Abstract:
First imaginary screen outer peripheral line is calculated supplementing one side that is undetected with one side of an outer peripheral line of image light that is calculated, an imaginary screen aspect ratio that is an aspect ratio of an area defined by the first imaginary screen outer peripheral line is calculated, whether the imaginary screen aspect ratio is more vertically oriented than a first ratio or not is determined. When a result of the determination of the imaginary aspect ratio is more vertically oriented than the first ratio, the imaginary screen aspect ratio is changed to second ratio that is different from the first ratio, and the one undetected side is calculated according to the second ratio, and the first imaginary screen outer peripheral line is corrected and a second imaginary screen outer peripheral line is calculated.

Description:
The entire disclosure of Japanese Patent Application No. 2010-207676, filed Sep. 16, 2010 is expressly incorporated by reference herein. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a projector and a control method for a projector. 
     2. Related Art 
     Traditionally, a projector is known which picks up an image of a screen using an image pickup device such as CCD, detects the four sides of a screen frame from the picked-up image, and corrects a projection image according to the screen frame. JP-A-2006-60447 discloses a projector which, when only three or fewer sides of a screen frame are detected, estimates the side (s) that cannot be detected on the basis of the detected sides and corrects an image according to the screen frame. 
     However, in some cases where the aspect ratio of the screen frame is different from the aspect ratio of a projected image from the projector, the position of the side(s) that cannot be detected cannot be estimated (calculated) correctly and the projected image cannot be suitably corrected according to the screen frame. Particularly when an output image from the projector is a wide type with an aspect ratio of 16:10 (or 16:9) while the screen frame has an aspect ratio of 4:3 and the projection distance is short, the projected image cannot be suitably corrected and the projected image may spread out of the screen frame. 
     SUMMARY 
     An advantage of some aspects of the invention is to solve at least a part of the problems described above and the invention can be implemented as the following forms or application examples. 
     Application Example 1 
     According to this application example, a projector for displaying an image on a screen includes: a light source; a light modulation device having a light modulation area for modulating light that exits the light source to effective image light representing an image; an image pickup unit which picks up an image of an area including the screen and the image light and generates a picked-up image; a first outer peripheral line calculating unit which calculates each side of an outer peripheral line of the image light, based on the picked-up image; a second outer peripheral line calculating unit which calculates each side of an outer peripheral line of the screen, based on the picked-up image; an imaginary screen outer peripheral line calculating unit which, when the second outer peripheral line calculating unit detects three of four sides of the outer peripheral line of the screen in the picked-up image, calculates a first imaginary screen outer peripheral line by supplementing one side that is undetected with one side of the outer peripheral line of the image light calculated by the first outer peripheral line calculating unit; an imaginary screen aspect ratio calculating unit which calculates an imaginary screen aspect ratio that is an aspect ratio of an area defined by the first imaginary screen outer peripheral line; an imaginary aspect ratio determining unit which determines whether the imaginary screen aspect ratio is more vertically oriented than a first ratio or not; an imaginary screen outer peripheral line re-calculating unit which, when a result of determination by the imaginary aspect ratio determining unit is more vertically oriented than the first ratio, changes the imaginary screen aspect ratio to a second ratio that is different from the first ratio, calculates the one undetected side according to the second ratio, corrects the first imaginary screen outer peripheral line, and calculates a second imaginary screen outer peripheral line; and a correction image light modulation area calculating unit which calculates a correction image light modulation area that is an area in a part of the light modulation area so as to fit inside the second imaginary screen outer peripheral line. 
     In such a projector, the first outer peripheral line calculating unit calculates each side of an outer peripheral line of image light, based on a picked-up image. The second outer peripheral line calculating unit calculates each side of an outer peripheral line of the screen, based on the picked-up image. The imaginary screen outer peripheral line calculating unit calculates a first imaginary screen outer line by supplementing one undetected side of the outer peripheral line of the screen with one side of the outer peripheral line of the image light. The imaginary screen aspect ratio calculating unit calculates an aspect ratio of an area defined by the first imaginary screen outer peripheral line. The imaginary aspect ratio determining unit determines whether the imaginary screen aspect ratio is more vertically oriented than a first ratio or not. When the result of the determination is more vertically oriented than the first ratio, the imaginary screen outer peripheral line re-calculating unit changes the imaginary screen aspect ratio to a second ratio that is different from the first ratio, calculates the one undetected side according to the second ratio, and calculates a second imaginary screen outer peripheral line. The correction image light modulation area calculating unit calculates a correction image light modulation area so as to fit inside the second imaginary screen outer peripheral line. Thus, even when one side of the screen cannot be detected and the aspect ratio of the screen is different from the aspect ratio of the light modulation area of the projector, the projected image can be corrected to fit within the screen. 
     Also, since an image such that the aspect ratio of the light modulation area is maintained is projected on the screen, distortion of the projected image can be avoided. 
     Moreover, since an image is projected in such a way that the image is inscribed within the second imaginary screen outer peripheral line, visibility of the projected image is improved. 
     Also, when an image is projected on a commercially available screen with an aspect ratio of 4:3 from the projector in which the light modulation area has an aspect ratio of 16:10, even if one side of the screen cannot be detected, the projected image can be corrected to fit within the screen. 
     Moreover, even when one side of the screen cannot be detected and the aspect ratio of the screen is different from the aspect ratio of the light modulation area of the projector, the projected image can be corrected to fit within the screen. 
     Furthermore, in the case where the above projector and a control method for the projector are constructed using a computer provided in the projector, the above form and application example can be configured in the form of a program for realizing the functions thereof, or a recording medium or the like in which the program is recorded in a computer-readable manner. As the recording medium, various media readable by the computer can be used such as flexible disk, hard disk, CD-ROM (compact disk read only memory), DVD (digital versatile disk), Blu-ray Disc (trademark registered), magneto-optical disc, non-volatile memory card, internal storage device of the projector (semiconductor memory such as RAM (random access memory) or ROM (read only memory)), and external storage device (USB (universal serial bus) memory). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
         FIG. 1  is an explanatory view showing a projector according to an embodiment, as viewed from above. 
         FIG. 2  is a block diagram showing the schematic configuration of the projector. 
         FIG. 3  is a flowchart of image correction processing in the projector. 
         FIGS. 4A and 4B  are explanatory views of calculation of an imaginary screen frame.  FIG. 4A  is an explanatory view showing a full projection area, a screen frame and an image pickup area.  FIG. 4B  is an explanatory view showing the screen frame, an image pickup area and an imaginary screen frame. 
         FIGS. 5A to 5C  are explanatory views of re-calculation of an imaginary screen frame and formation of a correction image.  FIG. 5A  is an explanatory view showing a screen frame and an imaginary screen frame.  FIG. 5B  is an explanatory view showing the screen frame and a re-calculated imaginary screen frame.  FIG. 5C  is an explanatory view showing the screen frame, the re-calculated imaginary screen frame and a correction image. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Hereinafter, embodiments will be described. 
     Embodiments 
     In this embodiment, a projector which has an image pickup device and corrects an image to fit inside an outer peripheral line of an external screen (also referred to as a “screen frame”) will be described. 
       FIG. 1  is an explanatory view showing a projector according to this embodiment, as viewed from above. As shown in  FIG. 1 , a projection system (projection lens)  150  and an image pickup unit (image pickup device)  180  are installed on the front side of the body of a projector  100  in a way that the projection system  150  and the image pickup unit  180  are next to each other. Here, a projection angle of view that is the angle of view at which the projection system  150  projects an image is illustrated as θ 1 , and the center line of the projection angle of view is illustrated as H 1 . An image pickup angle of view that is the angle of view at which the image pickup unit  180  picks up an image is illustrated as θ 2  (θ 2 &gt;θ 1 ), and the center line of the image pickup angle of view is illustrated as H 2 . The image pickup unit  180  is installed in an inclined state toward the projection system  150  by an angle θ 3  in relation to the direction of the optical axis of the projection system  150  (that is, the direction of the center line H 1 ). 
     In this manner, the projection system  150  and the image pickup unit  180  are installed at different positions. Therefore, across a distance L from the projector  100  to a point of intersection A between the projection angle of view and the image pickup angle of view, the image pickup unit  180  cannot pick up an image of the vicinity of the right end of an image projected from the projection system  150 . If the difference between the projection angle of view θ 1  and the image pickup angle of view θ 2  is small, the range where image pickup is unavailable increases. 
       FIG. 2  is a block diagram showing the schematic configuration of the projector  100  according to the embodiment. The internal configuration of the projector  100  will be described with reference to  FIG. 2 . The projector  100  projects image light representing an image and displays the image (hereinafter referred to as a “projected image”) on a screen such as a screen SC. The screen SC has an aspect ratio of 4:3. 
     The projector  100  has an A/D converter unit  110 , an internal memory  120 , a liquid crystal panel  130  and a light crystal panel driving unit  132  as an image forming panel unit, an illumination system  140  as a light source, the projection system  150 , a CPU  160 , an operation accepting unit  170 , the image pickup unit  180  as an image pickup section, a picked-up image memory  182  and the like. Here, the internal memory  120 , the liquid crystal panel driving unit  132 , the CPU  160 , the operation accepting unit  170  and the picked-up image memory  182  are connected with each other via a bus  102 . 
     The A/D converter unit  110  has various image input terminals for connecting with an external image supply device (not shown) such as a personal computer, video reproduction device, memory card, USB storage or digital camera, via a cable. An image signal is inputted to the A/D converter unit  110  from the image supply device. The A/D converter unit  110  performs A/D conversion as needed and outputs a digital image signal. 
     In the internal memory  120 , a computer program functioning as an image processing unit  122  is stored. The image processing unit  122  adjusts the display state of the image (for example, luminance, contrast, synchronization, tracking, color density, color tone and the like) for the digital image signal outputted from the A/D converter  110 , and outputs the digital image signal to the liquid crystal panel driving unit  132 . The image processing unit  122  has an image correction unit  123  which corrects the image to fit within the screen SC. 
     The liquid crystal panel driving unit  132  drives the liquid crystal panel  130  as a light modulation device, based on the digital image signal inputted via the image processing unit  122 . The liquid crystal panel  130  forms an image for modulating illuminating light cast from the illumination system  140  to effective image light representing an image, in a light modulation area on the surface (also referred to as a “panel surface”) of the liquid crystal panel  130 . In this embodiment, the light modulation area is assumed to be coincident with the liquid crystal panel  130 . However, the light modulation area may be a smaller area than the entire panel surface of the liquid crystal panel  130 . The liquid crystal panel  130  has an aspect ratio of 16:10. 
     The projection system  150  is installed on the front side of the casing of the projector  100  and projects the light modulated to the image light by the liquid crystal panel  130 , in an enlarged state. 
     The operation accepting unit  170  has plural keys and the like for giving various instructions to the projector  100 . The keys provided in the operation accepting unit  170  may include a “power key” for turning power on and off, an “input switch key” for switching inputted image signals, a “menu key” for switching between display and non-display of a menu screen on which various settings are performed, a “cursor key” used to move a cursor in the menu screen, a “decision key” for deciding various settings, an “image correction key” for correcting a projected image to fit within the frame of the screen SC, and the like. As the user operates the operation accepting unit  170 , the operation accepting unit  170  outputs control information corresponding to the user&#39;s operation content to the CPU  160  via the bus  102 . The operation accepting unit  170  may also be configured with a remote control signal receiving unit (not shown) and a remote controller capable of remote control. In this case, the remote controller issues an operation signal of infrared rays corresponding to the user&#39;s operation content, and the remote control signal receiving unit receives this operation signal and transmits the operation signal to the CPU  160  as control information. 
     The CPU  160  reads out and executes the computer program as the image processing unit  122  from the internal memory  120 , thus projecting an image on the screen SC or performing image processing such as image correction processing, which will be described later. The CPU  160  also generally controls operation of each unit within the projector  100 . 
     The image pickup unit  180  has a CCD camera and generates a picked-up image. The picked-up image generated by the image pickup unit  180  becomes stored in the picked-up image memory  182  via the internal memory  120 . The image pickup unit  180  can also have another image pickup device instead of the CCD camera. 
     Next, image correction processing in which the projector  100  corrects a projected image to fit inside the outer peripheral line of the screen SC (hereinafter referred to as a “screen frame SF”) will be described.  FIG. 3  is a flowchart of the image correction processing in the projector  100 . The CPU  160  carries out the image correction processing according to a program provided in the image correction unit  123 . 
     When the image correction key provided on the operation accepting unit  170  is pressed, the CPU  160  causes a predetermined detection pattern image to be projected which is for detecting the full projection area on the liquid crystal panel  130 , and the image pickup unit  180  picks up the projected image (step S 101 ). The CPU  160  analyzes the picked-up image and detects the full projection area and the screen frame SF (step S 102 ). The CPU  160  which detects the full projection area is equivalent to the first outer peripheral line calculating unit. The CPU  160  which detects the screen frame SF is equivalent to the second outer peripheral line calculating unit. As a method for detecting the full projection area and the screen frame SF, a known method is used (see, for example, JP-A-2006-60447). 
     The CPU  160  determines whether all the sides of the screen frame SF are detected or not (step S 103 ). If all the sides of the screen frame SF are not detected (step S 103 : NO), the CPU  160  calculates an imaginary screen frame using a side of the outer peripheral line of the full projection area in place of the side that cannot be detected (step S 104 ). This imaginary screen frame is equivalent to the first imaginary screen outer peripheral line. The CPU  160  in this case is equivalent to the imaginary screen outer peripheral line calculating unit. 
     Now, the calculation of the imaginary screen frame will be described with reference to the drawings. 
       FIGS. 4A and 4B  are explanatory views for the calculation of the imaginary screen frame.  FIG. 4A  is an explanatory view showing the full projection area, the screen frame SF and the image pickup area.  FIG. 4B  is an explanatory view showing the screen frame SF, the image pickup area and the imaginary screen frame. 
     In  FIG. 4A , a full projection area PF is illustrated as including the screen frame SF. That is, a predetermined detection pattern image is projected to include the screen frame SF. Here, the screen frame SF has an aspect ratio of 4:3 and the full projection area PF has an aspect ratio of 16:10. A right side SFr of the screen frame SF and a right side PFr of the full projection area PF are not included in an image pickup area CI. In this state, the CPU  160  cannot detect one side (the right side SFr) of the screen frame SF. However, the CPU  160  can calculate the right side PFr of the full projection area PF as the right end position of the liquid crystal panel  130 . 
       FIG. 4B  shows a state where an imaginary screen frame iSF 1  is calculated. The imaginary screen frame iSF 1  is indicated by a chain dotted line. Three sides (left side, top side and bottom side) of the imaginary screen frame iSF 1  are at the same positions as the three sides detected in the screen frame SF. The remaining one side (right side) is at the position of the right side PFr of the full projection area PF. The imaginary screen frame iSF 1  is calculated in this manner. 
     Back to  FIG. 3 , the CPU  160  determines whether the aspect ratio (horizontal:vertical) of the calculated imaginary screen frame iSF 1  is more vertically oriented than 16:10 or not (step S 105 ). The CPU  160  in this case is equivalent to the imaginary screen aspect ratio calculating unit and the imaginary aspect ratio determining unit. If the aspect ratio of the imaginary screen frame iSF 1  is more vertically oriented than 16:10 (step S 105 : YES), the CPU  160  determines that the aspect ratio of the actual screen SC (screen frame SF) is 4:3, and re-calculates an imaginary screen frame iSF 2  with an aspect ratio of 4:3 based on the three sides detected in the screen frame SF (step S 106 ). The imaginary screen frame iSF 2  is equivalent to the second imaginary screen outer peripheral line. The CPU  160  in this case is equivalent to the imaginary screen outer peripheral line re-calculating unit. 
     Then, the CPU  160  forms a correction image to fit within a maximum width of the calculated imaginary screen frame (here, imaginary screen frame iSF 2 ) while maintaining the aspect ratio (16:10) of the liquid crystal panel  130  (step S 107 ). The CPU  160  in this case is equivalent to the correction image light modulation area calculating unit. For the correction image forming processing by the correction image light modulation area calculating unit, a known processing method is used (see, for example, JP-A-2006-60447). Then, the image correction processing ends. 
     Now, the re-calculation of the imaginary screen frame and the formation of the correction image will be described with reference to the drawings. 
       FIGS. 5A to 5C  are explanatory views for the re-calculation of the imaginary screen frame and the formation of the correction image.  FIG. 5A  is an explanatory view showing the screen frame SF and the imaginary screen frame iSF 1 .  FIG. 5B  is an explanatory view showing the screen frame SF and the re-calculated imaginary screen frame iSF 2 .  FIG. 5C  is an explanatory view showing the screen frame SF, the re-calculated imaginary screen frame iSF 2  and the correction image. 
       FIG. 5A  shows a state where the imaginary screen frame iSF 1  is calculated.  FIG. 5B  shows the state of the re-calculated imaginary screen frame iSF 2 . The imaginary screen frame iSF 2  has an aspect ratio of 4:3 and therefore has a shape that fits within the screen frame SF. In  FIG. 5C , a correction image RIF maintaining the aspect ratio (16:10) of the liquid crystal panel  130  is formed in the imaginary screen frame iSF 2 . 
     Back to  FIG. 3 , if the aspect ratio of the imaginary screen frame iSF 1  is not more vertically oriented than 16:10 (step S 105 : NO), the CPU  160  shifts to step S 107  without re-calculating the imaginary screen frame, and forms the correction image RIF to fit longitudinally or laterally within the maximum width of the calculated imaginary screen frame (here, the imaginary screen frame iSF 1 ) while maintaining the aspect ratio (16:10) of the liquid crystal panel  130 . Then, the image correction processing ends. 
     If all the sides of the screen frame SF are detected (step S 103 : YES), the correction image RIF is formed to fit longitudinally or laterally within the maximum width of the detected screen frame SF while maintaining the aspect ratio (16:10) of the liquid crystal panel  130  (step S 108 ). Then, the image correction processing ends. 
     As described above, the projector  100  corrects the correction image RIF to fit within the screen frame SF. 
     The above embodiment has the following effects. 
     (1) If the aspect ratio of imaginary screen frame iSF 1  is more vertically oriented than 16:10, the projector  100  re-calculates the imaginary screen frame iSF 2  on the assumption that the aspect ratio is 4:3. Then, the correction image is formed to fit inside the imaginary screen frame iSF 2  with the aspect ratio of 4:3. Therefore, even when one side of the screen frame SF cannot be detected and the aspect ratio of the screen frame SF is different from the aspect ratio of the liquid crystal panel  130  of the projector  100 , the projected image can be corrected to fit within the screen frame SF. Thus, spreading of the projected image from the screen frame SF with the aspect ratio of 4:3 can be avoided and the user can visually recognize a preferable projected image. 
     (2) The projector  100  forms the correction image maintaining the aspect ratio of the liquid crystal panel  130  in relation to the imaginary screen frames iSF 1  and iSF 2 . Therefore, since the image maintaining the aspect ratio of the liquid crystal panel  130  is projected on the screen SC, distortion of the projected image can be avoided. Thus, the user can visually recognize a preferable projected image. 
     (3) The projector  100  calculates the correction image with the longitudinal or lateral maximum width of (that is, inscribed within) the imaginary screen frames iSF 1  and iSF 2  while maintaining the aspect ratio of the liquid crystal panel  130  in relation to the imaginary screen frames iSF 1  and iSF 2 . Thus, the image is projected with the maximum width within the screen frame SF and therefore visibility of the projected image is improved. 
     (4) When the aspect ratio of the imaginary screen frame iSF 1  is not more vertically oriented than 16:10, the projector  100  forms the correction image to fit inside the imaginary screen frame iSF 1 . Thus, when one side of the screen frame SF cannot be detected and the aspect ratio of the screen frame SF is more horizontally oriented than 4:3, the projected image is corrected with the longitudinal or lateral maximum width to fit within the imaginary screen frame iSF 1  on the assumption that the screen frame SF has the aspect ratio of 16:10 or is more horizontally oriented. Therefore, the user can visually recognize a preferably projected image maintaining the aspect ratio of the liquid crystal panel  130 . 
     (5) When all the sides of the screen frame SF are detected, the projector  100  can corrects the projected image maintaining the aspect ratio of the liquid crystal panel  130  to fit inside the detected screen frame SF. Therefore, the user can visually recognize a preferable projected image. 
     (6) In the projector  100 , the first ratio is 16:10 and the second ratio is 4:3. Thus, when an image is projected on a commercially available screen SC with an aspect ratio of 4:3 from the projector  100  having the liquid crystal panel  130  with an aspect ratio of 16:10, even if one side of the screen cannot be detected, the projected image can be corrected to fit within the screen, which is advantageous. 
     (7) Since the projector  100  performs image correction processing, the image pickup angle of view of the image pickup unit  180  need not be an unnecessarily wide angle in relation to the projection angle of view of the projection system  150 . That is, the image pickup device such as a CCD camera used in the image pickup unit  180  need not have an unnecessarily wide angle. Therefore, the degree of freedom in component selection at the time of product designing. Moreover, the allowable range of the installation angle of the image pickup unit  180  can be expanded. 
     The invention is not limited to the above embodiment and can be carried out with various changes, improvements and the like. Modifications will be described hereinafter. 
     Modification 1 
     The first ratio is 16:10 in the embodiment, but may also be 16:9. 
     Modification 2 
     The image processing unit  122  is a computer program in the embodiment, but may also be configured with a circuit device (not shown) which performs image processing. 
     Modification 3 
     In the embodiment, the transmission-type liquid crystal panel  130  is used as the light modulation device. However, a reflection-type light modulation device such as a reflection-type liquid crystal panel can also be used. Moreover, a micro mirror array device or the like which modulates light exiting a light source by controlling the exit direction of the incident light for each micro mirror as a pixel can be used.