COL 12(6), 060006(2014) CHINESE OPTICS LETTERS June 10, 2014
Large stereoscopic LED display by use of parallax barrier of
aperture grille type
(Invited Paper)
Hirotsugu Yamamoto
1,2∗
,HayatoNishimura
1
,TetsuyaAbe
1
, and Yoshio Hayasaki
2
1
Department of Optical Science and Technology, University of Tokushima,
2-1, Minamijosanjima, Tokushima City, Tokushima 7708506, Japan
2
Center for Optical Research and Education, Utsunomiya University,
7-1-2, Yoto, Utsunomiya City, Tochigi 3218585, Japan
∗
Corresponding author: hirotsugu yamamoto@cc.utsunomiya-u.ac.jp
Received March 11, 2014; accepted April 4, 2014; posted online Ma y 20, 2014
We propose a large parallax barrier by use of aperture grille. Main advantages of using aperture grille
include no reflection and no absorption in apertures, as well as wide viewing angle. These advantages are
investigated with theoretical calculations and experiments by use of several kinds of LED panels, such as
a fine-pitch LED panel and a 140-inch large LED panel. Limitations of viewing angle by parallax barrier
are analyzed in conventional black stripes on a transparent substrate type and in aperture grille type.
Experimental results show use of aperture grille increases contrast and reduce reflection on the aperture
surface.
OCIS codes: 120.2040, 330.1400.
doi: 10.3788/COL201412.060006.
1. Introduction
LED panels are used for digital signage. LED’s durabil-
ity
[1]
and high brightness are suitable for signage under
broad daylight. LED digital signage becomes pervasive
in public spaces such as stations, airports, exhibitions,
stadiums, and downtowns. On the viewpoint of advertis-
ers, it is important to attract more attentions of viewers
to their signage.
Three-dimensional (3D) display is one of the prospec-
tive display methods to attract more audiences. We have
been studying 3D display techniques for digital signage
by use of several kinds of full- color LED panels. Glass-
less 3D display methods are suitable for use in the public
spaces. Most of LED screens do not have as many pixels
as hig h-definition televisions now. Under this restriction
of pixels, we had set our first goal as a stereoscopic LED
display because two perspective views are the minimum
to provide depth perception based on binocular fusion.
Parallax barrier
[2,3]
is suitable for large-scale screens in
the public space because of its simple and scalable com-
position. Viewing zones of a stereoscopic LED display
by use of a parallax barrier have been analyzed
[4]
and
enlarged by the spaces between LED lamps
[5]
.Wehave
investigated designed interpupillary distances of par-
allax barrier
[6]
, a viewer’s movements to the designed
viewing zones
[7]
. We have also investigated variation
of parallax barrier patterns: by rotating the parallax
barrier, multiple images are provided according to the
viewing distance
[8]
. Furthermore, we have discovered a
new depth perception that was given by viewing LEDs
through ap ertures
[9]
.
Recently, new compositions of parallax barrier have
been proposed: rotating parallax barrier with LED arra-
ys provides omni-directional 3D display
[10]
; p olarization-
modulated parallax barrier enables frontal projection
[11]
;
active anaglyph parallax barrier maintains resolution of
each perspective image
[12]
. In this letter, we investigate
composition of parallax barrier for a large LED letter.
We compare the aperture grille type with the conven-
tional type of parallax barrier, which is comp osed of
black stripes painted on a transparent substrate. The
design of aperture g rille is described and is confirmed
by making aperture grilles for a 4-mm-pitch LED panel,
an 8-mm pitch LED panel, a 6-mm pitch LED panel in
140-inch size.
2. Design of parallax barrier for
a large LED panel
Principle and compositions of parallax barrier are
shown in Fig. 1. Stereoscopic images are column-sequen-
tially interleaved and displayed on an LED panel. Both
perspective images are separated by the opaque stripes,
called parallax barrier. The stereoscopic display by use of
Fig. 1. Compositions of parallax barrier. (a) Conv entional
type is black stripes painted on a transparent substrate. (b)
Aperture grille type is composed of opaque stripes.
1671-7694/2014/060006(5) 060006-1
c
2014 Chinese Optics Letters