Computer graphics processing and selective visual display system – Plural physical display element control system – Optical means interposed in viewing path
Reexamination Certificate
1997-01-23
2001-08-28
Saras, Steven J. (Department: 2775)
Computer graphics processing and selective visual display system
Plural physical display element control system
Optical means interposed in viewing path
C345S055000, C345S100000, C349S095000
Reexamination Certificate
active
06281861
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a spatial light modulator and to a directional display, such as an autostereoscopic three dimensional (3D) display.
DESCRIPTION OF THE RELATED ART
The term ‘spatial light modulator’ as used herein is defined to mean a device which produces as its output light whose intensity can be controlled. Thus, spatial light modulators include non-emitting devices such as liquid crystal devices (LCD) which modulate light supplied, for instance, from a backlight. However, spatial light modulators also include devices which emit light of controllable intensity, such as electroluminescent devices (ELD). Such spatial light modulators may be used in displays including two dimensional (2D) and 3D displays.
FIG. 1
of the accompanying drawings illustrates a known type of raster scan display such as in conventional television (TV) receivers having cathode ray tubes (CRT) as the display device. The video signal standard for conventional TV systems provides two fields which are interlaced to form a video frame. The display
1
is of the CRT type and
FIG. 1
illustrates the raster scan pattern or path on the screen which the electron beam of the CRT follows. A first field is illustrated by bold lines such as 2 and contains the odd lines of the image. A second field illustrated by lower density lines such as
3
contains the even lines of the image. As shown in
FIG. 1
, the even lines
3
are interlaced between the odd lines
2
so that the two fields of each frame do not use the same picture elements (pixels) or light emitting regions of the screen of the display
1
, i.e. only half of the pixels of the display are addressed in each field. This interlaced pattern was introduced in order to reduce display flicker at lower data (field) rates.
FIG. 2
illustrates progressive scanning as used in other known types of displays, such as VGA monitors. In this case, the lines
4
of each frame are scanned in order (progressively) and the same pixels or regions are scanned by corresponding lines of all frames.
FIG. 3
illustrates the layout of pixels and the colour filtering of an LCD spatial light modulator (SLM) of the type disclosed in EP 0752610. The pixels are arranged as rows and columns such that adjacent pairs of columns are contiguous in the direction of the rows. The colour filtering comprises horizontal stripes of repeating red, green and blue filters with each stripe covering a single row of pixels.
FIG. 4
of the accompanying drawings illustrates the use of the SLM
1
of
FIG. 3
in an autostereoscopic 3D display. The SLM is provided with a parallax device
5
illustrated diagrammatically as a lenticular screen comprising parallel lenticules, each of which cooperates with a plurality (three in
FIG. 4
) of pixel columns to generate viewing windows.
Colour data for each pixel of the image to be displayed are supplied in the form of red, green and blue colour signals RGB to triplets of the SLM pixels. Triplets of RCB pixels forming composite colour pixels are indicated by the apices of triangles such as 6 and 7. Arrangements of this type are disclosed in EP 0752610. Thus, the triangle
6
shown in
FIG. 3
illustrates the triplet of RGB pixels which constitute the first composite colour pixel of the first line (pixel (1,1)) of the image to be displayed whereas the triangle
7
in
FIG. 3
forming the first composite colour pixel of the second line (pixel (2,1)). The SLM
1
is thus used for progressive scanning without interlacing and this technique may be referred to as ‘one phase addressing’. This is indicated in
FIG. 4
by die large numeral ‘1’ appearing in the triangles
6
and
7
to indicate that each frame comprises a single field. With such an arrangement, the vertical resolution of the image is one third the vertical spatial resolution of the rows of pixels. Each pixel of the SLM
1
is addressed only once per frame.
This type of addressing to form composite colour pixels is particularly necessary for 3D autostereoscopic displays of the type illustrated diagrammatically in FIG.
4
. In such a display, several images (three in the display of
FIG. 4
) are spatially multiplexed by displaying vertical strips of the three 2D images in the groups of three columns of pixels associated with each parallax element of the parallax device
5
. In order to create an autostereoscopic full-colour image, the individual pixels of each composite colour pixel must be imaged into the same viewing zone by the parallax device
5
. Thus, the columns of pixels displaying the strips of each 2D image must be in the same horizontal position relative to the corresponding parallax elements. For example, as indicated by the triangle
6
in
FIG. 4
, the red and blue pixels are in the left hand column behind the parallax element
5
a
and the green pixel is in the left hand column behind the parallax element
5
b
so that all three pixels are imaged into the same viewing zone by the parallax device
5
.
Although it is theoretically possible to increase the vertical resolution of a display using an SLM
1
addressed as shown in
FIGS. 3 and 4
, there are practical difficulties. For instance, if the pixels of the SLM
1
are made to the current practical limits of spatial resolution, no further increase in resolution is possible. Also, increasing the vertical resolution by increasing the number of addressed rows can have a disadvantageous effect on display brightness or contrast. In the case of passive matrix displays, increasing the number of addressed rows directly reduces the display contrast.
SUMMARY OF THE INVENTION
According to a first aspect of the invention, there is provided a spatial light modulator for displaying M interlaced fields per frame where M is an integer greater than one, characterised by comprising a plurality of picture elements arranged in M different ways as sets of picture elements to form colour picture elements such that substantially all of the picture elements of the spatial light modulator are addressed in each of the M fields.
According to a second aspect of the invention, there is provided a spatial light modulator for displaying M interlaced fields of image data per frame where M is an integer greater than one, comprising a plurality of picture elements and a controller for controlling the supply of the image data to the picture elements such that, in each ith field where i is each integer satisfying 1≦i≦M, image data are supplied to a plurality of ith sets of picture elements such that each ith set constitutes a composite colour picture element, characterised in that the controller is arranged to control the supply of image data to the picture elements such that, for each jth field where j is each integer satisfying 1≦j≦M and i≠j, image data are supplied to a plurality of jth sets of picture elements such that each jth set constitutes a composite colour picture element, each ith set is different from each ith set and each ith set has at least one picture element belonging to a jth set.
It is thus possible to provide a spatial light modulator whose vertical resolution is effectively increased without increasing the number of picture elements. Most of the picture elements are used in each of the fields or addressing phases so that the perceived vertical resolution is greater than, for instance, the arrangement illustrated in
FIGS. 3 and 4
. In particular, it is possible to arrange addressing such that only (M−1) rows of picture elements are not used to display all of the M fields. The improved resolution may be achieved with little or no penalty in terms of manufacturing difficulty or cost.
Preferably each ith and jth set comprises three picture elements disposed at the apices of a triangle and each ith set has two picture elements belonging to a jth set. Such an arrangement permits conventional RGB picture elements to be used and maximises the number of picture elements used to display each of the interlaced fields in each addressing phase of the spatial light modulator.
The modulator may be embo
Lim John G.
Renner Otto Boisselle & Sklar
Saras Steven J.
Sharp Kabushiki Kaisha
LandOfFree
Spatial light modulator and directional display does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Spatial light modulator and directional display, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Spatial light modulator and directional display will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2503307