Imaging device

Abstract

In the present invention, a first timing at which a first event occurred is determined on the basis of first imaging data (D1) output from an event-based camera (61). A second event that occurs after a predetermined time period is imaged by a high-speed camera (62) on the basis of the first timing. Thus, the second event can be imaged at an appropriate timing using the high-speed camera (62), which can capture images for short time periods.

Description

Imaging device

[0001] The present invention relates to an imaging device using a high-speed camera.

[0002] In precision and micromachining equipment, such as semiconductor manufacturing equipment, even slight variations in operation can lead to a decline in process quality. For this reason, detailed observation of equipment operation is often required for design verification and troubleshooting. However, it is difficult to capture detailed images of high-speed rotational movements of objects or high-speed flows of liquids using standard video cameras. Therefore, high-speed cameras have traditionally been used to observe high-speed equipment operation.

[0003] A conventional technique for observing high-speed operation of a device using a high-speed camera is described in, for example, Patent Document 1.

[0004] Japanese Patent Application Laid-Open No. 2021-167838

[0005] A typical video camera has a frame rate, which indicates the number of frame images per unit time, of around 30 to 60 frames per second, whereas a high-speed camera can shoot at a frame rate of several thousand frames per second or more.

[0006] However, with high-speed cameras, the captured data cannot be transferred to a computer in time while the camera is capturing the image, so the captured data is stored in the camera's built-in memory. Therefore, the available capture time of a high-speed camera is limited depending on the memory capacity. For example, the available capture time may be limited to tens of microseconds or less. This creates the problem of difficulty in capturing images with a high-speed camera in a timely manner when an event to be observed occurs in the device.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an imaging device that can capture an image of an observation target phenomenon at an appropriate timing using a high-speed camera that has a short imaging time.

[0008] In order to solve the above problem, a first invention of the present application is an imaging device comprising an event-based camera, a high-speed camera, and a timing determination unit that determines a first timing at which a first event occurs based on first imaging data output from the event-based camera, and based on the first timing, captures an image of a second event that occurs a predetermined time after the first event using the high-speed camera.

[0009] A second invention of the present application is the imaging device of the first invention, wherein the timing determination unit determines, as the first timing, the timing at which the number of pixels whose luminance values ​​have changed in the first shooting data becomes equal to or greater than a predetermined threshold value.

[0010] A third aspect of the present invention is the imaging device of the first aspect, wherein the timing determination section determines, as the first timing, a timing at which a specific pattern appears in the first photographic data.

[0011] A fourth invention of the present application is an imaging device according to any one of the first to third inventions, further comprising a trigger signal output unit that outputs a trigger signal to the high-speed camera based on the first timing determined by the timing determination unit.

[0012] A fifth aspect of the present invention is the imaging device of the fourth aspect, wherein the timing determination section and the trigger signal output section are configured by an FPGA or a microcomputer.

[0013] A sixth invention of the present application is an imaging device according to any one of the first to fifth inventions, which is used to observe the state of liquid being ejected from a nozzle onto an object, wherein the event-based camera photographs the liquid being ejected from the nozzle near the tip of the nozzle, the timing determination unit determines the time when the ejection of liquid from the nozzle begins as the first timing based on the first imaging data, and the high-speed camera photographs the liquid reaching the object a predetermined time after the first timing.

[0014] A seventh invention of the present application is an imaging device according to any one of the first to third inventions, which is used to observe the state of a liquid spreading on the surface of a substrate, wherein the event-based camera photographs a midpoint between the center and the outer edge of the substrate, the timing determination unit determines the time at which the liquid reaches the midpoint as the first timing based on the first imaging data, and the high-speed camera photographs the liquid reaching the outer edge of the substrate a predetermined time after the first timing.

[0015] According to the first to seventh aspects of the present invention, a first timing at which a first event occurs is determined based on first imaging data output from an event-based camera. Then, based on the first timing, a second event that occurs a predetermined time later is imaged by a high-speed camera. This allows the second event to be imaged at an appropriate timing using a high-speed camera with a short imaging time.

[0016] In particular, according to the second aspect of the present invention, it is possible to suppress erroneous detection of the first event.

[0017] In particular, according to the third aspect of the present invention, it is possible to suppress erroneous detection of the first event.

[0018] In particular, according to the fifth aspect of the present invention, after the first photographic data is acquired, a trigger signal can be quickly output to the high-speed camera.

[0019] In particular, according to the sixth aspect of the present invention, the first timing at which the ejection of liquid from the nozzle is started can be determined based on the first photographing data, and the liquid reaching the object can be photographed with a high-speed camera a predetermined time after the first timing.

[0020] In particular, according to the seventh aspect of the present invention, the first timing at which the liquid reaches the middle of the substrate can be determined based on the first photographing data, and then, a predetermined time after the first timing, the liquid reaching the outer edge of the substrate can be photographed with a high-speed camera.

[0021] FIG. 1 is a longitudinal sectional view of a substrate processing apparatus; FIG. 2 is a schematic view of a liquid supply unit connected to a nozzle head; FIG. 3 is a control block diagram of the substrate processing apparatus; FIG. 4 is a block diagram showing the functions of an imaging device; FIG. 5 is a block diagram showing the functions of the imaging device; FIG. 6 is a flowchart showing the flow of a photographing operation by the imaging device; FIG. 7 is a block diagram showing the functions of an imaging device according to a first modified example; FIG. 8 is a block diagram showing the functions of an imaging device according to a second modified example.

[0022] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0023] 1 is a longitudinal sectional view of a substrate processing apparatus 1 equipped with an imaging device 60 according to one embodiment of the present invention. The substrate processing apparatus 1 is an apparatus for supplying a processing liquid to the surface of a disk-shaped substrate W (silicon wafer) in a semiconductor wafer manufacturing process to clean the surface of the substrate W. As shown in FIG. 1, the substrate processing apparatus 1 includes a chamber 10, a substrate holding unit 20, a rotation mechanism 30, a processing liquid supply unit 40, a cup 50, an imaging device 60, and a control unit 70.

[0024] The chamber 10 is a housing that forms a processing space 11 for processing a substrate W. The chamber 10 has a sidewall 12 that surrounds the sides of the processing space 11, a top plate 13 that covers an upper portion of the processing space 11, and a bottom plate 14 that covers a lower portion of the processing space 11. A substrate holder 20, a rotation mechanism 30, a processing liquid supply unit 40, and a cup 50 are housed inside the chamber 10.

[0025] A loading / unloading port for loading / unloading a substrate W into / from the chamber 10 and a shutter for opening / closing the loading / unloading port are provided in a portion of the side wall 12 (not shown). The chamber 10 also has a window 15 in a portion of the side wall 12. The window 15 is made of a transparent resin such as polyvinyl chloride or glass. The boundary between the side wall 12 and the window 15 is sealed without any gaps.

[0026] The substrate holding unit 20 is a mechanism for holding the substrate W in a horizontal position inside the chamber 10. The substrate holding unit 20 holds the substrate W in a position in which the normal of the substrate W faces the vertical direction. As shown in FIG. 1 , the substrate holding unit 20 includes a disk-shaped spin base 21 and a plurality of chuck pins 22. The plurality of chuck pins 22 are provided at equal angular intervals on the outer periphery of the upper surface of the spin base 21. The substrate W is held by the plurality of chuck pins 22 with the processing surface on which a pattern is to be formed facing upward. Each chuck pin 22 contacts the lower surface of the peripheral edge of the substrate W and the outer peripheral edge surface of the substrate W. Each chuck pin 22 supports the substrate W at a position above the upper surface of the spin base 21 with a small gap therebetween.

[0027] A chuck pin switching mechanism 23 is provided inside the spin base 21 for switching the positions of the plurality of chuck pins 22. The chuck pin switching mechanism 23 switches the plurality of chuck pins 22 between a holding position where the chuck pins 22 hold the substrate W and a release position where the chuck pins 22 release the substrate W from the holding position.

[0028] The rotation mechanism 30 is a mechanism for rotating the substrate holding part 20. The rotation mechanism 30 is housed inside a motor cover 31 provided below the spin base 21. As indicated by the dashed line in FIG. 1 , the rotation mechanism 30 has a motor 32 and a support shaft 33. The support shaft 33 extends vertically. The lower end of the support shaft 33 is connected to the motor 32. The upper end of the support shaft 33 is fixed to the center of the lower surface of the spin base 21. When the motor 32 is driven, the support shaft 33 rotates around an axis 330 of the support shaft 33. Then, together with the support shaft 33, the substrate holding part 20 and the substrate W held by the substrate holding part 20 also rotate around the axis 330.

[0029] The processing liquid supply unit 40 is a mechanism that supplies a processing liquid to the upper surface of the substrate W held by the substrate holding unit 20. The processing liquid supply unit 40 has a nozzle 41. As shown in FIG. 1 , the nozzle 41 has a nozzle arm 411 and a nozzle head 412 provided at the tip of the nozzle arm 411. The nozzle arm 411 rotates in the horizontal direction by driving a motor (not shown). This allows the nozzle head 412 to move between a processing position (position in FIG. 1 ) above the substrate W held by the substrate holding unit 20 and a retracted position outside the cup 50.

[0030] 2 is a diagram schematically showing a liquid supply unit connected to the nozzle head 412. The nozzle head 412 is connected to a liquid supply source 414 that stores a processing liquid via a pipe 415. A pump 416 and a valve 417 are provided on the path of the pipe 415. When the valve 417 is opened and the pump 416 is operated with the nozzle head 412 placed at the processing position, the processing liquid is supplied from the liquid supply source 414 through the pipe 415 to the nozzle head 412. The processing liquid is then ejected from the nozzle head 412 toward the upper surface of the substrate W.

[0031] The substrate processing apparatus 1 discharges the processing liquid from the nozzle head 412 onto the center of the upper surface of the substrate W while rotating the substrate W using the rotation mechanism 30. The processing liquid spreads from the center to the periphery of the upper surface of the substrate W due to centrifugal force caused by the rotation of the substrate W. As a result, a liquid film of the processing liquid is formed on the upper surface of the substrate W.

[0032] The processing liquid may be, for example, a DHF cleaning liquid (dilute hydrofluoric acid), an SPM cleaning liquid, an SC-1 cleaning liquid, an SC-2 cleaning liquid, or pure water (deionized water). The SPM cleaning liquid is a mixture of sulfuric acid and hydrogen peroxide. The SC-1 cleaning liquid is a mixture of ammonia water, hydrogen peroxide, and pure water. The SC-2 cleaning liquid is a mixture of hydrochloric acid, hydrogen peroxide, and pure water. However, the type of processing liquid is not limited, and liquids other than those listed above may also be used.

[0033] The cup 50 is a mechanism for collecting the processing liquid after use. As shown in FIG. 1 , the cup 50 has an annular guide plate 51 that surrounds the substrate holding part 20. The cup 50 can be raised and lowered by a lifting mechanism (not shown). When the nozzle 41 ejects the processing liquid, the guide plate 51 surrounds the substrate W held by the substrate holding part 20. The processing liquid ejected from the nozzle 41 is supplied to the upper surface of the substrate W, and then scattered outward by centrifugal force caused by the rotation of the substrate W. The processing liquid scattered from the substrate W is then collected by the guide plate 51. The processing liquid collected by the guide plate 51 is discharged to the outside of the chamber 10 through a pipe (not shown).

[0034] The imaging device 60 is a device that captures an image of the state of the processing liquid supplied from the nozzle 41 to the substrate W. The imaging device 60 is located outside the chamber 10. As shown in FIG. 1 , the imaging device 60 includes an event-based camera 61, a high-speed camera 62, and a circuit board 63.

[0035] The event-based camera 61 and the high-speed camera 62 capture images of the interior of the chamber 10 through the window 15. Unlike a typical frame-based camera, the event-based camera 61 is a camera that captures only changes in brightness. The high-speed camera 62 captures images of the movement of the processing liquid to be observed at a timing based on the image data output from the event-based camera 61.

[0036] The circuit board 63 has electrical circuits for controlling the event-based camera 61 and the high-speed camera 62. The circuit board 63 is electrically connected to the event-based camera 61, the high-speed camera 62, and the control unit 70. The detailed configuration and functions of the imaging device 60 will be described later.

[0037] The control unit 70 is an information processing device that controls each part of the substrate processing apparatus 1. Fig. 3 is a control block diagram of the substrate processing apparatus 1. As conceptually shown in Fig. 3, the control unit 70 is configured by a computer having a processor 71 such as a CPU, a memory 72 such as a RAM, and a storage unit 73 such as a hard disk drive.

[0038] A computer program P is stored in the storage unit 73. As shown in Fig. 3, the control unit 70 is communicably connected to the above-mentioned chuck pin switching mechanism 23, motor 32, pump 416, valve 417, lifting mechanism for cup 50, and circuit board 63, respectively, via wire or wirelessly. The control unit 70 controls the operation of each of the above-mentioned units in accordance with the computer program P. This allows the cleaning process of the substrate W in the substrate processing apparatus 1 to proceed.

[0039] 2. Imaging Device Next, the imaging device 60 will be described in more detail. Below, a case will be described in which the imaging device 60 is used to observe the state of the processing liquid when the processing liquid discharged from the nozzle 41 first reaches the upper surface of the substrate W. Figures 4 and 5 are block diagrams showing the functions of the imaging device 60.

[0040] The event-based camera 61 is a camera that captures changes in brightness. A typical frame-based camera for capturing video outputs capture data in which frame images containing information on the brightness values ​​of a large number of pixels are arranged in chronological order. In contrast, the event-based camera 61 outputs first capture data D1 consisting of information only on pixels whose brightness values ​​have changed.

[0041] Specifically, the first photographic data D1 is composed of information about the coordinates of pixels whose luminance values ​​have changed, the time at which the luminance values ​​changed, and the direction of the change in luminance values. The direction of the change in luminance values ​​is binary information that is "1" when the luminance changes in a brighter direction and "0" when the luminance changes in a darker direction. Therefore, the amount of information in the first photographic data D1 output from the event-based camera 61 is much smaller than the amount of information in the photographic data output from a frame-based camera.

[0042] For this reason, the event-based camera 61 can acquire and transfer the first image capture data D1 at high speed. Furthermore, the event-based camera 61 can acquire the first image capture data D1 at time intervals shorter than the interval between frame images in a typical frame-based camera. The event-based camera 61 can acquire the first image capture data D1, for example, every few microseconds. Therefore, by using the event-based camera 61, changes in brightness within the field of view can be detected in real time.

[0043] As shown in Fig. 4, the event-based camera 61 is directed toward the vicinity of the tip of the nozzle 41. A region of interest R is set in a portion of the field of view of the event-based camera 61. In the example of Fig. 4, the region of interest R is the region between the nozzle head 412 and the substrate W and the portion close to the nozzle head 412.

[0044] The high-speed camera 62 is a frame-based camera for capturing video with a frame rate higher than that of a general frame-based camera. As shown in Fig. 5, the high-speed camera 62 is directed toward the center of the upper surface of the substrate W. In other words, the high-speed camera 62 is directed toward the position where the processing liquid discharged from the nozzle head 412 reaches the substrate W.

[0045] The high-speed camera 62 acquires second image data D2 by capturing an image of the top surface of the substrate W. While the frame rate of image data captured by a general frame-based camera is 30 to 60 frames per second, the frame rate of the second image data D2 captured by the high-speed camera 62 is several thousand frames per second or more. Therefore, the high-speed camera 62 can capture images of the high-speed movement of the processing liquid being supplied to the substrate W.

[0046] However, because the second photographing data D2 contains a large amount of information, the high-speed camera 62 cannot transfer the second photographing data D2 to an external device at the same time as photographing. For this reason, the high-speed camera 62 has an internal memory 621 for storing the second photographing data D2. While photographing an object, the high-speed camera 62 temporarily stores the obtained second photographing data D2 in the internal memory 621. Then, after photographing by the high-speed camera 62 is completed, the second photographing data D2 stored in the internal memory 621 is transferred from the internal memory 621 to the control unit 70 via the circuit board 63.

[0047] Therefore, the shooting time during which the high-speed camera 62 can continuously shoot is limited by the capacity of the built-in memory 621. The shooting time of the high-speed camera 62 is, for example, several tens of microseconds or less.

[0048] The circuit board 63 has electric circuits for controlling the event-based camera 61 and the high-speed camera 62. A field programmable gate array (FPGA) or a microcomputer is mounted on the circuit board 63. As shown in FIGS. 4 and 5 , the circuit board 63 has a data input unit 631, a timing determination unit 632, and a trigger output unit 633. The functions of the data input unit 631, the timing determination unit 632, and the trigger output unit 633 are realized by the FPGA or the microcomputer.

[0049] 6 is a flowchart showing the flow of the photographing operation by the imaging device 60. As shown in FIG. 6, when photographing is performed by the imaging device 60, first, photographing is started by the event-based camera 61 (step S1). The event-based camera 61 photographs the region of interest R below the nozzle head 412 described above. When no processing liquid is being ejected from the nozzle 41, there is no change in the brightness value in the region of interest R. Therefore, the first photographed data D1 is not output from the event-based camera 61.

[0050] Next, while continuing to capture images with the event-based camera 61, the control unit 70 opens the valve 417 and operates the pump 416. As a result, the processing liquid is supplied from the liquid supply source 414 through the piping 415 to the nozzle head 412. Then, the nozzle head 412 starts to discharge the processing liquid toward the top surface of the substrate W (step S2).

[0051] At this time, the time from when the control unit 70 sends a control signal to the valve 417 and the pump 416 until the nozzle head 412 starts discharging the treatment liquid varies by several tens of microseconds or more. For this reason, even if the high-speed camera 62 starts capturing images a certain time after the control unit 70 sends a control signal to the valve 417 and the pump 416, the time when the event to be captured occurs may be delayed by more than the capture time of the high-speed camera 62.

[0052] Therefore, the imaging device 60 uses the event-based camera 61 to determine the timing of capturing images with the high-speed camera 62. When the nozzle head 412 starts to eject the treatment liquid and the treatment liquid enters the region of interest R of the event-based camera 61 as shown in Figure 4, the event-based camera 61 outputs first captured data D1 that indicates a change in brightness in the region of interest R (step S3). The first captured data D1 output from the event-based camera 61 is input to the data input unit 631 of the circuit board 63.

[0053] The timing determination unit 632 determines the timing at which the discharge of the treatment liquid from the nozzle head 412 started based on the first photographing data D1 input to the data input unit 631 (step S4). In this embodiment, the start of the discharge of the treatment liquid from the nozzle head 412 is defined as the "first event" that serves as the reference for photographing timing. In step S4, the timing determination unit 632 determines the "first timing," which is the time at which the first event occurred, based on the first photographing data D1.

[0054] The trigger output unit 633 outputs a trigger signal T to the high-speed camera 62 based on the first timing determined by the timing determination unit 632. The trigger signal T is a signal indicating the "second timing," which is the time when the high-speed camera 62 should start capturing images. The second timing is set to be a predetermined time after the first timing. The trigger output unit 633 outputs the trigger signal T to the high-speed camera 62 at the second timing (step S5).

[0055] 5, when the high-speed camera 62 receives the trigger signal T, it starts capturing images (step S6). This makes it possible to capture an image of the processing liquid when it is discharged from the nozzle head 412 and first reaches the top surface of the substrate W.

[0056] In this embodiment, the first arrival of the processing liquid discharged from the nozzle head 412 on the upper surface of the substrate W is defined as the "second event." The second event occurs a predetermined time after the occurrence of the first event described above. The variation in the predetermined time is less than several tens of microseconds. Therefore, even if the image capturing time of the high-speed camera 62 is several tens of microseconds, the second event can be captured without missing an image by starting image capturing with the high-speed camera 62 at the second timing, which is a predetermined time after the first timing.

[0057] As described above, the imaging device 60 determines the first timing at which the first event occurred based on the first imaging data D1 output from the event-based camera 61. Then, based on the first timing, the high-speed camera 62 captures an image of the second event that occurs a predetermined time after the first event. This allows the high-speed camera 62, which has a short imaging time, to capture an image of the second event at an appropriate timing.

[0058] In particular, in this embodiment, the data input unit 631, timing determination unit 632, and trigger output unit 633 are configured not by a computer but by an FPGA or a microcomputer. Therefore, compared to when a computer is used, after the first photographed data D1 is acquired, the trigger signal T can be output to the high-speed camera 62 more quickly. This makes it possible to further reduce the risk of the high-speed camera 62 missing the second event.

[0059] 3. Modifications Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

[0060] 7 is a block diagram showing the functions of an imaging device 60 according to a first modification. In the above embodiment, the imaging device 60 is used in the substrate processing apparatus 1 to observe the state of the processing liquid being ejected from the nozzles 41 onto the substrate W. However, as shown in FIG. 7 , the imaging device 60 may also be used in an inkjet printing apparatus to observe the state of ink being ejected onto printing paper 9 from nozzles formed on the underside of an inkjet head 80.

[0061] In this case, the start of ink ejection from the nozzles of the inkjet head 80 may be considered a "first event," and the arrival of ink ejected from the nozzles on the top surface of the printing paper 9 may be considered a "second event." The event-based camera 61 photographs the ink ejected from the nozzles in the vicinity of the nozzles. The timing determination unit 632 determines the time when ink is ejected from the nozzles as the "first timing" based on the first imaging data D1 output from the event-based camera 61. Then, the high-speed camera 62 photographs the ink reaching the printing paper 9 at a second timing that is a predetermined time after the first timing.

[0062] As in the above embodiment and the first modified example, the imaging device 60 is suitable for observing the state of liquid being ejected from a nozzle onto an object.

[0063] 8 is a block diagram showing the functions of an imaging device 60 according to a second modification. As shown in Fig. 8, the imaging device 60 may be used in the substrate processing apparatus 1 to observe how a liquid ejected onto the upper surface of the substrate W spreads along the upper surface of the substrate W.

[0064] In this case, for example, the arrival of the treatment liquid at a midpoint between the center and the outer edge of the substrate W may be defined as a "first event," and the arrival of the treatment liquid at the outer edge of the substrate W may be defined as a "second event." The event-based camera 61 photographs the treatment liquid at a midpoint of the substrate W. The timing determination unit 632 determines, based on the first photographed data D1 output from the event-based camera 61, the time at which the treatment liquid reaches the midpoint of the substrate W as the "first timing." Then, the high-speed camera 62 photographs the ink that has reached the outer edge of the substrate W at a second timing that is a predetermined time after the first timing.

[0065] This allows the high-speed camera 62 to photograph the state of the processing liquid at the moment the processing liquid reaches the outer edge of the substrate W.

[0066] <3-3. Other Modifications> In the above embodiment, the timing determination unit 632 determines the first timing by assuming that the first event has occurred when the first photographed data D1 is input to the data input unit 631. However, the timing determination unit 632 may determine the first timing only when the input first photographed data D1 satisfies a predetermined condition.

[0067] For example, the timing determination unit 632 may determine the first timing by assuming that the first event has occurred when the number of pixels whose luminance values ​​have changed in the first photographed data D1 is equal to or greater than a predetermined threshold. Alternatively, the timing determination unit 632 may determine the first timing by assuming that the first event has occurred when a specific pattern appears in the first photographed data D1. These processes can reduce false detection of the first event.

[0068] In the above embodiment, the data input unit 631, the timing determination unit 632, and the trigger output unit 633 are configured by an FPGA or a microcomputer. However, as long as the trigger signal T can be output with accuracy within an allowable range, the data input unit 631, the timing determination unit 632, and the trigger output unit 633 may be configured by a computer. For example, the functions of the data input unit 631, the timing determination unit 632, and the trigger output unit 633 may be incorporated into the control unit 70 of the substrate processing apparatus 1.

[0069] Furthermore, the elements appearing in the above-described embodiments and modifications may be combined in any manner as long as no contradictions arise.

[0070] 1: Substrate processing apparatus 9: Printing paper 10: Chamber 15: Window section 20: Substrate holding section 30: Rotation mechanism 40: Processing liquid supply section 41: Nozzle 50: Cup 60: Imaging device 61: Event-based camera 62: High-speed camera 63: Circuit board 70: Control section 80: Inkjet head 411: Nozzle arm 412: Nozzle head 414: Liquid supply source 415: Piping 416: Pump 417: Valve 621: Built-in memory 631: Data input section 632: Timing determination section 633: Trigger output section D1: First photographed data D2: Second photographed data R: Region of interest T: Trigger signal W: Substrate

Claims

1. An imaging device comprising: an event-based camera; a high-speed camera; and a timing determination unit that determines a first timing at which a first event occurs based on first imaging data output from the event-based camera, wherein a second event that occurs a predetermined time after the first event is captured by the high-speed camera based on the first timing.

2. An imaging device according to claim 1, wherein the timing determination unit determines the timing at which the number of pixels whose luminance values ​​have changed in the first shooting data is equal to or greater than a predetermined threshold as the first timing.

3. An imaging device according to claim 1, wherein the timing determination unit determines the timing at which a specific pattern appears in the first photographic data as the first timing.

4. An imaging device according to any one of claims 1 to 3, further comprising a trigger signal output unit that outputs a trigger signal to the high-speed camera based on the first timing determined by the timing determination unit.

5. An imaging device according to claim 4, wherein the timing determination section and the trigger signal output section are configured by an FPGA or a microcomputer.

6. An imaging device as claimed in any one of claims 1 to 3, used to observe the state of liquid being ejected from a nozzle onto an object, wherein the event-based camera photographs the liquid being ejected from the nozzle near the tip of the nozzle, the timing determination unit determines the time when the ejection of liquid from the nozzle begins as the first timing based on the first imaging data, and the high-speed camera photographs the liquid reaching the object a predetermined time after the first timing.

7. An imaging device as claimed in any one of claims 1 to 3, used to observe the state of a liquid spreading on the surface of a substrate, wherein the event-based camera photographs a midpoint between the centre and the outer edge of the substrate, the timing determination unit determines the time at which the liquid reaches the midpoint as the first timing based on the first imaging data, and the high-speed camera photographs the liquid reaching the outer edge of the substrate a predetermined time after the first timing.

Images