JP2007121632A - Projector and screen - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projector capable of speedily correcting trapezoidal distortion before an actual images are projected after a power source is turned on. <P>SOLUTION: The projector 0 includes: an image projecting section 1 that projects an image onto a screen; an infrared projecting section 2 that projects infrared light onto the screen on which a prescribed pattern has been formed in advance with infrared reflection paint that reflects infrared light; infrared light receiving sections 31 and 32 that receive infrared light reflected from the pattern and output image data of a pattern corresponding to a light receiving position; and a computing section that processes the image data and computes the distance of the screen and the inclination angle of the screen. Since the pattern is formed from the infrared reflection paint that reflects infrared light, it does not disturb watching images during normal projection. The pattern reflects infrared light projected to the screen during measurement. Accordingly, the pattern can be optically imaged from the projector. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a projector including an image projection unit that projects an image on a screen. More particularly, the present invention relates to a technique for correcting a trapezoidal distortion of a projection screen by detecting a distance and an inclination to a screen.

When the image is enlarged and projected by the projector, the projection screen is displayed without distortion when projected from the front of the screen, that is, from the normal direction of the screen. On the other hand, when projected off the normal direction of the screen, the screen is distorted. Such strain is generally called trapezoidal strain. A method of correcting this trapezoidal distortion by video signal processing is known. In other words, this is a method of canceling the trapezoidal distortion by digitally processing the video signal and giving the video the reverse distortion. At that time, a method of detecting the distance to the screen and the tilt angle of the screen and automatically correcting the trapezoidal distortion based on the detected distance has been reported. For example, the following Patent Documents 1, 2, and 3 describe is there.
JP 05-347724 JP2004004284A JP 2004-109120 A

  A phase difference sensor based on the principle of triangulation is used as a device for optically detecting the distance to the screen and the tilt of the screen. Specifically, after the projector is turned on, it waits until an image is projected on the screen. The image projected on the screen is detected by a phase difference sensor, and the distance to the screen and the tilt of the screen are measured. However, the image projected on the screen may have a small contrast depending on the pattern, and accurate distance measurement may not be performed.

  There is also a method of projecting a chart pattern particularly suitable for distance measurement instead of an actual image. However, when the chart pattern is projected, the screen on the screen is switched from the normal video display to the chart pattern display, which causes a sense of incongruity. In general, since a projector starts up a light source for projection, it takes time from when the power is turned on until actual projection of an image starts. Therefore, even when a chart pattern is projected, it takes a certain amount of time since the power is turned on, so that the keystone distortion cannot be automatically corrected quickly.

  SUMMARY OF THE INVENTION In view of the above-described problems of the related art, an object of the present invention is to provide a projector that can quickly correct trapezoidal distortion before projecting an actual image after power-on. It is another object of the present invention to provide a screen suitable for such a projector. In order to achieve this purpose, the following measures were taken. In other words, the projector according to the present invention includes a video projection unit that projects an image on a screen, and a red light that projects infrared light onto a screen on which a predetermined pattern is formed in advance using an infrared reflective paint that reflects infrared light. An external light projecting unit, an infrared light receiving unit that receives infrared light reflected from the pattern and outputs image data of the pattern according to the light receiving position, and a distance to at least the screen by processing the image data And an arithmetic unit for calculating.

  Preferably, the infrared light receiving unit receives infrared light reflected from the first measurement site on the screen located in the first orientation, outputs first image data, and is located in the second orientation. Receiving infrared light reflected from the second measurement site on the screen and outputting second image data, and the calculation unit processes the first image data and distances to the first measurement site And processing the second image data to determine a distance to the second measurement site, and further, based on the first and second orientations and the distance to the first and second measurement sites, the first And the inclination of the screen along the direction connecting the second measurement sites. For example, the calculation unit obtains the inclination of the screen along the horizontal direction connecting the first and second measurement sites. Alternatively, the calculation unit obtains the inclination of the screen along the vertical direction connecting the first and second measurement sites. Preferably, the infrared light receiving unit includes a lens that collects infrared light reflected from a pattern formed on the screen, and one optical sensor array that is arranged near the focal position of the lens and outputs one image data. And the other photosensor array that is spaced apart in the baseline direction orthogonal to the optical axis of the lens and outputs the other image data, and the computing unit includes the one image data and the other image data. And the distance from the phase difference to the screen based on the principle of triangulation.

  The present invention also includes a screen suitable for the projector. That is, a screen having a plane for projecting an image projected from a projector, on which a chart pattern used for optically measuring a distance from the projector or an inclination with respect to the projector is formed, The chart pattern is formed on the flat surface with an infrared reflective paint that reflects infrared light, and does not interfere with image viewing during normal projection, and is projected toward the flat surface during measurement. The chart pattern can be optically imaged from a projector by reflecting infrared light.

  According to the present invention, the chart pattern is previously formed on the screen with the paint that reflects infrared light. Since this chart pattern is formed on the screen with a transparent infrared reflective paint, it is not visible to the human eye. Immediately after the projector is turned on, infrared light is projected onto the screen, and an infrared reflection image of the chart pattern is displayed on the screen. Although this infrared reflection image is not seen by the observer's eyes, it is detected by a phase difference sensor built in the projector. By analyzing the detected infrared reflection image, the distance to the screen and the tilt of the screen can be measured. Based on this measurement result, when an ornamental image is actually projected, a screen with the trapezoidal distortion corrected can be displayed. As described above, in the present invention, after the power is turned on, before projecting an image from a high-output light source for projection (for example, a strong halogen lamp), a dedicated infrared projector (small infrared lamp) is turned on to measure the distance. Can be performed promptly. Since trapezoidal distortion correction can be performed quickly from the distance measurement result, a screen without distortion can be viewed from the beginning during normal video display. Since the infrared reflection image of the chart pattern is not visible to the observer's eyes at all, it can be adjusted even while projecting an image on the screen.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic front view showing an overall configuration of a projector according to the present invention. As shown in the figure, the projector 0 includes a video projection unit 1, an infrared light projecting unit 2, infrared light receiving units 31 and 32, and the like. The image projection unit 1 is composed of a light bulb made of a liquid crystal panel and the like, a strong halogen lamp, and the like, and projects an image on a screen (not shown). The infrared light projecting unit 2 includes a small infrared lamp, and projects infrared light onto a screen on which a predetermined pattern is formed in advance with an infrared reflective paint that reflects infrared light. The infrared light receivers 31 and 32 receive the infrared light reflected from the pattern and output image data of the pattern corresponding to the light receiving position. In addition to this, the projector 0 has a built-in calculation unit, which processes image data output from the infrared light receiving unit 2 and calculates at least the distance to the screen. This calculation unit usually obtains the inclination of the screen in addition to the distance to the screen.

  FIG. 2 is a schematic plan view showing an example of the screen. As shown in the drawing, the screen 5 has a plane for projecting an image projected from the projector. On this plane, chart patterns 51 and 52 used for optically measuring a distance from a projector (not shown) or an inclination with respect to the projector are formed. In the illustrated example, the chart pattern 51 formed in the horizontal direction is used to measure the distance to the screen 5 and the horizontal inclination of the screen 5. The chart pattern 52 extending in the vertical direction is used for measuring the vertical inclination of the screen. These chart patterns 51 and 52 are formed in a plane with an infrared reflective paint that reflects infrared light, and do not hinder viewing of images during normal projection. At the time of measurement such as immediately after the power is turned on, the infrared light projected toward the plane of the screen 5 is reflected so that the chart patterns 51 and 52 can be optically imaged from the projector. The specific examples of the chart patterns 51 and 52 are not limited to those shown in FIG. 2, and various modifications can be considered. Basically, a high-contrast pattern in which a reflective part and a non-reflective part are periodically arranged as illustrated is practical. It is also possible to use a cross formed by crossing the horizontal chart pattern 51 and the vertical chart pattern 52. Moreover, although each reflection part contained in the chart patterns 51 and 52 is equal in width, the chart pattern which combined the thing from which a width | variety differs may be sufficient.

  In order to form the chart patterns 51 and 52 on the screen 5, a transparent infrared reflective paint is suitable. This transparent infrared reflective paint is commercially available, for example, under the trade name “At Shield Clear”. This transparent infrared reflective paint is a liquid in which a semiconductor metal oxide is micronized and dissolved in a solvent to form a substantially colorless coating film (visible light transmittance of 80% or more). On the other hand, it reflects about 35% of near infrared rays. Therefore, it is suitable for forming the chart patterns 51 and 52 shown in FIG.

  A product called a thermal barrier paint is also used for forming the chart patterns 51 and 52. This thermal barrier paint is commercially available, for example, under the trade name “ATTSU-9” from Nippon Paint Co., Ltd., which largely reflects infrared rays that account for 50% of the sun's rays and greatly suppresses the rise in the surface temperature of the paint area. Used for the purpose. This thermal barrier paint has a high reflectance of 70 to 80% in the infrared region of 1000 nm to 2000 nm. Therefore, it is suitable for forming the chart patterns 51 and 52 shown in FIG. This light-shielding paint is a mixture of a pigment having high infrared reflectance and ceramic beads mixed in a solvent in which a resin is dissolved, and has a function of greatly reflecting infrared rays.

  FIG. 3 is a schematic perspective view showing a usage state of the projector and the screen according to the present invention. The figure shows a case where the horizontal inclination of the screen 5 is measured. A distance to the screen 5 is measured in two directions in the optical axis 1A direction and the optical axis 1B direction using an infrared light receiving unit 31 incorporated in the front of the projector 0. In the figure, the two measurement sites are indicated by A and B. When measuring the vertical inclination of the screen 5, it is only necessary to select two measurement sites separated along the vertical chart pattern 52. In the example shown in the figure, an infrared light receiving unit built in the projector 0 switches the optical axis 1A and the optical axis 1B and measures the distances to the measurement parts A and B, respectively.

  Considering the triangle OAB with the infrared light receiving part built in the projector 0 as the origin O, the lengths of the sides OA and OB can be obtained by the distance measuring operation described above. The apex angle AOB is a deflection angle between the first optical axis azimuth 1A and the second optical axis azimuth 1B, and is known in the arithmetic unit built in the projector 0. Therefore, the triangle AOB is determined by the data of the side AO, the side BO, and the apex angle AOB. As a result, the angle formed by the side AB and the side AO can be obtained by simple geometric calculation. Since the first optical axis azimuth 1A (AO) is already known in the calculation unit, the azimuth of the side AB intersecting this with the angle OAB can be calculated. The direction of the side AB is the tilt angle of the screen 5. In the illustrated example, the side AB is a horizontal line along the chart pattern 51, and the horizontal inclination angle of the screen 5 is detected.

  FIG. 4 is a block diagram showing a specific configuration of the projector 0. As illustrated, the projector 0 includes a projection unit 1, an infrared light projecting unit 2, infrared light receiving units 31 and 32, a horizontal calculation unit 61, a vertical calculation unit 62, a control circuit 7, and an image circuit 8. The projection unit 1 is composed of a projection optical system, and projects an image displayed on a light valve such as a liquid crystal panel on a screen. The projection optical system that constitutes the projection unit has a zooming function and a focusing function. The video circuit 8 processes a video signal input from the outside and displays an original image on the light valve.

  When the projector 0 is powered on, the infrared projector 2 projects infrared light onto the screen prior to the projection operation of the projector 1. The infrared light receiving unit 31 receives an infrared reflected image of the chart pattern 51 formed on the screen. The horizontal calculation unit 61 calculates the image data of the chart pattern 51 and measures the distance to the screen and the tilt of the screen. Specifically, the infrared light receiving unit 31 receives infrared light reflected from the first measurement site A on the screen 5 located in the first orientation 1A and outputs first image data. Infrared light reflected from the second measurement site B on the screen located in the second orientation 1B is received, and second image data is output. The horizontal calculation unit 61 processes the first image data to determine the distance to the first measurement site A, processes the second image data to determine the distance to the second measurement site B, and further The inclination of the screen 5 along the direction connecting the first and second measurement parts A and B based on the first and second orientations 1A and 1B and the distances AO and BO to the first and second measurement parts. Ask for. In particular, the horizontal calculation unit 61 obtains the inclination of the screen 5 along the horizontal direction connecting the first and second measurement parts A and B. The projector 0 further includes an infrared light receiving unit 32 and a vertical calculation unit 62. The infrared light receiving unit 32 outputs an infrared reflected image of the chart pattern 52. The vertical calculation unit 62 processes the image data output from the infrared light receiving unit 32 by the same operation as the horizontal calculation unit 61 to obtain the inclination of the screen 5 along the vertical direction. The control circuit 7 executes keystone correction of the original image generated by the video circuit 8 based on the tilt angle data of the screen 5 output from the horizontal calculation unit 61 and the vertical calculation unit 62. As described above, when an image is enlarged and projected on the screen by the projector, the projection screen is displayed without distortion when projected from the front of the screen, that is, from the normal direction of the screen. On the other hand, when projected off the normal direction of the screen, the screen is distorted. Such strain is called trapezoidal strain. The control circuit 7 corrects this trapezoidal distortion by video signal processing. The control circuit 7 acts on the video circuit 8 to perform digital processing of the video signal, and cancels the trapezoidal distortion by giving the video itself a reverse distortion. For this reason, the horizontal calculation unit 61 and the vertical calculation unit 62 detect the horizontal tilt angle and the vertical tilt angle of the screen in advance, and the control circuit 7 automatically corrects the trapezoidal distortion based on this.

  FIG. 5 is a schematic diagram showing a specific configuration of the infrared light receiving unit 31. In the figure, a pair of lenses 31a and 31b are arranged apart from each other by a predetermined base line length b, and a pair of photosensor arrays 31c and 31d arranged away from the pair of lenses 31a and 31b by a focal length f. The images of the measurement target (chart pattern) 51 are respectively formed through different optical paths 1A and 1A ′. The measurement target 51 is assumed to be present at a position separated from the pair of lenses 31a and 31b by a distance LC in the front direction.

  When the measurement object 51 exists at an infinite position, the center of each image formed on the pair of photosensor arrays 31c and 31d is the reference position corresponding to the optical axes of the lenses 31a and 31b on the photosensor arrays 31c and 31d. Although the image is formed at (31c1, 31d1), when the measurement object 51 comes closer to the infinity position, one image is formed at a position shifted from the reference position 31d1 by α. The distance LC from the principle of triangulation to the measurement object 51 is LC = bf / α. Here, since the base line length b and the focal length f are constants, the distance LC can be measured by detecting the shift amount α. This is the operation principle of the active distance measuring device for infrared light triangulation, and the calculation unit 61 performs this calculation.

  The calculation unit 61 shown in FIG. 4 performs the correlation calculation on the partial video data groups extracted from the pair of video signals (image data) output from the pair of line sensors 31c and 31d. To detect. This correlation calculation is well known and will not be described in detail. However, in general, the region where the degree of coincidence is highest when the partial video data groups are overlapped is set, and the overlapping partial video data group is the alignment direction of the optical sensor array. This is an operation to detect while shifting relatively.

  As described above, the infrared light receiving unit 31 condenses the infrared light reflected from the pattern formed on the screen, and one of the image data that is arranged near the focal position f of the lens 31a and outputs one image data. The optical sensor array 31c and the other optical sensor array 31d that outputs the other image data are provided apart from each other in the base line direction b orthogonal to the optical axis 1A of the lens 31a. The horizontal calculation unit 61 obtains the phase difference α between the one image data and the other image data, and obtains the distance from the phase difference α to the screen based on the principle of triangulation.

  Finally, with reference to FIG. 6, the principle of distance measurement of the infrared light receiving unit when the direction different from the front is the distance measuring direction will be described. In the same figure, if the center of the image formed on the pair of photosensor arrays 31c and 31d when the measurement target 51 exists at an infinite position in the direction 1B to be measured is the reference position (31c2, 31d2), distance measurement When the measurement object 51 approaches the infinity position in the direction 1B, an image of the measurement object 51 is formed at a position that is relatively shifted by α from these reference positions (31c2, 31d2). The distance LR from the principle of triangulation to the measurement object 51 is LR = bf / (α cos β). The angle β is an inclination angle of the distance measuring direction 1B with respect to the perpendicular 1A of the base line, and is an angle determined by determining the measuring direction 1B. Here, since the baseline length b, the focal length f, and cos β are constants, the distance LR can be measured by detecting the shift amount α. This is the principle of distance measurement when the direction different from the front is the distance measurement direction.

  Further, the distance LR ′ from the straight line with the extended base line length to the measurement target 51 is LR ′ = LRcos β = bf / α, and the distance LR ′ can be measured by detecting the shift amount α in the same manner as described above. When calculating, the angle β is not necessary.

  In this case as well, when performing the correlation calculation, the partial video data group extracted from one image data is fixed as a reference part, and the partial video data group extracted from the other image data is shifted as a reference part. The direction 1B shifted by an angle β with respect to the optical axis of the lens 31a can be set as the distance measuring direction. Therefore, by setting a plurality of reference positions according to the distance measuring direction, it is possible to detect distances in a plurality of directions with one line type active distance measuring device.

1 is a front view showing an overall configuration of a projector according to the present invention. It is a top view of the screen concerning the present invention. It is a perspective view which shows the use condition of the projector and screen concerning this invention. It is a block diagram which shows the structure of the projector concerning this invention. It is a schematic diagram which shows the structural example of the infrared light-receiving part contained in the projector concerning this invention. It is a schematic diagram which similarly shows the structural example of an infrared light-receiving part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 0 ... Projector, 1 ... Image | video projection part, 2 ... Infrared light projection part, 5 ... Screen, 31 ... Light receiving part, 32 ... Light receiving part, 51 ... Chart pattern 52 ... Chart pattern 61 ... Horizontal calculation unit 62 ... Vertical calculation unit

Claims (6)

An image projection unit for projecting an image on a screen;
An infrared light projecting unit that projects infrared light onto a screen on which a predetermined pattern is formed in advance with an infrared reflective paint that reflects infrared light;
An infrared light receiving unit that receives infrared light reflected from the pattern and outputs image data of the pattern according to a light receiving position;
A projector comprising: an arithmetic unit that processes the image data and calculates at least a distance to the screen. The infrared light receiving unit receives infrared light reflected from the first measurement site on the screen located in the first azimuth and outputs first image data, and the screen located in the second azimuth. Receiving the infrared light reflected from the second measurement site above and outputting the second image data;
The computing unit processes the first image data to obtain a distance to the first measurement site, processes the second image data to obtain the distance to the second measurement site, and further, the first and first 2. The inclination of the screen along a direction connecting the first and second measurement parts is obtained based on two orientations and distances to the first and second measurement parts. projector.     The projector according to claim 2, wherein the calculation unit obtains an inclination of the screen along a horizontal direction connecting the first and second measurement parts.     The projector according to claim 2, wherein the calculation unit obtains an inclination of the screen along a vertical direction connecting the first and second measurement sites. The infrared light receiving unit includes a lens that collects infrared light reflected from a pattern formed on the screen, one optical sensor array that is arranged near the focal position of the lens and outputs one image data, The other optical sensor array that is spaced apart in the baseline direction orthogonal to the optical axis of the lens and outputs the other image data,
2. The calculation unit according to claim 1, wherein the arithmetic unit obtains a phase difference between the one image data and the other image data, and obtains a distance from the phase difference to the screen based on a principle of triangulation. projector. A screen having a plane for projecting an image projected from a projector,
On the plane, a chart pattern used for optically measuring the distance from the projector or the tilt with respect to the projector is formed.
The chart pattern is formed on the plane with an infrared reflective paint that reflects infrared light, and does not interfere with image viewing during normal projection, and is projected toward the plane during measurement. Reflects infrared light,
Accordingly, the chart pattern can be optically imaged from a projector.

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