JP7267713B2 - PROJECTION DEVICE, CONTROL METHOD THEREOF, AND PROGRAM - Google Patents

Description

The present invention relates to a projection device, a control method for the projection device, and a program.

2. Description of the Related Art Conventionally, a technique called "pixel shift" is known to make the resolution of a projected image look higher than the resolution of a liquid crystal panel or DMD (Digital Micromirror Device) mounted on a projection device. Specifically, the projection device extracts some pixels from one frame of the image to generate a plurality of still images (hereinafter referred to as sub-frame images) with reduced resolution. Then, the projection device shifts the projection position to a predetermined shift position when projecting a plurality of sub-frame images within the one-frame period. This process of shifting the projection position is called "pixel shift". Specifically, the incident projection light is refracted by a pixel shifting mechanism to shift the optical path to shift the projected pixels. Here, in general, as an easy pixel shift, two sub-frame images are projected at different shift positions to give the user a higher sense of resolution.

On the other hand, the "pixel shift" gradually shifts the pixels over time, so that the transition of the pixels is visually recognized as a blur, and a sufficient effect of increasing the resolution may not be obtained. In particular, if one sub-frame image is continuously projected while the projection device is moving between two shift positions, the pixels will move significantly. Therefore, since the area in which the pixels are visually recognized is large, the projected image may appear blurred.

Therefore, Patent Document 1 discloses an example in which the operation of a pixel shift mechanism is controlled in accordance with the switching timing of subframe images. Specifically, the operation of the pixel shift mechanism is controlled so that the projection position at the time when the subframe images are switched is the middle point between the two shift positions. This control can reduce the amount of pixel transition and suppress image quality deterioration due to image blurring.

JP 2014-211622 A

However, as disclosed in Japanese Unexamined Patent Application Publication No. 2002-200011, the pixel shift mechanism operates by, for example, expanding and contracting a spring, so that the transition speed of the projection position varies due to individual differences and aged deterioration of the pixel shift mechanism. had arisen. Therefore, by controlling the operation of the pixel shift mechanism itself, it is not easy to suppress the blurring of the projected image visually recognized by the user, and thus it has been impossible to provide the user with a higher sense of resolution.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a projection apparatus that can easily suppress blurring of a projected image visually recognized by a user and can give the user a feeling of higher resolution.

A first aspect of the present invention is
generating means for generating a plurality of sub-frame images from one frame of an input image;
projection means for projecting the plurality of sub-frame images;
position adjusting means having an optical member and controlling a projection position of the sub-frame image projected by the projecting means by changing the state of the optical member;
switching control means for switching sub-frame images projected by the projection means according to timing based on the state of the optical member;
with
The position adjustment means controls the projection position within a predetermined range,
The switching control means performs the switching when the optical member is in a state in which the projection position is approximately at the center of the predetermined range.
This is a projection device characterized by:

A second aspect of the present invention is
projection means;
A control method for a projection apparatus, comprising: a position adjusting means having an optical member and controlling a projection position of an image projected by the projection means by changing a state of the optical member,
a generation step of generating a plurality of sub-frame images from one frame of an input image;
a projection control step of projecting the plurality of sub-frame images onto the projection means;
a switching control step of switching sub-frame images projected by the projection means according to timing based on the state of the optical member;
has
The position adjustment means controls the projection position within a predetermined range,
In the switching control step, the switching is performed when the optical member is in a state in which the projection position is approximately at the center of the predetermined range.
A method of controlling a projection device characterized by:

According to the present invention, it is possible to easily suppress the blurring of the projected image visually recognized by the user, and to give the user a feeling of higher resolution.

1 is a configuration diagram of a projection device according to Embodiment 1. FIG. 4A and 4B are diagrams for explaining the state of the position adjustment unit according to the first embodiment; FIG. 4 is a flowchart showing projection control of sub-frame images according to the first embodiment; 4A and 4B are diagrams for explaining a method of generating a subframe image according to the first embodiment; FIG. 4A and 4B are diagrams showing the operation of the position adjustment unit according to the first embodiment; 4A and 4B are diagrams showing switching of images to be projected according to the first embodiment; FIG. The figure which shows the switching of the image to project in a comparative example. FIG. 11 is a diagram showing switching of images to be projected according to Modification 1; Configuration diagram of a projection device according to Embodiment 2 8 is a flowchart showing projection control of sub-frame images according to the second embodiment; FIG. 10 is a diagram showing switching of images to be projected according to the second embodiment; Diagram explaining pixel shift

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings, but the present invention is not limited to the following embodiments.

<Embodiment 1>
The projection apparatus according to Embodiment 1 will be described below. In the first embodiment, a projection apparatus that switches projection of subframe images at appropriate timing by detecting (monitoring) the state of a position adjustment unit (pixel shift mechanism) that controls the projection position will be described. According to this, even when the operation of the position adjusting unit cannot be controlled, the projection device can easily suppress the blurring of the projected image viewed by the user while giving the user a feeling of higher resolution.

[Outline of pixel shift]
First, an outline of "pixel shift" according to the present embodiment will be described. In this embodiment, the projection device firstly converts one frame of the input image into a 2×2 image as indicated by the thick line in FIG. 12(A).
Divide into regions for each pixel. Here, the alphabet in FIG. 12A is a code for identifying each pixel. Next, as shown in FIG. 12(B), the projection device extracts (samples) the "upper left" pixels of the divided regions such as pixel A and pixel C from each region, and displays them with the same resolution as the liquid crystal panel. Generate a first subframe image. It is assumed that the projection device projects this first sub-frame image onto a screen or the like at the “upper left” projection position (first position). For example, looking at a certain pixel 1200 in the first sub-frame image, the pixel 1200 is projected onto the hatched area in FIG. 12(C). Similarly, regarding the "lower right" of the region of the input image, as shown in FIG. 12(D), the projection device to generate a second sub-frame image. Then, the projection device projects the second sub-frame image at a second position shifted by 0.5 pixels in the vertical direction and 0.5 pixels in the horizontal direction from the first position. For example, as shown in FIG. 12(E), the pixel 1200 described above is projected at a position shifted by 0.5 pixel vertically and 0.5 pixel horizontally from the position shown in FIG. 12(C). be. Note that this 0.5 pixel indicates 0.5 pixel in the first sub-frame image (projection image) on the screen (projection plane).

According to this, the second sub-frame image generated by extracting pixels from the "lower right" of the divided area is projected to the "lower right" position compared to the first sub-frame image. Note that the projection device switches between the first sub-frame image and the second sub-frame image and projects them on the screen within the period of one frame of the input image. By shifting the projection position by "pixel shifting" in this way, it is possible to give the viewing user a sense of resolution higher than the resolution of the liquid crystal panel of the projection device.

It should be noted that, as described above, the pixel shift method includes a method of shifting in two directions at an angle of 45 degrees such as "upper left" and "lower right" (two-way drive), and a method of shifting vertically and horizontally (horizontally and vertically) in four directions ( four-way drive). It should be noted that the projection apparatus according to the present embodiment will be described assuming that pixel shifting is performed by two-way driving. Also, as described above, ideally, the first sub-frame image is projected only on the "upper left" and the second sub-frame image is projected only on the "lower right". However, in reality, as shown in FIG. 7A, the projection position (transition position) is gradually changed with the passage of time (time). there is As a result, blurring is visually recognized in the projected image.

[Configuration of projection device 100]
FIG. 1 is a configuration diagram of the projection device 100. As shown in FIG. In the following description using FIG. 1, the components and general functions are described. More detailed processing contents will be described later.

The projection device 100 has a CPU 110 , a ROM 111 , a RAM 112 and an operation section 113 . The projection device 100 also includes an image input unit 120, an image processing unit 121, an image generation unit 124, an element control unit 125, a drive control unit 126, a position adjustment unit 127, an optical system control unit 128, a projection optical system 129, a detection unit. 130 and a switching control unit 131 . Furthermore, the projection device 100 has a light source control section 140 , a light source 141 , a color generation section 142 and a display element 143 .

The CPU 110 controls each functional unit of the projection device 100 via a communication bus (not shown). Further, the CPU 110 can acquire control signals input from the operation unit 113 and control each function unit of the projection device 100 .

The ROM 111 records (stores) a program for the CPU 110 to control each functional unit that configures the projection device 100 .

A RAM 112 temporarily stores control programs and data as a work memory.

The operation unit 113 receives user instructions and transmits control signals to the CPU 110, and includes, for example, switches and dials. Further, the operation unit 113 may transmit a predetermined control signal to the CPU 110 based on the signal acquired by a signal acquisition unit (such as an infrared acquisition unit) that acquires a signal from a remote controller.

The image input unit 120 acquires an image (input image) transmitted from an external device (not shown). The image input unit 120 includes, for example, a composite terminal, a DVI-D terminal, an HDMI (registered trademark; High-Definition Multimedia Interface) terminal, and the like. Here, the external device may be any device such as a personal computer, a smart phone, a hard disk recorder, etc., as long as it can output an image. The image input unit 120 transmits the acquired input image to the image processing unit 121 .

The image processing unit 121 performs image processing such as resolution conversion processing, deformation processing (keystone correction, warping), and color correction processing on the input image obtained from the image input unit 120 . The image processing unit 121 outputs the image-processed input image to the image generation unit 124 and the drive control unit 126 .

The image generator 124 samples (extracts) one frame of the input image acquired from the image processor 121 and generates a plurality of reduced sub-frame images. Here, in this embodiment, the image generator 124 generates two sub-frame images from the one frame. Then, the image generation unit 124 transmits the generated subframe image to the switching control unit 131 together with an image switching signal (vertical synchronization signal) for instructing switching of the subframe image. Note that the frame rate of the projection image increases according to the number of sub-frame images generated by the image generation unit 124 . For example, when two sub-frame images are generated as in this embodiment, the frame rate of the projection image is twice that of the input image acquired from the image processing unit 121 . This is because two sub-frame images are projected as projection images during a period corresponding to one frame of the input image. Also, as described above, the two sub-frame images are called a first sub-frame image (1st frame image) and a second sub-frame image (2nd frame image), respectively.

Note that the image generator 124 may generate a black image, a white image, and an achromatic image. A black image, a white image, and an achromatic image can be displayed while the state of the position adjustment unit 127 is changing, thereby reducing pixel blur. Note that the image generator 124 does not need to generate the black image, the white image, and the achromatic image. For example, the ROM 111 may store the black image, the white image, and the achromatic image in advance.

The element control section 125 drives the electrodes provided under the mirror surface of the micromirror of the DMD of the display element 143 based on the subframe image and the image switching signal obtained from the switching control section 131 .

The drive control unit 126 controls (drives) the operation of the position adjustment unit 127 . For example, the drive control section 126 controls the position adjustment section 127 by controlling the current flowing through the coil attached to the position adjustment section 127 and the voltage applied to the piezoelectric element. Here, the position adjustment unit 127 only needs to operate when a sub-frame image (projection image) is projected onto the screen or the like. It is only necessary to control the position adjustment unit 127 when the position is set.

The position adjustment unit 127 is a pixel shift mechanism (pixel shift device) that shifts the projection position of the projection image to a predetermined position, having the optical member 500 shown in FIG. 2(A). The position adjustment unit 127 changes the state as shown in FIG. Projection images are projected at shift positions shifted by 0.5 pixels in two directions. For example, the position adjusting section 127 may operate by expanding and contracting a spring due to the magnetic force of the attached coil and permanent magnet or the force of the piezoelectric element, and the method of operation is not limited.

In addition, in this embodiment, the case where the position adjustment part 127 is a parallel plate system is demonstrated as an example. The parallel plate type position adjustment unit 127 has a transparent optical member 500 . The optical member 500 has a rectangular plate shape with a refractive index of 1 or more with respect to air, and is normally arranged substantially perpendicular to the light emitted from the display element 143 . The position adjustment unit 127 also controls the projection position by controlling the inclination (angle) of the optical member 500 with respect to the irradiated light. Details of the operation of the position adjustment unit 127 will be described later.

The optical system controller 128 controls the projection optical system 129 and is composed of a control microprocessor. The optical system control unit 128 does not need to be a dedicated microprocessor, and the CPU 110 may execute the same processing as the optical system control unit 128 by a program stored in the ROM 111, for example.

The projection optical system 129 is for projecting the light output from the position adjustment unit 127 onto a projection object such as a screen, and is composed of a plurality of lenses and actuators for lens operation. In other words, in the present embodiment, the projection optical system 129 can be said to be projection means for projecting the light emitted from the light source 141 via the position adjustment section 127 onto a screen or the like as a sub-frame image. Here, the display element 143 is controlled by the switching control unit 131 so that the projection optical system 129 switches and projects a plurality of sub-frame images. By operating the lens with the actuator of the projection optical system 129, enlargement/reduction of the projection image, shift adjustment of the projection position, focus adjustment, and the like can be performed. Therefore, in this embodiment, the projection optical system 129 can be said to be projection means for projecting an image onto a screen or the like.

The detection unit 130 obtains by detecting the state of the position adjustment unit 127 such as inclination, for example. The state detection method performed by the detection unit 130 will be described later in detail. Detecting section 130 outputs information on the detected state of position adjusting section 127 to switching control section 131 as state information.

The switching control unit 131 controls switching timing of subframe images to be projected. Specifically, based on the state information acquired from the detection unit 130, the switching control unit 131 determines the timing of transmitting an image switching signal (vertical synchronization signal) that instructs switching of subframe images to the element control unit 125. Control. In other words, it can be said that the switching control unit 131 switches the sub-frame image projected by the projection optical system 129 using the image switching signal. Further, the switching control section 131 transmits the sub-frame image acquired from the image generating section 124 to the element control section 125 together with the image switching signal. Details of the processing of the switching control unit 131 will be described later.

The light source control unit 140 controls ON/OFF of the light source 141 and controls the amount of light.
The light source 141 outputs light for projecting an image on a screen (not shown), and may be, for example, a halogen lamp, a xenon lamp, a high-pressure mercury lamp, or the like.

The color generator 142 generates red, green, and blue colors by passing the light output from the light source 141 through a color wheel that rotates at high speed. Note that the color generator 142 is not necessary when LEDs corresponding to respective colors are used as the light source 141 .

The display element 143 is a DMD corresponding to red, green, and blue, and is for controlling the transmittance and reflectance of the light generated in red, green, and blue, or the ON/OFF state of the DMD. . The light incident from the light source 141 through the color generation section 142 is reflected by the display element 143 and is irradiated to the position adjustment section 127 . More specifically, the display element 143 is controlled by the element control section 125 in terms of light transmittance and reflectance, or the ON/OFF state of the DMD, according to the image switching signal and the sub-frame image. Accordingly, the display element 143 reflects the light emitted from the light source 141 and irradiates the position adjustment section 127 with the light. Light emitted by the display element 143 is projected as a sub-frame image onto a screen or the like via the position adjustment unit 127 and the projection optical system 129 .

[Regarding the tilt detection method of the detection unit 130]
2A and 2B are diagrams for explaining the processing of the detection unit 130 for detecting the state of the position adjustment unit 127. FIG. In this embodiment, the detector 130 detects the inclination (angle) of the optical member 500 of the position adjuster 127 as the state of the position adjuster 127 . FIG. 2A is a diagram when the surface of the optical member 500 of the position adjusting section 127 is arranged substantially perpendicular to the light emitted from the display element 143. FIG. Here, the range that can be detected by the detection unit 130 is the oblong rectangular range indicated by the dashed line 200 . When the surface of the optical member 500 is substantially vertical (before operation), the position of the predetermined portion of the optical member 500 detected by the detection unit 130 is the hatched portion 201 included in the range indicated by the dashed line 200 .

FIG. 2B is a diagram showing a state when the optical member 500 operates (moves) (after the operation). The position of the predetermined portion of the optical member 500 detected by the detection unit 130 when the operation is performed is a hatched portion 202 included in the range indicated by the dashed line 200 . Then, the detection unit 130 can determine the arc L indicating the trajectory of the operation of the optical member 500 from the positions of the two predetermined parts of the optical member 500 before and after the operation. It is assumed that the optical member 500 operates to draw an arc with a radius of r.

Therefore, the detection unit 130 can calculate the angle θ (degrees) changed by the motion from the arc L and the radius r by the following equation 1. Here, it is assumed that the angle θ is a value close to zero.
θ=(180×L)/(π×r) Equation 1

The detection unit 130 transmits the calculated angle θ to the switching control unit 131 as state information of the position adjustment unit 127 (optical member 500). That is, in this embodiment, the detection unit 130 transmits the tilt of the optical member 500 of the position adjustment unit 127 to the switching control unit 131 as state information. Although the detection unit 130 uses the angle θ as the state information of the position adjustment unit 127, the arc L may be used as the state information, or the position of a predetermined portion of the optical member 500 after operation may be used as the state information. Note that the detection unit 130 only needs to be able to detect the tilt of the optical member 500 of the position adjustment unit 127, and is not particularly limited to an imaging device, an infrared sensor, a photoelectric sensor, or the like.

[Regarding projection control of sub-frame images]
Next, projection control of sub-frame images of the projection device 100 according to the first embodiment will be described. FIG. 3 is a flowchart showing projection control of sub-frame images of the projection device 100 according to the first embodiment. Here, when the image generation unit 124 acquires an input image from the image processing unit 121, this flowchart is started.

(About S300)
In S300, the CPU 110 controls the image generator 124 to generate a sub-frame image from the input image.

Here, the processing of the image generator 124 in S300 will be described in detail. FIG. 4 is a diagram for explaining a method of generating subframe images. (0, 0), (1, 0), etc. shown in FIG. 4 indicate the position (coordinates) of each pixel in one frame of the input image.

The image generator 124 performs sampling (extraction) according to the positions shown in FIG. 4 for one frame of the input image in order to generate a subframe image. Specifically, when one frame of the input image is divided into blocks (regions) of 2×2 pixels, the image generation unit 124 extracts pixels from predetermined positions in each block to generate a sub-frame image. do. In this embodiment, the image generator 124 generates the first sub-frame image from the upper left pixel of each block, and generates the second sub-frame image from the lower right pixel of each block. In FIG. 4, pixels surrounded by thick solid lines are pixels sampled to generate the first sub-frame image, and shaded pixels are sampled to generate the second sub-frame image. is the pixel to be Pixels that are not sampled are not treated as image information. That is, the number of pixels of the subframe image is 1/4 times the number of pixels of the input image.

In the present embodiment, subframe images are generated using the Nearest Neighbor method, which thins out pixels in this way. may be

(About S301)
In S<b>301 , the CPU 110 controls the drive control section 126 to move (drive) the optical member 500 of the position adjustment section 127 . Specifically, the CPU 110 controls the inclination (angle) of the optical member 500 of the position adjusting section 127 with respect to the light irradiated to the position adjusting section 127 . Thereby, the position adjustment unit 127 controls the projection position of the sub-frame image projected by the projection optical system 129 .

Here, the operation of the position adjusting section 127 will be described in detail. 5A to 5F are diagrams showing the relationship between the operation of the position adjustment unit 127 and the projection position of the subframe image. In FIGS. 5A to 5F, the drive control unit 126 controls the optical member 500 of the position adjustment unit 127 to shift the optical path, thereby projecting the projection image to the pixel-shifted position. there is

FIG. 5A shows a state in which the position adjusting section 127 does not change the optical path of the light emitted from the display element 143. FIG. That is, the light incident on the optical member 500 is transmitted as it is and output to the projection optical system 129 . Specifically, the drive control unit 126 performs control so that the angle θ of the optical member 500 is set to 0 degrees so that the optical path is not changed. Here, the angle θ is the angle of the optical member 500 when the angle perpendicular to the incident light is 0 degrees.

FIG. 5B shows the projection position of a pixel P having a subframe image on the projection plane when the angle θ of the optical member 500 of the position adjustment unit 127 is 0 degrees, as shown in FIG. 5A. is shown. Here, the center position of the pixel P when the optical path is not controlled is called a center pixel position 501 . According to this, the sub-frame image can be projected at the same position as when the position adjustment unit 127 does not control the projection position.

FIG. 5C shows the operating state of the position adjustment unit 127 when projecting the pixel P to the upper left position with respect to the center pixel position 501 .

The drive control unit 126 controls the inclination of the optical member 500 so that the angle θ=−α degrees. Then, the light incident on the optical member 500 is output to the projection optical system 129 with the optical path of the incident light shifted due to refraction. As a result, as shown in FIG. 5D, the center position of the pixel P moves from the center pixel position 501 to the center pixel position 502 located on the upper left. Here, the center pixel position 502 is a position shifted by 0.25 pixels in the horizontal and vertical directions from the center pixel position 501 .

FIG. 5E shows the operating state of the position adjustment unit 127 when projecting the pixel P to the lower right position with respect to the center pixel position 501 .

The drive control unit 126 controls the inclination of the optical member 500 so that the angle θ=+α degrees. Then, the light incident on the optical member 500 is output to the projection optical system 129 with the optical path of the incident light shifted due to refraction. As a result, as shown in FIG. 5F, the center position of the pixel P moves from the center pixel position 501 to the center pixel position 503 located at the lower right position. Here, the center pixel position 503 is a position shifted by 0.25 pixels in the horizontal and vertical directions from the center pixel position 501 . Also, the central pixel position 503 and the central pixel position 502 differ by 0.5 pixels in the horizontal and vertical directions.

In this manner, the CPU 110 changes the optical path of light emitted from the display element 143 by controlling the drive control section 126 to move (drive) the position adjustment section 127 . Thereby, the projection device 100 can move the projection position of the sub-frame image.

(About S302)
In S302, the CPU 110 controls the detection unit 130 to detect the inclination of the optical member 500 of the position adjustment unit 127 (the state of the position adjustment unit 127), calculates the angle θ as the state information as described above, It is transmitted to the switching control unit 131 .

(About S303)
In S303, the CPU 110 controls the switching control unit 131 to transmit an instruction to switch subframe images to the element control unit 125 as an image switching signal. Note that the timing for switching the subframe images is determined based on the state information detected by the detection unit 130 . Then, the CPU 110 performs projection control for projecting the sub-frame image onto the projection optical system 129 according to the sub-frame image input from the switching control unit 131 to the element control unit 125 . Here, the determination of the switching timing of the subframe images performed by the switching control unit 131 will be described in detail.

FIG. 6A is a diagram showing the relationship between transition positions of sub-frame images and switching timings of sub-frame images. In FIG. 6A, the vertical axis indicates the transition position of the subframe images, that is, the position of the subframe images on the projection plane. Specifically, transition position=0 indicates the projection position (center position) of the sub-frame image when the angle θ of the optical member 500 is 0 degrees. Moreover, the transition position=+0.25 pic indicates a position where the projection position is shifted 0.25 pixels to the upper left from the center position. The position where the projection position transitions is shown at the bottom right of 25 pixels. That is, as shown in FIG. 6A, in the present embodiment, the projection device 100 projects the sub-frame image (projection image) in the range where the transition position is -0.25 pic to +0.25 pic.

In FIG. 6A, the horizontal axis indicates time, and time t1 and time t2 indicate times at which the projected subframe images are switched. Also, in the following description, the projected image indicated by diagonal lines in FIG. A second sub-frame image 601 is the projected image that has been grayed out. Also, let 0 be the time when the display of the first sub-frame image 600 is started.

Projection device 100 projects first sub-frame image 600 from time 0 to t1, and as shown in FIG. do. At time t<b>1 , the detection unit 130 detects that the transition position is 0 (angle θ=0), and the switching control unit 131 switches the projected image to the second sub-frame image 601 . Similarly, the projection device 100 projects the second sub-frame image 601 from time t1 to t2, and the switching control unit 131 switches the projected image to the first sub-frame image 600 at time t2.

That is, when the transition position of the subframe image is 0, which is the center of the range of -0.25 to +0.25pic, it is detected that the state information is θ=0, and the subframe image switching is performed. will be Therefore, the switching control unit 131 switches the sub-frame image when the state information corresponding to the time point of projecting the sub-frame image at the center position of the projection range is detected. Note that it is not always necessary to switch the subframe images when the transition position of the subframe images is 0 pic. At this point, sub-frame image switching may occur.

FIG. 6B is a schematic diagram showing the transition width (transition width) until each subframe image is switched. By the operation described above, the transition width of each subframe image can be set to 0.25 pixels in the horizontal and vertical directions. This is shorter than the transition width of each sub-frame image in a comparative example, which will be described later with reference to FIG. 7(A). Therefore, by switching the sub-frame image at the time of projecting the sub-frame image at the center position of the projection range, the visibility of blurring of the image can be reduced. Further, since the projection apparatus 100 switches the sub-frame images to be projected based on the tilt of the optical member 500, the sub-frame images are switched at appropriate timing even when the position adjustment unit 127 (pixel shift mechanism) is degraded. be able to.

[Effect of switching sub-frame images when θ=0]
The effect of switching the sub-frame images when θ=0, that is, when projecting the sub-frame images at the center position of the projection range, will be described in detail below.

FIG. 7A is a diagram showing the relationship between the projection position of a subframe image and the switching timing of the subframe image in a comparative example with respect to this embodiment. Here, the projection device according to the comparative example is assumed to be a projection device 100′, and the projection device 100′ has the same functional units as the projection device 100 according to the present embodiment, and a “switching control unit 131′”. etc. are indicated with "'". Also, the vertical axis and horizontal axis in FIG. 7(A) are the same as those in FIG. 6(A). Here, the time when the second sub-frame image 601 is projected and the transition position of the second sub-frame image 601=0 is defined as 0.

The projection device 100′ projects the second sub-frame image 601 from time 0 to t3, and as shown in FIG. 7A, the transition position of the second sub-frame image 601 changes from 0 to +0.25 pic. . Then, at time t3, the switching control section 131' switches the image to be projected onto the first sub-frame image 600 according to the image switching signal.

Also, the projection device 100' projects the first sub-frame image 600 from time t3 to t4. Then, at time t4, when the transition position of the first sub-frame image 600=-0.25 pic, the switching control unit 131' switches the image to be projected to the second sub-frame image 601 according to the image switching signal. Further, the projection device 100′ projects the second sub-frame image 601 from time t4 to t5, and at time t5, when the transition position=+0.25 pic, the image switching signal causes the image to be projected to be projected to the first sub-frame. Switch to the frame image 600 .

FIG. 7B shows a transition width (transition width) of a subframe image before switching when the switching control unit 131 ′ switches subframe images as shown in FIG. 7A . By the operation described above, the center position of each subframe image shifts by 0.5 pixels in the horizontal and vertical directions until the projected image is switched. Therefore, since the transition width of each sub-frame image is larger than that of the present embodiment, the blurring of the image appears large. In other words, instead of switching the subframe images at the transition position of the subframe image=±0.25 pic, it is better to switch the subframe image when the transition position=0 pic as in the present embodiment. The blur of the rendered image can be reduced. Of course, the sense of blur also depends on the transition speed of pixels, and the faster the transition speed, the less noticeable the blur. However, since there is a limit to the speed at which the position adjustment unit 127 can change the tilt of the optical member 500, there are cases where the pixel transition speed cannot be increased. Even in such a case, the present embodiment is effective because the transition width affects the feeling of blurring.

In this embodiment, the subframe image to be projected is switched when the transition position of the subframe image is 0, but this is not the only option. For example, if the subframe image transitions in the transition position range of 0 to +0.5 pic, the subframe image to be projected may be switched when the transition position=+0.25 pic. That is, since it is sufficient to suppress the transition width of each subframe image, it is sufficient to switch the subframe image to be projected at the center position of the range in which the projection position transitions. Such control can be realized, for example, if a table or the like storing the correspondence between the transition position and the inclination (angle θ) of the optical member 500 of the position adjusting section 127 is generated in advance.

In this embodiment, the case of two-direction driving in which two sub-frame images are generated from one frame of an input image and projected is described, but four sub-frame images are generated from one frame of an input image and projected. It is also applicable to four-direction drive. That is, even in the case of four-direction driving, the subframe images to be projected may be switched according to the state information so that the transition width of each subframe image is minimized. More specifically, the switching control unit 131 may switch the subframe image to be projected, for example, at the timing when the absolute value of the angle θ takes the minimum value.

In this embodiment, the optical member 500 included in the position adjusting section 127 is explained as being of a transmissive type, but may be of a reflective type. Even if the optical member 500 is of a reflective type, it is possible to adjust the projection position of the projected image by adjusting the inclination of the optical member 500 with respect to the incident light. That is, as described above, the detection unit 130 detects the tilt of the optical member 500, so that the projection device 100 can switch subframe images to be projected at appropriate timing.

As described above, according to the first embodiment, by detecting the state of the position adjustment unit, blurring of the projected image viewed by the user can be suppressed even when the operation of the position adjustment unit (pixel shift mechanism) cannot be controlled. Further, even when the transition speed of the projection position varies due to individual differences in the position adjustment unit or deterioration over time, blurring of the projected image visually recognized by the user can be suppressed.

[Modification 1]
In the first embodiment, since the transition width of each subframe image is 0.25 pic, which is larger than 0, there is a possibility that blurring of the projected image visually recognized by the user remains. Therefore, in modification 1, the projection device 100 that sets the transition width of each subframe image to 0 will be described.

Note that the configuration of each functional unit of the projection device 100 according to this modified example is the same as the configuration of each functional unit of the projection device 100 according to Embodiment 1, so detailed description of each functional unit will be omitted. Since this modification differs from the first embodiment only in the processing of S303, S303 according to this modification will be described below with reference to FIGS. 8A and 8B.

In S303, as shown in FIG. 8A, the switching control unit 131, based on the state information, shifts the projected image to the first Switch to the one-subframe image 600 . Based on the state information, the switching control unit 131 switches the image to be projected to the second sub-frame image 601 when the angle θ=+α (when the transition position=−0.25 pic). Based on the state information, the switching control unit 131 switches the image to be projected to the black image when the angle θ≠±α (when the transition position≠±0.25 pic). According to this, when the tilt of the optical member 500 of the position adjustment unit 127 changes, that is, when the projection position changes, a black image is displayed instead of the sub-frame image. Note that the image to be projected does not have to be a black image, and may be a white image or an achromatic image.

According to this modification, as shown in FIG. 8B, the transition width between the first sub-frame image and the second sub-frame image can be set to zero. Therefore, blurring of the projected image can be made more difficult to see than in the first embodiment.

<Embodiment 2>
In the first embodiment, the projection device switches subframe images by detecting the state of the position adjustment unit. In the second embodiment, the state of the position adjustment unit is estimated without being detected, and the switching timing of the sub-frame images is delayed by a predetermined period (time) after the projection position starts to change, thereby adjusting the sub-frame images appropriately. A switching projection device will be described.

[Configuration of projection device 800]
First, the configuration of the projection device 800 will be described using FIG. FIG. 9 is a configuration diagram of a projection device 800 according to the second embodiment. In the explanation using this block diagram, the constituent elements and the general functions will be explained. Details of the processing will be described later.

The projection device 800 includes a CPU 110, a ROM 111, a RAM 112, an operation unit 113, an image input unit 120, an image processing unit 121, an image generation unit 124, an element control unit 125, a drive control unit 126, a position adjustment unit 127, and an optical system control unit 128. , and a projection optical system 129 . Furthermore, the projection device 800 has a light source control section 140 , a light source 141 , a color generation section 142 and a display element 143 . Since these perform the same processing as the functional units with the same reference numerals in the first embodiment, detailed description thereof will be omitted. The projection device 800 also has a switching control section 831 .

The switching control unit 831 controls switching timing of subframe images to be projected. Here, unlike the first embodiment, the state information indicating the inclination (angle θ) of the optical member 500 of the position adjustment unit 127 is not input because the detection unit 130 does not exist. Therefore, the switching control section 831 estimates the timing at which the angle θ of the position adjusting section 127 becomes zero. Then, the switching control unit 831 delays the element control unit 125 by a predetermined period from the image switching timing of the comparative example described with reference to FIG. is transmitted at the estimated timing.

[Regarding projection control of sub-frame images]
Next, projection control of the sub-frame images of the projection device 800 according to the second embodiment will be described with reference to FIG. FIG. 10 is a flowchart showing projection control of sub-frame images of the projection device 800 according to the second embodiment. Here, when the image generation unit 124 acquires an input image from the image processing unit 121, this flowchart is started.

Since S300 and S301 are the same as the processes with the same reference numerals described in the first embodiment, detailed description thereof will be omitted.

In S<b>902 , the CPU 110 controls the switching control unit 831 to transmit an image switching signal to the element control unit 125 to instruct switching of subframe images.

Here, the timing at which the switching control unit 831 instructs switching of subframe images will be described in detail. FIGS. 11A to 11C are diagrams showing the relationship between transition positions of subframe images and switching timings of subframe images. The vertical axis of FIG. 11A indicates the transition position of the subframe images, that is, the position of the subframe images on the projection plane. The horizontal axis indicates time, and times t2 and t4 indicate times when the transition width of the subframe image is zero. In the following, it is assumed that the first sub-frame image 1001 and the second sub-frame image 1000 are projected while being switched. Let 0 be the time at which the second sub-frame image 1000 is displayed when the transition position of the second sub-frame image 1000 is -0.25 pic.

FIG. 11B shows the timing at which the switching control section 831 transmits the image switching signal to the element control section 125, as in the projection apparatus 100' of the comparative example described above. On the other hand, FIG. 11C shows the timing at which the switching control section 831 delays the image switching signal and transmits it to the element control section 125 with respect to the case of FIG. 11B. Here, in FIGS. 11B and 11C, the vertical axis indicates the voltage of the image switching signal, and the horizontal axis indicates time. That is, the image switching signal is transmitted to the element control section 125 at the time when the voltage value changes from 0V to 3.3V.

That is, in FIG. 11B, at time t1 and time t3 when the transition position of the subframe image is ±0.25 pic, the switching control unit 831 outputs the image switching signal so as to switch the subframe image. . On the other hand, in FIG. 11C, at time t2 and time t4 when the transition position of the subframe image is ±0pic, the switching control unit 831 outputs an image switching signal to switch the subframe image.

Specifically, the projection device 800 projects the second sub-frame image 1000 from time 0 to t2, and as shown in FIG. to 0. Here, at time t1, the projection position (transition position) of the second sub-frame image 1000 starts to change. The timing of transmission is delayed by waiting for a predetermined period of time. Then, as shown in FIG. 11C, at time t2, that is, at the timing when the transition position becomes 0, the switching control section 831 transmits an image switching signal to the element control section 125, and the first subframe image 1001 switch the projected image. That is, the switching control unit 831 estimates that the angle θ of the optical member 500 of the position adjustment unit 127 is 0 at the timing when a predetermined period has passed since the projection position of the subframe image changed. It can also be said that the switching control unit 831 acquires the state of the position adjustment unit 127 by the estimation.

Note that the predetermined period is, for example, a period (time) from time t1 to t2, from when the tilt of the optical member 500 of the position adjustment unit 127 starts to change until it reaches a predetermined tilt (angle θ=0). is the period (hours) of , and is set to a value adjusted (set) in advance before shipment from the factory. Further, whether or not the projection position has started to change can be determined, for example, by detecting that a driving force or voltage is applied to the position adjustment unit 127 or by capturing a projected image.

Similarly, the projection device 800 projects the first sub-frame image 1001 from time t2 to t4, and the switching control unit 831 switches the image to be projected to the second sub-frame image 1000 at time t4. By the operation described above, the transition width of each subframe image can be set to 0.25 pixels in the horizontal and vertical directions, as in the first embodiment.

In this embodiment, the switching control unit 831 estimates the time at which the angle θ of the position adjustment unit 127 becomes 0 using a value adjusted in advance before shipment from the factory, and transmits the image switching signal. determines, but is not limited to, the timing of For example, the switching control unit 831 acquires a moving range of the image being projected on the screen by capturing an image of the screen by the imaging unit or the like, and adjusts the position when the image is projected at the center position of the range. It may be assumed that the angle θ of the portion 127 is zero. That is, the switching control unit 831 may transmit the image switching signal when determining that the image is projected at the center position of the range.

As in Modification 1 described above, when the projection position changes (when the tilt of the optical member 500 changes), a black image, a white image, or an achromatic image may be projected. . Specifically, when the projection position starts to change, the switching control unit 831 switches the image to be projected to the black image, and after a predetermined period of time has elapsed, switches the image to be projected to the sub-frame image. Here, the predetermined period is, for example, the time until the angle θ changes from −α to +α as shown in FIGS. 5(A) to 5(F). According to this, it is possible to further suppress the visibility of the blur in the projected image.

As described above, according to the second embodiment, the state (inclination) of the position adjustment unit itself is estimated without being detected, and the switching timing of the sub-frame images is delayed by a predetermined period after the projection position starts to change. Switch images. This makes it possible to reduce image blur. In other words, even when the state of the position adjustment unit cannot be detected, the same effect as in the first embodiment can be obtained.

Note that each functional unit in each of the above-described embodiments and modifications may or may not be separate hardware. Functions of two or more functional units may be implemented by common hardware. Each of the multiple functions of one functional unit may be implemented by separate hardware. Two or more functions of one functional unit may be realized by common hardware. Also, each functional unit may or may not be realized by hardware such as ASIC, FPGA, and DSP. For example, the device may have a processor and a memory (storage medium) in which a control program is stored. The functions of at least some of the functional units of the device may be realized by the processor reading out and executing the control program from the memory.

(Other embodiments)
The present invention supplies a program that implements one or more functions of the above embodiments to a system or apparatus via a network or a storage medium, and one or more processors in the computer of the system or apparatus reads and executes the program. It can also be realized by processing to It can also be implemented by a circuit (for example, ASIC) that implements one or more functions.

100: projection device, 127: position adjustment section, 129: projection optical system 130: detection section, 131: switching control section, 500: optical member

Claims (9)

generating means for generating a plurality of sub-frame images from one frame of an input image;
projection means for projecting the plurality of sub-frame images;
position adjusting means having an optical member and controlling a projection position of the sub-frame image projected by the projecting means by changing the state of the optical member;
switching control means for switching sub-frame images projected by the projection means according to timing based on the state of the optical member;
with
The position adjustment means controls the projection position within a predetermined range,
The switching control means performs the switching when the optical member is in a state in which the projection position is approximately at the center of the predetermined range.
A projection device characterized by: Further comprising detecting means for acquiring by detecting the state of the optical member,
2. The projection device according to claim 1, characterized in that: The switching control means is
controlling the timing based on a preset time from when the state of the optical member starts to change until the optical member reaches a predetermined state;
2. The projection device according to claim 1, characterized in that: The position adjusting means is
controlling the projection position by controlling the inclination of the optical member with respect to the light emitted from the light source to the optical member;
4. The projection device according to any one of claims 1 to 3, characterized in that: wherein the state of the optical member is an inclination of the optical member with respect to light emitted from a light source to the optical member;
5. The projection device according to any one of claims 1 to 4, characterized in that: The switching control means performs the switching when the optical member is substantially perpendicular to the light emitted from the light source to the optical member.
6. The projection device according to any one of claims 1 to 5, characterized in that: The approximate center position of the predetermined range is
substantially the same position as the projection position when the position adjusting means does not control the projection position;
7. The projection device according to any one of claims 1 to 6, characterized in that: projection means;
A control method for a projection apparatus, comprising: a position adjusting means having an optical member and controlling a projection position of an image projected by the projection means by changing a state of the optical member,
a generation step of generating a plurality of sub-frame images from one frame of an input image;
a projection control step of projecting the plurality of sub-frame images onto the projection means;
a switching control step of switching sub-frame images projected by the projection means according to timing based on the state of the optical member;
has
The position adjustment means controls the projection position within a predetermined range,
In the switching control step, the switching is performed when the optical member is in a state in which the projection position is approximately at the center of the predetermined range.
A control method for a projection device, characterized by: A program for causing a computer to execute each step of the control method according to claim 8 .

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