JP6758090B2 - Image projection system - Google Patents

Description

The present invention relates to an image projection system composed of a plurality of image projection devices.

In recent years, for example, a raster scan method in which a semiconductor light source such as an LED or a semiconductor laser is combined with a small optical deflector such as a MEMS (Micro Electro Mechanical Systems), a DMD (Digital Mirror Device), or an LCOS (Liquid Crystal On Silicon). Image projection devices have been developed for pico projectors and head-up displays.

The DMD and LCOS have a feature that only necessary pixels are selectively switched from a light source that covers the entire projection screen, and light that is not used for projection is absorbed by a filter or an absorber. On the other hand, MEMS is excellent in light utilization efficiency because the light source is turned on only in a necessary part of the projection screen in response to two-dimensional scanning.

In addition, a system that forms one image using multiple image projection devices has also been developed, and various effects can be produced as a replacement for the conventional multi-monitor display system or as projection mapping using the outer wall of a building as a screen. Is used for. As a projection method using a plurality of image projection devices, a method of partially changing the resolution of an image by superimposing and projecting a plurality of projected images is known.

For example, Patent Document 1 employs a projection method in which an image superimposing portion is created by using two projectors, a projector for whole projection and a projector for local projection, and the resolution can be partially changed (paragraph 0005, Figure 1).

Japanese Unexamined Patent Publication No. 2004-070257

However, a composite image generated by a plurality of projectors (image projection devices) as in the projection method of Patent Document 1 has the brightest central portion and tends to gradually darken toward the periphery. In such an image pattern, the human line of sight naturally gathers in the central part, and when multiple projectors are operating at the same frame rate, due to the characteristics of human vision, the peripheral part rather than the central part of the image. The flicker is noticeable.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an image projection system capable of controlling a plurality of image projection devices to generate a composite image with suppressed flicker. To do.

The image projection system of the present invention uses a raster scan method to obtain a plurality of image projection devices that project sub-images having different projection ranges, and a brightness distribution of the image projection range given to each image projection device from the brightness distribution of the input image. A video signal distribution unit that extracts and outputs an individual video signal representing the brightness distribution of the extracted image projection range to each image projection device and a frame rate when each image projection device projects the sub image are determined. The video signal distribution unit includes a frame rate changing unit, and the video signal distribution unit projects a sub image of the first image projection range having the lowest maximum brightness and the widest projection angle range among the plurality of image projection devices. A first individual video signal is output to the first video projection device, and a sub video of another video projection range different from the first video projection range is projected to the other video projection device. Another individual video signal is output to, and the frame rate changing unit sets the frame rate of the first video projection range to the fastest among the frame rates of all the video projection ranges, and the first video projection A composite image is generated by superimposing the sub image projected from the device and the sub image projected from the other image projection device, and the first image projection range constituting the composite image is set in advance. The image projection device for projecting the first image projection range is provided with a responsible projection range switching unit for switching from the plurality of image projection devices according to predetermined conditions .

Image projection system of the present invention, Ru projection range is composed of a plurality of image projection apparatus for projecting a different sub-images. The first individual video signal from the first video projection device has the widest projection angle range, but the lowest maximum brightness, and the frame rate changer sets the frame rate of the first individual video signal to any other. Set faster than individual video signals. Then, one composite video is generated by combining the sub video by the first individual video signal and the sub video by the individual video signal from another video projection device. This makes it possible to generate a natural composite image with suppressed flicker.

In an image projection device that is in charge of a relatively wide projection range, the deflection angle of the mirror portion is always large, so that the load on the device is large. According to this configuration, the responsible projection range switching unit switches the image projection device that projects the first image projection range from among a plurality of image projection devices according to predetermined conditions, so that the load of each image projection device is distributed. Will be done. As a result, the product life (usable period) can be extended.

Further, in the present invention, it is preferable that the synthetic image includes a non-projection region where light is not projected .

According to the present invention, by providing a non-projection region in the composite image, it can be used as a mask portion for preventing dazzling of the driver of an oncoming vehicle when the image projection system is used as a vehicle lighting system.

The schematic diagram of the image projection system of 1st Embodiment. The schematic diagram of the image projection apparatus of the image projection system of 1st Embodiment. The explanatory view of the image signal processing part of the image projection apparatus of 1st Embodiment. The perspective view of the MEMS used for the image projection apparatus of 1st Embodiment. The figure which shows the relationship between the semiconductor light source, the MEMS mirror, and the image projection range (image projection range) projected from the image projection apparatus. The figure which shows the waveform change of the drive signal of the MEMS mirror and the semiconductor light source which swings in the sub-scanning direction with the passage of time. The figure which shows the waveform change of the drive signal of the MEMS mirror and the semiconductor light source which swings in the main scanning direction with the passage of time. 6A and 6B are diagrams showing the relationship between the drawing range of the projected image based on the drive signals of the MEMS mirror and the semiconductor light source and the scanning locus. The figure which shows the relationship between the projection angle range of each image projection apparatus and the maximum brightness. The figure which shows the relationship between the luminance distribution of an input image, and the image projection range of the 1st image projection apparatus to the 4th image projection apparatus. A cross-sectional view of the luminance distribution with respect to the reference line added to the input image of FIG. 9A. The figure which shows the image projection range of the image projection system of 2nd Embodiment. The figure explaining the switching of the image projection range of the 1st image projection apparatus to the 4th image projection apparatus.

[First Embodiment]
As shown in FIG. 1, in the image projection system 1 of the present embodiment, a plurality of image projection devices 10A to 10D (hereinafter, may be referred to as an image projection device 10) and an image signal representing an input image are input. A video signal distribution unit 20 that outputs an individual video signal representing the brightness distribution of the video projection range and an offset signal described later to the video projection devices 10A to 10D is provided. Hereinafter, the image projection system of the present embodiment will be described using an image projection system including four image projection devices, but the number of devices is not limited to four and may be two or more.

First, the video signal distribution unit 20 of the present embodiment (corresponding to the “synthetic video generation unit” and the “in charge projection range switching unit” of the present invention) includes a CPU, ROM, RAM, an I / O circuit, and an A / D. The brightness distribution of the image projection range given to each image projection device 10 is extracted from the brightness distribution of the input image represented by the image signal obtained from the image source, which is composed of an electronic circuit such as a circuit (not shown). Then, the video signal distribution unit 20 outputs an individual video signal representing the brightness distribution of the extracted video projection range to each video projection device 10.

Further, the video signal distribution unit 20 identifies the position of the highest luminance point in the brightness distribution of the input video, and sets an offset signal at which the center of the video projection range of each video projection device 10 can be set at the position of the highest luminance point for individual video. It is output to each image projection device 10 together with the signal.

The offset signal is to offset (position) the image projection range to a desired range of the drawing range with respect to the image projection device having the image projection possible range due to the limitation of the deflection angle of the MEMS mirror 106 described later. It is a signal. Specifically, the offset signal is a signal indicating the amount of displacement to be moved in the horizontal and vertical directions from the reference position with the center of the entire screen on which the image is projected as the reference position.

Each image projection device 10 can move the image projected by each image projection device 10 in the vertical and horizontal directions according to the offset signal. The movement of the projected image in the vertical and horizontal directions is carried out by providing a stepping motor or the like in each image projection device 10.

As shown in FIG. 2, the image projection device 10 of the present embodiment includes a MEMS mirror 106, a semiconductor light source 112, a MEMS mirror 106, and a control unit 30 that outputs a signal to the semiconductor light source 112, and is a raster scan described later. It is a device that performs.

The control unit 30 of the image projection device 10 is an individual image signal input unit 102 into which an individual image signal generated based on an image signal output from an image source such as a personal computer or a camera system is input, and an individual image received. An individual video signal storage unit 104 that writes / reads each predetermined bit to process a signal, a MEMS drive unit 108 that outputs an AC wave drive signal to the MEMS mirror 106, and a MEMS drive unit according to the drive signal. When the mirror 106 rotates around the rotation axis, the sensor signal input unit 110 into which a signal from a sensor that outputs a voltage corresponding to the deflection angle of the MEMS mirror 106 is input, and an LED that irradiates the MEMS mirror 106 with light. It is composed of a light source driving unit 114 that outputs pixel data to a semiconductor light source 112 such as a semiconductor laser or a semiconductor laser, and an individual video signal processing unit 116 that processes individual video signals to control the image projection device 10.

In the present embodiment, for convenience of explanation, a sine wave-shaped drive signal will be used as the AC wave drive signal for driving the MEMS mirror 106, but the phase will be delayed by 90 ° with respect to the sine wave-shaped drive signal. A sine wave-shaped signal or the like may be used.

The individual video signal input unit 102 outputs the input individual video signal to the individual video signal processing unit 116 in order to process the video signal. As the individual video signal input unit 102, a video signal receiver such as VGA (analog RGB), DVI, HDMI (registered trademark), or DisplayPort can be used.

The individual video signal storage unit 104 writes / reads a signal in order to process the individual video signal output from the individual video signal input unit 102. As the individual video signal storage unit 104, SDRAM or the like can be used. In the image projection system of the present embodiment, since the image signal is generated as a high-speed signal, DDR2- SDRAM and DDR3-SDRAM are suitable.

The MEMS drive unit 108 is a D / A converter that converts a digital signal from the individual video signal processing unit 116 into an analog signal in order to output a drive signal to the MEMS mirror 106, and the output signal is a drive voltage of the MEMS mirror 106. It consists of an operational amplifier that amplifies to a level.

The sensor signal input unit 110 is a signal from the sensor that outputs a voltage corresponding to the deflection angle of the MEMS mirror 106 when the MEMS mirror 106 rotates around the rotation axis in response to the drive signal and swings in the scanning direction. Is the signal input unit to which is input. The sensor signal input unit 110 includes an A / D converter that converts the received analog signal into a digital signal output to the individual video signal processing unit 116, and an operational amplifier that secures an appropriate input level for the A / D converter. To.

The light source drive unit 114 is composed of a high-speed D / A converter that converts a digital signal output from the individual video signal processing unit 116 into an analog signal, a driver transistor having a current capacity that can drive the semiconductor light source 112 of each RGB color, and the like. It is composed.

The individual video signal processing unit 116 processes the individual video signal and controls the image projection device 10. The individual video signal processing unit 116 can use, for example, an FPGA (Field-Programmable Gate Array), a microprocessor, or a hybrid device (EPP (Extensible Processing Platform) or SoC (System on Chip)) thereof.

Further, as shown in FIG. 3, the individual video signal processing unit 116 includes an input video processing unit 120 as an interface for outputting the individual video signal from the individual video signal input unit 102 to the individual video signal storage unit 104, and the individual video. Based on the signal output from the signal storage unit 104, the drive signal is generated to generate the drive signal of the MEMS mirror 106 to be sent to the MEMS drive unit 108 and the signal to be the basis of pixel data extraction to be sent to the light source drive unit 114. Resonance frequency tracking control is performed based on the signals output from the unit 122 (corresponding to the "frame rate changing unit" of the present invention), the sensor signal input unit 110, and the drive signal generation unit 122, and the pixel data extraction unit 126 The pixel data extraction unit that extracts the pixel data to be transmitted to the light source drive unit 114 based on the signals output from the drive signal calculation processing unit 124, the drive signal generation unit 122, and the drive signal calculation processing unit 124. It is composed of 126 and a comprehensive control unit 128 that controls the control parameters of each of these signal processes and also functions as an interface with an external control means (not shown) such as a switch and a UART (Universal Asynchronous Receiver Transmitter). ..

Further, as shown in FIG. 4, the MEMS 130 including the MEMS mirror 106 of the present embodiment has a first support portion 132 in which the MEMS mirror 106 having a reflecting surface is supported by a pair of torsion bars 131A and 131B, and a MEMS mirror 106. The pair of torsion bars 131A and 131B with respect to the first support portion 132, that is, the first actuators 134 and 136 that swing in the main scanning direction (around the Y axis) and the second support portion 132 that supports the first support portion 132. Two axes capable of two-dimensional scanning provided with a support portion 138 and second actuators 140 and 142 that swing the first support portion 132 with respect to the second support portion 138 in the sub-scanning direction (around the X-axis). It is a type light deflector.

In the image projection device 10 provided with the MEMS 130, the semiconductor light source 112 is turned on so that light is projected only in the drawing range in the image projection range described later in accordance with the two-dimensional scanning, so that the light utilization efficiency can be improved. Can be planned.

As the actuator of the MEMS 130, a piezoelectric type, an electrostatic type, or an electromagnetic type actuator can be used. In this embodiment, piezoelectric actuators are used as actuators 134 and 136. Further, the actuators 140 and 142 are configured by connecting four piezoelectric cantilever levers, respectively. Each of the piezoelectric cantilever levers 140A to 140D and 142A to 142D includes a laminate composed of a support, a lower electrode, a piezoelectric body, and an upper electrode.

The projection of the image based on the image signal is executed by high-speed scanning in the horizontal direction and low-speed scanning in the vertical direction. Therefore, the MEMS mirror 106 swings in the main scanning direction by the resonance drive of the actuators 134 and 136 corresponding to the high-speed operation, and swings in the sub-scanning direction by the non-resonant drive of the actuators 140 and 142 corresponding to the low-speed operation.

In the present embodiment, since the swing in the sub-scanning direction is a low-speed operation, the non-resonant drive actuators 140 and 142 are used, but the present invention is not limited to this, and a resonance drive actuator may be used.

In order to detect the rotational state of the MEMS mirror 106, the first support portion 132 is provided with sensors 144A and 144B at positions adjacent to the torsion bars 131A and 131B, and sensors 146 near the actuators 140 and 142. Has been done. As the position sensor, a sensor using the piezoelectric effect or a sensor using the piezoresistive effect can be adopted. The sensor using the piezoelectric effect operates as a velocity sensor that returns a differential value with respect to the displacement amount of the deflection angle of the MEMS mirror 106. Further, the sensor using the piezoresistive effect operates as a position sensor that returns a value proportional to the displacement amount of the deflection angle of the MEMS mirror 106.

It is preferable to use the actuator and the sensor using the piezoelectric effect in that the laminated structure of the actuator and the sensor can be formed by the same manufacturing process.

Further, at least one of the sensors 144 and 146 needs to be provided, respectively, but in order to improve the swing stability in the main scanning direction and the sub scanning direction of the MEMS mirror 106 and the noise canceling effect of the differential signal, the figure shows. As shown in 4, it is preferable to provide two lines symmetrically about the Y-axis and the X-axis.

Next, a raster scan mainly using the semiconductor light source 112 and the MEMS mirror 106 of the MEMS 130 will be described with reference to FIGS. 5 to 7.

As shown in FIG. 5, the light incident on the MEMS mirror 106 from the semiconductor light source 112 and reflected reflects an image (scanning locus) in the image projection range. With respect to drawing an image, the MEMS mirror 106 swinging in the sub-scanning direction executes a vertical scan in the image projection range of FIG. The waveform of the drive signal of the MEMS mirror 106 swinging in the sub-scanning direction of the present embodiment preferably has a sawtooth shape shown in FIG. 6A.

Since the MEMS mirror 106 swinging in the sub-scanning direction is driven at a low speed, either a resonant drive actuator or a non-resonant drive actuator can be used, but a sawtooth-shaped drive signal suitable for the non-resonant drive actuator can be used. By securing a long effective drawing time by using the above, the brightness of the projected screen can be improved.

Specifically, in the sawtooth-shaped drive signal, sections in which the slope of the waveform of the drive signal is gentle with respect to the passage of time and sections in which the slope is steep appear alternately (see FIG. 6A). Then, the semiconductor light source 112 is turned on and drawn in a section where the sawtooth-shaped drive signal has a gentle slope (drawing interval), and the semiconductor light source 112 is turned off in a section where the slope is steep (vertical blanking interval). ) Is provided.

In the vicinity of the apex where the slope of the sawtooth-shaped drive signal changes, the MEMS mirror 106 swinging in the sub-scanning direction is in a very low-speed drive state, so that the drawing portion corresponding to the section near the apex is the drawing range. It looks particularly bright when compared to other parts. Therefore, in the section near the apex, the uniformity of the brightness of the entire screen represented by the drawing range can be realized by turning off the semiconductor light source 112.

On the other hand, the MEMS mirror 106 swinging in the main scanning direction performs horizontal scanning in the image projection range of FIG. The waveform of the drive signal of the MEMS mirror 106 swinging in the main scanning direction of the present embodiment is preferably an AC wave shown in FIG. 6B, for example, a sine wave shape. Since the MEMS mirror 106 swinging in the main scanning direction is driven at high speed, it is preferable to use a resonance drive actuator, and it is preferable to use a sinusoidal drive signal suitable for the resonance drive actuator. ..

Specifically, in the sinusoidal drive signal, sections near the apex of the waveform of the drive signal with respect to the passage of time and sections other than the apex appear alternately (see FIG. 6B). Therefore, as shown in FIG. 5, it is preferable to perform drawing by reciprocating scanning, that is, both rightward scanning and leftward scanning, from the viewpoint of ensuring an effective drawing time. Reciprocating scanning, that is, compared to a method in which drawing is performed only by one-sided scanning, for example, rightward scanning (leftward scanning), and a non-drawing section (horizontal return section) is provided in leftward scanning (rightward scanning). , Drawing can be performed by both right-hand scanning and left-hand scanning, and a long effective drawing time can be secured.

Further, in the vicinity of the apex of the sinusoidal drive signal (horizontal folding section), the MEMS mirror 106 swinging in the main scanning direction is in a very low speed driving state, so that the drawing portion corresponding to the section near the apex is It looks particularly bright when compared to other parts of the drawing range. In order to realize the uniformity of the brightness of the entire screen represented by the drawing range, as shown in FIG. 6B, in the section between the sections near the apex adjacent to the elapsed time (horizontal folding section). The semiconductor light source 112 is turned on to draw one line of the scanning locus in the horizontal direction of FIG. 5, and the semiconductor light source 112 is turned off in the horizontal folding section to provide a non-drawing section.

By performing the above-mentioned raster scan, as shown in FIG. 7, the drawing range in which the peripheral region of the image projection range of FIG. 5 is cut out in the horizontal and vertical directions from the entire scanning locus on the scanned surface is obtained. can get.

Next, the video produced by the distribution processing by the video signal distribution unit 20 will be described. In the distribution processing of the video signal distribution unit 20, a video signal having a distribution in which the brightness in the horizontal direction and the brightness in the vertical direction decrease monotonically is processed centering on the highest luminance point existing on the screen.

FIG. 8 shows the projection angle range (the range in which the image can be projected) represented by the horizontal and vertical deflection angles of the MEMS mirror 106 by the image projection devices 10A to 10D of the image projection system 1 of the present embodiment. It is a figure which illustrated the relationship with the maximum brightness expressed by the brightness.

As shown in FIG. 8, in the present embodiment, the projection angle range and the maximum brightness of the image projection devices 10A to 10D are the ranges in which the image can be projected in the order of the image projection devices having the largest maximum brightness, which is the upper limit of the relative brightness. The projection angle range is set to be narrow. The pixel pitches of the image projection devices 10A to 10D are set to be the same from the viewpoint of ease of control, but the pixel pitch is not limited to this, and the pixel pitches of the image projection devices 10A to 10D are set to different values. May be good. When the pixel pitches of the image projection devices 10A to 10D are set to different values, the image projection devices 10A to 10D perform resolution scaling.

Next, FIG. 9A shows the result of performing a series of distribution processing by the video signal distribution unit 20. The image projection device 10A is in charge of projecting a first image projection range having the lowest maximum brightness and the widest projection angle range. Further, the image projection devices 10B, 10C, and 10D are in charge of projecting the second, third, and fourth image projection ranges, respectively. Then, the images (sub-images) of the luminance distribution represented by the individual image signals output to the image projection devices 10A to 10D are combined to create the final image (composite image).

As shown in FIG. 9A, the image projected from the image projection devices 10A to 10D has a luminance distribution in which the central portion is the brightest (highest luminance point) and gradually becomes darker toward the peripheral portion. The brightness distribution does not necessarily have to be symmetrical in the vertical and horizontal directions, and there may be a partial non-projection range (mask portion).

It should be noted that each projection range does not have to be exclusive, but rather by positively superimposing the images, even if vibration is applied to any of the image projection devices 10A to 10D from the outside, the seams of the images due to distribution are obtained. Has the advantage of being less noticeable.

The frame rate (the number of frames processed per unit time) is such that the first image projection range with the widest projection range is the fastest, and the frame rate decreases in the order of the second, third, and fourth image projection ranges. Set. For example, the frame rate of the first image projection range is 240 Hz, and the frame rates of the second, third, and fourth image projection ranges are 180 Hz, 120 Hz, and 60 Hz, respectively. This makes it possible to prevent the peripheral portion of the composite image from flickering.

Here, it is not preferable to set the frame rate of the image projection devices 10A to 10D uniformly high. This is because the image projection device in charge of the projection range having a narrow image projection range and high maximum brightness is driven by a large current, and the drive waveform becomes dull and the projected image deteriorates.

In FIG. 9B, the one-dot chain line, the two-dot chain line, the broken line, and the solid line are individual images output to the fourth image projection device 10D, the third image projection device 10C, the second image projection device 10B, and the first image projection device 10A, respectively. The range of the luminance distribution corresponding to the signal is shown.

In the distribution process of the video signal distribution unit 20, the image projection devices 10A to 10C other than the fourth image projection device 10D, which has the maximum relative brightness upper limit among the image projection devices 10A to 10D, have their respective upper limits of relative brightness. As the value, the maximum value of the relative brightness of each of the image projection devices 10A to 10C is used. That is, the maximum brightness 256, 512, 1024, and 2048 are set as upper limit values for the image projection devices 10A, 10B, 10C, and 10D.

[Second Embodiment]
Next, the image projection system 1'of the second embodiment will be described with reference to FIGS. 10A and 10B.

In the image projection system 1'of the present embodiment, the image projection range in charge of the image projection devices 10A to 10D can be switched at a predetermined timing. The internal configurations of the image projection devices 10A to 10D and the image signal distribution unit 20 are the same as those of the image projection system 1.

First, the first image projection device 10A is in charge of projecting an image projection range a (see FIG. 10A) having the lowest maximum brightness and the widest projection angle range. Further, the second image projection device 10B is in charge of projection of the image projection range b, the third image projection device 10C is in charge of projection of the image projection range c, and the fourth image projection device 10D has the highest maximum brightness and the highest projection angle range. It is in charge of projecting a narrow image projection range d (“state 1” in FIG. 10B).

Here, the image projection device 10A in charge of the image projection range a having the widest projection area is in a state where the load on the device is also large because the deflection angle of the MEMS mirror 106 is always large. Therefore, for example, the image projection range is switched at the timing when the image projection is interrupted. Specifically, the state of the image projection devices 10A to 10D is stored in the RAM of the video signal distribution unit 20, and the state information is read out when the projection is restarted, and the image projection devices 10A to 10D are stored in the previous state. Assign a different image projection range than the person in charge of.

As shown in FIG. 10B, four types of "state 1" to "state 4" are defined, and the states are switched at the timing when the image projection of the image projection devices 10A to 10D is interrupted. When shifting to "state 2" after "state 1", the first image projection device 10A switches from the image projection range a to the image projection range b, and the second to fourth image projection devices also project images in a predetermined order. The range switches. It is preferable to switch between "state 1" and "state 4" in the same period. As a result, in the image projection system 1', the load applied to the image projection devices 10A to 10D can be dispersed and the product life (usable period) can be extended.

The above embodiment is an example of the present invention, and various other modifications are conceivable. Since the image projection system 1 (1') was composed of four image projection devices, the image projection range was also four, but it is composed of two or more image projection devices, and the image projection according to the number thereof. Any image projection system with a range may be used.

The wider the image projection range, the higher the frame rate, but it does not necessarily have to match the number of image projection ranges. For example, although there are four image projection ranges in FIG. 10A, the frame rates of the image projection range c and the image projection range d may be shared to provide a total of three types of frame rates.

1,1'... image projection system, 10,10A, 10B, 10C, 10D ... image projection device, 20 ... image signal distribution unit (synthetic image generation unit), 30 ... control unit, 103 ... spectroscope, 105 ... fixed mirror , 106 ... MEMS mirror, 112 ... semiconductor light source, 130 ... MEMS (optical deflector), 134, 136 ... actuator, 144, 144A, 144B, 146 ... sensor.

Claims (2)

Multiple image projection devices that project sub-images with different projection ranges by the raster scan method,
With a video signal distribution unit that extracts the brightness distribution of the video projection range given to each video projection device from the brightness distribution of the input video and outputs an individual video signal representing the extracted brightness distribution of the video projection range to each video projection device. ,
Each image projection device includes a frame rate changing unit that determines a frame rate when projecting the sub image.
The video signal distribution unit refers to a first video projection device that projects a sub-image of the first video projection range having the lowest maximum brightness and the widest projection angle range among the plurality of video projection devices. The first individual video signal is output, and the other individual video signal is output so as to project a sub-video of another video projection range different from the first video projection range to the other video projection device. ,
The frame rate changing unit sets the frame rate of the first image projection range to the fastest among the frame rates of all the image projection ranges.
A composite image is generated by superimposing the sub image projected from the first image projection device and the sub image projected from the other image projection device.
The first image projection range constituting the composite image is preset.
An image projection system comprising a responsible projection range switching unit that switches an image projection device that projects the first image projection range from among the plurality of image projection devices according to predetermined conditions . In the image projection system according to claim 1,
The composite image is an image projection system characterized in that it includes a non-projection region in which light is not projected.