JP2005159427A - Projector with automatic trapezoidal distortion correcting means - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projector with an automatic trapezoidal distortion correcting means which can measure the inclination angle of a screen with respect to the projection optical axis of the projector for trapezoidal distortion correction of a video image, irrespective of the type of screen. <P>SOLUTION: A light of uniform luminance is projected from the projection lens 21 of a projection apparatus 20 on the screen, an optical intensity measuring sensors 52 at five points aligned in the inside receives a reflection light through a single pinhole 51 provided on the front wall surface of the projector 10. A reception light intensity analysis inclination angle calculator 53 calculates a secondary curve obtained by connecting ends of bars of optical intensity measurement values at respective positions in a bar graph from optical intensity measurement results of three points selected in a strong order, acquires the distance between a position on a datum line 29 on the top point of the secondary curve and a point of the vertical upper portion of the projection optical axis 27 of the datum line 29, and calculates an inclination angle on the datum surface from the previously set correspondence relation between the distance and the inclination angle and outputs the calculated angle to an image control unit 23. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a projector, and more particularly to a projector having an automatic trapezoidal distortion correcting means for automatically correcting a trapezoidal distortion of an image by calculating an inclination angle between a projection optical axis of a projection device of a projector to be used and a screen.

  With the rapid development of liquid crystal technology and DLP (registered trademark) (digital light processing) technology, miniaturization and high performance of projectors have expanded the use of projectors for image projection, and display televisions at home. It is also attracting attention as a large-sized display device that can replace this.

  However, unlike a display-type television, a projector has a problem that a video image is distorted due to the relative relationship between the projection optical axis of the projector and the screen because the screen is a screen or a wall. Disclosed is a method for adjusting the angle of a liquid crystal display unit according to an angle calculated from both detection results, having a detecting means for detecting an installation angle of a liquid crystal projector and a distance detecting means for detecting a distance between the liquid crystal projector and a projection target. (See Patent Document 1). In this case, it is necessary to mechanically adjust the angle of the liquid crystal display unit.

On the other hand, when the vertical and horizontal inclinations of the screen with respect to the projection optical axis of the projector are known, a technique for projecting a distortion-free image on the screen by converting the coordinates of the frame memory of the projector has been put into practical use. Therefore, in order to measure the vertical tilt that is likely to cause distortion, the vertical tilt of the projector is detected by the gravity sensor on the assumption that the screen is installed vertically, and distortion correction corresponding to the tilt is performed. Projectors have already been disclosed and sold (see Patent Document 2).
Japanese Patent Laid-Open No. 9-281597 JP 2003-5278 A

  However, the method described in Patent Document 2 is based on the premise that the screen is installed vertically, and when the screen is not installed vertically or is inclined in the horizontal direction with respect to the projection optical axis of the projector. There is a problem that accurate distortion correction cannot be performed. The inventor of the present invention can accurately measure tilt angles in a vertical direction and a horizontal direction with respect to a projection optical axis of a screen projector using a laser pointer and a digital camera having an image sensor to correct image distortion. Was filed in Japanese Patent Application No. 2003-143501. Although the tilt angle measuring device of Japanese Patent Application No. 2003-143501 is very excellent as a means for accurately obtaining the angle of the projector with respect to the screen, the cost is high because a digital camera having an image sensor is used as its constituent equipment. It has become.

  Furthermore, with the expansion of the use of projectors, there is an increasing demand for keystone correction to be automatically performed at a low cost.

  A reference plane for projecting uniform luminance light from the projection lens of the projection device onto the screen, and measuring the tilt angle inside the housing via a single light guide provided on the front surface of the projector housing for the reflected light from the screen Light received by three light intensity measurement sensors provided on a reference line parallel to the light, and measured from the light intensity measurement results of the three light intensity measurement sensors when the reference line is the horizontal axis and the light intensity is the vertical axis. Calculate the approximate quadratic curve connecting the tips of the bar graphs of the measured light intensity values at each position, and include the position on the horizontal axis of the vertex of the quadratic curve and the projection optical axis of the reference line, and a plane perpendicular to the reference plane A method to calculate the tilt angle on the reference plane and control the output video of the display unit from the preset correlation between the distance and the tilt angle is determined. Has been.

  This method has been put into practical use as a method that can automatically correct trapezoidal distortion at a low cost, but for high gain screens such as aluminum vapor deposition screens, the apex of the approximate quadratic curve is measured when the tilt angle is large. In some cases, the angle of the projection optical axis with respect to the screen cannot be obtained.

  FIG. 10 is a schematic diagram showing a state of reflected light of uniform brightness light projected on a screen from a projection apparatus of a conventional example, (a) is a state where the tilt angle between the projection optical axis and the screen is 90 °, (B) is the case of the first inclination angle, and (c) is the case of the second inclination angle smaller than the first inclination angle.

  FIG. 11 shows the position of the light intensity measurement sensor with the horizontal axis of the conventional example shown as a reference line, and the tip of the bar graph of the light intensity measurement value when the vertical axis is the light intensity measurement value measured by the light intensity measurement sensor. It is a schematic diagram showing a connecting quadratic curve, (a) is a state in which the tilt angle between the projection optical axis and the screen is 90 °, (b) is a case of the first tilt angle, (c) is This is the case of the second inclination angle, and (d) is the case of the second inclination angle and the screen is a high gain screen.

  The uniform luminance light projected from the projection lens 121 of the projector is reflected by the screen 70 and passes through a pinhole 151 provided above the projection lens 121, so that three light intensity measurement sensors 152L provided in a row in the projector. , 152C, and 152R.

  In the case of a normal screen, if the projection optical axis 37 is orthogonal to the screen 70 as shown in FIG. 10A, the light intensity of the center light intensity measurement sensor 152C is the strongest, and the left and right light intensity measurement sensors. Assuming that 152L and 152R are arranged symmetrically with respect to the center light intensity measurement sensor 152C, the light intensity measurement values of the left and right light intensity measurement sensors 152L and 152R are the same and are the same as those of the center light intensity measurement sensor 152C. Also become weaker. When the reference line 29 is displayed on the horizontal axis and each light intensity measurement value is displayed on the vertical axis, FIG. 11A is obtained.

  As shown in FIG. 10B, the projection optical axis 37 intersects the screen 70 at the first angle α, and the reflected light 32 connecting the left light intensity measurement sensor 152L and the pinhole 151 and the screen 70 are assumed. If it is assumed that the angle formed between the reflected light 32 connecting the light intensity measurement sensor 152C in the center and the pinhole 151 and the angle between the screen 70 and the light intensity measurement value of the center light intensity measurement sensor 152C and the left light are the same. The light intensity measurement value of the intensity measurement sensor 152L becomes the same, and the light intensity measurement value of the right light intensity measurement sensor 152R becomes weaker. When the reference line 29 is displayed on the horizontal axis and each light intensity measurement value is displayed on the vertical axis, FIG. 11B is obtained.

  As shown in FIG. 10C, the projection optical axis 37 intersects the screen 70 at a second angle β smaller than the first angle α, and the main reflected light 33 from the screen 70 is passed to the left light intensity measurement sensor 152L. , The light intensity measurement value of the left light intensity measurement sensor 152L is the strongest, the light intensity measurement value of the center light intensity measurement sensor 152C is weaker, and the right light intensity measurement sensor 152R. The measured light intensity is even weaker than that. When the reference line 29 is displayed on the horizontal axis and each light intensity measurement value is displayed on the vertical axis, FIG. 11C is obtained.

  From the light intensity measurement results of the light intensity measurement sensors 152 at the center and at both ends, for example, when the reference line 29 is set on the horizontal axis and the light intensity measurement value is set on the vertical axis as shown in FIG. When the quadratic curve 181 connecting the tips of the bar graphs of the measured light intensity values at the respective positions is calculated, the position on the horizontal axis of the vertex 182 of the quadratic curve 181 is obtained, and the horizontal axis of the vertex 182, that is, the reference The inclination angle between each screen and the projection optical axis can be calculated from the position on the line 29.

  However, when the screen is a high gain screen such as an aluminum vapor deposition screen, when the inclination angle between the screen and the projection optical axis is small as shown in FIGS. 10A and 10B, it is not much different from a normal screen. However, when the tilt angle is large as shown in FIG. 10 (c), the actual light intensity 183 becomes a value indicated by a dotted line as shown in FIG. 10 (d). The vertex 182 of the next curve 181 cannot be obtained, and the inclination angle with respect to the projection optical axis of the projector with respect to the screen cannot be obtained.

  An object of the present invention is to provide an automatic trapezoidal distortion correction means that can measure the tilt angle of the screen in the vertical direction and / or the horizontal direction with respect to the projection optical axis of the projector at a low cost for correcting the trapezoidal distortion of the image regardless of the type of the screen. It is to provide a projector provided.

A projector provided with the automatic trapezoidal distortion correcting means of the present invention,
A projection device having a display unit and a projection lens and projecting an image on a screen, an inclination angle measuring device for calculating an inclination angle of the projection optical axis of the projection device with respect to the screen, and an output of the display unit according to the calculated inclination angle The projector includes an automatic trapezoidal distortion correction unit including an image control unit that corrects the trapezoidal distortion of the video projected on the screen by controlling the video.

The projection device has uniform luminance light output means for projecting uniform luminance light, which is light of uniform luminance, from the projection lens of the projection device onto the screen,
The tilt angle measuring device is provided on the housing wall surface of the projector with a predetermined interval in a direction perpendicular to the projection optical axis with respect to a reference plane including the projection optical axis, which is a plane on which the tilt angle is calculated. And a plane parallel to the reference plane and a plane perpendicular to the projection optical axis so as to receive the reflected light from the screen of uniform luminance light passing through the light guide in the housing of the projector. From the light intensity measurement results of at least four light intensity measurement sensors that are provided in a line on a reference line that is an intersection of the light and that measures the light intensity of the received reflected light, and at least four light intensity measurement sensors, When three light intensity measurement values are selected in descending order of the light intensity measurement values, the position on the reference line of the selected three light intensity measurement values is taken as the horizontal axis, and the light intensity at that position is taken as the vertical axis. , Near the tip of the bar graph of the light intensity measured at each position Calculate a quadratic curve, find the distance between the position of the vertex of the quadratic curve on the reference line and the intersection of the reference line and the plane that includes the projection optical axis and is perpendicular to the reference plane, and the distance and tilt angle And a received light intensity analysis inclination angle calculation unit that calculates an inclination angle on the reference plane and outputs the inclination angle to the image control unit from a preset correlation between and.

  The reference plane may be a horizontal plane, the light guide unit may be arranged in a direction perpendicular to the projection optical axis, and the tilt angle measuring device may project the projection optical axis on the vertical plane including the projection optical axis of the projector. A vertical inclination sensor that detects the inclination angle of the vertical direction, and the inclination angle on the vertical plane detected by the vertical inclination sensor and the inclination angle on the horizontal plane calculated by using the light intensity measurement sensor are combined and displayed. The output video of the unit may be controlled.

  The reference plane may be a vertical plane, the light guide may be arranged horizontally from the projection optical axis, the reference plane is a horizontal and vertical plane, and the light guide is on the projection optical axis. On the other hand, they may be arranged in the vertical direction and the horizontal direction, and a light intensity measurement sensor may be provided for each.

  The uniform luminance light output means is a light source and a light valve of the display unit of the projection device, and the uniform luminance light may be projection image light or infrared light.

  The light source of the uniform luminance light may be a high-pressure mercury lamp or LED, the light intensity measurement sensor may be a phototransistor, and the light guide unit is a pinhole provided on the wall surface of the projection device. Or an optical lens.

  Since the present invention can easily calculate the vertical and / or horizontal inclination angles between the projection optical axis of the projection apparatus and the screen regardless of the type of the screen, the arrangement of the display unit on the pixels of the image can be moved. Thus, the trapezoidal distortion can be corrected and the image projected on the screen can be corrected to the correct state.

  This is because light of uniform brightness is projected onto the screen from the projection lens of the projection device, and is placed in front of the projector at a predetermined interval from the projection optical axis in a direction perpendicular to the reference plane including the projection optical axis whose inclination angle is measured. The reflected light is received by at least four light intensity measurement sensors arranged in a line on a reference line parallel to the reference plane inside the projector through one light guide provided on the wall surface, and the inclination angle calculation of the received light intensity is calculated. 3 parts were selected in order of strong light intensity measurement values, and each of the measured light intensity measurement results from the light intensity measurement results of the three light intensity measurement sensors with the reference line as the horizontal axis and the light intensity measurement value as the vertical axis Calculate the approximate quadratic curve connecting the tips of the bar graphs of the measured light intensity at the position, and the intersection of the position of the vertex of the quadratic curve on the reference line and the plane that includes the projected optical axis of the reference line and is perpendicular to the reference plane Find the distance between and the distance and slope This is because the display unit can be controlled so as to eliminate the distortion of the screen by calculating the tilt angle on the reference plane from the preset correlation with the degree, and in order of increasing the light intensity measurement value, there are three places. This is because the error between the vertex of the quadratic curve and the position where the light intensity is the strongest can be reduced regardless of the inclination angle and the screen type.

  In addition, the tilt angle measuring device of the present invention can be configured at low cost. This is because the measurement can be performed by using four or more light intensity measurement sensors at low cost without using a high-cost digital camera having an image sensor.

  Next, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic block diagram of a projector equipped with an automatic trapezoidal distortion correction unit according to the first embodiment of the present invention. FIG. 2 shows an automatic trapezoidal distortion correction unit according to the first embodiment of the present invention. FIG. 3A is a front view, FIG. 3B is a side view, FIG. 3C is a top view, and FIG. 3 is a reflected light of light having a uniform luminance projected from the projector onto the screen. (A) is a state in which the tilt angle between the projection optical axis and the screen is 90 °, (b) is the first tilt angle α, and (c) is from the first tilt angle. (D) is the distribution of light intensity depending on the incident angle of the light beam on the screen and the reflection angle of the reflected light beam, and FIG. 4 shows the horizontal axis when the screen is a high gain screen. The light intensity measurement sensor position with the reference line as the reference line and the vertical axis the light intensity measurement sensor It is a schematic diagram which shows the quadratic curve which connects the front-end | tip of the bar graph of the selected light intensity measurement value when it is set as the light intensity measurement value which S measured, (a) is 90 degrees of inclination angles of a projection optical axis and a screen. The state of °, (b) is the case of the first inclination angle, and (c) is the case of the second inclination angle. Here, the light guide is described as a pinhole, but an optical lens may be used as described later.

  As shown in FIG. 1, the projector 10 performs the overall operation of the projection device 20 having the projection lens 21 and the display unit 22, the image control unit 23 that controls the image of the display unit 22, and the tilt angle measuring device 30. A central processing unit 60 that controls the image, and the distortion of the image on the screen 70 is corrected by controlling the output image of the display unit 22 according to the inclination angle calculated by the inclination angle measuring device 30. Image distortion correction is automatically performed by the central processing unit 60 in a predetermined procedure.

  The projection device 20 has uniform luminance light output means for projecting uniform luminance light, which is light of uniform luminance such that the maximum luminance is white from the projection lens 21 when measuring the tilt angle, onto the screen 70 as an image. The uniform luminance light is projected as uniform luminance light by controlling the output light of a high-pressure mercury lamp, which is a normal light source, with a light valve, but the light source may be an LED (light emitting diode). The uniform luminance light may be an infrared ray obtained by cutting visible light. In this case, the light intensity barycentric position can be measured without increasing the luminance of the screen surface itself.

  The tilt angle measuring device 30 includes a pinhole 51 provided on the front surface of the casing of the projector 10 at a predetermined interval in a vertical direction from a reference plane 28 including the projection optical axis 27 that is a plane on which the tilt angle is calculated. A reference line which is an intersection line with a plane parallel to the reference plane 28 and perpendicular to the projection optical axis 27 inside the projector 10 so as to receive the reflected light 32 of the uniform luminance light from the screen 70 passing through the pinhole 51. Light intensity measurement sensors 52 (52C, 52R1, 52R2, 52L1) provided in a line on the line 29 and disposed at the center vertically above the projection optical axis 27 with respect to the reference plane 28 and at two locations on both sides. , 52L2) and a received light intensity analysis inclination angle calculation unit 53.

  The received light intensity analysis inclination angle calculation unit 53 selects three light intensity measurement values in the descending order of the light intensity measurement values from the light intensity measurement results of the five light intensity measurement sensors 52, and selects the selected three light beams. For the light intensity measurement sensor 52 of the intensity measurement value, an approximate quadratic curve 81 connecting the tips of the bar graphs of the light intensity measurement values at each position measured with the reference line 29 as the horizontal axis and the light intensity measurement value as the vertical axis. And calculating the distance between the position of the apex 82 of the quadratic curve 81 on the reference line 29 and the intersection of the plane including the projection optical axis 27 on the reference line 29 and perpendicular to the reference plane 28, Based on a predetermined correlation between the distance and the tilt angle, the tilt angle on the reference plane is calculated to control the output video of the display unit 22 so as to eliminate screen distortion.

  The angle between the straight line connecting the position of the apex 82 of the quadratic curve 81 on the reference line 29 and the pinhole 51 and the straight line connecting the pinhole 51 perpendicular to the reference line is the screen 70 on the reference plane 28. Therefore, the tilt angle may be calculated by calculation, or a table may be created based on actual measurement values and the tilt angle calculated by referring to the table. Good. For example, a phototransistor is used as the light intensity measurement sensor 52.

  The present invention can be applied to the projector 10 regardless of whether it is a liquid crystal projector or a DLP (registered trademark) (digital light processing) type projector. The display unit 22 in the case of a liquid crystal projector is a liquid crystal display unit. The display unit 22 includes a DMD (digital micromirror device) display unit, a color wheel, and a light source.

  As shown in FIG. 2, the pinhole 51 is arranged at a predetermined interval from the projection optical axis 27 in a direction perpendicular to the reference plane 28 including the projection optical axis 27 that is a plane whose inclination angle is calculated. The light intensity measurement sensor 52 provided on the front wall surface of the housing receives the reflected light 32 from the screen 70 of the high-intensity projection light 31 that passes through the pinhole 51 inside the housing of the projector 10. , Provided in a line on a reference line 29 that is a line of intersection between a plane parallel to the reference plane 28 and a plane perpendicular to the projection optical axis 27, a center vertically above the projection optical axis 27 with respect to the reference plane 28, and It is arranged at a total of five locations, two on each of the left and right sides. In this embodiment, the description will be made assuming that the number of the light intensity measurement sensors 52 is five, but it is sufficient that the number is four or more. As the number is increased, the accuracy is improved but the cost is also increased. Further, the light intensity measurement sensor 52 only needs to have a fixed position on the reference line 29.

  As shown on the left side of FIG. 3D, when the direction of the projection light 31 and the screen 70 are orthogonal to each other, the strongest reflected light 32 is obtained in the incident direction, and the light intensity decreases corresponding to the reflection angle. . As shown on the right side of FIG. 3D, if the direction of the projection light 31 and the screen 70 are inclined, the screen 70 is the strongest in the direction symmetrical to the projection light 31 with respect to the direction perpendicular to the screen 70. The main reflected light 33 is obtained, and the light intensity decreases corresponding to the deviation from this direction. Therefore, if the angle between the direction of the optical axis 27 and the direction of the main reflected light 33 can be specified, this angle becomes the inclination angle between the plane perpendicular to the optical axis 27 on the reference plane 28 and the screen 70.

  Therefore, if the projection optical axis 37 is orthogonal to the screen 70 as shown in FIG. 3A, the light intensity measurement value of the center light intensity measurement sensor 52C is the strongest, and the left light intensity measurement sensor 52L1, If the light intensity measurement sensor 52R1 and the right light intensity measurement sensor 52R1, 52R2 are arranged symmetrically about the center light intensity measurement sensor 52C, the light intensity measurement values of the left and right light intensity measurement sensors 52L1, 52R1 and 52L2, The light intensity measurement values of 52R2 are the same values, and become weaker as they move away from the central light intensity measurement sensor 52C. When the screen is a high gain screen, when the reference line 29 is displayed on the horizontal axis and the respective light intensity measurement values are displayed on the vertical axis, FIG. 4A is obtained. When the light intensity measurement values are selected in the descending order, 52C, 52L2, and 52R2 indicated by solid lines are obtained, and the quadratic curve 81 is a quadratic curve that passes through these three light intensity measurement values. Here, the dotted line is the actual light intensity 83 on the reference line 29, but it coincides with the quadratic curve 81 except for both ends, and the position of the vertex 82 also coincides.

  As shown in FIG. 3B, the projection optical axis 37 intersects the screen 70 at the first angle α, and it is assumed that the reflected light 32 connecting the left end light intensity measurement sensor 52 </ b> L <b> 1 and the pinhole 51 and the screen 70. Assuming that the angle formed between the reflected light 32 connecting the pinhole 51 and the central light intensity measurement sensor 52C and the screen 70 is the same, the light intensity measurement value of the central light intensity measurement sensor 52C and the light at the left end The light intensity measurement value of the intensity measurement sensor 52L1 becomes the same, and the light intensity measurement value of the light intensity measurement sensor 52L2 becomes stronger than that. The light intensity measurement values of the right light intensity measurement sensors 52R2 and R1 become weaker in order. When the screen is a high gain screen, when the reference line 29 is displayed on the horizontal axis and the respective light intensity measurement values are displayed on the vertical axis, FIG. 4B is obtained. If the light intensity measurement values are selected in descending order, the light intensity measurement sensors 52L2, 52C, and 52L1 are obtained, and the quadratic curve 81 is a quadratic curve that passes through these three points. Here, the dotted line is the actual light intensity on the reference line 29, but it coincides with the quadratic curve 81 except for the right side, and the position of the vertex 82 also coincides.

  As shown in FIG. 3C, the projection optical axis 37 intersects the screen 70 at a second angle β smaller than the first angle α, and the main reflected light 33 from the screen 70 is passed to the light intensity measurement sensor 52L1 at the left end. , The light intensity measurement value of the left end light intensity measurement sensor 52L1 is the strongest, the light intensity measurement sensor 52L2 follows, and the light intensity measurement value of the central light intensity measurement sensor 52C is higher than that. The light intensity measurement values of the right light intensity measurement sensors 52R2 and 52R1 are weaker in order. When the screen is a high gain screen, when the reference line 29 is displayed on the horizontal axis and the respective light intensity measurement values are displayed on the vertical axis, FIG. 4C is obtained. Here, when the light intensity measurement values are selected in descending order, 52L2, 52L1, and 52C are obtained, and the quadratic curve 81 is a quadratic curve that passes through these three points. Here, the dotted line is the actual light intensity on the reference line 29, but is deviated from the quadratic curve 81 on the right side from the center, which is the cause of the problem in the conventional example. Therefore, the correct vertex 82, that is, the strongest point of the actual light intensity 83 can be obtained even when the slope is large on the high gain screen.

  The received light intensity analysis inclination angle calculation unit 53 calculates the reference line 29 from the light intensity measurement results of the three light intensity measurement sensors 52 selected in descending order of the light intensity measurement values, for example, as shown in FIG. A quadratic curve 81 connecting the tips of the bar graphs of the measured light intensity values at the respective positions when the horizontal axis is the light intensity measurement value and the vertical axis is the vertical axis is calculated. Find the position of. As shown in FIG. 3, the reflected light 32 passing through the pinhole 51 coincides with the projected light 31, that is, the reflected light 32 becomes maximum when the projected light 31 and the screen 70 are orthogonal to each other. Accordingly, since the reflected light 32 that connects the position of the apex 82 of the quadratic curve 81, that is, the position on the reference line 29, and the pinhole 51, that is, the projection light 31 and the screen 70 are orthogonal, the horizontal axis, that is, the reference The angle formed by the straight line connecting the position of the vertex 82 on the line 29 and the pinhole 51 and the straight line connecting the pinhole 51 perpendicular to the reference line 29 is perpendicular to the screen 70 and the projection optical axis 27 on the reference plane 28. The tilt angle is approximated to the tilt angle with a smooth surface, or the tilt angle is calculated by calculation, or a table is created based on the actually measured values and the tilt angle is calculated with reference to the table. Control the output video.

  FIG. 5 is a schematic flowchart showing a process of correcting the output image of the display unit 22 from the light intensity measurement values of the plurality of light intensity measurement sensors 52. The received light intensity analysis inclination angle calculation unit 53 selects three points in descending order of the light intensity measurement values from the light intensity measurement values of the five light intensity measurement sensors 52 (step S1), and the selected three light intensity measurement values. Is generated (step S2), and the deviation between the position of the central light intensity measurement sensor 52C, that is, the position above the projection optical axis 27 and the position of the apex of the quadratic curve is calculated (step S3). Based on this, an inclination angle between the optical axis of the projection device 20 and the screen 70 is generated by calculation or table reference (step S4), and the image control unit 23 generates an LSI control parameter in response to the generated inclination angle ( In step S5), by controlling the projector image processing LSI (step S6), the input video 24 is modified to become an output video 25 on the display unit 22. When the output video 25 is projected onto the screen 70, it becomes a video similar to the input video 24. In this method, it is desirable that the screen 70 is irradiated with uniform brightness. However, since the center portion tends to be irradiated more brightly in practice, in step S4 including the correction, the angle is calculated by calculation. It is also desirable to calculate the angle using a table.

  In the description so far, the horizontal inclination angle has been measured, but the vertical inclination is obtained by rotating the positions of the pinhole 51 and the light intensity measurement sensor 52 about the projection optical axis 27 by 90 °. It is possible to measure the angle.

  Although the light guide is described as a pinhole here, the same measurement can be performed even with an optical lens. FIG. 6 is a schematic diagram showing a light incident state of the reflected light 32 from the screen 70 to the light intensity measurement sensor 52 when the convex lens 56 is used as the light guide unit. Even when the convex lens 56 is used, the reflected light 32 from the screen 70 is input to the light intensity measurement sensor 52 in the same manner as the reflected light 32 from the screen 70 when the pinhole 51 is used.

  Next, a second embodiment of the present invention will be described. FIG. 7 is a schematic block diagram of a projector provided with automatic trapezoidal distortion correcting means according to the second embodiment of the present invention. In the second embodiment, the inclination angle measuring device 30 is an inclination sensor (G sensor) using an acceleration detection element that is also used for centering of machine installation, and the inclination angle with respect to the direction of gravity is set. Since the configuration and operation are the same as those of the first embodiment except that a vertical inclination sensor 54 that precisely measures and outputs numerical data is provided, the same components are denoted by the same reference numerals and the same parts are designated. Description is omitted.

  The vertical inclination angle detected by the vertical inclination sensor 54 is input to the received light intensity analysis inclination angle calculation section 53, and the received light intensity analysis inclination angle calculation section 53 uses the light intensity measurement value measured by the light intensity measurement sensor 52 to determine the horizontal angle. In addition to calculating the tilt angle in the direction, the tilt angle in the vertical direction detected by the vertical tilt sensor 54 is output to the image control unit 23, and the image control unit 23 takes into account the tilt in the horizontal and vertical directions. Generate control parameters. In this case, the same processing is performed as described in the first embodiment even if the light receiving unit is a convex lens 56 instead of the pinhole 51.

  Next, a third embodiment of the present invention will be described. FIG. 8 is a schematic block diagram of a projector provided with the automatic trapezoidal distortion correcting means of the third embodiment of the present invention, and FIG. 9 shows the automatic trapezoidal distortion correcting means of the third embodiment of the present invention. It is a schematic diagram of the projector provided, (a) is a front view, (b) is a side view, (c) is a top view.

  In the third embodiment, in addition to the pinhole 51 and the five light intensity measurement sensors 52 that are only used for measuring the tilt angle in the horizontal direction in the first embodiment, it is used for measuring the tilt angle in the vertical direction. Since the configuration and the operation are the same as those of the first embodiment except that the pinhole 51 ′ and the five light intensity measurement sensors 52 ′ are provided and connected to the received light intensity analysis inclination angle calculation unit 53, the same. Constituent elements are denoted by the same reference numerals, and descriptions of the same parts are omitted.

  The light intensity measurement values measured by the five light intensity measurement sensors 52 ′ for measuring the inclination angle in the vertical direction are also input to the received light intensity analysis inclination angle calculation unit 53, and the received light intensity analysis inclination angle calculation unit 53 performs the light intensity measurement sensor. The horizontal inclination angle is calculated from the light intensity measurement value measured at 54, and the vertical inclination angle is calculated from the light intensity measurement value measured by the light intensity measurement sensor 54 ′. The tilt angle in the vertical direction is combined and output to the image control unit 23, and the image control unit 23 generates LSI control parameters in consideration of the tilt in the horizontal direction and the vertical direction. In this case, the same processing is performed as described in the first embodiment even if the light receiving unit is a convex lens 56 instead of the pinhole 51.

1 is a schematic block configuration diagram of a projector including an automatic trapezoidal distortion correcting unit according to a first embodiment of the present invention. It is a schematic diagram of the projector provided with the automatic trapezoid distortion correction means of the 1st Embodiment of this invention. (A) is a front view. (B) is a side view. (C) is a top view. It is a schematic diagram which shows the state of the reflected light of the uniform luminance light projected on the screen from the projection apparatus. (A) is a state in which the inclination angle between the projection optical axis and the screen is 90 °. (B) is the case of the first tilt angle. (C) is a case of the 2nd inclination angle smaller than the 1st inclination angle. (D) is a distribution of light intensity measurement values according to the incident angle of the light beam on the screen and the reflection angle of the reflected light beam. When the screen is a high gain screen, the position of the light intensity measurement sensor shown with the horizontal axis as the reference line, and the light intensity measurement value selected when the vertical axis is the light intensity measurement value measured by the light intensity measurement sensor. It is a schematic diagram which shows the quadratic curve which connects the front-end | tip of a bar graph. (A) is a state in which the inclination angle between the projection optical axis and the screen is 90 °. (B) is the case of the first tilt angle. (C) is the case of the second tilt angle. It is a typical flowchart which shows the process which corrects the output image of a display part from the light intensity measurement value of a some light intensity measurement sensor. It is a schematic diagram which shows the light-incidence state to the light intensity measurement sensor of the reflected light from a screen at the time of using a convex lens as a light guide part. It is a typical block block diagram of the projector provided with the automatic trapezoid distortion correction means of the 2nd Embodiment of this invention. It is a typical block block diagram of the projector provided with the automatic trapezoid distortion correction means of the 3rd Embodiment of this invention. These are the schematic diagrams of the projector provided with the automatic trapezoid distortion correction means of the 3rd Embodiment of this invention. (A) is a front view. (B) is a side view. (C) is a top view. It is a schematic diagram which shows the state of the reflected light of the uniform luminance light projected on the screen from the projector of the prior art example. (A) is a state in which the inclination angle between the projection optical axis and the screen is 90 °. (B) is the case of the first tilt angle. (C) is a case of the 2nd inclination angle smaller than the 1st inclination angle. A quadratic curve connecting the position of the light intensity measurement sensor with the horizontal axis of the conventional example as the reference line and the tip of the bar graph of the light intensity measurement value when the vertical axis is the light intensity measurement value measured by the light intensity measurement sensor It is a schematic diagram which shows. (A) is a state in which the inclination angle between the projection optical axis and the screen is 90 °. (B) is the case of the first tilt angle. (C) is the case of the second tilt angle. (D) is a case where the screen is a high gain screen at the second tilt angle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Projector 20 Projector 21, 121 Projection lens 22 Display part 23 Image control part 24 Input image 25 Output image 27 Projection optical axis 28 Reference surface 29 Reference line 30 Inclination angle measuring device 31 Projection light 32 Reflected light 33 Main reflected light 51, 51 ′, 151 Pinhole 52, 52L1, 52L2, 52C, 52R1, 52R2, 52 ′, 52′L, 52′C, 52′R, 152, 152L, 152C, 152R Light intensity measurement sensor 53 Light reception intensity analysis inclination angle Calculation unit 54 Vertical inclination sensor 56 Convex lens 60 Central processing unit 70 Screen 81 Quadratic curve 82 Vertex 83 Actual light intensity S1 to S6 Steps

Claims (12)

A projection device having a display unit and a projection lens and projecting an image on a screen, an inclination angle measuring device for calculating an inclination angle of the projection optical axis of the projection device with respect to the screen, and the display unit according to the calculated inclination angle In a projector provided with an automatic trapezoidal distortion correcting means composed of an image control unit that corrects the trapezoidal distortion of the video projected on the screen by controlling the output video of
The projection device has uniform luminance light output means for projecting uniform luminance light, which is light of uniform luminance, from the projection lens of the projection device onto the screen,
The tilt angle measuring device includes:
One guide provided on the housing wall surface of the projector at a predetermined interval in a direction perpendicular to the projection optical axis with respect to a reference plane including the projection optical axis, which is a plane on which the tilt angle is calculated. Hikari and
A plane parallel to the reference plane and a plane perpendicular to the projection optical axis so as to receive the reflected light from the screen of the uniform luminance light passing through the light guide unit inside the projector housing. At least four light intensity measuring sensors that are provided in a line on a reference line that is an intersecting line and that measure the light intensity of the reflected light received;
From the light intensity measurement results of at least four light intensity measurement sensors, three light intensity measurement values are selected in descending order of the light intensity measurement values, and the positions of the selected three light intensity measurement values on the reference line are selected. Is the horizontal axis, and the vertical axis is the light intensity at that position, an approximate quadratic curve connecting the tip of the bar graph of the light intensity measured at each position is calculated, And the intersection between the reference line and the plane perpendicular to the reference plane including the projection optical axis of the reference line, and from a preset correlation between the distance and the tilt angle, A projector including an automatic trapezoidal distortion correction unit, comprising: a received light intensity analysis inclination angle calculation unit that calculates the inclination angle on a reference plane and outputs the calculated inclination angle to the image control unit.   The projector with automatic trapezoidal distortion correction means according to claim 1, wherein the reference plane is a horizontal plane, and the light guide section is arranged in a direction perpendicular to the projection optical axis.   The tilt angle measuring device further includes a vertical tilt sensor that detects a tilt angle of the projection optical axis on a vertical plane including the projection optical axis of the projector, and the vertical plane detected by the vertical tilt sensor. 3. The automatic trapezoidal distortion correction unit according to claim 2, wherein the output image of the display unit is controlled by combining the upper inclination angle and the inclination angle on the horizontal plane calculated using the light intensity measurement sensor. Projector.   The projector with automatic trapezoidal distortion correction means according to claim 1, wherein the reference plane is a vertical plane, and the light guide section is arranged in a horizontal direction from the projection optical axis. The reference planes are horizontal and vertical planes;
2. The automatic trapezoidal distortion correcting means according to claim 1, wherein the light guide unit is arranged in a vertical direction and a horizontal direction with respect to the projection optical axis, and the light intensity measurement sensor is provided for each. projector.   The automatic trapezoid according to any one of claims 1 to 5, wherein the uniform luminance light output means is a light source and a light valve of a display unit of the projection device, and the uniform luminance light is projection image light. A projector provided with distortion correction means.   The automatic trapezoidal distortion correction according to any one of claims 1 to 5, wherein the uniform luminance light output means is a light source and a light valve of a display unit of the projection device, and the uniform luminance light is infrared rays. A projector provided with means.   The projector having the automatic trapezoidal distortion correcting means according to claim 6 or 7, wherein the light source of the uniform luminance light is a high-pressure mercury lamp.   The projector provided with the automatic trapezoidal distortion correction means according to claim 6 or 7, wherein the light source of the uniform luminance light is an LED.   The projector provided with the automatic trapezoid distortion correction means according to any one of claims 1 to 9, wherein the light intensity measurement sensor is a phototransistor.   The projector provided with the automatic trapezoid distortion correction means according to any one of claims 1 to 10, wherein the light guide portion is a pinhole provided on a wall surface of the projection device.   The projector provided with the automatic trapezoid distortion correction means according to any one of claims 1 to 10, wherein the light guide unit is an optical lens provided on a wall surface of the projection device.

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