JP2008288630A - Image projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image projector capable of displaying a square image with satisfactory convenience. <P>SOLUTION: A CPU 11 has: a contour detection section 113 for detecting a square shape corresponding to the contour of an image displayed on a screen; a side length calculation section 114 for obtaining upper- and lower-side lengths LU, LD of a square, based on the shape of the square detected by the contour detection section 113; and a first correction section 115 for performing trapezoid correction processing for correcting rays projected from a projection section to form the contour of the image displayed on the screen in a square shape via a trapezoid correction section 154, based on the upper- and lower-side lengths LU, LD obtained by the side length calculation section 114. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image projecting device that includes a light projecting unit that projects a light beam corresponding to an image, and projects the light beam from the light projecting unit to display the image on a substantially planar screen.

  2. Description of the Related Art Conventionally, in an image projection apparatus such as a projector that includes a light projecting unit that projects a light beam corresponding to an image and projects the light beam from the light projecting unit to display the image on a substantially planar screen, Various devices and methods for displaying these images have been proposed.

For example, there is a liquid crystal projector that detects the installation angle of the housing of the liquid crystal projector with an angle detection means such as an acceleration sensor, and corrects the scanning direction and drive shape of the liquid crystal panel with the display screen correction means corresponding to the detected installation angle. It is disclosed (see Patent Document 1).
JP 2003-5278 A

  However, in the above liquid crystal projector, when the housing of the liquid crystal projector is tilted, correction is performed so as to display a square image on the screen. It is difficult to display an image. That is, when the screen is tilted, it is necessary for the user to make corrections so as to display a square image, and the convenience may not be sufficient.

  The present invention has been made in view of the above problems, and an object thereof is to provide an image projection apparatus capable of displaying a square image with good convenience.

  In order to achieve the above object, an image projection apparatus according to claim 1 includes a light projecting unit that projects a light beam corresponding to an image, and projects the light beam from the light projecting unit on a substantially planar screen. An image projection apparatus for displaying an image, wherein a contour detection unit that detects a quadrangle shape corresponding to a contour of an image displayed on a screen, and the quadrangle based on the quadrangle shape detected by the contour detection unit Is displayed on the screen based on the lengths of the upper side and the lower side obtained by the side length calculating means, and the side length calculating means for obtaining the length of the upper side which is the upper side and the lower side which is the lower side. First correction means for performing trapezoidal correction processing for correcting light rays projected from the light projecting unit so that the contour of the image has a square shape.

  An image projection apparatus according to a second aspect is the image projection apparatus according to the first aspect, wherein the contour detection unit includes an imaging sensor that captures an image displayed on a screen, and the imaging sensor is interposed therebetween. And detecting the shape of the rectangle.

  An image projection apparatus according to a third aspect is the image projection apparatus according to the second aspect, wherein the imaging sensor is a CCD sensor.

  The image projection device according to claim 4 is the image projection device according to any one of claims 1 to 3, wherein the first correction unit is configured to reduce the length of the upper side to the length of the lower side. The ratio is obtained, and the keystone correction processing is performed based on the obtained ratio.

  The image projection device according to claim 5 is the image projection device according to any one of claims 1 to 4, wherein an angle formed by a center line of a light beam projected from the light projecting unit with respect to a horizontal line. An inclination angle detecting means for detecting the inclination angle, and an outline of an image displayed on the screen when the screen is arranged in a vertical direction based on the inclination angle detected by the inclination angle detecting means. Second correction means for performing a trapezoidal correction process for correcting the light beam projected from the light projecting unit so that the light beam projected from the light projecting unit has a square shape, and the contour detection means detects the light beam corrected by the second correction means. When projected on the screen, a quadrangular shape corresponding to the contour of the image displayed on the screen is detected.

  The image projection device according to claim 6 is the image projection device according to claim 5, wherein the tilt angle detection unit includes an acceleration sensor that detects a direction of gravitational acceleration, and the acceleration sensor detects the direction through the acceleration sensor. It is characterized by detecting an inclination angle.

  According to the image projecting device of claim 1, a quadrilateral shape corresponding to the contour of the image displayed on the screen is detected, and based on the detected quadrilateral shape, an upper side that is an upper side of the quadrilateral and The length of the lower side, which is the lower side, is obtained. Then, based on the obtained lengths of the upper side and the lower side, a trapezoid correction process is performed to correct the light rays projected from the light projecting unit so that the contour of the image displayed on the screen has a square shape. A square image can be satisfactorily displayed.

  That is, based on the lengths of the upper and lower sides of the quadrangular shape corresponding to the contour of the image displayed on the screen, the light beam projected from the light projecting unit so that the contour of the image displayed on the screen has a square shape Since the keystone correction process is performed to correct the keystone correction process, the keystone correction process is properly performed regardless of whether the housing of the image projection apparatus is tilted or the screen is tilted. A square image can be displayed with good convenience.

  According to the image projecting device of the second aspect, since the quadrangular shape corresponding to the contour of the image displayed on the screen is detected via the imaging sensor that captures the image displayed on the screen, A square shape can be detected with a simple configuration.

  That is, since the quadrilateral shape corresponding to the contour of the image displayed on the screen is detected via the imaging sensor that captures the image displayed on the screen, the contour of the image captured via the imaging sensor is detected. Since the square shape corresponding to the contour of the image can be detected by obtaining the image by image processing or the like, the square shape can be detected with a simple configuration.

  According to the image projecting device of the third aspect, since the imaging sensor is a CCD sensor, a square image can be displayed with a simpler configuration.

  According to the image projecting device of claim 4, the ratio of the length of the upper side of the quadrangular shape corresponding to the contour of the image displayed on the screen to the length of the lower side is obtained, and based on the obtained ratio. Since the keystone correction process is performed, a square image can be easily displayed.

  That is, since the trapezoid correction process is performed based on the ratio of the length of the upper side of the quadrangular shape to the length of the lower side, it is possible to easily and accurately correct the light beam projected from the light projecting unit. A square image can be displayed on the screen.

  According to the image projecting device of the fifth aspect, an inclination angle that is an angle formed by the center line of the light beam projected from the light projecting unit with respect to the horizontal line is detected, and the screen is vertically adjusted based on the detected inclination angle. When arranged in the direction, trapezoid correction processing is performed to correct the light rays projected from the light projecting unit so that the contour of the image displayed on the screen has a square shape. Then, when the corrected light beam is projected on the screen, a quadrilateral shape corresponding to the contour of the image displayed on the screen is detected, and a quadrilateral shape corresponding to the contour of the image displayed on the screen is detected. Based on the lengths of the top and bottom sides of the shape, trapezoidal correction processing is performed to correct the rays projected from the light projecting unit so that the contour of the image displayed on the screen has a square shape. A square image can be displayed.

  That is, when an inclination angle that is an angle formed by the center line of the light beam projected from the light projecting unit with respect to the horizontal line is detected, and the screen is arranged in the vertical direction based on the detected inclination angle, Since trapezoidal correction processing is performed to correct the light beam projected from the light projecting unit so that the contour of the image displayed on the screen has a square shape, the housing of the image projection device is inclined, and the screen is When not tilted, a square image can be displayed by this trapezoidal correction process, so that a square image can be displayed with better convenience.

  In addition, when the screen is arranged in the vertical direction, a trapezoid correction process is performed to correct the light beam projected from the light projecting unit so that the contour of the image displayed on the screen is a square shape. When the projected light beam is projected on the screen, the quadrilateral shape corresponding to the contour of the image displayed on the screen is detected, and the upper side of the quadrilateral shape corresponding to the contour of the image displayed on the screen is detected. Since the trapezoid correction process is performed to correct the light projected from the light projecting unit so that the contour of the image displayed on the screen has a square shape based on the length of the lower side, the housing of the image projector is inclined. In addition, when the screen is tilted, a square image can be displayed by this trapezoidal correction process, so that a square image can be displayed with even more convenience. It is kill the.

  According to the image projecting device of claim 6, an inclination angle which is an angle formed by the center line of the light beam projected from the light projecting unit with respect to the horizontal line is detected via the acceleration sensor for detecting the direction of gravitational acceleration. Therefore, the tilt angle can be detected with a simple configuration.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing an example of a configuration of a projector according to the present invention. The projector 1 (corresponding to an image projection apparatus) includes a CPU 11, a RAM 12, a ROM 13, an operation unit 14, a light projecting unit 15, an acceleration sensor 16, and a CCD sensor 17.

  A CPU (Central Processing Unit) 11 controls the overall operation of the projector 1. A RAM (Random Access Memory) 12 stores information such as image information in a readable and writable manner. A ROM (Read Only Memory) 13 stores a control program for operating the CPU 11 and the like.

  The operation unit 14 receives various operations such as power ON / OFF operations and various settings. The light projecting unit 15 receives an image signal from the outside and projects a light beam to project an image corresponding to the received image signal onto a screen 2 (not shown). Unit 152, signal processing unit 153, trapezoidal correction unit 154, and projection unit 155.

  The input terminal 151 receives an image signal from the outside, and outputs the received image signal to the A / D conversion unit 152. The A / D conversion unit 152 performs A / D conversion processing on the image signal received via the input terminal 151, and the image information generated by the A / D conversion processing is processed by the signal processing unit. 153 is output. The signal processing unit 153 performs enlargement processing (or reduction processing) on the image information output from the A / D conversion unit 152, and converts the image information subjected to the enlargement processing (or reduction processing) into a trapezoid. This is output to the correction unit 154.

  A trapezoid correction unit 154 (corresponding to a part of the first correction unit and a part of the second correction unit) performs a keystone correction process on the image information output from the signal processing unit 153 in accordance with an instruction from the CPU 11. The image information after the keystone correction process is output to the projection unit 155. The projection unit 155 projects a light beam corresponding to the image information subjected to the trapezoid correction process by the trapezoid correction unit 154 toward the screen 2 (not shown).

  The acceleration sensor 16 is composed of a gyro sensor or the like, and detects the direction of gravitational acceleration, and outputs the detected direction of gravitational acceleration to the CPU 11 (an inclination angle detecting unit 111 described later).

  A CCD (Charge Coupled Devices) sensor 17 (corresponding to an imaging sensor) captures an image displayed on a screen 2 (not shown), and the captured image signal is sent to the CPU 11 (a contour detection unit 113 described later). ).

  FIG. 2 is an explanatory diagram showing an example of a trapezoid correction process by the trapezoid correction unit 154 shown in FIG. (A) is a figure which shows the outline 21 of the image displayed on the screen 2 before the trapezoid correction process, (b) is a figure which shows the outline 22 of the image displayed on the screen 2 after the trapezoid correction process. It is. As shown to (a), the outline 21 forms the trapezoid shape whose upper base length LU1 is longer than lower base length LD1 here. As a result of the trapezoid correction process performed by the trapezoid correction unit 154, the contour 22 is corrected to a square shape having a width LD1 of the lower base of the contour 21 shown in FIG.

FIG. 2C is a diagram for explaining the principle of the trapezoid correction process performed by the trapezoid correction unit 154. That is, among the images displayed on the screen 2 before the keystone correction process, the image information of the length LM1 corresponding to the position H1 from the lower end is converted by the keystone correction unit 154 by the magnification α shown in the following equation (1). As a result, it is corrected to a square shape as shown in FIG.
α = (1- (LU1-LD1) / LM1 × (H1 / H0)) (1)

Here, the length LM1 is expressed by the following equation (2).
LM1 = LD1 + (LU1-LD1) × H1 / H0 (2)
Therefore, the following equation (3) is obtained by substituting equation (2) into equation (1).
α = 1− (R−1) / (1+ (R−1) × H1 / H0) (3)
Here, R = LU1 / LD1. That is, the magnification α is given by the ratio R of the upper base length LU1 to the lower base length LD1.

  FIG. 3 is a block diagram showing an example of the functional configuration of the main part of the projector 1 according to the present invention. The CPU 11 of the projector 1 functionally includes an inclination angle detection unit 111, a second correction unit 112, a contour detection unit 113, a side length calculation unit 114, and a first correction unit 115.

  Here, the CPU 11 reads out and executes a control program stored in advance in the ROM 13 or the like shown in FIG. 1 to thereby execute an inclination angle detection unit 111, a second correction unit 112, a contour detection unit 113, a side length calculation unit 114, It functions as a functional unit such as the first correction unit 115.

  Among various data stored in the RAM 12, ROM 13 and the like shown in FIG. 1, data that can be stored in a removable recording medium is, for example, a hard disk drive, optical disk drive, flexible disk drive, silicon disk drive, cassette medium reader In this case, the recording medium is, for example, a hard disk, an optical disk, a flexible disk, a CD (Compact Disk), a DVD (Digital Versatile Disk), a semiconductor memory, or the like.

  The inclination angle detection unit 111 (corresponding to a part of the inclination angle detection means) has an inclination angle that is an angle formed by the center line of the light beam projected from the light projection unit 15 with respect to the horizontal line via the acceleration sensor 16. It is to detect.

  FIG. 4 is an explanatory diagram for explaining an example of a method of detecting the inclination angle θ by the inclination angle detection unit 111. (A) is a figure which shows the case where the projector 1 is mounted horizontally, (b) is the figure which shows the case where the front side of the projector 1 is mounted upward by an angle θ1 with respect to the horizontal. (C) is a diagram showing a case where the front side of the projector 1 is placed downward by an angle θ2 with respect to the horizontal. The light projecting direction is the left side of the figure (the direction indicated by the white arrow).

  As shown in FIGS. 4B and 4C, the direction of gravitational acceleration obtained by the acceleration sensor 16 (thin one-dot chain line in the figure) is relative to the vertical center line of the projector 1 (thick one-dot chain line in the figure). The angles θ1 and θ2 formed by the projectors are respectively inclined angles θ1 and θ2 that are angles formed by the center line of the light beam projected from the light projecting unit 15 (thin one-dot chain line in the figure) with respect to the horizontal line (thick one-dot chain line in the figure). Matches. In other words, the inclination angle detection unit 111 obtains the angle θ formed by the direction of gravity acceleration obtained by the acceleration sensor 16 with respect to the vertical center line of the projector 1 as the inclination angle θ.

  Again, the functional configuration of the CPU 11 will be described with reference to FIG. The second correction unit 112 (corresponding to the second correction unit) displays on the screen 2 when the screen 2 is arranged in the vertical direction based on the inclination angle θ detected by the inclination angle detection unit 111. The trapezoid correction process for correcting the light beam projected from the light projecting unit 15 so as to make the contour of the image formed into a square shape is performed via the trapezoidal correction unit 154.

  The contour detection unit 113 (corresponding to a part of the contour detection means) displays on the screen 2 via the CCD sensor 17 when the light beam corrected by the second correction unit 112 is projected onto the screen 2. A quadrilateral shape corresponding to the contour of the obtained image is detected.

  The side length calculation unit 114 (corresponding to the side length calculation means) is based on the shape of the quadrangle detected by the contour detection unit 113, and the upper side length LU that is the upper side of the quadrangle and the lower side that is the lower side. Is obtained.

  The first correcting unit 115 (corresponding to the first correcting unit) calculates the contour of the image displayed on the screen 2 based on the upper side length LU and the lower side length LD obtained by the side length calculating unit 114. The trapezoid correction process for correcting the light beam projected from the light projecting unit 15 so as to have a square shape is performed via the trapezoid correction unit 154.

  Further, the first correction unit 115 obtains a ratio R (= LU / LD) with respect to the lower side length LD of the side length LU, and based on the obtained ratio R, the keystone correction process is performed via the trapezoid correction unit 154. Is to do. However, the first correction unit 115 determines whether or not the ratio R is equal to or higher than a preset lower limit threshold SHL (for example, 0.9) and equal to or lower than the upper limit threshold SHH (for example, 1.1). However, when it is not less than the lower limit threshold value SHL and not more than the upper limit threshold value SHH, the keystone correction process is not performed.

  As described with reference to FIG. 2, the trapezoidal correction process obtains a ratio R (= LU / LD) with respect to the lower side length LD of the side length LU and is defined by the obtained ratio R. The first correction unit 115 can perform the trapezoidal correction process via the trapezoidal correction unit 154 based on the ratio R (see Expression (3)).

  FIG. 5 is a flowchart showing an example of the operation of the projector 1 (mainly the CPU 11). First, the inclination angle detection unit 111 detects an inclination angle θ, which is an angle formed by the center line of the light beam with respect to the horizontal line (S101). Then, when the screen 2 is arranged in the vertical direction based on the inclination angle θ detected in step S101 by the second correction unit 112, the contour of the image displayed on the screen 2 is made a square shape. Accordingly, a trapezoid correction process for correcting the light beam projected from the light projecting unit 15 is performed (S103). Next, a light beam is projected from the light projecting unit 15 onto the screen 2 by the contour detecting unit 113 (S105).

  Next, a quadrilateral shape corresponding to the contour of the image displayed on the screen 2 is detected by the contour detection unit 113 (S107). Then, the side length calculation unit 114 obtains the length LU of the upper side that is the upper side of the quadrangle and the length LD of the lower side that is the lower side (S109). Next, the first correction unit 115 calculates a ratio R (= LU / LD) to the lower side length LD of the side length LU (S111).

  Next, whether the ratio R calculated in step S111 by the first correction unit 115 is equal to or higher than the lower limit threshold SHL (here, 0.9) and lower than the upper limit threshold SHH (here, 1.1). It is determined whether or not (S113). When it is determined that the ratio R is less than the lower limit threshold SHL (here, 0.9) or greater than the upper limit threshold SHH (here, 1.1) (NO in S113), the first correction unit In step 115, the keystone correction process is performed via the keystone correction unit 154 based on the ratio R obtained in step S111 (S115), and the process ends. When it is determined that the ratio R is equal to or greater than the lower limit threshold value SHL (here, 0.9) and equal to or less than the upper limit threshold value SHH (here, 1.1) (NO in S113), the process ends. Is done.

  6 and 7 are explanatory diagrams showing an example of the trapezoid correction process by the projector 1 (mainly the CPU 11). FIG. 6A shows a case where the projector 1 is placed horizontally and the screen 2 is placed vertically. In this case, without performing the keystone correction process, As shown in FIG. 7A, an image having a square outline 22 is displayed on the screen 2.

  On the other hand, FIG. 6 (b) shows a case where the front side of the projector 1 is placed inclined upward and the screen 2 is placed vertically. In this case, a trapezoidal shape is shown. If correction processing is not performed, as shown in FIG. 7C, a trapezoidal image having an outline 25 and an upper base length LU5 larger than a lower base length LD5 is displayed on the screen 2. Then, the inclination angle θ is detected by the inclination angle detection unit 111, and the trapezoid correction process is performed by the second correction unit 112, whereby the outline 22 of the screen 2 has a square shape as shown in FIG. An image is displayed. In this case, the keystone correction process by the first correction unit 115 is not necessary.

  6C and 6D show a case where the front side of the projector 1 is placed with an inclination upward, and the upper side of the screen 2 is placed with an inclination on the projector 1. In this case, when the trapezoidal correction process is performed by the second correction unit 112, as shown in FIG. 7B, the screen 24 has a contour 24 and the upper base length LU4 is lower. A trapezoidal image smaller than the bottom length LD4 is displayed. Then, the shape of the contour 24 is detected by the contour detection unit 113, the length LU4 of the upper base and the length LD4 of the lower base are obtained by the side length calculation unit 114, and the keystone correction processing is performed by the first correction unit 115. As a result, an image having a square outline 22 is displayed on the screen 2 as shown in FIG.

  In this way, a quadrilateral shape corresponding to the contour of the image displayed on the screen 2 is detected, and based on the detected quadrilateral shape, the upper side length LU, which is the upper side of the quadrangle, and the lower side The length LD of the lower side that is the side is obtained. Then, based on the obtained upper side length LU and lower side length LD, the trapezoidal correction process for correcting the light beam projected from the light projecting unit 15 so that the contour of the image displayed on the screen 2 has a square shape. Therefore, a square image can be displayed with good convenience.

  That is, based on the length LU of the upper side and the length LD of the lower side of the quadrilateral shape corresponding to the contour of the image displayed on the screen 2, the contour of the image displayed on the screen 2 is projected so as to have a square shape. Since the trapezoidal correction process for correcting the light beam projected from the light unit 15 is performed, even when the housing of the projector 1 is tilted or the screen 2 is tilted appropriately Since the keystone correction process is performed, a square image can be displayed with good convenience (see FIGS. 6 and 7).

  Further, since the quadrangle shape corresponding to the contour of the image displayed on the screen 2 is detected via the CCD sensor 17 that captures the image displayed on the screen 2, the quadrangle shape can be formed with a simple configuration. Can be detected.

  That is, since a rectangular shape corresponding to the contour of the image displayed on the screen 2 is detected via the CCD sensor 17 that captures an image displayed on the screen 2, the image is captured via the CCD sensor 17. Since the shape of the quadrangle corresponding to the contour of the image can be detected by obtaining the contour of the image by image processing or the like, the shape of the quadrangle can be detected with a simple configuration.

  Further, a ratio R to the length LD of the lower side of the upper side LU of the quadrilateral shape corresponding to the contour of the image displayed on the screen 2 is obtained, and the trapezoidal correction process is performed based on the obtained ratio R. Therefore, a square image can be easily displayed.

  That is, since the trapezoidal correction process is performed based on the ratio R to the lower side length LD of the upper side length LU of the quadrangular shape, the light beam projected from the light projecting unit 15 can be corrected easily and accurately. Therefore, a square image can be easily displayed.

  In addition, an inclination angle θ that is an angle formed by the center line of the light beam projected from the light projecting unit 15 with respect to the horizontal line is detected, and the screen 2 is arranged in the vertical direction based on the detected inclination angle θ. If so, trapezoidal correction processing is performed to correct the light rays projected from the light projecting unit 15 so that the contour of the image displayed on the screen 2 has a rectangular shape. When the corrected light beam is projected on the screen 2, a quadrilateral shape corresponding to the contour of the image displayed on the screen 2 is detected and corresponds to the contour of the image displayed on the screen 2. Based on the upper side LU and the lower side length LD of the quadrangular shape, a trapezoid correction process is performed to correct the light rays projected from the light projecting unit 15 so that the contour of the image displayed on the screen 2 has a square shape. Therefore, a square image can be displayed with better convenience.

  That is, an inclination angle θ that is an angle formed by the center line of the light beam projected from the light projecting unit 15 with respect to the horizontal line is detected, and the screen 2 is arranged in the vertical direction based on the detected inclination angle θ. In this case, since the trapezoid correction process for correcting the light beam projected from the light projecting unit 15 is performed so that the contour of the image displayed on the screen 2 has a square shape, the casing of the projector 1 is inclined. In addition, when the screen 2 is not tilted, a square image can be displayed by this trapezoidal correction process, so that a square image can be displayed with even better convenience.

  Further, when the screen 2 is arranged in the vertical direction, a trapezoidal correction process is performed to correct the light beam projected from the light projecting unit 15 so that the contour of the image displayed on the screen 2 has a square shape. When the corrected light beam is projected on the screen 2, a quadrilateral shape corresponding to the contour of the image displayed on the screen 2 is detected and corresponds to the contour of the image displayed on the screen 2. Based on the upper side LU and the lower side length LD of the quadrangular shape, a trapezoid correction process is performed to correct the light rays projected from the light projecting unit 15 so that the contour of the image displayed on the screen 2 has a square shape. Therefore, when the casing of the projector 1 is tilted and the screen 2 is tilted, a square image can be displayed by this trapezoidal correction process. It is possible to display a rectangular image in the prime.

  Further, since the inclination angle θ, which is the angle formed by the center line of the light beam projected from the light projecting unit 15 with respect to the horizontal line, is detected via the acceleration sensor 16 that detects the direction of gravitational acceleration, the configuration is simple. The inclination angle θ can be detected.

The present invention can also be applied to the following forms.
(A) In the present embodiment, a case has been described in which the image projection apparatus is a projector 1 that receives an image signal from the outside and projects light rays to display an image corresponding to the received image signal on the screen 2. However, the image projection device may be configured to project a light beam so as to display the image stored therein on the screen 2.

  (B) In this embodiment, the case where the CPU 11 functions as a functional unit such as the tilt angle detection unit 111, the second correction unit 112, the contour detection unit 113, the side length calculation unit 114, and the first correction unit 115 has been described. However, at least one functional unit among the inclination angle detection unit 111, the second correction unit 112, the contour detection unit 113, the side length calculation unit 114, and the first correction unit 115 is configured by hardware such as a circuit. It may be a form.

  (C) In the present embodiment, the second correction unit 112 performs trapezoidal correction processing for the tilt angle θ of the housing of the projector 1, and then the first correction unit 115 performs trapezoidal correction processing for the tilt angle ω of the screen 2. Although the case has been described, the first correction unit 115 may perform a trapezoidal correction process on the inclination angle θ of the casing of the projector 1 and the inclination angle ω of the screen 2. In this case, the process is simplified.

These are the block diagrams which show an example of a structure of the projector which concerns on this invention. These are explanatory drawings which show an example of the trapezoid correction process by the trapezoid correction | amendment part shown in FIG. These are block diagrams showing an example of the functional configuration of the main part of the projector according to the present invention. These are explanatory drawing explaining an example of the detection method of inclination-angle (theta) by an inclination-angle detection part. These are the flowcharts which show an example of operation | movement of a projector (mainly CPU). These are explanatory drawings which show an example of the trapezoid correction process by a projector (mainly CPU). These are figures which show the outline of the image displayed on a screen corresponding to FIG.

Explanation of symbols

1 Projector 11 CPU
111 Inclination angle detection unit (part of inclination angle detection means)
112 2nd correction | amendment part (2nd correction means)
113 Contour detection unit (part of contour detection means)
114 Side length calculation unit (side length calculation means)
115 1st correction | amendment part (1st correction means)
15 Light Emitting Unit 16 Acceleration Sensor (Part of Tilt Angle Detection Unit)
17 CCD sensor (part of contour detection means)
2 screens

Claims (6)

An image projection apparatus comprising a light projecting unit that projects a light beam corresponding to an image, projecting the light beam from the light projecting unit, and displaying the image on a substantially planar screen,
Contour detecting means for detecting a quadrilateral shape corresponding to the contour of the image displayed on the screen;
Based on the shape of the quadrangle detected by the contour detection unit, a side length calculation unit that obtains the length of the upper side that is the upper side and the lower side that is the lower side of the quadrangle;
Based on the lengths of the upper side and the lower side obtained by the side length calculation means, a trapezoidal correction process is performed to correct the light rays projected from the light projecting unit so that the contour of the image displayed on the screen has a square shape. First correction means;
An image projection apparatus comprising:   The image projection apparatus according to claim 1, wherein the contour detection unit includes an imaging sensor that captures an image displayed on a screen, and detects the shape of the square via the imaging sensor.   The image projection apparatus according to claim 2, wherein the imaging sensor is a CCD sensor.   The first correction means obtains a ratio of the length of the upper side to the length of the lower side, and performs trapezoidal correction processing based on the obtained ratio. The image projection apparatus described in 1. An inclination angle detecting means for detecting an inclination angle which is an angle formed by a center line of a light beam projected from the light projecting unit with respect to a horizontal line;
Based on the tilt angle detected by the tilt angle detecting means, when the screen is arranged in the vertical direction, the image projected on the screen is projected from the light projecting unit so as to have a rectangular shape. Second correction means for performing a trapezoidal correction process for correcting the light beam,
With
The contour detection unit detects a quadrangular shape corresponding to the contour of an image displayed on the screen when the light beam corrected by the second correction unit is projected on the screen. The image projection apparatus in any one of Claims 1-4.   The image projection apparatus according to claim 5, wherein the tilt angle detection unit includes an acceleration sensor that detects a direction of gravitational acceleration, and detects the tilt angle via the acceleration sensor.

Images