JP2014080008A - Printer and method of supplying liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printer equipped with a liquid supply mechanism which has a simple configuration and is capable of modifying the pressure for pumping a cleaning solution and a method of supplying a liquid.SOLUTION: A liquid supply mechanism 20 supplying a cleaning solution to cleaning heads 43 comprises an air supply pipe 53 supplying compressed air from an air supply source 51 to a cleaning solution tank 73, a supply pipe 55 supplying the cleaning solution from the cleaning solution tank 73 to manifold 74 and a supply pipe 56 branched from the manifold 74 and supplying the cleaning solution to each cleaning head 43. The cleaning solution tank 73 has an air-tight structure and is connected to the air supply pipe 53. In the air supply pipe 53, three discharge tubes 54 communicating with the atmosphere are arranged in a branched form to discharge the compressed air out of the printer so as to adjust the pressure for pumping the cleaning solution. In each of the discharge tubes 54, flow rate adjustment valves 71a, 71b and 71c and opening/closing valves 72a, 72b and 72c are interposed respectively.

Description

  The present invention relates to a printing apparatus including a liquid supply mechanism that supplies a cleaning liquid to an ink ejection head in a printing apparatus, and a liquid supply method.

  In a printing apparatus that performs printing by relatively moving an inkjet head having a plurality of nozzles for ejecting ink and a recording medium, the ink adhering matter or dust covers the nozzle tip and is called nozzle missing. Printing defects may occur. In order to prevent such printing defects, such a printing apparatus is provided with a cleaning mechanism that cleans the nozzles of the inkjet head and its peripheral portion.

  A cleaning mechanism for an ink jet printer described in Patent Document 1 includes a cleaning device that ejects cleaning liquid onto the lower surface of a recording head in which one ink jet head is arranged for each ink color, and dirt and cleaning liquid adhering to the lower surface of the recording head. It is equipped with a blade to wipe off. The cleaning liquid is ejected from the wipe nozzle that supplies the cleaning liquid to the lower surface of the recording head (the surface facing the recording medium) by such a cleaning apparatus. The operation of the pump and the compressed air flow by flowing compressed air into the cleaning liquid tank It is executed by.

  In addition, as an inkjet printing apparatus for performing printing of a large number of copies at a high speed, a plurality of inkjet heads are used in order to obtain a discharge width substantially the same as the width in the main scanning direction orthogonal to the conveyance direction (sub-scanning direction) of the recording medium. What is called a one-pass inkjet printing apparatus that includes recording heads arranged at predetermined intervals in the main scanning direction and the sub-scanning direction, and performs recording by ejecting ink on a transported recording medium as necessary. It is known (see Patent Document 2).

  In the cleaning of the recording head in such a one-pass type ink jet printing apparatus, the cleaning operation is performed when all the ink jet heads are cleaned at once or only the ink jet head having clogged nozzles is cleaned. There are variations.

JP 2005-144737 A Japanese Patent Laid-Open No. 2007-261088

  As a mode that can flexibly cope with variations in the cleaning operation of the ink jet head, wipe nozzles that inject cleaning liquid onto the lower surface of the ink jet head are provided by the number of columns in the sub scanning direction of the ink jet head arranged in the main scanning direction and the sub scanning direction. There is an embodiment in which the cleaning liquid is disposed and supplied to each wipe nozzle by air pressure feeding. When such an aspect is employed, the number of wipe nozzles from which the cleaning liquid is ejected among the plurality of wipe nozzles that eject the cleaning liquid to the lower surface of the inkjet head varies depending on the number of inkjet heads to be cleaned. In addition, when supplying cleaning liquid to each wipe nozzle by air pressure feeding, air at a constant pressure is often taken into the cleaning liquid pumping path from the air supply pipe of the factory equipment, and it is difficult to variably adjust the original pressure of the air supply source. is there. For this reason, as the number of wipe nozzles that discharge the cleaning liquid decreases, the discharge pressure of the cleaning liquid per wipe nozzle increases. As a result, a difference occurs in the flow rate of the cleaning liquid supplied to the lower surface of the inkjet head in accordance with the number of wipe nozzles that discharge the cleaning liquid, resulting in a difference in the cleaning effect.

  The present invention has been made to solve the above problems, and provides a printing apparatus and a liquid supply method including a liquid supply mechanism capable of changing the pressure for pumping the cleaning liquid with a simple configuration. Objective.

  The invention according to claim 1 is a printing apparatus including a liquid supply mechanism that supplies a cleaning liquid for cleaning an ink discharge head to the discharge head. The liquid supply mechanism includes a storage unit that stores the cleaning liquid, and the storage unit. A liquid supply pipe for supplying a liquid to the cleaning unit by the action of compressed air from a section, a cleaning unit provided with a wipe nozzle for ejecting a cleaning liquid toward the discharge head, and a compression from an air supply source to the storage section An air supply pipe through which air flows, a discharge pipe branched from the air supply pipe and communicating with the atmosphere, an on-off valve inserted in the exhaust pipe, and an on-off valve inserted in the exhaust pipe to open the on-off valve The flow rate adjusting valve for adjusting the flow rate of the compressed air discharged from the discharge pipe to the atmosphere at the time, and the open / close state of the on / off valve to control the compressed air at the flow rate set in the flow rate adjusting valve. And atmospheric emissions, characterized in that and a control means for adjusting the flow rate of the compressed air to flow into the reservoir.

  According to a second aspect of the present invention, in the first aspect of the present invention, the cleaning unit includes a plurality of wipe nozzles branched from a liquid supply pipe that supplies a cleaning liquid, the wipe nozzle, and a branched liquid supply pipe. A liquid supply opening / closing valve interposed between each of the plurality of wipe nozzles is disposed, and the control means controls the liquid supply opening / closing valve according to the number of wipe nozzles that eject the cleaning liquid during the cleaning operation. The flow rate of the compressed air that flows into the reservoir is adjusted by controlling the number of opening and the number of opening the opening / closing valve inserted in each of the plurality of discharge pipes.

  According to a third aspect of the present invention, in the second aspect of the present invention, the flow rate adjusting valves inserted into the plurality of discharge pipes are set to flow rates different from each other, and the control means includes the plurality of flow rate control valves. The flow rate of the compressed air flowing into the storage portion is adjusted in multiple stages by the combination of the open / close state of the open / close valve inserted in the discharge pipe.

  According to a fourth aspect of the present invention, there is provided a liquid for supplying a cleaning liquid to a cleaning unit for cleaning a discharge head in which a nozzle for discharging a liquid is formed, by a pressure of compressed air flowing from an air supply source into a cleaning liquid reservoir. In the supply method, the flow rate of a flow rate adjusting valve inserted into an exhaust pipe communicating with the atmosphere branched from an air supply pipe that supplies compressed air to the reservoir is set, and inserted into the exhaust pipe. An adjustment step of adjusting the flow rate of the compressed air that flows into the storage unit by discharging the compressed air to the atmosphere at a flow rate set in the flow rate adjustment valve by opening and closing the on-off valve; .

  According to a fifth aspect of the present invention, in the fourth aspect of the invention, the cleaning liquid is ejected during the cleaning operation among the plurality of wipe nozzles that eject the cleaning liquid toward the ejection head disposed in the cleaning unit. According to the number of wipe nozzles and the flow rate setting of the flow rate adjusting valve respectively inserted into a plurality of discharge pipes communicating with the atmosphere branched from an air supply pipe that supplies compressed air to the storage section, A step of determining a combination of open / close states of the open / close valves respectively inserted into the plurality of discharge pipes for applying a predetermined liquid supply pressure corresponding to the number of the open / close valves; The flow rate of the compressed air flowing into the storage part is adjusted by opening and closing the on-off valve based on the combination of the open and closed states.

  According to the first to fifth aspects of the present invention, the flow rate adjusting valve and the on-off valve are disposed in the discharge pipe communicating with the atmosphere branched from the air supply pipe for supplying the compressed air to the cleaning liquid reservoir. Therefore, the open / close control of the open / close valve allows the compressed air at the flow rate set in the flow adjustment valve to be discharged to the atmosphere, and the pressure when pumping the cleaning liquid can be easily changed with a simple configuration. Become.

  According to the second aspect of the invention, among the plurality of wipe nozzles that eject the cleaning liquid toward the ejection head, the number of open / close valves that are opened is changed according to the number of wipe nozzles that eject the cleaning liquid during the cleaning operation. Even if the number of wipe nozzles that eject the cleaning liquid changes, the cleaning effect can be maintained without greatly changing the discharge pressure on the side of the wipe nozzle that ejects the cleaning liquid.

  According to the third and fifth aspects of the present invention, the flow rate adjusting valve and the on / off valve set to different flow rates are inserted in the plurality of discharge pipes, respectively. The amount of compressed air discharged from the air supply pipe can be changed in multiple stages, and the discharge amount from each nozzle can be made constant.

1 is a schematic diagram schematically showing a main part of a printing apparatus according to the present invention. 2 is a perspective view illustrating an outline of the printing unit 1. FIG. 2 is a schematic diagram of a cleaning unit 40. FIG. FIG. 2 is a schematic diagram schematically showing a liquid supply mechanism 20. 2 is a block diagram illustrating a main configuration of a control system of the printing apparatus according to the present invention. FIG. 7 is a table showing the relationship between the flow rate setting of the flow rate adjusting valves 71a, 71b, 71c, the open / close control of the open / close valves 72a, 72b, 72c, and the number of wipe nozzles 41 to which the cleaning liquid should be discharged and the pressure.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram schematically showing a main part of a printing apparatus according to the present invention. FIG. 2 is a perspective view for explaining the outline of the printing unit 1.

  This printing apparatus is an ink jet head which is an ink discharge head for a printing paper 5 which is a long recording medium which is guided by a guide roller 6 and moves in the direction of the arrow shown in FIG. The printing is executed by ejecting ink from No.2. The recording head 10 has a printing unit 1 c for printing on the printing paper 5 with cyan ink, a printing unit 1 m for printing on the printing paper 5 with magenta ink, and a printing paper 5. The printing unit 1 y for printing with yellow ink and the printing unit 1 k for printing with black ink on the printing paper 5 are the movement direction (sub-scanning direction) of the printing paper 5. It has the structure arranged in the direction.

  The printing units 1c, 1m, 1y, and 1k (hereinafter collectively referred to as “printing unit 1”) corresponding to each ink color include a Y direction that is a moving direction of the printing paper 5 and a width of the printing paper 5. A plurality of inkjet heads 2 are arranged at predetermined intervals in the X direction, which is the direction (main scanning direction). These inkjet heads 2 are arranged to penetrate through the inkjet head holding plate 11 and are configured to be able to eject ink from ink ejection nozzles formed on the lower surface of each inkjet head 2.

  The printing unit 1 shown in FIG. 2 has a row in which three inkjet heads 2 are arranged in the X direction arranged on the inkjet head holding plate 11 so that the positional relationship in the Y direction of the inkjet heads 2 is in parallel. doing. By arranging the inkjet heads 2 in parallel in the Y direction in this way, the ink discharge nozzles formed on each inkjet head 2 are arranged without interruption in the width direction of the printing paper 5 for each ink color. ing. In addition, the number of the inkjet heads 2 of the printing unit 1 is not limited to the aspect shown in FIG.

  A cleaning unit 40 is disposed below the printing unit 1, and three cleaning heads 43 are disposed for one printing unit 1. The cleaning head 43 is arranged at a position corresponding to the arrangement of the rows of the inkjet heads 2 held by the inkjet head holding plate 11. In this embodiment, since the printing units 1 for four ink colors are arranged in the Y direction, the cleaning unit 40 has a configuration in which 12 cleaning heads 43 are arranged in the cleaning head holding unit 14. Have The cleaning head holding unit 14 reciprocates in the X direction orthogonal to the moving direction of the printing paper 5 by a driving mechanism (not shown). As the cleaning head holding unit 14 moves, the lower surface of each inkjet head 2 is cleaned.

  FIG. 3 is a schematic diagram of the cleaning unit 40. 3A is a plan view of the cleaning unit 40, and FIG. 3B is a front view showing the cleaning unit 40 together with the inkjet head 2. FIG.

  As shown in FIG. 3A, the cleaning head 43 constituting the cleaning unit 40 includes a wipe nozzle 41 that discharges a cleaning liquid and a wiper blade 42. When the cleaning head holding unit 14 moves, the cleaning liquid is ejected from the wipe nozzle 41 toward the lower surface of the inkjet head 2, and immediately thereafter, the wiper blade 42 wipes the lower surface of the inkjet head 2 to which the cleaning liquid has adhered. As described above, the ejection of the cleaning liquid and the wiping of the cleaning liquid are executed in accordance with the movement of the cleaning head holding unit 14, whereby the lower surface of each inkjet head 2 is cleaned. Further, the wiper blade 42 is configured to be movable up and down, and when passing under the inkjet head 2 that is not a cleaning target, the wiper blade 42 is moved to a position where it does not contact the lower surface of the inkjet head 2 (see FIG. 3 (b)). Thereby, unnecessary friction between the inkjet head 2 and other members between the heads and the wiper blade 42 can be avoided, and the life of the wiper blade 42 can be extended.

  Next, a liquid supply mechanism that supplies the cleaning liquid to the cleaning head 43 in the cleaning unit 40, which is a characteristic part of the present invention, will be described. FIG. 4 is a schematic diagram schematically showing the liquid supply mechanism 20.

  In the printing apparatus according to this embodiment, ink is supplied from the main tank 61 that stores ink of each ink color to each inkjet head 2 via the sub tank 62, and cleaning liquid is supplied from the cleaning liquid tank 73 to each cleaning unit 40. Air pressure is used for supply. Accordingly, the air pressure supply path in this printing apparatus is constituted by an air supply pipe 52 that sends compressed air from the air supply source 51 to each main tank 61 and an air supply pipe 53 that sends compressed air from the air supply source 51 to the cleaning liquid tank 73. It is divided into two routes. As the air supply source 51, an air compressor dedicated to the printing apparatus may be used, or compressed air is introduced into the air pressure supply path of the printing apparatus from a compressed air pipe arranged as factory equipment. It may be.

  The main tank 61 has an airtight structure, and an air supply pipe 52 is connected thereto. A sub tank 62 is disposed between the main tank 61 and the inkjet head 2, and the compressed air is supplied from the air supply pipe 52 to pressurize the main tank 61, so that the ink in the main tank 61 is discharged. The ink is supplied to the sub-tank 62, and this ink is further supplied from the sub-tank 62 to each inkjet head 2.

  The liquid supply mechanism 20 that supplies the cleaning liquid to the cleaning head 43 includes an air supply pipe 53 that supplies compressed air from the air supply source 51 to the cleaning liquid tank 73, a supply pipe 55 that supplies the cleaning liquid from the cleaning liquid tank 73 to the manifold 74, A supply pipe 56 that branches from the manifold 74 and supplies the cleaning liquid to each cleaning head 43 is provided. The cleaning liquid tank 73 has an airtight structure and is connected to the air supply pipe 53. The compressed liquid is introduced from the air supply pipe 53 to pressurize the cleaning liquid tank 73, whereby the cleaning liquid in the cleaning liquid tank 73 is supplied to the manifold 74 via the supply pipe 55 and supplied to the cleaning head 43. ing.

  In order to adjust the pressure when the cleaning liquid is pumped, the air supply pipe 53 is divided into three discharge pipes 54 that communicate with the atmosphere to discharge the compressed air to the outside of the printing apparatus. Flow rate adjusting valves 71a, 71b, 71c and on-off valves 72a, 72b, 72c are inserted in the discharge pipes 54, respectively. Further, twelve on-off valves 75a to 75l are inserted in the supply pipes 56 that branch from the manifold 74 and supply the cleaning liquid to the cleaning heads 43, respectively. The open / close valves 72a, 72b, 72c inserted in the discharge pipes 54 and the open / close valves 75a to 75l inserted in the supply pipes 56 are opened / closed by signals from the control unit 80 described later. Is a solenoid valve to be controlled. The on-off valves 75a to 75l correspond to the liquid supply on-off valves in the present invention.

  FIG. 5 is a block diagram showing the main configuration of the control system of the printing apparatus according to the present invention.

  The control unit 80 includes a CPU, a memory, and peripheral circuits thereof, and includes a print control unit 82 and a cleaning control unit 81 as functional configurations. The print control unit 82 controls the ejection amount and ejection timing of ink from the ink ejection nozzles formed on each inkjet head 2 of the recording head 10.

  The cleaning control unit 81 acquires position information of the inkjet head 2 to be cleaned, generates a control signal for controlling the operation of the moving mechanism 83 of the cleaning head holding unit 14 and the vertical mechanism 84 of the wiper blade 42, and supplies the control signal A control signal for controlling opening and closing of the on-off valves 75a to 75l inserted in the pipe 56 is generated. Further, the cleaning control unit 81 counts the number of wipe nozzles 41 that should discharge the cleaning liquid and the number of wipe nozzles 41 that should discharge the cleaning liquid among the wipe nozzles 41 of the 12 cleaning heads 43, and is inserted into the discharge pipe 54. A control signal for controlling opening / closing of the open / close valves 72a, 72b, 72c is generated.

  Next, in the printing apparatus having the above-described configuration, opening / closing control of the opening / closing valves 72a, 72b, 72c and pressure adjustment in the cleaning liquid tank 73 when cleaning the inkjet head 2 will be described. FIG. 6 is a table showing the relationship between the flow rate setting of the flow rate adjusting valves 71a, 71b, 71c, the open / close control of the open / close valves 72a, 72b, 72c, and the number of wipe nozzles 41 to which the cleaning liquid should be discharged and the pressure.

  In this embodiment, since 12 cleaning heads 43 are arranged corresponding to the number of rows 12 of the inkjet heads 2 in the Y direction, the total number of wipe nozzles 41 is 12. Assuming that the ideal pressure at which the cleaning effect is suitable when the cleaning liquid is discharged from one wipe nozzle 41 is 1, regardless of the number of wipe nozzles 41 that discharge the cleaning liquid, the flow rate of the cleaning liquid discharged from the wipe nozzle 41 ( For example, if the number of wipe nozzles for discharging the cleaning liquid is n = 7, the original pressure of the air supply source 51 is increased seven times, and if the number of wipe nozzles is n = 12, the original amount of discharge liquid per unit time is fixed. It is sufficient to increase the pressure by 12 times. However, when compressed air is introduced into the cleaning liquid supply path from the piping of the factory equipment as the air supply source 51, the original pressure cannot be easily adjusted. Therefore, in the present invention, by adjusting the pressure applied to the cleaning liquid tank 73 without adjusting the original pressure, the cleaning liquid discharged from one wipe nozzle 41 is controlled regardless of the number of wipe nozzles 41 that discharge the cleaning liquid. The flow rate can be kept within a predetermined range without greatly fluctuating.

  First, as described above, in this embodiment, three discharge pipes 54 are branched and arranged in the air supply pipe 53 from the air supply source 51 to the cleaning liquid tank 73, and each of the discharge pipes 54 is arranged. The flow rate adjusting valves 71a, 71b, 71c and the on-off valves 72a, 72b, 72c are inserted in the valve. Then, by opening the on-off valves 72a, 72b, 72c, the compressed air is released to the outside of the printing apparatus at the flow rates set in the flow rate adjusting valves 71a, 71b, 71c, and the remaining compressed air is supplied to the cleaning liquid tank 73. doing. The amount of compressed air that flows into the cleaning liquid tank 73 is adjusted by changing the number of open / close valves that are opened among the open / close valves 72a, 72b, and 72c.

  The flow rate adjusting valves 71a, 71b, 71c are set to predetermined leak rate ratios different from each other. The leakage amount ratio indicates how much of the compressed air supplied from the air supply source 51 to the air supply pipe 53 is discharged out of the printing apparatus. The flow rate adjustment valve 71 a is adjusted in flow rate so that 14% of the compressed air supplied to the air supply pipe 53 is discharged from the discharge pipe 54 when the on-off valve 72 a is opened. The flow rate adjustment valve 71b is adjusted in flow rate so that 25% of the compressed air supplied to the air supply pipe 53 is discharged from the discharge pipe 54 when the on-off valve 72b is opened. The flow rate adjusting valve 71c is adjusted so that 52% of the compressed air supplied to the air supply pipe 53 is discharged from the discharge pipe 54 when the on-off valve 72c is opened. That is, the flow rate adjusting valves 71a, 71b, 71c are set with a leak rate ratio of a = 0.14, b = 0.25, c = 0.52, as shown in the table of FIG. These leak rate ratios are adjusted and fixed in advance to the respective flow rate adjusting valves 71a, 71b, 71c. Further, after this setting, each leakage ratio may be stored and held in the control unit 80.

  Here, since there are three discharge pipes 54 provided with the flow rate adjusting valves 71a, 71b, 71c in which different leakage amount ratios are set, of the compressed air supplied from the air supply pipe 53, the air supply pipe The amount of leakage of compressed air that can be discharged from each of the exhaust pipes 54 through 53 is 1-8 depending on the combination of the open / close valves 72a, 72b, and 72c inserted in the discharge pipes 54, 1 / closed, and 0. It can be switched to 8 stages. Since the total number of wipe nozzles 41 is 12, it is ideal that the amount of leakage of compressed air for supplying the cleaning liquid is switched to 12 steps according to the total number of wipe nozzles 41. However, when the number of wipe nozzles to which the cleaning liquid is to be discharged is 10 and 11, the pressure applied to the cleaning liquid tank 73 remains a change of 11/10 = 1.1 times. For this reason, it may be considered that the flow rate of the cleaning liquid from each wipe nozzle 41 is almost the same in the case where the number of wipe nozzles to which the cleaning liquid is to be discharged is 10 and in the case of 11. Therefore, in this embodiment, even when the number of supply pressure switching is limited by the number of on-off valves or the like that adjust the leakage amount ratio, it is considered whether or not the cleaning liquid can be supplied at substantially the same flow rate even at the same supply pressure. Thus, the number of wipe nozzles n is made to correspond to the number of switching that determines the amount of compressed air leakage. The correspondence between the number n of wipe nozzles that should discharge the cleaning liquid and the amount of compressed air leakage is the pressure ratio [(n + 1) / n] and the leak rate ratio of the flow rate adjusting valves 71a, 71b, 71c can be determined. When the number of wipe nozzles n = 1, it is not necessary to consider the pressure ratio.

  In the example of the table shown in FIG. 6, when the cleaning liquid is ejected from one air nozzle 41 from the air supply source 51, 10.5 is assumed when the ideal pressure per one wipe nozzle that makes the cleaning effect suitable is 1. Double pressure is supplied. The ratio of the ideal pressure and the original pressure here is 1: 10.5. For example, when the cleaning liquid is discharged from four wipe nozzles 41 (number of wipe nozzles n = 4), the combination of the open / close states of the open / close valves 72a, 72b, 72c is the third-stage open / close valve 72a → 1 and open / close valve 72b → 0. , The on-off valve 72c → 1. That is, two of the on-off valves 72a, 72b, and 72c are in the open state, that is, the on-off valve 72a and the on-off valve 72c.

  Open / close valves 72a, 72b, 72c are opened / closed according to the number of wipe nozzles 41 that eject the cleaning liquid during the cleaning operation and the setting of the leakage amount ratio (flow rate setting) of the flow rate adjusting valves 71a, 71b, 71c. An adjustment step for adjusting the flow rate of the compressed air flowing into the cleaning liquid tank 73 is executed by outputting a signal for opening the opening / closing valve 72a and the opening / closing valve 72c from the cleaning control unit 81 through the step of determining the combination of states. The Then, 66% of the original pressure is discharged through the flow rate adjusting valves 71a and 71c, and the remaining 34% is supplied to the cleaning liquid tank 73. The supply pressure to the cleaning liquid tank 73 at this time is 3.6 times the ideal pressure per wipe nozzle (10, 5 × 0.34 = 3.6), and when this is divided by the number of wipe nozzles n = 4, As the pressure per wipe nozzle, a pressure 0.9 times the ideal pressure per wipe nozzle can be secured.

  In the printing apparatus according to the present invention, even if the number of wipe nozzles 41 to which the cleaning liquid is to be discharged fluctuates, the flow rate adjusting valves 71a, 71b, 71c and the open / close valves 72a, 72b, 72c are used to supply the cleaning liquid tank 73. By adjusting the flow rate of the supplied compressed air, the pressure per wipe nozzle is reduced to 0. 0 of the ideal pressure per wipe nozzle as shown in the column “pressure per wipe nozzle” in the table of FIG. It is possible to adjust to a range of 9 to 1.2 times. Note that the numerical values in the columns “Supply pressure” and “Pressure per wipe nozzle” in the table of FIG. 6 are values rounded off to one decimal place.

  In the conventional printing apparatus not configured to change the source pressure, when the number of wipe nozzles 41 to which the cleaning liquid is to be discharged is large, the discharge pressure of the cleaning liquid is 1 when the number of wipe nozzles 41 to which the cleaning liquid is to be discharged is small. / 2 or less, resulting in a problem that the cleaning effect is impaired. However, in the printing apparatus according to the present invention, even if the number of wipe nozzles 41 to which the cleaning liquid is to be discharged varies, the pressure variation per wipe nozzle can be kept within a certain range. Even when cleaning is performed for one unit of the printing unit arranged for each ink color to which the cleaning liquid is to be ejected, or when cleaning is performed for 10 units of the recording head that is to eject the cleaning liquid from the twelve wipe nozzles 41, An equivalent cleaning effect can be obtained. That is, a high cleaning effect can be maintained regardless of the number of wipe nozzles 41 to which the cleaning liquid is to be discharged.

  Further, in this embodiment, the pressure applied to the cleaning liquid tank 73 is changed to eight stages more than the number of flow rate adjustment valves and opening / closing valves as components by the combination of the opening / closing states of the three opening / closing valves 72a, 72b, 72c. It is possible. As described above, the pressure applied to the cleaning liquid tank 73 can be adjusted by a combination of the open / close signals of the three open / close valves 72a, 72b, 72c smaller than the number of the wipe nozzles 41, so that the control system is not complicated.

  Even if the number of wipe nozzles for discharging the cleaning liquid varies by adjusting the flow rate of the cleaning liquid by providing a flow rate adjusting valve in the supply line of the cleaning liquid to the wipe nozzle, the ink is supplied from one wipe nozzle to the lower surface of the inkjet head 2. It is also conceivable to keep the flow rate of the cleaning liquid to be constant. However, in recent years, solutions that are highly soluble in rubber products and the like used in liquid feed pipes are often used as ink agents and cleaning agents. From special materials that have liquid resistance to these solutions. When the flow regulating valve and the liquid feeding pipe are adopted, there is a problem that the printing apparatus is expensive. In the printing apparatus according to the present invention, the discharge pressure (flow rate) of the cleaning liquid can be adjusted by disposing the flow rate adjustment valve and the on-off valve in the pipeline branched from the supply pipe connected to the air supply source 51. It is not necessary to consider the resistance to the solution used for the cleaning liquid in selecting the regulating valve and the on-off valve, and the apparatus can be configured at low cost.

DESCRIPTION OF SYMBOLS 1 Printing unit 2 Inkjet head 5 Printing paper 6 Guide roller 10 Recording head 11 Inkjet head support plate 14 Cleaning head holding part 20 Cleaning liquid supply mechanism 40 Cleaning unit 41 Wipe nozzle 42 Wiper blade 43 Cleaning head 51 Air supply source 52 Air supply pipe 53 Air Supply pipe 61 Main tank 62 Sub tank 71 Flow rate adjusting valve 72 Open / close valve 73 Cleaning liquid tank 74 Manifold 75 Open / close valve 80 Control unit 81 Cleaning control unit 82 Print control unit 83 Moving mechanism 84 Vertical mechanism

Claims (5)

In a printing apparatus having a liquid supply mechanism for supplying a cleaning liquid for cleaning an ink discharge head to the discharge head,
The liquid supply mechanism is
A reservoir for storing the cleaning liquid;
A liquid supply pipe for supplying liquid from the reservoir to the cleaning unit by the action of compressed air;
A cleaning unit provided with a wipe nozzle that jets cleaning liquid toward the discharge head;
An air supply pipe for allowing compressed air from an air supply source to flow into the storage section;
A discharge pipe branched from the air supply pipe and communicating with the atmosphere;
An on-off valve inserted in the discharge pipe;
A flow rate adjusting valve that is inserted in the discharge pipe and adjusts the flow rate of compressed air discharged from the discharge pipe when the on-off valve is opened;
Control means for adjusting the flow rate of the compressed air that flows into the storage unit by discharging compressed air to the atmosphere at a flow rate set in the flow rate adjustment valve by controlling the open / close state of the open / close valve;
A printing apparatus comprising: The printing apparatus according to claim 1,
The cleaning unit is provided with a plurality of wipe nozzles branched from a liquid supply pipe for supplying a cleaning liquid, and a liquid supply on / off valve interposed between the wipe nozzle and the branched liquid supply pipe,
The air supply pipe is provided with a plurality of discharge pipes,
The control means is configured to control the opening of the liquid supply on / off valve according to the number of wipe nozzles for ejecting the cleaning liquid during the cleaning operation among the plurality of wipe nozzles, and to insert the liquid supply on / off valve into each of the plurality of discharge pipes. The printing apparatus which adjusts the flow volume of the compressed air which flows in into the said storage part by controlling the number which opens an on-off valve. The printing apparatus according to claim 2,
The flow rate adjustment valve inserted in each of the plurality of discharge pipes is set to a different flow rate,
The said control means is a printing apparatus which adjusts the flow volume of the compressed air which flows in into the said storage part in multiple steps with the combination of the open / closed state of the said on-off valve inserted in these discharge pipes. A liquid supply method for supplying a cleaning liquid to a cleaning unit for cleaning a discharge head in which a nozzle for discharging a liquid is formed by pressure of compressed air flowing from an air supply source into a cleaning liquid reservoir,
Setting a flow rate of a flow rate adjusting valve inserted into a discharge pipe communicating with the atmosphere branched from an air supply pipe for supplying compressed air to the storage section, and opening and closing the on-off valve inserted in the discharge pipe By adjusting the flow rate of the compressed air that is discharged to the atmosphere at the flow rate set in the flow rate adjustment valve, and flows into the storage unit,
A liquid supply method comprising: The liquid supply method according to claim 4,
Among a plurality of wipe nozzles that eject cleaning liquid toward the discharge head disposed in the cleaning unit, the number of wipe nozzles that eject cleaning liquid during a cleaning operation, and an air supply pipe that supplies compressed air to the reservoir The plurality of the liquid supply pressures for applying a predetermined liquid supply pressure corresponding to the number of the wipe nozzles according to the flow rate setting of the flow rate adjusting valve respectively inserted into the plurality of discharge pipes communicating with the more branched atmosphere. Further comprising a step of determining a combination of open / close states of the open / close valves respectively inserted in the discharge pipes,
The liquid supply method of adjusting the flow rate of the compressed air that flows into the storage section by opening and closing the on-off valve based on a combination of on-off states of the on-off valve.

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