The parallax exists because the camera is set to the periphery of display in current videoconference. In this paper, we proposed a new system to eliminate this parallax by aligning user, transparent display and camera in the same axis. And we also adjusted the key parameters to take into account of camera and display.
Author KeywordsParallax-free; transparent display; videoconference;
Objective and backgroundDue to the traditional LCD use the opaque backlight module, the camera is set to the periphery of LCD. In this arrangement, the parallax issue between user and camera while in the videoconference always confuses the user. It is because the user used to look at the display rather than look at the camera, as shown in Fig.1
(a).On the other hand, the transparent LCD (T-LCD) becomes popular in LCD technology because it could show stylish and elegant images and bring a completely new visual experience to attract people's attention [1,2]. Therefore we combined T-LCD and camera to propose a new videoconference system by aligning user, T-LCD and camera in the same axis to eliminate the parallax issue, as shown in Fig.1 (b). there is no mutual gaze because the camera is in the edge of LCD (b) videoconference by using transparent display; there is mutual gaze because the camera is behind the transparent display
Experimental ResultsIn order to achieve the parallax-free videoconference system, a transparent light guide was used to replace traditional opaque backlight module. A transparent backlight module could also improve the blur issues by removing the optical films. We developed the transparent light guide with scattering function as the conventional diffuser and prism [3]. The side light type transparent light guide could provide an uniform R-G-B backlight for display as shown in Fig. 2. Besides, to improve the image quality of parallax-free videoconference system, a color filter-less LCD with fieldsequential-color (FSC) driving was used to increase display transmittance and reduce diffraction phenomenon.. The resulting transmittance of the color-filter-less T-LCD could be improved from 5% to 15%. The experiment scheme is shown in Fig.3. The camera was behind the transparent light guide to capture image, and the distance between color filter-less LCD and target was 300 mm.Timing sequence of the camera exposure and the RGB LEDs were set to 4.16ms, respectively, as shown in Fig. 4. According to the timing chart, display images of the T-LCD could be seen while the RGB LEDs were turned on and the camera could capture the image of target through the T-LCD only while the camera shutter was turned on.