JP2015061241A - Projection system, optical path switching device, and projection control method - Google Patents

Abstract

Projection onto a plurality of screens is performed with a simple system configuration. A projection system (1) projects a projection system (11 to 16) for projecting an image, and a CPU (Synchronization signal output unit (communication unit) SO) outputs a synchronization signal for switching image projection by the projection system to time division. 20) and a dimming structure that emits incident light in either the first direction or a second direction different from the first direction, and a synchronization signal from the projection apparatus 10 And a light path switching device 50 for switching and emitting the incident light in the first direction or the second direction in a time-division manner by the dimming structure. [Selection] Figure 1

Description

  The present invention relates to a projection system, an optical path switching device, and a projection control method for realizing various video expressions.

  2. Description of the Related Art Conventionally, there has been proposed a technique for realizing a projection display system that can be easily installed even in a narrow space with a wide projection angle of view and can display a good large screen image without distortion. (For example, Patent Document 1)

JP 2009-288803 A

  In the technique described in the above-mentioned patent document, a projection screen display device and a screen are paired, and a plurality of sets are arranged in the same plane or a U-shape to realize display on a multi-screen screen. .

  However, when images are projected on a plurality of screens, a projection display apparatus is required by the number of the screens. In addition, when realizing display on a multi-screen screen using a plurality of projection type video display devices, it is necessary to synchronize images projected on each display device. There was also a problem that it was not easy to realize.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a projection system, an optical path switching device, and a projection control capable of expressing various images using a plurality of screens with a simple system configuration. It is to provide a method.

  According to one embodiment of the present invention, a projection apparatus having a projection unit that projects an image, and incident light from a projection unit of the projection apparatus in either a first direction or a second direction different from the first direction And a light path switching device including switching control means for controlling the emission direction to be switched in a time-sharing manner by the light control structure.

  According to the present invention, various video expressions using a plurality of screens are possible with a simple system configuration.

The figure which shows the use environment of the projection system which concerns on one Embodiment of this invention. FIG. 2 is a block diagram showing a schematic functional configuration of the projection apparatus according to the embodiment. The figure which shows the relationship between the waveform of a synchronizing signal supplied to the optical path switching apparatus from the projector which concerns on the same embodiment, and operation | movement. 6 is a flowchart showing the contents of main image determination processing according to the embodiment. The figure which shows the example of the multiscreen projection which concerns on the same embodiment. The figure which shows the use environment of the projection system which concerns on another embodiment of this invention.

  Hereinafter, an embodiment in which the present invention is applied to a projection system including a DLP (Digital Light Processing) (registered trademark) type projection apparatus will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating a use environment of a projection system 1 according to the present invention. In the figure, reference numeral 10 denotes a projection device, and an image emitted from the projection device 10 is transmitted or reflected through the optical path switching device 50, and is time-divided into both the first screen SC1 and the second screen SC2. (The details will be described later).

  The optical path switching device 50 can electrically switch between transmission and reflection with respect to incident light in an extremely short period by a dimming structure described later. The optical path switching device 50 is connected to the projection device 10 via a USB cable UC, and is transmitted and reflected, for example, every 1/120 second by a synchronization signal (switching signal) given from the projection device 10 via the USB cable UC. By repeating the above, it becomes possible to project an image as if it were simultaneously projected onto both the first screen SC1 and the second screen SC2 by the afterimage effect with the naked eye.

  As described above, the time division here refers to switching in a time period in which an afterimage (phenomenon) with the naked eye can be used like a field (frame) sequential 3D image display system.

  When performing projection in the positional relationship as shown in FIG. 1, the person WC projects the image projected on the first screen SC1 serving as the front projection and the second screen SC2 serving as the rear projection positioned in front of the image. You can watch the image projected on the screen at the same time.

As the dimming structure constituting the optical path switching device 50, for example, one using a switching diffraction grating or one using a polarization conversion element can be considered.
In the method using the switching diffraction grating, the transmission path is electrically switched (bending the optical path), for example, sold under the trade name “DigiLens (registered trademark)” (http://www.abglabs.com/). By using the element and reflecting the light transmitted through one optical path by the total reflection mirror, it is possible to electrically switch between transmission and reflection of incident light as a whole.

  In the method using a polarization conversion element, for example, the electrical polarization direction (P phase and the phase switch) (sold under the trade name “http://www.colorlink.co.jp/products/index.html”) is used. (S phase) is used, a reflection side polarizing plate is combined on the exit side of the element, and a polarizing beam splitter is arranged at the rear stage of the projection lens of the projection device 10 so that only a specific polarization direction is obtained. By transmitting / reflecting the light, it is possible to electrically switch between transmission and reflection of incident light as a whole by aligning the polarization direction of the light incident on the optical path switching device 50.

  Next, with reference to FIG. 2, the functional configuration of mainly the electronic circuit of the projection apparatus 10 according to the present embodiment will be described. In the figure, the image data input to the input processing unit IP is digitized by the input processing unit IP as necessary, and then sent to the image driving unit 11 via the system bus SB.

  The image driving unit 11 multiplies a frame rate according to a predetermined format, for example, 120 [frames / second], the number of color component divisions, and the number of display gradations according to the transmitted image data. The micromirror element 12 as a display element is driven to display by high-speed time-division driving.

  The micromirror element 12 performs a display operation by individually turning on / off each inclination angle of a plurality of micromirrors arranged in an array, for example, WXGA (horizontal 1280 pixels × vertical 768 pixels) at high speed. Then, an optical image is formed by the reflected light.

  On the other hand, R, G, B primary color lights are emitted cyclically from the light source unit 13 in a time division manner. The light source unit 13 includes an LED, which is a semiconductor light emitting element, and repeatedly emits R, G, and B primary color lights in a time-sharing manner. The LED included in the light source unit 13 may include an LD (semiconductor laser) or an organic EL element as an LED in a broad sense.

  Moreover, it is good also as what uses the primary color light from which a wavelength differs from the original light excited by irradiating the light radiate | emitted from LED to a fluorescent substance. The primary color light from the light source unit 13 is totally reflected by the mirror 14 and applied to the micromirror element 12.

  Then, an optical image is formed by the reflected light from the micromirror element 12, and the formed optical image is projected to the outside through the projection lens unit 15.

  The projection lens unit 15 includes a focus lens for moving a focus position and a zoom lens for changing a zoom (projection) angle of view in an internal lens optical system, each of which is a lens motor (M). The position along the optical axis direction is selectively driven by a gear mechanism 16 (not shown).

  Further, an optical lens 17 and a distance sensor 18 are provided in the vicinity of the projection lens unit 15. The distance sensor 18 includes a plurality of points, for example, rectangular corner portions, that are not less than three points that are not on a straight line in the projection range in a state where the projection zoom field angle of the projection lens unit 15 is minimized. Measure the distance up to 4 points. The output of the distance sensor 18 is digitized by the distance acquisition unit 19 and sent to the CPU 20 via the system bus SB.

  The CPU 20 controls all the operations of the above circuits. The CPU 20 is directly connected to the main memory 21 and the program memory 22. The main memory 21 is composed of, for example, an SRAM and functions as a work memory for the CPU 20. The program memory 22 is composed of an electrically rewritable nonvolatile memory such as a flash ROM, and stores an operation program executed by the CPU 20 and various fixed data.

  The CPU 20 reads out the operation program, fixed data, etc. stored in the program memory 22, develops and stores the program in the main memory 21, and executes the program, thereby controlling the projection apparatus 10 in an integrated manner. To do.

  The CPU 20 executes various projection operations in response to operation signals from the operation unit 23. The operation unit 23 receives key operation signals of some operation keys provided in the main body of the projection apparatus 10 or a key operation signal from a remote controller (not shown) dedicated to the projection apparatus 10 and responds to the received key operation signals. A signal is sent to the CPU 20.

  The operation keys received by the operation unit 23 include, for example, a power key for turning on / off the power of the projection apparatus 10, a zoom key +/− key, a focus +/− key, a volume +/− key, a menu key, a cross key, Screen selection for performing focus adjustment and keystone correction with priority given to one of the operation key related to the projection condition such as the enter key and the image projected onto the first screen SC1 and the image projected onto the second screen SC2. There is an operation key for.

The CPU 20 is further connected to the audio processing unit 24 and the synchronization signal output unit (communication unit) SO via the system bus SB.
The sound processing unit 24 includes a sound source circuit such as a PCM sound source, converts the sound signal given during the projection operation into an analog signal, drives the speaker unit 25 to emit sound, or generates a beep sound or the like as necessary.

  The synchronization signal output unit SO outputs a synchronization signal in units of image frames, which is given by the CPU 20 in synchronization with the driving of the micromirror element 12 in the image driving unit 11, for example, from the USB terminal via the USB cable UC. Output to the switching device 50.

Next, the operation of the above embodiment will be described.
FIG. 3 is a diagram showing the relationship between the waveform of the synchronization signal supplied from the projection device 10 to the optical path switching device 50 and the operation in the optical path switching device 50 associated therewith.

  As shown in FIGS. 3A and 3B, in the projection apparatus 10, the CPU 20 causes the image driving unit 11 to display an image for the first screen SC1 and an image for the second screen SC2. Two systems of images are alternately projected in units of one frame time (for example, 1/120 [second]).

  Along with this projection control, the CPU 20 causes the optical path switching device 50 to synchronize with the image for the first screen SC1 with the synchronization signal output unit SO as shown in FIG. In synchronization with the image for the second screen SC2, a synchronization signal that is at "L" level is output.

  Due to the synchronization signal given through the USB cable UC, the optical path switching device 50 projects the projection light emitted from the projection lens unit 15 when the synchronization signal is at “H” level as shown in FIG. Is transmitted and projected to the first screen SC1 side. On the other hand, when the synchronization signal is at the “L” level, the projection light emitted from the projection lens unit 15 is reflected and projected to the second screen SC2 side. The transmission / reflection operation is alternately executed.

  Therefore, if the image projected on the first screen SC1 and the image projected on the second screen SC2 in the projection device 10 are completely different contents that are not related to each other, Due to the afterimage effect of the WC with the naked eye, two different images can be simultaneously viewed on the first screen SC1 and the second screen SC2.

  Next, in the operation menu of the projection apparatus 10, one of the two systems of projection images is automatically determined as a main image and the other as a sub image, and the focus (focus) is adjusted to the projection environment on the main image side. ) An operation when executing main image determination processing for performing adjustment and / or keystone correction will be described.

  The operation described below is executed after the CPU 20 develops the operation program read from the program memory 22 in the main memory 21 as described above. The operation programs and the like stored in the program memory 22 are not limited to those stored in the program memory 22 at the time of factory shipment of the projection apparatus 10, but install a version upgrade program after the user purchases the projection apparatus 10. Including the contents.

  Note that the timing for performing the main image determination processing can be arbitrarily set by the setting operation from the operation menu when the power is turned on, when the image signal is initially input to the input processing unit IP, when the projection image is switched, or by the user of this system. It can be selected and set. Alternatively, it may be performed at a fixed time period such as 5 [minutes] or 10 [minutes]. However, when there is no switching of projection conditions and projection images, it is performed only once when the power is turned on. do it.

FIG. 4 shows the specific contents of the main image determination process, and waits for the timing to perform the main image determination process at the beginning (step S101).
When it is determined that it is time to perform the main image determination process, the optical path is switched by the distance sensor 18 in accordance with the image projection timing on the first screen SC1 at which the synchronization signal becomes “H” level. The distance to a total of four points that pass through the device 50 and become rectangular corners on the first screen SC1 is measured (step S102).

  Subsequently, the rectangular signal of the second screen SC2 is reflected by the distance sensor 18 reflecting the optical path switching device 50 in accordance with the timing of projecting the image onto the second screen SC2 at which the synchronization signal becomes “L” level. The distance to a total of four points to be a part is measured (step S103).

  After that, the CPU 20 performs orthogonal transformation on the image (first (system) image) to be projected at the image projection timing onto the first screen SC <b> 1 when the synchronization signal becomes “H” level, specifically, DCT (Discrete Cosine Transform) is executed to calculate a high frequency component in the video signal (step S104).

  Note that an image signal for projection input to the input processing unit IP is, for example, an MPEG (Moving Picture Experts Group) standard such as H.264. H.264 standard or AVCHD (Advanced Video Code High Definition) (registered trademark) standard data, etc., the above high-frequency component can be extracted in advance at the stage of decoding. Can be simplified.

  Further, in the same manner as described above, the CPU 20 performs orthogonal transformation on an image (second (system) image) to be projected at the image projection timing onto the second screen SC <b> 2 where the synchronization signal becomes “L” level next time. This is executed to calculate a high frequency component in the video signal (step S105).

  Subsequently, the CPU 20 compares the values of the high frequency components of the two images calculated in steps S104 and S105, and the high frequency component of the image on the first screen SC1 side is the high frequency component of the image on the second screen SC2 side. Depending on whether or not there are more images, the overall image tends to have more detailed contour patterns, more character images, high contrast, etc. It is determined whether or not there is (step S106).

  Here, when it is determined that the image projected on the first screen SC1 at which the synchronization signal is at the “H” level has more high frequency components, the first screen SC1 measured in the immediately preceding step S102. In order to prepare for the timing for performing (setting), storing (step S107) and performing the next main image determination process, conditions for executing the automatic focusing process and the keystone correction process according to the distance information of the four points up to Returning to the processing from step S101.

  In step S106, if it is determined that the image projected on the second screen SC2 in which the synchronization signal is at the “L” level has more high frequency components, the first measured in the previous step S103. The timing for obtaining (setting), storing (step S108) and performing the next main image determination process for obtaining the conditions for executing the automatic focusing process and the trapezoidal correction process in accordance with the distance information of the four points to the second screen SC2 In preparation for the above, the processing returns to step S101.

  FIG. 5 illustrates a state in which a white sand beach, the sea, and a horizontal line are projected on the first screen SC1, while a commercial image of sun oil is projected on the second screen SC2. Here, it is assumed that the person WC can appreciate the product image of the sun oil projected on the second screen SC2 with the image projected on the first screen SC1 as the background.

  When simultaneously projecting images from one projection apparatus 10 onto two screens SC1 and SC2 having different projection distances, at least one of the screens must be focused and become a blurred image.

  However, depending on the level of detail such as the contour pattern of the image, the content of the image is determined by estimating that the more detailed image is the main image and determining that one is the main image and the other is the sub-image. The focus can be adjusted to match

  When an image as shown in FIG. 5 is projected, a commercial image of sun oil is automatically determined as a main image, and an image of a white sand beach, the sea, and a horizontal line is automatically determined as a sub image.

  Then, at the time of actual synchronous switching projection, the respective trapezoid correction processing conditions are read based on the synchronization signal so that the trapezoid correction of the images projected on these two screens SC1 ′ and SC2 ′ is performed appropriately. To do.

  As a result, the images actually projected on both the screens SC1 ′ and SC2 ′ are both rectangular images having no trapezoidal distortion.

  Further, since it is difficult to switch at high speed for focusing at the time of actual synchronous switching projection, the focus adjustment conditions for the image determined to be the main image are read out regardless of the synchronization signal, and these two screens SC1 ′ are read out. , SC2 ′, the image determined as the main image is projected in a focused state.

  As a result, among the images that are actually projected simultaneously on the screens SC1 ′ and SC2 ′, an image that is determined to be a main image that is relatively required to be focused can be suitably projected in a focused state. it can.

  As described above in detail, according to the present embodiment, various video expressions using a plurality of screens can be realized with a simple system configuration.

  In the above embodiment, since the projection device 10 projects a plurality of images simultaneously on the first screen SC1 and the second screen SC2 in a time-sharing manner, more diverse and highly developable video expression is possible. It becomes.

  In this case, the main image can be estimated to be automatically determined according to the number of high-frequency components of the image to be projected, and the calculation of the high-frequency component itself also handles moving image data subjected to data compression. Since the device is relatively easy, it can be easily realized while reducing the burden on the CPU 20.

  In the above-described embodiment, the case where the optical path switching device 50 uses a switching diffraction grating, for example, as the dimming structure has been described. However, by using the switching diffraction grating, the number of parts is small and the configuration is high speed. An optical path switching device capable of split switching operation can be realized.

  Alternatively, when a polarizing beam splitter is used for the light control structure, an optical path switching device capable of high-speed time division switching operation can be realized.

  In the above embodiment, the case where an image is projected on the two screens of the first screen SC1 and the second screen SC2 from the projection device 10 via the optical path switching device 50 has been described. However, the present invention is not limited to this. Instead, by combining a plurality of light control structures in the optical path switching device 50, different images can be simultaneously projected onto three or more screens.

  In the above embodiment, the synchronization signal output unit (communication unit) SO is provided in the projection device 10 and the synchronization signal is output to the optical path switching device 50. However, the synchronization signal output unit SO (communication unit) is The optical path switching device 50 may be configured such that a synchronization signal is output to the projection device 10.

  In this case, the projection device 10 outputs an appropriate first (system) image and a second (system) image under appropriate conditions (conditions such as left-right inversion) according to the synchronization signal. You can do it.

  Further, as shown in FIG. 6, the system 1 ′ may be configured such that a switching control device 60 such as a PC for controlling both the projection device 10 and the optical path switching device 50 is separately provided.

  In the above embodiment, the communication between the devices has been described as an example in which the communication is performed by wire using the USB cable UC or the like. However, it goes without saying that the communication may be performed wirelessly.

  Further, the synchronization between the projection device 10 and the optical path switching device 50 may be performed by a method similar to that of the 3D projection system using the projection device and 3D liquid crystal glasses.

  Specifically, an IR method using infrared rays or a method (DLP-Link method) of controlling by superimposing a high-intensity pulse on the projection light itself for a very short time may be adopted.

  The former case can be realized by providing a transmission device and a reception device for a synchronization signal in each of the projection device 10 and the optical path switching device 50.

  In the latter case, a light receiving sensor is provided on the optical path switching device 50 side, thereby detecting a synchronization pulse superimposed on the projection light of the projection device 10 to realize synchronization control. In this case, it is not necessary to provide a special transmission device (transmission means) on the projection device 10 side, and the present invention can be easily realized at low cost.

  Furthermore, in the above-described embodiment, the example in which the main image and the sub-image are automatically determined has been described, but it is needless to say that the user may set and project them in advance.

  In FIG. 2, the optical lens 17, the distance sensor 18, and the distance acquisition unit 19 have been described as measuring the distance to the projection image. Instead, for example, an optical lens system and a solid-state imaging device such as a CCD, And a circuit configuration for measuring the distance from the drive position of the focus lens in the optical lens to the multiple positions of the projected image by a contrast-type automatic focusing process. It can also be considered.

  In addition, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention in the implementation stage. Further, the functions executed in the above-described embodiments may be combined as appropriate as possible. The above-described embodiment includes various stages, and various inventions can be extracted by an appropriate combination of a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, if the effect is obtained, a configuration from which the constituent requirements are deleted can be extracted as an invention.

Hereinafter, the invention described in the scope of claims of the present application will be appended.
According to a first aspect of the present invention, there is provided a projection apparatus having projection means for projecting an image, and incident light from a projection unit of the projection apparatus in a first direction or a second direction different from the first direction. A dimming structure that emits light on one side and an optical path switching device that includes switching control means for controlling the emission direction to be switched in a time-division manner by the dimming structure.

  According to a second aspect of the present invention, in the first aspect of the invention, the projection apparatus further includes a projection control unit configured to supply and project the images of a plurality of systems to the projection unit in a time division manner using the projection unit, The switching control unit controls the emission direction to be switched by the dimming structure in synchronization with time division timing of a plurality of images supplied to the projection unit by the projection control unit. To do.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the optical path switching device further includes a light receiving unit, and the projection device has a brightness higher than an image signal on an image projected by the projection unit. The switching control means detects the synchronization pulse by the light receiving means, and switches the emission direction by the dimming structure in synchronization with the time division timing of the image. It controls so that it may be displayed.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the projection device is switched by the optical path switching device, and the distance to the image projected in the first direction and the first. Distance acquisition means for acquiring a distance to an image projected in two directions, selection means for selecting one of the first direction and the second direction, a selection result in the selection means, and the distance acquisition means And a focus adjusting means for performing focus adjustment on the image projected by the projecting means based on the result obtained in the above.

  According to a fifth aspect of the present invention, in the invention of the fourth aspect, the projection apparatus further includes a detection unit that detects a high-frequency component amount of a spatial frequency for each of a plurality of images projected by the projection unit. The selection unit selects a direction corresponding to an image having a higher spatial frequency high-frequency component detected by the detection unit with respect to the images of the plurality of systems.

  According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, the projection device is switched by the optical path switching device up to a plurality of positions in the image projected in the first direction. Distance acquisition means for acquiring a distance to a plurality of positions in an image projected in the second direction, selection means for selecting one of the first direction and the second direction, and the selection Correction means for executing trapezoidal correction on the image projected by the projection means based on the selection result of the means and the acquisition result of the distance acquisition means.

  According to a seventh aspect of the present invention, in the invention according to any one of the first to sixth aspects, the dimming structure of the optical path switching device includes a switching diffraction grating.

  According to an eighth aspect of the present invention, in the invention according to any one of the first to sixth aspects, the dimming structure of the optical path switching device includes a polarization beam splitter.

  According to a ninth aspect of the present invention, there is provided an optical path switching device that cooperates with a projection device including a projection unit that projects an image, and projects a projection by switching a projection direction, and the incident light from the projection unit of the projection device is a first. Dimming structure that emits in one of the first direction and the second direction different from the first direction, and switching control means for controlling the switching of the emitting direction by the dimming structure in a time-sharing manner It is characterized by comprising.

  The invention described in claim 10 includes a projection device having a part for projecting an image, and a dimming structure that emits incident light in either the first direction or a second direction different from the first direction; A projection control method executed by a projection system comprising: a switching control step for controlling the emission direction of the light control structure to be switched in a time-sharing manner.

  DESCRIPTION OF SYMBOLS 1,1 '... Projection system, 10 ... Projection apparatus, 11 ... Image drive part, 12 ... Micromirror element, 13 ... Light source part, 14 ... Mirror, 15 ... Projection lens part, 16 ... Lens motor, 17 ... Optical lens, DESCRIPTION OF SYMBOLS 18 ... Distance sensor, 19 ... Distance acquisition part, 20 ... CPU, 21 ... Main memory, 22 ... Program memory, 23 ... Operation part, 24 ... Sound processing part, 25 ... Speaker part, 50 ... Optical path switching apparatus, 60 ... Switching Control device, IP ... input processing unit, SB ... system bus, SC1 ... first screen, SC2 ... second screen, SO ... synchronization signal output unit (communication unit), UC ... USB cable, WC ... person.

Claims (10)

A projection apparatus having projection means for projecting an image;
A dimming structure that emits incident light from the projection unit of the projection device in either the first direction or a second direction different from the first direction;
A projection system comprising: an optical path switching device including switching control means for controlling the switching of the emission direction by the light control structure in a time-sharing manner. The projection apparatus further includes a projection control unit configured to supply and project images of a plurality of systems to the projection unit in a time division manner by the projection unit,
The switching control unit controls the emission direction to be switched by the dimming structure in synchronization with time division timing of a plurality of images supplied to the projection unit by the projection control unit. The projection system according to claim 1. The optical path switching device further includes a light receiving means,
The projection device projects an image projected by the projection unit by superimposing a synchronization pulse having a luminance higher than that of the image signal,
The switching control means detects the synchronization pulse by the light receiving means, and controls the emission direction to be switched by the dimming structure in synchronization with the time division timing of the image. The projection system according to claim 1 or 2. The projection apparatus is
Distance acquisition means for acquiring a distance to the image projected in the first direction and a distance to the image projected in the second direction, which are switched by the optical path switching device;
Selecting means for selecting one of the first direction and the second direction;
2. A focus adjustment unit that performs focus adjustment on an image projected by the projection unit based on a selection result by the selection unit and an acquisition result by the distance acquisition unit. 3. The projection system according to any one of 3. The projection apparatus further includes a detection unit that detects a high-frequency component amount of a spatial frequency for each of a plurality of images projected by the projection unit,
5. The projection system according to claim 4, wherein the selection unit selects a direction corresponding to an image having a higher spatial frequency high-frequency component detected by the detection unit with respect to the images of the plurality of systems. The projection apparatus is
Distance acquisition for acquiring distances to a plurality of positions in the image projected in the first direction and distances to a plurality of positions in the image projected in the second direction, which are switched by the optical path switching device. Means,
Selecting means for selecting one of the first direction and the second direction;
6. A correction means for executing trapezoidal correction on an image projected by the projection means based on a selection result by the selection means and an acquisition result by the distance acquisition means. Any of the projection systems.   7. The projection system according to claim 1, wherein the light control structure of the optical path switching device includes a switching diffraction grating.   7. The projection system according to claim 1, wherein the light control structure of the optical path switching device includes a polarization beam splitter. An optical path switching device that cooperates with a projection device including a projection unit for projecting an image and switches the projection direction for projection,
A dimming structure that emits incident light from the projection unit of the projection device in either the first direction or a second direction different from the first direction;
An optical path switching device comprising switching control means for controlling the emission direction to be switched in a time-division manner by the dimming structure. Execution in a projection system comprising: a projection device having a part for projecting an image; and a dimming structure that emits incident light in either the first direction or a second direction different from the first direction. A projection control method, comprising:
A projection control method comprising: a switching control step for controlling the emission direction of the light control structure to be switched in a time-sharing manner.