JP2005354232A - Image projection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image projection apparatus capable of quickly correcting trapezoidal distortion caused by a tilted projection face with high accuracy. <P>SOLUTION: The image projection apparatus includes: a projecting lens 2 for projecting image light to a projection face 6; a plurality of range finding means 3, 4, 5 for using reflected light resulting from the image light projected on the projection face and reflected therein to measure distances from the image projection apparatus to a plurality of positions 30, 40, 50 in the projection face respectively; and a correction means for correcting distortion in the projected image on the basis of the distances measured by a plurality of the range finding means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to an image projection apparatus that projects an image on a projection surface such as a screen, and more particularly to an image projection apparatus that can correct distortion of a projection image.

  In recent years, there are many cases where conferences and presentations are performed while materials created by a personal computer or the like are enlarged and projected on a screen by an image projection device such as a liquid crystal projector. In this case, the projector is carried from one conference room to another. Often used in. In such a case, it is necessary to determine the size of the projected image each time the installation location is changed and to focus the projection lens with respect to the screen. For this reason, recently, a projector that automatically performs focusing has been proposed.

  Portable projectors are often installed on a desk, and in this case, the projector should be placed so that the projected light is not scattered by the desk or the projected image is easy to see for an observer sitting on a chair. In many cases, the projection is performed in an inclined state. In this case, so-called trapezoidal distortion occurs in the projected image. For this reason, there has been proposed a projector that incorporates a tilt sensor in the projector and automatically corrects the trapezoidal distortion by detecting the tilt of the projector.

  However, since the tilt sensor generally uses gravity, the tilt of the projector can be detected, but the tilt of the screen as the projection surface cannot be detected. Similar to when the projector is tilted, trapezoidal distortion occurs when the screen is tilted. Therefore, a projector using a conventional tilt sensor cannot correct the trapezoidal distortion due to the tilt of the screen.

Patent Document 1 discloses a projector that detects the front / rear / left / right inclination of a screen by measuring the distance to a plurality of positions on a projection surface using a plurality of ultrasonic sensors, and corrects trapezoidal distortion based on the detection result. Proposed.
JP-A-8-9309 (paragraphs 0022 to 0023, 0029, 0036 to 0044, FIG. 2, etc.)

  However, when the distance to the projection surface is measured using an ultrasonic sensor, the distance measurement accuracy may be reduced due to reflection of ultrasonic waves by an object around the projection surface. Further, when measuring the distance to a plurality of positions using a plurality of ultrasonic sensors, interference between the ultrasonic waves becomes a problem, and it is difficult to measure the distance to the plurality of positions simultaneously. For this reason, a certain amount of time is required until the tilt of the screen is detected.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image projection apparatus capable of correcting a trapezoidal distortion caused by the inclination of the projection surface with high accuracy and speed.

  In order to achieve the above object, an image projection apparatus according to the present invention uses a projection lens that projects image light onto a projection surface, and reflected light from the projection surface of the image light. A plurality of distance measuring means for measuring the distance to a plurality of positions, and a correcting means for correcting distortion of the projected image based on the distance measured by the plurality of distance measuring means.

  According to the present invention, since the distance to a plurality of positions on the projection surface is optically detected using the projected image light, the inclination of the projection surface can be obtained accurately and in a short time. Therefore, it is possible to satisfactorily correct the trapezoidal distortion caused by the inclination of the projection surface.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows the configuration of a projector (image projection apparatus) that is an embodiment of the present invention. In the figure, reference numeral 1 denotes a projector body. Reference numeral 2 denotes a projection lens, from which image light is projected toward the screen 6. The projection lens 2 of the present embodiment is configured to be able to perform zooming and autofocus.

  Reference numerals 3, 4 and 5 denote optical distance measuring sensor units which are provided on the front surface of the projector body 1 apart from each other (for example, at three locations around the projection lens 2 as shown). The distance measuring sensor units 3, 4, and 5 connect line sensors 3 s, 4 s, and 5 s configured by arranging photoelectric conversion elements in a line and image light reflected from the screen 6 onto the line sensors 3 s, 4 s, and 5 s. It is composed of light receiving lenses 3L, 4L, and 5L for imaging.

  Here, the principle of distance measurement by the optical distance measuring sensor unit will be briefly described with reference to FIG.

  FIG. 5 shows the principle when the distance to the projection surface is measured by the triangulation method. 201 is a projection surface (screen 6) on which the image light IL is projected, 203 is a projection lens, and 204 is a line sensor. A light receiving lens 202 is disposed in front of the line sensor 204.

The image light IL reflected by the projection surface 201 forms an image on the line sensor 204 by the light receiving lens 202. The distance L from the projector main body 1 to the projection surface 201 is that the base line length between the projection lens 203 and the light receiving lens 202 is B, the focal length of the light receiving lens 202 is f, and the position on the optical axis of the light receiving lens 202 on the line sensor 204. When the image shift amount with reference to 204a is x,
L = B × f / x
Can be obtained.

  In FIG. 1, p denotes a liquid crystal panel as an image forming element, which forms an original image of an image projected by image light. The projector is connected to an image information supply device 60 such as a personal computer, a DVD player, a video deck, a video receiver including an antenna and a tuner. As described later, the projector is equipped with a liquid crystal panel drive circuit (see FIG. 2), and a video signal from the image information supply device 60 is input to the liquid crystal panel drive circuit. The liquid crystal panel p is driven so as to form an original image corresponding to.

  6p is a projection image projected on the screen 6 by image light. 30, 40, and 50 indicate the areas from which reflected light is received by the line sensors 3 s, 4 s, and 5 s on the screen 6. These areas are hereinafter referred to as ranging sensor units 3, 4, and 4, respectively. This is referred to as a detection region by 5.

  Reference numeral 8 denotes a trapezoidal distortion correction switch provided in the projector main body 1, and a trapezoidal distortion correction process, which will be described later, is executed when the user operates this switch. Reference numeral 9 denotes an autofocus switch provided in the projector main body 1. When the user operates this switch, an automatic focusing process for the screen 6 of the projection lens 2 described later is executed.

  In the projector configured as described above, when the projection lens 2 projects the image light from the liquid crystal panel p onto the screen 6 through the projection lens 2, and the projection image 6p is displayed, the distance measuring sensor units 3, 4, 5 are displayed. On the line sensors 3s, 4s and 5s, the reflected light from the corresponding detection areas on the screen 6 is imaged by the light receiving lenses 3L, 4L and 5L. As a result, the reflected light of the projected image light on the screen 6 is received by the distance measuring sensor units 3, 4, and 5 disposed at a predetermined baseline length away from the projection lens 2, and from the projector to the screen 6. A so-called active type triangulation system distance measuring system is formed.

  Here, the detection areas 30, 40, and 50 of the distance measuring sensor units 3, 4, and 5 are positions on the screen 6 where the projection optical axis (extension line of the optical axis of the projection lens 2) AXL intersects, that is, the projection image 6p. Are set in the vicinity of the optical axis, the upper end, and the lateral end of the optical axis. The detection areas 30, 40, and 50 are all end portions of the projection image 6p within a predetermined size range on the screen 6, in other words, the projection image 6p on the screen 6 and an area outside the projection image 6p (outside image area). And the longitudinal direction of each detection region (longitudinal direction of each line sensor) is set to be orthogonal to the direction in which the end (boundary) of the projection image 6p extends. Specifically, the detection areas 30 and 40 in the vicinity of the optical axis and the upper end corresponding to the distance measuring sensor units 3 and 4 respectively extend in the vertical direction so that the vicinity (lower end) and upper end of the projection image 6p are near the optical axis. The detection region 50 at the lateral end corresponding to the distance measuring sensor unit 50 is a region extending in the left-right direction and including the lateral end of the projection image 6p.

  As a result, when the projected image 6p is an all-white image or a bright image, the difference in brightness between the projected image 6p and the outside area of the image is large, so the end portions (boundaries) of the projected image 6p are detected by the line sensors 3s, 4s, and 5s. ) Can be easily detected as an edge, and distance measurement accuracy can be improved.

  Thus, the distance to each image edge position of the screen 6 can be measured based on the image shift amount with respect to the image reference position on the line sensors 3s, 4s, and 5s. That is, the distance to the optical axis vicinity portion on the screen 6 is measured based on the image shift amount at the lower end of the image on the line sensor 3s, and the distance from the image shift amount at the upper end of the image on the line sensor 4s to the upper end portion on the screen 6. Is measured. Further, the distance from the image shift amount at the horizontal end of the image on the line sensor 5s to the horizontal end of the screen 6 is measured.

  Since the magnification of the projection image 6p is substantially proportional to the projection distance, the trapezoidal distortion factor of the projection image 6p in the vertical direction is determined based on the measured distance to the vicinity of the optical axis of the screen 6 and the distance to the upper end. It can be calculated. Similarly, the trapezoidal distortion factor of the projected image 6p in the left-right direction can be calculated based on the measured distance to the vicinity of the optical axis of the screen 6 and the distance to the lateral end.

  Based on the trapezoidal distortion rate of the projection image 6p calculated in this way, the shape of the original image formed on the liquid crystal panel p is set to a shape that eliminates the trapezoidal distortion, thereby correcting the trapezoidal distortion. A rectangular projection image 6p can be obtained.

  FIG. 2 shows the configuration of a system that corrects the trapezoidal distortion of the projected image caused by the tilt of the screen 6. In FIG. 2, 11 is an output circuit (upper sensor output circuit) of the upper sensor unit 4 that measures the distance to the upper edge of the screen 6 (around the upper edge of the projected image) among the three distance measuring sensor units 3 to 5. Reference numeral 12 denotes an output circuit (optical axis sensor output circuit) of the optical axis sensor unit 3 for measuring the distance to the optical axis vicinity portion (periphery of the lower end of the projection image) of the screen 6, and 13 denotes a horizontal end portion (projection image of the projection image). It is an output circuit (lateral end sensor output circuit) of the lateral end sensor unit 5 that measures the distance to the periphery of the lateral end).

  14 is an upper end distance calculating circuit for calculating the distance to the upper end of the screen 6, 15 is an optical axis distance calculating circuit for calculating the distance to the vicinity of the optical axis of the screen 6, and 16 is a distance to the horizontal end of the screen 6. This is a lateral end distance calculation circuit for calculating.

  Reference numeral 17 denotes a vertical trapezoidal distortion correction value calculation circuit that calculates a vertical trapezoidal distortion correction value, and reference numeral 18 denotes a horizontal trapezoidal distortion correction value calculation circuit that calculates a horizontal trapezoidal distortion correction value.

  A liquid crystal panel drive circuit 19 drives the liquid crystal panel p, and a zoom position output circuit 20 detects the zoom position of the projection lens 2.

  The upper end distance calculation circuit 14 calculates the distance to the upper end portion of the screen 6 based on the image shift amount on the line sensor 4s output from the upper end sensor output circuit 11, and outputs the calculated distance. Similarly, the optical axis distance calculation circuit 15 and the horizontal end distance calculation circuit 16 are based on the image shift amounts on the line sensors 3s and 5s output from the optical axis sensor output circuit 12 and the horizontal end sensor output circuit 13, respectively. The distance to the vicinity of the optical axis 6 and the distance to the lateral end are calculated and output.

  When calculating the distance to the upper end and the horizontal end, it is necessary to correct the image shift amount on the line sensors 4s and 5s based on the zoom position information obtained from the zoom position output circuit 20. This is because the positions of the upper end of the image and the horizontal end of the image on the line sensors 4s and 5s change according to the zoom position. On the other hand, in the vicinity of the optical axis, the lower end of the image on the line sensor 3s hardly changes because it is close to the projection optical axis AXL, and the above correction is not necessary.

  The vertical trapezoidal distortion calculation circuit 17 calculates the vertical trapezoidal distortion based on the two distance information output from the upper end distance output circuit 14 and the optical axis distance output circuit 15, and further corrects the trapezoidal distortion. The correction value for output is output.

  Further, the left-right direction trapezoidal distortion calculation circuit 18 calculates a horizontal keystone distortion based on the two distance information output from the optical axis distance output circuit 15 and the lateral end distance output circuit 16, and further, the trapezoid distortion A correction value for correcting the error is output.

  In addition, it is also possible to calculate the trapezoidal distortion in the vertical direction and the horizontal direction from a combination different from the above-described combinations among the above three distances.

  These output trapezoidal distortion correction values are input to the liquid crystal panel drive circuit 19. The liquid crystal panel drive circuit 19 corrects the shape of the original image formed on the liquid crystal panel p in the vertical direction and the horizontal direction based on the correction value. Thereby, the projection image 6p in which the trapezoidal distortion in each direction is favorably corrected is displayed on the screen 6.

  The operation of each circuit is controlled by the control circuit 21.

  FIG. 3 is a flowchart simply showing the flow of the trapezoidal distortion correction process. In step (abbreviated as S in the figure) 101, when the user operates the trapezoidal distortion correction switch 8, the control circuit 21 causes the zoom position output circuit 20 to output zoom position information in step 102. Next, in step 103, the upper end distance calculation circuit 14, the optical axis distance calculation circuit 15 and the lateral end distance calculation circuit 16 are caused to perform a distance calculation based on the output from each line sensor.

  Here, in this embodiment, since the distance is measured using the reflected light of the image light on the screen 6, the accuracy is lowered by an object (for example, furniture or lighting equipment in the room) around the screen 6. Ranging can be performed without any problem, and the above three distances can be measured simultaneously. Therefore, the entire trapezoidal distortion correction can be completed in a short time.

  In step 104, the vertical trapezoidal distortion calculation circuit 17 and the horizontal trapezoidal distortion calculation circuit 18 are made to calculate a trapezoidal distortion correction value based on the distance calculation result. Finally, in step 105, the liquid crystal panel drive circuit 19 is caused to perform original image shape correction (trapezoidal distortion correction) based on the trapezoidal distortion correction value.

  FIG. 4 is a diagram for explaining a distance measuring method by the active type triangulation method shown in FIG. 1, taking the upper end of the projected image 6p as an example. In the figure, 2 is a projection lens, p is a liquid crystal panel, 4L is a light receiving lens, and 4s is a line sensor (upper sensor unit 4).

  6a is the position of the screen 6 when it is vertically arranged so as to be orthogonal to the optical axis (projection optical axis) AXL of the projection lens 2, and 6b is when it is arranged at an angle of θ with respect to the screen position 6a. The position of the screen 6 is shown.

  Furthermore, yp is the height of the lower end of the original image on the liquid crystal panel p, fo is the focal length of the projection lens 2 (which varies depending on zooming), s10 is the distance on the optical axis from the projection lens 2 to the screen 6, and S1 is tilted by θ. The distance of the upper end of the image on the screen 6, θT is the angle of view of the projected image 6p with respect to the lower end (height yp) of the original image on the liquid crystal panel p projected onto the screen 6, and θT0 is the direction of the optical axis of the light receiving lens 4L. An angle expressed with reference to the optical axis AXL of 2 and d is a distance to the light receiving lens 4L with reference to the optical axis AXL of the projection lens 2.

  Here, θT is an angle determined from the focal length fo of the projection lens 2 and the height yp of the lower end of the original image of the liquid crystal panel p. When the projection lens 2 is a zoom lens, it changes due to zooming. The angle θT0 is preferably adjusted to the angle of view θT at the wide-angle end of the projection lens 2 so that an accurate projection distance is measured at the wide-angle end of the frequently used projection lens 2.

  In the figure, fAF is the focal length of the light receiving lens 4L, s1a is the distance from the light receiving lens 4L to the projected image on the screen position 6a in the optical axis direction of the light receiving lens 4L, and S1b is the light receiving lens 4L in the optical axis direction of the light receiving lens 4L. To the projected image on the tilted screen position 6b.

  FIG. 4 represents a case where θT0 matches the angle of view θT of the projected image. Also, in FIG. 4, an active type triangular ranging optical system in which an image projected from the projection lens 2 at an angle of view θT forms a light projecting system, a light receiving sensor unit 4 forms a light receiving system, and a base line length is d × cos θT. The system is configured.

  Image shift amounts ysa and ysb on the line sensor 4s corresponding to the screen positions 6a and 6b in the figure are generated as follows. Note that the image reference position of the image shift amount is a position on the optical axis of the light receiving lens 4L.

ysa = (d × cos θT) × fAF / S1a
ysb = (d × cos θT) × fAF / S1b
Similarly, an image shift amount is generated on the line sensors 3s and 5s of the light receiving sensor units 3 and 5. Therefore, conversely, if the image displacement amounts ysa and ysb on the line sensor are detected, the distances S1a and S1b to the upper end of the projected image up to each screen position (that is, the upper end portion of the screen 6 including the upper end of the projected image). Is required.

  Note that the distances S10 and S1 in the optical axis direction of the projection lens 2 and the heights yLa and yLb of the projection image 2 are converted from the distances S1a and S1b in the field angle θT direction by the following equations.

S10 = S1a × cos θT + d × cos θT × sin θT
yLa = S1a × tan θT
S1 = S1b × cos θT + d × cos θT × sin θT
yLb = S1b × tan θT
Similarly, the distance to the horizontal end of the projection image (the horizontal end of the screen 6) and the height of the projection image are obtained. In the configuration shown in FIGS. 1 and 43, the distance to a plurality of positions in the projected image (that is, the screen 6) can always be obtained with the projector as a reference.

  If the distances S1 and S10 on the upper end of the image and on the projection optical axis (lower end of the image) are obtained, the enlargement ratio of the projected image is almost proportional to the projection distance, and thus the trapezoidal distortion factor Kc in the vertical direction of the image is obtained by the following equation.

Kc (%) = (S1 / S10-1) × 100
If distances to a plurality of positions on the projected image are obtained as described above, when the screen 6 is in a vertical arrangement (6a) and the projector is inclined, when the projector is in a horizontal arrangement and the screen 6 is inclined, In any case where both projectors are tilted, the trapezoidal distortion rate of the image projected from the projector is always obtained. Further, it is possible to cope with a case where an image is projected from the horizontal direction with the projector placed obliquely in front of the screen 6.

  By using the projection lens 2 in the active type triangulation projection system, the base line length with the light receiving system can be increased without taking up unnecessary space, enabling high-precision ranging. It becomes. As a result, the trapezoidal distortion rate can be accurately calculated, and a practically sufficient trapezoidal distortion correction can be performed.

  Here, as an example, the degree of tilt angle detection and trapezoidal distortion correction of the screen 6 is shown. First, the projection lens and the light receiving lens are assumed as follows.

Projection lens: Focal length (fo) 37-48mm (1.3x zoom)
Focal length of focus lens -66mm (located on projection side)
Vertical size of liquid crystal panel (yp) 13.824mm
The bottom of the projected image is near the projected optical axis position
Projection distance (s10) 1.6-6m
Light receiving lens: focal length (fAF) 10.7 mm,
Angle in the optical axis direction (θT0) -20.93 degrees Distance (d) between the optical axis of the projection lens and the light receiving lens 50 mm,
Baseline length (d × cos θT0) 46.7 mm as a triangulation system.

  Here, the projection lens 2 is a zoom lens. Further, the focus lens in the projection lens 2 is disposed on the screen 6 side (projection side), and is a lens having a constant feeding amount regardless of zooming.

  The angle θT0 in the optical axis direction of the distance measuring sensor unit 4 is set to the angle of view θT at the projection image end when the projection distance is 2.8 m and the wide angle end (focal length 37 mm of the projection lens 2). Therefore, when the angle of view at the upper end of the projected image changes due to focusing and zooming, an error due to the angle of view difference is added to the image shift amount. Since the image shift error amount can be calculated from the distance measurement value and the zoom position, correction is performed by subtracting the error amount from the output image shift amount, and the projector and the projected image upper end (upper end of the screen) are calculated from the corrected image shift amount. It is necessary to find the distance between them. Here, the following amount is subtracted as a correction value.

  In other words, when the corrected image shift amounts are ysca and yscb, the image shift amounts are expressed as follows.

ysac = ysa−fAF × tan (θT−θT0)
ysbc = ysb−fAF × tan (θT−θT0).

  The numerical values calculated as described above are shown in Table 1 below. The distances shown here are 1.6 m, 2, 8 m, 4 m, and 6 m, and correspond to 40 inch, 70 inch, 100 inch, and 150 inch projections at the wide angle end of the projection lens. One inch means 25.4 mm. W and T mean the wide-angle end (focal length 37 mm) and the telephoto end (focal length 48 mm) of the projection lens. Here, each numerical value is calculated assuming that the inclination angle of the screen is 20 degrees.

  The trapezoidal distortion Kc is obtained from the distance S1 to the upper end of the image and the distance S10 to the vicinity of the optical axis (lower end). The last numerical value is obtained by obtaining the screen tilt angle (represented as θc) from the distance to the upper and lower ends of the image in order to confirm the measurement accuracy. When obtaining the tilt angle of the screen 6, the image height yLb obtained from the projection angle of view θT is used. Although a shift of about 1 degree occurs on the telephoto end side, this is an error that is practically acceptable for performing distortion correction.

上記と同様の要領で、左右方向の台形歪率も演算することができる。

In the same manner as described above, the trapezoidal distortion rate in the left-right direction can also be calculated.

  In this embodiment, since distance measurement is performed at three positions on the projected image end, projection is controlled by controlling the driving of the focusing lens of the projection lens based on the distance measurement result for at least one of these positions. The lens can also be automatically focused. That is, the trapezoidal distortion correcting distance measuring sensor can also be used as an auto force ranging sensor, and the number of components mounted on the projector can be reduced.

  Specifically, in response to the user operating the autofocus switch 9 provided in the projector body 1, the control circuit 21 determines the focus lens focus position in the projection lens 2 based on the distance measurement result. Calculate and drive the focus lens to the in-focus position.

  Here, as can be seen from Table 1, since the projection angle of view θT changes due to the focusing of the projection lens, after the automatic focus adjustment, the distance of the projected image edge is measured again, and the screen tilt angle is obtained again or automatically. By performing the trapezoidal distortion correction only after the focus adjustment, a more accurate trapezoidal distortion correction can be performed.

  In the above-described embodiment, the case where distance measurement is performed using a detection region including the projected image edge has been described. However, an image including an image pattern suitable for distance measurement in the vicinity of a plurality of image edges is projected onto a screen, and the plurality of images Ranging may be performed using a pattern. When projecting an image including such an image pattern, the control circuit 21 shown in FIG. 2 prevents the projection angle of view of the image pattern (that is, the position of the image pattern on the screen) from changing regardless of focusing or zooming. Alternatively, the liquid crystal panel drive circuit 19 may electrically control the position of the original image on the liquid crystal panel. When performing such projection with invariable projection angle of view, the amount of image shift on the line sensor does not change, so the projected image is based on distance measurement values for multiple locations obtained without correction by focusing and zooming. Can be calculated.

 As described above, according to the present embodiment, since the trapezoidal distortion rate is obtained based on the optical distance measurement result using the projection image, the keystone distortion correction considering the inclination of the screen itself can be performed. Moreover, it is possible to correct trapezoidal distortion caused by the tilt of the screen not only in the vertical direction but also in the horizontal direction.

1 is a diagram illustrating a configuration of a projector that is an embodiment of the present invention. FIG. FIG. 3 is a diagram illustrating an electric circuit configuration in the projector according to the embodiment. 6 is a flowchart illustrating a trapezoidal distortion correction operation in the projector according to the embodiment. FIG. 5 is a diagram illustrating a distance measuring method by the projector according to the embodiment. The figure explaining a triangulation method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Projector 2 Projection lens 3, 4, 5 Distance sensor unit 3L, 4L, 5L Photosensitive lens 3s, 4s, 5s Line sensor 6 Screen 6p Projection image

Claims (10)

A projection lens that projects image light onto the projection surface;
A plurality of distance measuring means for measuring the distance from the image projection device to a plurality of positions on the projection surface using the reflected light of the image light on the projection surface;
An image projecting apparatus comprising: a correcting unit that corrects distortion of a projected image based on the distances measured by the plurality of ranging units.   The plurality of distance measuring means includes a first distance measuring means that uses the reflected light from the first area in the projection image, and a second distance that is separated from the first area in a first direction. A second distance measuring unit that uses the reflected light from a region; and the reflected light from a third region that is separated from the first region in a second direction orthogonal to the first direction. The image projection apparatus according to claim 1, further comprising at least a third distance measuring unit. The correction means includes
Correcting distortion of the projected image in the first direction based on the distance detected by the first and second ranging means;
The image projection apparatus according to claim 2, wherein distortion of the projection image in the second direction is corrected based on the distances detected by the first and third ranging means.   4. The image projection apparatus according to claim 2, wherein the first area is an area closest to an optical axis position in the projection image among the first to third areas. 5. Detecting means for detecting a zoom state of the projection lens;
5. The image projection according to claim 1, wherein the correction unit corrects the distance measured by the distance measuring unit based on the zoom state detected by the detection unit. apparatus.   6. The distance measuring unit according to claim 1, wherein the distance measuring unit measures the distance using the reflected light from a region including an end of the projection image on the projection surface. Image projection device.   6. The distance measuring unit according to claim 1, wherein the distance measuring unit measures the distance using the reflected light from a region including the predetermined pattern in the projection image having the predetermined pattern. The image projection apparatus described. Detecting means for detecting a zoom state of the projection lens;
8. The apparatus according to claim 7, further comprising: a first control unit configured to perform control so that the position of the predetermined pattern does not move regardless of a zoom operation of the projection lens based on a zoom state detected by the detection unit. The image projection apparatus described in 1.   9. The apparatus according to claim 1, further comprising a second control unit that performs focus control of the projection lens based on a distance measured by at least one of the plurality of ranging units. The image projection apparatus as described in any one. An image projection device according to any one of claims 1 to 9,
An image display system comprising: an image information supply device that supplies image information for projecting an image to the image projection device.

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