JP2016187884A - Ink supply device, image recording device, and ink supply method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink supply device, an image recording device, and an ink supply method which can switch an ink tank quickly by shortening a delay time to detect a decrease of a remaining amount of ink in the ink tank.SOLUTION: An ink supply device 50 includes a pump 83 for forming a liquid flow, and a load detection part 84 for acquiring a variable reflecting a load on the pump 83. When the variable acquired by the load detection part 84 satisfies a predetermined condition and decreases, a control part determines that a remaining amount of ink in an ink tank in use decreases, and switches a supply source of the ink to the other ink tank 60 from the ink tank 60 in use. Thus, a delay time to detect a decrease of the remaining amount can be shortened. Therefore, a time to switch the ink tank can be reduced.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an ink supply apparatus that supplies ink to a predetermined supply destination while switching an ink supply source between a plurality of ink tanks, an image recording apparatus including the ink supply apparatus, and an ink supply method.

  2. Description of the Related Art Conventionally, there is known an ink jet type image recording apparatus that records an image on a printing paper by ejecting ink from a plurality of recording heads while conveying a long belt-like printing paper. In this type of image recording apparatus, different colors of ink are ejected from a plurality of recording heads. Then, a color image is recorded on the recording surface of the printing paper by superimposing single-color images formed by ink of each color.

  Also, this type of image recording apparatus is provided with an ink supply device that supplies ink of each color. The ink supply device supplies ink to a recording tank or a storage tank provided on the upstream side of the recording head while switching an ink supply source between the plurality of ink tanks. A conventional ink supply device is described in Patent Document 1, for example.

JP 2010-194915 A

  In the conventional ink supply device, when one ink tank becomes empty, the ink supply source is switched to another ink tank and the ink supply is continued. Then, while supplying ink from another ink tank, the emptied ink tank is replaced with a new ink tank. This reduces the operating time loss associated with ink tank replacement.

  Conventionally, a timeout method has been used to detect whether or not the ink tank in use has become empty. For example, when an increase in the amount of ink in the storage tank at the supply destination takes a longer time than the scheduled time, it is determined that the ink tank in use has become empty. However, in such a timeout method, since the detection is not completed until the scheduled time comes after the ink tank is emptied, the delay time for detection is large. Thus, if it takes a long time to detect a decrease in the remaining amount of ink in the ink tank, switching to another ink tank is delayed, resulting in a loss of operating time.

  The present invention has been made in view of such circumstances, and an ink supply device capable of quickly switching between ink tanks by shortening a delay time required for detecting a decrease in the remaining amount of ink in the ink tank. An object of the present invention is to provide an image recording apparatus and an ink supply method.

  In order to solve the above problems, a first invention of the present application is an ink supply device that supplies ink to a predetermined supply destination while switching an ink supply source among a plurality of ink tanks, and is connected to the supply destination. A main pipe, a plurality of branch pipes connected to the plurality of ink tanks, a switching unit that selectively connects one of the plurality of branch pipes to the main pipe, and the main pipe A pump that forms a liquid flow toward the supply destination, a load detection unit that acquires a variable that reflects a load applied to the pump, and a control unit that controls the load detection unit and the switching unit. And the control unit controls the switching unit when the variable acquired by the load detection unit is reduced to satisfy a preset condition, so that the supply source ink tank is replaced with another ink tank. Switch to.

  A second invention of the present application is the ink supply device according to the first invention, wherein the load detection unit acquires a drive current supplied to the pump as the variable.

  A third invention of the present application is the ink supply device of the first invention or the second invention, wherein the control unit is in a state where the variable acquired by the load detection unit is lower than a preset threshold value. When continuing for a preset allowable time or longer, the switching unit is controlled to switch the supply source ink tank to another ink tank.

  A fourth invention of the present application is the ink supply apparatus according to any one of the first to third inventions, wherein the supply destination is a count tank that repeats the storage of ink and the discharge of a certain amount.

  A fifth invention of the present application is the ink supply device according to any one of the first to fourth inventions, wherein an exchange detection unit that detects that the used ink tank has been exchanged for a new ink tank is provided. Further, the switching unit includes an on-off valve provided in each of the plurality of branch pipes, and the control unit detects whether the other ink tank has been replaced after the replacement detection unit detects replacement of the ink tank. Until it is used, the pump is operated while opening the on-off valve on the branch pipe connected to the new ink tank, and the inside of the branch pipe connected to the new ink tank is opened. Fill with ink.

  6th invention of this application is an ink supply apparatus of 4th invention, Comprising: It further has the replacement | exchange detection part which detects having replaced | exchanged the said used ink tank for a new ink tank, The said switching part is the said switch | An opening / closing valve provided in each of a plurality of branch pipes, and the control unit detects whether the other ink tank is used after the replacement detection unit detects the replacement of the ink tank. The on-off valve on the branch pipe connected to the ink tank is closed, and the pump is operated while the on-off valve on the branch pipe connected to the new ink tank is opened. The ink for one time is supplied.

  A seventh invention of the present application is an image recording apparatus for recording an image on the surface of a recording medium, the ink supply device according to any one of the first to sixth inventions, and the supply destination or the supply destination. And a recording head that discharges ink stored in a tank provided on the downstream side of the recording medium onto the surface of the recording medium.

  An eighth invention of the present application is an ink supply method for supplying ink to a predetermined supply destination while switching an ink supply source between a plurality of ink tanks, and a) driving a pump provided on a pipe. A step of supplying ink from one of the plurality of ink tanks of the supply source to the supply destination; b) acquiring a variable reflecting a load applied to the pump; c) And a step of switching the ink tank of the supply source to another ink tank when the condition is lowered while satisfying a preset condition.

  A ninth invention of the present application is the ink supply method of the eighth invention, wherein in the step b), the drive current supplied to the pump is acquired as the variable.

  According to the first to ninth aspects of the present application, a decrease in the remaining amount of ink in the ink tank in use is determined based on the load applied to the pump. As a result, the delay time for detecting the remaining amount can be shortened. Accordingly, it is possible to shorten the time required for switching the ink tank.

  In particular, according to the second and ninth inventions of the present application, the pump load can be detected using the drive current without separately generating a signal reflecting the pump load.

  In particular, according to the third invention of the present application, it is possible to more accurately determine a decrease in the remaining amount of ink in the ink tank.

  In particular, according to the fourth invention of the present application, it is possible to grasp the amount of ink supplied to the downstream side based on the number of ink discharges from the count tank. Further, it is possible to determine a decrease in the remaining amount of ink in the ink tank in use regardless of the time required for storing ink in the count tank.

  In particular, according to the fifth aspect of the present invention, after the ink tank is replaced with a new ink tank, the ink in the new ink tank is preliminarily placed in the branch pipe before the other ink tank is used up. Fill. In this way, it is possible to shorten the time until the ink in the new ink tank is supplied to the supply destination after the other ink tank is used.

  In particular, according to the sixth invention of the present application, after the ink tank is replaced with a new ink tank and before another ink tank is used, the supply of one ink to the count tank is newly performed. From an ink tank. At that time, ink in a new ink tank is filled into the branch pipe. In this way, it is possible to shorten the time until the ink in a new ink tank is supplied to the count tank after the other ink tank is used.

It is the figure which showed the structure of the image recording device. It is the figure which showed the structure of the ink supply apparatus. It is the figure which showed the connection structure of a control part and each part in an image recording device. 3 is a flowchart showing a flow of primary supply of ink from an ink tank to a count tank. It is the flowchart which showed the flow of prior filling.

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

<1. Configuration of Image Recording Device>
FIG. 1 is a diagram showing a configuration of an image recording apparatus 1 according to an embodiment of the present invention. The image recording apparatus 1 discharges ink from a plurality of recording heads 30 toward the printing paper 9 while transporting the printing paper 9 that is a long band-like recording medium, to the recording surface of the printing paper 9. An inkjet printing apparatus that records a color image. As shown in FIG. 1, the image recording apparatus 1 includes an image recording apparatus main body 10, four ink supply apparatuses 50, and a control unit 90.

<1-1. About Image Recording Device Main Body>
The image recording apparatus main body 10 includes a transport mechanism 20, four recording heads 30, and four subtanks 40. The transport mechanism 20 is a mechanism that transports the printing paper 9 in the transport direction along the longitudinal direction thereof. The transport mechanism 20 according to the present embodiment includes an unwinding unit 21, a plurality of transport rollers 22, and a winding unit 23. The printing paper 9 is fed out from the unwinding unit 21 and is conveyed along a conveyance path constituted by a plurality of conveyance rollers 22. Each conveyance roller 22 guides the printing paper 9 to the downstream side of the conveyance path by rotating around the horizontal axis while being in contact with the printing paper 9. Further, the printed printing paper 9 is collected to the winding unit 23.

  As shown in FIG. 1, the printing paper 9 moves below the four recording heads 30 and substantially parallel to the arrangement direction of the four recording heads 30. At this time, the recording surface of the printing paper 9 is directed upward (on the recording head 30 side). Further, the printing paper 9 is stretched over the plurality of transport rollers 22 in a state where tension is applied. Thereby, slack and wrinkles of the printing paper 9 during conveyance are suppressed.

  The four recording heads 30 are arranged at equal intervals along the conveyance path of the printing paper 9. Each recording head 30 has a plurality of nozzles arranged in parallel with the width direction of the printing paper 9 (horizontal direction orthogonal to the transport direction). The four recording heads 30 have C (cyan), M (magenta), Y (yellow), and K (black) color components that are color components of a color image from a plurality of nozzles toward the recording surface of the printing paper 9. Ink droplets (hereinafter referred to as “ink droplets”) are each ejected.

  The four sub tanks 40 are containers for storing ink before ejection. The four sub tanks 40 store inks of C, M, Y, and K colors. Each of the four recording heads 30 is connected to a sub tank 40 that stores ink of a color to be ejected via a pipe. Ink supplied from an ink supply device 50 described later is temporarily stored in a sub tank 40 disposed inside the image recording apparatus main body 10. Each recording head 30 ejects ink stored in the sub tank 40 from a plurality of nozzles according to an image to be recorded.

  Thus, the four recording heads 30 each record a single color image on the recording surface of the printing paper 9 by ejecting ink droplets. A color image is formed on the upper surface of the printing paper 9 by superimposing the four monochrome images.

  Note that a drying processing unit for drying the ink ejected on the recording surface of the printing paper 9 may be further provided on the downstream side in the transport direction of the recording head 30. For example, the drying processing unit blows a heated gas toward the printing paper 9 to vaporize the solvent in the ink attached to the printing paper 9 to dry the ink. However, the drying processing unit may dry the ink by other methods such as light irradiation.

<1-2. About ink supply device>
The four ink supply devices 50 are devices that supply ink of each color from the ink tank 60 (FIG. 2) installed outside the image recording apparatus main body 10 to the four sub tanks 40. The four ink supply devices 50 have the same configuration although the colors of the supplied ink are different from each other. Therefore, hereinafter, the configuration of one ink supply device 50 will be described. In the following description, the upstream side of the ink supply path is simply referred to as “upstream side”, and the downstream side of the ink supply path is simply referred to as “downstream side”.

  FIG. 2 is a diagram showing the configuration of one ink supply device 50. As shown in FIG. 2, the ink supply device 50 includes a first tank holder 51, a second tank holder 52, a liquid feeding pipe 53, a count tank 54, and an intermediate tank 55.

  The first tank holder 51 and the second tank holder 52 are pedestal portions for supporting the ink tank 60 in which ink is stored. The ink tank 60 serving as an ink supply source is set on the upper surface of each of the first tank holder 51 and the second tank holder 52. Each ink tank 60 has a bottle portion 61 for storing ink and an IC chip 62 attached to the bottle portion 61. Identification information for distinguishing the ink tank 60 from other ink tanks 60 is recorded in the IC chip 62. The first tank holder 51 and the second tank holder 52 have reader units 511 and 521 that read identification information from the IC chip 62.

  The liquid feeding pipe 53 is a pipe for supplying ink from the ink tank 60 to the sub tank 40 in the image recording apparatus main body 10. As shown in FIG. 2, the liquid feeding pipe 53 includes a first branch pipe 71, a second branch pipe 72, a first main pipe 73, a second main pipe 74, and a third main pipe 75.

  The upstream end of the first branch pipe 71 is connected to the ink tank 60 set in the first tank holder 51. The upstream end of the second branch pipe 72 is connected to the ink tank 60 set in the second tank holder 52. The downstream end of each of the first branch pipe 71 and the second branch pipe 72 is connected to the upstream end of the first main pipe 73. The downstream end of the first main pipe 73 is connected to the count tank 54.

  A first on-off valve 81 is provided on the path of the first branch pipe 71. A second on-off valve 82 is provided on the path of the second branch pipe 72. In the present embodiment, the first on-off valve 81 and the second on-off valve 82 function as a switching unit that selectively connects one of the two branch pipes 71, 72 to the first main pipe 73.

  When the second on-off valve 82 is closed and the first on-off valve 81 is opened, the ink tank 60 set in the first tank holder 51 and the first main pipe 73 are connected to each other through the first branch pipe 71. Is done. Hereinafter, this state is referred to as a “first connection state”. On the other hand, when the first on-off valve 81 is closed and the second on-off valve 82 is opened, the ink tank 60 and the first main pipe 73 set in the second tank holder 52 flow through the second branch pipe 72. Road connected. Hereinafter, this state is referred to as a “second connection state”.

  A first liquid feed pump 83 is provided in the first main pipe 73. The first liquid feed pump 83 forms a liquid flow toward the downstream side (count tank 54 side) in the first main pipe 73. When the first liquid feed pump 83 is driven in the first connection state described above, the count tank passes from the ink tank 60 set in the first tank holder 51 through the first branch pipe 71 and the first main pipe 73. Ink is supplied to 54. Further, when the first liquid feed pump 83 is driven in the second connection state described above, the ink tank 60 set in the second tank holder 52 passes through the second branch pipe 72 and the first main pipe 73. Ink is supplied to the count tank 54.

  The first liquid feed pump 83 forms a liquid flow by the power of the motor. When the load (ink resistance) applied to the first liquid feed pump 83 changes, the drive current supplied to the motor also changes. The first liquid feed pump 83 is connected to a current detection circuit 84 that detects a drive current supplied to the motor. When the remaining amount of ink in the ink tank 60 of the supply source decreases and becomes close to an empty state, the load applied to the first liquid feed pump 83 decreases, so the drive current supplied to the motor also decreases. The current detection circuit 84 detects the change in the drive current. That is, in the present embodiment, the current detection circuit 84 serves as a load detection unit that acquires the value of the drive current that is a variable reflecting the load applied to the first liquid feeding pump 83.

  The detection signal of the current detection circuit 84 is output to the control unit 90 described later. Note that an amplifier circuit for amplifying the detection signal may be provided between the current detection circuit 84 and the control unit 90.

  The count tank 54 is a container that repeatedly stores ink and discharges a predetermined amount. The control unit 90 described later can grasp the amount of ink supplied to the intermediate tank 55 described later based on the number of ink discharges from the count tank 54. The count tank 54 is provided with a lower limit sensor 541 and an upper limit sensor 542. The lower limit sensor 541 detects whether or not a preset lower limit amount of ink is stored in the count tank 54. The upper limit sensor 542 detects whether or not a preset upper limit amount of ink is stored in the count tank 54.

  The upstream end of the second main pipe 74 is connected to the count tank 54. The downstream end of the second main pipe 74 is connected to the intermediate tank 55. A third on-off valve 85 is interposed on the path of the second main pipe 74. The intermediate tank 55 is disposed at a position lower than the count tank 54. Therefore, when the third opening / closing valve 85 is opened, the ink stored in the count tank 54 is supplied to the intermediate tank 55 through the second main pipe 74.

  The intermediate tank 55 is a container for storing ink discharged from the count tank 54. The intermediate tank 55 serves as a buffer for temporarily storing ink and preventing ink shortage on the downstream side. The intermediate tank 55 is provided with a lower limit sensor 551. The lower limit sensor 551 detects whether or not a preset lower limit amount of ink is stored in the intermediate tank 55.

  The upstream end of the third main pipe 75 is connected to the intermediate tank 55. The downstream end of the third main pipe 75 is connected to the sub tank 40 in the image recording apparatus main body 10. A second liquid feed pump 86, a fourth on-off valve 87, a filter 88, and a deaeration unit 89 are provided on the path of the third main pipe 75. The second liquid feed pump 86 forms a liquid flow toward the downstream side (sub tank 40 side) in the third main pipe 75. When the fourth on-off valve 87 is opened and the second liquid feed pump 86 is driven, the ink stored in the intermediate tank 55 is supplied to the sub tank 40 through the third main pipe 75.

  Foreign matter in the ink flowing through the third main pipe 75 is removed by the filter 88. Further, the dissolved gas in the ink is removed in the deaeration unit 89. The deaeration unit 89 removes dissolved gas in the ink by, for example, reducing the pressure while stirring the ink.

<1-3. About the control unit>
The control unit 90 is means for controlling the operation of each unit in the image recording apparatus 1. As conceptually shown in FIG. 1, the control unit 90 includes a computer having an arithmetic processing unit 91 such as a CPU, a memory 92 such as a RAM, and a storage unit 93 such as a hard disk drive. A computer program P is installed in the storage unit 93 to execute the ink supply operation in the ink supply device 50 and the ink discharge operation in the image recording apparatus main body 10.

  FIG. 3 is a diagram illustrating a connection configuration between the control unit 90 and each unit in the image recording apparatus 1. As shown in FIG. 3, the control unit 90 includes the transport mechanism 20, the recording head 30, the first on-off valve 81, the second on-off valve 82, the first liquid feed pump 83, the current detection circuit 84, and the third on-off valve. 85, the second liquid feed pump 86, the fourth on-off valve 87, the deaeration unit 89, the reader units 511 and 521, the lower limit sensor 541, the upper limit sensor 542, and the lower limit sensor 551 are electrically connected to each other.

  The control unit 90 temporarily reads the computer program P stored in the storage unit 93 into the memory 92, and the arithmetic processing unit 91 performs arithmetic processing based on the computer program P, thereby controlling the operation of each unit described above. To do. As a result, the ink supply operation in the ink supply device 50 and the ink discharge operation in the image recording apparatus main body 10 proceed.

<2. Ink supply operation>
Next, the ink supply operation in the ink supply device 50 will be described. In this ink supply device 50, ink is supplied from the ink tank 60 to the count tank 54 (primary supply), ink is supplied from the count tank 54 to the intermediate tank 55 (secondary supply), and the intermediate tank 55 is supplied to the sub tank 40. Ink supply (tertiary supply) is appropriately executed.

<2-1. About secondary supply and tertiary supply>
First, the secondary supply and tertiary supply of ink will be described.

  The control unit 90 operates the second liquid feeding pump 86 in accordance with the required amount of ink in the image recording apparatus main body 10. As a result, the tertiary supply of ink from the intermediate tank 55 to the sub tank 40 is executed. Further, when the control unit 90 determines that the amount of ink in the intermediate tank 55 has reached the lower limit amount based on the detection signal of the lower limit sensor 551 provided in the intermediate tank 55, the control unit 90 opens the third on-off valve 85. Thereby, the secondary supply of ink from the count tank 54 to the intermediate tank 55 is executed. When the controller 90 determines that the amount of ink in the count tank 54 has reached the lower limit amount based on the detection signal of the lower limit sensor 541 provided in the count tank 54 after opening the third on-off valve 85, 3 The on-off valve 85 is closed. Thereby, the supply amount of ink in the secondary supply is made constant.

<2-2. About primary supply>
Next, the primary supply of ink from the ink tank 60 to the count tank 54 will be described. The ink supply source in the primary supply is the ink tank 60 set in the first tank holder 51 or the ink tank 60 set in the second tank holder 52. The ink supply destination in the primary supply is the count tank 54.

  FIG. 4 is a flowchart showing a flow of primary supply of ink from the ink tank 60 to the count tank 54. In the flowchart of FIG. 4, at the time of step S1, one of the first on-off valve 81 and the second on-off valve 82 is opened, the other is closed, and the first liquid feed pump 83 is stopped. .

  As the secondary supply of ink from the count tank 54 to the intermediate tank 55 proceeds, the amount of ink in the count tank 54 gradually decreases. First, the controller 90 determines whether the ink tank 60 has been replaced in the first tank holder 51 or the second tank holder 52 from the previous primary supply to the current time (step S1). Whether or not the ink tank 60 is replaced is determined based on whether or not the identification number of the IC chip 62 read from the reader units 511 and 521 has been changed. That is, in the present embodiment, the reader units 511 and 521 function as replacement detection units that detect that the used ink tank 60 has been replaced with a new ink tank 60.

  When the ink tank 60 has not been replaced (no in step S1), the control unit 90 reduces the amount of ink in the count tank 54 based on the detection signal of the lower limit sensor 541 provided in the count tank 54. It is monitored whether or not the limit amount has been reached (step S2). If the amount of ink in the count tank 54 is larger than the lower limit amount (no in step S2), the process returns to step S1 to determine again whether or not the ink tank 60 has been replaced.

  On the other hand, when it is determined that the amount of ink in the count tank 54 has reached the lower limit amount based on the detection signal of the lower limit sensor 541 (yes in step S2), the control unit 90 performs the first on-off valve 81 and the second on-off valve. The drive of the 1st liquid feeding pump 83 is started, without switching the open / close state of 82 (step S3). As a result, the supply of ink from the ink tank 60 to the count tank 54 is started, which is the same as when the previous primary supply was completed.

  Thereafter, the control unit 90 determines whether or not the remaining amount of ink in the ink tank 60 has approached an empty state based on the detection signal of the current detection circuit 84 (step S4). In step S4, the control unit 90 monitors whether the value of the drive current detected by the current detection circuit 84 has decreased below a preset threshold value. Then, when the state in which the value of the drive current is lower than the threshold value continues for a preset allowable time (for example, 1 second), it is determined that the remaining amount of ink in the ink tank 60 has approached an empty state. (Yes in step S4).

  In that case, the control unit 90 switches the open / close state of the first open / close valve 81 and the second open / close valve 82. At this time, the driving of the first liquid feed pump 83 may be continued or may be temporarily stopped. As a result, the ink tank 60 that is the supply source is switched from the ink tank 60 that is supplying ink to the other ink tank 60 (step S5). For example, when ink is supplied from the ink tank 60 set in the first tank holder 51 immediately before step S5, the first on-off valve 81 is closed and the second on-off valve 82 is opened. Thereby, the connection state of the pipe is changed so that ink is supplied from the ink tank 60 set in the second tank holder 52.

  On the other hand, if the value of the drive current is not lower than the threshold value, or if the state does not continue for a preset allowable time even if the drive current value is lower than the threshold value, the control unit 90 performs the ink in the ink tank 60. It is determined that the remaining amount has not yet approached the empty state (no in step S4).

  In the case of no in step S4 or after the switching in step S5 is completed, the control unit 90 determines the amount of ink stored in the count tank 54 based on the detection signal of the upper limit sensor 542 of the count tank 54. It is determined whether or not the upper limit amount has been reached (step S6). Until the amount of ink in the count tank 54 reaches the upper limit (no in step S6), the drive of the first liquid feed pump 83 is continued, the process returns to step S4, and the control unit 90 performs step S4. The determination process of S6 is repeated. When it is determined that the amount of ink in the count tank 54 has reached the upper limit (yes in step S6), the control unit 90 stops the first liquid feed pump 83 and ends the primary supply of ink. (Step S7).

  Thereafter, upon restart, the process returns to step S1, and the control unit 90 again determines whether or not the ink tank 60 has been replaced, and monitors the amount of ink in the count tank 54.

  As described above, the ink supply device 50 performs the primary supply of the ink to the count tank 54 while switching the ink supply source between the two ink tanks 60. This shortens the time during which the primary supply is stopped as the ink tank 60 is replaced. In particular, in the ink supply device 50, when the drive current value reflecting the load of the first liquid feed pump 83 falls to satisfy a preset condition, the ink remaining amount in the ink tank 60 in use is reduced. Judge that it is close to empty. For this reason, the delay time required for detecting the decrease in the remaining amount of the ink tank 60 is made shorter than the case where the decrease in the remaining amount of the ink tank 60 is detected by the timeout method based on the time required for storing the ink in the count tank 54. be able to. Accordingly, the ink tank 60 can be switched more quickly.

  If the time required for switching the ink tank 60 is shortened, the depletion of ink in the intermediate tank 55 is less likely to occur. Therefore, the ink consumption speed in the image recording apparatus main body 10 can be increased without changing the buffer capacity of the intermediate tank 55. Further, the capacity of the intermediate tank 55 can be reduced without changing the ink consumption speed.

  In particular, in this embodiment, the value of the drive current supplied to the first liquid feed pump 83 is monitored as a variable reflecting the load of the first liquid feed pump 83. In this way, the load of the first liquid feed pump 83 can be detected using the drive current without separately generating a signal reflecting the load of the first liquid feed pump 83. However, separately from the drive current, a signal reflecting the load of the first liquid feed pump 83 may be generated, and a decrease in the remaining amount of the ink tank 60 may be determined based on the signal.

  In the present embodiment, when the state where the value of the drive current is lower than a preset threshold value continues for a preset allowable time or longer, the remaining amount of ink in the ink tank 60 is empty. Judge that approached. In this way, it is possible to accurately determine the decrease in the remaining amount of ink in the ink tank 60 without reacting to temporary signal disturbance. However, if the value of the drive current is stable, it may be determined that the remaining amount of the ink tank 60 has decreased without waiting for an allowable time. The condition for determining the decrease in the remaining amount of the ink tank 60 is not necessarily as described above.

<2-3. About pre-filling>
On the other hand, if it is determined that the ink tank 60 has been replaced in step S <b> 1 described above, the ink supply device 50 performs a “preceding filling” process that fills the branch pipe connected to the new ink tank 60 with ink. Perform (step SA). Below, this prior filling is demonstrated, referring the flowchart of FIG.

  When performing pre-filling, first, the control unit 90 switches the open / close state of the first open / close valve 81 and the second open / close valve 82. Thereby, the ink tank 60 of the supply source is switched from the ink tank 60 used for the previous primary supply to the other ink tank 60 (step SA1). For example, when the ink tank 60 set in the first tank holder 51 is used for the previous primary supply, and the ink tank 60 is replaced in the second tank holder 52, the first on-off valve 81 is closed. At the same time, the second on-off valve 82 is opened. Thereby, the ink supply path is switched to the new ink tank 60 after the replacement.

  Next, the control unit 90 monitors whether or not the amount of ink in the count tank 54 has reached the lower limit amount based on the detection signal of the lower limit sensor 541 provided in the count tank 54 (step SA2). When the amount of ink in the count tank 54 is larger than the lower limit amount (no in step SA2), the monitoring in step SA2 is continued. When it is determined that the amount of ink in the count tank 54 has reached the lower limit amount based on the detection signal of the lower limit sensor 541 (yes in step SA2), the control unit 90 starts driving the first liquid feed pump 83. (Step SA3). As a result, the supply of ink from the new ink tank 60 after replacement to the count tank 54 is started.

  Subsequently, the control unit 90 determines whether or not the amount of ink stored in the count tank 54 has reached the upper limit amount based on the detection signal of the upper limit sensor 542 of the count tank 54 (step SA4). . Until the amount of ink in the count tank 54 reaches the upper limit amount (no in step SA4), the drive of the first liquid feed pump 83 is continued and the control unit 90 repeats the determination process in step SA4. .

  When it is determined that the amount of ink in the count tank 54 has reached the upper limit (yes in step SA4), the controller 90 stops the first liquid feed pump 83 (step SA5). Thereafter, the control unit 90 switches the open / close state of the first open / close valve 81 and the second open / close valve 82 again. Thereby, the ink tank 60 of the supply source is returned from the new ink tank 60 after replacement to the ink tank 60 used for the primary supply before Step SA1 (Step SA6).

  As described above, in the present embodiment, the primary supply is performed only once from the new ink tank 60 after the replacement as the pre-filling in Step SA. In this way, the ink is filled into the branch pipe connected to the new ink tank 60. For this reason, when the other ink tank 60 is used and the ink tank 60 is switched in the subsequent step S5, it is possible to shorten the time until the switched ink is supplied to the count tank 54. As a result, the primary supply stop time associated with the switching of the ink tank 60 can be further shortened.

  Note that the prior filling may be performed by other methods. For example, in the primary supply after the ink tank 60 is replaced, the first liquid supply pump 83 is driven and both the first on-off valve 81 and the second on-off valve 82 are opened for a certain period of time, whereby the ink after the replacement is replaced. The branch pipe connected to the tank 60 may be filled with ink. In addition, during the period when ink is not supplied to the count tank 54 (between step S7 and the next step S2), the open / close valve on the ink tank 60 side after replacement is opened and the first liquid feed pump 83 is turned on. The branch pipe connected to the ink tank 60 after replacement may be filled with ink by driving for a certain time.

  However, if the primary supply for one time is performed from the replaced ink tank 60 as shown in FIG. 5, the amount of ink sucked from the ink tank 60 by the primary supply for one time and the pre-filling are consumed. The amount of ink to match. For this reason, it is preferable in terms of easy management of the ink consumption by the pre-filling.

  Further, the timing for executing the pre-filling is not necessarily the time when the first primary supply after the replacement of the ink tank 60 is performed. The pre-filling is performed somewhere in a plurality of processing cycles of FIG. 4 performed until the other ink tank 60 is used after the leader unit 511 or the reader unit 521 detects the replacement of the ink tank 60. Just do it.

<3. Modification>
Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

  The ink supply device 50 supplies ink to the sub tank 40 in three stages of primary supply, secondary supply, and tertiary supply. However, the ink supply device 50 may supply ink in one or two stages, or may perform supply operations in four or more stages. Therefore, the “supply destination” in the present invention is not necessarily limited to the count tank 54, and may be the intermediate tank 55 or the sub tank 40.

  In addition, the control unit 90 sets the ink supply amount in the secondary supply to be constant based on the detection signal of the lower limit sensor 541, but opens the third on-off valve 85 for a predetermined time regardless of the lower limit sensor. By providing a timer or the like, the ink supply amount in the secondary supply may be constant.

  The ink supply device 50 supplies ink while switching the ink supply source between the two ink tanks 60. However, the number of ink tanks 60 to be switched as the supply source may be three or more. In that case, the ink supply device 50 may have three or more branch pipes depending on the number of ink tanks 60.

  The ink used in the present invention may be either water-based or oil-based ink. In addition, the ink used in the present invention may be a type of ink that dries when the solvent evaporates, or may be a UV curable ink that cures when irradiated with ultraviolet rays.

  In the above embodiment, the four recording heads 30 are provided in the image recording apparatus main body 10. However, the number of recording heads 30 in the image recording apparatus main body 10 may be 1 to 3, or 5 or more. For example, in addition to C, M, Y, and K colors, a head that discharges special color inks may be provided. The ink supply device 50 only needs to be provided for each color of ink used.

  The image recording apparatus 1 records an image on a printing paper 9 as a recording medium. However, the image recording apparatus of the present invention may record an image on a sheet-like recording medium other than general paper (for example, a resin film, metal foil, glass, etc.).

  In addition, the ink supply device 50 is configured to supply ink to one image recording device 1. However, ink is supplied to a plurality of image recording devices by providing means for appropriately switching the ink supply path. It is possible.

  Moreover, you may combine suitably each element which appeared in said embodiment and modification in the range which does not produce inconsistency.

DESCRIPTION OF SYMBOLS 1 Image recording apparatus 9 Printing paper 10 Image recording apparatus main body 20 Conveying mechanism 21 Unwinding part 22 Conveying roller 23 Winding part 30 Recording head 40 Sub tank 50 Ink supply apparatus 51 First tank holder 52 Second tank holder 53 Liquid supply piping 54 Count tank 55 Intermediate tank 60 Ink tank 61 Bottle part 62 IC chip 71 First branch pipe 72 Second branch pipe 73 First main pipe 74 Second main pipe 75 Third main pipe 81 First on-off valve 82 Second on-off valve 83 1st liquid feed pump 84 Current detection circuit 85 3rd on-off valve 86 2nd liquid feed pump 87 4th on-off valve 88 Filter 89 Deaeration part 90 Control part 511 Reader part 521 Reader part 541 Lower limit sensor 542 Upper limit sensor 551 Lower limit sensor P Computer program

Claims (9)

An ink supply device that supplies ink to a predetermined supply destination while switching an ink supply source between a plurality of ink tanks,
A main pipe connected to the supply destination;
A plurality of branch pipes connected to the plurality of ink tanks;
A switching unit that selectively connects one of the plurality of branch pipes to the main pipe;
A pump provided on the main pipe for forming a liquid flow toward the supply destination;
A load detector that acquires a variable reflecting the load applied to the pump;
A control unit for controlling the load detection unit and the switching unit;
With
The control unit controls the switching unit to switch the ink tank of the supply source to another ink tank when the variable acquired by the load detection unit is lowered while satisfying a preset condition. Ink supply device. The ink supply device according to claim 1,
The load detection unit is an ink supply device that acquires a drive current supplied to the pump as the variable. The ink supply device according to claim 1 or 2,
The control unit controls the switching unit to control the supply source when the state where the variable acquired by the load detection unit is lower than a preset threshold value continues for a preset allowable time or longer. Ink supply device for switching one ink tank to another ink tank. The ink supply device according to any one of claims 1 to 3, wherein
The supply destination is an ink supply device that is a count tank that repeats the storage and discharge of a certain amount of ink. The ink supply device according to any one of claims 1 to 4, wherein:
A replacement detection unit for detecting that the used ink tank has been replaced with a new ink tank;
The switching unit includes an on-off valve provided in each of the plurality of branch pipes,
The control unit includes an on-off valve on the branch pipe connected to the new ink tank after the replacement detection unit detects the replacement of the ink tank and before another ink tank is used. An ink supply device that fills the inside of the branch pipe connected to the new ink tank with ink by operating the pump while opening the valve. The ink supply device according to claim 4,
A replacement detection unit for detecting that the used ink tank has been replaced with a new ink tank;
The switching unit includes an on-off valve provided in each of the plurality of branch pipes,
The control unit includes an on-off valve on the branch pipe connected to another ink tank until the other ink tank is used after the replacement detection unit detects the replacement of the ink tank. An ink supply device that closes and supplies the ink to the count tank by operating the pump while opening the on-off valve on the branch pipe connected to the new ink tank. An image recording apparatus for recording an image on a surface of a recording medium,
An ink supply device according to any one of claims 1 to 6,
A recording head for discharging ink stored in a tank provided on the downstream side of the supply destination or the supply destination onto the surface of the recording medium;
An image recording apparatus. An ink supply method for supplying ink to a predetermined supply destination while switching an ink supply source between a plurality of ink tanks,
a) driving a pump provided on a pipe to supply ink from one of the plurality of ink tanks of the supply source to the supply destination;
b) obtaining a variable reflecting a load applied to the pump;
c) a step of switching the ink tank of the supply source to another ink tank when the variable is reduced while satisfying a preset condition;
An ink supply method. The ink supply method according to claim 8, comprising:
In the step b), an ink supply method for acquiring a drive current supplied to the pump as the variable.

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