Zoetrope system

Abstract

A zoetrope system in an embodiment of the present invention uses a water droplet generation device for dropping a liquid and a projector for projecting light and displaying a video. The zoetrope system includes a control unit and a processor. The control unit is configured so as to be able to control whether or not the projection light of the projector is irradiated to a range in which the liquid is dropped by the water droplet generation device. The processor is configured to set a first frequency at which the water droplet generation device drops the liquid and a second frequency at which the control unit irradiates the range with the projection light. The processor sets the second frequency to an integer multiple of the first frequency.

Description

Zoetrope System

[0001] The embodiment relates to a zoetrope system with projection onto a periodically moving object such as a falling drop of water.

[0002] A zoetrope system has been proposed, which creates the perception of animation by rotating multiple objects on a circular disk and periodically illuminating them with a strobe light. Another known technique involves periodically illuminating falling water droplets with a strobe light or projector, thereby visualizing their shapes. These techniques allow users to perceive the droplets as if they were stationary in mid-air, falling at a variable speed, or ascending in an orbit. For example, if the light illumination duration is longer than a certain time (e.g., 1 millisecond), the droplets appear elongated and cylindrical in the direction of their fall, and the user cannot perceive them as spherical. On the other hand, if the light illumination duration is shorter than this time, the user can perceive them as spherical. In other words, to perceive spherical droplets using this technique, a high-speed projector with an image refresh rate of approximately 1000 Hz, i.e., a light illumination duration of approximately 1 millisecond, is required.

[0003] SADAM FUJIOKA, ““drop”: An Interactive Art Installation withWaterdrop Projection-Mapping”, Proceedings of the ACM on Computer Graphics and Interactive Techniques, Vol.4, No.2, Article 27, August 2021

[0004] However, when using a high-speed projector, there are problems such as the high cost of the equipment and the time and effort required to create the images to be displayed.

[0005] The present invention has been made in light of the above-mentioned circumstances, and its object is to provide a zoetrope system that allows a user to visually recognize spherical water droplets using a projector with a normal refresh rate (for example, 240 Hz or less).

[0006] The zoetrope system of the embodiment utilizes a droplet generation device that drips liquid and a projector that projects light to display an image. The zoetrope system includes a control unit and a processor. The control unit is configured to control whether or not the projection light of the projector is irradiated onto an area onto which the liquid is dripped by the droplet generation device. The processor is configured to set a first frequency at which the droplet generation device drips liquid and a second frequency at which the control unit irradiates the area with the projection light. The processor sets the second frequency to an integer multiple of the first frequency.

[0007] According to the embodiment, a zoetrope system can be provided that uses a projector with a normal refresh rate to allow a user to visually recognize spherical water droplets.

[0008] FIG. 1 is a block diagram showing an example of the overall configuration of a zoetrope system according to the first embodiment. FIG. 2 is a block diagram showing an example of the configuration of a water droplet generating device included in the zoetrope system according to the first embodiment. FIG. 3 is a block diagram showing an example of the configuration of a projector included in the zoetrope system according to the first embodiment. FIG. 4 is a block diagram showing an example of the configuration of a control device included in the zoetrope system according to the first embodiment. FIG. 5 is a schematic diagram showing an example of the functional configuration of a zoetrope system according to the first embodiment. FIG. 6 is a time chart showing an example of a method for controlling a shutter in the zoetrope system according to the first embodiment. FIG. 7 is a schematic diagram showing an example of a method for projecting water droplets in the zoetrope system according to the first embodiment. FIG. 8 is a schematic diagram showing an example of a method for controlling the projection range in the zoetrope system according to the first embodiment. FIG. 9 is a schematic diagram showing an example of the result of water droplet projection by the zoetrope system according to the first embodiment. FIG. 10 is a schematic diagram showing an example of the functional configuration of a zoetrope system according to the second embodiment. FIG. 11 is a schematic diagram showing an example of the functional configuration of a zoetrope system according to the third embodiment. Fig. 12 is a schematic diagram showing an example of the functional configuration of a zoetrope system according to a fourth embodiment. Fig. 13 is a schematic diagram showing an example of the functional configuration of a zoetrope system according to a fifth embodiment. Fig. 14 is a schematic diagram showing an example of the projection result of water droplets by the zoetrope system according to the fifth embodiment. Fig. 15 is a schematic diagram showing an example of the functional configuration of a zoetrope system according to a sixth embodiment.

[0009] Each embodiment will be described below with reference to the drawings. Each embodiment illustrates an apparatus or method for embodying the technical idea of ​​the invention. The drawings are schematic or conceptual. In the following, the same reference numerals are used to designate components having substantially the same functions and configurations. A "hyphen + number" following a number constituting a reference numeral is used to distinguish between elements that are referred to by reference numerals containing the same number and have similar configurations.

[0010] <1> First Embodiment The zoetrope system 1 according to the first embodiment is configured to use a shutter that transmits light at a certain frequency to adjust the irradiation time of light from the projector. Details of the zoetrope system 1 according to the first embodiment will be described below.

[0011] <1-1> Configuration First, the configuration of the zoetrope system 1 according to the first embodiment will be described.

[0012] <1-1-1> Overall Configuration of Zoetrope System 1 Fig. 1 is a block diagram showing an example of the overall configuration of the zoetrope system 1 according to the first embodiment. As shown in Fig. 1, the zoetrope system 1 includes a water droplet generation device 10, a projector 20, a shutter 30, and a control device 40.

[0013] The water droplet generation device 10 is configured to cause water droplets to fall from a nozzle at a constant frequency. The projector 20 projects light to display an image. The projector 20 supports a refresh rate of, for example, 240 Hz or less. The projector 20 is positioned so that the falling trajectory of the water droplets generated by the water droplet generation device 10 is included in the projection range. The shutter 30 is positioned in front of the projector 20 and has the function of transmitting and blocking incident light. The shutter 30 is configured to transmit the incident light, which is projected light from the projector 20, at a constant frequency. The shutter 30 is composed of, for example, a liquid crystal shutter or a rotating body with slits. The control device 40 controls the overall operation of the zoetrope system 1. For example, the control device 40 can control the operating frequencies of the water droplet generation device 10 and the shutter 30, and the image projected by the projector 20.

[0014] <1-1-2> Configuration of the Water Droplet Generation Device 10 Fig. 2 is a block diagram showing an example of the configuration of the water droplet generation device 10 provided in the zoetrope system 1 according to the first embodiment. As shown in Fig. 2, the water droplet generation device 10 includes a water storage tank 11, a pump 12, a nozzle 13, and a vibrator 14.

[0015] The water storage tank 11 is configured to be able to store water (liquid). The pump 12 sucks up water in the water storage tank 11 and supplies it to the nozzles 13. The nozzles 13 are configured to drip the water supplied from the water storage tank 11 in response to the vibration of the vibrator 14. The vibrator 14 vibrates at a constant frequency under the control of the control device 40 so that water drips from the nozzles 13. Note that the water droplet generating device 10 may have multiple nozzles 13 and may drop water droplets from each of the multiple nozzles 13. The multiple nozzles 13 may be aligned along the projection surface of the projector 20, or some of the multiple nozzles 13 may be arranged offset in the depth direction relative to the projection surface.

[0016] <1-1-3> Configuration of the projector 20 Fig. 3 is a block diagram showing an example of the configuration of the projector 20 provided in the zoetrope system 1 according to the first embodiment. As shown in Fig. 2, the projector 20 includes a light source 21, an illumination optical system 22, a liquid crystal panel 23, and a projection lens 24.

[0017] The light source 21 generates light with which the projector 20 generates an image. The light source 21 is, for example, a mercury lamp, a laser light source, or an LED (Light Emitting Diode). The light source 21 may also be called a backlight. The illumination optical system 22 guides light emitted from the light source 21 to the liquid crystal panel 23. The liquid crystal panel 23 transmits or reflects the light incident from the illumination optical system 22 and guides it to the projection lens 24. The projection lens 24 magnifies the incident light and projects it outside the projector 20. In this specification, the light projected from the projection lens 24 is referred to as projection light PL.

[0018] A color separation system that separates incident light into the three primary colors (red, green, and blue) may be disposed between the illumination optical system 22 and the LCD panel 23, and a color synthesis system that synthesizes the incident light of the three primary colors that have passed through the LCD panel 23 may be disposed between the LCD panel 23 and the projection lens 24. The projector 20 included in the zoetrope system 1 is not limited to the LCD system described above. The zoetrope system 1 cannot use a projector that expresses colors through time-division superimposition, such as a one-chip DLP (Digital Light Processing) system, but rather uses a projector that simultaneously projects the three primary colors. For example, the zoetrope system 1 may use a three-chip DLP projector 20.

[0019] <1-1-4> Configuration of the control device 40 Fig. 4 is a block diagram showing an example of the configuration of the control device 40 provided in the zoetrope system 1 according to the first embodiment. As shown in Fig. 2, the control device 40 includes, for example, a CPU (Central Processing Unit) 41, a ROM (Read Only Memory) 42, a RAM (Random Access Memory) 43, a communication module 44, and a storage device 45.

[0020] The CPU 41 is a processor capable of executing various programs and controls the overall operation of the zoetrope system 1. The ROM 42 is, for example, a non-volatile semiconductor memory and stores programs and control data for controlling the zoetrope system 1. The RAM 43 is, for example, a volatile semiconductor memory and is used as a work area for the CPU 41. The communication module 44 is a communication circuit configured to be able to send control signals to each of the water droplet generation device 10, the projector 20, and the shutter 30. The storage device 45 stores, for example, image data to be projected onto the water droplet WD.

[0021] <1-1-5> Functional Configuration of Zoetrope System 1 Fig. 5 is a schematic diagram showing an example of the functional configuration of the zoetrope system 1 according to the first embodiment. Fig. 5 shows projection light PL from the projector 20 passing through the shutter 30 and illuminating one of the multiple water droplets WD dropped from the nozzle 13 of the water droplet generation device 10. As shown in Fig. 5, the control device 40 includes, for example, a drop timing control unit 401, an illumination timing control unit 402, and a projection image control unit 403.

[0022] The drip timing control unit 401 controls the operating frequency of the vibrator 14 of the water droplet generation device 10, thereby controlling the timing at which the water droplets WD are dripped from the nozzle 13. Hereinafter, the frequency at which the water droplets WD are dripped from the nozzle 13 will be referred to as the "drop frequency."

[0023] The illumination timing control unit 402 controls the timing at which the projection light PL of the projector 20 is transmitted or blocked by controlling the operating frequency of the shutter 30. Hereinafter, the frequency at which the shutter 30 transmits or blocks the projection light PL is referred to as the "illumination frequency." The illumination timing control unit 402 sets the illumination frequency to an integer multiple of the drip frequency.

[0024] The projection image control unit 403 holds image data to be displayed by the projector 20, and inputs the image data to the projector 20. The projection image control unit 403 may acquire the image data to be input to the projector 20 via a network.

[0025] Hereinafter, the direction in which the water droplets WD are dropped by the water droplet generation device 10 will be referred to as the first direction D1. The direction in which the water droplets WD are viewed by the user will be referred to as the second direction D2. The second direction D2 corresponds to, for example, the direction in which the projection light PL of the projector 20 is viewed from the front. The user can view the water droplets WD contained in the area irradiated by the projection light PL. In FIG. 5, the range in which the water droplets WD can be viewed by the user is shown as a viewable range VR.

[0026] <1-2> Operation Next, the operation of the zoetrope system 1 according to the first embodiment will be described.

[0027] <1-2-1> Control Method of the Shutter 30 FIG. 6 is a time chart showing an example of a control method of the shutter 30 in the zoetrope system 1 according to the first embodiment. In the zoetrope system 1, the shutter 30 periodically transmits the projection light PL as shown in FIG. 6. Specifically, one cycle of the shutter 30's operation includes a time T1 during which the projection light PL is transmitted and a time T2 during which the projection light PL is blocked. The time T1 corresponds to the irradiation time of the water droplets WD and is 2 milliseconds or less. In other words, the illumination timing control unit 402 sets the duty ratio of transmission and blocking by the shutter 30 so that the time during which the projection light PL is transmitted is 2 milliseconds or less.

[0028] <1-2-2> Method for Projecting Water Droplets WD FIG. 7 is a schematic diagram showing an example of a method for projecting water droplets WD in the zoetrope system 1 according to the first embodiment. The dripping frequency and illumination frequency settings are different in each of (A), (B), and (C) of FIG. 7. (A) of FIG. 7 corresponds to a setting where the dripping frequency is F1 and there is no illumination. (B) of FIG. 7 corresponds to a setting where both the dripping frequency and the illumination frequency are F1. (C) of FIG. 7 corresponds to a setting where the dripping frequency is F1 and the illumination frequency is F2. In this example, F2 is twice the frequency of F1.

[0029] 7A, when the drop frequency is F1 and there is no illumination, water droplets WD are dropped at a constant frequency F1 from the nozzle 13. In this example, the distance in the drop direction between two successively dropped water droplets WD is L1.

[0030] 7B , when the dropping frequency and the illumination frequency are both F1, water droplets WD are dropped from the nozzle 13 at a constant frequency F1, and the projector 20 irradiates projection light PL at the constant frequency F1. When light at frequency F1 is irradiated for a short time (e.g., 2 milliseconds) on the water droplets WD falling at frequency F1, the user can visually perceive the water droplets WD as if they are not falling but are floating in the air with the spacing between adjacent water droplets WD maintained. When the dropping frequency and the illumination frequency are the same, the water droplets WD are visually perceived as stationary with the spacing (L1) between the falling water droplets WD being the same as the actual spacing between them.

[0031] 7C , when the dropping frequency is F1 and the illumination frequency is F2, water droplets WD are dropped from the nozzle 13 at a constant frequency F1, and the projector 20 irradiates projection light PL at a constant frequency F2. When light at frequency F2 is irradiated for a short time (e.g., 2 milliseconds) onto the water droplets WD falling at frequency F1, the user can visually recognize that the water droplets WD do not fall but appear to be floating in the air with the spacing between adjacent water droplets WD maintained at L2, half the spacing when the illumination frequency is F1.

[0032] In this way, the zoetrope system 1 can increase the number of visible water droplets WD by increasing the illumination frequency to an integer multiple of the dripping frequency. In other words, by increasing the illumination frequency to an integer multiple of the dripping frequency, the water droplets WD can be perceived as floating at intervals shorter than the actual distance between the falling water droplets WD. Specifically, when the dripping frequency is N times the illumination frequency, the water droplets WD are perceived as stationary at intervals 1 / N of the actual interval between the falling water droplets WD.

[0033] <1-2-1> Projection Range Control Method FIG. 8 is a schematic diagram showing an example of a projection range control method in the zoetrope system 1 according to the first embodiment. As shown in FIG. 8, the zoetrope system 1 may control the illumination frequency to N times the dripping frequency and then further control the projection range. The zoetrope system 1 can change the position of light irradiation on the falling trajectory of the water droplets WD, allowing the user to visually perceive the water droplets WD as floating at any position on the falling trajectory. Control of the projection range can be achieved by projecting an image from the projector in which the areas to be shaded are black.

[0034] FIG. 9 is a schematic diagram illustrating an example of the projection result of water droplets WD by the zoetrope system 1 according to the first embodiment. FIG. 9 illustrates an extracted field of view FOV viewed from a second direction D2 perpendicular to the projection surface of the projector 20. The illustrated third direction D3 corresponds to a direction parallel to the projection surface of the projector 20 and perpendicular to the first direction D1 (dropping direction). As shown in FIG. 9 , the field of view FOV includes a row range CR of water droplets WD dropped by the water droplet generation device 10. In this example, the projection range control shown in FIG. 8 is applied. Therefore, in the row range CR, two regions where the water droplets WD appear to be floating are formed, separated from each other in the first direction D1.

[0035] <1-3> Effects of the First Embodiment As described above, the zoetrope system 1 according to the first embodiment uses the shutter 30 to convert the light from the projector 20 into short-term (2 milliseconds or less) periodic illumination with a frequency that is an integer multiple of the falling speed of the water droplets WD. As a result, even when using a projector 20 with a normal refresh rate (240 Hz or less), the zoetrope system 1 according to the first embodiment can allow the user to view the water droplets WD while maintaining their spherical shape and stationary on their falling trajectory. Furthermore, the zoetrope system 1 according to the first embodiment allows the user to view the water droplets WD in any position by using the projector 20 to irradiate light only on the desired location of the water droplets WD.

[0036] <2> Second Embodiment In the second embodiment, the function of the shutter 30 described in the first embodiment is realized by controlling the light source 21 of the projector 20. Below, details of the zoetrope system 1A according to the second embodiment will be described, focusing on the differences from the first embodiment.

[0037] <2-1> Configuration Fig. 10 is a schematic diagram showing an example of the functional configuration of a zoetrope system 1A according to the second embodiment. As shown in Fig. 10, the zoetrope system 1A includes a water droplet generation device 10, a projector 20A, and a control device 40A, and does not have a shutter 30. The projector 20A includes a light source control unit 201 and a projection unit 202. The control device 40A includes a drop timing control unit 401, an illumination timing control unit 402A, and a projection image control unit 403.

[0038] The illumination timing control unit 402A notifies the light source control unit 201 of the illumination frequency. Based on the illumination frequency notified by the illumination timing control unit 402A, the light source control unit 201 controls the light source 21 of the projection unit 202 to generate light at a constant frequency. The projection unit 202 is a combination of the light source 21, illumination optical system 22, liquid crystal panel 23, and projection lens 24, all of which are not shown. The projection unit 202 generates projection light PL based on image data input from the projection image control unit 403, at an illumination frequency based on the control of the light source control unit 201. The other configurations of the zoetrope system 1A according to the second embodiment are the same as those of the zoetrope system 1 according to the first embodiment.

[0039] <2-2> Operation Next, referring to FIG. 10 , the operation of the zoetrope system 1A according to the second embodiment will be described. The light source control unit 201 executes control in which the transmission and blocking states shown in FIG. 6 are replaced with on and off, respectively. That is, in the zoetrope system 1A, the light source control unit 201 periodically turns on the light source 21. Time T1 in the second embodiment corresponds to the time during which the projector 20 generates the projection light PL, i.e., the time during which the light source control unit 201 turns on the light source 21. Time T2 in the second embodiment corresponds to the time during which the projector 20 does not generate the projection light PL, i.e., the time during which the light source control unit 201 turns off the light source 21. The light source control unit 201 then sets the on / off duty ratio of the light source 21 so that the time during which the projection light PL is generated is 2 milliseconds or less. The remaining operation of the zoetrope system 1A according to the second embodiment is the same as that according to the first embodiment.

[0040] <2-3> Effects of the Second Embodiment As described above, the zoetrope system 1A according to the second embodiment controls the irradiation time and frequency using a light source control unit 201 that controls the backlight (light source 21) instead of the shutter 30 described in the first embodiment. As a result, the zoetrope system 1A according to the second embodiment can allow the user to visually recognize spherical water droplets using a projector 20A with a normal refresh rate, just like the first embodiment.

[0041] <3> Third Embodiment In the third embodiment, the same effect as increasing the illumination frequency is achieved by operating multiple projection units 202 at different phases. Below, details of the zoetrope system 1B according to the third embodiment will be described, focusing on differences from the first and second embodiments.

[0042] <3-1> Configuration FIG. 11 is a schematic diagram showing an example of the functional configuration of a zoetrope system 1B according to the third embodiment. As shown in FIG. 11, the zoetrope system 1B includes a water droplet generation device 10, multiple projection units PU, and a control device 40A. The projection unit PU corresponds to a pair of a projection unit 202 and a shutter 30, or a pair of a projection unit 202 and a light source control unit 201. FIG. 11 illustrates a case in which the zoetrope system 1B includes two projection units PU1 and PU2. The control device 40B includes a drop timing control unit 401, an illumination timing control unit 402B, and a projection image control unit 403A.

[0043] Each of the projection units PU1 and PU2 is configured to operate independently under the control of the illumination timing control unit 402B. In the third embodiment, the projection units PU1 and PU2 are installed in approximately the same position. For example, the projection units PU1 and PU2 are arranged adjacent to each other, with the optical axis of the projection unit PU1 parallel to the optical axis of the projection unit PU2. This causes the projection light PL1 from the projection unit PU1 and the projection light PL2 from the projection unit PU2 to irradiate approximately the same area. The illumination timing control unit 402B is configured to control each of the projection units PU1 and PU2 with the same illumination frequency but different phases. The projected image control unit 403A inputs image data to each of the projection units PU1 and PU2. The other configurations of the zoetrope system 1B according to the third embodiment are the same as those of the first or second embodiment.

[0044] <3-2> Operation Next, the operation of the zoetrope system 1B according to the third embodiment will be described with reference to Fig. 11 . The illumination timing control unit 402B controls the phase of the illumination frequency of the projection light PL1 of the projection unit PU1 and the phase of the illumination frequency of the projection light PL2 of the projection unit PU2, for example, by shifting them by half. In this example, the water droplets WD irradiated by the projection light PL1 correspond to the water droplets WD hatched with thin lines in Fig. 11 , and the water droplets WD irradiated by the projection light PL2 correspond to the water droplets WD hatched with thick lines in Fig. 11 .

[0045] By shifting the phase by ½, one water droplet WD illuminated by projection light PL2 is positioned between two adjacent water droplets WD illuminated by projection light PL1. In other words, when the dripping frequency and illumination frequency of projection units PU1 and PU2 are both F1, the user can visually recognize the water droplets WD at the same intervals as when the dripping frequency is F1 and the illumination frequency is F2 as described in the first embodiment.

[0046] Note that when the number of projection units PU is n, the illumination timing control unit 402B shifts the phases of the illumination frequencies of the n projection units PU by 1 / n each. As a result, between two adjacent water droplets WD illuminated by the projection light PL of a certain projection unit PU, (n-1) water droplets WD illuminated by the projection light of another projection unit PU are positioned. Other operations of the zoetrope system 1A according to the third embodiment are the same as those of the first or second embodiment.

[0047] <3-3> Effects of the Third Embodiment As described above, the zoetrope system 1B according to the third embodiment has multiple projection units PU, and the illumination timing control unit 402B controls the illumination time and frequency of each of the multiple projection units PU. This makes it possible for the zoetrope system 1B according to the third embodiment to increase the visible density of the water droplets WD even in cases where the dripping frequency of the water droplets WD is low and the visible density of the water droplets WD cannot be increased even by increasing the frequency of the light source control unit 201 to the limit of the response speed of the light source 21 in a single projection unit PU. In other words, by increasing the number of projection units PU, the zoetrope system 1B according to the third embodiment can achieve the same effects as the first embodiment and can also increase the visible density of the water droplets WD.

[0048] <4> Fourth Embodiment In the fourth embodiment, the visible range VR is expanded by operating multiple projection units 202 at different positions. Below, details of the zoetrope system 1C according to the fourth embodiment will be described, focusing on differences from the first to third embodiments.

[0049] <4-1> Configuration FIG. 12 is a schematic diagram showing an example of the functional configuration of a zoetrope system 1C according to the fourth embodiment. As shown in FIG. 12, the zoetrope system 1C includes a water droplet generation device 10, multiple projection units PU, and a control device 40C. The configuration of the projection unit PU in the fourth embodiment is the same as that in the third embodiment. FIG. 12 illustrates a case in which the zoetrope system 1C includes two projection units PU1 and PU2. The control device 40C includes a drop timing control unit 401, an illumination timing control unit 402C, and a projection image control unit 403A.

[0050] Each of the projection units PU1 and PU2 is configured to be able to operate independently based on the control of the illumination timing control unit 402B. In the fourth embodiment, the projection units PU1 and PU2 are installed separately. The projection light PL1 of the projection unit PU1 and the projection light PL2 of the projection unit PU2 intersect. Note that the projection lights PL1 and PL2 intersect when the optical axis of the projection unit PU1 and the optical axis of the projection unit PU2 are not parallel. The illumination timing control unit 402C is configured to control each of the projection units PU1 and PU2 with the same illumination frequency and the same phase. In other words, the illumination timing control unit 402C synchronizes the illumination timing of the multiple projection units PU1. The remaining configuration of the zoetrope system 1C according to the fourth embodiment is the same as that of the third embodiment.

[0051] <4-2> Operation Next, referring to FIG. 12 , the operation of the zoetrope system 1C according to the fourth embodiment will be described. In the zoetrope system 1C, the illumination timing of the multiple projection units PU1 and PU2 is synchronized, so that the water droplets WD can be illuminated by the projection lights PL1 and PL2 at the same time. As a result, the user can view the water droplets WD in the visibility range VR, which is the combination of the visibility range VR1 of the projection unit PU1 and the visibility range VR2 of the projection unit PU2. Other operations of the zoetrope system 1C according to the fourth embodiment are the same as those of the first or second embodiment.

[0052] <4-3> Effects of the Fourth Embodiment As described above, the zoetrope system 1C according to the fourth embodiment has multiple projection units PU arranged in different positions, and the illumination timing control unit 402C synchronizes the illumination timing of each of the multiple projection units PU. This allows the zoetrope system 1C according to the fourth embodiment to increase the visible range of the water droplets WD depending on the number and arrangement of the projection units PU. Therefore, by increasing the number of projection units PU, the zoetrope system 1C according to the fourth embodiment can achieve the same effects as the first embodiment and can also expand the visible range of the water droplets WD.

[0053] <5> Fifth Embodiment In the fifth embodiment, an image is projected onto a plane by dropping water droplets WD using a plurality of nozzles 13. Below, details of the zoetrope system 1D according to the fifth embodiment will be described, focusing on the differences from the first to fourth embodiments.

[0054] <5-1> Configuration FIG. 13 is a schematic diagram showing an example of the functional configuration of a zoetrope system 1D according to the fifth embodiment. As shown in FIG. 13, the zoetrope system 1D includes a water droplet generation device 10A, a projection unit PU, and a control device 40D. The water droplet generation device 10A includes a plurality of nozzles 13. The control device 40D includes a drop timing control unit 401A, an illumination timing control unit 402C, and a projection image control unit 403B. The configuration of the projection unit PU in the fifth embodiment is the same as that in the third embodiment.

[0055] 13 illustrates an example in which the zoetrope system 1D includes four nozzles 13-1, 13-2, 13-3, and 13-4 aligned in the third direction D3. Although not shown, water (liquid) is supplied to each of the plurality of nozzles 13 from a water storage tank 11 by a pump 12. Vibrators 14 are provided corresponding to each of the plurality of nozzles 13. Note that in the fifth embodiment, the positions of some of the plurality of nozzles 13 may be shifted in the second direction D2 (depth direction).

[0056] The drip timing control unit 401A controls the timing at which water is dripped from each of the plurality of nozzles 13. Specifically, the drip timing control unit 401A vibrates the vibrators 14 associated with each of the plurality of nozzles 13 at a predetermined drip frequency, thereby causing water to drip from each of the plurality of nozzles 13. The illumination timing control unit 402C controls the illumination frequency, thereby controlling the timing at which the projector 20 emits projection light PL (not shown). The projection image control unit 403B holds image data to be displayed by the projection unit PU, and inputs the image data to the projection unit PU.

[0057] <5-2> Operation Next, the operation of the zoetrope system 1D according to the fifth embodiment will be described with reference to FIG. 13. In the zoetrope system 1D, the illumination timing control unit 402C controls the projection unit PU at an illumination frequency that is an integer multiple of the dripping frequency of each of the nozzles 13-1 to 13-4. This allows the user to view stationary water droplets WD on planes parallel to each of the first direction D1 and the third direction D3.

[0058] FIG. 14 is a schematic diagram illustrating an example of the water droplet projection results obtained by the zoetrope system 1D according to the fifth embodiment. FIG. 14 illustrates an extracted field of view FOV viewed from the second direction D2. As shown in FIG. 14, the field of view FOV includes multiple row ranges CR1 to CR4, each including a water droplet WD dropped by the nozzles 13-1 to 13-4 of the water droplet generation device 10A. Furthermore, in this example, the projection range control shown in FIG. 8 is also applied. Therefore, within the row ranges CR1 to CR4, two regions in which the water droplets WD appear to be floating are formed, separated in the first direction D1.

[0059] In the zoetrope system 1D, if the water droplet generation device 10A includes nozzles 13 arranged with offsets in the second direction D2, the projection image control unit 403B divides the image data projected by the projection unit PU into groups of nozzles 13 arranged with offsets in the second direction D2. The projection image control unit 403B then inputs the divided image data into the projection unit PU for each corresponding column range. This allows the zoetrope system 1D to project images onto water droplets WD arranged at different positions in the depth direction (second direction D2). Other operations of the zoetrope system 1D according to the fifth embodiment are the same as those of the first or second embodiment.

[0060] <5-3> Effects of the Fifth Embodiment As described above, the zoetrope system 1D according to the fifth embodiment irradiates multiple rows of water droplets WD generated by a water droplet generation device 10A having multiple nozzles 13 with projection light PL from a projection unit PU, in the same manner as in the first or second embodiment. This allows the user to view an image projected onto the water droplets WD arranged on a flat surface (projection surface). Furthermore, when the multiple nozzles 13 include nozzles 13 arranged with a shift in the depth direction, the user can view an image projected onto the water droplets D arranged with a depth.

[0061] <6> Sixth Embodiment In the sixth embodiment, the dripping frequency and the lighting frequency are dynamically controlled according to the content to be projected. The following describes the details of the zoetrope system 1E according to the sixth embodiment, focusing on the differences from the first to fifth embodiments.

[0062] <6-1> Configuration Fig. 15 is a schematic diagram showing an example of the functional configuration of a zoetrope system 1E according to the sixth embodiment. As shown in Fig. 15, the zoetrope system 1E includes a water droplet generation device 10, a projection unit PU, and a control device 40E. The control device 40E includes a drop timing control unit 401, an illumination timing control unit 402, a projected image control unit 403, an image storage unit 404, an image analysis unit 405, and a frequency control unit 406. The configuration of the projection unit PU in the sixth embodiment is the same as that in the third embodiment.

[0063] The video storage unit 404 stores video data corresponding to the content to be projected and outputs the video data to the projection video control unit 403 and the video analysis unit 405. The video analysis unit 405 analyzes the video data received from the video storage unit 404. The video analysis unit 405 then outputs the analysis results to the frequency control unit 406. The frequency control unit 406 sets a dripping frequency and an illumination frequency according to the analysis results received from the video analysis unit 405. The frequency control unit 406 then outputs the set dripping frequency and illumination frequency to the drip timing control unit 401 and the illumination timing control unit 402, respectively. The dripping timing control unit 401 controls the water droplet generation device 10 according to the drip frequency setting received from the frequency control unit 406. The illumination timing control unit 402 controls the projection unit PU according to the illumination frequency setting received from the frequency control unit 406. The other configurations of the zoetrope system 1E according to the sixth embodiment are the same as those of the first or second embodiment.

[0064] <6-2> Operation Next, referring to FIG. 15, the operation of the zoetrope system 1E according to the sixth embodiment will be described. The zoetrope system 1E according to the sixth embodiment changes the settings of the drip timing control unit 401 and the illumination timing control unit 402 according to the content (analysis result) of the video data. For example, the video analysis unit 405 calculates the density of the projected video. Then, the frequency control unit 406 sets the drip frequency to a low value or the coefficient N of the illumination frequency to a low value according to the calculation result of the density of the projected video.

[0065] <6-3> Effects of the Sixth Embodiment As described above, the zoetrope system 1E according to the sixth embodiment changes at least one of the dripping frequency and the illumination frequency according to the content of the video data while maintaining the relationship described in the first embodiment. In this way, the zoetrope system 1E according to the sixth embodiment can dynamically control the dripping frequency and the illumination frequency in accordance with the projection content. As a result, the zoetrope system 1E according to the sixth embodiment allows the user to view the water droplets WD under conditions more suitable for the projection content.

[0066] <7> Others As long as the operations described in the above embodiments can be realized, the water droplet generation device 10 and the projector 20 may each be externally connected. For example, the zoetrope system 1 may have at least a configuration capable of controlling the irradiation timing of the projection light PL of the projector 20 and a configuration capable of controlling the drip frequency and illumination frequency. The CPU 41 of the control device 40 may be another circuit. For example, the control device 40 may include an MPU (microprocessing unit) instead of a CPU. Each of the processes described in each embodiment may be realized by dedicated hardware. Each of the processes described in the above embodiments may be a mixture of processes executed by software and processes executed by hardware, or may be only one of them. The shutter 30 described in the first embodiment and the light source control unit 201 described in the second embodiment are configured to realize similar functions and may be referred to as a "control unit."

[0067] The present invention is not limited to the above-described embodiments, and various modifications can be made in the implementation stage without departing from the spirit of the invention. Furthermore, the embodiments may be implemented in appropriate combinations, in which case the combined effects can be obtained. Furthermore, the above-described embodiments include various inventions, and various inventions can be extracted by combining selected elements from the disclosed elements. For example, if the problem can be solved and the desired effect can be obtained even if some elements are deleted from all elements shown in the embodiments, the configuration from which these elements are deleted can be extracted as an invention.

[0068] 1, 1A, 1B, 1C, 1D, 1E... Zoetrope system 10, 10A... Water droplet generation device 11... Water storage tank 12... Pump 13, 13-1 to 13-4... Nozzle 14... Vibrator 20, 20A... Projector 21... Light source 22... Illumination optical system 23... Liquid crystal panel 24... Projection lens 30... Shutter 40, 40A, 40B, 40C, 40D, 40E... Control device 41... CPU 42... ROM 43... RAM 44... Communication module 45... Storage device 201... Light source control unit 202... Projection unit 401, 401A... Drop timing control unit 402, 402A, 402B, 402C... Illumination timing control unit 403, 403A, 403B... Projection image control unit 404... Image storage unit 405... Image analysis unit 406... Frequency control unit CR1 to CR4... Row range VR, VR1, VR2... Visible range PL, PL1, PL2... Projection light PU, PU1, PU2... Projection unit

Claims

1. A zoetrope system that utilizes a water droplet generation device that drips liquid and a projector that projects light to display an image, comprising: a control unit configured to control whether or not the projection light of the projector is irradiated onto an area onto which liquid is dripped by the water droplet generation device; and a processor configured to set a first frequency at which the water droplet generation device drips liquid and a second frequency at which the control unit irradiates the projection light onto said area, wherein the processor sets the second frequency to an integer multiple of the first frequency.

2. The zoetrope system of claim 1, wherein the refresh rate of the projector is 240 Hz or less, and the time that the control unit irradiates the projection light onto the range in one cycle of the second frequency is 2 milliseconds or less.

3. The zoetrope system of claim 1, wherein the control unit is a liquid crystal shutter or a rotating body with slits arranged between the range and the projector, and is configured to control the transmission and blocking of the projection light according to the second frequency.

4. The zoetrope system of claim 1, wherein the control unit is configured to control the on / off of a light source used by the projector to generate the projection light in accordance with the second frequency.

5. The zoetrope system of claim 1, further comprising a plurality of projection units each including the projector and the control unit, the plurality of projection units being arranged in approximately the same position, and the processor being further configured to set the second frequency to the projector of each of the plurality of projection units with a phase difference.

6. The zoetrope system of claim 1, further comprising a plurality of projection units each including the projector and the control unit, the plurality of projection units being spaced apart, and the processor being further configured to synchronize the timing at which the projector of each of the plurality of projection units irradiates the projection light onto the range.

7. The zoetrope system of claim 1, wherein the droplet generating device has a plurality of nozzles, each configured to drip liquid, arranged parallel to the projection surface of the projection light and in a direction intersecting the direction in which the liquid is dripped, and the projector is positioned so that it can irradiate the projection light onto a plurality of row ranges into which liquid is respectively dripped by the plurality of nozzles.

8. The zoetrope system of claim 1, wherein the processor is further configured to change at least one of the first frequency and the second frequency depending on the analysis results of the image projected by the projector.

Images