Stereolithography apparatus

Abstract

A three-dimensional object printing apparatus capable of reducing variation in ink ejection characteristics in an inkjet head. The three-dimensional object printing apparatus has: a base; an arm supported by the base; a liquid ejection head fixed at a top end of the arm and ejecting a liquid toward a workpiece; a liquid storage portion storing the liquid; a supply flow path communicating the liquid storage portion and the liquid ejection head and supplying the liquid from the liquid storage portion to the liquid ejection head; and a pressure adjustment valve provided midway in the supply flow path and adjusting the pressure of the liquid supplied to the liquid ejection head. The arm has N (N ≥ 3) movable portions that three-dimensionally change the position and posture of the liquid ejection head. The pressure adjustment valve is fixed to the arm.

Description

Technical Field

[0001] This invention relates to a three-dimensional printing apparatus. Background Technology

[0002] A three-dimensional printing apparatus is known for printing on the surface of a three-dimensional object by inkjet printing. For example, the apparatus described in Patent Document 1 includes: an inkjet head that ejects ink; a robotic arm capable of changing the ejection direction of the ink by the inkjet head; and an ink tank that supplies ink to the inkjet head.

[0003] In the device described in Patent Document 1, a pressure corresponding to the water level difference between the ink in the inkjet head and the ink in the ink tank is applied to the ink inside the inkjet head. Therefore, in the device described in Patent Document 1, as the vertical positional relationship between the inkjet head and the ink tank changes, the pressure of the ink inside the inkjet head changes, resulting in a problem where the ejection characteristics of the ink in the inkjet head change.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2016-175358 Summary of the Invention

[0005] To address the above-mentioned issues, one embodiment of the stereolithography printing apparatus according to the present invention is a stereolithography printing apparatus comprising: a base; an arm supported by the base; a liquid ejector head fixed to the top end of the arm and ejecting liquid onto a workpiece; a liquid storage section for storing liquid; a supply channel connecting the liquid storage section and the liquid ejector head and supplying liquid from the liquid storage section to the liquid ejector head; and a pressure regulating valve disposed in the middle of the supply channel for adjusting the pressure of the liquid supplied to the liquid ejector head. The arm has N (N≥1) movable parts that allow the angle of the liquid ejector head relative to a horizontal plane to change. The pressure regulating valve is fixed to the arm, and K (1≤K≤N) of the movable parts are disposed between the pressure regulating valve and the base. Attached Figure Description

[0006] Figure 1 A perspective view showing the outline of the three-dimensional printing apparatus according to the first embodiment.

[0007] Figure 2 This is a block diagram illustrating the electrical structure of the three-dimensional printing apparatus according to the first embodiment.

[0008] Figure 3 This is a perspective view showing the outline structure of the liquid ejector head unit in the first embodiment.

[0009] Figure 4This is a cross-sectional view showing an example of the structure of the liquid ejector head in the first embodiment.

[0010] Figure 5 This is a plan view showing an example of the structure of the pressure regulating valve in the first embodiment.

[0011] Figure 6 for Figure 5 Sectional view along line AA in the diagram.

[0012] Figure 7 This diagram illustrates the change in the positional relationship between the liquid nozzle and the pressure regulating valve.

[0013] Figure 8 This is a diagram illustrating an example of multiple drive signals that include different drive pulses.

[0014] Figure 9 This is a flowchart illustrating the operation of the three-dimensional printing apparatus according to the second embodiment.

[0015] Figure 10 A diagram illustrating the pressure distribution of ink within a nozzle array.

[0016] Figure 11 A flowchart illustrating the operation of the three-dimensional printing apparatus according to the third embodiment.

[0017] Figure 12 This is a schematic diagram illustrating the three-dimensional printing apparatus according to the fourth embodiment.

[0018] Figure 13 This diagram illustrates the change in the positional relationship between the liquid nozzle and the pressure regulating valve in the comparative example. Detailed Implementation

[0019] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the dimensions or scales of various parts in the drawings differ appropriately from actual dimensions, and some parts are shown schematically for ease of understanding. Furthermore, unless otherwise specified in the following description, the scope of the present invention is not limited to these embodiments.

[0020] Furthermore, the following explanation appropriately uses intersecting X-axis, Y-axis, and Z-axis. Additionally, a direction along the X-axis will be referred to as the X1 direction, and the opposite direction will be referred to as the X2 direction. Similarly, opposite directions along the Y-axis will be referred to as the Y1 and Y2 directions. Furthermore, opposite directions along the Z-axis will be referred to as the Z1 and Z2 directions.

[0021] Here, the Z-axis is the vertical axis, and the Z2 direction corresponds to the downward direction in the vertical direction. Therefore, the X-axis and Y-axis are axes along the horizontal plane. In addition, although the X-axis, Y-axis and Z-axis are typically orthogonal to each other, this is not a limitation; for example, they can intersect at an angle between 80° and 100°.

[0022] 1. First Implementation Method

[0023] 1-1. Overview of a 3D printing apparatus

[0024] Figure 1 This is a perspective view showing the outline of the three-dimensional printing apparatus 100 according to the first embodiment. The three-dimensional printing apparatus 100 is an apparatus that performs printing on the surface of a workpiece W, which is an example of a three-dimensional object, by inkjet printing. Figure 1 In the example shown, workpiece W has mutually orthogonal surfaces WF1 and WF2. Surface WF1 is a plane facing the Z1 direction. Surface WF2 is a plane facing the X1 direction. Furthermore, the shape of workpiece W is not limited to... Figure 1 The example shown is not arbitrary.

[0025] exist Figure 1 In the example shown, the stereoscopic printing apparatus 100 is an inkjet printer using a vertical multi-joint robot. Specifically, as Figure 1 As shown, the stereolithography printing apparatus 100 includes: a robot 200, a liquid ejector unit 300, a liquid storage unit 400, a supply channel 500, and a control device 600. Hereinafter, each part of the stereolithography printing apparatus 100 will be briefly described in turn.

[0026] Robot 200 is a so-called 6-axis vertical articulated robot. Specifically, robot 200 has a base 210 and an arm 220.

[0027] The base 210 is a platform that supports the arm 220. Figure 1 In the example shown, the base 210 is fixed to a mounting surface such as a floor surface facing the Z1 direction by means of threaded fastening or the like. Furthermore, the mounting surface of the fixed base 210 can be a surface facing any direction and is not limited to any particular direction. Figure 1 The examples shown could also be surfaces such as walls, ceilings, movable trolleys, etc.

[0028] Arm 220 is a six-axis robotic arm having a base end mounted on a base 210 and a tip end that allows the position and posture to change three-dimensionally relative to the base end. Specifically, arm 220 has arms 221, 222, 223, 224, 225, and 226, which are connected in this order.

[0029] Arm 221 is rotatably connected to base 210 about a first rotation axis O1 via joint 231. Arm 222 is rotatably connected to arm 221 about a second rotation axis O2 via joint 232. Arm 223 is rotatably connected to arm 222 about a third rotation axis O3 via joint 233. Arm 224 is rotatably connected to arm 223 about a fourth rotation axis O4 via joint 234. Arm 225 is rotatably connected to arm 224 about a fifth rotation axis O5 via joint 235. Arm 226 is rotatably connected to arm 225 about a sixth rotation axis O6 via joint 236.

[0030] Here, joints 231 to 236 are examples of movable parts. Figure 1 In the example shown, joints 231 to 236 are mechanisms that connect one of two adjacent arms in a rotatable manner relative to the other. Although not shown, each of joints 231 to 236 is provided with a drive mechanism for rotating one of the two adjacent arms relative to the other. This drive mechanism includes, for example, a motor that generates a driving force for the rotation; a reducer that reduces the driving force and outputs it; and an encoder such as a rotary encoder that detects the angle of rotation, etc. Furthermore, this drive mechanism corresponds to the mechanism described later... Figure 2 The arm drive mechanism 230 shown is illustrated.

[0031] The first rotation axis O1 is perpendicular to a not shown mounting surface of the fixed base 210. The second rotation axis O2 is perpendicular to the first rotation axis O1. The third rotation axis O3 is parallel to the second rotation axis O2. The fourth rotation axis O4 is perpendicular to the third rotation axis O3. The fifth rotation axis O5 is perpendicular to the fourth rotation axis O4. The sixth rotation axis O6 is perpendicular to the fifth rotation axis O5.

[0032] Furthermore, for these rotation axes, "perpendicular" includes not only the case where the angle between the two rotation axes is strictly 90°, but also the case where the angle between the two rotation axes deviates from 90° within a range of approximately ±5°. Similarly, "parallel" includes not only the case where the two rotation axes are strictly parallel, but also the case where one of the two rotation axes is tilted relative to the other within a range of approximately ±5°.

[0033] At the top of the arm 221 above, i.e. on the arm 226, a liquid ejector head unit 300 is installed as an end effector.

[0034] The liquid ejector unit 300 has a mechanism that ejects ink, an example of liquid, toward the workpiece W from a liquid ejector head 310. In this embodiment, in addition to the liquid ejector head 310, the liquid ejector unit 300 also includes a pressure regulating valve 320 for adjusting the pressure of the ink supplied to the liquid ejector head 310 and a displacement sensor 330 for measuring the distance between itself and the workpiece W. Since these are fixed together on the arm 226, their relative positions and orientations are fixed.

[0035] The liquid nozzle 310 and pressure regulating valve 320 will be described in detail later. The displacement sensor 330 is, for example, an optical displacement sensor that measures the amount of displacement when moving from one position to another. Furthermore, the displacement sensor 330 can be omitted as long as it is set as needed. Additionally, although in Figure 1 In the example shown, the liquid ejector unit 300 has one liquid ejector head 310 and one pressure regulating valve 320, but this number is not limited to one. Figure 1 The example shown can also have more than two.

[0036] The liquid storage section 400 is a container for storing ink. The liquid storage section 400 is, for example, a bag-shaped ink can formed from a flexible film. The ink stored in the liquid storage section 400 is, for example, ink containing color materials such as dyes or pigments. Furthermore, the type of ink stored in the liquid storage section 400 is not limited to inks containing color materials; for example, it may also be ink containing conductive materials such as metal powder. In addition, the ink may have curable properties such as UV curability. When the ink has curable properties such as UV curability, for example, an ultraviolet irradiation mechanism is mounted on the liquid ejector unit 300.

[0037] exist Figure 1 In the example shown, the liquid reservoir 400 is fixed to a wall, ceiling, or column in a manner that always positions it further along the Z1 direction than the liquid nozzle 310. That is, the liquid reservoir 400 is located higher in the vertical direction than the moving area of ​​the liquid nozzle 310. Therefore, even without using a pump or similar mechanism, ink can be supplied from the liquid reservoir 400 to the liquid nozzle 310 with a predetermined pressure.

[0038] Furthermore, the location of the liquid storage unit 400 can be such that ink can be supplied from the liquid storage unit 400 to the liquid nozzle 310 at a predetermined pressure, or it can be located at a position lower in the vertical direction than the liquid nozzle 310. In this case, for example, as in the fourth embodiment described later, ink can be supplied from the liquid storage unit 400 to the liquid nozzle 310 at a predetermined pressure using a pump.

[0039] The supply channel 500 is a channel for supplying ink from the liquid storage section 400 to the liquid nozzle 310. A pressure regulating valve 320 is provided midway through the supply channel 500. Therefore, even if the positional relationship between the liquid nozzle 310 and the liquid storage section 400 changes, the pressure fluctuation of the ink in the liquid nozzle 310 can be reduced.

[0040] The supply channel 500 is divided into an upstream channel 510 and a downstream channel 520 by a pressure regulating valve 320. That is, the supply channel 500 has an upstream channel 510 that connects the liquid storage section 400 and the pressure regulating valve 320 and a downstream channel 520 that connects the pressure regulating valve 320 and the liquid nozzle 310.

[0041] The upstream flow channel 510 and the downstream flow channel 520 are each formed, for example, by the internal space of a tube. Here, the tube for the upstream flow channel 510 is made of an elastic material such as rubber or an elastomer, and is flexible. Thus, by using a flexible tube to construct the upstream flow channel 510, changes in the relative positional relationship between the liquid storage section 400 and the pressure regulating valve 320 can be allowed. Therefore, while keeping the position and orientation of the liquid storage section 400 fixed, ink can be supplied from the liquid storage section 400 to the pressure regulating valve 320 even if the position or orientation of the liquid nozzle 310 changes. On the other hand, the tube for the downstream flow channel 520 may not be flexible. Therefore, the tube for the downstream flow channel 520 can be made of either an elastic material such as rubber or an elastomer, or a rigid material such as resin.

[0042] Additionally, a portion of the upstream flow channel 510 may also be constructed from a non-flexible component. Furthermore, the downstream flow channel 520 is not limited to a tube-like structure. For example, a portion or all of the downstream flow channel 520 may be a structure having a distribution channel for distributing ink from the pressure regulating valve 320 to multiple locations, or it may be integrally formed with the liquid nozzle 310 or the pressure regulating valve 320.

[0043] The control device 600 is a device for controlling the driving of each part of the stereolithography printing apparatus 100. The control device 600 will be described in detail along with the following description of the electrical structure of the stereolithography printing apparatus 100.

[0044] 1-2. Electrical Structure of the Three-Dimensional Printing Apparatus

[0045] Figure 2 This is a block diagram illustrating the electrical structure of the three-dimensional printing apparatus 100 according to the first embodiment. Figure 2 The electrical structural elements of the three-dimensional printing apparatus 100 are shown in the diagram. For example... Figure 2 As shown, the control device 600 includes a processing circuit 610, a storage circuit 620, a power supply circuit 630, and a drive signal generation circuit 640.

[0046] The processing circuit 610 has the functions of controlling the operation of various parts of the stereolithography printing apparatus 100 and processing various data. The processing circuit 610 may include, for example, one or more processors such as CPUs (Central Processing Units). Alternatively, the processing circuit 610 may replace a CPU or include a programmable logic device such as an FPGA (field-programmable gate array) in addition to a CPU. Furthermore, the hardware structure included in the control device 600 can be appropriately divided. For example, there are cases where the arm control unit 612 and the drive signal generation circuit 640 of the control device 600 are separately set in different hardware structures. Moreover, some or all of the functions of the control device 600 can be implemented through an external device connected to the stereolithography printing apparatus 100 via a network such as a LAN (Local Area Network) or the Internet.

[0047] The storage circuit 620 stores various programs, such as program P, executed by the processing circuit 610, and various data, such as printed data Img, processed by the processing circuit 610. The storage circuit 620 may include, for example, a semiconductor memory comprising one or both of the following: volatile memory such as RAM (Random Access Memory) and non-volatile memory such as ROM (Read Only Memory), EEPROM (Electrically Erasable Programmable Read-only Memory), or PROM (Programmable ROM). The printed data Img is supplied from an external device 700, such as a personal computer. Alternatively, the storage circuit 620 may also be configured as part of the processing circuit 610.

[0048] The power supply circuit 630 receives power from a commercial power supply not shown and generates various predetermined potentials. These potentials are appropriately supplied to various parts of the stereolithography apparatus 100. For example, the power supply circuit 630 generates a power supply potential VHV and an offset potential VBS. The offset potential VBS is supplied to the liquid ejector head unit 300. Furthermore, the power supply potential VHV is supplied to the drive signal generation circuit 640.

[0049] The drive signal generation circuit 640 is a circuit that generates drive signals Com for driving the piezoelectric elements 311 (described later) of the liquid ejector head 310. Specifically, the drive signal generation circuit 640 includes, for example, a DA conversion circuit and an amplifier circuit. In the drive signal generation circuit 640, the DA conversion circuit converts the waveform specification signal dCom (described later) from the processing circuit 610 from a digital signal into an analog signal, and the amplifier circuit amplifies the analog signal using the power supply potential VHV from the power supply circuit 630, thereby generating the drive signal Com. Here, the signal of the waveform included in the drive signal Com that is actually supplied to the piezoelectric element 311 is the drive pulse PD.

[0050] In the control device 600 described above, the processing circuit 610 controls the operation of each part of the stereolithography printing apparatus 100 by executing the program P stored in the storage circuit 620. Specifically, the processing circuit 610 functions as an information acquisition unit 611, an arm control unit 612, and an ejection control unit 613 by executing the program P.

[0051] The information acquisition unit 611 acquires various information required for the operation of the robot 200 and the liquid ejector unit 300. Specifically, the information acquisition unit 611 acquires printing data Img from the external device 700, information D1 from the encoder included in the arm drive mechanism 230, and information D2 from the displacement sensor 330. In addition, the information acquisition unit 611 appropriately reads and acquires information stored in the storage circuit 620, and appropriately stores the acquired information in the storage circuit 620.

[0052] The arm control unit 612 controls the drive of the robot 200 based on information from the information acquisition unit 611. Specifically, the arm control unit 612 generates a control signal Sk based on the three-dimensional shape data of the workpiece W and the information D1 from the arm drive mechanism 230. The control signal Sk controls the drive of the motors included in the arm drive mechanism 230 to bring the liquid nozzle 310 to the desired position and posture. This three-dimensional shape data is, for example, included in the printed data Img, or obtained by measurement using a displacement sensor 330, etc. In addition, the correspondence between the information D1 and the position and posture of the liquid nozzle is obtained in advance through calibration, etc., and stored in the storage circuit 620. Then, the arm control unit 612 obtains information related to the actual position and posture of the liquid nozzle 310 based on the actual information D1 from the arm drive mechanism 230 and the correspondence. Based on this, control is performed using the information related to the position and posture. In addition, the arm control unit 612 can also use the information D2 from the displacement sensor 330 to appropriately adjust the control signal Sk so that the distance between the liquid nozzle 310 and the surface of the workpiece W is maintained within a predetermined range.

[0053] The ejection control unit 613 controls the drive of the liquid ejection head unit 300 based on information from the information acquisition unit 611. Specifically, the ejection control unit 613 generates a control signal SI and a waveform specification signal dCom based on the printed data Img. The control signal SI is a digital signal used to specify the operating state of the piezoelectric element 311 (described later) in the liquid ejection head 310. Here, the control signal SI may also include other signals such as a timing signal for specifying the driving timing of the piezoelectric element 311. This timing signal is generated, for example, based on information D1 from the encoder included in the arm drive mechanism 230. The waveform specification signal dCom is a digital signal used to specify the waveform of the drive signal Com.

[0054] 1-3. Liquid nozzle and pressure regulating valve

[0055] Figure 3 This is a perspective view showing the outline structure of the liquid ejector head unit 300 in the first embodiment.

[0056] The following explanation uses intersecting a-axis, b-axis, and c-axis appropriately. Furthermore, a direction along the a-axis is called the a1 direction, and the opposite direction is called the a2 direction. Similarly, opposite directions along the b-axis are called the b1 and b2 directions. Furthermore, opposite directions along the c-axis are called the c1 and c2 directions.

[0057] Here, the c-axis is an axis parallel to the aforementioned sixth rotation axis O6. Furthermore, while the a-axis, b-axis, and c-axis are typically orthogonal to each other, this is not a limitation; for example, they may intersect at angles between 80° and 100°.

[0058] As previously described, the liquid ejector unit 300 includes a liquid ejector head 310, a pressure regulating valve 320, and a displacement sensor 330. These are... Figure 3 The support body 350 is shown by the double-dotted line in the image.

[0059] The support 350 is made of, for example, a metallic material and is a solid rigid body. Furthermore, although in Figure 3 The support body 350 is flat and box-shaped, but the shape of the support body 350 is not particularly limited and is arbitrary.

[0060] The aforementioned support 350 is mounted on the top of the aforementioned arm 220, namely arm 226. Therefore, the liquid nozzle 310, the pressure regulating valve 320, and the displacement sensor 330 are each fixed to arm 226. In addition, "fixed" means that the relative position and posture of the two components are fixed, which includes not only the case where the two components are directly fixed, but also the case where the two components are fixed through other components.

[0061] exist Figure 3 In the example shown, the pressure regulating valve 320 is located in the c1 direction relative to the liquid nozzle 310. The displacement sensor 330 is located in the a2 direction relative to the liquid nozzle 310.

[0062] exist Figure 3 In the example shown, a portion of the downstream flow channel 520 of the supply flow channel 500 is constituted by a flow channel component 521. The flow channel component 521 has flow channels for dispensing ink from the pressure regulating valve 320 to multiple portions of the liquid nozzle 310. The flow channel component 521 is, for example, a laminate of multiple substrates made of a resin material, and grooves or holes for ink flow channels are suitably provided on each substrate.

[0063] The liquid ejector head 310 has a nozzle face F and a plurality of nozzles N opening on the nozzle face F. Figure 3 In the example shown, the normal direction of the nozzle surface F is the c2 direction, and the plurality of nozzles N are divided into a first nozzle column L1 and a second nozzle column L2 arranged at intervals along the a-axis. The first nozzle column L1 and the second nozzle column L2 are each a collection of a plurality of nozzles N arranged linearly along the b-axis. Here, the elements associated with each nozzle N in the first nozzle column L1 and the elements associated with each nozzle N in the second nozzle column L2 in the liquid ejector head 310 have a structure that is approximately symmetrical to each other along the a-axis.

[0064] However, the positions of the multiple nozzles N in the first nozzle array L1 and the multiple nozzles N in the second nozzle array L2 along the b-axis can be either the same or different. Furthermore, elements associated with each nozzle N in either the first nozzle array L1 or the second nozzle array L2 can be omitted. The following example illustrates a structure in which the multiple nozzles N in the first nozzle array L1 and the multiple nozzles N in the second nozzle array L2 are positioned in the same direction along the b-axis.

[0065] Figure 4 This is a cross-sectional view showing an example of the structure of the liquid ejector head 310 in the first embodiment. Figure 4 As shown, the liquid ejector head 310 includes: a flow channel substrate 312, a pressure chamber substrate 313, a nozzle plate 314, a vibration absorber 315, a vibrating plate 316, multiple piezoelectric elements 311, a wiring substrate 317, and a frame portion 318.

[0066] The flow channel substrate 312 and the pressure chamber substrate 313 form flow channels for supplying ink to a plurality of nozzles N. The flow channel substrate 312 and the pressure chamber substrate 313 are laminated in the c1 direction in this order. The flow channel substrate 312 and the pressure chamber substrate 313 are each a strip-shaped plate member in the direction along the b axis. The flow channel substrate 312 and the pressure chamber substrate 313 are bonded to each other, for example, by an adhesive.

[0067] A vibrating plate 316, a wiring board 317, a frame portion 318, and a drive circuit 340 are disposed in a region located further in the c1 direction than the pressure chamber substrate 313. On the other hand, a nozzle plate 314 and a vibration absorber 315 are disposed in a region located further in the c2 direction than the flow channel substrate 312. These elements are generally similar to the flow channel substrate 312 and the pressure chamber substrate 313, being elongated plate-shaped members in the direction along the b-axis, and are joined together, for example, by an adhesive.

[0068] The nozzle plate 314 is a plate-shaped component having a plurality of nozzles N. Each nozzle N is a circular through-hole through which ink passes. Here, the surface of the nozzle plate 314 facing the c2 direction is the aforementioned nozzle surface F. The nozzle plate 314 is manufactured, for example, by processing a single-crystal silicon substrate using semiconductor manufacturing techniques such as dry etching or wet etching. However, other known methods and materials may also be appropriately used in the manufacture of the nozzle plate 314.

[0069] On the flow channel substrate 312, a space Ra, a plurality of supply channels 312a, a plurality of connecting channels 312b, and a supply liquid chamber 312c are respectively provided for each of the first nozzle array L1 and the second nozzle array L2. The space Ra is an elongated opening extending along the b-axis when viewed in a planar view along the c-axis direction. The supply channels 312a and connecting channels 312b are through holes formed for each nozzle N. The supply liquid chamber 312c is an elongated space extending along the b-axis across the plurality of nozzles N, and the space Ra and the plurality of supply channels 312a are interconnected. Each of the plurality of connecting channels 312b overlaps with a corresponding nozzle N when viewed in a planar view.

[0070] The pressure chamber substrate 313 is a plate-shaped component having a plurality of pressure chambers Cv, referred to as chambers, formed for each of the first nozzle array L1 and the second nozzle array L2. The plurality of pressure chambers Cv are arranged in the direction along the b-axis. Each pressure chamber Cv is an elongated space formed for each nozzle N and extending in the direction along the a-axis when viewed in plan view. The flow channel substrate 312 and the pressure chamber substrate 313 are manufactured, for example, by processing a single-crystal silicon substrate using semiconductor manufacturing technology, similar to the aforementioned nozzle plate 314. However, other known methods and materials may be appropriately used in the manufacture of the flow channel substrate 312 and the pressure chamber substrate 313.

[0071] The pressure chamber Cv is the space located between the flow channel substrate 312 and the vibrating plate 316. For each nozzle row of the first nozzle row L1 and the second nozzle row L2, multiple pressure chambers Cv are arranged in the direction along the b-axis. Furthermore, the pressure chamber Cv is connected to the connecting flow channel 312b and the supply flow channel 312a, respectively. Therefore, the pressure chamber Cv is connected to the nozzle N via the connecting flow channel 312b, and to the space Ra via the supply flow channel 312a and the supply liquid chamber 312c.

[0072] A vibrating plate 316 is disposed on the surface of the pressure chamber substrate 313 facing the c2 direction. The vibrating plate 316 is a plate-shaped component capable of elastically vibrating. The vibrating plate 316 has, for example, an elastic film made of silicon oxide (SiO2) and an insulating film made of zirconium oxide (ZrO2), and these are laminated together. The elastic film is formed, for example, by thermal oxidation of one side of a single-crystal silicon substrate. The insulating film is formed, for example, by sputtering to form a zirconium layer and then thermally oxidizing that layer.

[0073] On the surface of the vibrating plate 316 facing the c1 direction, a plurality of piezoelectric elements 311 corresponding to each nozzle N are respectively arranged for each of the first nozzle array L1 and the second nozzle array L2. Each piezoelectric element 311 is a driven element that deforms upon supply of the aforementioned drive pulse PD. Each piezoelectric element 311 is an elongated strip extending along the a-axis when viewed in planar view. The plurality of piezoelectric elements 311 are arranged along the b-axis in a manner corresponding to a plurality of pressure chambers Cv. When the vibrating plate 316 vibrates in a manner that is linked to the deformation of the piezoelectric elements 311, the pressure in the pressure chambers Cv changes, thereby causing ink to be ejected from the nozzle N toward the c2 direction.

[0074] The frame portion 318 is a housing for storing ink supplied to multiple pressure chambers Cv. For example... Figure 4 As shown, in the frame portion 318 of this embodiment, spaces Rb are formed for the first nozzle array L1 and the second nozzle array L2, respectively. The spaces Rb of the frame portion 318 and the spaces Ra of the flow channel substrate 312 are interconnected. The space formed by the spaces Ra and Rb functions as a liquid storage chamber (reservoir) R for storing ink supplied to the multiple pressure chambers Cv. For the liquid storage chamber R, ink is supplied through the inlet 318a formed on the frame portion 318. The ink in the liquid storage chamber R is supplied to the pressure chambers Cv through the supply liquid chamber 312c and each supply flow channel 312a. The vibration absorber 315 is a flexible film (plastic substrate) constituting the wall of the liquid storage chamber R, and absorbs pressure fluctuations of the ink in the liquid storage chamber R.

[0075] The wiring board 317 is a plate-shaped component with wiring for electrically connecting the drive circuit 340 and a plurality of piezoelectric elements 311. The surface of the wiring board 317 facing the c2 direction is joined to the vibrating plate 316 via a plurality of conductive bumps T. On the other hand, the drive circuit 340 is mounted on the surface of the wiring board 317 facing the c1 direction.

[0076] The drive circuit 340 is an IC (Integrated Circuit) chip that outputs drive signals and reference voltages for driving each piezoelectric element 311. Specifically, under the control of the control device 600, the drive circuit 340 switches whether to supply the drive signal Com as a drive pulse PD for each of the plurality of piezoelectric elements 311.

[0077] Although not shown, the end of an external wiring that is electrically connected to the control device 600 is joined to the surface of the wiring board 317 facing the c1 direction. This external wiring is, for example, composed of connecting components such as FPC (Flexible Printed Circuits) or FFC (Flexible Flat Cable). Alternatively, the wiring board 317 may also be an FPC or FFC.

[0078] Figure 5 This is a plan view showing a structural example of the pressure regulating valve 320 in the first embodiment. Figure 6 for Figure 5 The diagram shows a cross-sectional view along line AA. The pressure regulating valve 320 is a valve mechanism that opens and closes according to the pressure of the ink within the liquid nozzle 310. Through this opening and closing, the pressure of the ink within the liquid nozzle 310 is maintained at a negative pressure within a predetermined range. Therefore, the meniscus of the ink formed in the nozzle N of the liquid nozzle 310 can be stabilized. As a result, air bubbles entering the nozzle N or ink overflowing from the nozzle N can be prevented.

[0079] like Figure 6 As shown, the pressure regulating valve 320 has a flow channel component 321, a sealing component 322, a sealing component 323, a valve body 324, a force-applying component 325, and a force-applying component 326.

[0080] The flow channel component 321 is a structure having a flow channel Q that connects the upstream flow channel 510 and the downstream flow channel 520 in the aforementioned supply flow channel 500. The flow channel component 321 is made of, for example, a resin material such as polypropylene, and is formed by injection molding or the like. Figure 5 As shown, a supply port P1 and a discharge port P2 are provided on the flow channel component 321. The supply port P1 and the discharge port P2 are connected via the flow channel Q. The supply port P1 is connected to the upstream flow channel 510. The discharge port P2 is connected to the downstream flow channel 520.

[0081] like Figure 6 As shown, the flow channel Q has an upstream liquid chamber Q1 and a downstream liquid chamber Q2. The upstream liquid chamber Q1 is a space that communicates with the aforementioned supply port P1 via a flow channel not shown. On the other hand, the downstream liquid chamber Q2 is a space that communicates with the aforementioned discharge port P2 via a flow channel not shown.

[0082] exist Figure 5 And in Figure 6In the example shown, the flow channel component 321 is shaped like a generally plate with either direction a1 or a2 defined as the thickness direction. The upstream liquid chamber Q1 and the downstream liquid chamber Q2 are arranged in the thickness direction of the flow channel component 321. Here, a recess 321a for forming the upstream liquid chamber Q1 is provided on the surface of the flow channel component 321 facing the a2 direction. On the other hand, a recess 321b for forming the downstream liquid chamber Q2 is provided on the surface of the flow channel component 321 facing the a1 direction.

[0083] The upstream liquid chamber Q1 and the downstream liquid chamber Q2 are each circular when viewed from a plane along the a1 or a2 direction. Figure 6 In the example shown, the area of ​​the downstream liquid chamber Q2 in planar view is larger than the area of ​​the upstream liquid chamber Q1 in planar view. Furthermore, the shape or size of the upstream liquid chamber Q1 and the downstream liquid chamber Q2 are not limited to... Figure 5 as well as Figure 6 The examples shown are arbitrary.

[0084] A valve seat 321c is provided between the upstream liquid chamber Q1 and the downstream liquid chamber Q2 in the flow channel component 321. The valve seat 321c is a partition wall separating the upstream liquid chamber Q1 and the downstream liquid chamber Q2, and forms the bottom of the aforementioned recesses 321b and 321a. In other words, the valve seat 321c divides the flow channel Q into the upstream liquid chamber Q1 and the downstream liquid chamber Q2. A hole 321d is provided on the valve seat 321c. The hole 321d extends in the a1 direction or the a2 direction and connects the upstream liquid chamber Q1 and the downstream liquid chamber Q2.

[0085] The sealing component 322 is a component that is joined to the flow channel component 321 by welding or bonding to seal the opening of the aforementioned recess 321a. The sealing component 322 is made of a resin material such as polypropylene (PP) or polyphenylene sulfide (PPS). The sealing component 322 has a portion 322a that forms part of the wall of the upstream liquid chamber Q1. The rigidity of the portion 322a is higher than the rigidity of the sealing component 322. Preferably, the portion 322a has a rigidity to a degree that will not actually deform due to pressure variations of the ink within the upstream liquid chamber Q1.

[0086] The sealing member 323 is a sheet-like component that is joined to the flow channel component 321 by welding or bonding to seal the opening of the aforementioned recess 321b. The sealing member 323 is made of a resin material such as polypropylene (PP) or polyphenylene sulfide (PPS). The sealing member 323 has a flexible portion 323a that forms part of the wall of the downstream liquid chamber Q2. The flexible portion 323a is flexible enough to flex and deform according to the pressure of the ink in the downstream liquid chamber Q2.

[0087] Here, the flexible portion 323a separates the atmospheric open space from the downstream liquid chamber Q2. Within the flexible portion 323a, the pressure of the ink within the downstream liquid chamber Q2 becomes lower than atmospheric pressure, thereby applying a force towards the downstream liquid chamber Q2. Figure 6 In the example shown, a pressure plate 323b is provided at the center of the flexible portion 323a. The pressure plate 323b is made of resin materials such as polypropylene (PP) or polyphenylene sulfide (PPS). Furthermore, the pressure plate 323b can be integrally formed with the flexible portion 323a or formed separately from it. Moreover, the pressure plate 323b can be provided as needed; it can be fixed to the valve body 324 or omitted.

[0088] The valve body 324 has a shaft portion 324a, a flange portion 324b, and a sealing portion 324c. The shaft portion 324a and the flange portion 324b are made of resin materials such as polypropylene (PP) or polyphenylene sulfide (PPS), and are integrally formed by injection molding or the like.

[0089] The shaft portion 324a extends in either direction a1 or a2 and is inserted into the hole 321d. The width of the shaft portion 324a is smaller than the width of the hole 321d. Therefore, movement of the shaft portion 324a in either direction a1 or a2 is permitted, and a gap is formed between the outer peripheral surface of the shaft portion 324a and the inner peripheral surface of the hole 321d to allow ink flow. The end of the shaft portion 324a in the direction a1 is disposed in the downstream liquid chamber Q2 and contacts the pressure plate 323b. On the other hand, the end of the shaft portion 324a in the direction a2 is disposed in the upstream liquid chamber Q1.

[0090] A flange portion 324b is disposed at the end of the shaft portion 324a in the a2 direction and is positioned within the upstream liquid chamber Q1. The width of the flange portion 324b is greater than the width of the hole 321d, and less than the width of the upstream liquid chamber Q1 or the recess 321a. Because the width of the flange portion 324b is greater than the width of the hole 321d, the flange portion 324b allows the sealing portion 324c to be positioned between the flange portion 324b and the valve seat 321c. Furthermore, because the width of the flange portion 324b is less than the width of the recess 321a, movement of the flange portion 324b in the a1 or a2 direction is permitted, and a gap is formed between the outer peripheral surface of the flange portion 324b and the inner peripheral surface of the recess 321a to allow ink flow.

[0091] The sealing portion 324c is disposed on the surface of the flange portion 324b in such a way that it has a portion between the valve seat 321c and the flange portion 324b. The sealing portion 324c is an elastic component, for example, made of a rubber material or an elastomer material such as silicone or fluorine.

[0092] The force-applying component 325 is an elastic body disposed in the upstream liquid chamber Q1, which applies force to the valve body 324 toward the valve seat 321c. Figure 6 In the example shown, the force-applying component 325 is a helical spring, and it is positioned between the valve body 324 and the sealing component 322 in a compressed and deformed state. Additionally, although in Figure 6 In the example shown, the width of the helical spring is fixed, but it is not limited to this. For example, the width of the helical spring can be set to increase from one end to the other. In addition, the force-applying component 325 is not limited to a helical spring, as long as it can apply force to the valve body 324 toward the valve seat 321c. It can also be, for example, a leaf spring.

[0093] The force-applying component 326 is an elastomer disposed within the downstream side liquid chamber Q2, and is used to adjust the ease with which the flexible portion 323a undergoes flexural deformation. Figure 6 In the example shown, the force-applying component 326 is a helical spring and is positioned between the valve seat 321c and the pressure plate 323b. Additionally, although in Figure 6 In the example shown, the width of the helical spring is fixed, but not limited to this. For example, the width of the helical spring can also be set to increase from one end to the other. Furthermore, the force-applying component 326 is not limited to a helical spring, but can also be, for example, a leaf spring. Moreover, the force-applying component 326 can be provided as needed, or it can be omitted.

[0094] In the pressure regulating valve 320 described above, under normal conditions where the pressure of the ink in the downstream liquid chamber Q2 is maintained at a negative pressure within a predetermined range, the sealing part 324c is pressed tightly against the valve seat 321c by the force applied by the force-applying member 325, thereby cutting off the upstream liquid chamber Q1 and the downstream liquid chamber Q2. That is, under normal conditions, the flow channel Q is blocked.

[0095] On the other hand, when the negative pressure of the ink in the downstream liquid chamber Q2 rises above a predetermined level due to ink ejection by the liquid ejector head 310, such as Figure 6 As shown by the double-dotted line, with the flexural deformation of the flexible portion 323a, the pressure plate 323b displaces the valve body 324 against the applied forces of the force-applying components 325 and 326. As a result, a gap is formed between the sealing portion 324c and the valve seat 321c, thereby connecting the upstream liquid chamber Q1 and the downstream liquid chamber Q2 via the hole 321d. That is, the flow channel Q is opened.

[0096] When the flow channel Q is opened, ink from the liquid storage section 400 is supplied from the upstream liquid chamber Q1 to the downstream liquid chamber Q2 via the orifice 321d. With this supply, the negative pressure of the ink in the downstream liquid chamber Q2 decreases. As a result, the sealing part 324c and the valve seat 321c are pressed tightly together again by the force applied by the force-applying member 325, thereby cutting off the upstream liquid chamber Q1 and the downstream liquid chamber Q2. As described above, the pressure regulating valve 320 is opened and closed according to the pressure of the ink in the liquid nozzle 310, thereby maintaining the pressure of the ink in the downstream liquid chamber Q2 at a negative pressure within a predetermined range.

[0097] 1-4. Operation of the 3D printing apparatus

[0098] Figure 7 This diagram illustrates the change in the positional relationship between the liquid nozzle 310 and the pressure regulating valve 320. (See figure.) Figure 7 As shown, the direction c2, which is the direction from the pressure regulating valve 320 toward the liquid nozzle 310, can be varied. That is, the nozzle surface F of the liquid nozzle 310 can be not only parallel to the horizontal plane, but also inclined relative to the horizontal plane. Furthermore, in Figure 7 The example illustrates the case where the position of the liquid ejector head 310 is set to the center position of the liquid ejector head 310. Similarly, in Figure 7 The example illustrates the case where the position of the pressure regulating valve 320 is set to the center position of the pressure regulating valve 320.

[0099] exist Figure 7 The diagram shows several representative states A, B, C, D, and E of the liquid ejector unit 300 with different orientations. Additionally, although in Figure 7 In the process, the positions of the liquid ejector unit 300 in states A, B, C, D, and E are different from each other, but the following description remains the same even if the positions of the liquid ejector unit 300 in states A, B, C, D, and E are the same. Furthermore, although in Figure 7 The example illustrates a case where multiple nozzles N are arranged in a cross or inclined direction relative to the horizontal plane; however, this arrangement can also be parallel to the horizontal plane. When the arrangement is parallel to the horizontal plane, it has the advantage of minimizing the generation of pressure differences between the nozzles N.

[0100] exist Figure 7 In state A, as shown by the solid line, the c2 direction points downwards towards the Z2 direction, which is the vertical direction. Figure 7 In state B, indicated by the double-dotted line, the c2 direction faces a direction with an angle of 45° to the Z2 direction. Figure 7In state C, indicated by the double-dotted line, the c2 direction points towards the horizontal direction, which forms a 90° angle with the Z2 direction. Figure 7 In state D, indicated by the double-dotted line, the c2 direction faces a direction with an angle of 135° to the Z2 direction. Figure 7 In state E, indicated by the double-dotted line, the c2 direction is oriented towards the direction that forms an angle of 180° with the Z2 direction, which is the Z1 direction, i.e., the vertical direction, and is upward.

[0101] In both states A and B, the vertical position of the liquid nozzle 310 is lower than that of the pressure regulating valve 320. However, the distance L between the centers of the vertical liquid nozzle 310 and the pressure regulating valve 320 in state B is shorter than that in state A. Therefore, the ink pressure inside the liquid nozzle 310 in state B is lower than that in state A. That is, the negative pressure of the ink inside the liquid nozzle 310 in state B is greater than that in state A.

[0102] In state C, the vertical position of the liquid nozzle 310 is the same as that of the pressure regulating valve 320. Therefore, the ink pressure inside the liquid nozzle 310 in state C is lower than the ink pressure inside the liquid nozzle 310 in states A and B. That is, the negative pressure of the ink inside the liquid nozzle 310 in state C is greater than the negative pressure of the ink inside the liquid nozzle 310 in states A and B.

[0103] In states D and E, the vertical position of the liquid nozzle 310 is higher than that of the pressure regulating valve 320. Therefore, the ink pressure inside the liquid nozzle 310 in states D and E is lower than the ink pressure inside the liquid nozzle 310 in states A, B, and C. That is, the negative pressure of the ink inside the liquid nozzle 310 in states D and E is greater than the negative pressure of the ink inside the liquid nozzle 310 in states A, B, and C.

[0104] Furthermore, the distance L between the centers of the liquid nozzle 310 and the pressure regulating valve 320 in the vertical direction in state E is longer than the distance L between the centers of the liquid nozzle 310 and the pressure regulating valve 320 in the vertical direction in state D. Therefore, the ink pressure inside the liquid nozzle 310 in state E is lower than the ink pressure inside the liquid nozzle 310 in state D. That is, the negative pressure of the ink inside the liquid nozzle 310 in state E is greater than the negative pressure of the ink inside the liquid nozzle 310 in state D.

[0105] Here, from Figure 7As can be seen, in this embodiment, the variation of distance L in states A, B, C, D, and E is relatively small. Therefore, the deviation of the ejection characteristics in states A, B, C, D, and E is not significant.

[0106] Figure 13 This diagram illustrates the change in the positional relationship between the liquid nozzle 310 and the pressure regulating valve 320 in the comparative example. Additionally, Figure 13 The states A', B', C', D', and E' shown are respectively related to Figure 7 The states A, B, C, D, and E shown are the same.

[0107] exist Figure 13 In the comparative example shown, the pressure regulating valve 320 is mounted on the base 210. Therefore, from Figure 13 and Figure 7 The comparison shows that the changes in distance L' under states A', B', C', D', and E' are greater than the changes in distance L under states A, B, C, D, and E. Therefore, in the comparative example, the deviations in ejection characteristics under states A', B', C', D', and E' are larger.

[0108] As described above, the stereolithography printing apparatus 100 includes a base 210, an arm 220, a liquid ejector head 310, a liquid storage unit 400, a supply channel 500, and a pressure regulating valve 320. Here, as previously mentioned, the arm 220 is supported by the base 210 and has N (N≥1) joints 231 to 236, which are examples of movable parts, allowing the angle of the liquid ejector head 310 relative to a horizontal surface to change. The liquid ejector head 310 is fixed to the top of the arm 220 and ejects ink, an example of a liquid, to the workpiece W. The liquid storage unit 400 stores the ink. The supply channel 500 connects the liquid storage unit 400 and the liquid ejector head 310, and supplies ink from the liquid storage unit 400 to the liquid ejector head 310. The pressure regulating valve 320 is fixed on the arm 220 and positioned midway through the supply channel 500 to adjust the pressure of the ink supplied to the liquid nozzle 310. Here, K (1≤K≤N) joints 231 to joints 236 are provided between the pressure regulating valve 320 and the base 210.

[0109] In the above-described 3D printing apparatus 100, since the pressure regulating valve 320 is located midway through the supply channel 500, the pressure of the ink in the liquid nozzle 310 can be adjusted within a predetermined range by the pressure regulating valve 320, regardless of the vertical positional relationship between the liquid nozzle 310 and the liquid storage section 400. Therefore, compared to a structure that does not utilize the pressure regulating valve 320, pressure fluctuations in the ink within the liquid nozzle 310 caused by the actuation of the arm 220 can be reduced.

[0110] Furthermore, since the pressure regulating valve 320 is fixed to the arm 220, compared to a structure where the positional relationship between the pressure regulating valve 320 and the base 210 is fixed, the variation in the water level difference between the ink in the liquid nozzle 310 and the ink in the pressure regulating valve 320 can be reduced. Therefore, the pressure variation of the ink in the liquid nozzle 310 caused by the actuation of the arm 220 can also be reduced.

[0111] Through the above, in the stereolithography printing apparatus 100, the variation in ink ejection characteristics in the liquid ejection head 310 due to pressure fluctuations in the ink within the liquid ejection head 310 caused by the driving of the arm 220 can be appropriately reduced. Therefore, in the stereolithography printing apparatus 100 of this embodiment, compared to a structure without a pressure regulating valve 320, or a structure where the pressure regulating valve 320 is mounted on the base 210 as in the aforementioned comparative example, stable ink ejection by the liquid ejection head 310 can be achieved, thereby realizing higher quality printing.

[0112] In this embodiment, the number N of joints 231 to 236 is 6. Here, 6 of the 6 joints 231 to 236 are arranged between the pressure regulating valve 320 and the base 210 along the arm 220. Thus, with K (K≥(N / 2)) joints, compared to a structure with fewer than K joints (N / 2), it has the advantage of easily reducing fluctuations in the water level difference between the ink in the liquid nozzle 310 and the ink in the pressure regulating valve.

[0113] In particular, in this embodiment, since the liquid nozzle 310 is fixed to the tip of the arm 220 and K=N, the positional relationship between the liquid nozzle 310 and the pressure regulating valve 320 can be fixed regardless of the posture of the arm 220. Furthermore, in multi-axis robots such as the 6-axis robot 200, the arm 220 can take various shapes even if the position and posture of the end effector are the same. Therefore, even when K<N, by selecting the posture from among the multiple postures where the positional relationship between the liquid nozzle 310 and the pressure regulating valve 320 changes less, the variation in the water level difference between the ink in the liquid nozzle 310 and the ink in the pressure regulating valve 320 can be reduced. However, when K=N, it has the advantage that the positional relationship between the liquid nozzle 310 and the pressure regulating valve 320 is fixed regardless of whether the multiple postures can be taken.

[0114] Furthermore, as previously described, the supply channel 500 has an upstream channel 510 and a downstream channel 520, the upstream channel 510 connecting the liquid storage section 400 and the pressure regulating valve 320, and the downstream channel 520 connecting the pressure regulating valve 320 and the liquid nozzle 310. The pressure regulating valve 320 includes: an upstream liquid chamber Q1 connected to the upstream channel 510; a downstream liquid chamber Q2 connected to the downstream channel 520; a valve body 324 for opening and closing between the upstream liquid chamber Q1 and the downstream liquid chamber Q2; a flexible portion 323a that is flexible and forms part of the inner wall of the downstream liquid chamber Q2; and force-applying members 325 and 326 that apply force to the flexible portion 323a in a direction that expands the volume of the downstream liquid chamber Q2. The pressure regulating valve 320 opens and closes according to the negative pressure of the downstream liquid chamber Q2, thereby maintaining the pressure of the ink supplied to the liquid nozzle 310 at a predetermined negative pressure state.

[0115] Here, the length of the downstream flow channel 520 is shorter than the length of the upstream flow channel 510. Therefore, compared to a structure where the length of the downstream flow channel 520 is longer than the length of the upstream flow channel 510, the adjustment accuracy of the ink pressure within the liquid nozzle 310 implemented by the pressure regulating valve 320 can be easily improved. Furthermore, by setting the length of the upstream flow channel 510 to be longer than the length of the downstream flow channel 520, compared to a structure where the length of the upstream flow channel 510 is shorter than the length of the downstream flow channel 520, the freedom of positioning the liquid storage section 400 can be increased. Additionally, the length of the downstream flow channel 520 is the length of the supply flow channel 500 between the pressure regulating valve 320 and the liquid nozzle 310. The length of the upstream flow channel 510 is the length of the supply flow channel 500 between the pressure regulating valve 320 and the liquid storage section 400.

[0116] Furthermore, as mentioned above, the liquid reservoir 400 is positioned at a higher position in the vertical direction compared to the moving area of ​​the liquid nozzle 310. Therefore, the pressure of the ink applied from the liquid reservoir 400 to the pressure regulating valve 320 is higher than the pressure of the ink in the liquid nozzle 310. Thus, the pressure difference between them allows ink to be supplied from the liquid reservoir 400 to the liquid nozzle 310 via the pressure regulating valve 320.

[0117] Furthermore, as previously described, arm 220 includes arms 221 to 226. Here, arm 226, which fixes the liquid ejector head 310, is an example of a first arm. Furthermore, arm 225, which supports arm 226 in a manner capable of rotating around a sixth rotation axis O6, is an example of a second arm. As previously described, the liquid ejector head 310 has a nozzle surface F provided with a nozzle N for ejecting ink, and when viewed along the direction of the sixth rotation axis O6, the sixth rotation axis O6 overlaps with the nozzle surface F. Therefore, compared to a structure where the sixth rotation axis O6 and the nozzle surface F do not overlap when viewed in the same direction, even if the liquid ejector head 310 rotates around the sixth rotation axis, the influence of its torque on the ejection characteristics of the liquid ejector head 310 can be reduced.

[0118] Furthermore, as previously described, the liquid ejector head 310 has a first nozzle array L1 and a second nozzle array L2, which are examples of nozzle arrays arranged as a plurality of nozzles N for ejecting ink. Here, as... Figure 3 As shown, at least a portion of the pressure regulating valve 320 is positioned between nozzles N1 and N2 at both ends of the arrangement direction of the plurality of nozzles N. Therefore, when the arrangement direction of the plurality of nozzles N is along a vertical direction, the pressure difference between the ink in the nozzles N and the ink in the pressure regulating valve 320 can be minimized.

[0119] Furthermore, the flexible portion 323a has a shape that extends in a direction that does not intersect with the arrangement direction of the plurality of nozzles N. Therefore, compared with a structure in which the flexible portion 323a extends in a direction that intersects with the arrangement direction, it is possible to miniaturize or thin the liquid ejector unit 300. For example, for narrow areas such as workpieces with concave shapes, printing can be performed without the liquid ejector unit 300 contacting the workpiece.

[0120] 2. Second Implementation Method

[0121] The second embodiment of the present invention will now be described. Elements that function and operate the same as those in the first embodiment as illustrated below will be referred to by the same reference numerals used in the description of the first embodiment, and detailed descriptions of each will be omitted as appropriate.

[0122] In the aforementioned Figure 7 In the example shown, the negative pressure of the ink within the liquid ejector head 310, from the lower side to the higher side, is in the order of state A, state B, state C, state D, and state E. Therefore, the ease of ink ejection from the liquid ejector head 310, from the easy ejection side to the difficult ejection side, is in the order of state A, state B, state C, state D, and state E. Therefore, in this embodiment, different drive signals Com are used in states A, B, C, D, and E.

[0123] Figure 8 This diagram illustrates an example of multiple drive signals Com-A to Com-E, each comprising different drive pulses. Figure 8 The example illustrates a scenario where the amplification rate of the amplifier circuit in the aforementioned drive signal generation circuit 640 is changed, thereby allowing the drive signal generation circuit 640 to switch and generate multiple drive signals Com-A to Com-E with different amplitudes. Furthermore, the waveforms of drive signals Com-A to Com-E are merely an example and are not limited to this.

[0124] In specific terms, the drive signal Com-A is the signal generated by the drive signal generation circuit 640 as the drive signal Com in the aforementioned state A. The drive signal Com-A includes a drive pulse PD1 that drops from the reference potential V0 to potential VL1 and then rises to a potential VH1 that is higher than the reference potential V0. Here, the difference between potential VL1 and potential VH1 is the amplitude A1 of the drive pulse PD1.

[0125] The drive signal Com-B is a signal generated by the drive signal generation circuit 640 as the drive signal Com under the aforementioned state B. The drive signal Com-B includes a drive pulse PD2 that drops from the reference potential V0 to potential VL2 and then rises to a potential VH2, which is higher than the reference potential V0. Here, the difference between potential VL2 and potential VH2 is the amplitude A2 of the drive pulse PD2. The amplitude A2 is greater than the aforementioned amplitude A1.

[0126] The drive signal Com-C is a signal generated by the drive signal generation circuit 640 as the drive signal Com under the aforementioned state C. The drive signal Com-C includes a drive pulse PD3 that drops from the reference potential V0 to potential VL3 and then rises to a potential VH3, which is higher than the reference potential V0. Here, the difference between potential VL3 and potential VH3 is the amplitude A3 of the drive pulse PD3. The amplitude A3 is greater than the aforementioned amplitude A2.

[0127] The drive signal Com-D is a signal generated by the drive signal generation circuit 640 as the drive signal Com in the aforementioned state D. The drive signal Com-D includes a drive pulse PD4 that drops from the reference potential V0 to potential VL4 and then rises to a potential VH4, which is higher than the reference potential V0. Here, the difference between potential VL4 and potential VH4 is the amplitude A4 of the drive pulse PD4. The amplitude A4 is greater than the aforementioned amplitude A3.

[0128] The drive signal Com-E is a signal generated by the drive signal generation circuit 640 as the drive signal Com in the aforementioned state E. The drive signal Com-E includes a drive pulse PD5 that drops from the reference potential V0 to potential VL5 and then rises to a potential VH5, which is higher than the reference potential V0. Here, the difference between potential VL5 and potential VH5 is the amplitude A5 of the drive pulse PD5. The amplitude A5 is greater than the aforementioned amplitude A4.

[0129] Figure 9 This is a flowchart illustrating the operation of the three-dimensional printing apparatus 100 according to the second embodiment. (For example...) Figure 9 As shown, in the stereoscopic printing apparatus 100, firstly, in step S100, it is determined whether there is a printing instruction. This determination is performed, for example, by checking whether the information acquisition unit 611 has acquired printing data Img.

[0130] Until a printing instruction is received, step S100 is repeated. If a printing instruction is received, a printing path is determined in step S110. This determination is made, for example, by the arm control unit 612 determining the printing path as the movement path of the liquid ejector head 310. At this time, the posture of the liquid ejector head 310 in the printing path is also determined by the arm control unit 612. Furthermore, the printing path is not set such that all the nozzles N at the start of printing are positioned higher in the vertical direction than the pressure regulating valve 320, but rather that the lowermost nozzle N in the vertical direction is positioned lower in the vertical direction than the pressure regulating valve 320. Therefore, the occurrence of excessively high negative pressure of the ink in the liquid ejector head 310 at the start of printing can be reduced. Additionally, the start of printing refers to the timing when at least a portion of the nozzle surface F of the liquid ejector head 310 is facing the workpiece and begins to eject droplets from the nozzle N.

[0131] Then, in step S120, printing begins. That is, in step S120, based on the information from the information acquisition unit 611, drive control of the arm 220 implemented by the arm control unit 612 and drive control of the liquid ejection head 310 implemented by the ejection control unit 613 are performed.

[0132] Next, in step S130, position and posture information related to the position and posture of the liquid nozzle 310 is obtained. This is obtained, for example, by the information acquisition unit 611 acquiring information D1 from the arm drive mechanism 230 as the position and posture information.

[0133] Next, in step S140, it is determined whether the aforementioned distance L has changed. This determination is performed, for example, by the information acquisition unit 611 calculating the distance L based on the information D1 from the arm drive mechanism 230.

[0134] If the distance L remains unchanged, steps S130 and S140 are repeated. However, if the distance L changes, the drive pulse is adjusted in step S150. This adjustment is performed, for example, by the ejection control unit 613 changing the amplification rate of the amplification circuit in the drive signal generation circuit 640 based on information D1 from the arm drive mechanism 230. Here, as described above, the amplification rate is changed continuously or in stages, generating drive signals Com-A to Com-E according to states A, B, C, D, and E.

[0135] Then, in step S160, it is determined whether there is an indication that printing has ended. If there is no indication that printing has ended, steps S130 to S160 are repeated. On the other hand, if there is an indication that printing has ended, the process ends.

[0136] In this embodiment, at least a portion of the valve body 324 is positioned at a higher position in the vertical direction than the lowermost nozzle N among the plurality of nozzles N in the liquid ejector head 310 at the start of printing. This position or orientation of the liquid ejector head 310 at the start of printing provides the advantage of a stable supply of ink to the liquid ejector head 310 not only at the start of printing but also subsequently.

[0137] Furthermore, as described above, the stereolithography printing apparatus 100 includes an information acquisition unit 611 and an ejection control unit 613. The information acquisition unit 611 acquires information D1 related to the position and posture of the liquid ejection head 310, and the ejection control unit 613 controls the drive of the liquid ejection head 310 based on the information D1. Therefore, even if the pressure of the ink in the liquid ejection head 310 changes due to the change in the vertical positional relationship between the liquid ejection head 310 and the pressure regulating valve 320, the drive of the liquid ejection head 310 can be controlled in a way that cancels it out.

[0138] Furthermore, as previously described, the ejection control unit 613 switches between using drive pulses PD1 to PD5 to drive the liquid ejector head 310 based on information D1. Here, one of the drive pulses PD1 to PD5 is an example of a first drive pulse used for a first state. The other drive pulse is an example of a second drive pulse used for a second state. As described above, the system switches between a first state where the liquid ejector head 310 is in a first position and a second state where the liquid ejector head 310 is in a second position different from the first position and uses a second drive pulse with a different waveform than the first drive pulse. By switching the drive pulses in this way, even if the pressure of the ink inside the liquid ejector head 310 changes due to changes in the vertical positional relationship between the liquid ejector head 310 and the pressure regulating valve 320, the drive of the liquid ejector head 310 can be controlled in a way that cancels out these changes.

[0139] Although this embodiment shows an example of setting the printing path so that the lowermost nozzle N in the vertical direction among the plurality of nozzles N is located further down in the vertical direction than the pressure regulating valve 320, and generating a drive signal based on the posture of the liquid ejector head 310 such as state A, state B, state C, state D, and state E, these controls do not necessarily need to be performed on both sides, and can also be performed individually as appropriate depending on the shape of the workpiece W or the printing pattern.

[0140] 3. Third Implementation Method

[0141] The third embodiment of the present invention will now be described. Elements that function and operate the same as those in the first embodiment in the following examples will be referred to by the same reference numerals used in the description of the first embodiment, and detailed descriptions of each will be omitted as appropriate.

[0142] Figure 10 This diagram illustrates the pressure distribution of ink within the first nozzle array L1 or the second nozzle array L2. Figure 10 The diagram shows the relationship between the position of the nozzles N in the Z1 direction and the negative pressure of the ink within the nozzles N when the arrangement directions of the multiple nozzles N are orthogonal to the horizontal plane. Furthermore, the following explanation also shows the same tendency when the arrangement directions of the multiple nozzles N are inclined and intersecting relative to the horizontal plane.

[0143] like Figure 10 As shown on the right, when the arrangement directions of multiple nozzles N intersect with respect to the horizontal plane, such as Figure 10As shown on the left, differences in negative pressure of the ink exist between the nozzles N. This is because the nozzles N are connected by spaces Ra, etc., provided inside the liquid ejector head 310, and gravity causes the ink to move in the opposite direction to Z1. Here, the nozzle N located at the top of the vertical direction, i.e., in the Z1 direction, has the greatest negative pressure of the ink. The negative pressure of the ink in the other nozzles N increases as it gets closer to the nozzle N located at the top of the Z1 direction.

[0144] Therefore, in this embodiment, the first nozzle array L1 and the second nozzle array L2 are divided into four nozzle sections GN1, GN2, GN3, and GN4, using different drive signals Com in each nozzle section. That is, the drive pulse is adjusted for each nozzle section based on the orientation of the liquid ejector head 310 around the c-axis. In this embodiment, for example, the drive circuit 340 has multiple amplifiers for each nozzle section to adjust the amplitude of the drive pulse. Furthermore, the number of divisions is not limited to... Figure 10 The examples shown are arbitrary.

[0145] Figure 11 This is a flowchart illustrating the operation of the stereolithography printing apparatus according to the third embodiment. In this embodiment, similar to the first embodiment described above, steps S100 to S150 are executed, and then, in step S170, it is determined whether the posture of the liquid ejector head 310 around the c-axis has changed. This determination is performed, for example, by the information acquisition unit 611 based on information D1 from the arm drive mechanism 230.

[0146] If the posture remains unchanged, repeat steps S130 to S170. On the other hand, if the posture changes, in step S180, the drive pulse is adjusted for each nozzle. Then, step S160 is performed in the same manner as in the first embodiment described above.

[0147] As described above, in this embodiment, the first nozzle array L1 or the second nozzle array L2 is divided into multiple nozzle sections GN1, GN2, GN3, and GN4. The ejection control unit 613 of this embodiment adjusts the waveform of the drive pulse for driving the liquid ejection head 310 for each nozzle section based on information D1. As described above, the drive pulse for driving the liquid ejection head 310 is different for each nozzle section. Therefore, even if a pressure difference in ink occurs between the nozzle sections, the drive of the liquid ejection head 310 can be controlled to cancel it out.

[0148] 4. Fourth Implementation Method

[0149] The fourth embodiment of the present invention will now be described. Elements that function and operate the same as those in the first embodiment in the following examples will be referred to by the same symbols used in the description of the first embodiment, and detailed descriptions of each will be omitted as appropriate.

[0150] Figure 12 This is a schematic diagram illustrating the three-dimensional printing apparatus according to the fourth embodiment. (See attached diagram.) Figure 12 As shown, the stereolithography printing apparatus of this embodiment is the same as the stereolithography printing apparatus 100 of the first embodiment, except that it has a liquid storage unit 400A, a supply channel 500A, and a pressurizing mechanism 800 instead of a liquid storage unit 400 and a supply channel 500. The liquid storage unit 400A is the same as the liquid storage unit 400 except that its position is different.

[0151] The supply channel 500A supplies ink from the liquid storage section 400A to the liquid nozzle 310. The supply channel 500A is divided into an upstream channel 510A and a downstream channel 520 by a pressure regulating valve 320. The upstream channel 510A is disposed inside the arm 220. By distributing at least a portion of the supply channel 500A inside the arm 220, the possibility of the supply channel 500A contacting the workpiece W during the movement of the arm 220 can be reduced. Furthermore, the upstream channel 510A is appropriately constructed using a bendable or rotatable connector, for example, in addition to having a flexible tube body.

[0152] The pressurizing mechanism 800 is a pump that pressurizes the ink supplied from the liquid storage section 400A to the pressure regulating valve 320. Figure 12 In the example shown, a pressurizing mechanism 800 is provided midway through the upstream flow channel 510A. By utilizing this pressurizing mechanism 800, regardless of the location of the liquid storage section 400A, the pressure of the ink applied from the liquid storage section 400A to the pressure regulating valve 320 can be higher than the pressure of the ink in the liquid nozzle 310. Therefore, these pressure differences can be used to supply ink from the liquid storage section 400A to the liquid nozzle 310 via the pressure regulating valve 320.

[0153] 5. Variations

[0154] The methods illustrated above can be modified in various ways. Specific modifications applicable to the aforementioned methods are illustrated below. Furthermore, two or more methods chosen arbitrarily from the examples below can be appropriately combined without contradicting each other.

[0155] 5-1. Variation Example 1

[0156] Although the foregoing example illustrates a structure in which the pressure regulating valve is fixed to the topmost arm among the multiple arms constituting the robotic arm, it is not limited to this structure, and the pressure regulating valve may also be fixed to other arms.

[0157] 5-2. Variation Example 2

[0158] While the foregoing description illustrates a structure using a 6-axis vertical multi-axis robot, it is not limited to that structure. The mechanism for changing the position and orientation of the liquid nozzle can be any arm with three or more movable parts; for example, it can be a vertical multi-axis robot other than 6 axes, or a horizontal multi-axis robot. Furthermore, the movable parts are not limited to rotational mechanisms; they can also be, for example, telescopic mechanisms.

[0159] 5-3. Variation Example 3

[0160] Although the foregoing embodiments illustrate a structure for printing using one type of ink, the invention is not limited to this structure and can also be applied to structures for printing using two or more types of ink.

[0161] 5-4. Variation Example 4

[0162] The application of the stereolithography printing apparatus of the present invention is not limited to printing. For example, the stereolithography printing apparatus that ejects a solution of color material can be used as a manufacturing apparatus for color filters in liquid crystal display devices. Furthermore, the stereolithography printing apparatus that ejects a solution of conductive material can be used as a manufacturing apparatus for wiring and electrodes in wiring substrates.

[0163] Symbol Explanation

[0164] 100…3D printing apparatus; 200…robot; 210…base; 220…arm; 221…arm; 222…arm; 223…arm; 224…arm; 225…arm; 226…arm; 230…arm drive mechanism; 231…joint; 232…joint; 233…joint; 234…joint; 235…joint; 236…joint; 300…liquid nozzle unit; 310…liquid nozzle; 311…piezoelectric element; 312…flow channel substrate; 312a…supply flow channel; 312b…connecting flow channel; 312c…supply liquid chamber; 313…pressure chamber substrate; 314…nozzle plate; 315…vibration absorber; 316…vibrating plate; 317…wiring substrate; 318…frame section; 3 18a…Inlet; 320…Pressure regulating valve; 321…Flow channel component; 321a…Recess; 321b…Recess; 321c…Valve seat; 321d…Hole; 322…Sealing component; 322a…Part; 323…Sealing component; 323a…Flexible part; 323b…Pressure plate; 324…Valve body; 324a…Shaft; 324b…Flange; 324c…Sealing part; 325…Force application component; 326…Force application component; 330…Displacement sensor; 340…Drive circuit; 350…Support; 400…Liquid storage section; 400A…Liquid storage section; 500…Supply channel; 500A…Supply channel; 510…Upstream channel; 510A…Upstream channel; 520…Downstream channel; 52 1…flow channel component; 600…control device; 610…processing circuit; 611…information acquisition unit; 612…arm control unit; 613…ejection control unit; 620…storage circuit; 630…power supply circuit; 640…drive signal generation circuit; 700…external device; 800…pressurization mechanism; A…state; A1…amplitude; A2…amplitude; A3…amplitude; A4…amplitude; A5…amplitude; B…state; C…state; Com…drive signal; Com-A…drive signal; Com-B…drive signal; Com-C…drive signal; Com-D…drive signal; Com-E…drive signal; Cv…pressure chamber; D…state; D1…information; D2…information; E…state; F…nozzle face; GN 1… Nozzle section; GN2… Nozzle section; GN3… Nozzle section; Img… Printing data; L… Distance; L1… First nozzle row; L2… Second nozzle row; N… Nozzle; N1… Nozzle; O1… First rotating shaft; O2… Second rotating shaft; O3… Third rotating shaft; O4… Fourth rotating shaft; O5… Fifth rotating shaft; O6… Sixth rotating shaft; P… Program; P1… Supply port; P2… Discharge port; PD… Drive pulse; PD1… Drive pulse; PD2… Drive pulse; PD3… Drive pulse; PD4… Drive pulse; PD5… Drive pulse; Q… Flow channel; Q1… Upstream side liquid chamber; Q2… Downstream side liquid chamber; R… Liquid storage chamber; Ra… Space; Rb… Space; S100… Step; S110… Step;S120…step; S130…step; S140…step; S150…step; S160…step; S170…step; S180…step; SI…control signal; Sk…control signal; T…bump; V0…reference potential; VBS…offset potential; VH1…potential; VH2…potential; VH3…potential; VH4…potential; VH5…potential; VHV…power supply potential; VL1…potential; VL2…potential; VL3…potential; VL4…potential; VL5…potential; W…workpiece; WF1…face; WF2…face; dCom…waveform specification signal.

Claims

1. A three-dimensional printing apparatus, characterized in that, have: Base; The arm is supported by the base; A liquid nozzle, which is fixed to the top of the arm, sprays liquid onto the workpiece; The liquid storage section stores liquids. A supply channel connects the liquid storage section and the liquid nozzle, and supplies liquid from the liquid storage section to the liquid nozzle; A pressure regulating valve, located midway through the supply channel, adjusts the pressure of the liquid supplied to the liquid nozzle. The arm has N movable parts, which allow the angle of the liquid nozzle relative to the horizontal plane to change, where N ≥ 1. The pressure regulating valve is fixed to the arm. K movable parts are provided between the pressure regulating valve and the base, wherein (N / 2)≤K≤N.

2. The three-dimensional printing apparatus as described in claim 1, characterized in that, K=N.

3. The three-dimensional printing apparatus as described in claim 1 or 2, characterized in that, The length of the supply channel between the pressure regulating valve and the liquid nozzle is shorter than the length of the supply channel between the pressure regulating valve and the liquid storage section.

4. The three-dimensional printing apparatus as described in claim 1, characterized in that, The supply channel has: An upstream flow channel that connects the liquid storage section and the pressure regulating valve; The downstream flow channel connects the pressure regulating valve and the liquid nozzle. The pressure regulating valve has: An upstream liquid chamber, which is connected to the upstream flow channel; A downstream liquid chamber, which is connected to the downstream flow channel; The valve body opens and closes between the upstream liquid chamber and the downstream liquid chamber; The flexible portion is flexible and forms part of the inner wall of the downstream side liquid chamber; A force-applying component applies force to the flexible portion in a direction that expands the volume of the downstream liquid chamber.

5. The three-dimensional printing apparatus as described in claim 4, characterized in that, The pressure regulating valve opens and closes according to the negative pressure of the downstream liquid chamber, thereby maintaining the pressure of the liquid supplied to the liquid nozzle at a predetermined negative pressure state.

6. The three-dimensional printing apparatus as described in claim 1, characterized in that, The pressure of the liquid applied from the liquid storage section to the pressure regulating valve is higher than the pressure of the liquid in the liquid nozzle.

7. The three-dimensional printing apparatus as described in claim 6, characterized in that, The liquid storage section is positioned at a higher position in the vertical direction compared to the moving area of ​​the liquid nozzle.

8. The three-dimensional printing apparatus as described in claim 6 or 7, characterized in that, It also has a pressurizing mechanism that pressurizes the liquid supplied from the liquid storage section to the pressure regulating valve.

9. The three-dimensional printing apparatus as claimed in claim 1, characterized in that, At least a portion of the supply channel is disposed inside the arm.

10. The three-dimensional printing apparatus as claimed in claim 1, characterized in that, The arm has: The first arm secures the liquid ejector head; The second arm supports the first arm in a manner that allows it to rotate about a rotation axis. The liquid ejector head has a nozzle surface, on which a nozzle is provided for ejecting liquid. The rotation axis overlaps with the nozzle surface when viewed along the direction of the rotation axis.

11. The three-dimensional printing apparatus as claimed in claim 1, characterized in that, The liquid ejector head has a nozzle array consisting of multiple nozzles arranged to eject liquid. The position of at least a portion of the pressure regulating valve in the arrangement direction of the plurality of nozzles is the position between the two ends of the nozzles in the arrangement direction of the plurality of nozzles.

12. The three-dimensional printing apparatus as described in claim 4 or 5, characterized in that, The liquid ejector head has a nozzle array consisting of multiple nozzles arranged to eject liquid. The flexible portion has a shape that extends in a direction that does not intersect with the arrangement direction of the plurality of nozzles.

13. The three-dimensional printing apparatus as described in claim 4 or 5, characterized in that, The liquid ejector head has a nozzle array consisting of multiple nozzles arranged to eject liquid. At the start of printing, at least a portion of the valve body is positioned at a higher position in the vertical direction than the lowermost nozzle among the plurality of nozzles.

14. The three-dimensional printing apparatus as claimed in claim 1, characterized in that, Switching between the first and second states. The first state is when the liquid nozzle is in a first posture, and the liquid nozzle is driven by a first driving pulse. The second state is a state in which the liquid nozzle is driven by a second driving pulse that is different from the first driving pulse waveform when the liquid nozzle is in a second posture that is different from the first posture.

15. The three-dimensional printing apparatus as described in claim 14, characterized in that, The liquid ejector head has a nozzle array consisting of multiple nozzles arranged to eject liquid. The nozzle array is divided into multiple nozzle sections. The drive pulses used to drive the liquid ejection head are different for each of the nozzle sections.

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