Patent Publication Number: US-10769401-B2

Title: Image recognition device, image recognition method and image recognition unit

Description:
TECHNICAL FIELD 
     The present invention relates to an image recognition device, an image recognition method and an image recognition unit. 
     BACKGROUND ART 
     As an image recognition technology for detecting whether or not a finger has contact with a screen on which an image from a projector is projected, there is known a technology of PTL 1. In the image recognition technology of PTL 1, firstly, structured light having a lattice pattern is projected on the screen, and then a change in the lattice pattern at the position of the finger described above is recognized based on the image from an imaging device (a camera) to thereby perform touch recognition. 
     CITATION LIST 
     Patent Literature 
     PTL 1: US 2011/0254810 
     SUMMARY OF INVENTION 
     Technical Problem 
     However, in the image recognition technology described in PTL 1, the position detection accuracy in the depth direction of the finger viewed from the imaging device is low, and accordingly, there is a problem that the accuracy of the touch recognition is also low. 
     An object of the invention is to provide an image recognition device, an image recognition method and an image recognition unit capable of performing the touch recognition high in accuracy. 
     Solution to Problem 
     Such an object is achieved by the following aspects of the invention. 
     An image recognition device according to the invention is an image recognition device used in an image display unit including an imaging device adapted to image an image display surface, and a detecting image display device adapted to display a detecting image on the image display surface, the image recognition device including a pattern display section adapted to make the detecting image display device display a first pattern having a first linear pattern varying in luminance with a first pitch along a direction parallel to an epipolar line determined from a positional relationship between the imaging device and the detecting image display device, and a second linear pattern varying in luminance with a second pitch different from the first pitch along a direction parallel to the epipolar line, a measurement point determination section adapted to detect an object located between the imaging device and the image display surface to determine a measurement target point of the object, and a position detection section adapted to detect a position of the measurement target point with respect to the image display surface based on an image including the measurement target point and the first pattern obtained by the imaging device. 
     Thus, it is possible to perform the touch recognition (determination on whether or not the object has contact with the image display surface) with high accuracy based on the detection result of the position detection section. 
     In the image recognition device according to the invention, it is preferable that the second pitch is shorter than twice the first pitch. 
     Thus, it is possible to perform the touch recognition higher in accuracy. 
     In the image recognition device according to the invention, it is preferable that the first pattern is divided into a plurality of regions having a third pitch along a direction parallel to the epipolar line, and an address used to identify a position is assigned to each of the plurality of regions. 
     Thus, it is possible to detect the address in which the detection target point is located, and it is possible to display an auxiliary pattern (e.g., the second pattern described later) based on the address thus detected. Therefore, it is possible to perform the touch recognition higher in accuracy. 
     In the image recognition device according to the invention, it is preferable that the third pitch is equal to a lowest common multiple of the first pitch and the second pitch. 
     Thus, the possibility of occurrence of phase wrapping decreases, and the touch recognition higher in accuracy becomes possible (it should be noted that the phase wrapping will be described later). 
     In the image recognition device according to the invention, it is preferable that the pattern display section makes the detecting image display device display a second pattern having a linear shape along the epipolar line passing through the measurement target point except the region in which the measurement target point is located. 
     Thus, it is possible to distinguish the phase wrapping, and the touch recognition higher in accuracy becomes possible. 
     In the image recognition device according to the invention, it is preferable that the pattern display section makes the detecting image display device display a second pattern straddling the region in which the measurement target point is located and two regions adjacent to the region in which the measurement target point is located. 
     Thus, it is possible to distinguish the phase wrapping, and the touch recognition higher in accuracy becomes possible. 
     In the image recognition device according to the invention, it is preferable that the pattern display section makes the detecting image display device display a second pattern having a linear pattern along a direction parallel to the epipolar line, wherein the linear pattern is disposed in the plurality of regions adjacent to each other so as to be shifted from each other in a direction crossing the epipolar line. 
     Thus, it is possible to distinguish the phase wrapping, and the touch recognition higher in accuracy becomes possible. 
     An image recognition method according to the invention is an image recognition method used in an image display unit including an imaging device adapted to image an image display surface, and a detecting image display device adapted to display a detecting image on the image display surface, the image recognition method including a pattern display step adapted to make the detecting image display device display a first pattern having a first linear pattern varying in luminance with a first pitch along a direction parallel to an epipolar line determined from a positional relationship between the imaging device and the detecting image display device, and a second linear pattern varying in luminance with a second pitch different from the first pitch along a direction parallel to the epipolar line, a measurement point determination step adapted to detect an object located between the imaging device and the image display surface to determine a measurement target point of the object, and a position detection step adapted to detect a position of the measurement target point with respect to the image display surface based on an image including the measurement target point and the first pattern obtained by the imaging device. 
     Thus, it is possible to perform the touch recognition (determination on whether or not the object has contact with the image display surface) with high accuracy based on the detection result of the position detection section. 
     An image recognition unit according to the invention includes the image recognition device according to the invention, the imaging device, and the detecting image display device. 
     Thus, it is possible to obtain the image recognition unit capable of performing the touch recognition with high accuracy. 
     In the image recognition unit according to the invention, it is preferable to further include an image display device adapted to display an image on the image display surface. 
     Thus, it is possible to display a desired image on the image display surface. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram showing a configuration of an image recognition unit according to a first embodiment of the invention. 
         FIG. 2  is a configuration diagram of the projector shown in  FIG. 1 . 
         FIG. 3  is a configuration diagram of the projector shown in  FIG. 1 . 
         FIG. 4  is a plan view of a scanning section provided to the projector shown in  FIG. 3 . 
         FIG. 5  is a block diagram of the image recognition device shown in  FIG. 1 . 
         FIG. 6  is a diagram for explaining an epipolar line. 
         FIG. 7  is a diagram showing a first pattern. 
         FIG. 8  is a diagram for explaining a method of touch recognition. 
         FIG. 9  is a diagram for explaining the method of the touch recognition. 
         FIG. 10  is a diagram for explaining a method of the touch recognition. 
         FIG. 11  is a diagram for explaining the method of the touch recognition. 
         FIG. 12  is a diagram showing a detecting image used in an image recognition unit according to a second embodiment of the invention. 
         FIG. 13  is a diagram for explaining a method of the touch recognition. 
         FIG. 14  is a diagram for explaining the method of the touch recognition. 
         FIG. 15  is a configuration diagram of a projector used in an image recognition unit according to a third embodiment of the invention. 
         FIG. 16  is a diagram for explaining a method of the touch recognition. 
         FIG. 17  is a diagram for explaining the method of the touch recognition. 
         FIG. 18  is a diagram for explaining the method of the touch recognition. 
         FIG. 19  is a diagram showing a detecting image used in an image recognition unit according to a fourth embodiment of the invention. 
         FIG. 20  is a diagram for explaining a method of the touch recognition. 
         FIG. 21  is a diagram for explaining the method of the touch recognition. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Some preferred embodiments of the image recognition device, the image recognition method and the image recognition unit according to the invention will hereinafter be described with reference to the accompanying drawings. 
     First Embodiment 
     Firstly, an image recognition unit according to a first embodiment will be described. 
       FIG. 1  is a diagram showing a configuration of the image recognition unit according to the first embodiment of the invention.  FIG. 2  is a configuration diagram of the projector shown in  FIG. 1 .  FIG. 3  is a configuration diagram of the projector shown in  FIG. 1 .  FIG. 4  is a plan view of a scanning section provided to the projector shown in  FIG. 3 .  FIG. 5  is a block diagram of the image recognition device shown in  FIG. 1 .  FIG. 6  is a diagram for explaining an epipolar line.  FIG. 7  is a diagram showing a first pattern.  FIG. 8  through  FIG. 11  are each a diagram for explaining a method of touch recognition. 
     The image recognition unit  100  shown in  FIG. 1  is a device capable of determining whether or not a finger (an object) F has contact with, for example, a flat screen (an image display surface)  900 , and then switching an image to be displayed on the screen  900  based on the determination result. It should be noted that the determination on whether or not the finger F has contact with the screen  900  is hereinafter referred to as “touch recognition.” Such an image recognition unit  100  can be used for, for example, a presentation, and by performing the touch recognition of the finger of a presenter to switch, expand, or shrink an image to be displayed on the screen as needed, it becomes possible to smoothly progress the presentation. 
     It should be noted that the image display surface is not limited to the screen  900 , but can also be, for example, a wall or a glass. Further, the image display surface is not required to be flat, but can also be a spherical surface or an uneven surface. Further, the image display surface can change in shape with time. Further, the object on which the tough recognition is performed is not limited to the finger F, but can also be, for example, a pointer stick, or a magnet adhering to the screen  900 . Further, the use application of the image recognition unit  100  is not limited to presentations, but the image recognition unit  100  can be used for a variety of applications such as a store guide of a department store, or introduction and search for a line of business. 
     As shown in  FIG. 1 , such an image recognition unit  100  has an image display unit having a projector (an image display device)  200  for displaying an image on the screen  900 , a projector (detecting image display device)  300  for displaying a first pattern  800  (see  FIG. 7 ) as a detecting image on the screen  900 , and a camera (an imaging device)  400  for imaging the screen  900 , and an image recognition device  500  for performing the touch recognition. 
     It should be noted that the projector  300  and the camera  400  are disposed at positions different from each other. Further, the relative (geometric) positional relationship between the projector  300  and the camera  400  is constant, and the information related to the positional relationship is stored in a storage section not shown and provided to the image recognition device  500 , and is used arbitrarily. 
     Hereinafter, the projector  200 , the projector  300 , the camera  400  and the image recognition device  500  will be described in sequence. 
     [Projector  200 ] 
     The projector  200  is a device for displaying an image (e.g., an image for a presentation) intended to be viewed by an observer on the screen  900 . 
     Such a projector  200  is an LCD type projector, and is provided with liquid crystal display elements  240 R,  240 G,  240 B, a dichroic prism  250 , and a projection lens system  260  as shown in  FIG. 2 . Then, red light R enters the liquid crystal display element  240 R, green light G enters the liquid crystal display element  240 G, and blue light B enters the liquid crystal display element  240 B. 
     The liquid crystal display elements  240 R,  240 G,  240 B are transmissive spatial light modulators corresponding respectively to the primary colors of R, G, and B, and the light beams spatially modulated by the respective liquid crystal display elements  240 R,  240 G,  240 B are combined with each other by the dichroic prism  250 , and thus full-color picture light La is emitted from the dichroic prism  250 . Then, the picture light La thus emitted is enlarged and projected on the screen  900  by the projection lens system  260 . Thus, an image is displayed on the screen  900 . 
     The projector  200  is hereinabove described, but is not limited to the LCD type projector providing the projector  200  is capable of displaying an image on the screen  900 , and can also be, for example, a light scanning type projector, or a DMD type projector. 
     [Projector  300 ] 
     The projector  300  is a device for displaying the first pattern  800  on the screen  900 . 
     Such a projector  300  is a light scanning type projector, and is provided with a light source  310 , a scanning section  320 , and a projection lens system not shown as shown in  FIG. 3 . 
     The light source  310  has a light source  311 R for emitting a red laser beam, a light source  311 G for emitting a green laser beam, a light source  311 B for emitting a blue laser beam, collimator lenses  312 R,  312 G,  312 B for respectively collimating the light beams emitted from the light sources  311 R,  311 G,  311 B, a light combining section  313 , and a collecting lens  314 . 
     The light combining section  313  is an element for combining the laser beams from the light sources  311 R,  311 G,  311 B with each other to generate the modulated light Lb, and has three dichroic mirrors  313   a ,  313   b ,  313   c . Further, the modulated light Lb generated by the light combining section  313  is changed to have a desired NA (numerical aperture) by the collecting lens  314 , and is then guided to the scanning section  320 . 
     The scanning section  320  is an optical scanner capable of oscillating around two axes, and has a movable section  330  having a mirror  331 , shaft sections  341 ,  342  for supporting the movable section  330  so as to be able to oscillate around an axis J 1 , a drive frame section  350  for supporting the shaft sections  341 ,  342 , shaft sections  361 ,  362  for supporting the drive frame section  350  so as to be able to oscillate around an axis J 2  perpendicular to the axis J 1 , and a support section  370  having a frame-like shape for supporting the shaft sections  361 ,  362  as shown in  FIG. 4 . In such a scanning section  320 , by oscillating the movable section  330  around the axis J 1  with respect to the drive frame section  350  while oscillating the drive frame section  350  around the axis J 2  with respect to the support section  370  using a driver not shown, it is possible to perform two-dimensional scan with the modulated light Lb reflected by the mirror  331 . 
     Then, the modulated light Lb with which the scan is performed by the scanning section  320  is enlarged and projected on the screen  900  by the projection lens system not shown. Thus, the first pattern  800  is displayed on the screen  900 . 
     The projector  300  is hereinabove described, but is not limited to the light scanning type projector providing the projector  300  is capable of displaying the first pattern  800  on the screen  900 , and can also be, for example, the LCD type projector or a DMD type projector. Further, it is also possible to adopt a configuration of having a light source for emitting a laser and a diffractive grating for diffracting the laser emitted from the light source. Further, even in the case of the light scanning type projector, the configuration described above is not a limitation, and it is also possible to perform two-dimensional scan with the modulated light Lb using, for example, two single-axis oscillation type optical scanners. Further, it is also possible for the projector  300  to have a configuration capable of projecting two types of fixed patterns different from each other using a diffractive optical element and a laser source. 
     [Camera  400 ] 
     The camera  400  is a device for imaging the screen  900 . Such a camera  400  is, for example, an RGB camera, and has a light receiving unit  410  provided with a lens system  411  and an imaging element  412 , and a processing section not shown for processing a video signal from the imaging element  412 . 
     [Image Recognition Device] 
     The image recognition device  500  is a device for performing the touch recognition using the projector  300  and the camera  400  described above. 
     As shown in  FIG. 5 , such an image recognition device  500  has a pattern display section  510 , a measurement point determination section  520 , and a position detection section  530 . 
     The pattern display section  510  drives the projector  300  to display the first pattern  800  extending along an epipolar line EL (a pattern display step). 
     Here, before explaining the first pattern  800 , the epipolar line EL will briefly be described. The epipolar line EL is a line determined by a geometric (relative) positional relationship between the projector  300  and the camera  400 . Specifically, as shown in  FIG. 6 , an intersection point between a straight line (base line) l 2  connecting a camera center (principal point of the lens system  411 ) C 1  of the camera  400  and an angle alteration center (the center of the mirror  331 ) C 2  when performing the scan with the modulated light Lb of the scanning section  320 , and a virtual image plane π 2  of the projector  300  is referred to as an epipolar point Pe, and all of the straight lines passing through the epipolar point Pe in the virtual image plane π 2  are referred to as epipolar lines EL. 
     Further, as shown in  FIG. 6 , if a fingertip F 1  is included in the image of the camera  400 , a coordinate (in-plane coordinate) x of the fingertip F 1  in an image plane π 1  of the camera  400  is determined. The plane defined by the straight line l 1  passing through the coordinate x and the camera center C 1 , and the straight line l 2  is referred to as an epipolar plane Σ. Further, in the case of defining the epipolar line EL coinciding with a straight line l 3 , which is obtained by the epipolar plane Σ and the virtual image plane π 2  intersecting with each other, as the “epipolar line EL′,” the fingertip F 1  is located somewhere on the epipolar line EL′. 
     As shown in  FIG. 7 , the first pattern  800  has a configuration in which a plurality of patterns extending in parallel to the epipolar line EL is arranged in the width direction (a direction crossing the epipolar line EL) of the epipolar line EL. It should be noted that  FIG. 7  shows an image obtained by performing a stereo-collimating process (an epipolar line horizontalizing process) on the image obtained by the camera  400 . Therefore, all of the epipolar lines EL become roughly parallel to each other, and are set in the state of extending in a horizontal direction (the lateral direction in the sheet). 
     Specifically, the first pattern  800  has first linear patterns  800 A and second linear patterns  800 B extending in a direction parallel to the epipolar line EL, and has a configuration in which the first linear patterns  800 A and the second linear patterns  800 B are arranged alternately in the width direction (the vertical direction in the sheet) of the epipolar line EL. 
     The first linear patterns  800 A each have a pattern varying in luminance with a first pitch T 1 . Specifically, the first linear patterns  800 A each have first regions  810 A having a predetermined luminance, and second regions  820 A having a different luminance from that of the first regions  810 A, wherein the first and second regions  810 A,  820 A are alternately arranged to have the same width T 1 . Similarly, the second linear patterns  800 B each have a pattern varying in luminance with a second pitch T 2  different from the first pitch T 1 . Specifically, the second linear patterns  800 B each have first regions  810 B having a predetermined luminance, and second regions  820 B having a different luminance from that of the first regions  810 B, wherein the first and second regions  810 B,  820 B are alternately arranged to have the same width T 2 . It is preferable for the luminance of the first regions  810 A ( 810 B) and the luminance of the second regions  820 A ( 820 B) to be determined so that the contrast ratio becomes as high as possible. Thus, the accuracy of the image recognition increases, and the touch recognition higher in accuracy becomes possible. 
     Here, the second pitch T 2  is not particularly limited, but is preferably shorter than twice the first pitch T 1 . If the second pitch T 2  is set equal to or longer than twice the first pitch T 1 , it results that two or more cycles of the first linear pattern  800 A are included in one cycle T 2  of the second linear pattern  800 B. Therefore, depending on the usage environment, there is a possibility that the accuracy of the depth analysis of the fingertip F 1  described later is deteriorated. It should be noted that in the present embodiment, the second pitch T 2  is made 1.75 times the first pitch T 1 . The reason therefor will be described later. 
     The first pattern  800  is described hereinabove, but is not limited to the above providing the first pattern  800  can be used for the touch recognition, and can also have a configuration in which, for example, a third linear pattern varying in luminance with a pitch different from the first pitch T 1  and the second pitch T 2  is further included, and the first, second, and third linear patterns are arranged in sequence and repeatedly. 
     The measurement point determination section  520  detects the finger F located between the camera  400  and the screen  900  from the image obtained by the camera  400 , and further, determines the fingertip F 1  of the finger F as a measurement target point (a measurement point determination step). 
     As the determination method of the fingertip F 1 , for example, the image of the screen  900  on which the first pattern  800  is projected is firstly obtained by the camera  400 , and then an image obtained by stereo-collimating the image is stored as a first pattern reference image. Then, it is possible to extract the contour of the finger F from a difference between the stereo-rectified image in which the fingertip F 1  is reflected together with the first pattern  800  and the first pattern reference image, then detect a part having a similar contour shape to the fingertip F 1  from the contour shape of the finger F thus extracted, and then determine the part thus detected as the fingertip F 1 . 
     It should be noted that the determination method of the fingertip is not limited to the above. For example, it is possible to extract a flesh-color-like area (an area having a color similar to the color of the finger F) using the HSV color system from the image obtained by the camera  400 , and further, detect a part having a similar contour shape to the fingertip F 1  from the contour shape of the flesh-color-like area thus extracted to determine the part thus detected as the fingertip F 1 . 
     The position detection section  530  detects the depth (position) of the fingertip F 1  based on the first pattern  800  included in the image obtained by the camera  400 , and performs the touch recognition based on the detection result (a position detection step). 
     Specifically, firstly, the position detection section  530  obtains an image (hereinafter also referred to as a “stereo-rectified image”) obtained by stereo-collimating the image obtained by the camera  400 . In the stereo-rectified image, the epipolar lines EL become lines parallel to the horizontal direction (the lateral direction in the sheet) irrespective of the unevenness of the surface of the screen  900 , the shape of the fingertip F 1 , and so on. Therefore, each of the first and second linear patterns  800 A,  800 B also becomes a straight line parallel to the horizontal direction, and it is possible to perform an analysis of the change of the first pattern  800  with ease and accuracy. 
     Then, the position detection section  530  detects the depth of the fingertip F 1  based on the first pattern  800  in the stereo-rectified image, and then performs the touch recognition based on the detection result. In the stereo-rectified image P 11  shown in  FIG. 8 , the first and second linear patterns  800 A,  800 B are projected not only on the screen  900 , but also on the fingertip F 1 . Further, in the stereo-rectified image P 11 , between the first pattern  800  on the screen  900  and the first pattern  800  on the fingertip F 1 , there occurs the pitch fluctuation (pattern shift) based on the depth of the fingertip F 1 . In other words, the first and second linear patterns  800 A,  800 B on the fingertip F 1  have the pitches T 1 ′, T 2 ′ different from the first and second pitches T 1 , T 2 , respectively. 
     Then, the position detection section  530  performs the depth analysis of the first and second linear patterns  800 A,  800 B reflected on the screen  900  to detect (estimate) the depth at the position overlapping the fingertip F 1  of the screen  900 , and at the same time, performs the depth analysis of the first and second linear patterns  800 A,  800 B reflected on the fingertip F 1  to detect the depth of the fingertip F 1 . 
     Then, if the depth of the fingertip F 1  does not coincide with the depth of the screen  900  in at least one of the analysis result of the first linear pattern  800 A and the analysis result of the second linear pattern  800 B, the position detection section  530  determines the “non-contact state” in which the fingertip F 1  does not have contact with the screen  900 . In contrast, in the case in which the depth of the fingertip F 1  coincides with the depth of the screen  900  in both of the analysis result of the first linear pattern  800 A and the analysis result of the second linear pattern  800 B, the position detection section  530  further performs the following determination. 
     For example, in the description of the first linear pattern  800 A, as shown in  FIG. 9 , even if the fingertip F 1  is separated from the screen  900 , in the case in which the way of the separation causes the pitch fluctuation (pattern shift) corresponding to an integral multiple of the pitch of the first linear pattern  800 A, there is obtained the same image of the pattern on the fingertip F 1  as that in the contact state in which the fingertip F 1  has contact with the screen  900  despite the non-contact state (hereinafter this phenomenon is referred to as “phase wrapping”). This similarly applies to the second linear pattern  800 B. 
     Therefore, in the case in which the way of the separation of the fingertip F 1  causes the pitch fluctuation corresponding to an integral multiple of the pitch of the first linear pattern  800 A, and at the same time causes the pitch fluctuation corresponding to an integral multiple of the pitch of the second linear pattern  800 B, the phase wrapping occurs. Therefore, it is necessary to distinguish between the contact state and the state in which the phase wrapping occurs. It should be noted that as described above, the pitch (the second pitch T 2 ) of the second linear pattern  800 B is 1.75 times the pitch (the first pitch T 1 ) of the first linear pattern  800 A. By adopting such a relationship, it is possible to make the lowest common multiple of the both pitches relatively large (i.e., 7 times the first pitch T 1 , 4 times the second pitch T 2 ), and therefore, it is possible to make the condition for causing the phase wrapping lower. 
     The method of distinguishing between the contact state and the state in which the phase wrapping occurs is not particularly limited, but the following method can be cited. That is, since in the stereo-rectified image P 11  in the case of the contact state, the fingertip F 1  has contact with the screen  900 , the shadow of the fingertip F 1  does not occur on the screen  900  as shown in  FIG. 10 . In contrast, since in the stereo-rectified image P 11  in the case in which the phase wrapping occurs, the fingertip F 1  is separated from the screen  900 , the shadow SH of the fingertip F 1  occurs on the screen  900  as shown in  FIG. 11 . Therefore, it is possible for the position detection section  530  to determine the “contact state” if the shadow of the fingertip F 1  does not occur in the screen  900  in the stereo-rectified image P 11 , and determine the “phase wrapping state” in which the phase wrapping occurs if the shadow occurs. 
     It should be noted that depending on the arrangement of the projector  300  and the camera  400 , the shape and size (the individual difference) of the fingertip F 1  and so on, the shadow SH occurs on the screen  900  despite the contact state in some cases. Therefore, it is also possible to set a threshold value for the width (size) of the shadow SH, and determine the “contact state” if the width of the shadow SH is smaller than the threshold value, and determine the “phase wrapping state” if the width of the shadow SH is equal to or larger than the threshold value. 
     In the case in which the determination result is the “contact state,” the position detection section  530  transmits the determination result to a control section not shown. The control section having received the determination result transmits a screen operation command determined in accordance with the contact position of the fingertip F 1  such as a command for expanding or contracting the image displayed on the screen  900 , or a command for switching the image to the projector  200 . By performing such control, it is possible to operate the image displayed on the screen  900  only by touching the screen  900  with the fingertip F 1 , and therefore, the image recognition unit  100  high in convenience is obtained. 
     As described above, it is the procedure (image recognition method) of the touch recognition by the image recognition device  500  to perform the pattern display step, the measurement point determination step, and the position detection step, and by repeatedly performing the procedure with a predetermined period, it is possible to repeatedly perform the touch recognition. 
     According to such an image recognition device  500 , the calculation load can be reduced, and at the same time, the touch recognition high in accuracy becomes possible. Further, the epipolar line EL is a line which can be obtained in accordance with the geometric positions of the projector  300  and the camera  400  irrespective of the three-dimensional position and the surface shape of the screen  900 . Therefore, once the geometric positions of the projector  300  and the camera  400  are set, it is possible to perform the touch recognition without being affected by the position and the shape of the screen  900 . In particular, as described above, since the occurrence of the phase wrapping is reduced by using the first pattern  800 , it is possible to perform the touch recognition high in accuracy. Conversely, it can be said that the periods of the first linear pattern  800 A and the second linear pattern  800 B can be shortened accordingly to the reduction of the occurrence of the phase wrapping, and accordingly, the touch recognition higher in accuracy becomes possible. 
     The first embodiment is hereinabove described. It should be noted that in the configuration described above, the first pattern  800  is generated using the visible light, but can also be generated using NIR light (near infrared light having the wavelength in a range of about 800 through 2500 nm). Since the NIR light is invisible to humans, there is no possibility that the first pattern  800  deteriorates the image from the projector  200  displayed on the screen  900 . Further, in this case, the first pattern  800  can be generated by, for example, setting the first regions  810 A,  810 B as NIR light irradiation regions, and the second regions  820 A,  820 B as NIR light non-irradiation regions. 
     Second Embodiment 
     Then, an image recognition unit according to a second embodiment of the invention will be described. 
       FIG. 12  is a diagram showing a detecting image used in the image recognition unit according to the second embodiment of the invention.  FIG. 13  and  FIG. 14  are diagrams for explaining a method of the touch recognition. It should be noted that in each of  FIG. 13  and  FIG. 14 , illustrations of the first pattern  800  are omitted for the sake of convenience of explanation. 
     Hereinafter, the image recognition unit according to the second embodiment of the invention will be described, wherein the description will be presented with a focus mainly on the differences from the embodiment described above, and the description regarding substantially the same matters will be omitted. 
     The image recognition unit according to the second embodiment is substantially the same as the first embodiment described above except the point that the configuration of the detecting image is different. It should be noted that the constituents substantially the same as those of the embodiment described above are denoted by the same reference symbols. 
     As shown in  FIG. 12 , in the present embodiment, an address pattern AD is projected together with the first pattern  800  as the detecting image. The address pattern AD is divided into a plurality of regions having a third pitch T 3  along a direction parallel to the epipolar line EL, and an address (information for identifying the position) is assigned to each of the regions. The method of assigning the addresses is not particularly limited, and there can be cited, for example, a method of disposing identification patterns for identifying the addresses in the respective regions. 
     The address pattern AD is specifically constituted by a pattern having the third pitch 7 times (4 times the pitch of the second linear pattern  800 B) the pitch of the first linear pattern  800 A, and is displayed on the upper side and the lower side of the first pattern  800 . Further, each pitch of the address pattern AD is provided with an address, and thus, it is arranged that the position of each pitch can be identified. Further, the width of one address is set slightly larger than the width of the fingertip F 1 . 
     It should be noted that the configuration of the address pattern AD is not particularly limited providing substantially the same advantages as described above can be exerted. For example, it is also possible for the address pattern AD to be displayed on at least one of the upper side and the lower side of the first pattern  800 . 
     Further, the projector  300  projects a second pattern  700  shown in  FIG. 13  in addition to the first pattern  800  as the detecting image. The second pattern  700  is a linear pattern extending on the epipolar line EL′ passing through the fingertip F 1 . Further, the second pattern  700  is projected so as to exclude the address [N+2] in which the fingertip F 1  is located, and include the addresses [N+1], [N+3] adjacent on both sides to the address [N+2]. It should be noted that the second pattern  700  can be generated using the visible light, or can also be generated using the NIR light. Further, the second pattern  700  can be displayed at the same time as the first pattern  800  and the address pattern AD, or can also be displayed alternately (in a time-sharing manner) with the first pattern  800  and the address pattern AD. 
     By using such the second pattern  700 , it is possible to accurately distinguish between the case in which the fingertip F 1  is in the contact state and the case of the state in which the phase wrapping occurs. Specifically, in the case of the contact state, the second pattern  700  is not projected on the fingertip F 1 . Therefore, as shown in  FIG. 13 , the stereo-rectified image P 21  at this moment becomes in the state in which the continuity of the second pattern  700  is maintained except in the address [N+2]. Further, since the second pattern  700  is not projected on the fingertip F 1 , the second pattern  700  does not overlap the first pattern  800  on the fingertip F 1 , and thus, it is possible to recognize the first pattern  800  on the fingertip F 1  as an image. In contrast, in the case in which the phase wrapping occurs, the second pattern  700  is projected on the fingertip F 1 , and thus, a part shadowed by the fingertip F 1  occurs somewhere in the second pattern  700 . Therefore, as shown in  FIG. 14 , a shadowed part  710  occurs in the second pattern  700 , and thus, the stereo-rectified image P 21  at this moment becomes in a discontinuous state. Further, since the second pattern  700  is projected on the fingertip F 1 , the second pattern  700  overlaps the first pattern  800  on the fingertip F 1 , and thus, it becomes difficult to recognize the first pattern  800  on the fingertip F 1  as an image. 
     From such a difference between the images, it is possible to accurately distinguish between the contact state and the state in which the phase wrapping occurs. Therefore, the touch recognition higher in accuracy becomes possible. 
     According also to such a second embodiment as described hereinabove, substantially the same advantages as in the first embodiment described above can be exerted. 
     Third Embodiment 
     Then, an image recognition unit according to a third embodiment of the invention will be described. 
       FIG. 15  is a configuration diagram of a projector used in the image recognition unit according to the third embodiment of the invention.  FIG. 16  through  FIG. 18  are each a diagram for explaining a method of the touch recognition. It should be noted that in each of  FIG. 16  through  FIG. 18 , illustrations of the first pattern  800  are omitted for the sake of convenience of explanation. 
     Hereinafter, the image recognition unit according to the third embodiment of the invention will be described, wherein the description will be presented with a focus mainly on the differences from the embodiment described above, and the description regarding substantially the same matters will be omitted. 
     The image recognition unit according to the third embodiment is substantially the same as the first embodiment described above except the point that the configuration of the projector (a detecting image display device) is different. It should be noted that the constituents substantially the same as those of the embodiment described above are denoted by the same reference symbols. 
     The projector  300  of the present embodiment is substantially the same as the projector  200  (see  FIG. 2 ), and is provided with liquid crystal display elements  381 R,  381 G,  381 B, a dichroic prism  382 , and a projection lens system  383  as shown in  FIG. 15 . A difference from the projector  200  is the point that it is arranged that the NIR light enters the liquid crystal display element  381 R together with the red light R. Since the red light R is smaller in wavelength difference from the NIR light compared to the green light G and the blue light B, it is possible to realize the same optical system with relative ease. According to the projector  300  having such a configuration, for example, it is possible to generate the first pattern  800  using the visible light, and generate the second pattern  700  using the NIR light, to thereby project the first pattern  800  and the second pattern  700  at the same time. 
     Here, if the second pattern  700  is projected with the NIR light using the projector  300  described above, the second pattern  700  is recognized as a red color (since the red light R is also modulated together with the NIR light). Therefore, there is a possibility that the image on the screen  900  is damaged by the second pattern  700 . Therefore, in order to prevent the image on the screen  900  from being damaged, in the present embodiment, as shown in  FIG. 16 , the second pattern  700  is improved in design to have a circular ring shape (ring shape) looking like a pointer. Further, the second pattern  700  is displayed so as to straddle the three cycles of the address pattern AD (specifically, the address [N+2] in which the fingertip F 1  is located, and the addresses [N+1], [N+3] adjacent on both sides to the address [N+2]). Further, an internal space  701  of the second pattern  700  is located so as to stride over the address [N+2] in which the fingertip F 1  is located. 
     Also by using such a second pattern  700 , it is possible to accurately distinguish between the case in which the fingertip F 1  is in the contact state and the case of the state in which the phase wrapping occurs. For example, as shown in  FIG. 16 , the stereo-rectified image P 31  in the case of the contact state becomes in the state in which the second pattern  700  is also projected on the finger F, and the second pattern  700  is displayed throughout the entire circumference. In contrast, in the case in which the phase wrapping of one cycle occurs, the second pattern  700  is projected on the finger F, and thus, the part shadowed by the finger F occurs in the second pattern  700 . Therefore, as shown in  FIG. 17 , the stereo-rectified image P 31  at this moment becomes in the state in which a part of the second pattern  700  is reflected as a shadow. Further, in the case in which the phase wrapping no smaller than two cycles occurs, the second pattern  700  is projected on a reverse side (screen  900  side) of the finger F. Therefore, as shown in  FIG. 18 , the stereo-rectified image P 31  at this moment becomes in the state in which a part of the second pattern  700  is reflected so as to be shadowed by the finger F. 
     From such a difference between the images, it is possible to accurately distinguish between the contact state and the state in which the phase wrapping occurs. Therefore, the touch recognition higher in accuracy becomes possible. Further, in the present embodiment, since the second pattern  700  is recognized as red, the second pattern  700  does not become remarkably bright, and can exert high contrast with the surroundings. Therefore, the touch recognition higher in accuracy becomes possible. It should be noted that in order to more accurately detect the case in which the phase wrapping no smaller than two cycles occurs, it is preferable to arrange that the first pattern  800  is not displayed when obtaining the image by, for example, blinking the first pattern  800  with a predetermined period. 
     According also to such a third embodiment as described hereinabove, substantially the same advantages as in the first embodiment described above can be exerted. 
     Fourth Embodiment 
     Then, an image recognition unit according to a fourth embodiment of the invention will be described. 
       FIG. 19  is a diagram showing a detecting image used in the image recognition unit according to the fourth embodiment of the invention.  FIG. 20  and  FIG. 21  are each a diagram for explaining a method of the touch recognition. It should be noted that in each of  FIG. 20  and  FIG. 21 , illustrations of the first pattern  800  are omitted for the sake of convenience of explanation. 
     Hereinafter, the image recognition unit according to the fourth embodiment of the invention will be described, wherein the description will be presented with a focus mainly on the differences from the embodiment described above, and the description regarding substantially the same matters will be omitted. 
     The image recognition unit according to the fourth embodiment is substantially the same as the second embodiment described above except the point that the configuration of the detecting image is different. It should be noted that the constituents substantially the same as those of the embodiment described above are denoted by the same reference symbols. 
     As in the stereo-rectified image P 41  shown in  FIG. 19 , in the present embodiment, the second pattern  700  is projected in addition to the first pattern  800  as the detecting image. The second pattern  700  has linear patterns  790  each shaped like a straight line along a direction parallel to the epipolar line EL, and the plurality of (three in the present embodiment) linear patterns  790  is displayed so as to be separated in a vertical direction (a direction crossing the epipolar line EL). Further, between the addresses adjacent to each other, each of the linear patterns  790  is shifted in the vertical direction (i.e., the linear patterns  790  each become discontinuous between the regions). It should be noted that the second pattern  700  can be generated using the visible light, or can also be generated using the NIR light. 
     Also by using such the second pattern  700 , it is possible to accurately distinguish between the case in which the fingertip F 1  is in the contact state and the case of the state in which the phase wrapping occurs. For example, in the stereo-rectified image P 41  in the case of the contact state, as shown in  FIG. 20 , the linear patterns  790  have continuity in the boundary part A between the fingertip F 1  and the screen  900 . In contrast, in the stereo-rectified image P 41  in the case in which the phase wrapping occurs, the linear patterns  790  become discontinuous in the boundary part A as shown in  FIG. 21 . 
     From such a difference between the images, it is possible to accurately distinguish between the contact state and the state in which the phase wrapping occurs. Therefore, the touch recognition higher in accuracy becomes possible. 
     It should be noted that in order to more accurately detect the case in which the phase wrapping no smaller than two cycles occurs, it is preferable to arrange that the first pattern  800  is not displayed when obtaining the image of the second pattern  700  by, for example, blinking the first pattern  800  with a predetermined period. 
     According also to such a fourth embodiment as described hereinabove, substantially the same advantages as in the first embodiment described above can be exerted. 
     Although the image recognition device, the image recognition method and the image recognition unit according to the invention are hereinabove described based on the embodiments shown in the drawings, the invention is not limited to these embodiments. For example, in the image recognition device according to the invention, the configuration of each of the constituents can be replaced with an arbitrary configuration having substantially the same function, and further, it is also possible to add other arbitrary constituents. Further, it is also possible to arbitrarily combine any of the embodiments described above with each other. 
     REFERENCE SIGNS LIST 
     
         
           100  image recognition unit 
           200  projector 
           240 B,  240 G,  240 R liquid crystal display element 
           250  dichroic prism 
           260  projection lens system 
           300  projector 
           310  light source 
           311 B,  311 G,  311 R light source 
           312 B,  312 G,  312 R collimator lens 
           313  light combining section 
           313   a ,  313   b ,  313   c  dichroic mirror 
           314  collecting lens 
           320  scanning section 
           330  movable section 
           331  mirror 
           341 ,  342  shaft section 
           350  drive frame section 
           361 ,  362  shaft section 
           370  support section 
           381 B,  381 G,  381 R liquid crystal display element 
           382  dichroic prism 
           383  projection lens system 
           400  camera 
           410  light receiving unit 
           411  lens system 
           412  imaging element 
           500  image recognition device 
           510  pattern display section 
           520  measurement point determination section 
           530  position detection section 
           700  second pattern 
           701  internal space 
           710  shadowed part 
           790  linear pattern 
           800  first pattern 
           800 A first linear pattern 
           800 B second linear pattern 
           810 A,  810 B first region 
           820 A,  820 B second region 
           900  screen 
         A boundary part 
         AD address pattern 
         B blue light 
         C 1  camera center 
         C 2  angle alteration center 
         EL, EL′ epipolar line 
         F finger 
         F 1  fingertip 
         G green light 
         J 1 , J 2  axis 
         l 1 , l 2 , l 3  straight line 
         La picture light 
         Lb modulated light 
         P 11 , P 21 , P 31 , P 41  stereo-rectified image 
         Pe epipolar point 
         R red light 
         SH shadow 
         x coordinate 
         Σ epipolar plane 
         π 1  image plane 
         π 2  virtual image plane