Liquid dispensing device and control method for liquid dispensing device

Abstract

There was a risk that the system would not be able to detect issues such as media floating occurring downstream of the liquid discharge section in the transport direction, including the location of the liquid discharge section. [Solution] The liquid dispensing device includes a conveying unit that has a belt provided with an adhesive and conveys a medium on the belt in a conveying direction, a liquid dispensing unit that dispenses liquid onto the medium, and a first sensor that detects a first height of the medium placed on the belt, located between the position where the liquid is dispensed by the liquid dispensing unit and the position where the medium is peeled off the belt in the conveying direction.

Description

Technical Field

[0001] The present invention relates to a liquid ejection device and a method for controlling the liquid ejection device.

Background Art

[0002] Conventionally, as shown in Patent Document 1, there is known a liquid ejection device including an adhesive belt that conveys a medium in a conveyance direction, a liquid ejection unit that ejects liquid onto the conveyed medium, and a sensor that detects floating of the medium or the like upstream in the conveyance direction of the liquid ejection unit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the liquid ejection device described in Patent Document 1 may not be able to detect floating of the medium or the like that occurs downstream in the conveyance direction of the liquid ejection unit including the position of the liquid ejection unit.

Means for Solving the Problems

[0005] The liquid ejection device includes a conveyance unit having a belt provided with an adhesive, which places a medium on the belt and conveys it in a conveyance direction, a liquid ejection unit that ejects liquid onto the medium, and a first sensor that detects a first height of the medium placed on the belt and located between a position where the liquid is ejected by the liquid ejection unit and a position where the medium is peeled off from the belt in the conveyance direction.

[0006] A control method for a liquid dispensing device comprises: a conveying unit having a belt provided with an adhesive, which conveys a medium on the belt in a conveying direction; a liquid dispensing unit which dispenses liquid onto the medium; a first sensor which detects a first height of the medium placed on the belt, located in the conveying direction between the position where liquid is dispensed by the liquid dispensing unit and the position where the medium is peeled off the belt; a pressing unit which is located upstream of the liquid dispensing unit in the conveying direction and presses the medium against the belt; and a second sensor which detects a second height of the medium placed on the belt, located in the conveying direction between the position where the medium is pressed against the belt by the pressing unit and the position where liquid is dispensed by the liquid dispensing unit. The control method for a liquid dispensing device comprises: a conveying unit having a belt provided with an adhesive, which conveys a medium on the belt in a conveying direction; a liquid dispensing unit having a conveying unit having a belt on which a medium is placed on the belt; a liquid dispensing unit having a conveying unit having a belt on which a medium is placed on the belt; a first sensor which detects a second height of the medium placed on the belt, located in the conveying direction between the position where the medium is pressed against the belt by the pressing unit and the position where liquid is dispensed by the liquid dispensing unit. The control method for a liquid dispensing device comprises: a conveying unit having a belt on which an adhesive is provided, which conveys a medium on the belt in a conveying direction; a liquid dispensing unit which discharges liquid onto the medium; a first sensor which detects a first height of the medium placed on the belt in a conveying direction and has located a belt on which a medium is placed on the belt [Brief explanation of the drawing]

[0007] [Figure 1] A schematic diagram showing a cross-section of a liquid dispensing device. [Figure 2] A schematic diagram showing the top view of a liquid dispensing device. [Figure 3] A flowchart illustrating the control of a liquid dispensing device. [Modes for carrying out the invention]

[0008] The embodiments will be described below with reference to the drawings. In the drawings, directions will be described using a three-dimensional coordinate system in which the X, Y, and Z axes are mutually orthogonal. In this case, the direction along the X axis will be called the X direction, the direction along the Y axis will be called the Y direction, and the direction along the Z axis will be called the Z direction. For the sake of explanation, the positive Z direction will be referred to as the up direction or simply up, and the negative Z direction as the down direction or simply down; the positive X direction will be referred to as the right direction or simply right, and the negative X direction as the left direction or simply left; and the positive Y direction will be referred to as the forward direction or simply forward, and the negative Y direction as the backward direction or simply backward.

[0009] 1. Configuration of the liquid dispensing device As shown in Figure 1, the liquid dispensing device 1 comprises a dispensing unit 21, a first feed roller 22, a transport unit 20, a pressure roller 23 which is a pressing unit, a liquid dispensing unit 10, a sensor group 30 which consists of multiple sensors arranged in front of and behind the liquid dispensing unit 10, a second feed roller 24, a winding unit 25, and the like, arranged from upstream to downstream in the transport direction D of the medium M. The liquid dispensing device 1 also comprises a control unit 13 and a notification unit 14. The configuration of the liquid dispensing device 1 will be described with reference to Figure 2.

[0010] The medium M is, for example, a long piece of fabric made of natural or synthetic fibers. This long piece of fabric is also called a raw material roll. The liquid dispensing device 1 records onto the medium M. The recording onto the fabric is also called printing, and the medium M is also called the material to be printed. The medium M may also be ordinary paper, synthetic paper, or film.

[0011] The feeding unit 21 feeds out the medium M wound on the first roll body M1 before recording using a feeding motor (not shown). The medium M is then conveyed in the conveying direction D by the conveying unit 20, with its angle changed by the first feed roller 22. The conveying unit 20 has a first roller, the drive roller 20b, positioned upstream in the conveying direction D, and a second roller, the driven roller 20c, positioned downstream in the conveying direction D.

[0012] The transport unit 20 uses a transport motor (not shown) to rotate the drive roller 20b counterclockwise, and the driven roller 20c also rotates counterclockwise in response. The endless belt 20a, which is stretched between the drive roller 20b and the driven roller 20c, also rotates counterclockwise, which is the circumferential direction. The outer circumferences of the drive roller 20b and the driven roller 20c are in contact with the inner surface of the belt 20a. Note that the relationship between the drive roller 20b and the driven roller 20c may be reversed.

[0013] The outer surface of the belt 20a is coated with a glue G, which is an adhesive, and is therefore tacky. The glue G is composed of, for example, a silicone resin. The belt 20a allows the medium M to be adhesively fixed using glue G, and enables stable transport of the medium M on it.

[0014] The medium M placed on the belt 20a of the transport unit 20 is subjected to a pressing force P by the pressure roller 23, from the upper recording surface toward the belt 20a. The lower transport surface of the medium M is pressed against the belt 20a by the pressing force P, and is fixed to the belt 20a by the adhesive force of the glue G. The pressure roller 23 is positioned upstream of the transport direction D of the liquid discharge unit 10.

[0015] The liquid ejection unit 10 is composed of an inkjet type head (not shown) and is mounted on the carriage 11. The carriage 11 includes a carriage motor (not shown). The liquid ejection device 1 can be fitted with ink cartridges or ink tanks that store inks of various colors, such as CMYK (Cyan, Magenta, Yellow, Black). The liquid ejection unit 10 includes a supply mechanism (not shown) that supplies ink from an ink cartridge or the like to the print head. The supply mechanism supplies ink of each color from the ink cartridge or the like to the corresponding nozzles of the print head.

[0016] The liquid ejection unit 10 moves back and forth along the carriage axis 12, together with the carriage 11, on the medium M by the carriage motor. The head of the liquid ejection unit 10 moves on the medium M under control based on recorded data from the control unit 13, ejecting liquid ink from the nozzle, which can be recorded on the recording surface of the medium M. Furthermore, the ink colors can be any combination of four or more colors, including, for example, shades of CMYK.

[0017] The liquid ejection unit 10 ejects ink, and the recorded medium M is transported downstream while being adhesively fixed to the belt 20a. Furthermore, the medium M is transported to the winding unit 25 with its angle changed by the second feed roller 24. At this time, due to the winding force of the winding unit 25, the medium M is pulled upward downstream in the conveying direction D. Due to the tension applied to the medium M, the medium M is peeled off from the belt 20a. Here, the position where the medium M is peeled off from the belt 20a is referred to as the peeling position, and is shown as the third position C in FIGS. 1 and 2. The winding unit 25 can wind up the medium M peeled off from the belt 20a as the second roll body M2.

[0018] In addition, the liquid ejection device 1 may include a cleaning unit that cleans the surface of the belt 20a after the medium M is peeled off with a cleaning liquid, a wiping unit that wipes off the cleaning liquid, a drying unit that dries the cleaning liquid (all not shown in the figures), and the like.

[0019] The control unit 13 is configured to include a CPU (Central Processing Unit) that comprehensively controls each part of the liquid ejection device 1, a UART (Universal Asynchronous Receiver Transmitter) that manages input / output, an FPGA (Field Programmable Gate Array) that is a logic circuit, a PLD (Programmable Logic Device), and the like. The CPU is also referred to as a processor. The control unit 13 is configured to include a storage unit such as a flash ROM (Read Only Memory) that is a rewritable non-volatile memory, an HDD (Hard Disk Drive), and a RAM (Random Access Memory) that is a volatile memory. The CPU of the control unit 13 reads out programs such as firmware stored in the non-volatile memory of the storage unit and executes them using the volatile memory of the storage unit as a work area.

[0020] The liquid ejection device 1 may include a communication unit (not shown in the figures) that can communicate with, for example, a smartphone, a tablet terminal, a computer, and the like. The control unit 13 can control the liquid ejection unit 10, the conveying unit 20, and the like based on the information received from the communication unit and record on the medium M. The notification unit 14 includes a liquid crystal display for displaying various information, a speaker for transmitting information by voice, a buzzer, etc. The notification unit 14 may be a touch panel display having an input unit. The notification unit 14 is a so-called user interface.

[0021] 2. Configuration of Sensors The sensor group 30 is configured to include a first sensor 31, a second sensor 32, and a third sensor 33. Each sensor of the sensor group 30 is arranged downstream of the pressure roller 23 in the conveyance direction D of the medium M.

[0022] Each sensor can detect the height, which is the vertical position of the medium M placed on the belt 20a. That is, each sensor can detect the height of the medium M based on the position of the belt 20a. Note that the gap between the liquid ejection unit 10 and the belt 20a is narrow, and there is a possibility of detecting the ink ejected from the liquid ejection unit 10. Therefore, each sensor is preferably arranged at a position avoiding the liquid ejection unit 10 in the conveyance direction D.

[0023] Here, as shown in FIGS. 1 and 2, the liquid ejection device 1 sets a second position B, a first position A, and a third position C in this order from upstream to downstream as predetermined positions in the conveyance direction D of the medium M on the belt 20a. Specifically, the first position A is the position of the downstream end where liquid is ejected onto the medium M by the liquid ejection unit 10 in the conveyance direction D of the medium M. The second position B is the position of the upstream end where liquid is ejected onto the medium M by the liquid ejection unit 10 in the conveyance direction D of the medium M. The third position C is the aforementioned peeling position where the medium M is peeled off from the belt 20a.

[0024] The first sensor 31 is capable of detecting a first height H1 of the medium M located between a first position A and a third position C in the transport direction D of the medium M. That is, the first sensor 31 detects a first height H1 of the medium M placed on the belt 20a located between the position where liquid is discharged by the liquid discharge unit 10 and the peeling position, which is the position where the medium M is peeled off the belt 20a, in the transport direction D of the medium M. In this embodiment, the first sensor 31 is positioned between a first position A and a third position C in the transport direction D of the medium M.

[0025] The second sensor 32 is capable of detecting the second height H2 of the medium M, which is located between the pressure roller 23 and the second position B in the transport direction D of the medium M. That is, the second sensor 32 detects the second height H2 of the medium M placed on the belt 20a, which is located between the position where the medium M is pressed against the belt 20a by the pressure roller 23 and the position where the liquid is discharged by the liquid discharge unit 10, in the transport direction D of the medium M. In this embodiment, the second sensor 32 is positioned between the pressure roller 23 and the second position B in the transport direction D of the medium M.

[0026] The third sensor 33 is capable of detecting the third height H3 of the medium M, which is located at the second position B in the transport direction D of the medium M. That is, the third sensor 33 detects the third height H3 of the medium M placed on the belt 20a, which is located between the position where the first sensor 31 detects the first height H1 of the medium M and the position where the second sensor 32 detects the second height H2 of the medium M, in the transport direction D of the medium M. In this embodiment, the third sensor 33 is positioned at the second position B in the transport direction D of the medium M.

[0027] Incidentally, the adhesive strength of the glue G may decrease due to deterioration of the belt 20a, wear and tear of the glue G applied to the belt 20a, or adhesion of foreign matter to the belt 20a or the glue G. When the adhesive strength of the glue G decreases, the medium M becomes more likely to separate from the belt 20a. As a result, the medium M may partially separate from the belt 20a, and so-called floating of the medium M may occur, as shown in Figures 1 and 2.

[0028] When ink is dispensed onto the recording surface of the medium M by the liquid dispensing unit 10, the ink may penetrate to the transport surface of the medium M. In other words, ink can get between the belt 20a and the transport surface of the medium M, and the adhesive strength of the glue G may decrease. As a result, floating of the medium M is more likely to occur downstream of the liquid discharge unit 10 in the transport direction D, including the position of the liquid discharge unit 10. In particular, floating of the medium M is more likely to occur when the amount of ink discharged by the liquid discharge unit 10 is large.

[0029] Furthermore, downstream of the liquid discharge section 10 in the transport direction D, tension is applied to the medium M due to the winding force of the winding section 25, as described above. This tension acts in a direction that separates the medium M from the belt 20a. As a result, the floating F of the medium M is more likely to occur. Thus, due to factors such as ink ejection and the winding force of the winding section 25, floating of the medium M is more likely to occur downstream of the liquid ejection section 10 in the transport direction D, including the position of the liquid ejection section 10.

[0030] Referring to Figure 2, each sensor in the sensor group 30 will be described in detail. Here, each sensor is a transmissive-type photosensor. For example, the first sensor 31 is composed of a combination of a first light-emitting element 31a and a first light-receiving element 31b. The first sensor 31 has the first light-emitting element 31a on the right and the first light-receiving element 31b on the left, with a belt 20a on which a medium M can be placed in between. The first sensor 31 emits a first detection light R1 from the first light-emitting element 31a toward the left, which is the cross-section of the medium M. The first light-receiving element 31b of the first sensor 31 receives the first detection light R1, thereby enabling the detection of the first height H1 of the medium M.

[0031] If there is no floating F of the medium M between the first light-emitting element 31a and the first light-receiving element 31b, the first detection light R1 is not blocked. The first sensor 31 can detect that the first detection light R1 received by the first light-receiving element 31b does not decrease. The first sensor 31 can detect a first height H1 as the height at which the medium M is not floating F, by detecting that the first detection light R1 does not decrease.

[0032] On the other hand, if there is a floating F of the medium M between the first light-emitting element 31a and the first light-receiving element 31b, the first detection light R1 is blocked according to the height of the floating F. As a result, the first sensor 31 can detect a first height H1, which is the height of the floating F of the medium M, by decreasing the first detection light R1 received by the first light-receiving element 31b.

[0033] The second sensor 32 and the third sensor 33 have the same configuration as the first sensor 31 described above. The second sensor 32 emits a second detection light R2 from the second light-emitting element 32a, which is received by the second light-receiving element 32b, thereby detecting the second height H2 of the medium M. The third sensor 33 emits a third detection light R3 from the third light-emitting element 33a, which is received by the third light-receiving element 33b, thereby detecting the third height H3 of the medium M. Furthermore, if the distance between the light-emitting element and the light-receiving element of each sensor is long, a lens may be used for detection light.

[0034] 3. Control method for liquid dispensing device The control unit 13 controls the liquid discharge unit 10, the transport unit 20, etc., based on information received from the communication unit or input to the input unit of the notification unit 14, and starts processing such as transporting the medium M and recording.

[0035] As described above, the control unit 13 transports the medium M in the transport direction D using the transport unit 20. As shown in Figure 3, the control unit 13 detects the second height H2 of the medium M being transported on the belt 20a using the second sensor 32 (S101). Specifically, the second sensor 32 detects the second height H2 of the medium M at a position upstream of the second position B on the belt 20a in the transport direction D. As mentioned above, the second position B is the upstream end position in the transport direction D of the medium M where liquid is discharged into the medium M by the liquid discharge unit 10.

[0036] Next, the control unit 13 detects the first height H1 of the medium M placed on the belt 20a using the first sensor 31 (S102). Specifically, the first sensor 31 detects a first height H1 of the medium M between a first position A and a third position C on the belt 20a. As described above, the first position A is the downstream end position in the transport direction D of the medium M where liquid is discharged into the medium M by the liquid discharge unit 10. The third position C is the position where the medium M is detached from the belt 20a.

[0037] As mentioned above, downstream of the liquid discharge unit 10 in the transport direction D, the adhesive strength of the glue G tends to decrease due to the ink discharged onto the medium M. Also, downstream of the liquid discharge unit 10 in the transport direction D, the winding force of the winding unit 25 applies tension in a direction that separates the medium M from the belt 20a. As a result, the floating F of the medium M is more likely to occur.

[0038] Therefore, the first sensor 31 detects the first height H1 of the medium M between the first position A and the third position C on the belt 20a, which is downstream of the conveying direction D of the liquid discharge section 10 where the floating F of the medium M is likely to occur. On the other hand, the second sensor 32 detects the second height H2 of the medium M at a position upstream in the transport direction D from the second position B on the belt 20a, where the floating F of the medium M is less likely to occur.

[0039] The control unit 13 calculates the difference between the detected first height H1 and the second height H2, and compares the absolute value of this difference with a predetermined threshold (S103). Hereinafter, this predetermined threshold will be referred to as the first threshold. The first threshold is used to determine the height of the floating F of the medium M. The first threshold is the acceptable height of the floating F of the medium M. The first threshold value is stored in the memory unit of the control unit 13, and the CPU of the control unit 13 can read it from the memory unit and process it.

[0040] The control unit 13 can determine that there is floating F in the medium M if the absolute value of the difference is greater than the first threshold (S103: YES), and the notification unit 14 notifies the information to that effect (S105), and the process ends. At this time, the control unit 13 can determine that the lifting F of the medium M has occurred due to at least one of the following factors: deterioration of the belt 20a, depletion of the glue G, adhesion of foreign matter to the belt 20a or glue G, or a decrease in the adhesive strength of the glue G. The control unit 13 may also notify the notification unit 14 of information relating to at least one of these factors.

[0041] Furthermore, the control unit 13 may determine that the media M is floating F due to an excessive amount of ink being ejected by the liquid ejection unit 10. The control unit 13 may also notify the notification unit 14 of this fact. The information communicated by the notification unit 14, as described above, is also referred to as alert information that draws attention to the user of the liquid dispensing device 1.

[0042] On the other hand, if the absolute value of the difference is less than or equal to the first threshold (S103:NO), the control unit 13 compares the detected first height H1 with a predetermined threshold (S104). Hereinafter, this predetermined threshold will be referred to as the second threshold. The second threshold is used to determine the height of the floating F of the medium M. The second threshold is the acceptable height of the floating F of the medium M. The second threshold value is set appropriately according to the type of medium M and is stored in the memory of the control unit 13. The CPU of the control unit 13 can read this value from the memory and process it.

[0043] The control unit 13 can determine that there is floating F in the medium M if the detected first height H1 is greater than the second threshold (S104: YES), and the notification unit 14 notifies the information to that effect (S105), and the process ends. In this case, the control unit 13 may notify the aforementioned alert information via the notification unit 14.

[0044] Furthermore, if the detected first height H1 is less than or equal to the second threshold (S104: NO), the control unit 13 can determine that there is no floating F of the medium M, or that the floating F of the medium M is acceptable, and terminate the process. In this case, the control unit 13 may notify the notification unit 14 that there is no floating F of the medium M, or that the floating F of the medium M is acceptable.

[0045] The detected first height H1 and second height H2 include the thickness of the medium M. The control unit 13 can eliminate the influence of the thickness of the medium M by calculating the difference between the detected first height H1 and the second height H2.

[0046] Depending on the type of media M, the thickness of the media M may vary. Therefore, for example, the second threshold value corresponding to a thin media M is set to a smaller value than the second threshold value corresponding to a thick media M. However, when changing the type of media M used for recording, the second threshold value may not be changed to an appropriate value due to user error or an error in the control unit 13.

[0047] For example, when the type of recording medium M is changed from a thin medium M to a thick medium M, the second threshold value may not change from the value corresponding to the thin medium M to the value corresponding to the thick medium M. In this case, the control unit 13 will compare the first height H1 of the thick medium M with the second threshold value corresponding to the thin medium M. As a result, even if the height of the floating F is within the range that is normally acceptable for the thick medium M, it may exceed the second threshold value corresponding to the thin medium. This may cause the control unit 13 to mistakenly determine that there is an unacceptable floating F in the thick medium M.

[0048] Thus, when changing the type of recording medium M, if the second threshold value is not changed to an appropriate value according to the type of medium M, the control unit 13 may mistakenly determine that there is an unacceptable amount of floating F in the medium M, even if the floating F of the medium M is within an acceptable range.

[0049] However, the control unit 13 can cancel out the thickness of the medium M contained in both by calculating the difference between the first height H1 and the second height H2. In other words, the control unit 13 can eliminate the thickness of the medium M and obtain the height of the floating medium M corresponding to the difference F. In this way, the control unit 13 can detect the floating F of the medium M that occurs downstream of the liquid discharge unit 10 in the transport direction D of the liquid discharge unit 10, including the position of the liquid discharge unit 10, using the first sensor 31 and the second sensor 32. Furthermore, since the thickness of the medium M can be eliminated, the first threshold value, which is compared with the height of the floating F of the medium M corresponding to the difference, does not need to be changed depending on the type of medium M, thus preventing misjudgment by the control unit 13.

[0050] Here, when comparing the absolute value of the difference between the first height H1 and the second height H2 with the first threshold, there is a risk that there may be unacceptable floating F of the medium M even if the absolute value of the difference is less than or equal to the first threshold. For example, even if the heights of the first height H1 and the second height H2 are such that the floating F of the medium M is unacceptable, if the absolute value of the difference is less than or equal to the first threshold, the control unit 13 may mistakenly determine that there is no floating F of the medium M, or that the floating F of the medium M is acceptable. However, the control unit 13 compares the first height H1 with the second threshold if the absolute value of the difference is less than or equal to the first threshold. This prevents misjudgments by the control unit 13.

[0051] Furthermore, if the second threshold is sufficiently greater than the thickness of the medium M, the influence of the thickness of the medium M is small, and therefore the control unit 13 does not need to exclude the thickness of the medium M. In this case, the control unit 13 can use only the first height H1 obtained from the first sensor 31. By comparing the first height H1 with a second threshold, the control unit 13 can detect the floating F of the medium M occurring downstream of the liquid discharge unit 10 in the transport direction D of the liquid discharge unit 10, including the position of the liquid discharge unit 10. Furthermore, the control unit 13 can perform the same processing even if the type of medium M does not change.

[0052] In these cases, the control unit 13 can determine that there is an unacceptable floating F of the medium M when the first height H1 is greater than the second threshold, and the notification unit 14 can notify alert information as described above. In this way, the control unit 13 can detect the floating F of the medium M that occurs downstream of the liquid discharge unit 10 in the transport direction D of the liquid discharge unit 10, including the position of the liquid discharge unit 10, using the first sensor 31.

[0053] On the other hand, the control unit 13 can determine that there is no floating F of the medium M, or that the floating F of the medium M is acceptable, when the first height H1 is less than or equal to the second threshold. In this case, the control unit 13 may notify the notification unit 14 that there is no floating F of the medium M, or that the floating F of the medium M is acceptable.

[0054] By the way, although not shown in the diagram, when the liquid dispensing unit 10 moves from side to side, if there are floats F on the left and right ends of the medium M, the ends of the medium M may get caught and curl up. In particular, if the head of the liquid dispensing unit 10 is compatible with multi-color nozzles, the liquid dispensing unit 10 also becomes longer in the transport direction D, making it easier for the ends of the medium M to get caught and curl up.

[0055] The liquid dispensing device 1 needs to detect as quickly as possible any floating F of the medium M that causes it to curl up near the liquid dispensing unit 10, because otherwise normal recording to the medium M would be impossible. The first sensor 31 is configured to detect the first height H1 of the medium M located between the first position A and the third position C, which are downstream of the liquid dispensing unit 10. Therefore, there is a high possibility that the detection of the floating F of the medium M that causes it to curl up near the liquid dispensing unit 10 will be delayed. Similarly, the second sensor 32 is configured to detect the second height H2 of the medium M located upstream of the liquid dispensing unit 10. Therefore, it is difficult for the second sensor 32 to detect the floating F of the medium M that causes it to curl up near the liquid dispensing unit 10.

[0056] Therefore, as shown in Figures 1 and 2, the third sensor 33 detects the third height H3 of the medium M, which is located at the second position B, the upstream end position where liquid is discharged into the medium M by the liquid discharge unit 10, in the transport direction D of the medium M. In other words, in order to detect the floating F of the medium M that causes it to curl up as early as possible, the third sensor 33 detects the third height H3 of the medium M at the second position B, which is as close as possible upstream to the liquid discharge section 10. The third sensor 33 detects the third height H3 of the medium M at a position between the position where the first sensor 31 detects the first height H1 of the medium M and the position where the second sensor 32 detects the second height H2 of the medium M in the transport direction D of the medium M.

[0057] The control by the control unit 13 in the case of curling up the medium M, as described below, is similar to the control by the control unit 13 in the case of floating the medium M F, so a flowchart is omitted. The control unit 13 starts processing such as transporting and recording the medium M using the liquid discharge unit 10 and the transport unit 20. The third sensor 33 emits a third detection light R3 from the third light-emitting element 33a, and the third light-receiving element 33b receives the light to detect the third height H3 of the medium M placed on the belt 20a.

[0058] The control unit 13 calculates the difference between the detected third height H3 and the second height H2, and compares the absolute value of this difference with a predetermined threshold. Hereinafter, this predetermined threshold will be referred to as the third threshold. The third threshold is used to determine the height of the media M's lift F that causes curling. The third threshold is the acceptable height of the media M's lift F. The third threshold value is stored in the memory unit of the control unit 13, and the CPU of the control unit 13 can read it from the memory unit and process it.

[0059] The control unit 13 can determine that there is a lifting F of the medium M that causes curling if the absolute value of the difference is greater than the third threshold, and the notification unit 14 notifies the system of this fact and terminates the process. At this time, the control unit 13 can determine that the lifting F of the medium M has occurred due to at least one of the following factors: deterioration of the belt 20a, depletion of the glue G, adhesion of foreign matter to the belt 20a or glue G, or a decrease in the adhesive strength of the glue G. The control unit 13 may also notify the user of information relating to at least one of these factors as alert information via the notification unit 14.

[0060] On the other hand, the control unit 13 compares the detected third height H3 with a predetermined threshold if the absolute value of the difference is less than or equal to the third threshold. Hereinafter, this predetermined threshold will be referred to as the fourth threshold. The fourth threshold is used to determine the height of the media M's lift F that causes curling. The fourth threshold is the acceptable height of the media M's lift F. The fourth threshold value is appropriately set according to the type of medium M and is stored in the memory of the control unit 13. The CPU of the control unit 13 can read this value from the memory and process it.

[0061] The control unit 13 can determine that there is a lifting F of the medium M causing the curling up when the detected third height H3 is greater than the fourth threshold, and the notification unit 14 notifies the system of this fact and terminates the process. In this case, the control unit 13 may notify the aforementioned alert information via the notification unit 14.

[0062] Furthermore, if the detected third height H3 is less than or equal to the fourth threshold, the control unit 13 can determine that there is no floating F of the medium M, or that the floating F of the medium M is acceptable, and terminate the process. In this case, the control unit 13 may notify the notification unit 14 that there is no floating F of the medium M, or that the floating F of the medium M is acceptable.

[0063] The control unit 13 can cancel out the thickness of the medium M contained in both by calculating the difference between the third height H3 and the second height H2. In other words, the control unit 13 can eliminate the thickness of the medium M and obtain the height of the floating medium M corresponding to the difference F. In this way, the control unit 13 can detect the floating F of the medium M that causes turbulence near the liquid discharge unit 10 using the third sensor 33 and the second sensor 32. Furthermore, because the thickness of the medium M can be eliminated, the third threshold value, which is compared with the height of the floating F of the medium M corresponding to the difference, does not need to be changed depending on the type of medium M, thus preventing misjudgment by the control unit 13.

[0064] In this case, when comparing the absolute value of the difference between the third height H3 and the second height H2 with the third threshold, there is a risk that there may be unacceptable floating F of the medium M even if the absolute value of the difference is less than or equal to the third threshold. For example, even if the heights of the third height H3 and the second height H2 are such that the floating F of the medium M is unacceptable, if the absolute value of the difference is less than or equal to the third threshold, the control unit 13 may mistakenly determine that there is no floating F of the medium M, or that the floating F of the medium M is acceptable. However, the control unit 13 compares the third height H3 with the fourth threshold if the absolute value of the difference is less than or equal to the third threshold. This prevents misjudgments by the control unit 13.

[0065] Furthermore, if the fourth threshold is sufficiently greater than the thickness of the medium M, the influence of the thickness of the medium M is small, and therefore the control unit 13 does not need to exclude the thickness of the medium M. In this case, the control unit 13 can use only the third height H3 obtained by the third sensor 33. By comparing the third height H3 with the fourth threshold, the control unit 13 can detect the floating F of the medium M that causes uplift in the vicinity of the liquid discharge unit 10. Furthermore, the control unit 13 can perform the same processing even if the type of medium M does not change.

[0066] In these cases, the control unit 13 can determine that there is an unacceptable floating F of the medium M when the third height H3 is greater than the fourth threshold, and the notification unit 14 can notify alert information as described above. In this way, the control unit 13 can detect the floating F of the medium M that occurs downstream of the liquid discharge unit 10 in the transport direction D of the liquid discharge unit 10, including the position of the liquid discharge unit 10, using the first sensor 31.

[0067] On the other hand, the control unit 13 can determine that there is no floating F of the medium M, or that the floating F of the medium M is acceptable, when the first height H1 is less than or equal to the second threshold. In this case, the control unit 13 may notify the notification unit 14 that there is no floating F of the medium M, or that the floating F of the medium M is acceptable.

[0068] The liquid dispensing device 1 according to the above embodiment includes a conveying unit 20 that has a belt 20a on which glue G is provided and conveys the medium M on the belt 20a in the conveying direction D, a liquid dispensing unit 10 that dispenses ink onto the medium M, and a first sensor 31 that detects a first height H1 of the medium M placed on the belt 20a, located in the conveying direction D between the position where the liquid is dispensed by the liquid dispensing unit 10 and the position where the medium M is peeled off the belt 20a.

[0069] The first sensor 31 can detect the floating of the medium M that occurs downstream of the liquid discharge unit 10 in the transport direction D of the liquid discharge unit 10, including the position of the liquid discharge unit 10.

[0070] Although embodiments have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments and may be modified, substituted, deleted, etc., as long as it does not depart from the spirit of this invention. Both the second sensor 32 and the third sensor 33 detect the height of the medium M upstream of the liquid discharge unit 10. Therefore, when the control unit 13 calculates the difference from the first height H1, it may choose not to use the second sensor 32, but instead use the third sensor 33 which is located near the liquid discharge unit 10.

[0071] The first sensor 31 does not necessarily have to be positioned between the first position A and the third position C in the transport direction D of the medium M. The first sensor 31 is not particularly limited in its position as long as it can detect the first height H1 of the medium M, which is located between the first position A and the third position C in the transport direction D of the medium M.

[0072] The second sensor 32 does not necessarily have to be positioned between the pressure roller 23 and the second position B in the transport direction D of the medium M. The second sensor 32 is not particularly limited in its position as long as it can detect the second height H2 of the medium M, located between the pressure roller 23 and the second position B in the transport direction D of the medium M.

[0073] The third sensor does not necessarily have to be located at the second position B in the transport direction D of the medium M. The third sensor 33 is not particularly limited in its placement as long as it can detect the third height H3 of the medium M located at the second position B.

[0074] Each sensor in the sensor group 30 was described using the example of a transmissive photosensor, but a reflective photosensor may also be used. In this case, for example, the first sensor 31 can be configured by installing multiple reflective photosensors in the left-right direction and arranging them so as to illuminate the recording surface of the medium M from above with detection light. Each sensor in the sensor group 30 may be an ultrasonic sensor. In this case, the ultrasonic sensor is configured to include a transmitting unit, which is a transmitter that transmits a wave instead of a light-emitting element, and a receiving unit, which is a receiver that receives a wave instead of a light-receiving element. [Explanation of symbols]

[0075] 1...Liquid dispensing device, 10...Liquid dispensing unit, 11...Carriage, 13...Control unit, 14...Notification unit, 20...Conveying unit, 20a...Belt, 20b...Driven roller, 20c...Driven roller, 23...Pressure roller, 25...Winding unit, 30...Sensor group, 31...First sensor, 32...Second sensor, 33...Third sensor, H1...First height, H2...Second height, H3...Third height, G...Glue, M...Media.

Claims

1. A conveying unit having a belt on which an adhesive is provided, and which places a medium on the belt and conveys it in the conveying direction, A liquid dispensing unit for dispensing liquid into the aforementioned medium, A liquid dispensing device comprising: a first sensor for detecting a first height of the medium placed on the belt, located between the position where the liquid is dispensed by the liquid dispensing unit and the position where the medium is peeled off the belt in the conveying direction.

2. In the aforementioned transport direction, a pressing unit is located upstream of the liquid discharge unit and presses the medium against the belt, A second sensor for detecting the second height of the medium placed on the belt, located between the position where the medium is pressed against the belt by the pressing portion and the position where the liquid is discharged by the liquid discharge portion, in the aforementioned conveying direction, A liquid dispensing device according to claim 1, comprising: a control unit that determines that the medium is floating when the absolute value of the difference between the first height and the second height is greater than a first threshold;

3. The liquid dispensing device according to claim 2, wherein the control unit determines that the medium is floating when the first height is greater than the second threshold.

4. The liquid dispensing device according to claim 2, further comprising a third sensor for detecting a third height of the medium placed on the belt, located between a position where the first sensor detects the first height of the medium and a position where the second sensor detects the second height of the medium in the conveying direction.

5. The liquid dispensing device according to claim 4, wherein the control unit determines that the medium is floating when the absolute value of the difference between the second height and the third height is greater than the third threshold.

6. The liquid dispensing device according to claim 5, wherein the control unit determines that the medium is floating when the third height is greater than a fourth threshold.

7. Equipped with a news department, The liquid dispensing device according to any one of claims 2 to 6, wherein the control unit determines that the medium is floating and the notification unit notifies alert information.

8. A conveying unit having a belt on which an adhesive is provided, and which places a medium on the belt and conveys it in the conveying direction, A liquid dispensing unit for dispensing liquid into the aforementioned medium, In the aforementioned transport direction, a first sensor for detecting the first height of the medium placed on the belt is located between the position where the liquid is discharged by the liquid discharge unit and the position where the medium is peeled off the belt, In the aforementioned transport direction, a pressing unit is located upstream of the liquid discharge unit and presses the medium against the belt, A control method for a liquid dispensing device comprising: a second sensor for detecting a second height of the medium placed on the belt, located between the position where the medium is pressed against the belt by the pressing portion and the position where the liquid is dispensed by the liquid dispensing portion in the conveying direction; A control method for a liquid dispensing device, comprising comparing the absolute value of the difference between the first height and the second height with a first threshold, and determining that the medium is floating if the absolute value of the difference between the first height and the second height is greater than the first threshold.

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