Printing apparatus, printing method, and mark unit

Abstract

In a case where the size of a three-dimensional object is to be measured by detecting a mark provided on the outer peripheral surface of the three-dimensional object by a sensor, there is a concern that printing on the outer peripheral surface of the three-dimensional object may be hindered by the mark because the printing area is narrowed by the mark or the image quality of a printed image is impaired by the mark.SOLUTION: A printing apparatus according to the present disclosure includes a head that ejects ink, a rotation unit that rotates a cylindrical medium to be printed using the head, a sensor that detects a mark attached to the medium using an inner circumferential surface of the medium, and a controller that obtains a driving amount of the rotation unit from when the sensor detects the mark by rotating the medium to when the sensor detects the mark by further rotating the medium.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a printing device, a printing method, and a marking unit. [Background technology]

[0002] Patent Document 1 describes a printing system that prints an image on the side surface (outer peripheral surface) of a cylindrical three-dimensional object. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-100880 Summary of the Invention [Problem to be solved by the invention]

[0004] In the printing system described in Patent Document 1, a user inputs the size of a three-dimensional object to obtain information about the size of the three-dimensional object required for printing. However, there is a risk that the actual size of the three-dimensional object may differ from the size input by the user. Furthermore, when measuring the size of a three-dimensional object by detecting marks on the outer surface of the three-dimensional object with a sensor, the marks may narrow the printing area or impair the quality of the printed image, which may hinder printing on the outer surface of the three-dimensional object.

[0005] An object of the present invention is to measure the size of a cylindrical three-dimensional object without interfering with printing. [Means for solving the problem]

[0006] The main invention to achieve the above object is: a head that ejects ink; a rotation unit that rotates a cylindrical medium that is the target of printing using the head; a sensor that detects a mark attached to the medium by utilizing the inner peripheral surface of the medium; a controller that calculates the amount of drive of the rotation unit from when the sensor detects the mark while rotating the medium to when the sensor detects the mark while further rotating the medium; A printing device comprising:

[0007] Other features of the present invention will become apparent from the description of this specification. [Effects of the Invention]

[0008] According to the present invention, the size of a cylindrical three-dimensional object can be measured without interfering with printing. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is an explanatory diagram of a printing system 100. As shown in FIG. [Figure 2] 2A and 2B are explanatory diagrams of the printing device 1. FIG. [Figure 3] FIG. 3 is a block diagram of the printing system 100. [Figure 4] FIG. 4 is an explanatory diagram of the rotation unit 70. [Figure 5] FIG. 5 is an explanatory diagram of the state in which the cylindrical medium M2 is placed on the rotation unit 70. [Figure 6] 6A and 6B are explanatory diagrams of the mark unit 80. FIG. [Figure 7] Fig. 7A is an explanatory diagram of a displacement mechanism 84 of a first modified example, Fig. 7B is an explanatory diagram of a displacement mechanism 84 of a second modified example, and Fig. 7C is an explanatory diagram of a displacement mechanism 84 of a third modified example. [Figure 8] 8A and 8B are explanatory diagrams of a modified mark 80A. [Figure 9] FIG. 9 is a flow diagram of a printing method using the mark unit 80. [Figure 10] FIG. 10 is a flow diagram of the measurement process. [Figure 11]FIG. 11 is an explanatory diagram showing the relationship between the count value of the number of pulses of the encoder 75 and the output of the sensor 76 in the measurement process. [Figure 12] Fig. 12A is an explanatory diagram of a printed image indicated by the second command code, Fig. 12B is an explanatory diagram of a printed image printed on cylindrical medium M2 by the second command code, and Fig. 12C is an explanatory diagram of a printed image indicated by the second command code that causes printing device 1 to print multiple layers. [Figure 13] FIG. 13 is an explanatory diagram of the state during measurement processing in the modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] === Implementation form === <Printing system> Fig. 1 is an explanatory diagram of a printing system 100. Fig. 2A and Fig. 2B are explanatory diagrams of a printing device 1. Fig. 3 is a block diagram of the printing system 100.

[0011] In the following description, the direction in which the carriage 21 (or head 10) moves may be referred to as the "scanning direction" or "left-right direction." In the left-right direction, the right side as viewed from the operator operating the printing device 1 may be referred to as the "right," and the opposite side as the "left." The vertical direction may be referred to as the "up-down direction," with the upper side of the vertical direction referred to as the "upper," and the opposite side referred to as the "lower." The direction perpendicular to the scanning direction and the up-down direction may be referred to as the "front-to-rear direction." In the front-to-rear direction, the side of the operator operating the printing device 1 as viewed from the printing device 1 may be referred to as the "front," and the opposite side as the "rear." The table 31 can move along the front-to-rear direction. The front-to-rear direction may be referred to as the "transport direction" or "sub-scanning direction." The scanning direction may be referred to as the "first direction," the front-to-rear direction as the "second direction," and the up-to-down direction as the "third direction."

[0012] The printing system 100 is a system for printing on a medium (print substrate) to be printed on. While FIG. 1 shows printing on a plate-shaped medium M1, it is also possible to print on a cylindrical medium (cylindrical medium M2; described below). The printing system 100 comprises a printing device 1 and a print control device 90. However, the printing system 100 may be configured as a single printing device 1, with the printing device 1 fulfilling the functions of the print control device 90 (described below).

[0013] The printing device 1 is a device for printing on a medium. Here, the printing device 1 ejects ultraviolet curable ink (UV ink) onto the medium and irradiates the dots formed on the medium with ultraviolet light to cure the dots. In other words, the printing device 1 is a so-called UV printer. However, the ink ejected by the printing device 1 does not have to be UV ink.

[0014] The printing device 1 includes a head 10, a carriage unit 20, a transport unit 30, a lifting unit 40, an irradiation unit 50, and a controller 60. The printing device 1 can also be equipped with a rotation unit 70 as an option.

[0015] The head 10 is a member that ejects ink (here, UV ink) onto a medium. The head 10 is mounted on a carriage 21 and is movable in the scanning direction.

[0016] The carriage unit 20 is a unit that moves the carriage 21. The carriage unit 20 has the carriage 21, a carriage motor 22, and a guide 23. The carriage 21 is a member that moves back and forth along the scanning direction. The carriage 21 is equipped with the head 10 and the irradiation unit 50. The carriage motor 22 is a motor that moves the carriage 21. The carriage motor 22 moves the carriage 21 in the scanning direction via a transmission mechanism such as a pulley or belt. The guide 23 is a member that guides the carriage 21 in the scanning direction. The guide 23 is fixed to the base 1A (the main body of the printing device 1).

[0017] The transport unit 30 is a unit that transports a medium. The transport unit 30 has a table 31 and a transport motor 32. The table 31 is a member on which the medium is placed. The transport motor 32 is a motor that moves the table 31. The transport motor 32 moves the table 31 in the front-to-rear direction via a transmission mechanism (feed screw mechanism) such as a feed screw and a nut.

[0018] The lifting unit 40 is a unit that raises and lowers the table 31. The lifting unit 40 has a lifting member 41 and a lifting motor 42. The lifting member 41 is a member on which the transport unit 30 is placed and which is movable in the vertical direction. The lifting motor 42 is a motor for moving the lifting member 41 in the vertical direction. The lifting unit 40 moves the transport unit 30 in the vertical direction, thereby moving the medium placed on the table 31 in the vertical direction.

[0019] The irradiation unit 50 is a unit that irradiates the medium with ultraviolet light. The irradiation unit 50 has a light source 51 that emits ultraviolet light. The light source 51 is configured, for example, with an LED array in which a plurality of LEDs (UV-LEDs) are arranged. The irradiation unit 50 is mounted on the carriage 21. Therefore, the irradiation unit 50 can move along the scanning direction together with the carriage 21 (and the head 10). Note that if the head 10 ejects ink other than UV ink, the printing device 1 does not need to be equipped with the irradiation unit 50.

[0020] The controller 60 is a control unit that is responsible for controlling the printing device 1. The controller 60 controls each component of the printing device 1 (the head 10, the carriage unit 20 (more specifically, the carriage motor 22), the transport unit 30 (more specifically, the transport motor 32), the lifting unit 40 (more specifically, the lifting motor 42), and the irradiation unit 50 (more specifically, the light source 51). The controller 60 has an arithmetic processing unit and a storage device, not shown. The arithmetic processing unit is composed of, for example, a CPU, an MPU, etc. The storage device has, for example, RAM used to execute programs and ROM for storing programs. The printing process is carried out by the arithmetic processing unit executing the programs stored in the storage device.

[0021] The controller 60 includes a print processing unit 61 and a measurement processing unit 62 .

[0022] The print processing unit 61 prints on the medium. The print processing unit 61 prints an image on the medium by controlling each component of the printing device 1 in accordance with a command code received from the print control device 90. By controlling each component of the printing device 1, the print processing unit 61 can perform a print process (first print process) that prints an image on the medium M1 placed on the table 31 as shown in FIG. 1, and a print process (second print process) that prints an image on the outer peripheral surface of a cylindrical medium (cylindrical medium M2; described below) using a rotation unit 70 (described below).

[0023] The measurement processing unit 62 measures the size of a cylindrical medium (cylindrical medium M2; described later). The process of measuring the size of a cylindrical medium (measurement process) will be described later. In the following description, a cylindrical medium may be referred to as a "cylindrical medium."

[0024] The print control device 90 is a device that controls the printing device 1. The print control device 90 generates a command code for causing the printing device 1 to print an image, and transmits the command code to the printing device 1. The print control device 90 causes the printing device 1 to perform printing via the command code.

[0025] Here, the print control device 90 is configured as a general-purpose personal computer. The print control device 90 has, as hardware, an arithmetic processing unit and a storage device (not shown). The arithmetic processing unit is configured, for example, by a CPU. The storage device is configured, for example, by a main storage device such as RAM, and an auxiliary storage device such as a hard disk drive or SSD. Various functions are realized by the arithmetic processing unit executing programs stored in the storage device.

[0026] A display device 90A and an input device 90B are connected to the print control device 90. The print control device 90 can display various screens on the display device 90A. The print control device 90 can also acquire information input by the input device 90B. For example, the print control device 90 can display an input image for inputting the size, such as the outer diameter, of a cylindrical medium (described below), and acquire the numerical values ​​that the operator inputs into the input screen using the input device 90B. Note that, since there is a risk that the medium size input by the user may differ from the actual size, the print control device 90 can acquire data (size data) related to the size of the medium measured by the printing device 1 from the printing device 1, as described below.

[0027] The print control device 90 includes a first command code generating unit 91, a second command code generating unit 92, and a communication unit 93.

[0028] The first command code generation unit 91 generates a command code for the first printing process (a printing process for printing an image on a medium M1 placed on the table 31). In the first printing process, the printing device 1 alternately repeats a dot formation operation in which the head 10 ejects ink from the head 10 to form dots on the medium while driving the carriage unit 20 (carriage motor 22) to move the head 10 in the scanning direction, and the irradiation unit 50 (light source 51) irradiates ultraviolet light to harden the dots, and a transport operation in which the transport unit 30 (transport motor 32) is driven to transport the medium, thereby printing an image on the medium. The first command code generation unit 91 generates a command code for causing the printing device 1 to execute this first printing process.

[0029] The second command code generation unit 92 generates a command code for a second printing process (a printing process for printing an image on the outer peripheral surface of a cylindrical medium (cylindrical medium M2; described below)). In the second printing process, the printing device 1 alternately performs a dot formation operation (an operation for driving the carriage unit 20 to move the head 10 in the scanning direction while ejecting ink from the head 10 to form dots on the medium, and for curing the dots by irradiating ultraviolet light from the irradiation unit 50) and a rotation operation for rotating the cylindrical medium by a predetermined amount using the rotation unit 70, described below, to print an image on the outer peripheral surface of the cylindrical medium (in the second printing process, a rotation operation is performed instead of the transport operation of the first printing process). The second command code generation unit 92 generates a command code for causing the printing device 1 to execute this second printing process. The second printing process will be described later.

[0030] The communication unit 93 communicates with the printing device 1. The communication unit 93 transmits command codes to the printing device 1 and receives data from the printing device 1, for example.

[0031] <Rotating unit> Fig. 4 is an explanatory diagram of the rotation unit 70. Fig. 5 is an explanatory diagram of the state in which the cylindrical medium M2 is placed on the rotation unit 70.

[0032] A rotation unit 70 can be attached as an option to the printing device 1. The rotation unit 70 is a unit used when printing on the cylindrical medium M2. In other words, the rotation unit 70 is a unit used in the second printing process.

[0033] The cylindrical medium M2 is a cylindrical medium (printing substrate) to be printed on. The outer peripheral surface (side surface) of the cylindrical medium M2 becomes the printing surface for printing an image. The cylindrical medium M2 is configured in a hollow cylindrical shape. The cylindrical medium M2 is, for example, a cup, a pencil holder, a paper holder, etc., but may also be a member for other purposes. The cylindrical medium M2 is also made of, for example, paper or resin, but may also be made of other materials. The cylindrical medium M2 may also be a light-blocking material, a transparent material, or a translucent material.

[0034] As shown in FIG. 4, the rotation unit 70 can be fixed to the table 31. By moving the table 31 to which the rotation unit 70 is fixed in the front-rear and up-down directions, the rotation unit 70 can be moved in the front-rear and up-down directions. Also, as shown in FIG. 5, a cylindrical medium M2 can be placed on the rotation unit 70. This allows the cylindrical medium M2 to be moved in the front-rear and up-down directions by moving the table 31. Also, as shown in FIG. 5, the rotation unit 70 can rotate the cylindrical medium M2 around an axis along the scanning direction. Note that the rotation unit 70 does not have to be installed on the table 31, and may be installed, for example, on the lifting member 41 of the lifting unit 40.

[0035] The rotation unit 70 includes a frame 70A, a first rotation member 71, a second rotation member 72, a drive motor 73, a transmission mechanism 74, and an encoder 75.

[0036] The frame 70A is a member that forms the outer frame of the rotation unit 70. The frame 70A is placed on and fixed to the table 31. In FIG. 4, the frame 70A is fixed to the table 31 with screws, but the method of fixing the frame 70A to the table 31 is not limited to this. The frame 70A houses a first rotating member 71 and a second rotating member 72. The frame 70A rotatably supports the first rotating member 71 and the second rotating member 72. A portion of the top surface of the frame 70A is open, and the first rotating member 71 and the second rotating member 72 are exposed through this opening.

[0037] The first rotating member 71 and the second rotating member 72 are rotatable members. The first rotating member 71 and the second rotating member 72 are each rotatable around an axis along the scanning direction. The first rotating member 71 and the second rotating member 72 are arranged parallel to the scanning direction. The first rotating member 71 and the second rotating member 72 support the cylindrical medium M2. The cylindrical medium M2 can be rotated by the first rotating member 71 and the second rotating member 72 rotating while supporting the cylindrical medium M2.

[0038] The first rotating member 71 has a first shaft 71A and multiple first rollers 71B. The first shaft 71A is a rod-shaped member that constitutes the rotation axis of the first rotating member 71. The first shaft 71A is arranged along the scanning direction. Both ends of the first shaft 71A are rotatably supported by the frame 70A. The first rollers 71B are members that come into contact with the cylindrical medium M2. The first rollers 71B are made of a non-slip material and function as anti-slip surfaces that prevent the cylindrical medium M2 from slipping. For example, the first shaft 71A is made of metal, while the first rollers 71B are made of rubber. The multiple first rollers 71B are arranged at intervals along the first shaft 71A. The first rollers 71B may be fixed to the first shaft 71A or may be configured to be slidable along the first shaft 71A. At least some of the multiple first rollers 71B support the cylindrical medium M2.

[0039] The second rotating member 72 has a second shaft 72A and multiple second rollers 72B. The second shaft 72A is a rod-shaped member that constitutes the rotation axis of the second rotating member 72. The second shaft 72A is arranged along the scanning direction. Both ends of the second shaft 72A are rotatably supported by the frame 70A. The second rollers 72B are members that come into contact with the cylindrical medium M2. The second rollers 72B are made of a non-slip material and function as anti-slip surfaces that prevent the cylindrical medium M2 from slipping. For example, the second shaft 72A is made of metal, while the second rollers 72B are made of rubber. The multiple second rollers 72B are arranged at intervals along the second shaft 72A. The second rollers 72B may be fixed to the second shaft 72A or may be configured to be slidable along the second shaft 72A. At least some of the multiple second rollers 72B support the cylindrical medium M2.

[0040] The drive motor 73 is a motor for rotating the first rotating member 71 and the second rotating member 72. The drive motor 73 rotates the first rotating member 71 and the second rotating member 72, thereby rotating the cylindrical medium M2.

[0041] The transmission mechanism 74 is a mechanism that transmits the power of the drive motor 73 to the first rotating member 71 and the second rotating member 72. The transmission mechanism 74 is composed of, for example, gears, belts, etc. The transmission mechanism 74 is configured so that the first rotating member 71 and the second rotating member 72 rotate synchronously. The transmission mechanism 74 is configured so that when the drive motor 73 rotates in the forward direction, it rotates the cylindrical medium M2 in the direction indicated by the arrow in FIG. 5.

[0042] The encoder 75 is a device (rotary encoder) that detects the rotation amount of the drive motor 73. Here, the encoder 75 is built into the drive motor 73 and detects the rotation amount of the rotary shaft of the drive motor 73. However, the encoder 75 does not have to be built into the drive motor 73, and does not have to directly detect the rotary shaft of the drive motor 73. For example, the encoder 75 may indirectly detect the rotation amount of the drive motor 73 by detecting the rotation amount of a gear in the transmission mechanism 74. The encoder 75 outputs a pulse signal each time the rotary shaft of the drive motor 73 rotates by a predetermined angle. The controller 60 can detect the drive amount of the drive motor 73 (the rotation angle of the rotary shaft) by counting the number of pulses in the pulse signal from the encoder 75. Therefore, the encoder 75 functions as a detector that detects the drive amount of the drive motor 73. Alternatively, the drive motor 73 may be configured as a stepping motor, and the drive amount of the drive motor 73 may be detected based on the number of pulses input to the stepping motor instead of the encoder 75. In this case, the encoder 75 does not need to be provided.

[0043] The sensor 76 is a sensor for detecting the rotational position of the cylindrical medium M2. The sensor 76 detects a mark 80A (described later) that rotates together with the cylindrical medium M2. Here, the sensor 76 is configured as a reflective optical sensor. However, the sensor 76 may also be configured as a transmissive optical sensor, or may be configured as a magnetic sensor, camera, or the like. The mark 80A detected by the sensor 76 is provided on a mark unit 80 (described later). In the following description, the rotational position of the cylindrical medium M2 when the sensor 76 detects the mark 80A may be referred to as the "origin."

[0044] Here, the sensor 76 is provided on the frame 70A of the rotary unit 70. However, the sensor 76 does not have to be provided on the rotary unit 70. For example, the sensor 76 may be provided on the carriage 21 (described later).

[0045] <Mark Unit> 6A and 6B are explanatory diagrams of the mark unit 80. FIG.

[0046] The mark unit 80 is a unit for providing a mark 80A on the cylindrical medium M2 by utilizing the inner peripheral surface of the cylindrical medium M2. The mark unit 80 is detachable from the cylindrical medium M2. After the mark unit 80 is attached to the cylindrical medium M2, the cylindrical medium M2 with the mark unit 80 attached is placed on the rotation unit 70, and printing is performed on the outer peripheral surface of the cylindrical medium M2. When the cylindrical medium M2 with the mark unit 80 attached is rotated by the rotation unit 70, the mark unit 80 (and the mark 80A) rotates along with the cylindrical medium M2. After printing, the mark unit 80 can be removed from the cylindrical medium M2. The mark unit 80 has a gripping portion 81 and a mark 80A.

[0047] The gripping portion 81 is a portion that grips the cylindrical medium M2 and is a portion for attaching the mark unit 80 to the cylindrical medium M2. The cylindrical medium M2 is configured in a hollow cylindrical shape, and the gripping portion 81 is attached to the inner circumferential surface of the cylindrical medium M2. The gripping portion 81 is also called an inner diameter clamp.

[0048] The gripping portion 81 has a shaft portion 82 , a plurality of contact portions 83 , and a displacement mechanism 84 .

[0049] The shaft 82 is a rod-shaped member arranged along the axial direction of the cylindrical medium M2. The shaft 82 is a member arranged at the center of the mark unit 80, and is a member arranged at the center of the cylindrical medium M2 when the mark unit 80 is attached to the cylindrical medium M2. A mark 80A is provided on the shaft 82.

[0050] The contact portion 83 is a member that comes into contact with the inner circumferential surface of the cylindrical medium M2. The mark unit 80 is attached to the inside of the cylindrical medium M2 by the contact portions 83 coming into contact with the inner circumferential surface of the cylindrical medium M2. The contact portions 83 are arranged to surround the shaft portion 82. When viewed in the axial direction of the shaft portion 82, the contact portions 83 are arranged rotationally symmetrically with the shaft portion 82 as the center.

[0051] The displacement mechanism 84 is a mechanism for displacing the contact portions 83 in the radial direction (a direction perpendicular to the axial direction of the shaft portion 82). The displacement mechanism 84 displaces each of the multiple contact portions 83 in the radial direction so that the distance between each contact portion 83 and the shaft portion 82 is equal. When the gripping portion 81 grips the cylindrical medium M2 (when the marking unit 80 is attached to the inside of the cylindrical medium M2), the operator positions the shaft portion 82 and the contact portions 83 inside the cylindrical medium M2, and then uses the displacement mechanism 84 to displace each contact portion 83 in a direction away from the shaft portion 82, pressing each contact portion 83 against the inner circumferential surface of the cylindrical medium M2. As a result, when the gripping portion 81 grips the cylindrical medium M2 (when the marking unit 80 is attached to the inside of the cylindrical medium M2), the shaft portion 82 is positioned at the center of the cylindrical medium M2 (the position of the rotation axis). When removing the mark unit 80 from the cylindrical medium M2, the operator displaces each contact portion 83 in a direction approaching the shaft portion 82 using the displacement mechanism 84, thereby separating each contact portion 83 from the inner surface of the cylindrical medium M2.

[0052] The displacement mechanism 84 shown in FIG. 6A is configured as a screw-type pantograph jack and has a pair of arm support portions 84A and an arm 84B. A male thread is formed on the shaft portion 82, and the shaft portion 82 is inserted into the arm support portion 84A. One of the pair of arm support portions 84A is disposed at a predetermined axial position relative to the shaft portion 82, and the other arm support portion 84A has a female thread and is configured to be movable in the axial direction relative to the shaft portion 82. The arm 84B is disposed between the arm support portion 84A and the contact portion 83. By rotating the shaft portion 82, the axial distance between the pair of arm support portions 84A can be changed, and the contact portion 83 can be displaced radially.

[0053] It should be noted that the displacement mechanism 84 is not limited to the structure shown in Fig. 6A. Figs. 7A to 7C are explanatory diagrams of modified displacement mechanisms 84.

[0054] FIG. 7A is an explanatory diagram of a displacement mechanism 84 of a first modified example. The displacement mechanism 84 of the first modified example is configured with a spring-type pantograph jack. The displacement mechanism 84 of the first modified example has a pair of arm support portions 84A, an arm 84B, and a spring 84C. In the first modified example, it is disposed between the pair of arm support portions 84A. In the first modified example, the force of the spring 84C can press the contact portion 83 against the inner circumferential surface of the cylindrical medium M2.

[0055] FIG. 7B is an explanatory diagram of a displacement mechanism 84 of a second modified example. The displacement mechanism 84 of the second modified example is also configured with a spring-type pantograph jack. The displacement mechanism 84 of the second modified example has a pair of arm support portions 84A, a spring support portion 84D, an arm 84B, and a spring 84C. In the displacement mechanism 84 of the second modified example, the spring 84C is disposed between the arm support portion 84A and the spring support portion 84D. In the second modified example as well, the force of the spring 84C can be used to press the contact portion 83 against the inner circumferential surface of the cylindrical medium M2.

[0056] FIG. 7C is an explanatory diagram of a displacement mechanism 84 of a third modified example. The displacement mechanism 84 of the third modified example is configured with a wedge-type inner diameter clamp. The displacement mechanism 84 of the third modified example includes a spring 84C, a spring support portion 84D, and a wedge member 84E. A tapered surface is formed on the outer peripheral surface of the wedge member 84E. The wedge member 84E is configured to be axially slidable relative to the shaft portion 82. A tapered surface is also formed on the inner surface of the contact portion 83 (the surface opposite to the contact surface that contacts the cylindrical medium M2), and the outer peripheral surface of the wedge member 84E and the inner surface of the contact portion 83 are in contact. A spring 84C is disposed between the wedge member 84E and the spring support portion 84D. The wedge member 84E is biased by the spring 84C in the axial direction, and the force of the spring 84C can press the contact portion 83 against the inner peripheral surface of the cylindrical medium M2.

[0057] As described above, the displacement mechanism 84 is not limited to being configured as a pantograph, but may be configured as a wedge, or may be configured in other ways. Also, as described above, the displacement mechanism 84 is not limited to being configured as a screw, but may be configured as a spring, or may be configured in other ways. The displacement mechanism 84 may be configured in any way as long as it can displace the contact portion 83 in the radial direction and press the contact portion 83 against the inner circumferential surface of the cylindrical medium M2.

[0058] The mark 80A is a detection target that is detected by the sensor 76. The mark 80A functions as a marker that indicates the rotational position of the mark unit 80. By the sensor 76 detecting the mark 80A, the rotational position of the mark unit 80 can be detected, and as a result, the rotational position (origin) of the cylindrical medium M2 can be detected.

[0059] Here, because the sensor 76 is a reflective optical sensor, the mark 80A is made of a material capable of reflecting light. When the mark 80A is located at the origin, the mark 80A reflects light emitted from the light-emitting portion of the sensor 76, and the light-receiving portion of the sensor 76 receives the reflected light from the mark 80A. Note that when the mark 80A is located somewhere other than the origin, the amount of light received by the light-receiving portion of the sensor 76 decreases.

[0060] The mark 80A is not limited to being made of a material that can reflect light. For example, if the sensor 76 is made of a transmission-type optical sensor, the mark 80A will be made of a light-blocking material or a light-transmitting material (for example, a slit). If the sensor 76 is made of a magnetic sensor, the mark 80A will be made of, for example, a magnet. If the sensor 76 is made of a camera, the mark 80A may be made of a pattern that allows the origin and direction to be analyzed by, for example, image analysis. In this way, the mark 80A may have a configuration that can be detected by the sensor 76.

[0061] 6A and 6B has a shape that protrudes in the radial direction from the shaft portion 82. However, the shape of the mark 80A is not limited to this.

[0062] 8A and 8B are explanatory diagrams of a modified mark 80A. The modified mark 80A is a printed mark printed on the outer peripheral surface of the shaft portion 82. Therefore, the modified mark 80A does not protrude in the radial direction and is configured flat. In this way, the mark 80A is not limited to one that protrudes in the radial direction. Furthermore, the mark 80A does not have to have a three-dimensional shape.

[0063] The mark 80A may be configured to be detected in the axial direction as shown in FIG. 6A, in the radial direction as shown in FIG. 8A, or in a different direction. When the sensor 76 is configured to detect the mark 80A in the axial direction of the cylindrical medium M2 as shown in FIG. 6A, even if the position of the mark 80A shifts in the axial direction due to a shift in the mounting position of the mark unit 80 attached to the cylindrical medium M2, the sensor 76 can still detect the mark 80A. When the sensor 76 is configured to detect the mark 80A in the radial direction of the cylindrical medium M2 as shown in FIG. 8A, the sensor 76 can be disposed on a carriage 21 that can move in the scanning direction. The mark 80A and the sensor 76 are not limited to those shown in FIG. 6A or FIG. 8A, as long as they can detect that the cylindrical medium M2 is at a predetermined rotational position (origin).

[0064] <Printing method using the mark unit> 9 is a flow diagram of a printing method using the mark unit 80. Note that the processes of S001 to S003 in the diagram are performed by an operator. Also, S004 and S006 are performed by the printing device 1. Also, S005 is performed by the print control device 90.

[0065] First, the worker attaches the rotation unit 70 to the printing apparatus 1 (S001). Here, the worker fixes the rotation unit 70 to the table 31 of the printing apparatus 1, as shown in FIG.

[0066] Next, the worker attaches the mark unit 80 to the inside of the cylindrical medium M2 (S002). After inserting the shaft portion 82 and contact portion 83 of the mark unit 80 into the inside of the cylindrical medium M2, the worker displaces each contact portion 83 using the displacement mechanism 84 to press them against the inner circumferential surface of the cylindrical medium M2, thereby causing the gripping portion 81 to grip the cylindrical medium M2 from the inside. By attaching the mark unit 80 to the inside of the cylindrical medium M2, the mark 80A can be provided so that it rotates together with the cylindrical medium M2, without providing the mark 80A in the printing area (outer circumferential surface) of the cylindrical medium M2.

[0067] Next, the worker places the cylindrical medium M2 with the mark unit 80 attached on the rotation unit 70 (S003). As shown in Fig. 5, the worker places the cylindrical medium M2 between the first rotation member 71 and the second rotation member 72 of the rotation unit 70, and causes the first rotation member 71 and the second rotation member 72 to support the cylindrical shape.

[0068] After placing the cylindrical medium M2 on the rotation unit 70, the controller 60 (measurement processing unit 62) measures the size of the cylindrical medium M2 (measurement process; S004). In the measurement process, the controller 60 measures the drive amount of the drive motor 73 required to rotate the cylindrical medium M2 once.

[0069] Fig. 10 is a flow diagram of the measurement process. Each process in the diagram is performed by the arithmetic processing unit constituting the controller 60 (measurement processing unit 62) of the printer 1 executing a program stored in a storage device. Fig. 11 is an explanatory diagram showing the relationship between the count value of the number of pulses of the encoder 75 and the output of the sensor 76 during the measurement process.

[0070] First, the controller 60 (measurement processing unit 62) drives the drive motor 73 of the rotation unit 70 to rotate the cylindrical medium M2 (S011). Because the mark unit 80 is attached to the cylindrical medium M2, driving the drive motor 73 of the rotation unit 70 rotates the mark unit 80 along with the cylindrical medium M2. The controller 60 continues to drive the drive motor 73 until the sensor 76 detects the mark 80A (NO in S012). As the drive motor 73 continues to be driven, the mark unit 80 rotates together with the cylindrical medium M2, and the mark 80A reaches the detection position of the sensor 76. As a result, the sensor 76 detects the mark 80A (YES in S012). As shown in FIG. 11, when the sensor 76 detects the mark 80A, the output of the sensor 76 changes from L level to H level. When the sensor 76 detects the mark 80A (YES in S012), the rotation position of the cylindrical medium M2 is at the origin. Here, it is assumed that the rotational position of the cylindrical medium M2 is at the origin when the output of the sensor 76 rises from the L level to the H level.

[0071] When the sensor 76 detects the mark 80A (YES in S012), the controller 60 records the count value of the encoder 75 (S013). In the following description, the count value recorded at this time is referred to as the "start value." Here, the count value of the encoder 75 when the output of the sensor 76 rises from the L level to the H level is referred to as the "start value" (see FIG. 11). Note that in S013, the controller 60 may reset the count value of the encoder 75. In this case, the start value indicating zero is recorded.

[0072] After recording the count value (S013), the controller 60 drives the drive motor 73 of the rotation unit 70 to rotate the cylindrical medium M2 (S014). At this time, the controller 60 counts the number of pulses of the encoder 75 (the drive amount of the drive motor 73) while rotating the cylindrical medium M2 and the mark unit 80 from the rotation position of the origin.

[0073] The controller 60 continues driving the drive motor 73 until the sensor 76 again detects the mark 80A (NO in S015). Continuing to drive the drive motor 73 causes the mark unit 80 to rotate together with the cylindrical medium M2, and the mark 80A again reaches the detection position of the sensor 76, resulting in the sensor 76 again detecting the mark 80A (YES in S015). The cylindrical medium M2 has completed one rotation from the time the sensor 76 detected the mark 80A in S012 until the time the sensor 76 again detects the mark 80A in S015.

[0074] After the sensor 76 detects the mark 80A again (YES in S015), the controller 60 records the count value of the encoder 75 (S016). In the following description, the count value recorded at this time will be referred to as the "end value."

[0075] Based on the start value and end value, the controller 60 calculates the drive amount of the rotation unit 70 from the first time the sensor 76 detects the mark 80A (YES in S012) to the next time the sensor 76 detects the mark 80A (ES in S015) (S017). That is, the controller 60 calculates the drive amount of the drive motor 73 required to rotate the cylindrical medium M2 once. Here, the controller 60 calculates the difference between the end value and the start value. This difference value indicates the drive amount (count value) of the drive motor 73 required to rotate the cylindrical medium M2 once. Furthermore, this difference value (the drive amount of the drive motor 73 required to rotate the cylindrical medium M2 once) is a value corresponding to the size (peripheral length of the outer circumferential surface) of the cylindrical medium M2. The greater the peripheral length of the outer circumferential surface of the cylindrical medium M2, the greater the drive amount (here, the difference value) of the drive motor 73 required to rotate the cylindrical medium M2 once.

[0076] The controller 60 transmits data (size data) indicating the size of the cylindrical medium M2 to the print control device 90 (S018). Here, the controller 60 transmits the drive amount of the drive motor 73 (the difference between the end value and the start value) as the size data to the print control device 90. However, the size data is not limited to the drive amount (count value) of the drive motor 73. For example, the controller 60 may transmit to the print control device 90 the circumference (unit: mm) of the cylindrical medium M2 calculated by multiplying the difference between the end value and the start value (the drive amount of the drive motor 73) by a predetermined coefficient.

[0077] After receiving the size data from the printing device 1 (controller 60), the printing control device 90 (second command code generation unit 92) generates a command code (second command code) for printing an image on the cylindrical medium M2 (S005 in FIG. 9). The printing control device 90 generates the second command code based on the size data and transmits the second command code to the printing device 1.

[0078] For example, in the command code generation process, the print control device 90 (second command code generation unit 92) corrects the resolution of the print image based on the size data so that the length of the print image matches the circumferential length of the cylindrical medium M2. Note that the print control device 90 corrects the resolution of the print image so that the number of pixels of the print image (the number of pixels aligned along the circumferential direction of the cylindrical medium M2) increases as the circumferential length calculated based on the size data increases.

[0079] FIG. 12A is an explanatory diagram of a print image indicated by the second command code. FIG. 12B is an explanatory diagram of a print image printed on cylindrical medium M2 using the second command code. By adjusting the length L of the print image to the circumferential length of cylindrical medium M2 as shown in FIG. 12A, it is possible to prevent gaps from occurring between the top end (pixels at the start of printing) and the bottom end (pixels at the end of printing) of the print image printed on the outer surface of cylindrical medium M2, as shown in FIG. 12B, or to prevent the top and bottom ends of the print image from overlapping (see the arrows in FIG. 12B). The print control device 90 generates a second command code to cause the printer 1 to print the print image shown in FIG. 12A.

[0080] Note that the command code generation process does not necessarily require a process for correcting the resolution of the print image based on the size data. For example, during the command code generation process, the print control device 90 may correct the amount of rotation per rotation (the amount of rotation of the cylindrical medium M2 in the rotation performed between dot formation operations; the amount of rotation of the first rotating member 71 and the second rotating member 72; the amount of rotation of the drive motor 73) based on the size data, and generate a command code based on the corrected amount of rotation. By correcting the amount of rotation per rotation, it is possible to prevent gaps from occurring between the top end (pixels at the start of printing) and the bottom end (pixels at the end of printing) of the print image printed on the outer surface of the cylindrical medium M2, or to prevent the top and bottom ends of the print image from overlapping.

[0081] FIG. 12C is an explanatory diagram of a print image indicated by a second command code for causing the printer 1 to perform multi-layer printing. The figure shows a print image for the second command code when the printer 1 is to perform three-layer printing. The print control device 90 (second command code generation unit 92) corrects the print image based on size data so that the length L of each of the three images fits the circumferential length of the cylindrical medium M2, and arranges the three images consecutively along the circumferential direction of the cylindrical medium M2. By causing the printer 1 to perform multi-layer printing based on such a second command code, three images can be printed consecutively while rotating the cylindrical medium M2 in one direction, allowing the printer 1 to perform three-layer printing. Because the images for multi-layer printing can be printed consecutively, it is not necessary to rotate the cylindrical medium M2 in the reverse direction to the print start position after finishing printing the image for one layer and before starting printing the image for another layer, thereby improving printing speed. In addition, the bottom edge of an image on one layer and the top edge of an image on the next layer can be printed together (in other words, in a dot formation operation, dots on an image on one layer and dots on an image on the next layer can be formed together), thereby improving printing speed.

[0082] After receiving the second command code from the print control device 90, the controller 60 (print processing unit 61) of the printing device 1 prints an image on the outer peripheral surface of the cylindrical medium M2 in accordance with the received second command code. That is, the controller 60 performs a second printing process in S006. In the second printing process, the controller 60 alternately performs a dot formation operation in which the head 10 is driven to move the head 10 in the scanning direction while ejecting ink from the head 10 to form dots on the medium, and the irradiation unit 50 (light source 51) is irradiated with ultraviolet light to harden the dots, and a rotation operation in which the rotation unit 70 (drive motor 73) is driven by a predetermined rotation amount to rotate the cylindrical medium M2, thereby printing an image on the outer peripheral surface of the cylindrical medium M2 (note that the command code generation process described above generates a command code for performing this second printing process). This prevents gaps from occurring between the top end (pixels where printing starts) and bottom end (pixels where printing ends) of the printed image printed on the outer surface of the cylindrical medium M2, or prevents the top and bottom ends of the printed image from overlapping (see the area indicated by the arrow in Figure 12B).

[0083] <Modification> In the above description, the mark 80A is attached to the cylindrical medium M2 by attaching the mark unit 80 having the mark 80A to the cylindrical medium M2. However, the mark 80A may be attached to the cylindrical medium M2 by using the inner peripheral surface of the cylindrical medium M2 without using the mark unit 80.

[0084] FIG. 13 is an explanatory diagram of the state during measurement processing in the modified example.

[0085] In this modification, the mark 80A is attached to the inner circumferential surface of the cylindrical medium M2. Instead of attaching the mark unit 80 to the cylindrical medium M2 (see S002 in FIG. 9), the worker attaches the mark 80A to the inner circumferential surface of the cylindrical medium M2.

[0086] In a modified example, the sensor 76 is disposed inside the cylindrical medium M2. This allows the sensor 76 to detect the mark 80A affixed to the inner circumferential surface. In this case, the sensor 76 detects the mark 80A from the radial direction.

[0087] <Summary> The printing device 1 includes a head 10 that ejects ink, a rotation unit 70 that rotates a cylindrical medium M2 (a cylindrical medium), a sensor 76, and a controller 60 that calculates the amount of drive of the rotation unit 70 from when the sensor 76 detects a mark 80A until when the sensor 76 detects the mark 80A again after the cylindrical medium M2 has further rotated. In this embodiment, the sensor 76 is configured to detect the mark 80A attached to the cylindrical medium M2 using the inner circumferential surface of the cylindrical medium M2 (see FIGS. 6A, 7A-7C, 8A, and 13). In this embodiment, the mark 80A does not need to be provided on the outer circumferential surface of the cylindrical medium M2, and therefore the size of the cylindrical medium M2 can be measured without the mark 80A interfering with printing on the outer circumferential surface.

[0088] The mark 80A is provided on a mark unit 80 that has a gripping portion 81 that grips the inner circumferential surface of the cylindrical medium M2 and is detachable from the cylindrical medium M2 (see FIGS. 6A, 7A to 7C, and 8A). This allows the mark unit 80 to be detached from the cylindrical medium M2 after printing on the cylindrical medium M2, and the mark 80A can be removed from the cylindrical medium M2.

[0089] Moreover, the gripping portion 81 has a shaft portion 82 arranged along the axial direction of the cylindrical medium M2, a contact portion 83 arranged to surround the shaft portion 82, and a displacement mechanism 84 that radially displaces the contact portion 83 relative to the shaft portion 82. With this configuration, the displacement mechanism 84 displaces the contact portion 83 radially, and the contact portion 83 comes into contact with the inner circumferential surface of the cylindrical medium M2, thereby allowing the gripping portion 81 to grip the inner circumferential surface of the cylindrical medium M2.

[0090] 6A and 7A to 7C detects the mark 80A from the axial direction of the cylindrical medium M2. In this way, if the sensor 76 is configured to detect the mark 80A from the axial direction of the cylindrical medium M2, the sensor 76 can detect the mark 80A even if the attachment position of the mark unit 80 attached to the cylindrical medium M2 is shifted and the position of the mark 80A is shifted in the axial direction.

[0091] 8 detects the mark 80A from the radial direction of the cylindrical medium M2. Even in this way, the sensor 76 can still detect the mark 80A. In this case, it is desirable that the sensor 76 be provided on the carriage 21, which is movable in the scanning direction. This allows the sensor 76 to detect the mark 80A even if the position of the mark 80A is shifted in the scanning direction due to a shift in the mounting position of the mark unit 80 attached to the cylindrical medium M2.

[0092] As shown in FIG. 13, the mark 80A may be affixed to the inner circumferential surface of the cylindrical medium M2. This allows the mark 80A to be attached to the cylindrical medium M2 by utilizing the inner circumferential surface of the cylindrical medium M2 without using the mark unit 80. Note that when the mark 80A is affixed to the inner circumferential surface of the cylindrical medium M2, the mark 80A will be positioned inside the cylindrical medium M2. For this reason, when the mark 80A is affixed to the inner circumferential surface of the cylindrical medium M2, it is desirable that the sensor 76 detects the mark 80A from inside the cylindrical medium M2, as shown in FIG.

[0093] The aforementioned controller 60 prints on the outer peripheral surface of the cylindrical medium M2 in accordance with a command code generated based on the drive amount of the rotation unit 70 when rotating the cylindrical medium M2 once. This allows an image to be printed on the outer peripheral surface of the cylindrical medium M2 in accordance with the size (periphery length of the outer peripheral surface) of the cylindrical medium M2. This also prevents gaps from occurring between the top and bottom of the printed image or overlapping of the top and bottom of the printed image.

[0094] In addition, in the above-described printing method, a mark 80A is attached to the cylindrical medium M2 using the inner circumferential surface of the cylindrical medium M2, the medium is placed on the rotation unit 70, the rotation unit 70 rotates the cylindrical medium M2, the amount of drive of the rotation unit 70 per rotation of the cylindrical medium M2 is calculated, and printing is performed on the outer circumferential surface of the cylindrical medium M2 based on the calculated amount of drive. According to the printing method of this embodiment, since it is not necessary to provide the mark 80A on the outer circumferential surface of the cylindrical medium M2, the size of the cylindrical medium M2 can be measured without the mark 80A interfering with printing on the outer circumferential surface, and an image can be printed on the outer circumferential surface of the cylindrical medium M2 in accordance with the size (periphery of the outer circumferential surface) of the cylindrical medium M2. This also prevents gaps from occurring between the top and bottom of the printed image or overlapping of the top and bottom of the printed image. In the above explanation, methods for attaching a mark 80A to a cylindrical medium M2 using the inner surface of the cylindrical medium M2 were described, including a method of attaching a mark unit 80 to the inside of the cylindrical medium M2 and attaching the mark 80A to the medium, and a method of attaching the mark 80A to the inner surface of the cylindrical medium M2 without using the mark unit 80.However, the method of attaching a mark 80A to a cylindrical medium M2 using the inner surface of the cylindrical medium M2 is not limited to these methods, and other methods may also be used.

[0095] Furthermore, the mark unit 80 described above includes a gripping portion 81 and a mark 80A provided on the gripping portion 81, and the gripping portion 81 is configured to grip the inner peripheral surface of the cylindrical medium M2. This eliminates the need to provide the mark 80A on the outer peripheral surface of the cylindrical medium M2, and allows the size of the cylindrical medium M2 to be measured without the mark 80A interfering with printing on the outer peripheral surface.

[0096] ===Other embodiments=== The above-described embodiments are presented as examples and do not limit the scope of the invention. The above configurations can be implemented in appropriate combinations, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. The above-described embodiments and their modifications are included in the scope and spirit of the invention, as well as in the inventions described in the claims and their equivalents. [Explanation of symbols]

[0097] 1 Printer, 1A base, 10 heads, 20 carriage unit, 21 carriage, 22 carriage motor, 23 guide, 30 transport unit, 31 table, 32 transport motor, 40 lifting unit, 41 lifting member, 42 lifting motor, 50 irradiation unit, 51 light source, 60 controller, 61 printing processing unit, 62 measurement processing unit, 70 rotation unit, 70A frame, 71 first rotating member, 71A first shaft, 71B first roller, 72 second rotating member, 72A second shaft, 72B second roller, 73 Drive motor, 74 Transmission mechanism, 75 Encoders, 76 Sensors, 80 mark unit, 80A mark, 81 Gripping part, 82 Shaft part, 83 Contact part, 84 displacement mechanism, 84A arm support part, 84B Arm, 84C Spring, 84D spring support portion, 84E wedge member, 90 Printing control device, 90A Display device, 90B Input device, 91 first command code generation unit, 92 second command code generation unit, 93 communication unit, 100 printing systems, M1 medium, M2 Cylindrical medium (medium with a cylindrical shape)

Claims

1. a head that ejects ink; a rotation unit that rotates a cylindrical medium that is the target of printing using the head; a sensor that detects a mark attached to the medium by utilizing the inner peripheral surface of the medium; a controller that calculates the amount of drive of the rotation unit from when the sensor detects the mark while rotating the medium to when the sensor detects the mark while further rotating the medium; A printing device comprising:

2. 2. The printing device according to claim 1, A printing device characterized in that the mark is provided on a mark unit that has a gripping portion that grips the inner peripheral surface of the medium and is detachable from the medium.

3. 3. The printing device according to claim 2, The gripping portion is a shaft portion disposed along the axial direction of the medium; a plurality of contact portions arranged to surround the shaft portion and in contact with the inner circumferential surface; a displacement mechanism that displaces the contact portion in a radial direction relative to the shaft portion; A printing device comprising:

4. 4. The printing device according to claim 3, The printing device is characterized in that the sensor detects the mark in the axial direction.

5. 4. The printing device according to claim 3, The printing device is characterized in that the sensor detects the mark from the radial direction.

6. 6. The printing device according to claim 5, The head is provided on a carriage that moves in a scanning direction, The printing apparatus is characterized in that the sensor is provided on the carriage.

7. 2. The printing device according to claim 1, the mark is affixed to the inner circumferential surface of the medium, The printing device is characterized in that the sensor detects the mark from inside the medium.

8. The printing device according to any one of claims 1 to 7, The printing device is characterized in that the controller performs printing on the outer peripheral surface of the medium in accordance with a command code generated based on the drive amount.

9. Attaching a mark to a cylindrical medium by utilizing the inner peripheral surface of the medium; placing the medium on a rotary unit provided in a printing device that performs printing on the outer peripheral surface of the medium; rotating the medium with the rotation unit; determining the amount of drive of the rotation unit from when the sensor detects the mark while rotating the medium to when the sensor detects the mark while further rotating the medium; performing printing on the outer peripheral surface of the medium based on the driving amount; Printing method.

10. a gripping portion that grips the inner peripheral surface of a cylindrical medium to be printed; a mark provided on the gripping portion, the mark being detected by a sensor to indicate the rotational position of the medium; A mark unit comprising:

Images