head does not flow when one of the pumps flows, and the ink in the print head flows when the other ink flows in the pump.

  By using the above configuration, it is possible to improve the ink supply (refill) property to the print head and reduce the amount of waste liquid during pressure cleaning.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.
[First embodiment]
FIG. 1 is a schematic view showing an ink flow path of an ink supply apparatus according to the present invention.
However, FIG. 1 schematically shows one station. When a plurality of print heads are provided, similar ink flow paths are arranged in parallel corresponding to each print head.
In this configuration, there are roughly two ink flow path systems, which are first divided into a supply flow path system that supplies ink to the print head 101 and a waste liquid flow path system that processes ink discharged from the print head 101.

First, the configuration of the supply channel system will be described. A print head 101 that performs printing by discharging ink, and a head supply tube 123 on the ink supply side and a head discharge tube 122 on the ink discharge side are connected to the print head 101. A filter liquid chamber 120 having a filter 121 is connected to the head supply tube 123, and ink is supplied to the opposite surface of the filter liquid chamber 120 from the filter supply tube 115 that supplies ink to the filter liquid chamber 120 and the filter liquid chamber 120. A filter discharge tube 116 for discharging is connected. The filter discharge tube 122 is provided at a high position with respect to the filter supply tube 123, and has a positional relationship in which bubbles in the flow path easily pass. The filter 121 is a filtration filter made of metal fibers or the like, and the flow path resistance when the liquid passes through the filter 121 is set lower than the flow path resistance when the liquid passes through the ink discharge nozzle 103 described later. Further, the material of the filter 121 may be a material using resin or fiber other than metal.
A supply valve 114 is connected to the filter supply tube, and the tip thereof is connected to the junction tube 113. The filter discharge tube is connected to the on-off valve 117 and further to the ink tank 110. In the present embodiment, the supply valve 114 and the discharge valve 119 described later use one-way valves, but electromagnetic or pressure bidirectional valves may be used. The ink tank 110 is provided at a low position with respect to the nozzle face 104 of the print head 101. This creates a state in which the negative pressure due to the water head difference is applied to the print head 101 and ink is held on the nozzle face 104.

  In an ink jet printer, it is necessary to hold ink in an ink discharge nozzle that discharges ink in order to perform printing. In this embodiment, as a means for this, a water head difference method or an ink tank based on a height difference between the print head 101 and the ink tank 110 is used. A negative pressure is applied to 110 directly or indirectly. For example, the negative pressure generated in the bag when the bag is expanded with a spring, etc., the negative pressure generated by impregnating the absorber with ink, or the negative pressure generated by mechanical means such as a compressor, pump, fan, etc. Thus, the ink may be held by applying a negative pressure to the print head 101.

  A discharge valve 119 is connected to the head discharge tube 122 and further connected to the junction tube 113. After that, the supply pump 112 that supplies ink to the print head and the supply pump 112 can send ink in both directions (A and B directions in the figure).

  Next, the configuration of the waste liquid channel system will be described. A recovery rod 107 that receives ink discharged from the nozzle face 104 of the print head 101, a waste ink pump 108 that sucks the waste ink received by the recovery rod 107, and the waste ink is finally disposed at the end of the waste ink pump 108. The waste ink tank 109 is held and accumulated in

  The print head 101 is a print head that discharges by an electrothermal conversion element provided in a plurality of ink discharge nozzles 103. However, in the discharge method, the present invention is applied even if a piezoelectric element or a vibration element is used. It is possible to do. Each ink discharge nozzle 103 is arranged in series with the nozzle face surface, and the nozzle face surface 104 has smoothness to improve the adhesion with the recovery rod 107.

  A nozzle liquid chamber 102 is connected to each ink discharge nozzle 103. The nozzle liquid chamber 102 is provided in the upper part of the ink discharge nozzle 103, and raises the bubble generated by the ink discharge nozzle by buoyancy. The upper wall surface of the nozzle liquid chamber 102 is inclined.

  A filter for filtering ink is provided in the vicinity of the upper wall surface of the nozzle liquid chamber, an inflow filter 105 provided at a portion where the ink flows into the print head 101, and a discharge filter provided on the side from which the ink is discharged from the print head 101. The exhaust filter 106 is provided at a higher position than the inflow filter 105. This is to facilitate the collection of bubbles when the bubbles are discharged. Further, a head supply tube 123 is connected to the inflow filter 105, and a head discharge tube 122 is connected to the discharge filter 106.

Each of the ink filtration filters is made of knitted metal fibers or the like, but may be made of resin or fiber, and the filter density and area of each of the inflow filter 105 and the exhaust filter 106 may be different. It is. For example, the inflow filter 105 uses a fine 5 μm hole filter so that dust or the like is not mixed with the inflow of ink, and the discharge filter 106 only discharges bubbles, so that a nozzle with a coarse 20 μm hole can be used properly. Since the bubbles in the liquid chamber 102 are easy to escape from the discharge filter 106 and the ink does not flow in reverse, it is possible to use such as preventing inflow of dust from the discharge filter 106 side.
(Ink supply operation)
The operation of the ink supply apparatus according to the present invention will be described.
First, FIG. 2 shows a recovery operation (circulation cleaning) for removing bubbles other than the print head 101 in order to remove bubbles in the ink flow path. With the on-off valve 117 opened, the supply pump 112 is driven in the A direction. Ink is pumped in the order of the ink tank 110, the tube 111, the supply pump 112, the confluence tube 113, the supply valve 114, the filter supply tube 115, and the filter liquid chamber 120, and further the filter discharge tube 116, The ink is returned to the ink tank 110 again through the on-off valve 117 and the tube 118.

  The ink pumped from the filter supply tube 115 flows into the filter liquid chamber 120, and all the ink flows upward along the filter 121 and flows out to the filter discharge tube 116 due to the flow path resistance of the filter 121. During the circulation cleaning, the pressure by the supply pump 112 is equal to or less than the flow path resistance of the filter 121, the ink cannot pass through the filter 121, the ink continues to flow along the surface of the filter 121, and the ink passes through the filter discharge tube. To 116. That is, ink does not flow out to the print head 101, and in this state, there is no waste amount of ink. This operation forms a preparation state before the print head 101 is recovered.

  Second, a recovery operation (pressure cleaning) for filling the print head 101 with ink is shown in FIG. In the pressure cleaning, the supply pump 112 is driven in the A direction with the on-off valve 117 being shielded. Since the ink does not flow into the filter discharge tube 116 by the on-off valve 117, the pressure applied to the ink rises and can pass through the filter 121. The ink that has passed through the filter 112 flows into the print head 101.

  Incoming ink passes through the inflow filter 105 and then flows into the nozzle liquid chamber 102 in the print head 101. The nozzle liquid chamber 102 is characterized by having a larger ink storage capacity than the conventional nozzle liquid chamber. The ink that has flowed in tends to further flow from the discharge filter 106 to the head discharge tube 122. However, there is a junction tube 113 ahead, and since the ink flow (P in the figure) is generated by the supply pump 112, the ink cannot proceed further. Therefore, only the ink discharge nozzle 103 is used as a pressure escape area, and the ink discharge nozzle 103 and the nozzle liquid chamber 102 are filled with ink. Further, after filling, the ink is discharged from the nozzle 103, received by the recovery rod 107, and accumulated in the waste ink tank 109 by the waste ink pump 108.

  In the print head of this configuration, as shown in FIG. 4, the discharge filter 106 is disposed above the inflow filter 105, and the inclination of the upper wall surface of the nozzle liquid chamber 102 rises from the inflow filter 105 toward the discharge filter 106. Inclined to do. With this configuration, the bubbles 201 in the print head 101 are accumulated around the discharge filter 106.

  Third, a recovery operation (bubble removal cleaning) for removing bubbles in the print head 101 is shown in FIG. At the time of bubble cleaning, the on-off valve 117 is opened and ink is supplied from the ink tank 110. Subsequently, the supply pump 112 is driven in the direction B opposite to the A direction. The ink is returned to the discharge filter 106, the head discharge tube 122, the discharge valve 119, the merging tube 113, the supply pump 112, the tube 111, and the ink tank 110. Since the on-off valve 117 is open at this time, the flow path resistance on the filter discharge tube 116 side is small, and the flow path resistance on the filter supply tube 115 side affected by the action of the supply valve 114 is large, so the filter supply tube 115 side This ink does not flow, and only the ink on the filter discharge tube 116 side flows.

  The ink flowing from the filter discharge tube 116 flows into the print head 101 from the head supply tube 123 and flows out of the head discharge tube 122. As described above, since the bubbles are accumulated around the discharge filter 106, the bubbles can be discharged by a small amount of ink flow. The pressure that the print head 101 receives from the supply pump 112 is a negative pressure due to suction. However, since the flow path resistance of the filter 121 is smaller than the flow path resistance of the ink discharge nozzle 103, air is sucked from the ink discharge nozzle 103. The ink is discharged only from the head discharge tube 122. At this time, no ink is discharged from the print head 101 to the recovery rod 107.

  The flow rate set in the above-described cleaning is set to a value necessary for causing the bubbles to flow and return to the ink tank 110. However, since the bubbles 201 are gathered around the discharge filter 106, a large amount of ink is conventionally used. It is not necessary to make it flow, and a flow rate that can mainly flow only bubbles is sufficient. In this embodiment, about 1 to 3 CC flows. Conventionally, the flow of ink is 10 to 30 CC, so that the ink flow rate is much smaller than that of the conventional one, and the bubbles can be easily removed.

  In addition, the cleaning of bubbles generated during printing or standby of the apparatus may be performed in the same manner as the above-described bubble removal cleaning. Since the nozzle liquid chamber 122 provided in the print head 101 is configured so as to be able to store a large amount of ink, it is very advantageous for ink supply (refill) to the ink discharge nozzle 103 during printing. In particular, even when bubbles are generated in the head, the generated bubbles move to the discharge filter 106 by buoyancy, so that the possibility of causing printing defects due to the bubbles entering the ink discharge nozzle 103 is reduced.

  During printing, ink is supplied from the head supply tube 122 and the inflow filter 105. When ink is ejected from the ink ejection nozzle 103, the inside of the ink ejection nozzle 103 becomes negative pressure, and the ink is refilled by the negative pressure. By the way, the ink does not flow into the discharge filter 106 from the outside. This is because the discharge valve 119 can only flow in a certain direction. Therefore, the discharge filter 106 may be coarser than the inflow filter 105 (20 μm in this embodiment), and may be of a size that can prevent dust mixed during the manufacturing process and distribution of the print head 101.

The supply pump 112 needs to generate forward and reverse ink flows at the installation portion in the present embodiment, and uses the most efficient tube pump.
[Second Embodiment]

A second embodiment of the present invention is shown in FIG. The basic configuration is the same as that of the first embodiment, and the components to which no illustration is given are the same as those of the first embodiment.
A switching member 303 for switching the ink flow path is provided at a branch point where the merging tube 306 divides into the filter supply tube 307 and the head discharge tube 312. The switching member 303 is configured to alternately shield the flow path on the filter supply tube 307 side and the flow path on the head discharge tube 312 side. The supply pump 112 is rotatable in the A direction and the B direction, and the shielding position of the switching member 303 is changed depending on the rotation direction.
During circulation cleaning, the switching member 303 is configured to shield the head discharge tube 312. Subsequently, the supply pump 112 is driven in the A direction with the on-off valve 117 being opened. Ink is pumped in the order of the ink tank 110, the tube 111, the supply pump 112, the confluence tube 306, the filter supply tube 307, and the filter liquid chamber 120, and the filter discharge tube 116, the on-off valve 117, The tube 118 is returned to the ink tank 110 again.

  Ink fed by pressure from the filter supply tube 307 flows into the filter liquid chamber 120, and all ink flows upward along the filter 121 and flows out to the filter discharge tube 116 due to the flow path resistance of the filter 121. During the circulation cleaning, the pressure by the supply pump 112 is equal to or less than the flow path resistance of the filter 121, the ink cannot pass through the filter 121, the ink continues to flow along the surface of the filter 121, and the ink passes through the filter discharge tube. To 116. That is, ink does not flow out to the print head 101, and in this state, there is no waste amount of ink. This operation forms a preparation state before the print head 101 is recovered.

  During pressure cleaning, the supply pump 112 is driven in the A direction with the on-off valve 117 being shielded. Since the ink does not flow into the filter discharge tube 116 by the on-off valve 117, the pressure applied to the ink rises and can pass through the filter 121. The ink that has passed through the filter 112 flows into the print head 101.

Incoming ink passes through the inflow filter 105 and then flows into the nozzle liquid chamber 102 in the print head 101. The nozzle liquid chamber 102 is characterized by having a larger ink storage capacity than the conventional nozzle liquid chamber. The ink that has flowed in tends to further flow from the discharge filter 106 to the head discharge tube 122. There is a switching valve 303, and the ink cannot proceed any further. Therefore, only the ink discharge nozzle 103 is used as a pressure escape area, and the ink discharge nozzle 103 and the nozzle liquid chamber 102 are filled with ink. Further, after filling, the ink is discharged from the nozzle 103, received by the recovery rod 107, and accumulated in the waste ink tank 109 by the waste ink pump 108.
At the time of bubble cleaning, the on-off valve 117 is opened and ink is supplied from the ink tank 110. Subsequently, the supply pump 112 is driven in the direction B opposite to the A direction. The ink is returned to the discharge filter 106, the head discharge tube 312, the switching valve 303, the merging tube 306, the supply pump 112, the tube 111, and the ink tank 110. Since the on-off valve 117 is open at this time, the flow path resistance on the filter discharge tube 116 side is small, and the flow path resistance on the filter supply tube 115 side affected by the action of the supply valve 114 is large, so the filter supply tube 115 side This ink does not flow, and only the ink on the filter discharge tube 116 side flows.

The ink flowing from the filter discharge tube 116 flows into the print head 101 from the head supply tube 123 and flows out from the head discharge tube 312. As described above, since the bubbles are accumulated around the discharge filter 106, the bubbles can be discharged by a small amount of ink flow. The pressure that the print head 101 receives from the supply pump 112 is a negative pressure due to suction. However, since the flow path resistance of the filter 121 is smaller than the flow path resistance of the ink discharge nozzle 103, air is sucked from the ink discharge nozzle 103. The ink is discharged only from the head discharge tube 312. At this time, no ink is discharged from the print head 101 to the recovery rod 107.

Ink flow path diagram representing the first embodiment The figure which shows the flow of the ink showing a 1st Example. The figure which shows the flow of the ink showing a 1st Example. Ink flow path in the print head in the first embodiment The figure which shows the flow of the ink showing a 1st Example. Ink flow path diagram representing the second embodiment Ink flow chart with conventional configuration Ink flow path inside the print head with the conventional configuration

Explanation of symbols

DESCRIPTION OF SYMBOLS 101: Print head 102: Nozzle liquid chamber 103: Ink discharge nozzle 104: Nozzle face surface 105: Inflow filter 106: Discharge filter 107: Recovery trap 108: Waste ink pump 109: Waste ink tank 110: Ink tank 112: Supply pump 113 : Confluence tube 114: Supply valve 115: Filter supply tube 116: Filter discharge tube 117: On-off valve 119: Discharge valve 120: Filter liquid chamber 121: Filter 122: Head discharge tube 123: Head supply tube 201: Bubble 303: Switching member

Claims (7)

A print head including a nozzle for ejecting ink, the print head holding an ink liquid chamber capable of holding a large amount of ink, an ink supply port for supplying ink to the ink liquid chamber, and the ink liquid chamber In an ink jet recording apparatus comprising: an ink discharge port for discharging ink; a pump capable of forward / reverse supplying ink to the print head; and an ink tank which is a container for storing ink.
A supply filter that transmits ink to be supplied to the print head; a first flow path that is connected to one surface of the supply filter and that is connected to the pump; and is connected to one surface of the supply filter; A second flow path connected to the ink tank; a third flow path connecting the pump and the discharge port while bypassing the supply filter; and the other surface of the supply filter; and the ink A fourth flow path connected to the supply port, and a valve disposed in the first flow path and the third flow path,
An ink jet recording apparatus, wherein ink in the print head does not flow when one ink of the pump flows, and ink in the print head flows when the other ink of the pump flows.   The inkjet recording apparatus according to claim 1, wherein an opening / closing valve that can be opened and closed is provided in the second flow path.   The inkjet recording apparatus according to claim 1, wherein the valve is a one-way valve provided in each of the first flow path and the third flow path.   The one-way valve provided in the first flow path is a supply valve that can only supply ink to the print head, and the one-way valve provided in the second flow path can discharge only ink from the print head. 4. The ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus is a valve.   The inkjet according to claim 1, wherein an ink filtration filter is connected to each of the ink supply port and the discharge port, and the ink filtration filter is disposed at a position having a different height in the ink liquid chamber. Recording device.   The ink jet recording apparatus according to claim 2, wherein the ink filtration filter has a higher position on the discharge port side than on the supply port side.   4. The ink jet recording apparatus according to claim 2, wherein the ink filtration filter has a coarser mesh on the discharge port side than on the supply port side.

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