JP5540493B2 - Method for measuring position or tilt of projection plane relative to projection optical system, image processing method for projected image using the measurement method, projector for executing the image processing method, program for measuring position or tilt of projection plane with respect to projection optical system - Google Patents

Description

  The present invention relates to a projector having a projection optical system that projects light onto a projection surface.

  In a projector, an image is displayed by projecting image light representing an original image displayed on a liquid crystal panel onto a projection screen via a projection optical system. However, the projection image of the projector may cause distortion such as trapezoidal distortion depending on the state of the projection screen (for example, the position and tilt angle of the projection screen with respect to the projection optical system, the shape of the surface of the projection screen, etc.). . Until now, various techniques for reducing distortion of a projected image by executing correction processing on the original image in accordance with the state of the projection screen have been proposed (Patent Document 1, etc.).

JP 2001-061121 A JP 2001-320652 A JP 2004-140845 A

  In general, the trapezoidal distortion correction of a projector is performed by measuring the position and tilt angle of the projection screen with respect to the projection optical system by triangulation. However, when the zoom ratio of the projection optical system is adjusted by a zoom mechanism or the like, the focal length also changes. In the above triangulation, since the focal length of the projection optical system is used as an internal parameter of the projection optical system, the measurement accuracy of the triangulation may be lowered due to the change of the focal length. As described above, when the projection screen is measured by triangulation, there is a problem that the measurement accuracy is deteriorated due to the change or error of the internal parameters of the projection optical system. Such a problem is not limited to projectors equipped with a zoom mechanism, but is a problem common to optical devices that measure the projection target using the projection light of the projection optical system.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a technique capable of easily and accurately executing a projection target using projection light of a projection optical system.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1]
A method for measuring the position or inclination of the projection plane relative to the projection optical system using a projector including a projection optical system that projects image light representing an image onto the projection plane,
(A) the projector projecting a measurement image including two or more specific points having specific coordinates in the image plane onto the projection plane;
(B) The projector takes a measurement projection image in which the measurement image is projected on the projection plane by an imaging unit whose position relative to the projection optical system is fixed, at a preset zoom ratio. And a process of
(C) the projector detecting an imaging measurement line corresponding to a measurement line that can be formed on the projection plane by the specific point from an image captured by the imaging unit;
(D) the projector determining a position or an inclination of the projection plane according to the imaging measurement line;
A method comprising:
According to this method, it is possible to measure the position or inclination of the projection plane that is the projection target by detecting the imaging measurement line. Therefore, it is possible to easily and accurately carry out the measurement of the projection target using the projection light of the projection optical system.

[Application Example 2]
A method described in application example 1,
The projection optical system includes a zoom mechanism that adjusts a zoom ratio of the projection optical system,
The measurement image is projected onto the projection plane such that the optical axis of the projection optical system passes on the measurement line or an extension line thereof.
According to this method, regardless of the zoom ratio of the projection optical system, the position or inclination of the projection plane can be uniquely specified with respect to the detected imaging measurement line. Therefore, it is possible to easily and accurately carry out the measurement of the projection target using the projection light of the projection optical system.

[Application Example 3]
A method described in Application Example 1 or Application Example 2,
(E) The projector includes a step of executing a predetermined control process for controlling the image light by using the determined position or inclination of the projection plane.
According to this method, the image light is controlled in accordance with the measured position or inclination of the projection plane, so that the image display performance of the projector is improved.

[Application Example 4]
The method according to any one of Application Example 1 to Application Example 3,
The position of the projection plane includes the position of the intersection of the projection plane and the optical axis of the projection optical system,
The predetermined control process includes a focus process of adjusting a focus of the projection optical system according to a distance between a main point of the projection optical system and the intersection.
According to this method, the focus of the projected image projected and displayed on the projection target is adjusted according to the measured position of the intersection point, so that the image display performance of the projector is improved.

[Application Example 5]
The method according to any one of Application Example 1 to Application Example 4,
The predetermined control process includes a correction process for correcting a trapezoidal distortion of a projected image projected and displayed on the projection plane.
According to this method, since the trapezoidal distortion of the projected image projected and displayed on the projection target is adjusted according to the measured position and inclination of the projection surface, the image display performance of the projector is improved.

[Application Example 6]
An image processing method using a projection image of a projector including a projection optical system that projects image light representing an image onto a projection plane,
(A) the projector projecting a measurement image including two or more specific points having specific coordinates in the image plane onto the projection plane by the projection optical system;
(B) The projector takes a measurement projection image in which the measurement image is projected on the projection plane by an imaging unit whose position relative to the projection optical system is fixed, at a preset zoom ratio. And a process of
(C) the projector detecting an imaging measurement line corresponding to a measurement line that is included in the captured image captured by the imaging unit and can be formed on the projection plane by the specific point;
(D) the projector exists on the projection plane, and the projection measurement line corresponding to the measurement line is a first plane defined by the principal point of the imaging unit and the imaging measurement line; and Obtaining a line of intersection between a principal plane of the projection optical system and a second plane defined by the measurement line;
A method comprising:
According to this method, by detecting a photographed image measurement line from a photographed image, a projection measurement line that is a projection image of the measurement line in a three-dimensional space can be specified. By specifying the projection measurement line, it is possible to easily and accurately carry out surveying of the projection plane that is the projection target.

[Application Example 7]
The method according to Application Example 6,
The projection optical system includes a zoom mechanism that adjusts a zoom ratio of the projection optical system,
The method, wherein the measurement image is projected onto the projection plane so that an optical axis of the projection optical system passes through a straight line of the measurement line or the straight line.
According to this method, the second plane can be prepared in advance regardless of the zoom ratio of the projection optical system. Therefore, it is possible to easily and accurately carry out the measurement of the projection target using the projection light of the projection optical system.

[Application Example 8]
The method according to Application Example 6 or Application Example 7,
(E) The projector includes a step of executing a predetermined control process for controlling the image light using the obtained position or inclination of the intersection line.
According to this method, the image light is controlled in accordance with the position or inclination of the measured projection measurement line. Thereby, the image display performance of the projector is improved.

[Application Example 9]
The method according to any one of Application Example 6 to Application Example 8,
The position of the projection plane includes the position of the intersection of the projection plane and the optical axis of the projection optical system,
The predetermined control process includes a focus process of adjusting a focus of the projection optical system according to a distance between a main point of the projection optical system and the intersection.
According to this method, the focus of the projected image projected and displayed on the projection target is adjusted according to the measured position of the intersection point, so that the image display performance of the projector is improved.

[Application Example 10]
The method according to any one of Application Example 6 to Application Example 9,
The predetermined control process includes a correction process for correcting a trapezoidal distortion of a projected image projected and displayed on the projection plane.
According to this method, since the trapezoidal distortion of the projected image projected and displayed on the projection target is adjusted according to the measured projection measurement line, the image display performance of the projector is improved.

[Application Example 11]
A projector that displays image projection by projecting image light representing an image on a projection surface,
A light modulation unit that forms a panel image for generating the image light by modulating the illumination light on a panel surface irradiated with the illumination light, and emits the image light;
A projection optical system for projecting the image light;
In the image plane, a measurement image storage unit for storing a measurement image including two or more specific points having specific coordinates;
An imaging unit that captures a measurement projection image, which is fixed at a relative position with respect to the projection optical system and the measurement image is projected on the projection plane, at a preset zoom ratio;
A control unit that controls the projection optical system and the light modulation unit;
With
The controller is
An imaging measurement line corresponding to a measurement line included in the captured image by the imaging unit and formed on the projection plane by the specific point;
In accordance with the imaging measurement line, determining the position or tilt angle of the projection plane,
A projector that corrects a display state of the projection image according to the determined position or inclination angle of the projection surface.

[Application Example 12]
The projector according to application example 11,
The measurement line includes at least first and second measurement lines having different inclinations,
The control unit is a projector that corrects trapezoidal distortion or focus of the projected image.

[Application Example 13]
A program that is executed in a projector including a projection optical system that projects image light representing an image on a projection plane, and that measures the position or tilt of the projection plane with respect to the projection optical system,
A function of projecting a measurement image including two or more specific points having specific coordinates within the image plane onto the projection plane;
A function of photographing a measurement projection image in which the measurement image is projected on the projection plane by an imaging unit fixed at a position relative to the projection optical system at a preset magnification;
A function of detecting an imaging measurement line corresponding to a measurement line that can be formed on the projection plane by the specific point from a captured image by the imaging unit;
A function of determining the position or inclination of the projection plane according to the imaging measurement line;
A program comprising:

  The present invention can be realized in various forms. For example, a method for measuring the position or inclination of the projection plane with respect to the projection optical system, an optical apparatus that executes the method, a control method for the optical apparatus, and the like The present invention can be realized in the form of a control device, a computer program for realizing the functions of those methods or devices, a recording medium storing the computer program, and the like.

Next, embodiments of the present invention will be described in the following order based on examples.
A. First embodiment:
B. Second embodiment:
C. Third embodiment:
D. Variations:

A. First embodiment:
FIG. 1 is a block diagram showing an outline of the internal configuration of a projector as an embodiment of the present invention. The projector 100 displays image by projecting image light representing an image on a projection surface such as a projection screen SC.

  The projector 100 includes an A / D conversion unit 110, a central processing unit 120 (CPU 120), a video processor 134, an internal memory 160 (RAM 160), a nonvolatile storage unit 170 (ROM 170), and a captured image memory 182. It has. The projector 100 further includes an illumination optical system 140, a liquid crystal panel 130, a projection optical system 150, a liquid crystal panel drive unit 132, a zoom lens drive unit 155, an imaging unit 180, a remote control control unit 190, and a remote control 191. And. The CPU 120, the liquid crystal panel driving unit 132, the video processor 134, the zoom lens driving unit 155, the RAM 160, the ROM 170, the imaging unit 180, the captured image memory 182 and the remote control control unit 190 are internal buses. They are connected to each other via 102.

  Projector 100 accepts an instruction input related to operation of projector 100 from a user via remote controller 191. The remote control unit 190 receives a signal indicating an instruction input by the user from the remote control 191 and transmits the signal to the CPU 120. CPU 120 controls each component of projector 100 in accordance with the signal.

  The projector 100 receives an image signal representing a display image from an external device such as a DVD player or a personal computer (not shown) via the cable 300. An analog image signal input from an external device is converted into a digital image signal by the A / D converter 110 and supplied to the video processor 134.

  The video processor 134 includes a trapezoidal distortion correction unit 136. The trapezoidal distortion correction unit 136 performs keystone correction on the digital image signal input from the A / D conversion unit 110. The keystone correction will be described later. Hereinafter, in this specification, an image represented by a digital image signal output from the A / D converter 110 is referred to as an “original image before correction”. On the other hand, an image represented by the digital image signal after being corrected by the video processor 134 is referred to as “original image after correction” or simply “original image”.

  Here, the CPU 120 includes an imaging measurement line detection unit 121, a projection measurement line detection unit 122, a projection plane detection unit 123, a projection distance measurement unit 124, and a projection angle measurement unit 125. The parameters used in the trapezoid correction executed by the trapezoidal distortion correction unit 136 are determined by the cooperation processing of these constituent units 121 to 125. Specific contents of the cooperation processing will be described later. In addition, each component 121-125 with which CPU120 is provided is implement | achieved as a computer program stored in RAM160, and is good also as what is read into CPU120 as needed. On the other hand, the trapezoidal distortion correction unit 136 of the video processor 134 may be configured in hardware.

  The video processor 134 outputs a digital image signal representing the corrected original image to the liquid crystal panel driving unit 132. The liquid crystal panel driving unit 132 drives the liquid crystal panel 130 based on the digital image signal. The liquid crystal panel 130 modulates the illumination light emitted from the illumination optical system 140 into image light representing an image. The image light output from the liquid crystal panel 130 is projected onto the projection screen SC via the projection optical system 150. Hereinafter, in the present specification, an image projected and displayed on the projection screen SC is referred to as a “projected image”.

  Note that the projection optical system 150 includes a zoom lens 152. The focal length of the zoom lens 152 is adjusted by the zoom adjustment motor 156 and the focus adjustment motor 157 of the zoom lens driving unit 155. Thereby, the display magnification and focus of the projected image are adjusted.

  The imaging unit 180 can shoot the projection screen SC on which the projection image is displayed. The projector 100 can detect the arrangement state of the projection screen SC with respect to the projector 100 based on the captured image. Here, the “arrangement state of the projection screen SC” means the position and the inclination angle of the projection screen SC with respect to the projector 100.

  The imaging unit 180 has a fixed relative position with respect to the projection optical system 150, and can capture images at a preset magnification. The imaging unit 180 is configured by an image sensor such as a CMOS sensor or a CCD sensor, for example. The imaging data of the imaging unit 180 is stored directly in the captured image memory 182 from the imaging unit 180. The CPU 120 can read the image data from the captured image memory 182 via the internal bus 102.

  FIG. 2A is a schematic front view showing the appearance of the projector 100. In FIG. 2A, the three-dimensional directions (x, y, z directions) are indicated by arrows for convenience of explanation. The projector 100 has a substantially rectangular parallelepiped shape, and the projection optical system 150 and the imaging unit 180 are arranged on the same surface 100s along the arrow x direction and the arrow y direction. More specifically, the projection optical system 150 and the imaging unit 180 are arranged in parallel along the arrow x direction (long-side direction) of the surface 100s, and are located at a position close to the opposing short side. Is provided. Note that a leg portion 105 is provided on the bottom surface of the projector 100. The projector 100 can move both the optical axis of the projection optical system 150 and the optical axis of the imaging unit 180 along the arrow y direction in the drawing by adjusting the height of the leg portion 105.

  2B and 2C schematically illustrate a state in which the projection optical system 150 of the projector 100 projects image light onto the projection screen SC and a state in which the imaging unit 180 images the projection screen SC. It is explanatory drawing. Note that the directions indicated by the arrows x, y, and z shown in FIGS. 2B and 2C correspond to the directions indicated by the arrows x, y, and z in FIG.

  The projection optical system 150 and the imaging unit 180 are the optical axis OAp and the imaging unit of the projection optical system 150 when the projector 100 is viewed along the top surface direction (the direction along the arrow y) (FIG. 2B). The optical axis OAi of 180 is arranged so as to intersect. Further, when viewed along the side surface direction (direction along the arrow x) of the projector 100 (FIG. 2C), the two optical axes OAp and OAi substantially overlap each other. In FIG. 2C, the optical axis OAi is not shown.

Here, a region sandwiched between _two straight lines PA ₁ and PA ₂ extending radially from the projection optical system 150 to the projection screen SC indicates a projection region of image light. An area sandwiched between _two broken lines SA ₁ and SA ₂ extending radially from the imaging unit 180 to the projection screen SC indicates an imaging area by the imaging unit 180. As described above, the imaging unit 180 can capture the entire projection image of the projection screen SC.

  3A to 3C are explanatory diagrams for explaining the relationship among an original image formed on the liquid crystal panel 130, a projected image, and a captured image of the imaging unit 180. FIG. FIG. 3A is a front view schematically showing the liquid crystal panel 130 (FIG. 1). The liquid crystal panel 130 has a substantially rectangular panel surface 130s. The liquid crystal panel 130 has an image forming area IF for forming a panel image for modulating the illumination light into image light on the panel surface 130s. The image forming area IF is composed of pixels of m × n dots (m and n are arbitrary real numbers). The image forming area IF of this embodiment is formed as an inner peripheral area that is smaller by two dots than the outer periphery of the panel surface 130s, but the size of the image forming area IF can be arbitrarily set.

  FIG. 3B is a schematic diagram showing a state in which the all-white projection image PI is projected and displayed on the projection screen SC. The all-white projection image PI is illustrated by hatching for convenience. When the projector 100 and the projection surface of the projection screen SC do not face each other and the projection surface of the projection screen SC has an inclination with respect to the projector 100, the all-white projection image PI corresponds to the inclination. The shape is distorted.

  FIG. 3C is a schematic diagram showing a captured image SI when the imaging unit 180 captures the projection screen SC on which the all white projected image PI of FIG. 3B is displayed. Since the imaging unit 180 captures images obliquely with respect to the projection screen SC from the lateral position of the projection optical system 150, the projection screen SC is distorted into a substantially trapezoidal shape.

  In general, projectors are often not arranged so that the optical axis of the projection optical system and the projection plane of image light intersect perpendicularly. When an original image is projected and displayed as it is, a projected image is displayed as shown in FIG. Will be distorted. Therefore, the projector 100 detects the arrangement state of the projection screen SC with respect to the projector 100, and executes a trapezoid correction process for correcting the trapezoidal distortion of the original image according to the arrangement state.

  FIG. 4 is a flowchart showing the trapezoidal correction processing procedure executed in projector 100. FIG. 5 is a block diagram showing the internal functions of projector 100 when the keystone correction process is executed. FIG. 5 shows a part of the internal configuration of the projector 100 shown in FIG. 1 rewritten, and the reference numerals of the respective components correspond. This keystone correction process may be started by an instruction from the user via the remote controller 191 (FIG. 1), or may be always executed when the projector 100 is activated.

  In step S10 (FIG. 4), the projector 100 projects a measurement pattern image for measuring the arrangement state of the projection screen SC onto the projection screen SC. As a specific processing procedure in step S10, the CPU 120 transfers the image data representing the measurement pattern image MI stored in advance in the measurement pattern storage unit 171 of the ROM 170, which is a read-only storage unit, to the liquid crystal panel drive unit 132. Send. The liquid crystal panel driving unit 132 causes the liquid crystal panel 130 to form a panel image representing the measurement pattern image MI in the image forming area IF. As a result, the measurement pattern image MI is displayed on the projection screen SC via the projection optical system 150.

  FIG. 6A is an explanatory diagram showing an example of the measurement pattern image MI, and schematically shows the liquid crystal panel 130 in which the measurement pattern image MI is formed in the image forming area IF. 6A shows an intersection OPp between the point where the measurement pattern image MI is formed in the image forming area IF and the optical axis of the projection optical system 150 and the panel surface 130s (hereinafter referred to as “panel optical axis intersection OPp”). 3) is substantially the same as that shown in FIG.

  The measurement pattern image MI has first and second measurement lines LM1 and LM2, which are two straight lines orthogonal to each other. The first measurement line LM1 passes through the panel optical axis intersection OPp and is orthogonal to two opposing long sides of the image forming area IF. On the other hand, the second measurement line LM2 passes through the panel optical axis intersection OPp and is orthogonal to two opposing short sides of the image forming area IF. In the measurement pattern image MI, the intersection of the first and second measurement lines LM1, LM2 and the panel optical axis intersection OPp coincide. By the way, in this projector 100, in order to reduce the distortion of the projected image caused by the optical axis of the projection optical system 150 having an elevation angle with respect to the projection surface, the panel optical axis intersection OPp is previously set from the center of the panel surface 130s. The positions of the projection optical system 150 and the liquid crystal panel 130 are determined so as to be positioned on the lower side.

  FIG. 6B is a schematic diagram showing a state in which the measurement pattern image MI of FIG. 6A is projected and displayed on the projection screen SC. FIG. 6B is the same as FIG. 3B except that a projection image of the measurement pattern image MI (hereinafter referred to as “measurement projection image MIp”) is added. In FIG. 6B, the intersection OPs between the optical axis of the projection optical system 150 and the projection surface of the projection screen SC (hereinafter referred to as “screen optical axis intersection OPs”) is indicated by “x”. .

  The measurement projection image MIp is distorted into a substantially trapezoidal shape on the projection plane. Further, the measurement projection image MIp includes straight lines corresponding to the first and second measurement lines LM1 and LM2 of the measurement pattern image MI. Hereinafter, these straight lines are referred to as “first and second projection measurement lines LM1p, LM2p”. In step S20 (FIG. 4), the imaging screen 180 (FIG. 5) captures the projection screen SC on which the measurement projection image MIp is displayed.

  FIG. 6C is a schematic diagram illustrating a captured image SI captured by the imaging unit 180. In FIG. 6C, the screen optical axis intersection OPs is indicated by “x”. The captured image SI includes the measurement projection image MIp projected on the projection screen SC. Hereinafter, the captured measurement projection image MIp is referred to as “measurement captured image MIs”. The straight lines corresponding to the first and second projection measurement lines LM1p and LM2p included in the measurement captured image MIs are referred to as “first and second imaging measurement lines LM1s and LM2s”, respectively. The imaging unit 180 stores image data representing the captured image SI (hereinafter referred to as “imaging data”) in the captured image memory 182.

  In step S30 (FIG. 4), the CPU 120 reads the imaging data stored in the captured image memory 182 and causes the imaging measurement line detection unit 121 to capture the imaging measurement lines LM1s and LM2s in the coordinate system on the captured image SI (FIG. 6 (FIG. 4). C)) is detected. Specifically, the imaging measurement line detection unit 121 scans the captured image SI in the long side direction and the short side direction, and each of the imaging measurement lines LM1s and LM2s exists on a straight line according to the contrast ratio of the image. At least two or more points are detected, and the barycentric coordinates of the pixels representing each point are obtained. For example, the coordinates of the two end points of each imaging measurement line LM1s, LM2s may be detected.

  The imaging measurement line detection unit 121 calculates inclinations of the imaging measurement lines LM1s and LM2s from the obtained coordinate data, and the projection measurement line detection unit 122 calculates the calculated inclination and at least one of the detected coordinate data. Send to. Hereinafter, a parameter transmitted from the imaging measurement line detection unit 121 to the projection measurement line detection unit 122 is referred to as a “linear parameter”. In step S40, the projection measurement line detection unit 122 obtains the positions and inclinations of the projection measurement lines LM1p and LM2p projected on the projection screen SC in the three-dimensional coordinates using the received linear parameters.

  FIG. 7 illustrates the relationship between the first measurement line LM1 in the measurement pattern image MI, the first projection measurement line LM1p on the projection screen SC, and the first imaging measurement line LM1s in the captured image SI. It is explanatory drawing for doing. FIG. 7 schematically illustrates a state in which the projection optical system 150 projects the measurement pattern image MI onto the projection screen SC and a state in which the imaging unit 180 captures the measurement projection image MIp on the projection screen SC. It shows.

  In the following description, the first measurement line LM1, the first projection measurement line LM1p, and the first measurement line LM2, the second projection measurement line LM2p, and the second imaging measurement line LM2s are also described. This is the same as the imaging measurement line LM1s. Therefore, illustration and description of the second measurement line LM2, the second projection measurement line LM2p, and the second imaging measurement line LM2s are omitted.

  Here, a virtual plane PA (hereinafter referred to as “projection plane PA”) defined by a light beam representing the first measurement line LM1 in the measurement pattern image MI projected by the projection optical system 150 is considered. The projection plane PA can be obtained in advance because the coordinates of the principal point PP of the projection optical system 150 and the expression of the first measurement line LM1 are known.

  By the way, even if the zoom ratio of the projection optical system 150 changes, the projection image of the linear image passing through the optical axis OAp of the projection optical system 150 only expands and contracts in the linear direction. Here, the first measurement line LM1 is a straight line that intersects the optical axis OAp of the projection optical system 150. Therefore, even if the zoom ratio of the projection optical system 150 changes, the light beam representing the first measurement line LM1 only changes in inclination on the projection plane PA around the principal point PP of the projection optical system 150. . Therefore, even when the projection optical system 150 changes the zoom ratio by the zoom lens driving unit 155, the projection plane PA remains unchanged.

  Here, a virtual plane SA (hereinafter referred to as “imaging plane SA”) defined by the principal point PPs of the imaging unit 180 and the first projection measurement line LM1p on the projection screen SC is further considered. The first imaging measurement line LM1s in the captured image SI can be interpreted as an intersection line between the imaging plane SA and the image plane of the captured image SI. Here, the coordinates of the principal point PPs of the imaging unit 180 are known. Therefore, the imaging plane SA can be determined by detecting the first imaging measurement line LM1s in the image plane of the captured image SI. If the imaging plane SA is determined, the first projection measurement line LM1p on the projection screen SC can be obtained as an intersection line between the two planes PA and SA.

Here, the equation of the straight line of the first imaging measurement line LM1s in the coordinate system (uv coordinate system) of the captured image SI is generally given by the following equation (1).
α ₁ u + α ₂ v + α ₃ = 0 (1)
α ₁ , α ₂ , and α ₃ are constants and correspond to linear parameters that the imaging measurement line detection unit 121 transmits to the projection measurement line detection unit 122.

Considering a world coordinate system with the principal point PP of the projection optical system 150 as the origin, the equation of the first imaging measurement line LM1s in the world coordinate system is obtained as the following equation (2) by known coordinate transformation. .
(X-p ₁ ) / q ₁ = (y−p ₂ ) / q ₂ = (z−p ₃ ) / q ₃ (2)
p _{1 to} p ₃ and q _{1 to} q ₃ are constants and are values determined by α ₁ , α ₂ , and α ₃ . Furthermore, if the above equation (2) and the known coordinates x ₀ , y ₀ , z ₀ of the imaging unit 180 are used, the plane equation of the imaging plane SA can be obtained as the following equation (3). .
r ₁ x + r ₂ y + r ₃ z + r ₄ = 0 (3)
Here, r _{1 to} r ₄ are constants and are values determined by x ₀ , y ₀ , z ₀ and α ₁ , α ₂ , α ₃ .

As described above, the projection plane PA projected on the projection screen SC is known, and the plane equation is generally given by the following equation (4).
s ₁ x + s ₂ y + s ₃ z + s ₄ = 0 (4)
Here, s _{1 to} s ₄ are constants. By using the above expressions (3) and (4), a straight line expression representing the first projection measurement line LM1p in the world coordinate system can be obtained as the following expression (5).
(X−m ₁ ) / n ₁ = (ym− ₂ ) / n ₂ = (z−m ₃ ) / n ₃ (5)
m _{1 to} m ₃ are constants indicating the positions of arbitrary points on the straight line, and n _{1 to} n ₃ are constants indicating the slope of the straight line. These constants are values determined by α ₁ , α ₂ , and α ₃ . That is, if the first imaging measurement line LM1s in the coordinate system (uv coordinate system) of the captured image SI can be specified, the first projection measurement line LM1p in the world coordinate system can be uniquely determined.

  The projection measurement line detection unit 122 (FIG. 5) includes a map that associates the linear parameters received from the imaging measurement line detection unit 121 with the expressions of the first and second projection measurement lines LM1p and LM2p. . In step S40 (FIG. 4), the projection measurement line detection unit 122 identifies the first and second projection measurement lines LM1p and LM2p using the map. Further, in step S50, the projection plane detection unit 123 determines the projection plane of the projection screen SC based on the position and inclination through which the first and second projection measurement lines LM1p and LM2p pass. As will be described below, the arrangement state of the projection screen SC can be uniquely specified from the two imaging measurement lines LM1s and LM2s.

  FIG. 8 is an explanatory diagram for further explaining the relationship between the imaging measurement line LM1s and the arrangement state of the projection screen SC. In FIGS. 8A and 8B, the captured image SI is schematically shown. However, for convenience, illustration in the screen other than the imaging measurement line LM1s is omitted. In addition, in the captured images SI of FIGS. 8A and 8B, the screen optical axis intersection point OPs is indicated by “x”.

  FIG. 8A shows the imaging measurement line LM1s in a stepwise manner when the distance between the principal point PP of the projection optical system 150 and the projection screen SC is changed while the inclination angle of the projection screen SC is kept constant. It is the shown schematic diagram. In FIG. 8A, a virtual straight line Loa indicating a locus along which the optical axis of the projection optical system 150 moves is indicated by a broken line. Since the relative positional relationship between the projection optical system 150 and the imaging unit 180 is fixed, the position through which the optical axis of the projection optical system 150 passes in the captured image SI is on one straight line Loa. A point on the straight line Loa is a point located closer to the principal point PP of the projection optical system 150 as the coordinate in the horizontal axis u direction is larger. The screen optical axis intersection OPs is a point on the straight line Loa and also a point on the imaging measurement line LM1s. Therefore, when the distance between the projection screen SC and the projection optical system 150 is increased while the inclination angle of the projection screen SC is kept constant, the display position of the imaging measurement line LM1s in the captured image SI is along the straight line Loa. , And gradually move in the direction opposite to the u-axis direction.

  FIG. 8B is a schematic diagram showing stepwise the imaging measurement line LM1s when the inclination angle of the projection screen SC is changed while keeping the position of the screen optical axis intersection OPs constant. When the inclination angle of the projection screen SC changes, the inclination of the projection measurement line LM1p displayed on the projection surface also changes. Therefore, the inclination of the imaging measurement line LM1s also changes according to the inclination angle of the projection screen SC. However, the change in the inclination of the imaging measurement line LM1s does not reflect the change in the inclination angle in the linear direction of the projection measurement line LM1p. Therefore, the inclination angle of the projection surface of the projection screen SC can be specified by detecting the inclinations of the two imaging measurement lines LM1s and LM2s having different inclinations.

  Thus, the position of the projection screen SC relative to the projection optical system 150 can be specified by obtaining the two imaging measurement lines LM1s and LM2s and obtaining the position of the screen optical axis intersection OPs in the coordinate system of the captured image SI. Further, by specifying the inclinations of the two imaging measurement lines LM1s and LM2s, the inclination angle of the projection screen SC with respect to the optical axis of the projection optical system 150 can be specified.

  In step S60, the projection distance measuring unit 124 calculates the distance (projection distance) between the projection surface of the projection screen SC and the projection optical system 150. Specifically, the intersection between the projection surface of the projection screen SC and the optical axis OAp of the projection optical system 150 is obtained, and the distance between the intersection and the principal point PP of the projection optical system 150 is calculated. In step S70, the zoom lens driving unit 155 drives the focus adjustment motor 157 according to the calculated projection distance to adjust the focus of the projected image.

  In step S80, the projection angle measurement unit 125 calculates the angle (projection angle) of the optical axis OAp of the projection optical system 150 with respect to the projection plane based on the inclination of the projection plane of the projection screen SC determined by the projection plane detection unit 123. To do. In step S90, based on the calculated projection angle, the trapezoidal distortion correction unit 136 of the video processor 134 responds to the digital image signal representing the original image before correction received from the A / D conversion unit 110 according to the projection angle. Execute keystone correction processing. The trapezoidal distortion correction unit 136 transmits a digital image signal representing the corrected original image to the liquid crystal panel drive unit 132.

  As described above, in the projector 100 according to the present embodiment, the measurement line projected on the projection screen SC is photographed, and the measurement line on the photographed image is detected so that the projection image of the measurement line on the projection plane passes. The position and inclination are obtained and the projection plane is specified. That is, according to the projector 100, it is possible to easily and accurately execute the measurement of the projection plane that is the projection target of the projection light. In addition, since the focus and trapezoidal distortion of the projected image can be adjusted using the measurement result, the display image quality of the projector 100 can be improved.

  By the way, in the projector 100, it is also possible to add a zoom ratio detector that detects the position of the zoom lens 152 of the projection optical system 150 and identifies the zoom ratio. However, if the present invention is applied, the projection plane of the projection screen SC can be surveyed without providing the zoom ratio detection unit, and the projector 100 can be reduced in size and weight by the amount that the zoom ratio detection unit can be omitted. Is possible. Further, the projector 100 according to the present embodiment employs an active stereo method that enables triangulation with at least one imaging unit 180. Therefore, the projector 100 can be further reduced in size and weight as compared with a projector that employs a passive stereo method using two or more cameras as an imaging unit.

B. Second embodiment:
FIG. 9 is a flowchart showing a processing procedure of focus adjustment processing executed in the projector 100A as the second embodiment of the present invention. FIG. 9 is substantially the same as FIG. 4 except that the processing steps of steps S50, S80, and S90 are not provided. FIG. 10 is a block diagram similar to FIG. 5 showing the internal functions of the projector 100A when executing the focus adjustment processing. This focus adjustment process may be executed by an instruction from the user via the remote controller 191 or may be executed when the projector is activated. The configuration of the projector 100A according to the second embodiment is substantially the same as that of the projector 100 according to the first embodiment except for the points described below (FIG. 1).

  11A to 11C are explanatory diagrams for explaining a measurement pattern image for focus adjustment processing, a projection image thereof, and a captured image obtained by photographing the projection image. 11A to 11C are the same as FIGS. 6A to 6C except that the second measurement line LM2, the second projection measurement line LM2p, and the second imaging measurement line LM2s are not shown. ).

  In step S10, the projector 100A projects the measurement pattern image MIa (FIG. 11A) on the projection screen SC. In step S20, the imaging unit 180 captures the measurement projection image MIpa (FIG. 11B) projected on the projection screen SC. In step S30, the imaging measurement line detection unit 121 detects the first imaging measurement line LM1s from the captured image SI (FIG. 11C), and calculates a linear parameter of the first imaging measurement line LM1s.

  In step S40, the projection measurement line detection unit 122 determines the position and inclination of the first projection measurement line LM1p on the projection screen SC in the world coordinate system based on the linear parameters received from the imaging measurement line detection unit 121. . In step S50, the projection distance measurement unit 124 obtains the intersection point of the determined first projection measurement line LM1p and the optical axis OAp of the projection optical system 150, and calculates the projection distance. In step S70, the zoom lens driving unit 155 adjusts the focus of the projection optical system 150 according to the calculated projection distance.

  As described above, according to the configuration of the second embodiment, at least one measurement line is projected and displayed on the projection screen SC, the projected image is photographed, and the measurement line in the photographed image is detected. The projection distance can be easily obtained. Therefore, it is possible to easily adjust the focus of the projected image, and the display image quality of the projector 100A can be improved.

C. Third embodiment:
FIG. 12 is an explanatory diagram showing another example of the measurement pattern image projected and displayed by the projector as the third embodiment of the present invention. The configuration of the projector of this embodiment is the same as that of the projector 100A (FIG. 1) of the second embodiment, and a focus adjustment process (FIG. 10) similar to that of the projector 100A is executed.

  FIG. 12 is different from the first measurement line LM1 in that the first and second measurement points MP1 and MP2 are provided and the liquid crystal panel 130 is not shown in FIG. Is almost the same. The first and second measurement points MP1 and MP2 of the measurement pattern image MIb are provided on a center line CL connecting the midpoints of two opposing long sides of the measurement pattern image MIb. The first measurement point MP1 is provided at a position closer to the upper long side toward the paper surface, and the second measurement point MP2 is provided at a position closer to the lower long side toward the paper surface. . When this measurement pattern image MIb is formed on the panel surface of the liquid crystal panel 130 (FIG. 1), the panel optical axis intersection OPp is located on the center line CL.

  The imaging measurement line detection unit 121 of the CPU 120 detects the projected images of the two measurement points MP1 and MP2 from the photographed image, and calculates a linear parameter for a straight line obtained by connecting the barycentric coordinates of the pixels representing the two points. To do. As described above, the measurement pattern image does not need to display the measurement line as a solid line, and includes two or more specific coordinates capable of forming at least one measurement line (including a virtual measurement line). It suffices to include the specific points to be included. Even in such a configuration, the measurement line can be detected by detecting the specific point in the captured image SI, and the position and inclination of the measurement line on the projection screen SC can be detected. . The specific point includes, for example, an intersection of a plurality of straight lines, an end point of the straight line, a corner of a polygon, a center of a circle, and the like. In addition, the position of the specific point is more preferable as the distance between the specific points is longer because a measurement error can be reduced in detection of the imaging measurement line.

D. Variations:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

D1. Modification 1:
In the above embodiment, a part of the configuration realized by hardware may be replaced with software, and conversely, a part of the configuration realized by software may be replaced by hardware. For example, the video processor 134 may execute part or all of the functions of the components 121 to 125 that the CPU 120 has.

D2. Modification 2:
In the first embodiment, the measurement pattern image MI has the first and second measurement lines LM1, LM2. However, the measurement pattern image MI only needs to have at least one measurement line as in the second embodiment in order to measure the projection distance. Further, in order to measure the inclination of the projection plane, it is sufficient to have at least two measurement lines as in the first embodiment. The measurement pattern image MI may further include a plurality of measurement lines and other measurement figures and patterns.

  In addition, the measurement line of the measurement pattern image MI may be a straight line having a different slope from the first and second measurement lines LM1 and LM2 (FIG. 6A) of the first embodiment, and is orthogonal to each other. You don't have to. However, if the measurement line is a straight line extending in the vertical or horizontal direction on the image plane of the measurement pattern image MI, it is preferable because the influence of jaggy due to the dot configuration of the liquid crystal panel 130 is reduced in the imaging measurement line detection process. .

D3. Modification 3:
In the above embodiment, the first and second measurement lines LM1 and LM2 are projected on the projection screen SC so as to intersect the optical axis OAp of the projection optical system 150 on the panel surface of the liquid crystal panel 130. However, the measurement line of the measurement pattern image MI does not have to be projected onto the projection screen SC so as to intersect the optical axis OAp of the projection optical system 150 directly. That is, the measurement pattern image MI may be projected onto the projection screen SC so that the optical axis OAp passes through the straight line on which the measurement line is extended. Even with such a configuration, the projection plane PA can be obtained in advance regardless of the zoom ratio of the projection optical system 150.

  Further, the measurement pattern image MI is projected onto the projection screen SC in a state where the optical axis OAp of the projection optical system 150 does not pass on the measurement line of the measurement pattern image MI or on the straight line obtained by extending the measurement line. It is good as a thing. However, in this case, it is preferable that the projection plane PA corresponding to the zoom ratio of the projection optical system 150 is known.

D4. Modification 4:
In the first embodiment, the projection measurement line detection unit 122 determines the position and inclination of the projection measurement line using a map that uniquely associates the linear parameter with the position and inclination of the projection measurement line. However, the projection measurement line detection unit 122 does not need to use the map, and may calculate the position and inclination of the projection measurement line by using a mathematical formula prepared in advance using linear parameters.

  Further, the projection measurement line detection unit 122 may be omitted. In this case, for example, the projection plane detection unit 123 receives the linear parameter from the imaging measurement line detection unit 121. The arrangement state of the projection screen SC may be determined using a map that uniquely associates the imaging measurement line and the arrangement state of the projection screen SC using the relationship described in FIG. Alternatively, the projection surface detection unit 123 may calculate the arrangement state of the projection screen SC by using a mathematical formula prepared in advance using a linear parameter.

D5. Modification 5:
In the above embodiment, the linear parameters transmitted by the imaging measurement line detection unit 121 are the inclinations of the first and second imaging measurement lines LM1s and LM2s and the coordinate data of at least one end point. However, the straight line parameter may be another parameter as long as it can specify the imaging measurement lines LM1s and LM2s. For example, it may be coordinate data of two end points of the detected measurement line.

D6. Modification 6:
In the above embodiment, the position of the imaging unit 180 is provided at a position fixed with respect to the position of the projection optical system 150. However, the imaging unit 180 may not be provided at a fixed position, and the position may be movable. However, in this case, it is preferable that a position detection unit capable of detecting position information with respect to the projection optical system 150 of the imaging unit 180 is provided.

D7. Modification 7:
In the first embodiment, the trapezoidal distortion correction unit 136 performs keystone correction on the original image according to the measured position and tilt angle of the projection surface of the projection optical system 150. However, the projector 100 may execute processing other than keystone correction using the measured position and tilt angle of the projection plane. In the second embodiment, the zoom lens driving unit 155 adjusts the focus of the projection image according to the measured position of the projection optical system 150. However, the projector 100A may execute a process other than the focus adjustment of the projected image by using the measured position of the projection plane.

FIG. 2 is a schematic block diagram showing an internal configuration of a projector. The schematic front view which shows the external appearance of a projector, and the schematic diagram for demonstrating the projection to the projection screen by a projector. Schematic which shows the panel image of a liquid crystal panel, the projection image displayed on the projection screen, and the picked-up image by an imaging part. The flowchart which shows the process sequence of a trapezoid correction process. The block diagram which shows the function of the projector in a trapezoid correction process. Explanatory drawing for demonstrating the pattern image for a measurement. Explanatory drawing for demonstrating the principle of the zoom ratio measuring method of a projection optical system. Explanatory drawing for demonstrating the relationship between an imaging measurement line and the arrangement state of a projection screen. 10 is a flowchart showing a processing procedure of focus processing in the second embodiment. The block diagram which shows the function of the projector in the focus process in 2nd Example. Explanatory drawing for demonstrating the pattern image for a measurement in 2nd Example. Explanatory drawing for demonstrating the pattern image for a measurement in 3rd Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100,100A ... Projector 100s ... Surface 102 ... Internal bus 105 ... Leg part 110 ... A / D conversion part 120 ... CPU
DESCRIPTION OF SYMBOLS 121 ... Imaging measurement line detection part 122 ... Projection measurement line detection part 123 ... Projection surface detection part 124 ... Projection distance measurement part 125 ... Projection angle measurement part 130 ... Liquid crystal panel 130s ... Panel surface 132 ... Liquid crystal panel drive part 134 ... For images Processor 136 ... Trapezoidal distortion correction unit 140 ... Illumination optical system 150 ... Projection optical system 152 ... Zoom lens 155 ... Zoom lens drive unit 156 ... Zoom adjustment motor 157 ... Focus adjustment motor 160 ... RAM
170 ... ROM
180 ... Image pickup unit 182 ... Captured image memory 190 ... Remote control unit 191 ... Remote control 300 ... Cable CL ... Center line IF ... Image forming area LM1 ... First measurement line LM2 ... Second measurement line LM1p ... First projection measurement Line LM2p ... second projection measurement line LM1s ... first imaging measurement line LM2s ... second imaging measurement line Loa ... straight line MI, MIa, MIb ... measurement pattern image MIp, MIpa ... measurement projection image MIs ... measurement Captured image MP1 ... 1st measurement point MP2 ... 2nd measurement point OAi ... Optical axis (imaging part)
OAp: Optical axis (projection optical system)
OPp ... Panel optical axis intersection OPs ... Screen optical axis intersection PA ... Projection plane PI ... All white projection image PP ... Main point (projection optical system)
PPs ... Principal point (imaging part)
SA ... Shooting plane SC ... Projection screen SI ... Shooting image

Claims (14)

A method for measuring the position or inclination of the projection plane relative to the projection optical system using a projector including a projection optical system that projects image light representing an image onto the projection plane,
(A) the projector, the step of projecting the measurement image a specific point comprises two or more points with known coordinates within the picture image, on the projection plane,
(B) The projector takes a measurement projection image in which the measurement image is projected on the projection plane by an imaging unit whose position relative to the projection optical system is fixed, at a preset zoom ratio. And a process of
(C) Imaging corresponding to a measurement line that is a straight line defined on the projection plane by the projector from at least two specific points projected on the projection plane from an image captured by the imaging unit. Detecting a measurement line;
(D) the projector determining a position or an inclination of the projection plane according to the imaging measurement line;
A method comprising: The method of claim 1, comprising:
The projection optical system includes a zoom mechanism that adjusts a zoom ratio of the projection optical system,
The measurement image is projected onto the projection plane such that the optical axis of the projection optical system passes on the measurement line or an extension line thereof. The method according to claim 1 or 2, comprising:
In the step (c), the projector is a first measurement line that is a straight line defined on the projection plane by at least two specific points projected on the projection plane from an image captured by the imaging unit. And a second measurement line that is defined on the projection plane by at least two specific points projected on the projection plane and that is a straight line having an angle that intersects the first measurement line. Detecting a first imaging measurement line and a second imaging measurement line;
The step (d) is a method in which the projector determines an inclination of the projection plane according to the first and second imaging measurement lines. A method according to any one of claims 1 to 3, comprising
(E) The projector includes a step of executing a predetermined control process for controlling the image light by using the determined position or inclination of the projection plane. The method of claim 4, comprising:
The position of the projection plane includes the position of the intersection of the projection plane and the optical axis of the projection optical system,
The predetermined control process includes a focus process of adjusting a focus of the projection optical system according to a distance between a main point of the projection optical system and the intersection. 6. A method according to claim 4 or 5, wherein
The predetermined control process includes a correction process for correcting a trapezoidal distortion of a projected image projected and displayed on the projection plane. An image processing method using a projection image of a projector including a projection optical system that projects image light representing an image onto a projection plane,
(A) the projector, the step of projecting the measurement image a specific point comprises two or more points with known coordinates within the picture image, on the projection plane by the projection optical system,
(B) The projector takes a measurement projection image in which the measurement image is projected on the projection plane by an imaging unit whose position relative to the projection optical system is fixed, at a preset zoom ratio. And a process of
(C) The projector changes from a captured image captured by the imaging unit to a measurement line that is a straight line defined on the projection plane by at least two specific points projected on the projection plane. Detecting a corresponding imaging measurement line;
; (D) the projector is present on the projection plane, the projection shooting measuring line that corresponds to the measurement line, a first plane defined by the principal point of the imaging unit and the imaging measurement line, Obtaining as a line of intersection with a second plane defined by the principal point of the projection optical system and the measurement line;
A method comprising: The method of claim 7, comprising:
The projection optical system includes a zoom mechanism that adjusts a zoom ratio of the projection optical system,
The method, wherein the measurement image is projected onto the projection plane so that the optical axis of the projection optical system passes on a straight line of the measurement line or an extension line thereof. The method according to claim 7 or 8, comprising:
(E) The projector includes a step of executing a predetermined control process for controlling the image light using the obtained position or inclination of the intersection line. The method of claim 9, comprising:
The position of the projection plane includes the position of the intersection of the projection plane and the optical axis of the projection optical system,
The predetermined control process includes a focus process of adjusting a focus of the projection optical system according to a distance between a main point of the projection optical system and the intersection. The method according to claim 9 or 10, comprising:
The predetermined control process includes a correction process for correcting a trapezoidal distortion of a projected image projected and displayed on the projection plane. A projector that displays image projection by projecting image light representing an image on a projection surface,
A light modulation unit that forms a panel image for generating the image light by modulating the illumination light on a panel surface irradiated with the illumination light, and emits the image light;
A projection optical system for projecting the image light;
A measurement image storage unit for storing measurement image a specific point comprises two or more points with known coordinates within the picture image,
An imaging unit that captures a measurement projection image, which is fixed at a relative position with respect to the projection optical system and the measurement image is projected on the projection plane, at a preset zoom ratio;
A control unit that controls the projection optical system and the light modulation unit;
With
The controller is
Detecting an imaging measurement line corresponding to a measurement line which is a single straight line defined on the projection plane by at least two specific points projected on the projection plane from a photographed image by the imaging section;
In accordance with the imaging measurement line, determining the position or tilt angle of the projection plane,
A projector that corrects a display state of the projection image according to the determined position or inclination angle of the projection surface. The projector according to claim 12, wherein
The control unit includes a first measurement line that is a straight line defined on the projection plane by the two specific points projected on the projection plane from an image captured by the imaging unit, and the projection A first measurement line and a second measurement line which are defined on the projection plane by at least two specific points projected onto a plane and which are straight lines having angles intersecting the first measurement line, respectively. Detecting the imaging measurement line of
The position or inclination angle of the projection plane is determined according to the first and second imaging measurement lines, and the keystone distortion or focus of the projection image is determined according to the determined position or inclination angle of the projection plane. To correct the projector. A program that is executed in a projector including a projection optical system that projects image light representing an image on a projection plane, and that measures the position or tilt of the projection plane with respect to the projection optical system,
A measurement image a specific point comprises two or more points with known coordinates within the picture image, a function of projected on the projection plane,
A function of photographing a measurement projection image in which the measurement image is projected on the projection plane by an imaging unit fixed at a position relative to the projection optical system at a preset magnification;
A function of detecting an imaging measurement line corresponding to a measurement line that is a straight line defined on the projection plane by at least two specific points projected on the projection plane from an image captured by the imaging section; ,
A function of determining the position or inclination of the projection plane according to the imaging measurement line;
A program comprising:

Images