Ink supply device, ink supply method, and inkjet printer

Abstract

The present invention accurately detects an ink residual amount in a tank for storing ink in an ink supply device with a simple configuration having a low maintenance cost. A tank support mechanism (330) configured to rotate in accordance with the weight of an ink tank (32) by using a plate-like member (331) that can rotate around a rotation shaft (331a) and an elastic member (332) is provided on a base-like portion (31a) of a body (31) of an ink supply device 30 of an inkjet printing device. A label (51) of a QR code (registered trademark) in which ink information is recorded is attached to a back surface (32B) of the ink tank (32). In a control unit (100), image analysis is performed using imaging data obtained with a camera (41) for imaging the label (51). The inclination of the ink tank (32) is determined, for example, on the basis of the interval between the upper side and the lower side of the label (51) in the captured image, and the remaining amount of ink in the ink tank (32) is determined from the inclination.

Description

Ink supply device, ink supply method, and inkjet printing device

[0001] The present invention relates to an ink supply device and an inkjet printing device equipped with the same, and more particularly to detecting the amount of ink remaining in an ink tank that stores ink in an ink supply device.

[0002] Inkjet printing devices form images on a recording medium, such as a long sheet of printing paper, by ejecting ink onto the recording medium. Typically, C (cyan), M (magenta), Y (yellow), and K (black) inks are used as the inks ejected onto the recording medium. For example, commercial inkjet printing devices are provided with ink supply devices that supply the C, M, Y, and K inks separately from the printing device itself. The ink supply devices include tanks (also referred to as "main tanks") that store the C, M, Y, and K inks, as well as pumps for transporting the C, M, Y, and K inks. The remaining ink levels in each tank are detected while the inkjet printing device is in operation.

[0003] In such a configuration, methods for detecting the remaining amount of ink in each tank include, for example, a method of calculating the amount of ink based on the operating time of a pump for moving ink in the tank, a method of detecting the ink level in the tank using a float, etc. Also known are methods of optically detecting the position of the ink level in the tank using the shading, transmission, or refraction of light from a light source, and methods of capturing an image of the ink level using an imaging device (see, for example, Japanese Patent Application Laid-Open Nos. 2008-200955 and 2020-19243).

[0004] Japanese Patent Publication No. 2008-200955 Japanese Patent Publication No. 2020-19243 Japanese Patent Publication No. 2020-49660

[0005] Among the conventional methods for detecting the remaining ink level in a tank (hereinafter referred to as "ink tank") that stores ink used in an inkjet printing device, the method of calculating the remaining ink level from the operating time of a pump does not necessarily provide sufficient accuracy in detecting the remaining ink level because the pump's liquid delivery capacity fluctuates due to factors such as the pump's start-up time and deterioration over time. Furthermore, the method of detecting the ink level in an ink tank using a float has problems such as the durability of the float and the need for regular cleaning. Furthermore, the method of detecting the ink level using a float, the method of optically detecting the ink level, and the method of capturing an image of the ink level require specialized components to implement these methods.

[0006] Therefore, it is desirable to accurately detect the remaining amount of ink in a tank that stores ink in an ink supply device using a simple configuration with low maintenance costs.

[0007] A first aspect of the present invention is an ink supply device comprising: a tank for storing ink; a support mechanism including an elastic member for supporting a bottom surface of the tank, and supporting the tank such that the vertical position or tilt of the tank changes according to the weight of the tank; an imaging unit that images the tank and generates imaging data showing at least a portion of the tank; an image analysis unit that determines the vertical position or tilt based on the imaging data; and a remaining ink amount determination unit that determines the remaining amount of ink in the tank based on the vertical position or tilt determined by the image analysis unit.

[0008] A second aspect of the present invention is the ink jet recording apparatus of the first aspect of the present invention, wherein the tank has a front surface, a back surface, and two side surfaces; the support mechanism is configured to support the tank so that the lower edges of the two side surfaces are tilted relative to the horizontal direction in accordance with the weight of the tank; the imaging unit is positioned so as to be able to image the front surface, the back surface, and one of the two side surfaces; the image analysis unit extracts a specific pattern in an image represented by the imaging data based on the imaging data, and determines the tilt based on the extracted specific pattern; and the remaining ink amount determination unit determines the remaining ink amount based on the tilt determined by the image analysis unit.

[0009] A third aspect of the present invention is the device according to the second aspect of the present invention, wherein the imaging unit is disposed at a position capable of imaging one of the front surface and the back surface, a label is affixed to the one surface, the specific pattern is two linear patterns indicating an upper end and a lower end of the label, and the image analysis unit calculates a distance between the two linear patterns in an image represented by the imaging data and calculates the inclination based on the distance.

[0010] A fourth aspect of the present invention is related to the second aspect of the present invention, wherein the imaging unit is positioned at a position where it can image one of the two side surfaces, the specific pattern is a linear pattern indicating a lower edge of the one surface, and the image analysis unit determines, as the tilt, an angle that the linear pattern makes with respect to a horizontal direction in an image represented by the imaging data.

[0011] A fifth aspect of the present invention is the second aspect of the present invention, wherein the imaging unit is arranged at a position where it can image one of the front and back surfaces, a mark including two indicators spaced apart in the vertical direction is affixed to the one of the front and back surfaces, the specific pattern is a pattern indicating the two indicators, and the image analysis unit determines the distance between the two indicators in an image represented by the imaging data and determines the tilt based on the distance.

[0012] A sixth aspect of the present invention is based on the first aspect of the present invention, wherein the support mechanism supports the tank such that the tank does not tilt and the vertical position of the tank changes according to the weight of the tank; the tank has a front, a back and two side faces; the imaging unit is positioned so as to be able to image the front, the back and one of the two side faces; the image analysis unit extracts a specific pattern in an image represented by the imaging data based on the imaging data and determines the vertical position of the extracted specific pattern; and the remaining ink amount determination unit determines the remaining ink amount based on the vertical position of the specific pattern determined by the image analysis unit.

[0013] In a seventh aspect of the present invention, based on the sixth aspect of the present invention, the specific pattern is a linear pattern indicating an upper side or a lower side of the one surface.

[0014] In an eighth aspect of the present invention, in the sixth aspect of the present invention, a label is attached to the one surface, and the specific pattern is a linear pattern indicating an upper end or a lower end of the label.

[0015] A ninth aspect of the present invention is the sixth aspect of the present invention, wherein a mark including an index is affixed to the one surface, the specific pattern is a pattern indicating the index, the image analysis unit determines a vertical position of the index in an image represented by the imaging data, and the remaining ink amount determination unit determines the remaining ink amount based on the vertical position of the index determined by the image analysis unit.

[0016] A tenth aspect of the present invention is the label according to the third or eighth aspect of the present invention, wherein the label includes a QR code (registered trademark) that records ink information, and the image analysis unit acquires the ink information from the imaging data.

[0017] An eleventh aspect of the present invention is the ink jet recording device according to the fifth or ninth aspect of the present invention, wherein the mark is a QR code that records ink information related to ink stored in the tank to which the mark is attached, and the image analysis unit acquires the ink information from the imaging data.

[0018] A twelfth aspect of the present invention is an inkjet printing device comprising: a transport mechanism that transports a long recording medium; a recording head that ejects ink onto the recording medium; a print execution control unit that controls the recording head and the transport mechanism so that a print image is formed on the recording medium; and an ink supply device according to any one of the first to eighth aspects that supplies ink to be ejected by the recording head.

[0019] A thirteenth aspect of the present invention is an ink supply method for supplying ink from a tank that stores ink in an ink supply device, comprising: an ink remaining amount detection step of detecting a remaining amount of ink in the tank, wherein the ink supply device includes: a support mechanism that includes an elastic member that supports a bottom surface of the tank, and supports the tank such that a vertical position or inclination of the tank changes according to a weight of the tank; and an imaging unit that images the tank, wherein the ink remaining amount detection step includes: an imaging step of imaging the tank with the imaging unit and generating imaging data that shows at least a part of the tank; an image analysis step of determining the vertical position or the inclination based on the imaging data; and a remaining ink amount determination step of determining the remaining amount of ink in the tank based on the vertical position or the inclination determined by the image analysis step.

[0020] Other aspects of the present invention will be apparent from the above aspects of the present invention and the following description of the embodiments and their modifications, and therefore will not be described here.

[0021] In a first aspect of the present invention, a tank support mechanism that supports a tank that stores ink is configured so that the vertical position or tilt of the tank changes depending on the weight of the tank, and the vertical position or tilt of the tank is determined by an image analysis unit based on image data of the tank, and the remaining ink amount in the ink tank is determined based on the determined vertical position or tilt. This requires lower maintenance costs than a configuration that uses a float to detect the remaining ink amount, and provides higher accuracy in detecting the remaining ink amount than a configuration that calculates the remaining ink amount based on the operating time of a pump that supplies ink. In this way, according to the first aspect of the present invention, the remaining ink amount in a tank that stores ink in an ink supply device can be accurately detected with a simple configuration that requires low maintenance costs. In addition, in cases where a label including a QR code that records ink information is attached to the outer surface of a tank and an imaging unit that images the label to obtain the ink information is already provided in the ink supply device, as in the tenth aspect of the present invention, or where a QR code that records ink information is attached to the tank and an imaging unit that images the QR code to obtain the ink information is already provided in the ink supply device, as in the eleventh aspect of the present invention, the remaining ink level can be detected simply by adding software for image analysis based on the image data captured by the imaging unit, thereby making it possible to detect the remaining ink level at lower cost.

[0022] The second to twelfth aspects of the present invention also provide the same effects as the first aspect of the present invention. In addition, the fourth aspect and the sixth to ninth aspects of the present invention also provide the following unique effects.

[0023] In other words, in a fourth aspect of the present invention, an imaging unit is positioned so as to be able to image the side of a tank attached to a tank support mechanism, and a linear pattern indicating the bottom edge of the side is extracted as a specific pattern from an image represented by imaging data generated by the imaging unit, and the angle that the linear pattern makes with the horizontal direction is determined as the inclination of the tank. In this way, the inclination of the tank can be directly determined based on imaging data obtained by imaging the tank from the side, making it possible to detect the remaining ink level with greater accuracy than in the second and third aspects of the present invention.

[0024] Furthermore, in the sixth to ninth aspects of the present invention, the tank support mechanism that supports the tank that stores ink is configured so that the vertical position of the tank can be changed according to the weight of the tank without the tank tilting. Therefore, even if the tank has a large capacity, ink can be supplied to the printing mechanism stably and safely while the remaining ink amount is detected, compared to the first to fifth aspects of the present invention.

[0025] The effects of other aspects of the present invention are clear from the explanation of the effects of the above aspects of the present invention and the effects of the following embodiment and its modifications, and therefore will not be explained here.

[0026] FIG. 1 is a schematic diagram showing the configuration of an inkjet printing apparatus according to a first embodiment of the present invention. FIG. 2 is a perspective view showing an outline of an ink supply mechanism in the first embodiment. FIG. 3 is a diagram showing the configuration of the ink supply apparatus in the first embodiment. FIG. 4 is a block diagram showing the hardware configuration of a control unit in the first embodiment. FIG. 5 is a block diagram showing the functional configuration of the control unit in the first embodiment. FIG. 6 is a diagram for explaining the configuration for detecting the remaining amount of ink in the first embodiment. FIG. 7 is a diagram showing the state of the ink supply apparatus when the remaining amount of ink is large in the first embodiment. FIG. 8 is a diagram showing the state of the ink supply apparatus when the remaining amount of ink is small in the first embodiment. FIG. 9 is a flowchart showing an example of the remaining ink amount detection process in the first embodiment. FIG. 10 is a flowchart showing another example of the remaining ink amount detection process in the first embodiment. FIG. 11 is a diagram for explaining image analysis in another example of the remaining ink amount detection process in the first embodiment. FIG. 12 is a diagram for explaining the configuration for detecting the remaining amount of ink in an ink supply apparatus in a modified example of the first embodiment. FIG. 13 is a diagram showing a captured image obtained in the modified example of the first embodiment. FIG. 14 is a flowchart showing an example of the remaining ink amount detection process in the modified example of the first embodiment. FIG. 10 is a diagram showing the state of the ink supply device when the remaining ink level is low in the second embodiment. FIG. 11 is a flowchart showing a first example of the remaining ink level detection process in the second embodiment. FIG. 12 is a flowchart showing a second example of the remaining ink level detection process in the second embodiment. FIG. 13 is a flowchart showing a third example of the remaining ink level detection process in the second embodiment. FIG. 14 is a diagram for explaining the advantages and disadvantages of the configuration for remaining ink level detection in the first embodiment, in comparison with other configurations for remaining ink level detection. FIG. 15 is a diagram for explaining the advantages and disadvantages of the configuration for remaining ink level detection in the second embodiment, in comparison with other configurations for remaining ink level detection.10A and 10B are diagrams for explaining advantages and disadvantages of the configuration for detecting the remaining amount of ink in the modified example of the first embodiment, in comparison with other configurations for detecting the remaining amount of ink.

[0027] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0028] 1 is a schematic diagram showing the configuration of an inkjet printing apparatus 10 according to a first embodiment of the present invention. The printing apparatus 10 includes a paper feed unit 202 that unwinds and supplies recording paper (hereinafter simply referred to as "paper") 5, which is a long continuous recording medium, from a roll of paper that is a roll-shaped recording medium, a first drive roller 203 that transports the paper 5 into a printing mechanism 200, a plurality of support rollers 204 that transport the paper 5 inside the printing mechanism 200, a recording unit 205 that prints by ejecting ink onto the paper 5, an ink supply mechanism 300 that supplies ink to the recording unit 205, a second drive roller 207 that outputs the paper 5 from inside the printing mechanism 200, and a paper take-up unit 208 that takes up the paper 5 after printing. The first drive roller 203, the support roller 204, and the second drive roller 207 form a transport mechanism for moving the paper 5. The recording unit 205 includes first to fourth recording heads 20C, 20M, 20Y, and 20K that eject C (cyan), M (magenta), Y (yellow), and K (black) inks, respectively, and first to fourth sub-tanks 22C, 22M, 22Y, and 22K that store the C, M, Y, and K inks, respectively, before ejection. The first to fourth recording heads 20C, 20M, 20Y, and 20K are connected to the first to fourth sub-tanks 22C, 22M, 22Y, and 22K by pipes, respectively. The ink supply mechanism 300 includes first to fourth ink supply devices 30C, 30M, 30Y, and 30K that supply C, M, Y, and K inks, respectively. The ink supplied from each ink supply device 30X is temporarily stored in a subtank 22X (X=C, M, Y, K) in the printing mechanism 200. Each recording head 20X ejects the ink stored in the subtank 22X (X=C, M, Y, K) according to the image to be printed, thereby forming the image as a color print image on the paper 5. The inkjet printing device 10 further includes a control unit 100 that controls each unit in the printing mechanism 200 and the ink supply mechanism 300. Details of the control unit 100 will be described later.

[0029] Conventionally, ink supply mechanisms have been known in which a label containing a QR code (registered trademark) recording ink information such as the composition of the ink stored in the ink tank (main tank), the manufacturing date, color, and model number is attached to the ink tank, and the ink information is acquired by reading the QR code with a camera. The ink supply mechanism 300 in this embodiment also has such a configuration. Figure 2 is a perspective view schematically showing the ink supply mechanism 300 in this embodiment. The main body 31 of this ink supply mechanism 300 is composed of a platform portion 31a having a horizontal upper surface and a wall portion 31b having a vertical front surface. As described above, the ink supply mechanism 300 includes the first to fourth ink supply devices 30C, 30M, 30Y, and 30K, and in these first to fourth ink supply devices 30C, 30M, 30Y, and 30K, the first to fourth ink tanks 32 that store C, M, Y, and K ink, respectively, are mounted on the platform portion 31a, and a tank support mechanism for these ink tanks is provided on the platform portion 31a (details will be described later).A QR code label recording ink information is affixed to the surface of the outer surface of each ink tank that faces the front surface of the wall portion 31b of the main body 31, i.e., the back surface, and a camera 41 for reading the QR code is built into the wall portion 31b.

[0030] 1.2 Ink Supply Device In the ink supply mechanism 300 of this embodiment, the first to fourth ink supply devices 30C, 30M, 30Y, and 30K, which supply C, M, Y, and K inks, respectively, have the same configuration and operate in the same manner, except for the color of ink they supply. Therefore, the following will focus on one of these four ink supply devices 30C, 30M, 30Y, and 30K and explain its configuration and operation (hereinafter, the ink supply device of interest will be designated by the reference symbol "30").

[0031] 3 is a block diagram showing the configuration of the ink supply device 30. The ink supply device 30 includes an ink tank 32, a tank support mechanism 330, a camera 41, a first liquid supply pipe 62, an intermediate tank 33, and a second liquid supply pipe 64. The ink tank 32 is also called a main tank. In the following, the upstream side of the ink supply path will be simply referred to as the "upstream side," and the downstream side of the ink supply path will be simply referred to as the "downstream side."

[0032] The tank support mechanism 330 is a base for supporting the ink tank 32 as an ink supply source, and is configured so that the ink tank 32 tilts (the bottom of the ink tank 32 tilts relative to the horizontal) depending on the amount of ink stored in the ink tank 32 (hereinafter also referred to as the "remaining ink amount"), i.e., depending on the weight of the ink tank 32. The ink tank 32 is a rectangular parallelepiped container, and a QR code (registered trademark) label 51 is attached to the back surface 32B of the ink tank 32 as a two-dimensional barcode recording ink information such as ink composition, manufacturing date, color, and model number. The camera 41 is an imaging unit provided for reading this QR code. The ink tank 32 stores unused ink. The initial ink storage capacity of the ink tank 32 is, for example, approximately 200 liters.

[0033] The first liquid supply pipe 62 is a pipe for supplying ink from the ink tank 32 to the intermediate tank 33. As shown in FIG. 3 , the first liquid supply pipe 62 has a suction pipe 321, a curved pipe 324, a descending pipe 322, and a main pipe 323. The suction pipe 321 sends ink from the ink tank 32 in an upward direction. The curved pipe 324 is connected to the downstream end (upper end) of the suction pipe 321 and changes the ink supply direction to a downward direction. The descending pipe 322 sends ink in a downward direction. The downstream end (lower end) of the descending pipe 322 is connected to the main pipe 323, which sends ink from the descending pipe 322 to the intermediate tank 33.

[0034] The suction pipe 321 is a pipe for sucking up ink from inside the ink tank 32. The suction pipe 321 has a suction port at its upstream end (lower end), and the suction port is located near the bottom surface inside the ink tank 32. Specifically, the upstream end of the suction pipe 321 abuts against the bottom surface inside the ink tank 32, and this end has a suction port that opens obliquely to the bottom surface of the ink tank 32.

[0035] The descending pipe 322 is a pipe located downstream of the curved pipe 324. The height of the descending pipe 322 gradually decreases toward the downstream side. In this embodiment, the descending pipe 322 extends downward in the vertical direction.

[0036] The main pipe 323 connects the downstream end of the descending pipe 232 and the intermediate tank 33. A solenoid valve 305 and a first pump 301 are interposed near the upstream end of the main pipe 323. The solenoid valve 305 switches between a closed state, in which the flow path in the pipe is closed, and an open state, in which the flow path in the pipe is open, in accordance with a control signal from the control unit 100. The first pump 301 creates a flow of ink toward the downstream side in the first liquid supply pipe 62. When the solenoid valve 305 is in the open state and the first pump 301 is operated, ink is supplied from the ink tank 32 through the suction pipe 321, the descending pipe 322, and the main pipe 323 to the intermediate tank 33.

[0037] The intermediate tank 33 is a tank that stores ink between the first liquid supply pipe 62 and the second liquid supply pipe 64. The capacity of the intermediate tank 33 is smaller than the capacity of the ink tank 32. For example, it is approximately 20 liters at most. The downstream end of the main pipe 323 is located inside the intermediate tank 33. The intermediate tank 33 temporarily stores ink and serves as a buffer that prevents ink from running out downstream of the intermediate tank 33.

[0038] First and second level sensors (not shown) are provided near the outside of the wall surface of the intermediate tank 33. The first level sensor 231 is a sensor that detects the presence or absence of ink at a predetermined lower limit position of the intermediate tank 23. Based on the detection results of the first and second level sensors, the control unit 100 determines whether the amount of ink stored in the intermediate tank 33 is within an allowable range.

[0039] The second liquid supply pipe 64 is a pipe connecting the intermediate tank 33 and the subtank 22 (the subtank 22C, 22M, 22Y, or 22K that is connected to the ink supply device 30 in question) in the printing mechanism 200. The upstream end of the second liquid supply pipe 24 is located near the bottom surface of the intermediate tank 33. The downstream end of the second liquid supply pipe 64 is connected to the subtank 22. A second pump 302 is also inserted in the path of the second liquid supply pipe 64. The second pump 302 creates a flow of ink in the second liquid supply pipe 64 toward the downstream side. When the second pump 302 is driven, ink stored in the intermediate tank 33 is supplied to the subtank 22 through the second liquid supply pipe 64.

[0040] 1.3 Configuration of the Control Unit FIG. 4 is a block diagram showing the hardware configuration of the control unit 100 in this embodiment. The control unit 100 includes a main body 11, an auxiliary storage device 12, a display unit 14, and an operation unit 15. The main body 11 includes a CPU 111, a memory 112, a disk interface unit 113, a display control unit 115, an input interface unit 116, a print execution control interface unit 117, an ink supply control interface unit 118, an imaging interface unit 119, and a network interface unit 120. The CPU 111, the memory 112, the disk interface unit 113, the display control unit 115, the input interface unit 116, the print execution control interface unit 117, the ink supply control interface unit 118, the imaging interface unit 119, and the network interface unit 120 are connected to one another via a system bus. The auxiliary storage device 12 is connected to the disk interface unit 113. The display unit 14 is connected to the display control unit 115. The operation unit 15, which includes a keyboard, a mouse, etc., is connected to the input interface unit 116. A network 3 is connected to the network interface unit 120, and the control unit 100 is connected to a host device or the like via this network 3. The auxiliary storage device 12 is a magnetic disk device or the like. The display unit 14 is a liquid crystal display or the like. The display unit 14 is used to display information desired by an operator. The operation unit 15 is used to input instruction operation information Iop that indicates instructions from the operator to the inkjet printing device 10.

[0041] The auxiliary storage device 12 stores a print control program 17 for generating print data from submitted data received via the network 3 and for causing the printing mechanism 200 to print an image represented by the print data. This print control program includes an ink supply control program for controlling the supply of ink to the printing mechanism 200, and an ink remaining amount detection program for detecting the amount of ink remaining in the ink tanks 32 in each of the ink supply devices 30C, 30M, 30Y, and 30K that supply the ink.

[0042] The CPU 111 reads the print control program 17 stored in the auxiliary storage device 12 into the memory 112 and executes it to realize various functions of the inkjet printing device 10. The memory 112 includes a RAM (Random Access Memory) and a ROM (Read Only Memory). The memory 112 functions as a work area for the CPU 111 to execute the print control program 17.

[0043] The print execution control interface unit 117 functions as an interface through which the CPU 111 executing the print control program controls each unit of the print mechanism 200. The image capture interface unit 119 functions as an interface through which the CPU 111 executing the print control program receives image capture data obtained by the camera 41 in each of the ink supply devices 30C, 30M, 30Y, and 30K capturing an image of the QR code or the like on the ink tank 32.

[0044] Figure 5 is a block diagram showing the functional configuration of the main functions of the control unit 100 in this embodiment. As described above, the CPU 111 executes the print control program 17 to realize the control unit 100 having the functional configuration shown in Figure 5. As shown in Figure 5, this control unit 100 functionally includes a print execution control unit 150, an ink supply control unit 152, an image analysis unit 162, and a remaining ink level determination unit 164, and the image analysis unit 162 and the remaining ink level determination unit 164 constitute a remaining ink level detection processing unit 160.

[0045] The print execution control unit 150 outputs control signals (hereinafter referred to as "print execution control signals") for controlling the print heads 20C, 20M, 20Y, and 20K and the drive rollers 203, 207 in the transport mechanism, etc., in accordance with instruction operation information Iop input based on operator operation via the operation unit 15. The ink supply control unit 152 receives information related to the control of the print heads 20C, 20M, 20Y, and 20K from the print execution control unit 110, and based on this information, outputs control signals (hereinafter referred to as "ink supply control signals") for controlling the pumps 301, 302 and solenoid valves 305 in each of the ink supply devices 30C, 30M, 30Y, and 30K. Based on the print execution control signal, the recording heads 20C, 20M, 20Y, 20K and drive rollers 203, 207, etc. in the printing mechanism 200 operate, and based on the ink supply control signal, the pumps 301, 302 and solenoid valve 305 in the ink supply devices 30C, 30M, 30Y, 30K operate, causing ink to be ejected from each recording head 20C, 20M, 20Y, 20K onto the transferred paper 5, and a color image based on the instruction operation information Iop is formed on the paper 5 as a printed image.

[0046] In parallel with this control of the printing mechanism 200 and the ink supply mechanism 300 (ink supply devices 30C, 30M, 30Y, and 30K), the remaining ink level detection processing unit 160 receives image data Dim obtained by capturing images of the aforementioned QR code labels 51 and the like using the cameras 41 in each of the ink supply devices 30C, 30M, 30Y, and 30K. In the remaining ink level detection processing unit 160, the image analysis unit 162 performs image analysis, described below, on the image represented by this image data Dim, and the remaining ink level determination unit 164 determines the amount of ink remaining in the ink tank 32 based on the results of this image analysis. The remaining ink amount determined in this manner is sent to the print execution control unit 150.

[0047] When the print execution control unit 150 receives the remaining ink amount from the remaining ink amount determination unit 164, it controls the display unit 14, the printing mechanism 200, and / or the ink supply mechanism 300 based on that remaining ink amount. For example, it displays the remaining ink amount on the display unit 14 in response to instruction operation information Iop that instructs display of the remaining ink amount, and if the remaining ink amount is below a predetermined amount, it displays warning information or information urging the user to replenish ink on the display unit 14, or stops the operation of the printing mechanism 200 and the ink supply mechanism 300.

[0048] The camera 41 is originally provided to read the QR code on the ink tank 32 and obtain ink information (such as ink composition, production date, color, and model number). Therefore, the image analysis unit 162 has the function of receiving imaging data Dim representing a captured image including an image of the QR code from the camera 41, obtaining ink information from the imaging data Dim, and sending the ink information to the print execution control unit 150. This makes it possible to prevent the use of inappropriate ink.

[0049] 1.4 Configuration and Operation for Detecting Remaining Ink Amount Next, the configuration and operation for detecting the remaining ink amount (hereinafter simply referred to as "remaining ink amount") in the ink tank 32 provided in each of the four ink supply devices 30C, 30M, 30Y, and 30K in this embodiment will be described, focusing on one ink supply device 30 of these four ink supply devices 30C, 30M, 30Y, and 30K (see FIG. 3). Note that hereinafter, the portions of the main body 31, its platform portion 31a, and its wall portion 31b (see FIG. 2) of the ink supply mechanism 300 that correspond to the ink supply device 30 of interest will also be referred to as the "main body 31," the "platform portion 31a," and the "wall portion 31b."

[0050] FIG. 6 is a diagram illustrating the configuration for detecting the remaining ink level in this embodiment. In the ink supply device 30 of this embodiment, the main body 31 has a platform portion 31a with a horizontal upper surface and a wall portion 31b with a vertical front surface. A plate-like member 331 is attached to the platform portion 31a of the main body 31, and is rotatable about a pivot 331a fixed to the top surface of the platform portion 31a. The pivot 331a is positioned so that it is parallel to the front surface of the wall portion 51b of the main body 31. The ink tank 32 is mounted such that its bottom surface is fixed to the top surface of the plate-like member 331 by a mounting member (not shown). When the ink tank 32 is mounted on the plate-like member 331, the pivot 331a is parallel to the lower edge of the rear surface 32B of the ink tank 32. An elastic member 332 is interposed between this plate-like member 331 and the platform portion 31a of the main body 31, and the plate-like member 331, the platform portion 31a, and the elastic member 332 form a tank support mechanism 330 for the ink tank 32. In this way, the tank support mechanism 330 supports the ink tank 32 attached to the plate-like member 331 with the elastic member 332, and is configured so that (the bottom surface of) the ink tank 32 tilts relative to the horizontal plane in accordance with the weight of the ink tank 32.

[0051] In the example shown in Fig. 6, the elastic member 332 interposed between the plate-like member 331 and the platform portion 31a of the main body 31 is a spring, but other elastic members such as a leaf spring may be used instead. Also, Fig. 6 shows the tank support mechanism 330 schematically, and the specific configuration of the tank support mechanism 330 (such as the number, shape, size, and arrangement of the elastic members 332) is appropriately designed to suit the purpose described below of detecting the remaining ink level based on the tilt of the ink tank 32 (the tilt of the plate-like member 331). In this embodiment, the ink tank 32 is an opaque container, but for convenience of explanation, Fig. 6 depicts the ink tank 32 as if it were a transparent container (the same applies to Figs. 6A to 19 described below).

[0052] 6, a QR code label 51 recording ink information (ink ingredients, production date, color, model number, etc.) is affixed to the surface of the rectangular parallelepiped container serving as the ink tank 32 that faces the front surface of the wall portion 31b of the main body 31, i.e., the back surface 32B. A camera 41 for capturing an image of the label 51 is built into the wall portion 31b of the main body 31.

[0053] Fig. 7A shows the state of the ink supply device 30 when the remaining ink amount is large in this embodiment, and Fig. 7B shows the state of the ink supply device 30 when the remaining ink amount is small in this embodiment. When the amount of ink 35 stored in the ink tank 32 attached to the ink supply device 30 (remaining ink amount) is large, the weight of the ink tank 32 is large, and therefore, as shown in Fig. 7A, the inclination θ1 of the plate-like member 331 to which the bottom surface of the ink tank 32 is fixed relative to the horizontal plane (hereinafter simply referred to as the "inclination of the ink tank 32") is small. Fig. 7A also shows the captured image Im represented by the imaging data Dim obtained from the camera 41 at this time.

[0054] In contrast, when the amount of ink 35 stored in the ink tank 32 attached to the ink supply device 30 (remaining ink amount) is small, the weight of the ink tank 32 is small, and therefore the inclination θ2 of the ink tank 32 is large, as shown in Figure 7B. Figure 7B also shows the captured image Im represented by the image data Dim obtained from the camera 41 at this time.

[0055] As described above, the slope θ2 when the ink level is low is larger than the slope θ1 when the ink level is high. As described above, when the slope θ of the ink tank 32 varies, the vertical distance between the two predetermined patterns spaced apart in the vertical direction in the captured image Im varies accordingly. In other words, the vertical distance between the two predetermined patterns in the captured image Im varies depending on the ink level. For example, the vertical distance h2 between the top and bottom edges of the QR code label 51 in the captured image Im obtained when the ink level is low is smaller than the vertical distance h1 between the top and bottom edges of the QR code label 51 in the captured image Im obtained when the ink level is high. Therefore, the ink level can be estimated by calculating the vertical distance between the top and bottom edges of the QR code label 51 from the image data Dim obtained by the camera 41, which is provided to read the QR code containing ink information. However, the color of the label 51 must be different from the color of the outer surface of the ink tank 32.

[0056] Therefore, in the control unit 100 of this embodiment, the CPU 111 performs the following ink level detection process, thereby realizing in software the ink level detection processing unit 160 (see Figure 5) including the image analysis unit 162 and ink level determination unit 164 described above.

[0057] 8 is a flowchart showing an example of the remaining ink amount detection process in this embodiment. In this remaining ink amount detection process, the CPU 111 operates as follows.

[0058] First, image data Dim generated by capturing an image of the QR code label 51 is received from the camera 41 (step S10). Next, based on this image data Dim, two linear patterns representing the top and bottom edges of the label 51 are extracted from the captured image (image represented by the image data Dim) Im (step S12), and the distance between the two extracted linear patterns is determined. Since the magnitude of this distance h corresponds to the magnitude of the inclination θ of the ink tank 32, the inclination θ of the ink tank 32 is determined based on this distance h (step S16). For example, a lookup table showing the relationship between this distance h and the inclination θ of the ink tank 32 is created in advance, and the inclination θ of the ink tank 32 is determined from the distance h between the two linear patterns by referencing this lookup table. Alternatively, instead of using such a lookup table, a mathematical formula showing this relationship may be calculated in advance. The remaining ink amount Aik is then determined based on the inclination θ of the ink tank 32 thus determined (step S18). Specifically, as with the above, a lookup table or formula showing the relationship between the tilt θ of the ink tank 32 and the remaining ink amount Aik is created in advance, and the remaining ink amount Aik is determined from the tilt θ using that lookup table or formula. Once the remaining ink amount Aik has been determined in this way, the remaining ink amount detection process ends.

[0059] Of the remaining ink amount detection process shown in FIG. 8, steps S10 to S16 implement the image analysis unit 162 shown in FIG. 5, and step S18 implements the remaining ink amount determination unit 164 shown in FIG.

[0060] Figure 9 is a flowchart showing another example of the remaining ink level detection process in this embodiment. While the remaining ink level detection process shown in Figure 8 calculates the inclination θ by focusing on the fact that the distance between the top and bottom sides of the QR code label 51 changes depending on the inclination θ of the ink tank 32, the remaining ink level detection process shown in Figure 9 calculates the inclination θ by focusing on the fact that the distance d (see Figure 10) between two cut-out symbols (finder patterns) spaced apart in the vertical direction, which serve as indicators included in the QR code, changes depending on the inclination θ of the ink tank 32. In this (another example) remaining ink level detection process, the CPU 111 operates as follows.

[0061] First, similar to step S10 shown in FIG. 8 , image data Dim generated by capturing an image of the QR code label 51 is received from the camera 41 (step S20). Next, based on this image data Dim, two cut-out symbols separated vertically from each other are extracted from the cut-out symbols included in the QR code in the captured image Im (step S22), and the distance d between the two extracted cut-out symbols is determined. Since the size of this distance d corresponds to the inclination θ of the ink tank 32, the inclination θ of the ink tank 32 is determined based on this distance d (step S26). Then, similar to step S18 shown in FIG. 8 , the remaining ink amount Aik is determined based on the determined inclination θ of the ink tank 32 (step S28), and the remaining ink amount detection process ends.

[0062] Of the remaining ink amount detection process shown in FIG. 9, steps S20 to S26 implement the image analysis unit 162 shown in FIG. 5, and step S28 implements the remaining ink amount determination unit 164 shown in FIG.

[0063] 7A and 7B , in the ink supply device 30 of this embodiment, the tank support mechanism 330 is configured so that the ink tank 32 tilts in accordance with the weight of the ink tank 32 (so that the plate-like member 331 to which the bottom surface of the ink tank 32 is fixed tilts with respect to the horizontal plane). The tilt θ of the ink tank 32 is determined using a camera 41 provided to read the QR code attached to the ink tank 32 and acquire ink information (see FIGS. 6, 8, and 9). That is, image analysis is performed on the captured image Im based on the imaging data Dim generated by the camera 41, and the vertical distance between two predetermined patterns (the distance h between the top and bottom sides of the label 51 or the vertical distance d between two cut-out symbols in the QR code) is determined as a result of the analysis, and the tilt θ of the ink tank 32 is determined based on this distance. In this way, by using the camera 41 that captures an image of the QR code label 51 and software processing such as image analysis based on the image data Dim, the remaining ink level can be detected with lower maintenance costs than when a float is used in the ink tank, and with higher accuracy than when using a method that relies on the operating time of a pump for supplying ink. Moreover, in an inkjet printing device equipped with a camera that captures an image of the QR code label affixed to the ink tank to obtain ink information, the image data from the camera can be used to detect the remaining ink level, so the remaining ink level can be detected simply by adding software for the remaining ink level detection process shown in Figure 8 or Figure 9. Therefore, according to this embodiment, the remaining ink level in a tank that stores ink in an ink supply device can be accurately detected with a simple configuration that requires low maintenance costs.

[0064] 1.6 Modifications In the first embodiment, the tilt θ of the ink tank 32 is calculated from the vertical distance between two predetermined patterns in the captured image Im based on the image data Dim of the QR code label 51 affixed to the rear surface 32B of the ink tank 32, and the remaining ink amount Aik is determined based on this tilt θ (see FIGS. 7A, 7B, 8, and 9). To improve the accuracy of detecting the remaining ink amount compared to the first embodiment, it is possible to position the camera 41 facing a side surface of the ink tank 32 rather than the rear surface 32B, so as to obtain an image that directly shows the tilt θ of the ink tank 32. Below, an inkjet supply device equipped with an ink supply device 30 configured in this manner will be described as a modification of the first embodiment. Note that the hardware configuration, except for the position of the camera 41 and the position of the QR code label 51, is the same as in the first embodiment, and the functional configuration of the control unit 100 is also the same as in the first embodiment (see FIG. 5). Therefore, the same or corresponding parts are designated by the same reference numerals, and detailed description thereof will be omitted. The remaining ink amount detection process in this modified example differs from the remaining ink amount detection process (FIGS. 8 and 9) in the first embodiment, and will be described later.

[0065] Fig. 11A is a diagram illustrating the configuration for detecting the remaining ink amount in the ink supply device 30 in this modified example. Fig. 11B is a diagram illustrating a captured image Im obtained in this modified example. Unlike the first embodiment in which a QR code label was affixed to the back surface 32B of the ink tank 32 as shown in Fig. 6, in this modified example, a QR code label 51 is affixed to the side surface of the ink tank 32 as shown in Fig. 11A. The camera 41 in this modified example is positioned so that it faces the side surface to which the QR code label 51 is affixed, i.e., so that the imaging direction of the camera 41 is perpendicular to that side surface (see Fig. 20 described below).

[0066] In this configuration, the camera 41 obtains a captured image Im as shown in Fig. 11B. The captured image data Dim (image data representing the captured image Im) generated by the camera 41 is sent to the control unit 100, and the CPU 111 performs the remaining ink level detection process shown in Fig. 12, thereby realizing in software the remaining ink level detection processing unit 160 including the image analysis unit 162 and remaining ink level determination unit 164 shown in Fig. 5.

[0067] 12 is a flowchart showing an example of the remaining ink amount detection process in this modified example. In this remaining ink amount detection process, the CPU 111 operates as follows.

[0068] First, image data Dim generated by capturing an image of the QR code label 51 on the side of the ink tank 32 is received from the camera 41 (step S30). Next, based on this image data Dim, a linear pattern representing the bottom edge of the side of the ink tank 32 is extracted from the captured image Im (step S32), and the inclination of the extracted linear pattern relative to the horizontal is determined as the inclination θ of the ink tank 32 (step S34). For example, in the captured image Im, in addition to the linear pattern representing the bottom edge of the side of the ink tank 32, a linear pattern representing the horizontal upper surface of the platform portion 31a of the main body 31 is extracted, and the angle between these two linear patterns is determined as the inclination θ of the ink tank 32. Next, the remaining ink amount Aik is determined based on the inclination θ of the ink tank 32 thus determined (step S36), and the ink remaining amount detection process ends.

[0069] Of the remaining ink amount detection process shown in FIG. 12, steps S30 to S34 implement the image analysis unit 162 shown in FIG. 5, and step S36 implements the remaining ink amount determination unit 164 shown in FIG. 5.

[0070] According to this modified example, as in the first embodiment, the tilt θ of the ink tank 32 is obtained using a camera 41 provided to read the QR code attached to the ink tank 32 and acquire ink information, and the remaining ink amount Aik is determined based on this tilt θ, thereby achieving the same effects as the first embodiment. Furthermore, according to this modified example, the tilt θ of the ink tank 32 is obtained directly from the image data Dim ( FIGS. 11 and 12 ), so the remaining ink amount can be detected with higher accuracy than in the first embodiment. Meanwhile, in this modified example, because the camera 41 is located on the side of the ink tank 32 ( FIGS. 11 and 20 ), a larger space is required in the lateral direction of the ink tank 32 compared to the first embodiment ( FIG. 6 ) in which the camera 41 was built into the main body 31 of the ink supply device 30.

[0071] 2. Second Embodiment In the first embodiment, as shown in FIGS. 7A and 7B , the tank support mechanism 330 is configured to tilt the ink tank 32 depending on the weight of the ink tank 32 it supports. However, if the ink tank 32 has a large capacity (e.g., a capacity exceeding 200 liters), it is preferable to avoid a configuration that tilts the ink tank 32 from the standpoint of stability and safety. Therefore, in an inkjet printing apparatus according to a second embodiment, the tank support mechanism 330 is configured to change the vertical position of the ink tank 32 without tilting depending on the weight of the ink tank 32 it supports. This second embodiment will be described below. Note that the hardware configuration of this embodiment, excluding the tank support mechanism 330, is similar to that of the first embodiment, and the functional configuration of the control unit 100 is also essentially similar to that of the first embodiment (see FIG. 5 ). Therefore, identical or corresponding parts are designated by the same reference numerals, and detailed description thereof will be omitted. The specific content of the remaining ink level detection process in this embodiment differs from the remaining ink level detection process in the first embodiment ( FIGS. 8 and 9 ), and will be described later.

[0072] <2.1 Configuration and operation for detecting remaining ink amount> Below, the configuration and operation for detecting the remaining ink amount in the ink tank 32 provided in each of the four ink supply devices 30C, 30M, 30Y, and 30K in this embodiment will be explained, focusing on one ink supply device 30 out of these four ink supply devices 30C, 30M, 30Y, and 30K (see Figure 3).

[0073] FIG. 13 is a diagram illustrating the configuration for detecting the remaining ink level in this embodiment. In the ink supply device 30 of this embodiment, the main body 31 has, as in the first embodiment, a platform portion 31a with a horizontal upper surface and a wall portion 31b with a vertical front surface. A plate-like member 331 is attached to the top surface of the platform portion 31a of the main body 31 via an elastic member 332. The ink tank 32 is attached so that its bottom surface is fixed to the top surface of the plate-like member 331 by a member (not shown). This plate-like member 331 is configured so that, when the ink tank 32 is attached thereto, the rear surface 32B of the ink tank 32 is parallel to the front surface of the wall portion 31b of the main body 31. The plate-like member 331, the platform portion 31a of the main body 31, and the elastic member 332 constitute a support mechanism 330 for the ink tank 32. In this way, the tank support mechanism 330 supports the ink tank 32 attached to the plate-like member 331 with the elastic member 332, and is configured so that the vertical position of the ink tank 32 changes depending on the weight of the ink tank 32.

[0074] 13, the elastic member interposed between the plate-like member 331 and the platform portion 31a of the main body 31 is a spring 332, but other elastic members such as a leaf spring may be used instead. Also, in FIG. 13, the tank support mechanism 330 is shown schematically, and the specific configuration of the tank support mechanism 330 (the number, shape, size, arrangement, etc. of the elastic members 332) is designed appropriately to suit the purpose of detecting the remaining ink amount based on the vertical position of the ink tank 32.

[0075] 13 , in this embodiment, as in the first embodiment, a QR code label 51 recording ink information (such as ink ingredients, production date, color, and model number) is affixed to the back surface 32B of the rectangular parallelepiped container serving as the ink tank 32. A camera 41 for capturing an image of this label 51 is built into the wall portion 31b of the main body 31.

[0076] Figure 14A shows the state of the ink supply device 30 when the remaining ink amount is large in this embodiment, and Figure 14B shows the state of the ink supply device 30 when the remaining ink amount is small in this embodiment. When the amount of ink 35 stored in the ink tank 32 attached to the ink supply device 30 (remaining ink amount) is large, the weight of the ink tank 32 is large, and therefore the vertical position of the ink tank 32 is low, as shown in Figure 14A. Figure 14A also shows the captured image Im represented by the imaging data Dim obtained from the camera 41 at this time.

[0077] In contrast, when the amount of ink 35 stored in the ink tank 32 attached to the ink supply device 30 (remaining ink amount) is small, the weight of the ink tank 32 is small, and therefore the vertical position of the ink tank 32 is high, as shown in Fig. 14B. Fig. 14B also shows the captured image Im represented by the image data Dim obtained from the camera 41 at this time.

[0078] As described above, the vertical position of the ink tank 32 changes depending on the amount of remaining ink, and the lower the amount of remaining ink, the higher the vertical position. Such changes in the vertical position of the ink tank 32 can be obtained from the image Im captured by the camera 41. Therefore, position information indicating the vertical position of the ink tank 32 in the captured image Im can be obtained based on the image data Dim, and the amount of remaining ink can be estimated from that position information.

[0079] Therefore, in the control unit 100 of this embodiment, the CPU 111 performs the ink level detection process described below, thereby realizing the ink level detection processing unit 160, which includes the image analysis unit 162 and ink level determination unit 164 described above, in software.

[0080] 15 is a flowchart showing a first example of the remaining ink amount detection process in this embodiment. In this remaining ink amount detection process, the CPU 111 operates as follows.

[0081] First, as in the first embodiment, image data Dim generated by capturing an image of the QR code label 51 is received from the camera 41 (step S40). Next, based on this image data Dim, a linear pattern representing the upper edge of the rear surface 32B of the ink tank 32 is extracted from the captured image Im (step S42), and the vertical position of the extracted linear pattern is determined. Here, the distance h from the bottom edge of the captured image Im to the linear pattern (hereinafter referred to as the "tank upper end position") is determined, and this is used as position information representing the vertical position of the upper edge of the rear surface 32B of the ink tank 32. Note that in Figures 14A and 14B, the hatched area in the captured image Im represents the outer surface (the rear surface 32B) of the ink tank 32. The tank upper end position h1 in the captured image Im when the ink level is high (shown in Figure 14A) is lower than the tank upper end position h2 in the captured image Im when the ink level is low (shown in Figure 14B).

[0082] In this way, the tank top position h in the captured image Im is determined as position information indicating the vertical position of the ink tank 32, and then the remaining ink amount Aik is determined based on this tank top position h. For example, a lookup table showing the relationship between this tank top position h and the remaining ink amount Aik can be created in advance, and the remaining ink amount Aik can be determined from the tank top position h in the captured image Im by referencing this lookup table. Alternatively, instead of using such a lookup table, a mathematical formula showing this relationship can be determined in advance. Once the remaining ink amount Aik has been determined in this way, the remaining ink amount detection process ends.

[0083] Of the remaining ink amount detection process shown in FIG. 15, steps S40 to S44 implement the image analysis unit 162 shown in FIG. 5, and step S46 implements the remaining ink amount determination unit 164 shown in FIG.

[0084] Figure 16 is a flowchart showing a second example of the remaining ink level detection process in this embodiment. In the first example of the remaining ink level detection process shown in Figure 15, the tank upper end position h in the captured image Im was obtained as position information indicating the vertical position of the ink tank 32, whereas in the second example, the height of the linear pattern indicating the top end of the QR code label 51 in the captured image Im is obtained as position information indicating the vertical position of the ink tank 32. In this second example of remaining ink level processing, the CPU 111 operates as follows.

[0085] First, similar to step S10 shown in FIG. 8 , image data Dim generated by capturing an image of the QR code label 51 is received from the camera 41 (step S50). Next, based on this image data Dim, a linear pattern representing the top edge of the QR code label 51 is extracted from the captured image Im (step S52), and the vertical position of the extracted linear pattern is determined. Here, the distance from the bottom edge of the captured image Im to the linear pattern (hereinafter referred to as the "label top edge position") is determined, and this is used as position information representing the vertical position of the ink tank 32. Note that instead of determining the label top edge position, the distance from the bottom edge of the captured image Im to the linear pattern representing the bottom edge of the QR code label 51 (hereinafter referred to as the "label bottom edge position") may also be determined.

[0086] In this way, the position of the top edge of the label in the captured image Im is determined as position information indicating the vertical position of the ink tank 32, and then the remaining ink amount Aik is determined based on this position of the top edge of the label. For example, a lookup table showing the relationship between this position of the top edge of the label and the remaining ink amount Aik is created in advance, and the remaining ink amount Aik is determined from the position of the top edge of the label in the captured image Im by referencing this lookup table. Alternatively, instead of using such a lookup table, a mathematical formula showing this relationship may be determined in advance. Once the remaining ink amount Aik has been determined in this way, the remaining ink amount detection process ends.

[0087] Of the remaining ink amount detection process shown in FIG. 16, steps S50 to S54 implement the image analysis unit 162 shown in FIG. 5, and step S56 implements the remaining ink amount determination unit 164 shown in FIG.

[0088] 17 is a flowchart showing a third example of the remaining ink level detection process in this embodiment. In this third example, a predetermined cut-out symbol contained in a QR code is extracted from the captured image Im, and the vertical position of this cut-out symbol is obtained as position information indicating the vertical position of the ink tank 32. In this third example of remaining ink level processing, the CPU 111 operates as follows.

[0089] First, image data Dim generated by capturing an image of the QR code label 51 is received from the camera 41 (step S60). Next, based on this image data Dim, a specific cut-out symbol (e.g., the upper left cut-out symbol in the QR code shown in FIG. 10 ) is extracted from the cut-out symbols included in the QR code in the captured image Im (step S62), and the vertical position of the extracted cut-out symbol in the captured image Im is determined (step S64). Here, the distance from the bottom edge of the captured image Im to the cut-out symbol (hereinafter referred to as the "vertical position of the symbol") is determined, and this is used as position information indicating the vertical position of the ink tank 32.

[0090] In this way, the vertical position of the symbol in the captured image Im is determined as position information indicating the vertical position of the ink tank 32, and then the remaining ink amount Aik is determined based on this vertical position of the symbol. For example, a lookup table showing the relationship between this vertical position of the symbol and the remaining ink amount Aik is created in advance, and the remaining ink amount Aik is determined from the vertical position of the symbol in the captured image Im by referencing this lookup table. Alternatively, instead of using such a lookup table, a mathematical formula showing this relationship may be determined in advance. Once the remaining ink amount Aik has been determined in this way, the remaining ink amount detection process ends.

[0091] Of the remaining ink amount detection process shown in FIG. 17, steps S60 to S64 implement the image analysis unit 162 shown in FIG. 5, and step S66 implements the remaining ink amount determination unit 164 shown in FIG.

[0092] 2.2 Effects As described above, in this embodiment, the tank support mechanism 330 in the ink supply device 30 is configured so that the vertical position of the ink tank 32 changes depending on the weight of the ink tank 32, as shown in FIGS. 14A and 14B . The vertical position of the ink tank 32 is determined using a camera 41 that is provided to read the QR code attached to the ink tank 32 and acquire ink information (see FIGS. 13 and 15 to 17 ). That is, image analysis is performed on the captured image Im based on the image data Dim generated by the camera 41, and the vertical position of a predetermined linear pattern or a predetermined segmented symbol resulting from the analysis is determined. The remaining ink level is determined based on this vertical position (see FIGS. 15 to 17 ). In this manner, as in the first embodiment, the remaining ink level is detected using the camera 41 that captures the QR code label 51 and software processing, such as image analysis, based on the image data Dim. Therefore, according to this embodiment, as in the first embodiment, the remaining ink level in a tank that stores ink in the ink supply device can be accurately detected using a simple configuration with low maintenance costs.

[0093] In this embodiment, the tank support mechanism 330 is configured to change the vertical position of the ink tank 32 attached to the ink supply device 30 in accordance with its weight without tilting (FIGS. 14A and 14B). Therefore, compared to the first embodiment, even when using an ink tank 32 with a larger capacity, ink can be supplied to the printing mechanism 200 stably and safely while the remaining ink amount is detected.

[0094] 3. Advantages and Disadvantages of Configurations for Detecting Remaining Ink Amount> The following three configurations for detecting the remaining ink amount have been described above. The advantages and disadvantages of these three configurations will be described below. (1) Configuration 1: As shown in Fig. 18 , this configuration supports the ink tank 32 so that it tilts according to its weight, and the camera 41 is positioned so that the rear surface 32B of the ink tank 32 is imaged from the front of the device body 31. (2) Configuration 2: As shown in Fig. 19 , this configuration supports the ink tank 32 so that its vertical position changes according to its weight without tilting, and the camera 41 is positioned so that the rear surface 32B of the ink tank 32 is imaged from the front of the device body 31. (3) Configuration 3: As shown in Fig. 20 , this configuration supports the ink tank 32 so that it tilts according to its weight, and the camera 41 is positioned so that the side of the ink tank 32 is imaged. (Configuration used in the modified version of the first embodiment).

[0095] Configuration 1 is advantageous in that the ink tank is configured to tilt (rotate around pivot 331a) in accordance with its weight, thereby narrowing the range of movement of the ink tank. On the other hand, configuration 1 is disadvantageous in that the configuration of the tank support mechanism 330 is more complex than the tank support mechanism 330 in configuration 2. Also, configuration 1 is disadvantageous compared to configurations 2 and 3 in terms of the accuracy of detecting the remaining ink amount, because the tilt θ of the ink tank is calculated based on the distance between two patterns spaced apart in the vertical direction in the captured image Im, and the remaining ink amount Aik is determined based on this tilt.

[0096] Configuration 2 is advantageous in that the configuration of the tank support mechanism 330 is simpler than configuration 1 because the ink tank is configured to change its vertical position in accordance with its weight without tilting, and that even if the ink tank has a large capacity, it can detect the amount of remaining ink and stably and safely supply ink to the printing mechanism 200. On the other hand, configuration 2 is disadvantageous compared to configurations 1 and 2 in that the ink tank moves over a larger range depending on the amount of remaining ink, and the ink tank's mounting position on the tank support mechanism must be positioned with high precision.

[0097] Configuration 3 is advantageous over configuration 1 in that the ink tank is configured to tilt in accordance with its weight, and camera 41 is positioned so that the tilt θ of the ink tank is directly imaged from the side, allowing the remaining ink level to be detected with high accuracy. On the other hand, configuration 3 is disadvantageous in that camera 41 is not built into device main body 31 but is positioned to face the side of the ink tank, requiring space to the side of the ink tank, making ink supply device 30 larger than configurations 1 and 3.

[0098] 4. Modifications The present invention is not limited to the above-described embodiment and modifications, and various modifications can be made without departing from the scope of the present invention.

[0099] For example, in each of the above embodiments, a camera that captures an image of a label 51, such as a QR code, on which ink information is recorded (hereinafter referred to as an "ink information acquisition camera") is used as the imaging unit for detecting the amount of ink remaining in the ink tank 32. However, the present invention can also be applied to inkjet printing devices that do not have such an ink information acquisition camera by providing a camera for detecting the amount of ink remaining. Furthermore, inkjet printing devices that have such a camera for acquiring ink information may also have a separate camera for detecting the amount of ink remaining.

[0100] In addition, in each of the above embodiments, the camera 41 is positioned so as to face the back or side of the rectangular parallelepiped ink tank 32, but the camera may be positioned in another location (for example, facing the front of the ink tank 32) within the scope of the spirit of the present invention. However, in conjunction with a change in the camera position, the surface of the ink tank 32 to which the QR code label 51 is affixed should be changed as needed.

[0101] Furthermore, in each of the above embodiments, the camera 41 is positioned so as to capture an image of the QR code label 51, but the camera 41 may also be configured to capture an image of a label other than the QR code label 51 that has a color different from the color of the exterior surface of the ink tank 32. Furthermore, as in the first example ( FIG. 15 ) of the above second embodiment, in cases where the remaining ink amount is determined based on the vertical position of the ink tank 32 that is obtained based on a linear pattern that indicates the top end of the ink tank 32 (the upper side of the rear surface 32B) in the captured image Im, the camera 41 may be positioned so as to face the surface of the exterior surface of the ink tank 32 that does not have a label 51 such as a QR code attached.

[0102] In the above embodiments and modifications, the ink tank 32 is a rectangular parallelepiped container, but containers of other shapes (for example, cylindrical containers) may be used as long as they do not deviate from the spirit of the present invention. In the above embodiments and modifications, a label 51 including a QR code is affixed to the ink tank 32, but instead of the QR code, other two-dimensional barcodes, or more generally, other image codes that represent identification codes as images, may be used. Furthermore, instead of affixing a label 51 including a QR code to the ink tank 32, an image code such as a QR code may be recorded directly on the outer surface (back or side, etc.) of the ink tank 32.

[0103] DESCRIPTION OF SYMBOLS 5...Paper (recording medium) 10...Inkjet printing device 17...Printing control program 20C, 20M, 20Y, 20K...Recording head 22C, 22M, 22Y, 22K...Sub-tank 30C, 30M, 30Y, 30K...Ink supply device 32...Ink tank (main tank) 32B...Rear surface (of ink tank) 35...Ink 41...Camera (imaging unit) 51...QR code label 100...Control unit 111...CPU 150...Print execution control unit 152...Ink supply control unit 160...Remaining ink amount detection processing unit 162...Image analysis unit 164...Remaining ink amount determination unit 200...Printing mechanism 300...Ink supply mechanism 330...Tank support mechanism 332...Elastic member Dim...Im...Im...Im

Claims

1. An ink supply device comprising: a tank for storing ink; a support mechanism for supporting the tank, the support mechanism including an elastic member supporting a bottom surface of the tank, and supporting the tank such that the vertical position or inclination of the tank changes in accordance with the weight of the tank; an imaging unit for imaging the tank and generating imaging data showing at least a portion of the tank; an image analysis unit for determining the vertical position or inclination based on the imaging data; and an ink remaining amount determination unit for determining the amount of ink remaining in the tank based on the vertical position or inclination determined by the image analysis unit.

2. The ink supply device of claim 1, wherein the tank has a front, a back, and two side surfaces, the support mechanism is configured to support the tank so that the lower edges of the two side surfaces are inclined relative to the horizontal direction in accordance with the weight of the tank, the imaging unit is positioned to image the front, the back, and one of the two side surfaces, the image analysis unit extracts a specific pattern in an image represented by the imaging data based on the imaging data and determines the inclination based on the extracted specific pattern, and the ink remaining amount determination unit determines the ink remaining amount based on the inclination determined by the image analysis unit.

3. An ink supply device as described in claim 2, wherein the imaging unit is positioned at a position capable of imaging one of the front and back faces, a label is affixed to the one face, the specific pattern is two linear patterns indicating the upper and lower ends of the label, and the image analysis unit determines the distance between the two linear patterns in an image represented by the imaging data and determines the inclination based on the distance.

4. An ink supply device as described in claim 2, wherein the imaging unit is positioned at a position capable of imaging one of the two side surfaces, the specific pattern is a linear pattern indicating the bottom edge of the one surface, and the image analysis unit determines the inclination as the angle that the linear pattern makes with respect to the horizontal direction in the image represented by the imaging data.

5. An ink supply device as described in claim 2, wherein the imaging unit is positioned at a position where it can image one of the front and back faces, a mark including two indicators spaced apart in the vertical direction is affixed to the one of the front and back faces, the specific pattern is a pattern indicating the two indicators, and the image analysis unit determines the distance between the two indicators in an image represented by the imaging data and determines the inclination based on the distance.

6. An ink supply device as described in claim 5, wherein the mark is a QR code (registered trademark), and the two indicators are two cut-out symbols in the QR code that are spaced apart in the vertical direction.

7. An ink supply device as described in claim 2, wherein the support mechanism is provided on a plate-like member to which the bottom surface of the tank is fixed and includes a pivot shaft portion extending parallel to the lower edge of the back surface, the elastic member is positioned so as to support the bottom surface directly or via the plate-like member at a position spaced from the pivot shaft portion, and the support mechanism supports the tank so as to rotate around the pivot shaft portion in accordance with the weight of the tank.

8. The ink supply device of claim 1, wherein the support mechanism supports the tank so that the vertical position of the tank changes according to the weight of the tank without tilting the tank, the tank has a front, a back and two side surfaces, the imaging unit is positioned at a position where it can image the front, the back and one of the two side surfaces, the image analysis unit extracts a specific pattern in an image represented by the imaging data based on the imaging data and determines the vertical position of the extracted specific pattern, and the ink remaining amount determination unit determines the remaining ink amount based on the vertical position of the specific pattern determined by the image analysis unit.

9. The ink supply device according to claim 8, wherein the specific pattern is a linear pattern indicating an upper side or a lower side of the one surface.

10. The ink supply device according to claim 8, wherein a label is affixed to said one surface, and said specific pattern is a linear pattern indicating the upper end or the lower end of said label.

11. The ink supply device according to claim 8, wherein a mark including an index is affixed to the one surface, the specific pattern is a pattern showing the index, the image analysis unit determines a vertical position of the index in an image represented by the imaging data, and the remaining ink amount determination unit determines the remaining ink amount based on the vertical position of the index determined by the image analysis unit.

12. The ink supply device according to claim 11, wherein the mark is a QR code, and the indicator is a specific cut-out symbol among cut-out symbols included in the QR code.

13. An ink supply device as described in claim 3 or 10, wherein the label includes a QR code that records ink information, and the image analysis unit acquires the ink information from the imaging data.

14. An ink supply device as described in claim 5, 6, 11, or 12, wherein the mark is a QR code that records ink information regarding the ink stored in the tank to which the mark is attached, and the image analysis unit acquires the ink information from the imaging data.

15. An inkjet printing device comprising: a transport mechanism for transporting a long recording medium; a recording head for ejecting ink onto the recording medium; a print execution control unit for controlling the recording head and the transport mechanism so as to form a print image on the recording medium; and an ink supply device according to any one of claims 1 to 12 for supplying ink to be ejected by the recording head.

16. An ink supply method for supplying ink from a tank that stores ink in an ink supply device, comprising: an ink remaining amount detection step of detecting an amount of ink remaining in the tank, wherein the ink supply device comprises: a support mechanism that includes an elastic member supporting a bottom surface of the tank and supports the tank so that the vertical position or inclination of the tank changes depending on the weight of the tank; and an imaging unit that images the tank, wherein the ink remaining amount detection step comprises: an imaging step of imaging the tank with the imaging unit and generating imaging data showing at least a portion of the tank; an image analysis step of determining the vertical position or inclination based on the imaging data; and an ink remaining amount determination step of determining the amount of ink remaining in the tank based on the vertical position or inclination determined by the image analysis step.

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