JP3742074B2 - Projector having tilt angle measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a projector, and more particularly to a projector having an inclination angle measuring device for calculating an inclination angle between a projection optical axis of a projection device of a projector and a projection surface.
[0002]
[Prior art]
With the rapid development of liquid crystal technology and DLP (digital light processing) technology, the miniaturization and high performance of projectors have expanded the use of projectors for image projection, and large-scale replacements for display-type televisions at home. It is also attracting attention as a display device.
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 9-281597 [Patent Document 2]
[Patent Document 1] Japanese Patent Application Laid-Open No. 2001-169221
[Problems to be solved by the invention]
However, unlike a display television, a liquid crystal projector or a DLP projector has a problem that an image is distorted due to the relative relationship between the optical axis of the projector and the projection surface because the image surface is a screen or a wall. is there. Japanese Patent Application Laid-Open No. 9-281597 has 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, and the liquid crystal display unit is determined according to the angle calculated from both detection results. A method for adjusting the angle is disclosed. In this case, it is necessary to mechanically adjust the angle of the liquid crystal display unit. Japanese Patent Application Laid-Open No. 2001-169221 discloses that a light point of a laser pointer capable of angle control is projected on a curved screen, while a point image for measurement is generated, projected from the projector onto the screen, and photographed with a camera. Coordinate conversion parameter memory by replacing the pixel coordinates on the frame memory of the point image with the coordinates on the input image of the light point when the points coincide with each other while moving the point image by measuring the position of the light spot and the point image Distortion correction methods set in the above are disclosed. In this case, it is necessary to control the angle of the laser pointer, and the structure becomes complicated.
[0005]
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.
[0006]
Among these, since the projection surface is usually vertical for the inclination in the vertical direction, the degree of inclination of the projection device detected by using the inclination sensor using the acceleration detection element already put into practical use is projected to the projection surface. However, since there is no simple method for detecting horizontal inclination, correction is performed manually using a distortion correction function installed in the projector.
[0007]
An object of the present invention is to provide a projector having an inclination angle measuring device capable of accurately measuring an inclination angle of a screen with respect to a projection optical axis of a projector for image distortion correction with a simple configuration.
[0008]
[Means for Solving the Problems]
The projector having the tilt angle measuring device of the present invention is
It has a tilt angle measuring device that calculates the tilt angle between the projection optical axis of the projector and the projection surface, and controls the output image of the image display unit according to the calculated tilt angle to correct the image distortion on the projection surface. Projector. The tilt angle measuring apparatus includes a vertical tilt sensor using an acceleration detection element, a test pattern generation unit, a digital camera, and an image analysis tilt angle calculation unit. The test pattern generation unit passes through the projection lens from the projection device. A horizontal linear test pattern is projected onto the projection surface, and the test pattern on the projection surface is imaged with an image sensor of a digital camera arranged apart in the vertical direction above the projection lens, and the image analysis inclination angle calculation unit is Analyzing the test pattern pixels from the imaging screen of the image sensor to calculate the horizontal tilt angle between the projection optical axis of the projection device and the projection surface, and obtaining the vertical tilt angle of the projection device from the vertical tilt sensor Then, the distortion of the image on the projection surface is corrected by controlling the output video of the image display unit based on the acquired both inclination angles. The calculation of the horizontal inclination angle between the projection optical axis and the projection surface of the projection apparatus may be calculated from the difference pixel number information about the difference pixel number in the horizontal direction of the test pattern acquired from the imaging screen of the imaging element.
[0009]
The analysis of the inclination angle between the test pattern captured by the digital camera and the horizontal reference line is made in advance by calculating the difference in the number of pixels corresponding to the intersection of the test pattern and the both ends of the imaging screen. This is done by calculating the tilt angle using a table that associates a certain number of pixels with the tilt angle, and the tilt angle between the projection optical axis of the projector and the projection surface is calculated from the calculated tilt angle using a predetermined calculation formula. The control of the output video of the image display unit according to the tilt angle between the projection optical axis and the projection surface of the projection device of the projector may be performed based on the input video of the image display unit calculated in advance corresponding to the tilt angle. It may be executed by creating an LSI control parameter based on the correction value and controlling the projector image processing LSI.
[0010]
The projector may be a liquid crystal projector or a DLP (Digital Light Processing) projector.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic block diagram of a projector having a tilt angle measuring apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic explanatory diagram of a projector having a tilt angle measuring apparatus according to an embodiment of the present invention. (A) is a schematic top view showing a test pattern projection state, (b) is a schematic side view showing a test pattern projection state when the projection surface is not inclined in the horizontal direction, and (c) is a projection surface. The schematic side view which shows the test pattern projection state in the case where it inclines in a horizontal direction, (d) is a schematic front view of a projector, (e) is a digital camera when the projection surface is not inclined in the horizontal direction (F) is a schematic diagram of an imaging screen of a digital camera when the projection surface is inclined in the horizontal direction.
[0012]
Here, a liquid crystal projector will be described as an example, but the present invention can be similarly applied to a DLP (digital light processing) projector by replacing the liquid crystal display unit 22 with a DLP display unit.
[0013]
The projector 10 includes a projection device 20 having a projection lens 21 and a liquid crystal display unit 22, an image control unit 23 that controls an image on the liquid crystal display unit 22, a tilt angle measuring device 30, and a CPU 60 that controls the overall operation. Prepare. The tilt angle measuring device 30 analyzes the pixels of the image captured by the vertical tilt sensor 40, the imaging lens 51 and the image sensor 52, and the image captured by the image sensor 52 in the horizontal direction of the projection device 20. An image analysis inclination angle calculation unit 53 and a test pattern generation unit 54 that calculate the inclination and control the image control unit 23 together with the vertical inclination value detected by the vertical direction inclination sensor 40 are provided.
[0014]
The vertical direction inclination sensor 40 is an inclination sensor (G sensor) using an acceleration detecting element that is also used for centering the machine, and accurately measures the inclination angle with respect to the direction of gravity and outputs it as numerical data. To do. In general, since the vertical direction of the wall or screen that becomes the projection surface 70 is vertical, the detection value of the vertical direction inclination sensor 40 can be regarded as the vertical inclination angle between the projection optical axis 27 and the projection surface 70. When the vertical direction of the projection surface 70 is not vertical, the vertical inclination angle between the projection optical axis 27 and the projection surface 70 may be manually corrected.
[0015]
As shown in FIGS. 2A to 2C, the liquid crystal projector 10 is arranged so that an image is projected onto a projection surface 70 such as a screen or a wall. In this case, when projection is performed in a state where the projection optical axis 27 of the projection device 20 of the liquid crystal projector 10 and the projection surface 70a are orthogonal to each other, the screen of the liquid crystal display unit 22 is projected on the projection surface 70a as it is. When the projection optical axis 27 and the projection surface 70b of the apparatus 20 are inclined, the distance from the projection lens 21 changes depending on the position as compared with the case where they are orthogonal to each other. This causes a problem of trapezoidal distortion. In order to solve this problem, for example, a device as described in the above-mentioned patent document has been made. In this case, if the inclination angle between the projection optical axis 27 of the projection device 20 and the projection surface 70 can be accurately grasped, the image control unit 23 projects the image onto the projection surface 70 by moving the arrangement of the image on the liquid crystal display unit 22 to the pixels. The corrected image can be corrected to a correct state, and the mobility can be obtained numerically from the tilt angle.
[0016]
The object of the present invention is to accurately grasp the inclination angle between the projection optical axis 27 and the projection surface 70 of the projection apparatus 20, and the object is achieved by the inclination angle measuring apparatus 30 described below.
[0017]
In the tilt angle measuring device 30, as shown in FIG. 2 (d), an imaging lens 51 of a digital camera 50 having an imaging element 52 is disposed away from the projection lens 21 of the projection device 20 in the vertical direction.
[0018]
In the tilt angle measurement mode, the test pattern generation unit 54 of the tilt angle measurement device 30 controls the image control unit 23 to generate a horizontal linear test pattern 81 from the liquid crystal display unit 22 via the projection lens 21. Project to. 2E and 2F are imaging screens 80 when the test pattern 81 on the projection surface 70 is imaged by the imaging device 52 of the digital camera 50, and the projection optical axis 26 and the horizontal line of the projection surface 70a are orthogonal to each other. If so, the test pattern 81a is displayed horizontally regardless of the vertical inclination as shown in FIG. When the right side of the projection surface 70b is a horizontal plane and is inclined in a direction away from the projection lens 21, in the captured image 80 of the imaging element 52 imaged by the imaging lens 51 arranged in a direction away from the projection lens 21 vertically. As shown in FIG. 2 (f), the display is displayed with the right side tilted upward. Although not shown, when the left side toward the projection surface 70b is a horizontal plane and is inclined in a direction away from the projection lens 21, the left side is displayed in a tilted state.
[0019]
The pixel analysis inclination angle calculation unit 53 may calculate the inclination angle by analyzing the pixels of the test pattern 81b. For example, the difference in the number of pixels at the intersection of both ends of the imaging screen 80 and the test pattern 81b is calculated. Then, the tilt angle may be calculated using a table in which the difference pixel number and the tilt angle that are created in advance are associated with each other.
[0020]
FIG. 3 is a schematic flowchart showing a process of correcting the output image of the liquid crystal display unit 22 from the vertical inclination detected by the vertical inclination sensor 40 and the difference pixel number calculated by the pixel analysis inclination angle calculation unit 53. It is. The image analysis inclination angle calculation unit 53 acquires the difference pixel number information about the difference pixel number 87 in the horizontal direction of the test pattern 81b from the imaging screen 80 of the imaging element 52 (step S1), and based on this, the projection device 20 A horizontal inclination angle between the projection optical axis 27 and the projection surface 70 is generated (step S2), a vertical inclination angle is acquired from the vertical inclination sensor 40 (step S3), and image control is performed in response to the acquired both inclination angles. The unit 23 generates an LSI control parameter (step S4), and controls the projector image processing LSI (step S5), whereby the input video 24 is modified to become an output video 25 on the liquid crystal display unit 22. When the output video 25 is projected onto the projection surface, the output video 25 is similar to the input video 24.
[0021]
Here, the horizontal inclination angle between the projection optical axis 27 and the projection surface 70 of the projection device 20 is acquired by the pixel analysis inclination angle calculation unit 53, and the vertical inclination angle is acquired by the vertical inclination sensor 40. However, the vertical inclination angle may be obtained by arranging the imaging lens 51 in the lateral direction of the projection lens 21 and imaging the vertical test pattern projected from the projection lens 21 with the imaging element 52 through the imaging lens 51. Of course, this is possible, and the input image 24 may be corrected using the horizontal and vertical tilt angles obtained from the test pattern.
[0022]
【The invention's effect】
As described above, the present invention has an effect that it is possible to accurately measure the tilt angle of the projection plane required for correcting the distortion of the projector image with respect to the projection optical axis of the projector with a simple configuration.
[0023]
This is to project a horizontal linear test pattern from the projection device through the projection lens onto the projection surface, and image the test pattern on the projection surface with the image sensor of the digital camera arranged vertically above the projection lens, The image analysis tilt angle calculation unit of the tilt angle measuring device acquires the difference pixel number information about the difference pixel number in the horizontal direction from the imaging screen of the image sensor, and the horizontal tilt angle between the projection optical axis of the projection device and the projection surface This is because the image control unit corrects the input video and outputs the output video corresponding to the tilt in response to the obtained both tilt angles. .
[Brief description of the drawings]
FIG. 1 is a schematic block configuration diagram of a projector having an inclination angle measuring device according to an embodiment of the present invention.
FIG. 2 is a schematic explanatory diagram of a projector having an inclination angle measuring device according to an embodiment of the present invention.
(A) is a typical top view which shows a test pattern projection state.
(B) is a schematic side view showing a test pattern projection state when the projection surface is not inclined in the horizontal direction.
(C) is a schematic side view showing a test pattern projection state when the projection surface is inclined in the horizontal direction.
(D) is a schematic front view of a projector.
(E) is a schematic diagram of the imaging screen of a digital camera when the projection surface is not inclined in the horizontal direction.
(F) is a schematic diagram of the imaging screen of the digital camera when the projection surface is inclined in the horizontal direction.
FIG. 3 is a schematic flowchart showing a process of correcting an output image of a liquid crystal display unit from a vertical inclination detected by a vertical inclination sensor and a difference pixel number calculated by a pixel analysis inclination angle calculation unit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Projector 20 Projection apparatus 21 Projection lens 22 Liquid crystal display part 23 Image control part 24 Input image 25 Output image 27 Projection optical axis 30 Inclination angle measuring device 40 Vertical direction inclination sensor 50 Digital camera 51 Imaging lens 52 Imaging element 53 Image analysis inclination angle Calculation unit 54 Test pattern generation device 60 CPU
70, 70a, 70b Projection surface 80 Imaging screen 81a, 81b Test pattern 82 Pixel line 87 Horizontal difference pixel number S1-S5 Step

Claims (6)

A tilt angle measuring device that calculates the tilt angle between the projection optical axis of the projection device of the projector and the projection surface, and controls the output image of the image display unit according to the calculated tilt angle, thereby correcting the distortion of the image on the projection surface. A projector to correct,
The tilt angle measuring apparatus includes a vertical tilt sensor using an acceleration detection element, a test pattern generation unit, a digital camera, and an image analysis tilt angle calculation unit,
The test pattern generation unit projects a horizontal linear test pattern from the projection device through a projection lens onto the projection surface, and the test pattern on the projection surface is disposed apart in the vertical direction above the projection lens. captured by the image sensor of the digital camera, the image analysis inclination angle calculating portion, the horizontal slope of the projection surface and the projection optical axis of the front Symbol projector analyzes the pixels of the test pattern from the imaging screen of the imaging device An image of the projection plane is calculated by calculating an angle, obtaining a vertical tilt angle of the projection device from the vertical tilt sensor, and controlling an output video of the image display unit based on the acquired both tilt angles. A projector having an inclination angle measuring device that corrects the distortion of the projector. The calculation of the horizontal inclination angle between the projection optical axis of the projection device and the projection plane is calculated from the difference pixel number information about the difference pixel number in the horizontal direction of the test pattern acquired from the imaging screen of the imaging element. A projector comprising the tilt angle measuring device according to claim 1. The analysis of the inclination angle between the test pattern imaged by the digital camera and the horizontal reference line is to calculate the difference in the number of pixels corresponding to the intersection of the test pattern and both ends of the imaging screen, It is performed by calculating a tilt angle by a table in which a difference pixel number and a tilt angle created in advance are associated with each other, and the projection optical axis and the projection plane of the projection device according to a predetermined calculation formula from the calculated tilt angle The projector having the tilt angle measuring device according to claim 2 , wherein the tilt angle is calculated. The control of the output video of the image display unit according to the tilt angle between the projection optical axis of the projector of the projector and the projection surface is an input of the image display unit calculated in advance corresponding to the tilt angle. create an LSI control parameter by the correction value of the image, the projector having executed by controlling the projector image processing LSI, an inclination angle measuring device according to any one of claims 1 to 3. The projector having the tilt angle measuring device according to any one of claims 1 to 4 , wherein the projector is a liquid crystal projector. The projector having a tilt angle measuring device according to any one of claims 1 to 4 , wherein the projector is a DLP (digital light processing) projector.

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