Abstract:
In the usage of table projection of a projection type display, depending upon a sitting position of a participant of a conference, the participant views an image projected upon a table as an inversion image turned upside down, resulting in poor visual recognition. In order to improve visual recognition, images are rotated, synthesized and displayed in accordance with the viewing direction of each participant. More specifically, the projection type display is provided with a two-image synthesizing unit for synthesizing two images obtained by processing an input image by two image rotation units for rotating the input image by a first angle and a second angle different from the first angle, into one image on a screen. The projection type display is also provided with an image rotation unit and an image inversion unit for two-image display on a screen.

Description:
INCORPORATION BY REFERENCE 
       [0001]    The present application claims priority from Japanese Patent Application JP2009-083961, filed on Mar. 31, 2009, the content of which is hereby incorporated by reference into this application. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to techniques of providing a projection type display for projecting images. 
         [0003]    In recent years, a projection type display including a projector provides a variety of usage types. In one usage type, an image is projected upon a generally vertical flat plane such as a general screen, a room wall and a blackboard. In addition to this usage type of projecting an image upon a generally vertical flat plane, in another usage type, a projection type display can project an image upon a generally horizontal flat plane such as a desk, as described in JP-A-2008-209670. 
       SUMMARY OF THE INVENTION 
       [0004]    When a person viewing (viewer) views an image projected by a projection type display (projected image) on a generally vertical flat plane including a general screen, there arises no problem because an up-down direction of the projected image coincides with an up-down direction of the viewer. 
         [0005]    However, the projection type display described in the above-described JP-A-2008-209670 can project an image on a generally horizontal flat plane such as a table. A problem associated with this display will be described with reference to  FIG. 3 .  FIG. 3  is a diagram illustrating a usage type (such as conference) of projecting an image on a table. 
         [0006]    In  FIG. 3 , reference numeral  116  represents a projection plane (table surface), reference numeral  101  represents a projection type display, reference numeral  201  represents a projected image on the table, and reference numerals  301  and  302  represent viewers. In the usage of table projection, viewers surround in many cases the projected image as illustrated in  FIG. 3 . In such cases, a direction along which the projected image  201  is viewed changes with the position of each viewer. For example, assuming that the up direction of the projected image  201  is right in the drawing, the viewer  301  views the projected image  201  along the coincident up-down direction (a shift of 0 degree between the up-down direction as viewed by the viewer  301  and the up-down direction of the projected image  201 ), whereas the viewer  302  views the projected image  201  upside down (a shift of 180 degrees between the up-down direction as viewed by the viewer  302  and the up-down direction of the projected image  201 ), resulting in poor visual recognition. 
         [0007]    This point is not considered at all for the projection type display described in the above-described JP-A-2008-209670. 
         [0008]    An object of the present invention is to provide a projection type display capable of projecting an image providing good visual recognition to each of viewers even if the viewers surround the projected image on a table during a conference or the like. 
         [0009]    According to the present invention, a projection type display is provided with an image processing unit including: a first image rotation unit for rotating the input image by a first angle; a second image rotation unit for rotating the input image by a second angle; and a two-image synthesizing unit for synthesizing a first output image from said first image rotation unit and a second output image from said second image rotation unit into one image. 
         [0010]    According to the present invention, a projection type display can be realized which can project an image providing good visual recognition to each of viewers even if the viewers surround the projected image on a table during a conference or the like. 
         [0011]    Other objects, features and advantages of the invention will become apparent from the following description of the embodiments of the invention taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a block diagram of a projection type display according to a first embodiment of the present invention. 
           [0013]      FIGS. 2A and 2B  are diagrams illustrating projected images. 
           [0014]      FIG. 3  is a diagram illustrating a usage type of projecting an image on a table. 
           [0015]      FIGS. 4A to 4F  are diagrams illustrating display functions of a projection type table display according to a second embodiment of the present invention. 
           [0016]      FIG. 5  is a block diagram of the projection type table display of the second embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    Best modes for carrying out the present invention will now be described with reference to the accompanying drawings. In each drawing to be described below, elements having common functions are represented by using identical reference numerals, and for the element described once, duplicate description is omitted. 
       First Embodiment 
       [0018]      FIG. 1  is a block diagram of a projection type display of the first embodiment. In  FIG. 1 , reference numeral  101  represents the project type display, a central processing unit (abbreviated to “CPU” in the following)  102  performs an overall control of the projection type display, a ROM (including a flash ROM)  103  stores programs for controlling CPU  102 , a RAM  104  stores calculation results and the like to be used by CUP  102  when programs are executed, a nonvolatile memory  105  stores a variety of information, an input terminal  110  receives a video signal (not shown) from an external, and an input signal processing unit  111  executes a predetermined process for a video signal input from the input terminal  111 . 
         [0019]    The input signal processing unit  111  analog-digital converts the input signal into digital data, and outputs the digital data to a first image rotation unit  106  and a second image rotation unit  107 . The first image rotation unit  106  rotates an input image by a first angle (an image rotated by the first image rotation unit is called herein a first rotation display image). The second image rotation unit  107  rotates an input image by a second angle different from the first angle (an image rotated by the second image rotation unit is called herein a second rotation display image). 
         [0020]    A two-image synthesizing unit  108  synthesizes the first and second rotation display images rotated and output from the first and second image rotation units  106  and  107  into one image. An image processing unit  109  performs scaling including image magnification, image reduction, geometrical distortion correction and the like of an image signal output from a two-image synthesizing unit  108 . 
         [0021]    In this embodiment, although the image magnification and reduction are performed by the image processing unit  109  after two-image synthesis, the image magnification and reduction may be performed in advance by the first and second image rotation units  106  and  107 , or the image magnification and reduction may be performed by the two-image synthesizing unit  108  relative to the first and second rotation images after image rotation output from the first and second image rotation units  106  and  107 . Alternatively, the image magnification and reduction may be preformed by an arbitrary combination of the first and second image rotation units  106  and  107 , two-image synthesizing unit  108  and image processing unit  109 . 
         [0022]    Reference numeral  112  represents a driver circuit, reference numeral  113  represents an illumination optical block, reference numeral  114  represents a liquid crystal panel, reference numeral  115  represents a projection lens block, and reference numeral  116  represents a projection plane. The illumination optical block  113  converts randomly polarized light from a light source (not shown) into linearly polarized light with a polarization conversion device (not shown), and applies the linearly polarized light to the liquid crystal panel  114 . The liquid crystal panel  114  controls a transmission amount of light applied from the illumination optical block  113 . In accordance with image data output from the image processing unit  109 , the driver circuit  112  controls a transmissivity of each pixel of the liquid crystal panel  114  to thereby form an image. In this example, the liquid crystal panel  114  is constituted of a laterally elongated LCD panel of high resolution. The projection lens block  115  magnifies and projects light (image) transmitted through the liquid crystal panel  114  so that an image formed on the liquid crystal panel  114  is projected upon the projection plane  116 . An operation unit  117  controls the projection type display  101  by a plurality of operation buttons disposed on the housing of the projection type display and by an infrared remote control signal (hereinafter abbreviated to “IR remote signal”) from a remote controller. 
         [0023]      FIGS. 2A and 2B  are diagrams illustrating projected images. Reference numeral  201  represents a displayed image, reference numeral  202  represents a first rotation display image, and reference numeral  203  represents a second rotation display image.  FIG. 2A  illustrates a display example of two-image rotation display projected on a generally horizontal flat plane such as a table, and  FIG. 2B  illustrates a display example of one-image on a screen projected on a generally vertical flat plane such as a general screen. 
         [0024]    Description will be made first on two-image rotation display to be used for projection upon a generally horizontal flat plane such as a table. 
         [0025]    A video signal input from the input terminal  110  is analog-digital converted by the input signal processing unit  111 , and the converted digital data is input to the first image rotation unit  106  and second image rotation unit  107 . The image input to the first image rotation unit  106  is rotated by a first angle (90 degrees in the clockwise direction) to form the first rotation display image  202 . 
         [0026]    The image input to the second image rotation unit  107  is rotated by a second angle (270 degrees in the clockwise direction) to form the second rotation display image  203 . The video signals subjected to rotation are input to the two-image synthesizing unit  108  to synthesize two images into one image. In this embodiment, synthesizing into one image by the two-image synthesizing unit  108  is performed in such a manner that the rotation display images  202  and  203  are disposed on right and left screen areas, respectively. 
         [0027]    Next, the video signal synthesized by the two-image synthesizing unit  108  is input to the image processing unit  109  which in turn performs scaling including image magnification, image reduction, geometrical distortion correction and the like and outputs the processed video signal to the driver circuit  112 . In accordance with this input signal, the driver circuit  112  controls the liquid crystal panel  114  to display a projected image such as that shown in  FIG. 2A . 
         [0028]    An input display image is generally a laterally elongated image. Since the liquid crystal display  114  is also laterally elongated, the input image can be displayed largest if the first angle is set to 90 degrees in the clockwise direction and the second angle is set to 270 degrees in the clockwise direction as described above. Since the first rotation display image  202  and second rotation display image  203  are synthesized so as to contact the upper ends thereof, even if a number of viewers view the projected image  201  as shown in  FIG. 3 , each viewer views either the first rotation display image  202  or second rotation display image  203  which is nearer to the viewer so that a shift between the up-down direction of each viewer and the up-down direction of the rotation display image  202  or  203  is 90 degrees or smaller. 
         [0029]    In conventional one-image on a screen, a number of viewers have poor visual recognition having a shift of 90 degrees or larger between the up-down direction of a viewer and the up-down direction of a projected image. This problem is eliminated by two-image rotation display such as shown in  FIG. 2A . 
         [0030]    Description will be made next on one-image display on a screen to be used for projection upon a generally vertical flat plane such as a screen. A video signal input from the input terminal  110  is analog-digital converted by the input signal processing unit  111 , and the converted digital data is input to the first image rotation unit  106 . In this case, CPU  102  controls the first image rotation unit  106  to output the input signal without rotation, and controls the two-image synthesizing unit  108  to output only the image from the first image rotation unit  106 , without using the video signal input to the second image rotation unit  107 . The video signal output from the two-image synthesizing unit  108  is input to the image processing unit  109  which in turn performs scaling including image magnification, image reduction, geometrical distortion correction and the like of one-image display, and outputs the processed video signal to the driver circuit  112 . In accordance with this input signal, the driver circuit  112  controls the liquid crystal panel  114  to display a projected image such as shown in  FIG. 2B . 
         [0031]    A user can select either two-image rotation display illustrated in  FIG. 2A  or one-image display illustrated in  FIG. 2B . This may be realized by sending a display switching control signal from the operation unit  117  to CPU  102  in response to activation of an operation button, or by sending an IR remote signal from a remote controller in response to activation of the remote controller by a user and sending a display switching control signal from the operation unit  117  to CPU  102 . Alternatively, an angle sensor or the like may be mounted in the projection type display  101 , and if it is judged that the projection type display  101  projects an image upon a generally vertical flat plane such as a table, two-image rotation display illustrated in  FIG. 2A  is automatically conducted. 
         [0032]    The angle sensor may detect and judge image projection upon a generally horizontal flat plane or upon a generally vertical flat plane, by detecting an installation angle of the projection type display  101  or a posture angle of the projection type display  101 . 
         [0033]    Alternatively the angle sensor may detect and judge image projection upon a generally horizontal flat plane or upon a generally vertical flat plane, by detecting an angle of a projection direction of a light beam emitted from the lens or an angle of the lens. 
         [0034]    As described so far, it is possible to provide a projection type display capable of projecting an image allowing any viewer to have good visual recognition, by rotating each image in a projected image. 
       Second Embodiment 
       [0035]    Next, with reference to  FIGS. 4A to 4F  and  FIG. 5 , description will be made on another embodiment of a projection type table display of the present invention. The projection type table display of this embodiment is configured as having a block diagram different from that illustrated in  FIG. 1 , and has a simple structure because image rotation is restricted to 90 degrees. Although elements in the drawings will be described in detail, for an element having an identical reference numeral to that in  FIG. 1 , duplicate description is omitted. 
         [0036]    Prior to describing the block structure illustrated in  FIG. 5 , a projected image display function of the embodiment will be described with reference to  FIGS. 4A to 4F .  FIG. 4A  is a diagram illustrating a fundamental image display of the embodiment. The projection type display of the embodiment is a transmission type liquid crystal projector or the like, and can shift an image and display it in a predetermined area in a projection area of the projection type table display. As illustrated in  FIG. 4A , this image area can be set to a predetermined position in the projection area, by designating projection position coordinate values by using the upper left corner of the image area as an image area reference. Image shift display can be performed optically by incorporating known technologies. 
         [0037]    In the following description, it is assumed that an image in an image area a user at a user position A in  FIG. 4A  views is sent as an input image from an upper level apparatus connected to the projection type display. 
         [0038]    The display of the embodiment is a transmission type liquid crystal projector or the like, and can perform optical zooming of a projected image by adjusting the projection lens.  FIG. 4B  illustrates optical zooming. As a video signal of an input image corresponding to the image area in  4 A is input, an image optically magnified to the whole projection area is displayed by the zooming function. 
         [0039]    The projection type table display of the embodiment is used not only at the user position illustrated in  FIGS. 4A and 4B  but also at a user position B illustrated in  FIG. 4C . In the latter case, the input image is rotated by 90 degrees in the clockwise direction and displayed in the projection area. As described above, the display position is adjusted by setting the projection position coordinates of the image area reference. The positions along the depth direction and right/left direction as viewed from the user at the user position B are adjusted in this manner so that erection image display and magnification image display can be performed. 
         [0040]      FIG. 4D  is a diagram illustrating image display relative to a user at a user position D opposite to the user position B illustrated in  FIG. 4C . The projection type table display of the embodiment rotates an input image by 90 degrees in the counter clockwise direction or by 270 degrees in the clockwise direction and displays the rotated image in the projection area so as to allow the user at the user position D to view an erection image. Similar to the example illustrated in  FIG. 4C , it is possible to adjust the display position of an image and magnify the image. 
         [0041]    Although the details will be described later, in this embodiment, a rotation process of an input image is performed by a combination of a 90-degree rotation process and an inversion process. It is therefore possible to simplify the image rotation unit. 
         [0042]    Although not shown, the projection type table display of the embodiment may be used by a user at a position opposite to the user position A illustrated in  FIG. 4A . In this case, although an input image may be rotated by 180 degrees in the clockwise direction and displayed in the projection area, in this embodiment this process is realized by performing an inversion process of an input image. 
         [0043]    As illustrated in  FIGS. 4A ,  4 C and  4 D, the projection type table display of the embodiment performs the rotation process of an input image in accordance with the user position (user positions A, B and D) and displays the rotated image in the image area. In order to realize this, a user position detection unit is provided, and in accordance with a detection result an input image is rotated, the details of which will be described later. 
         [0044]    The case wherein a user views an image projected by the projection type table display of the embodiment along one direction has been described above. In the following, description will be made on the case wherein a plurality of users view an image along opposite two directions similar to the first embodiment, with reference to  FIG. 4E . 
         [0045]    If users are at the user positions B and D along a long side direction of the projection area of the projection type table display of the embodiment, similar to the first embodiment two-image display is performed to provide users with an erection image. For example, in order to allow a user at the user position B to view an erection image, an input image is rotated by 90 degrees in the clockwise direction and displayed in the image area in front of the user position B, whereas in order to allow a user at the user position D to view an erection image, an input image is displayed by performing an inversion process for the image projected in front of the user position B. 
         [0046]    By displaying two images of erection display and inversion display along the up/down direction, users at the opposite user positions B and D can view an erection image providing good visual recognition of image information. In this case, even users at the user positions A and C can view image information laterally so that better visual recognition of image information can be provided more than viewing an inversion image. 
         [0047]    Users positioned along the long side direction of the projection area have been described with reference to  FIG. 4E . Users positioned along the short side direction of the projection area will be described with reference to  FIG. 4F . In this case, two images of erection display and inversion display are displayed side by side. With this two-image display, users at the user positions A and C can view an erection image providing good visual recognition of image information, In this case, even users at the user positions B and D can view image information laterally so that better visual recognition of image information can be provided more than viewing an inversion image. 
         [0048]    As described above, the user position detection unit detects user positions A, B, C and D of users, to select an image display direction and display two images of erection display and inversion display side by side or along an up-down direction. It is therefore possible to optimize image information in accordance with the user positions of users. 
         [0049]    Two-image display is preferably realized along the long side direction of the projection area. 
         [0050]    The embodiment will be described in detail with reference to the block diagram illustrated in  FIG. 5 . 
         [0051]    A block having an identical reference numeral to that in  FIG. 1  has a similar function, and so duplicate description is omitted. 
         [0052]    Description will be made first on the case wherein one erection image is projected as illustrate in  FIGS. 4A and 4B . Image information sent from an upper level apparatus is input from an input terminal  110 , and subjected to predetermined signal processing by an input signal processing unit  111 . In the case of  FIGS. 4A and 4B , since image rotation is not performed, the image information is stored in an image memory  118  without involving an image rotation unit  119  and an image inversion unit  120 . The image information stored in the image memory  118  is input from a driver circuit  112  to a liquid crystal panel  114  to display a projected image. 
         [0053]    In this case, the driver circuit  112  adjusts an image display position by controlling read timings of the image information stored in the image memory  118 . Optical zooming of the projected image is performed by controlling a projection lens block  115  to project the image upon the whole projection area, as shown in  FIG. 4B . 
         [0054]    Description will be made next on rotation display of image information as illustrated in  FIG. 4C . As an image along a direction illustrated in  FIGS. 4A and 4B  is input via the input terminal  110  and input signal processing unit  111 , the image rotation unit  119  rotates the image by 90 degrees in the clockwise direction, and the rotated image is stored in the image memory  118 . For the image information stored in the image memory  118 , the driver circuit  112  adjusts an image display position, and the projection lens block  115  performs optical zooming to project the image. 
         [0055]    In the example described above, the image display position and display size are adjusted by the drive circuit  112  and projection lens block  115 . Instead, a plurality of image memories  118  and liquid crystal panels  114  corresponding in number to the number of projection areas may be prepared. Image information is stored in the image memory  118  corresponding to the image display position. Image information subjected to a magnification/reduction process may also be stored in the corresponding image memory  118 . 
         [0056]      FIG. 4D  illustrates image information rotated by 270 degrees in the clockwise direction (by 90 degrees in the counter clockwise direction) as described above. The image rotation unit  119  of the embodiment is a unit for performing a rotation process by 90 degrees in the clockwise direction. Therefore, although a rotation unit for rotating by 270 degrees in the clockwise direction (by 90 degrees in the counter clockwise direction) may be provided, a processing scale becomes large. In this embodiment, therefore, a rotation process of rotating by 270 degrees in the clockwise direction (by 90 degrees in the counter clockwise direction) is executed in the following manner. 
         [0057]    First, the image information is subjected to a process of rotating by 90 degrees in the clockwise direction by the image rotation unit  119 , and the rotated image information is stored in an unused area of the image memory  118 . Next, the image information rotated by 90 degrees in the clockwise direction is read to the image inversion process unit  120  which performs an image inversion process and stores the processed image in a predetermined area of the image memory  118 . For the image information stored in the image memory, the drive circuit  112  adjusts an image display position, and the projection lens block  115  performs optical zooming to project the image. 
         [0058]    The image inversion process can be realized by changing the order of read/write addresses of the image memory  118  or inverting bit trains. Therefore, the image inversion process can be realized by a circuit scale smaller than that for the image rotation process. 
         [0059]    In the example illustrated in  FIG. 4E , by performing a similar process to that for the image information illustrated in  FIG. 4C , image information rotated by 90 degrees in the clockwise direction is stored in a predetermine area of the image memory. Thereafter, the image information in the image memory is read to the image inversion unit  120  which performs the image inversion process and stores the processed image information in a predetermined area of the image memory  118  for two-image display together with the image information rotated by 90 degrees in the clockwise direction, along the up/down direction. For the image information stored in the image memory, the drive circuit  112  adjusts an image display position, and the projection lens block  115  performs optical zooming to project the image. 
         [0060]    In the example illustrated in  FIG. 4F , since image is not rotated as in the example illustrated in  FIG. 4A , image information is stored in a predetermined area of the image memory  118  without involving the image rotation unit  119  and image inversion unit  120 . The image information not subjected to the rotation process is read to the image inversion unit  120  which performs the image inversion process and writes the inverted image information in a predetermined area of the image memory  118 . In this manner, two images of erection display and inversion display are displayed in the projection area side by side along the long side direction. 
         [0061]    The user detecting unit  121  detects positions of users with a sensor or the like, and in accordance with a detection result, one of image displays illustrated in  FIGS. 4A to 4F  is performed. The user detection unit  121  may be the operation unit such as a remote controller for inputting a position of each user. 
         [0062]    It should be further understood by those skilled in the art that although the foregoing description has been made on embodiments of the invention, the invention is not limited thereto and various changes and modifications may be made without departing from the spirit of the invention and the scope of the appended claims.