Patent Publication Number: US-8120640-B2

Title: Videophone apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2006-302316, filed on Nov. 8, 2006, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a videophone apparatus, and more particularly a small-sized thin videophone apparatus mountable on a small-sized mobile terminal such as a mobile phone terminal. 
     2. Description of the Related Art 
       FIG. 1  shows a diagram illustrating an example of the conventional mobile phone terminal with a videophone function. A mobile phone terminal  100  includes a display  102  and a camera  104 , and a lens  106  is disposed in a different position from display  102 . Camera  104  images, for example, a user face through lens  106 , and the imaged image is transmitted to the terminal of the other communication party. At this time, since the face of the other communication party is displayed on display  102 , the user of mobile phone terminal  100  makes conversation while viewing display  102 . 
     Namely, when the user looks at the face of the other communication party displayed on display  102 , the visual line is directed to display  102 , and the user face imaged by camera  104  is displayed on the terminal of the other communication party in such a manner as the user is looking at a different place. As such, because the visual line of the user is directed to the direction of display  102 , not directed to the imaging direction, that is, lens  106  of camera  104 , the communication parties cannot meet eyes with each other through the display, which produces unnatural dialogue. 
     Further, when imaging the user himself or herself by use of a camera function of the mobile phone terminal, first, the user confirms his/her own expression, etc. displayed on display  102 , and then, it is necessary for the user to shift the visual line to the direction of camera lens  106  at the time of being imaged. As such, the videophone apparatus has been required to have a configuration to make the visual line at the time of viewing the display consistent with the visual line at the time of imaging. 
       FIG. 2  shows a diagram illustrating an exemplary to configuration of a lens &amp; half mirror portion in the conventional videophone apparatus enabling consistent visual lines. A half mirror  108  is disposed in front of display  102 , so that half mirror  108  can transmit light through the optical path on the display side of display  102 , and also reflects the optical path on the imaging side, so as to lead the light to the direction of lens  106  and camera  104 . Thus, it becomes possible to make the visual line for viewing display  102  consistent with the visual line directed to lens  106 . 
     Also, in the official gazette of the Japanese Unexamined Patent Publication No. 2004-135275 (hereafter referred to as Patent document 1), there is disclosed a device in which display on a display unit is reflected by a mirror, and a semi-transparent window to enable camera imaging is disposed on a portion of the mirror. By making conversation while viewing the display reflected by the mirror, the user can obtain consistent visual lines. 
     Further, in the official gazette of the Japanese Unexamined Patent Publication No. 2004-219742 (hereafter referred to as Patent document 2), there is disclosed a display device having a camera imaging window disposed on a screen for displaying a projected image. With the above configuration, consistent visual lines can be obtained when the user makes conversation while viewing the display projected on the screen. 
     However, according to the configuration shown in  FIG. 2 , although inconsistent visual lines can be eliminated, it is necessary to provide half mirror  108  corresponding to the overall display size of display  102 , and according to the size thereof, a sufficient depth is required for the device. This becomes an obstacle to small-sized thin videophone apparatus required when incorporating the videophone apparatus into a mobile phone terminal. 
     Further, in Patent document 1, because it is necessary to allow the display on the display unit to be reflected by the mirror, the shape of the videophone apparatus is restricted to have a structure so that the display may have a substantial angle from the mirror (for example, a mobile phone terminal of folding type). In addition, at the time of use, since the user looks into an image reflected by the mirror, the use feeling greatly differs as compared to the conventional mobile phone terminal. As a result, in contrast to a direct viewing type of the display, the handling convenience is largely degraded. 
     Also, in Patent document 2, as the display method, a projection method is applied, and other display methods than the projection method is not applicable. Accordingly, there is a problem that the method concerned is not applicable to liquid crystal display which is a mainstream today. In addition, because it is necessary to position a projection portion in front of the projection screen, the shape of the videophone apparatus is restricted (for example, a mobile phone terminal of folding type). 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a small-sized thin videophone apparatus in the videophone apparatus, enabling consistent visual lines during dialog with the other communication party. 
     Further, it is an object of the present invention to provide a small-sized thin videophone apparatus enabling consistent visual lines during dialog with the other communication party, in the videophone apparatus having a liquid crystal display or an organic EL display, irrespective of a display system. 
     As a first configuration of the videophone apparatus according to the present invention to achieve the aforementioned objects, in the videophone apparatus transmitting an image imaged by a camera and displaying the received image on a display, the videophone apparatus includes: a cover portion covering the surface of the display with a predetermined interval apart from the display; a half mirror being disposed inside the cover portion and on the surface of the display, and having an area smaller than the surface area of the display; a first lens of a convex lens being disposed between the display and the half mirror, and leading a portion of light corresponding to the display image to the half mirror; a second lens of a convex lens being disposed between the cover portion and the half mirror, and leading light transmitted through the half mirror to the cover portions and also leading light from outside the cover portion to the half mirror; and a third lens being disposed between the second lens and the half mirror, and leading light incident from the outside the cover portion and reflected by the half mirror, to the camera. 
     As a second configuration of the videophone apparatus according to the present invention, in the aforementioned first configuration, the videophone apparatus further includes a filter attenuating the luminance of the light reaching the cover portion, without being transmitted through the half mirror, among the light corresponding to the display image, to a luminance of the light being transmitted through the half mirror. 
     As a third configuration of the videophone apparatus according to the present invention, in the aforementioned first configuration, the videophone apparatus further includes an actuator for making the half mirror movable. 
     As a fourth configuration of the videophone apparatus according to the present invention, in the aforementioned first configuration, the videophone apparatus further includes: two sets of optical units each formed of the combination of the half mirror, the first lens, the second lens and the third lens, and the two sets of the optical units are disposed on the surface of the display inside the cover portion, mutually with a predetermined interval apart in the horizontal direction, and the third lenses of the optical units lead the light reflected by the halt mirrors of the optical units respectively to the left half area and the right half area of an imaging device provided on the camera. 
     Further scopes and features of the present invention will become more apparent by the following description of the embodiments with the accompanied drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a diagram illustrating an example of the conventional mobile phone terminal with a videophone function. 
         FIG. 2  shows a diagram illustrating an exemplary configuration of a lens &amp; half mirror portion of the conventional videophone apparatus enabling consistent visual lines. 
         FIG. 3  shows a diagram illustrating a first exemplary configuration of a lens &amp; half mirror portion of a videophone apparatus, according to an embodiment of the present invention. 
         FIG. 4  shows a diagram illustrating an optical path (optical path on the display side) from a liquid crystal display  110 . 
         FIG. 5  shows a diagram illustrating an optical path (optical path on the imaging side) to lead the light from a cover  112  to a camera  122 . 
         FIG. 6  shows a diagram illustrating a second exemplary configuration of a lens &amp;half mirror portion of a videophone apparatus, according to an embodiment of the present invention. 
         FIG. 7  shows a diagram illustrating a third exemplary configuration of a lens &amp; half mirror portion of a videophone apparatus, according to an embodiment of the present invention. 
         FIG. 8  shows a diagram illustrating a mobile phone terminal, which is a videophone apparatus, according to an embodiment of the present invention. 
         FIG. 9  shows a diagram illustrating a light reduction filter disposed on a display  110 . 
         FIG. 10  shows a diagram illustrating a configuration to enable a half mirror  120  to be movable. 
         FIG. 11  shows a diagram illustrating a configuration enabling stereo imaging. 
         FIG. 12  shows a diagram illustrating a configuration enabling stereo imaging. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The preferred embodiments of the present invention are described hereinafter referring to the charts and drawings. However, it is to be noted that the technical scope of the present invention is not limited to the embodiments described below. 
       FIG. 3  shows a diagram illustrating a first exemplary configuration of a lens &amp; halt mirror portion of a videophone apparatus, according to an embodiment of the present invention. The videophone apparatus according to the present invention is, for example, a mobile phone terminal having a built-in camera, and by means of the communication function of the mobile phone terminal, the communication of an image data imaged by the camera is carried out.  FIG. 3  is a cross-sectional view of a lens &amp; half-mirror portion of the mobile phone terminal, and the lens &amp; half mirror portion includes lenses  114 ,  116 ,  118  and a half mirror  120 . Between a display  110  of the mobile phone terminal and a cover (formed of, for example, a glass material)  112  being disposed with an interval between to display  110  so as to protect the above display (for example, of liquid crystal), lenses  114 ,  116 ,  118  and half mirror  120 , having a sufficiently small area as compared to the surface areas of display  110  and cover  112 , are disposed. 
     Half mirror  120  allows light from display  110  to transmit to the cover, and also allows light from cover  112  to reflect, so as to lead to camera  122 . Camera  122  is disposed in a position in which the reflected light from half mirror  120  can be imaged. 
       FIG. 4  shows a diagram illustrating an optical path (optical path on the display side) from liquid crystal display  110 , and  FIG. 5  shows a diagram illustrating an optical path (optical path on the imaging side) to lead the light from cover  112  to camera  122 . Lenses  114 ,  116  are disposed at opposite positions to sandwich half mirror  120 . As shown in  FIG. 4 , light from display  110  passes through lens  114 , and transmits through half mirror  120 , and further the light passes through lens  116  and is led to cover  112 . The light passing through lenses  114 ,  116  is displayed as an image having a magnification of one. Further, as shown in  FIG. 5 , the light from cover  112  passes through lens  116  and is reflected by half mirror  120 , and then the light passes through lens  118  and is led to camera  122 . 
     Because half mirror  120  has a sufficiently small area as compared to each surface area of display  110  and cover  112 , in order to efficiently collect the reflected light from half mirror  120 , it is necessary to dispose lens  118  as close as possible to half mirror  120 . Accordingly, as shown in  FIG. 4 , lens  118  becomes disposed on the surface of display  110 , and the shadow of lens  118  is undesirably displayed on cover  112  because of the light from display  110 . 
     To cope therewith, lens  118  is disposed between lenses  114 ,  116  which are convex lenses disposed on one and the other sides of half mirror  120 , respectively. By means of the refractive effects of lenses  114 ,  116 , the optical path is narrowed as shown in  FIG. 4 , and by disposing lens  118  between lens  114  and lens  116  on the optical path before being narrowed, it becomes possible to avoid the shadow of lens  118  from being imaged on the cover. 
     Further, lens  114  is a convex lens having a small diameter, with a viewing angle to obtain an imaging range of at least the range of a user face or greater, and in order to lead the image having the above viewing angle to camera  122  positioned apart, lenses  114 ,  118 , which are convex lenses, are combined. Lenses  114 ,  116 ,  118  are microlenses having sizes of the order of the size of the half mirror (of the order of a few millimeters) or smaller (a few millimeters or less). 
     Additionally, through the optical path passing through lens  114  and lens  116 , the image is reversed upside down. Therefore, by obtaining in advance the range of an image portion on display  110  corresponding to the optical path passing through lens  114  and lens  116 , the image in the above range is generated upside down beforehand at an image generation stage. With this, after passing through lens  114  and lens  116 , the image is displayed as a normal image. 
       FIG. 6  shows a diagram illustrating a second exemplary configuration of the lens &amp; half mirror portion of the videophone apparatus, according to the embodiment of the present invention. In the second exemplary configuration, it is configured to dispose a concave lens  115  between lens  114  and lens  116  (in the figure, between half mirror  120  and lens  114 ), so that an image of a portion passing through lens  114  and lens  116  is not reversed upside down. With this, in digital image processing at the image generation stage, it becomes unnecessary to reverse upside down beforehand to generate the image portion corresponding to the optical path passing through lens  114  and lens  116 . The digital image processing is realized through software processing by means of an image processing processor (for example, DSP) embedded in the videophone apparatus. 
       FIG. 7  shows a diagram illustrating a third exemplary configuration of the lens &amp; half mirror portion of the videophone apparatus, according to an embodiment of the present invention. In the third exemplary configuration, it is configured to set the mounting direction of camera  122  to the same as the display direction (i.e. the direction facing in front), and light being incident from lens  118  is reflected by a mirror  124 , and led to camera  122 . Since a camera embedded in the conventional mobile phone terminal has the same direction as the display direction, the conventional camera components can be used without modification, so that a manufacturing cost increase can be suppressed. 
       FIG. 8  shows a diagram illustrating a mobile phone terminal, which is a videophone apparatus according to an embodiment of the present invention. Inside cover  112  of display  110  of the mobile phone terminal, there is embedded the lens &amp; half mirror portion (namely, the combination of half mirror  120  with lenses  114 ,  116  and  118 ), which is characteristic in the present invention described in  FIGS. 3 through 7 . Accordingly, the visual line of the user being imaged becomes directed to the direction of display  110 , and thus, the user can make natural video conversation while meeting eyes with the other party. Preferably, the lens &amp; half mirror portion is mounted on a position in the vicinity of eye positions expected to be positioned when the face of the other party is displayed on display  110 . By this, consistent visual lines can be obtained. 
     Even when the user images himself or herself, the user can image an image having a visual line directed toward the camera and consistent with the imaging direction, while the user is looking at the user&#39;s own expression displayed on display  110 . 
       FIG. 9  shows a diagram illustrating a light reduction filter disposed on display  110 . In regard to the light from display  110 , the light passing through the lens &amp; half mirror portion has different luminance from the rest of light. The reason is that the luminance of the light passing through the lens &amp; half mirror portion is attenuated. 
     Accordingly, to make the luminance therebetween uniform, it may be possible to mount on display  110  a light reduction filter  130  for attenuating the luminance of the light not passing through the lens &amp; half mirror portion so as to adjust to the luminance of the light passing therethrough. For example, light reduction filter  130  is stuck on the internal face of cover  112 . 
     Further, in place of light reduction filter  130 , it may be possible to process to attenuate the light luminance not passing through the lens &amp; half mirror portion, through digital image processing by means of a built-in DSP. Oppositely, using the digital image processing, it may also be possible to relatively amplify the light luminance which passes through the lens &amp; half mirror portion. 
       FIG. 10  shows a diagram illustrating a configuration to allow half mirror  120  to be movable. As shown in the figure, one end of half mirror  120  is fixed, while on the other end, an actuator  132  constituted of a piezoelectric device is attached. Actuator  132  is fixed on a non-illustrated fixed end, and when actuator  132  is moved by a voltage applied on actuator  132 , the direction of half mirror  120  is shifted following the above movement. By making half mirror  120  movable, the imaging area range is varied, so as to enable adjustment to an optimal imaging area. 
     Actuator  132  to be attached is not limited to one, but, for example, a plurality of actuators may be attached so as to enable both panning (horizontal direction) and tilting (vertical direction) movements. 
       FIGS. 11 and 12  show diagrams explaining a configuration enabling stereo imaging. As shown in  FIG. 11 , inside cover  112 , two sets of lens &amp; half mirror portions are disposed apart at a predetermined interval in the horizontal direction. With the angle adjustment of both half mirrors  120 , a configuration is made to lead the optical paths on the imaging side to camera  122 . More specifically, as shown in  FIG. 12 , light from either one half mirror is made incident on the left (right) half area of an imaging plane of an imaging device (CCD, CMOS, etc.) mounted on camera  122 , while light from the other half mirror  120  is made incident on the other half area. 
     With this, a stereo image can be imaged using a single camera  122 , and by use of known processing and operation, the user can view as a three-dimensional image. 
     According to the present invention, when a user is viewing a display, the user face can be imaged from a position on the visual line directed to the display direction, and thus, the user can make natural videophone conversation while meeting eyes with the other party. 
     With the provision of a small-sized half mirror, which is sufficiently smaller than the surface area of the display and disposed inside the surface of the display, so as to perform imaging, small-sized thin videophone apparatus can be realized, which is applicable to a mobile phone terminal. 
     When a small-sized half mirror is used, it is necessary to dispose a lens for leading light reflected from the half mirror inside the surface of a display. With a structure of disposing a convex lens on the opposite side of the half mirror in the direction of the display indication, it becomes possible to prevent the shadow of the above lens from being displayed on the display surface. 
     Since any display type for use in a videophone apparatus may be applicable, such as liquid crystal display and organic EL display, and also, any camera type may be applicable (such as CCD and CMOS), the existing displays and cameras may be used intact. Accordingly, it is possible to suppress a cost increase. 
     The foregoing description of the embodiments is not intended to limit the invention to the particular details of the examples illustrated. Any suitable modification and equivalents may be resorted to the scope of the invention. All features and advantages of the invention which fall within the scope of the invention are covered by the appended claims.