Printing apparatus

Abstract

If the output of the heater that heats the ink is low, there is a risk that insufficiently heated ink will be supplied. The printing apparatus according to this disclosure aims to suppress the supply of insufficiently heated ink. [Solution] The printing apparatus according to the present disclosure comprises a head for ejecting ink onto a medium, a damper for storing the ink and supplying the ink to the head, a heating unit for heating the ink with a heating heater upstream of the damper in the ink supply direction, and a controller for supplying the ink from the heating unit to the damper after raising the temperature of the heating heater.

Description

Technical Field

[0001] The present invention relates to a printing apparatus.

Background Art

[0002] Patent Document 1 describes a printing apparatus provided with a damper. The damper alleviates the pressure fluctuations of the ink and stabilizes the ejection of the ink from the head.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] Other features of the present invention will be revealed by the description herein. [Effects of the Invention]

[0008] According to the present invention, it is possible to suppress the supply of unheated ink to the damper. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic diagram of the printing apparatus 100. [Figure 2] Figure 2 is a block diagram of the printing device 100. [Figure 3] Figure 3 is an explanatory diagram of the ink supply unit 5. [Figure 4] Figure 4 is a side view of the damper 60. [Figure 5] Figure 5 is a cross-sectional view of the damper 60. [Figure 6] Figure 6 is a perspective view of the damper 60. [Figure 7] Figure 7 is a flow chart of the ink supply process. [Figure 8] Figure 8 is an explanatory diagram of the damper 60 of the first modified example. [Figure 9] Figure 9 is an explanatory diagram of the damper 60 of the second modified example. [Figure 10] Figure 10 is an explanatory diagram of another form of the heat conductor 67 in the second modified example. [Figure 11] Figure 11 is an explanatory diagram of a modified ink supply unit 5. [Figure 12] Figure 12A is an explanatory diagram showing how ink is sent from ink cartridge 5A to print head 10. Figure 12B is an explanatory diagram showing how ink is circulated. [Figure 13] Figure 13 is an explanatory diagram of the heat exchange section 95. [Modes for carrying out the invention]

[0010] ===Embodiment=== <Overall Configuration> FIG. 1 is a schematic explanatory diagram of the printing apparatus 100. FIG. 2 is a block diagram of the printing apparatus 100.

[0011] In the following description, the direction in which the carriage 21 (or the head 10) moves may be referred to as the "scanning direction" or the "left - right direction". Among the left - right directions, the right side as viewed from the operator who operates the printing apparatus 100 may be referred to as "right", and the opposite side may be referred to as "left". Also, the vertical direction may be referred to as the "up - down direction", the upper side in the vertical direction may be referred to as "up", and the opposite side may be referred to as "down". Further, the direction perpendicular to the scanning direction and the up - down direction may be referred to as the "front - back direction". Among the front - back directions, the side of the operator who operates the printing apparatus 100 as viewed from the printing apparatus 100 may be referred to as "front", and the opposite side may be referred to as "back".

[0012] The printing apparatus 100 is an apparatus that performs printing on a medium M. Here, the printing apparatus 100 discharges a photocurable ink (here, an ultraviolet - curable ink) onto the medium M and irradiates light (here, ultraviolet light) onto the dots formed on the medium M to cure the dots. That is, the printing apparatus 100 is a so - called UV printer. However, the ink discharged by the printing apparatus 100 onto the medium M does not have to be a photocurable ink.

[0013] The printing apparatus 100 includes a head 10, a carriage unit 20, a conveyance unit 30, an irradiation unit 40, an ink supply unit 5, and a controller 80.

[0014] The head 10 ejects ink. Here, the head 10 ejects an ultraviolet-curable ink (so-called UV ink) that cures when irradiated with ultraviolet light. However, the ink ejected by the head 10 is not limited to photo-curable ink (ultraviolet-curable ink). The head 10 is mounted on the carriage 21 and is movable in the scanning direction. The head 10 ejects color inks such as cyan, magenta, yellow, and black, for example. Note that the head 10 may eject white ink or silver ink. A plurality of nozzle rows are provided on the lower surface of the head 10. Nozzle rows are provided on the lower surface of the head 10 for each color of ink. For example, a cyan nozzle row for ejecting cyan ink, a magenta nozzle row for ejecting magenta ink, a yellow nozzle row for ejecting yellow ink, a black nozzle row for ejecting black ink, etc. are provided. Note that the region where liquid (ink) is ejected onto the medium M may be referred to as the "printing region". The printing region is the region facing the nozzle row of the head 10. The printing apparatus 100 has one or more heads 10, and one or more heads 10 are mounted on the carriage 21.

[0015] The carriage unit 20 moves the carriage 21 in the scanning direction. The carriage unit 20 has the carriage 21 and the carriage motor 22. The carriage 21 mounts the head 10 and is reciprocally movable in the scanning direction. The carriage motor 22 is a driving source for moving the carriage 21. Note that the carriage unit 20 has a transmission mechanism (not shown; for example, gears, pulleys, belts, etc.) for transmitting the driving force of the carriage motor 22 to the carriage 21.

[0016] The transport unit 30 transports the medium M. The transport unit 30 has a transport member 31 and a transport motor 32. The transport member 31 is a member that transports the medium M, and in this case has a transport roller and a pinch roller. The transport motor 32 is a drive source that rotates the transport member 31 (in this case the transport roller). When the medium M is sandwiched between the transport roller and the pinch roller, the transport motor 32 rotates the transport roller, causing the medium M to be transported in the transport direction.

[0017] The irradiation unit 40 irradiates the medium M with light. Here, the irradiation unit 40 has a light source 41 that emits ultraviolet (UV) light, and is configured to irradiate the medium M with ultraviolet light emitted from the light source 41. The light source 41 is composed of, for example, an LED array in which multiple LEDs (UV-LEDs) are arranged. The irradiation unit 40 is mounted on the carriage 21. Therefore, the irradiation unit 40 can move along the scanning direction together with the carriage 21 (and head 10), and can irradiate the printing area with light. Note that if the ink ejected by the head 10 is not a photocurable ink (UV-curable ink), the printing apparatus 100 does not need to be equipped with the irradiation unit 40.

[0018] The ink supply unit 5 supplies ink to the print head 10. The configuration of the ink supply unit 5 will be described later.

[0019] The controller 80 controls the printing device 100. The controller 80 has, for example, an arithmetic processing unit and a memory device (not shown), and various processes are performed by the arithmetic processing unit executing a program stored in the memory device. The controller 80 has a printing processing unit 81 and an ink supply processing unit 82.

[0020] The printing processing unit 81 causes the printing device 100 to perform a printing process on the medium M. Specifically, the printing processing unit 81 alternately repeats a dot formation operation, in which the carriage unit 20 (carriage motor 22) drives the head 10 to move in the scanning direction and ejects ink from the head 10 to form dots on the medium M, and a transport operation, in which the transport unit 30 transports the medium M in the transport direction, thereby printing an image on the medium M. In addition, during the printing operation, the printing processing unit 81 hardens the dots by irradiating the medium M with light (in this case, ultraviolet light) from the irradiation unit 40.

[0021] The ink supply processing unit 82 causes the printing device 100 to perform the process of supplying ink to the print head 10 (ink supply process). The ink supply process will be described later.

[0022] <Ink supply unit> Figure 3 is an explanatory diagram of the ink supply unit 5.

[0023] The ink supply unit 5 supplies ink from the ink cartridge 5A to the print head 10. The ink supply unit 5 has supply paths 5C for supplying ink to the print head 10 for each type of ink. Figure 3 shows two supply paths 5C, but if the print head 10 ejects four types of ink, then four supply paths 5C will be provided for the print head 10. The ink cartridge 5A is the source of the ink and is detachably installed in the printing device 100. There will be one ink cartridge 5A for each type of ink.

[0024] In the following explanation, the direction in which ink flows from ink cartridge 5A towards print head 10 may be referred to as the "ink flow direction." Furthermore, the upstream and downstream sides of this ink flow direction may be referred to as the "upstream side of the ink flow direction" and the "downstream side of the ink flow direction," respectively. Ink cartridge 5A is located furthest upstream in the ink flow direction, and print head 10 is located furthest downstream in the ink flow direction.

[0025] The ink supply unit 5 comprises a liquid transfer pump 5B, a heating unit 50, a damper 60, and a heat retention unit 70. The ink cartridge 5A and the liquid transfer pump 5B are located on the main body side of the printing device 100, while the heating unit 50, damper 60, and heat retention unit 70 are located on the carriage 21. The liquid transfer pump 5B, heating unit 50, and damper 60 are provided for each type of ink. On the other hand, a heat retention unit 70 is provided for each print head 10. If the print head 10 ejects multiple types of ink, a common heat retention unit 70 will be provided for multiple supply lines 5C.

[0026] The liquid delivery pump 5B is a component (liquid delivery unit) for delivering ink towards the print head 10. The liquid delivery pump 5B is located on the main body side of the printing device 100 and is situated between the ink cartridge 5A and the carriage 21. The liquid delivery pump 5B can be driven and stopped by the controller 80. Alternatively, the ink supply unit 5 may use hydrostatic pressure to supply ink instead of using the liquid delivery pump 5B. In this case, the ink supply unit 5 is equipped with an on-off valve instead of the liquid delivery pump 5B, and the controller 80 controls the opening and closing of the on-off valve to supply ink from the ink cartridge 5A to the print head 10. In this case, the on-off valve functions as the liquid delivery section (a component for supplying ink towards the print head 10).

[0027] The heating unit 50 heats the ink to raise its temperature. Here, the heating unit 50 heats the ink supplied from the ink cartridge 5A so that it reaches 35-45°C. If the ink temperature falls below the lower limit of 35°C, the viscosity of the ink will increase, which may cause unstable ink ejection from the head 10. In contrast, the heating unit 50 heats the ink to a predetermined viscosity, which stabilizes ink ejection from the head 10. On the other hand, if the ink temperature rises above the upper limit of 50°C, the composition of the ink may change. Therefore, the heating unit 50 needs to heat the ink so that its temperature is 35°C or higher, while ensuring that the ink temperature does not rise above 50°C. In other words, in this embodiment, there are limitations on the output of the heater that heats the ink (heating heater 51; described later), and there are limitations on increasing the heater temperature. Note that the lower and upper limits of the ink temperature are not limited to 35°C and 50°C.

[0028] In the following description, the ambient temperature (room temperature; e.g., 20°C) will be denoted as Ta. The set temperature of the ink supplied to the print head 10 (e.g., 35°C) will be denoted as Tp. The upper limit temperature of the ink (e.g., 50°C) will be denoted as Tmax. The heating unit 50 is configured to heat the ink from Ta to Tp while ensuring that the ink temperature does not exceed Tmax.

[0029] The heating unit 50 is mounted on the carriage 21. The heating unit 50 is located downstream of the liquid transfer pump 5B in the liquid transfer direction. The heating unit 50 is located between the liquid transfer pump 5B and the damper 60. In other words, the heating unit 50 is located upstream of the damper 60 in the liquid transfer direction.

[0030] A heating unit 50 is provided for each type of ink. The amount of ink consumed during the printing process differs for each type of ink, but by providing a heating unit 50 for each type of ink, it becomes possible to heat each ink according to its respective consumption.

[0031] The heating unit 50 includes a heating heater 51, a supply port 52, an outlet 53, a heating channel 54, and an insulating case 55.

[0032] The heating element 51 is a heat source for heating the ink. The heating element 51 is constructed in the form of a thin sheet and is flat. The heating element 51 is sometimes called a film heater or film sheet heater. However, the heating element 51 does not have to be constructed in the form of a sheet. The heating element 51 is a heater that can heat the ink temperature from Ta to Tp while ensuring that the ink temperature does not exceed Tmax. The heating element 51 can be driven and stopped by the controller 80, and its temperature can also be controlled.

[0033] The supply port 52 is the part (inlet) through which ink is introduced from the outside to the inside of the heating unit 50. A tube is connected to the supply port 52 to introduce ink from the outside to the inside of the carriage 21. The discharge port 53 is the part (outlet) that leads the ink from the inside of the heating unit 50 to the outside. A tube that supplies ink from the heating unit 50 to the damper 60 is connected to the discharge port 53.

[0034] The heating channel 54 is a channel provided between the supply port 52 and the discharge port 53. The ink is heated by the heating heater 51 while flowing through the heating channel 54. The heating channel 54 is positioned opposite the heating surface of the heating heater 51. In other words, the heating channel 54 is configured so that the ink flows along the heating surface of the heating heater 51. By configuring the heating channel 54 so that the ink flows along the heating surface of the heating heater 51, a structure is created that makes it easier to heat the ink. Furthermore, in situations where the output of the heating heater 51 is restricted so that the ink temperature does not rise above Tmax (for example, 50°C), a structure that makes it easier to heat the ink is particularly effective.

[0035] The insulated case 55 insulates the ink in the heating unit 50. The insulated case 55 is made of an insulating material. The insulated case 55 is configured to house the heating heater 51 and the heating channel 54. By housing the heating heater 51 and the heating channel 54 in the insulated case 55, the temperature drop of the heated ink (ink in the heating channel 54) can be suppressed.

[0036] The insulated cases 55 are provided for each type of ink (because the heating units 50 are provided for each type of ink). Therefore, when the set temperature of the heating heater 51 is set according to the consumption of each ink (as described later), the set temperature for each ink can be maintained.

[0037] The damper 60 is an ink storage component. The damper 60 has the function of mitigating fluctuations in ink pressure at the print head 10. The presence of the damper 60 stabilizes the ink ejection from the print head 10. The damper 60 is located upstream of the print head 10 in the ink flow direction and is situated between the heating unit 50 and the print head 10.

[0038] Figure 4 is a side view of the damper 60. Figure 5 is a cross-sectional view of the damper 60. Note that Figure 5 shows the AA cross-section of the damper 60 shown in Figure 4. Figure 6 is a perspective view of the damper 60.

[0039] The damper 60 comprises a main body case 61, a damper membrane 62, a spring 63, and a pressure receiving plate 64.

[0040] The main body case 61 is a component that constitutes the main body of the damper 60. The main body case 61 is a hollow component with one side open. The main body case 61 is provided with an inlet 61A through which ink flows in and an outlet 61B through which ink flows out. The inlet 61A is connected to the heating unit 50 via a tube, and the outlet 61B is connected to the head 10. The damper membrane 62 is a component that covers the opening of the main body case 61 and is an elastically deformable film-like component. The space enclosed by the main body case 61 and the damper membrane 62 becomes a storage chamber for storing ink. The spring 63 is a component that presses against the damper membrane 62 and is made of tapered spring material. One end of the spring 63 is fixed to the inner wall surface of the main body case 61 (the inner wall surface facing the damper membrane 62), and the other end of the spring 63 is fixed to the pressure plate 64. The pressure plate 64 is a plate-shaped member that presses against the damper membrane 62. The pressure plate 64 presses the damper membrane 62 outward by the force of the spring 63. The pressure plate 64 is positioned approximately in the center of the damper membrane 62 and is circular in shape in order to press the damper membrane 62 uniformly. As shown in Figure 5, the pressure plate 64 presses against the damper membrane 62, causing the damper membrane 62 to deform and bend outward. The bending of the damper membrane 62 changes depending on the amount of ink in the damper 60. Specifically, the less ink there is in the damper 60, the more the damper membrane 62 shown in Figure 5 deforms inward.

[0041] The damper 60 has an ink volume detection unit 65. The ink volume detection unit 65 detects the amount of ink in the damper 60. Here, the ink volume detection unit 65 has a lever 651 and a sensor 652. The lever 651 is positioned outside the damper membrane 62 and is in contact with the damper membrane 62. One end of the lever 651 is rotatably supported by the main body case 61. The other end of the lever 651 is a free end and is displaced in accordance with the bending deformation of the damper membrane 62. The other end of the lever 651 is provided with a detectable portion 651A that is detected by the sensor 652. The sensor 652 detects the detectable portion 651A of the lever 651 and outputs a signal corresponding to the position of the detectable portion 651A of the lever 651. The sensor 652 outputs the detection result to the controller 80. Based on the detection result of the sensor 652, the controller 80 can detect the amount of ink in the damper 60. The ink amount detection unit 65 may have other configurations as long as it can detect the amount of ink in the damper 60. For example, the ink amount detection unit 65 may detect the amount of ink in the damper 60 based on the detection result of a pressure sensor that detects the pressure inside the damper 60.

[0042] In this embodiment, the heating unit 50 is positioned upstream of the damper 60 in the liquid delivery direction. If the heating unit 50 were positioned downstream of the damper 60 in the liquid delivery direction, the pressure loss in the heating channel 54 of the heating unit 50 would make it difficult for the damper 60 to mitigate pressure fluctuations within the head 10. In contrast, by positioning the heating unit 50 upstream of the damper 60 in the liquid delivery direction, the pressure loss in the channel between the damper 60 and the head 10 can be suppressed, resulting in a structure that makes it easier for the damper 60 to mitigate pressure fluctuations within the head 10. However, because the heating unit 50 is positioned upstream of the damper 60 in the liquid delivery direction, there is a risk that the ink heated to a predetermined temperature in the heating unit 50 may cool down before being ejected from the head 10. Therefore, a heat retention unit 70 is provided to prevent the ink heated in the heating unit 50 from cooling down.

[0043] The heat retention unit 70 maintains the ink temperature downstream of the heating unit 50 in the liquid flow direction. The heat retention unit 70 includes a heat retention heater 71, an insulating case 72, and a temperature sensor 73.

[0044] The heat-retaining heater 71 is a heat source for keeping the ink warm. The heat-retaining heater 71 only needs to maintain the ink, which has been heated by the heating unit 50, at a predetermined temperature. Therefore, compared to the heating heater 51, which heats the ink from Ta to Tp, the heat-retaining heater 71 is composed of a heater with a lower output. The heat-retaining heater 71 can be driven and stopped by the controller 80, and its temperature can also be controlled.

[0045] The insulating case 72 insulates the ink downstream of the heating unit 50 in the liquid delivery direction. The insulating case 72 is made of insulating material. The insulating case 72 is configured to house the damper 60. By housing the damper 60, the insulating case 72 can insulate the ink stored in the damper 60, making it easier to suppress the cooling of the ink heated by the heating unit 50. The insulating case 72 houses multiple dampers 60. In other words, multiple dampers 60 are housed in a common insulating case 72. This simplifies the structure of the heat retention unit 70. However, an insulating case 72 may be provided for each type of ink, or in other words, for each damper 60. In this case, it is possible to maintain different temperatures for each type of ink. Here, the insulating case 72 is configured not only to house the damper 60 but also to house the flow path between the damper 60 and the head 10. However, the scope of what the insulating case 72 houses is not limited to this. For example, the carriage 21 can be made into an insulated case by covering the inner wall surface of the carriage 21 with insulating material.

[0046] The temperature sensor 73 detects the temperature inside the insulated case 72. The temperature sensor 73 is located inside the insulated case 72. The temperature sensor 73 outputs a signal corresponding to the temperature inside the insulated case 72. The temperature sensor 73 outputs the detection result to the controller 80. Based on the detection result of the temperature sensor 73, the controller 80 controls the heating element 71 to maintain the inside of the insulated case 72 at a predetermined temperature Tp (for example, 35°C).

[0047] <Ink supply process> Figure 7 is a flowchart of the ink supply process. Each process in Figure 7 is executed by the controller 80 (ink supply processing unit 82) controlling each component of the printing device 100. The controller 80 (ink supply processing unit 82) executes the ink supply process for each type of ink (for each system of the supply path 5C).

[0048] First, the ink supply processing unit 82 sets the temperature of the heating heater 51 to Tp (for example, 35°C) and also sets the temperature of the retaining heater 71 to Tp (S001). In the following description, the setting of the heating heater 51 in S001 may be referred to as the "normal setting" or "first setting".

[0049] Next, the ink supply processing unit 82 determines whether the amount of ink in the damper 60 is below a first threshold (S002). The first threshold is a threshold used to determine whether or not to supply ink to the damper 60. When the amount of ink in the damper 60 falls below the first threshold, the ink supply processing unit 82 determines that it is necessary to supply ink to the damper 60. For example, the ink supply processing unit 82 determines the amount of ink in the damper 60 based on the detection result of the ink amount detection unit 65 of the damper 60, and compares the amount of ink in the damper 60 with the first threshold.

[0050] If the ink supply processing unit 82 determines that the amount of ink in the damper 60 is greater than the first threshold (NO in S002), it does not supply ink to the damper 60 because there is sufficient ink stored in the damper 60. However, when the controller 80 (printing processing unit 81) executes a printing process and ink is ejected from the head 10, the amount of ink in the damper 60 decreases. When the amount of ink in the damper 60 decreases due to the execution of the printing process, the amount of ink in the damper 60 reaches the first threshold. In addition, the amount of ink in the damper 60 may also reach the first threshold when ink is ejected from the head 10 due to processes other than printing, such as the cleaning process of the head 10.

[0051] If the ink supply processing unit 82 determines that the amount of ink in the damper 60 is below a first threshold (YES in S002), it raises the set temperature of the heating heater 51 from Tp (e.g., 35°C) to Tmax (e.g., 50°C) (S003). In this embodiment, the ink supply processing unit 82 raises the set temperature of the heating heater 51 before driving the liquid transfer pump 5B to supply ink to the damper 60 in S005. The reason for this will be explained later. In the following explanation, the setting of the heating heater 51 in S003 may be referred to as the "heating setting" or "second setting".

[0052] The ink supply processing unit 82 raises the set temperature of the heating heater 51 to Tmax (for example, 50°C) (S003), and after a predetermined time has elapsed (YES in S004), starts driving the liquid transfer pump 5B (S005). The driving of the liquid transfer pump 5B supplies ink to the heating unit 50, and ink is also supplied from the heating unit 50 to the damper 60. At this time, the damper 60 is supplied with ink heated by the heating unit 50.

[0053] The ink supply processing unit 82 determines whether the amount of ink in the damper 60 is equal to or greater than the second threshold while the liquid delivery pump 5B is being driven (S006). The second threshold is used to determine whether sufficient ink has been stored in the damper 60. The second threshold is a value greater than the first threshold used in the determination in S002. The ink supply processing unit 82 will continue to drive the liquid delivery pump 5B until the amount of ink in the damper 60 reaches the second threshold (NO in S006). If the operation of the liquid delivery pump 5B continues, the amount of ink in the damper 60 will reach the second threshold.

[0054] If the ink supply processing unit 82 determines that the amount of ink in the damper 60 is equal to or greater than the second threshold (YES in S006), it stops the liquid transfer pump 5B (S007). Stopping the liquid transfer pump 5B stops the supply of ink to the heating unit 50, and also stops the supply of ink from the heating unit 50 to the damper 60. Furthermore, the ink supply processing unit 82 sets the temperature of the heating heater 51 to Tp (for example, 35°C) (S008). In other words, the ink supply processing unit 82 returns the setting of the heating heater 51 from the heating setting back to the normal setting. Note that the process in S008 may be performed before or simultaneously with the process in S007. The ink supply processing unit 82 will repeat the processes in S002 to S009 until the power to the printing device 100 is turned off. The ink supply processing unit 82 will also repeat the processes in S002 to S009 for each type of ink (for each system of the supply path 5C).

[0055] As described above, in this embodiment, the ink supply processing unit 82 increases the set temperature of the heating heater 51 in S003, and then drives the liquid transfer pump 5B in S005 to supply ink to the damper 60. If the set temperature of the heating heater 51 is increased after the liquid transfer pump 5B has started to drive, ink may flow into the heating channel 54 of the heating unit 50 before the heating heater 51 rises from the normal setting Tp (e.g., 35°C) to the heating setting Tmax (e.g., 50°C), and there is a risk that ink that has not been heated to the predetermined temperature will be supplied to the damper 60. In particular, under circumstances where the output of the heating heater 51 is limited, if ink flows into the heating channel 54 when the heating heater 51 is at the normal setting which is lower than the heating setting, it becomes easier for ink that has not been heated to the predetermined temperature to be supplied to the damper 60. In contrast, in this embodiment, since the liquid transfer pump 5B is driven after the set temperature of the heating heater 51 is increased, it is possible to suppress the supply of unheated ink to the damper 60 compared to the case where the set temperature of the heating heater 51 is increased after the driving of the liquid transfer pump 5B is started.

[0056] <Example 1> Figure 8 is an explanatory diagram of the damper 60 of the first modified example. Note that the ink volume detection unit 65 (lever 651; see Figures 4 to 6) is not shown in Figure 8.

[0057] In the first modified example, the damper 60 also comprises a main body case 61, a damper membrane 62, a spring 63, and a pressure receiving plate 64. The damper 60 of the first modified example is equipped with a damper heater 66. The damper heater 66 is a heat source for heating the ink stored in the damper 60. By equipping the damper 60 with a damper heater 66, the cooling of the ink can be suppressed. The damper heater 66 functions as a heat-retaining heater that maintains the temperature of the ink. The damper heater 66 is provided in the main body case 61.

[0058] Alternatively, the ink temperature may be heated from Ta to Tp using the damper heater 66. If the ink temperature is heated from Ta to Tp using the damper heater 66, the printing apparatus 100 does not need to be equipped with a heating unit 50. However, if the printing apparatus 100 is equipped with a heating unit 50, the damper heater 66 only needs to maintain the ink heated by the heating unit 50 at a predetermined temperature, and therefore can be configured with a heater with low output.

[0059] Figure 9 is an explanatory diagram of the damper 60 of the second modified example.

[0060] In the second modified example, the damper 60 also comprises a main body case 61, a damper film 62, a spring 63, and a pressure receiving plate 64. The damper 60 of the second modified example is equipped with a heat conductor 67. The heat conductor 67 is a component that transfers heat to the ink stored in the damper 60. Here, one end of the heat conductor 67 is connected to a damper heater 66, and it has the function of transferring heat from the damper heater 66 to the ink. By transferring heat from the damper heater 66 to the ink via the heat conductor 67, the degree of freedom in the placement of the damper heater 66 can be increased. The heat conductor 67 is made of a film-like material with high thermal conductivity. The heat conductor 67 is made of a material with higher thermal conductivity than the damper film 62. The heat conductor 67 may also be made of a film-like heater. In this case, the heat conductor 67 functions as a damper heater.

[0061] The heat conductor 67 is provided on the surface of the damper film 62. In the second modified example, where the ink is heated by the heat conductor 67 provided on the damper film 62, the structure is more efficient at transferring heat to the ink compared to the first modified example, where the ink is heated by a damper heater 66 provided on the main body case 61, because it is not affected by the thermal resistance of the main body case 61.

[0062] The heat conductor 67, like the damper film 62, is made of an elastically deformable material. As a result, even though the heat conductor 67 is provided on the damper film 62, the damper film 62 can change its deflection according to the amount of ink in the damper 60.

[0063] The heat conductor 67 shown in Figure 9 is composed of narrow, strip-shaped (tape-shaped, ribbon-shaped) members. Furthermore, the heat conductor 67 is arranged radially from the center of the circular pressure plate 64. This suppresses tilting of the pressure plate 64 when the damper film 62 flexes and deforms in accordance with the amount of ink, causing the pressure plate 64 to be displaced.

[0064] As shown in Figure 9, the damper membrane 62 is configured to cover the rectangular opening of the main body case 61, and the heat conductors 67 are arranged radially from the center of the circular pressure plate 64 along the diagonals of the rectangular opening. This makes it easier to suppress tilting of the pressure plate 64. Note that the radially arranged heat conductors 67 are not limited to being arranged to spread in four directions as shown in Figure 9, but may also be arranged to spread in eight directions, for example.

[0065] Figure 10 is an explanatory diagram of another form of the heat conductor 67 in the second modified example.

[0066] In Figure 10, the heat conductor 67 is composed of a narrow, strip-shaped (tape-shaped, ribbon-shaped) member. The heat conductor 67 shown in Figure 10 is arranged in a spiral shape. This prevents the pressure plate 64 from tilting when the damper film 62 flexes and deforms in accordance with the amount of ink, causing the pressure plate 64 to be displaced. Furthermore, by making the heat conductor 67 spiral-shaped, the surface area of ​​the heat conductor 67 can be increased, resulting in a structure that easily transfers heat to the ink.

[0067] <Modification 2> If the ink is white or silver, there is a risk that the pigment in the ink may settle. Therefore, the ink supply unit 5, which will be described next, is capable of circulating the ink in order to suppress the settling of the pigment.

[0068] Figure 11 is an explanatory diagram of a modified ink supply unit 5.

[0069] In the modified version, the ink supply unit 5 includes a liquid transfer pump 5B, a heating unit 50, a damper 60, and a heat retention unit 70. The modified version of the ink supply unit 5 is also provided with an on / off valve 91, a recovery path 92, a recovery pump 93, and a heat exchange section 95.

[0070] The on / off valve 91 is a valve for opening and closing the ink supply passage 5C. The on / off valve 91 is located at the supply port of the ink cartridge 5A and is situated between the ink cartridge 5A and the liquid transfer pump 5B. The on / off valve 91 is also located upstream in the liquid transfer direction from the confluence section 922 where the supply passage 5C and the recovery passage 92 merge. The on / off valve 91 can be controlled by the controller 80 to open and close the supply passage 5C.

[0071] The recovery path 92 is a passage for sending the recovered ink. The recovery path 92 is the ink passage between the branching section 921 and the confluence section 922. The branching section 921 is the point where the ink flow branches off from the supply path 5C between the heating unit 50 and the damper 60. The confluence section 922 is the point where the ink from the recovery path 92 merges with the supply path 5C. The recovery path 92 is a passage for sending the ink recovered at the branching section 921 (ink heated by the heating unit) to the confluence section 922. The supply path 5C between the confluence section 922 and the branching section 921, and the recovery path 92 between the branching section 921 and the confluence section 922, constitute the ink circulation path (see Figure 12B below).

[0072] The recovery pump 93 is a component for sending ink from the branching section 921 towards the merging section 922. In other words, the recovery pump 93 is a component for sending ink through the recovery path 92. The recovery pump 93 can be driven and stopped by the controller 80.

[0073] Figure 12A is an explanatory diagram illustrating how ink is sent from the ink cartridge 5A to the print head 10. As shown in Figure 12A, the controller opens the on / off valve 91, drives the liquid transfer pump 5B, and stops the recovery pump 93. This causes the ink to be sent from the ink cartridge 5A to the print head 10.

[0074] Figure 12B is an explanatory diagram of how the ink is circulated. As shown in Figure 12B, the controller closes the on / off valve 91 and drives the liquid supply pump 5B and the recovery pump 93. As a result, ink is sent from the junction 922 to the branching section 921 in the supply path 5C, and ink is sent from the branching section 921 to the junction 922 in the recovery path 92, thereby circulating the ink.

[0075] Figure 13 is an explanatory diagram of the heat exchange section 95.

[0076] The heat exchange unit 95 exchanges thermal energy between the ink in the supply path 5C and the ink in the recovery path 92. The supply path 5C and the recovery path 92 are arranged side by side in the heat exchange unit 95. The heat exchange unit 95 supports the supply path 5C and the recovery path 92 in parallel. Here, the heat exchange unit 95 has an insulating case 95A that covers the supply path 5C and the recovery path 92, and the insulating case 95A functions as a support that supports the supply path 5C and the recovery path 92 in parallel. By covering the supply path 5C and the recovery path 92 with the insulating case 95A, the efficiency of transferring heat from the ink in the recovery path 92 (ink heated by the heating unit 50) to the ink in the supply path 5C can be increased. Note that the supply path 5C and the recovery path 92 do not necessarily have to be supported in parallel by the insulating case 95A, and the supply path 5C and the recovery path 92 do not necessarily have to be covered by the insulating case 95A. For example, the supply passage 5C and the recovery passage 92, which are made of tubes, may be supported in parallel by clamps (corresponding to support parts). Alternatively, the supply passage 5C and the recovery passage 92 may be made of connecting tubes, thereby forming a heat exchange section 95 in which the supply passage 5C and the recovery passage 92 are arranged in parallel.

[0077] In the heat exchange section 95, the direction of ink flow in the supply path 5C (liquid delivery direction) and the direction of ink flow in the recovery path 92 (recovery direction) are reversed. Since the ink in the recovery path 92 is hotter upstream in the recovery direction (closer to the branching section 921), the ink in the supply path 5C in the heat exchange section 95 is hotter downstream in the liquid delivery direction (closer to the heating unit 50) due to the heat from the ink in the recovery path 92. By reversing the direction of ink flow in the supply path 5C and the recovery path 92 in the heat exchange section 95, the efficiency of heat exchange can be increased. This makes it possible to increase the temperature of the ink supplied to the heating unit 50 and suppress the supply of unheated ink to the damper 60.

[0078] <Summary> The above-described printing apparatus 100 includes a head 10 that ejects ink onto a medium M, a damper 60 that stores ink and supplies ink to the head 10, a heating unit 50 that heats the ink with a heating heater 51 upstream of the damper 60 in the ink supply direction, and a controller 80 that supplies ink from the heating unit 50 to the damper 60 after the heating heater 51 has been raised (S003). This makes it possible to suppress the supply of unheated ink to the damper 60 compared to the case where the set temperature of the heating heater 51 is raised after the ink supply has started.

[0079] As shown in Figure 3, the print head 10 is capable of ejecting multiple types of ink, and a heating unit 50 is provided for each type of ink. This makes it possible to heat each ink according to its consumption, even if the amount of ink consumed during the printing process differs for each type of ink. However, a common heating unit may be provided for each of the two ink supply paths 5C, and both types of ink may be heated by the common heating unit. Even in this case, by supplying ink from the heating unit 50 to the damper 60 after raising the temperature of the heating heater 51 (S003), it is possible to suppress the supply of unheated ink to the damper 60.

[0080] As shown in Figure 3, the heating unit 50 is housed in an insulated case 55. This helps to suppress the temperature drop of the ink in the heating unit 50.

[0081] The controller 80 is configured to supply ink from the heating unit 50 to the damper 60 after raising the temperature of the heating heater 51 (S003) when it determines, based on the detection result of the ink amount detection unit 65, that the amount of ink in the damper 60 has fallen below a predetermined value (YES in S002). When supplying ink to the damper 60 in this way when the ink in the damper 60 decreases, the ink flow rate at the time of supply is relatively fast, but by supplying ink from the heating unit 50 to the damper 60 after raising the temperature of the heating heater 51 (S003), it is possible to suppress the supply of unheated ink to the damper 60.

[0082] A heat retention unit 70 is provided downstream of the heating unit 50 in the liquid delivery direction. In this embodiment, when the heating unit 50 is positioned upstream of the damper 60 in the liquid delivery direction, there is a risk that the ink heated by the heating unit 50 will cool down before it is ejected from the head 10. Therefore, providing a heat retention unit 70 in such cases is particularly effective.

[0083] As shown in Figure 3, dampers 60 are provided for each type of ink, and the heat retention unit 70 has an insulating case 72 that houses multiple dampers 60. By housing multiple dampers 60 in a common insulating case 72, the structure of the heat retention unit 70 can be simplified.

[0084] As shown in Figures 8 to 10, the damper 60 may have a damper heater 66 that heats the ink stored inside. This prevents the ink heated by the heating unit 50 from cooling down.

[0085] Furthermore, as shown in Figures 9 and 10, it is desirable that a heat conductor 67 be provided on the damper membrane 62 of the damper 60. This creates a structure that facilitates heat transfer to the ink stored inside the damper 60.

[0086] The heat conductor 67 shown in Figures 9 and 10 is connected to the damper heater 66 and conducts heat from the damper heater 66 to the ink. This increases the flexibility of the placement of the damper heater 66. However, the heat conductor 67 may also be composed of the damper heater. This reduces the number of parts in the damper 60.

[0087] As shown in Figure 9, it is preferable that the heat conductor 67 be arranged radially from the center of the circular pressure plate. Alternatively, as shown in Figure 10, it is preferable that the heat conductor 67 be arranged in a spiral shape. This makes it possible to suppress the tilting of the pressure plate 64 when the damper film 62 bends and deforms in accordance with the amount of ink, causing the pressure plate 64 to be displaced. Furthermore, as shown in Figure 10, when the heat conductor 67 is arranged in a spiral shape, it becomes easier to increase the surface area of ​​the heat conductor 67, resulting in a structure that facilitates heat transfer to the ink.

[0088] As shown in Figure 11, it is desirable that a recovery path 92 be provided between a branching section 921 located downstream of the heating unit 50 in the liquid delivery direction and a confluence section 922 located upstream of the heating unit 50 in the liquid delivery direction. This makes it possible to circulate the ink, as shown in Figure 12B, and suppresses the sedimentation of the ink pigment.

[0089] Furthermore, as shown in Figures 11 and 13, it is desirable to provide a heat exchange section 95. This allows the temperature of the ink supplied to the heating unit 50 to be increased, and prevents unheated ink from being supplied to the damper 60.

[0090] Furthermore, as shown in Figure 13, it is desirable that in the heat exchange section 95, the direction of ink flow in the supply path 5C (liquid delivery direction) and the direction of ink flow in the recovery path 92 (recovery direction) are opposite. This can improve the efficiency of heat exchange.

[0091] ===Other Embodiments=== The above embodiments are presented as examples and do not limit the scope of the invention. The above configurations can be combined as appropriate, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. The above embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0092] 5. Ink supply unit, 5A ink cartridge, 5B Liquid transfer pump, 5C Supply path, 10 heads, 20 carriage units, 21 carriage, 22 carriage motor, 30 Conveying unit, 31 Conveying component, 32 Conveying motor, 40 Irradiation unit, 41 Light source, 50 heating unit, 51 heating heater, 52 supply port, 53 discharge port, 54 Heating channel, 55 Insulated case, 60 dampers, 61 main case, 61A inlet, 61B outlet, 62 Damper membrane, 63 Spring, 64 Pressure plate, 65 Ink volume detection unit, 651 Lever, 652 Sensor, 66 Heater for damper, 67 Heat conductor, 70 Insulation unit, 71 Insulation heater, 72 Insulated case, 73 Temperature sensor, 80 controllers, 81 Printing processing unit, 82 Ink supply processing unit, 91 On / off valve, 92 Recovery path, 921 Branching point, 922 Confluence point, 93 Recovery pump, 95 Heat exchanger, 95A Insulated case, 100 Printing device, M media

Claims

1. A head that ejects ink onto the medium, A damper that stores the ink and supplies the ink to the head, A heating unit that heats the ink with a heating heater upstream of the damper in the direction of ink flow, A controller that supplies the ink from the heating unit to the damper after raising the temperature of the heating heater, A printing device equipped with the following features.

2. A printing apparatus according to claim 1, The aforementioned head is capable of ejecting multiple types of ink, The printing apparatus is characterized in that the heating unit is provided for each type of ink.

3. A printing apparatus according to claim 1 or 2, The printing apparatus is characterized in that the heating unit is housed in an insulated case.

4. A printing apparatus according to claim 1 or 2, The damper has an ink amount detection unit that detects the amount of ink, The printing apparatus is characterized in that, when the controller determines, based on the detection result of the ink amount detection unit, that the amount of ink in the damper has fallen below a predetermined value, it raises the temperature of the heating heater and then supplies the ink from the heating unit to the damper.

5. A printing apparatus according to claim 1 or 2, A printing apparatus characterized in that a heat retention unit for maintaining the temperature of the ink is provided downstream of the heating unit in the liquid delivery direction.

6. A printing apparatus according to claim 5, The damper is provided for each type of ink, The printing apparatus is characterized in that the heat retention unit has an insulating case that houses a plurality of dampers.

7. A printing apparatus according to claim 1 or 2, The printing apparatus is characterized in that the damper has a damper heater for heating the ink stored inside.

8. A printing apparatus according to claim 7, The damper comprises a main body case having an opening and a damper membrane covering the opening. The printing apparatus is characterized in that the damper membrane is provided with a heat conductor that conducts heat to the ink.

9. A printing apparatus according to claim 8, The printing apparatus is characterized in that the heat conductor is connected to the damper heater and conducts the heat from the damper heater to the ink.

10. A printing apparatus according to claim 8, The printing apparatus is characterized in that the heat conductor is composed of the damper heater.

11. A printing apparatus according to claim 8, The damper comprises a spring and a pressure plate that presses against the damper membrane with the force of the spring. The pressure receiving plate is a circular member, The printing apparatus is characterized in that the heat conductors are arranged radially from the center of the pressure plate.

12. A printing apparatus according to claim 8, The damper comprises a spring and a pressure plate that presses against the damper membrane with the force of the spring. The pressure receiving plate is a circular member, The printing apparatus is characterized in that the heat conductor is arranged in a spiral shape.

13. A printing apparatus according to claim 1 or 2, A branching section is provided downstream of the heating unit in the direction of ink delivery, which branches the ink from the supply path through which the ink flows toward the head. Upstream of the heating unit in the liquid delivery direction, a confluence section is provided to merge the ink into the supply path. A printing apparatus characterized in that a recovery path for sending the ink from the branching section toward the merging section is provided between the branching section and the merging section.

14. A printing apparatus according to claim 13, A printing apparatus characterized by having a heat exchange section provided where heat is exchanged between the ink in the supply path and the ink in the recovery path, located upstream of the heating unit in the liquid delivery direction.

15. A printing apparatus according to claim 14, In the heat exchange section, the supply path and the recovery path are arranged in parallel. A printing apparatus characterized in that the direction of ink flow in the supply path and the direction of ink flow in the recovery path are opposite.

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