U.S. patent application number 09/828743 was filed with the patent office on 2001-09-20 for picture display method and apparatus.
This patent application is currently assigned to SONY CORPORATION. Invention is credited to Akimoto, Osamu, Hashimoto, Shunichi, Matsui, Takeshi, Tanaka, Yoshinori, Yoshida, Takuji.
Application Number | 20010022613 09/828743 |
Document ID | / |
Family ID | 13413222 |
Filed Date | 2001-09-20 |
United States Patent
Application |
20010022613 |
Kind Code |
A1 |
Matsui, Takeshi ; et
al. |
September 20, 2001 |
Picture display method and apparatus
Abstract
A picture display method and apparatus in which a light source
is lengthened in service life and optimum color reproduction is
realized, while the light utilization efficiency is improved to
reduce the power consumption and the size of the apparatus. The
red, green and blue illuminating light beams radiated from the
light-emitting diodes 12R, 12G and 12R, are illuminated via relay
lenses and field lenses on picture display light bulbs 11R, 11G and
11B and spatially modulated in intensity so as to be synthesized by
a synthesis prism 10 and so as to be projected to an enlarged scale
on a screen 17. The profile of the light radiating portions of the
light-emitting diodes 12R, 12G and 12B are set so as to be the same
or similar to the profile of a picture display area of each of the
picture display light bulbs 11R, 11G and 11B in order that the
profile of the light beam illuminated on the picture display area
will be in keeping with the profile of the picture display
area.
Inventors: |
Matsui, Takeshi; (Tokyo,
JP) ; Yoshida, Takuji; (Kanagawa, JP) ;
Hashimoto, Shunichi; (Kanagawa, JP) ; Tanaka,
Yoshinori; (Kanagawa, JP) ; Akimoto, Osamu;
(Tokyo, JP) |
Correspondence
Address: |
FROMMER LAWRENCE & HAUG LLP
745 FIFTH AVENUE
NEW YORK
NY
10151
US
|
Assignee: |
SONY CORPORATION
|
Family ID: |
13413222 |
Appl. No.: |
09/828743 |
Filed: |
April 9, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09828743 |
Apr 9, 2001 |
|
|
|
09046497 |
Mar 23, 1998 |
|
|
|
Current U.S.
Class: |
348/75 ;
348/E9.027 |
Current CPC
Class: |
H04N 9/3152 20130101;
H04N 9/3164 20130101; H04N 9/3182 20130101; H04N 9/3155
20130101 |
Class at
Publication: |
348/75 |
International
Class: |
A61B 001/04; H04N
007/18; H04N 009/47 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 24, 1997 |
JP |
9-069801 |
Jul 14, 1997 |
JP |
9-188596 |
Claims
What is claimed is:
1. A picture display apparatus comprising: spatial modulation means
for spatially modulating an illuminated light beam in accordance
with the information of a displayed picture for forming a picture;
a light source employing a light-emitting diode radiating the light
beam illuminated on said spatial modulation means; a projection
optical system for projecting the light beam modulated by said
spatial modulation means; and light beam shape setting means for
converting the cross-sectional profile of the light beam radiated
by said light source so as to be illuminated on said spatial
modulation means to a profile corresponding to the profile of a
picture forming area in said spatial modulation means.
2. The picture display apparatus as claimed in claim 1 wherein said
light beam shape setting means is realized by a light radiating
portion of said light source formed to a profile corresponding to
the profile of a picture forming area of said spatial modulation
means.
3. The picture display apparatus as claimed in claim 2 wherein the
profile of a light radiating portion of said light source is the
same as or similar to the picture forming area in said spatial
modulation means.
4. The picture display apparatus as claimed in claim 1 wherein said
light source has a plurality of light-emitting diodes having a
planarized array of light emitting portions; and wherein said light
beam shape setting means has driving means for selectively driving
a plurality of light-emitting diodes so that the cross-sectional
profile of the light beam radiated from the light source will be in
keeping with the profile of the picture forming area in said
spatial modulation means.
5. The picture display apparatus as claimed in claim 1 wherein said
light beam shape setting means has an optical element for varying
the cross-sectional profile of a light beam illuminated on said
spatial modulation means.
6. The picture display apparatus as claimed in claim 1 wherein said
light beam shape setting means varies the cross-sectional profile
of the light beam illuminated on said spatial modulation means in
association operatively with variations in the profile of the
picture forming area in said spatial modulation means.
7. The picture display apparatus as claimed in claim 1 further
comprising: brightness adjustment means for adjusting the
brightness of the light beam radiated from said light source.
8. A picture display apparatus comprising: spatial modulation means
for spatially modulating an illuminated light beam in accordance
with the information of a displayed picture for forming a picture;
a light source employing a light-emitting diode radiating the light
beam illuminated on said spatial modulation means; a projection
optical system for projecting the light beam modulated by said
spatial modulation means; and brightness adjustment means for
adjusting brightness of the light radiated by said light
source.
9. The picture display apparatus as claimed in claim 8 wherein said
light source has a plurality of light-emitting diodes for radiating
light beams of different wavelength ranges; and wherein said
brightness adjustment means can independently adjust the brightness
of the light radiated by the light-emitting diodes.
10. The picture display apparatus as claimed in claim 8 wherein
said light source includes a plurality of light-emitting diodes for
radiating light beams of different wavelength ranges for forming a
colored picture; said brightness adjustment means discriminating
the type of the displayed picture for automatically adjusting the
brightness of the light radiated by said light-emitting diodes in
meeting with the color temperature of a white picture corresponding
to the type of the discriminated picture.
11. A picture display apparatus for displaying a colored picture
having gradation in brightness by time-divisional display of a
plurality of monochromatic pictures, wherein said monochromatic
pictures having different display colors are sequentially displayed
so that monochromatic pictures of the same color are not displayed
consecutively.
12. The picture display apparatus as claimed in claim 11 wherein a
color picture is a plurality of time-divisionally represented
brightness pictures having different visually recognized brightness
values; and wherein each brightness picture is made up of three
unit pictures corresponding to three prime colors of the light.
13. A picture display method for displaying a colored picture
having gradation in brightness by time-divisional display of a
plurality of monochromatic pictures, wherein said monochromatic
pictures having different display colors are sequentially displayed
so that monochromatic pictures of the same color are not displayed
consecutively.
14. The picture display method as claimed in claim 13 wherein a
color picture is a plurality of time-divisionally represented
brightness pictures having different visually recognized brightness
values; and wherein each brightness picture is made up of three
unit pictures corresponding to three prime colors of the light.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a picture display method and
apparatus for displaying a picture by spatially modulating the
light outgoing from a light source and projecting the modulated
light.
[0003] 2. Description of the Related Art
[0004] Among picture display apparatus used for the purpose of
appreciating a picture, there is a projection type picture display
apparatus in which the light outgoing from a light source is
spatially modulated by a picture display light bulb for projection
on a screen. This projection type picture display apparatus is
classified into a front side projection type in which the picture
is projected from the front side, such as a screen, and a back side
projection type in which the picture is projected from the back
side of the screen. As this projection type picture display
apparatus, there is known such apparatus in which a white light
source, including a discharge type xenon lamp, a metal halide lamp
or a heat light emission type halogen lamp, is used as a light
source, and a liquid crystal light bulb is used as a picture
display light bulb.
[0005] FIG. 1 shows an illustrative structure of a conventional
projection type picture display device. This projection type
picture display device includes a lamp 201 emitting a white light
beam, a UV-IR cutting filter, not shown, for cutting the
ultraviolet light (UV light) and infrared light (IR light) of the
light radiated from the lamp 201, and a lens 202 for condensing the
light passed through the UV-IR cutting filter. This projection type
picture display device also includes a red color separating mirror
203 reflecting only the red wavelength component of the light
condensed by the lens 202 and transmitting other wavelength
components, and a green color separating mirror 204 for reflecting
only the green wavelength component passed through the red color
separating mirror 203 and transmitting other wavelength components.
The projection type picture display device also includes a blue
color separating mirror 205 for reflecting only the blue wavelength
component passed through the green color separating mirror 204 and
transmitting other wavelength components. As the lamp 201, a while
light source, such as a xenon lamp, a metal halide lamp or a
halogen lamp, is used. As the mirrors 203 to 205, dichroic mirrors
are used.
[0006] The projection type picture display device also includes a
cubic-shaped synthesis prism 210, arranged for causing the green
light reflected by the green color separating mirror 204 to fall on
a surface 210G of the synthesis prism 210, and a reflection mirror
206 for causing the red light reflected by the red color separating
mirror 203 to fall on a surface 210R of the synthesis prism
perpendicular to the surface 210G. The projection type picture
display device also includes a reflection mirror 207 for reflecting
the blue light reflected by the blue color separating mirror 205 so
as to fall on a surface 210B of the synthesis prism parallel to the
surface 210R of the synthesis prism 210.
[0007] The projection type picture display device also includes a
red picture display light bulb 211R arranged between the reflection
mirror 206 and the surface 210R of the synthesis prism 210, and a
green picture display light bulb 211G arranged between the green
color separating mirror 204 and the surface 210B of the synthesis
prism 210. The projection type picture display device also includes
a blue picture display light bulb 211B arranged between the
reflection mirror 207 and the surface 210B of the synthesis prism
210, and a projection lens 212 arranged facing a surface 210A
parallel to the surface 210G of the synthesis prism 210. The light
bulbs 211R, 211G and 211B may, for example, be rectangular in
shape. The light bulbs 211R, 211G and 211B are adapted for being
driven on the basis of red picture signals, green picture signals
and blue picture signals, respectively.
[0008] The projection type picture display device also includes a
red field lens 212R arranged between the reflection mirror 206 and
the red picture display light bulb 211R, and a green field lens
212G arranged between the green color separating mirror 204 and the
green picture display light bulb 211G. The projection type picture
display device also includes a blue field lens 212B arranged
between the reflection mirror 207 and the blue picture display
light bulb 211B, and an optical path length adjustment lens 213
arranged between the blue color separating mirror 204 and the blue
color reflection mirror 205. The projection type picture display
device also includes an optical path length adjustment lens 214
arranged between the blue color separating mirror 205 and the
reflection mirror 207.
[0009] The synthesis prism includes a reflecting mirror 210r for
reflecting only the red light incident from the surface 210R
towards the surface 210R, and a reflecting surface 210B for
reflecting only the blue light incident from the surface 210B
towards the surface 210A.
[0010] The above-mentioned components of the projection type
picture display apparatus are held by a suitable holder and
installed in this state in a casing 214.
[0011] In the projection type picture display apparatus, shown in
FIG. 1, the while light radiated from the lamp 201 is freed by the
UV-IR cutting filter of redundant wavelength light beams, that is
the UV and IR light beams, and condensed by the lens 202 so as to
fall on the red color separating mirror 203. Of the light incident
on the red color separating mirror 203, the red light is reflected
by the red color separating mirror 203. The reflected red light is
further reflected by the reflection mirror 206 to pass via red
field lens 212R through the red picture display light bulb 211R and
is spatially modulated based on red picture signals so as to fall
on the synthesis prism 210.
[0012] Of the light incident on the red color separating mirror
203, the light other than the red light is transmitted through the
red color separating mirror 203 to fall on the green color
separating mirror 204. Of the light incident on the green color
separating mirror 204, the green light is reflected by the green
color separating mirror 204 and transmitted via green field lens
212G through the green picture display light bulb 211G and is
spatially modulated based on red picture signals to fall on the
synthesis prism 210.
[0013] Of the light incident on the green color separating mirror
204, the light other than the green light is transmitted through
the green color separating mirror 204 to fall on the blue color
separating mirror 205. Of the light incident on the blue color
separating mirror 205, the blue light is reflected by the blue
color separating mirror 205, reflected by the reflection mirror 207
through the optical path length adjustment lens 214 and transmitted
via blue field lens 212B through the blue picture display light
bulb 211B and is spatially modulated based on blue picture signals
to fall on the synthesis prism 210.
[0014] The light beams of respective colors, modulated by the light
bulbs 211R, 211G and 211B, are synthesized by the synthesis prism
210 so as to be then radiated from the surface 210A to fall on the
projection prism 212. The light beams are then projected to an
enlarged scale on a transmission or reflection projection type
picture display apparatus type screen 213.
[0015] The above-described conventional projection type picture
display apparatus has a defect that, since the white light source
(lamp), such as xenon lamp, metal halide lamp or halogen lamp, used
as a light source, generally undergoes significant chronological
changes, and is of short service life, the picture tends to become
dark, while the lamp tends to be used up, such that the displayed
picture tends to become dark or the lamp has to be exchanged during
display of the picture.
[0016] On the other hand, the light beam radiated from the white
light source used in the conventional projection type picture
display apparatus is usually of a circular cross-section, whereas
the picture display light bulb is usually of an elongated shape.
Thus, in the conventional projection type picture display
apparatus, the diameter of the light beam radiated on the picture
display light bulb is set so as to be longer than the length of a
diagonal of the light bulb in order to illuminate the light from
the white light source uniformly on the picture display light bulb.
The result is that much light is wasted to lower the utilization
efficiency of light from the light source.
[0017] Moreover, the conventional projection type picture display
apparatus has a defect that, because of the low utilization
efficiency of light from the light source, a brighter light source
needs to be used for obtaining the necessary brightness, and a
defect that, since a larger light source needs to be used for
realizing the necessary brightness, it becomes necessary to reduce
the size of the projection type picture display apparatus.
[0018] In the projection type picture display apparatus, there are
occasions wherein a picture of a given aspect ratio is switched to
one of another aspect ratio, such as in the case of switching
between display of a picture with the aspect ratio of 3:4 of the
NTSC (National Television System Commission) and display of a
picture with the aspect ratio of 9:16 of the hi-vision system. In
this case, the shape and the area of an area actually used in the
picture display light bulb are changed depending on the aspect
ratio. With the conventional projection type picture display
apparatus, if the shape and the area of an area actually used in
the picture display light bulb are changed, the light volume
effectively used in the projection type picture display apparatus
is also changed, as a result of which the brightness of the
projected picture is also changed.
[0019] With the conventional projection type picture display
apparatus, the outgoing light beam of the white light source is
color-separated by color separation means, such as a dichroic
mirror, and the resulting separated light beams are illuminated on
picture display light bulbs associated with the respective color
signals. The result is that the wavelength distribution of the
separated colors depends on the wavelength distribution of the
outgoing light of the original white light source to make difficult
optimum color reproduction.
[0020] Moreover, in the white light source used in the conventional
projection type picture display apparatus, brightness modulation is
generally not possible or only narrow in brightness adjustment
range, with the response time of brightness modulation being
longer, such that, in the conventional projection type picture
display apparatus, the displayed picture cannot be adjusted in
brightness or can be adjusted only in a narrow range.
[0021] Also, if, in the conventional projection type picture
display apparatus, the radiated light of the white light source is
color-separated by, for example, a dichroic mirror so as to be
illuminated on picture display light bulbs associated with
respective color signals, it is difficult to adjust brightness of
the light from one color to another. Further, in the conventional
projection type picture display apparatus of the type in which
color filters are provided in the picture display light bulbs for
color separation, color adjustment can be done only by adjusting
the picture signals associated with respective colors or by
changing color filters used. Thus, with the conventional projection
type picture display apparatus, fine color adjustment is difficult
or can be realized only in a narrow range.
SUMMARY OF THE INVENTION
[0022] It is therefore an object of the present invention to
provide a picture display method and apparatus in which the light
source is durable and can reproduce colors optimally and in which
the light utilization efficiency can be improved to make possible
reduction of power consumption and reduction in size of the
apparatus.
[0023] It is another object of the present invention to provide a
picture display method and apparatus in which the light source is
durable and can reproduce colors optimally and in which brightness
or color can be adjusted easily.
[0024] In one aspect, the present invention provides a picture
display apparatus including spatial modulation means for spatially
modulating an illuminated light beam in accordance with the
information of a displayed picture for forming a picture, a light
source employing a light-emitting diode radiating the light beam
illuminated on the spatial modulation means, a projection optical
system for projecting the light beam modulated by the spatial
modulation means and light beam shape setting means for converting
the cross-sectional profile of the light beam radiated by the light
source to be illuminated on the spatial modulation means to a
profile corresponding to the profile of a picture forming area in
the spatial modulation means.
[0025] With the present picture display apparatus, the light beam
radiated from the light source comprised of light-emitting diodes
has its cross-sectional profile converted by light beam shape
setting means to a cross-sectional profile in meeting with the
profile of a picture forming area in spatial modulation means so as
to be illuminated on spatial modulation means. The spatial
modulation means spatially modulates the illuminated light in
keeping with the information of the displayed picture to from a
picture. The light modulated by spatial modulation means is
projected by a projection optical system on a screen or on an eye
of a viewer.
[0026] In another aspect, the present invention provides a picture
display apparatus including spatial modulation means for spatially
modulating an illuminated light beam in accordance with the
information of a displayed picture for forming a picture, a light
source employing a light-emitting diode radiating the light beam
illuminated on the spatial modulation means, a projection optical
system for projecting the light beam modulated by the spatial
modulation means and brightness adjustment means for adjusting
brightness of the light radiated by the light source.
[0027] With the present picture display apparatus, the light
radiated by the light source employing light-emitting diodes is
illuminated on and spatially modulated by spatial modulation means
in accordance with the information of the displayed picture to form
a picture. The light modulated by the spatial modulation means is
projected by a projection optical system on a screen or on the eye
of the viewer. The light radiated by the light source is adjusted
by brightness adjustment means.
[0028] In a further aspect, the present invention provides a
picture display apparatus for displaying a colored picture having
gradation in brightness by time-divisional display of a plurality
of monochromatic pictures, wherein the monochromatic pictures
having different display colors are sequentially displayed so that
monochromatic pictures of the same color are not displayed
consecutively.
[0029] In yet another aspect, the present invention provides a
picture display method for displaying a colored picture having
gradation in brightness by time-divisional display of a plurality
of monochromatic pictures, wherein the monochromatic pictures
having different display colors are sequentially displayed so that
monochromatic pictures of the same color are not displayed
consecutively.
[0030] In the picture display method and apparatus, monochromatic
pictures with different display colors are sequentially displayed.
These monochromatic pictures are contiguously displayed so that a
color picture is recognized due to the after-image effect proper to
the human viewing system. Since the monochromatic pictures of the
same color are configured so as not to be displayed consecutively,
color splitting or the edge chromatic phenomenon is not likely to
be produced even if a color picture is displayed by time-divisional
representation of plural monochromatic pictures, thus assuring
satisfactory color reproduction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIG. 1 is a schematic view showing an illustrative structure
of a conventional picture display apparatus.
[0032] FIG. 2 is a schematic view for illustrating the structure of
a picture display apparatus according to a first embodiment of the
present invention.
[0033] FIG. 3 is a block circuit diagram for illustrating the
structure of the picture display apparatus according to the first
embodiment of the present invention.
[0034] FIGS. 4A, 4B and 4C are schematic views for illustrating the
shape of an example of a picture display light bulb shown in FIG.
2.
[0035] FIGS. 5A, 5B and 5C are schematic views for illustrating the
shape of another example of a picture display light bulb shown in
FIG. 2.
[0036] FIGS. 6A, 6B are schematic views for illustrating the shape
of a light emitting diode shown in FIG. 2.
[0037] FIGS. 7A, 7B, 7C, 7D, 7E and 7F are schematic views showing
the results of an experiment conducted for scrutinizing into the
relation between the shape of the light radiating portion of the
light source and the shape of the illuminating light on the picture
display light bulb.
[0038] FIGS. 8A, 8B and 8C are schematic views showing an
illustrative arrangement of the light emitting diodes of the light
source device in the picture display device according to the second
embodiment of the present invention.
[0039] FIGS. 9A, 9b and 9C are schematic views showing another
illustrative arrangement of the light emitting diodes of the light
source device in the picture display device according to the second
embodiment of the present invention.
[0040] FIG. 10 is a schematic view for illustrating the structure
of a picture display apparatus according to a third embodiment of
the present invention.
[0041] FIG. 11 is a perspective view showing the structure of a
light beam shape conversion device in FIG. 10.
[0042] FIGS. 12A, 12B, 12C and 12D illustrate the relation between
the shape of the picture forming area of the picture display light
bulb in the third embodiment and the light beam shape.
[0043] FIG. 13 is a block circuit diagram for illustrating the
structure of a picture display apparatus according to a fourth
embodiment of the present invention.
[0044] FIG. 14 is a flow diagram for illustrating the operation of
the picture display apparatus according to the fourth embodiment of
the present invention.
[0045] FIG. 15 is a schematic view for illustrating the structure
of a picture display apparatus according to a fifth embodiment of
the present invention.
[0046] FIG. 16 is a block circuit diagram for illustrating the
structure of the picture display apparatus according to the fifth
embodiment of the present invention.
[0047] FIGS. 17A, 17B, 17C, 17D illustrate the operation of the
picture display apparatus according to the fifth embodiment of the
present invention.
[0048] FIGS. 18A, 18B, 18C, 18D, 18E illustrate the principle of
the digital gradation display system used in the picture display
apparatus according to a sixth embodiment of the present
invention.
[0049] FIGS. 19A, 19B, 19C, 19D illustrate the operation of the
picture display apparatus according to the sixth embodiment of the
present invention.
[0050] FIG. 20 is a schematic view for illustrating the structure
of a picture display apparatus according to a seventh embodiment of
the present invention.
[0051] FIG. 21 is a schematic view for illustrating the structure
of a picture display apparatus according to an eighth embodiment of
the present invention.
[0052] FIG. 22 is a schematic view for illustrating the structure
of a picture display apparatus according to a ninth embodiment of
the present invention.
[0053] FIG. 23 is a schematic view for illustrating the structure
of a picture display apparatus according to a tenth embodiment of
the present invention.
[0054] FIG. 24 illustrates an edge chromatic phenomenon.
[0055] FIG. 25 is a diagrammatic view for illustrating how the
occurrence of the edge chromatic phenomenon can be suppressed by
shortening the time of continuous display of a monochromatic
picture.
[0056] FIGS. 26A, 26B, 26C and 26D illustrate a typical operation
of the picture display apparatus according to the present
invention.
[0057] FIGS. 27A, 27B, 27C and 27D illustrate another typical
operation of the picture display apparatus according to the present
invention.
[0058] FIGS. 28A, 28B, 28C and 28D illustrate still another typical
operation of the picture display apparatus according to the present
invention.
[0059] FIGS. 29A, 29B, 29C and 29D illustrate a further typical
operation of the picture display apparatus according to the present
invention.
[0060] FIGS. 30A, 30B, 30C and 30D illustrate a further typical
operation of the picture display apparatus according to the present
invention.
[0061] FIGS. 31A, 31B, 31C and 31D illustrate a further typical
operation of the picture display apparatus according to the present
invention.
[0062] FIGS. 32A, 32B, 32C and 33D illustrate a further typical
operation of the picture display apparatus according to the present
invention.
[0063] FIGS. 33A, 33B, 33C and 33D illustrate yet another typical
operation of the picture display apparatus according to the present
invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0064] Referring to the drawings, preferred embodiments of the
present invention will be explained in detail.
[0065] FIG. 2 is a schematic view for illustrating the structure of
a projection type picture display device according to a first
embodiment of the present invention. This picture display device
includes a cubic-shaped synthesis prism 10, a green picture display
light bulb 11G arranged for facing a surface 10G of the synthesis
prism 10, a red picture display light bulb 11R arranged for facing
a surface 10R extending perpendicular to the surface 10G of the
synthesis prism 10, and a blue picture display light bulb 11B
arranged for facing a surface 10B extending parallel to the surface
10R of the synthesis prism 10. The picture display light bulbs 11R,
11G and 11B correspond to spatial modulation means in the present
invention.
[0066] The picture display device further includes red
light-emitting diode 12R, a green light-emitting diode 12G and a
blue light-emitting diode 12b, arranged laterally of the picture
display light bulbs 11R, 11G and 11B for operating as light sources
for illuminating red, green and blue illuminating light beams to
the picture display light bulbs 11R, 11G and 11B, respectively. The
red, green and blue illuminating light beams herein mean light
beams with certain wavelength distribution, instead of the sole
wavelength light beam.
[0067] There are sequentially arrayed, between the red
light-emitting diode 12R and the red picture display light bulb
11R, a red relay lens 13R and a red field lens 14R, beginning from
the side of the red light-emitting diode 12R. There are similarly
arrayed, between the green light-emitting diode 12G and the green
picture display light bulb 11G a green relay lens 13G and a green
field lens 14G, beginning from the side of the green light-emitting
diode 12G. There are also arrayed, between the blue light-emitting
diode 12B and the blue picture display light bulb 12B, a blue relay
lens 13B and a blue field lens 14B, beginning from the side of the
blue light-emitting diode 12B.
[0068] The picture display device also includes a projection lens
15 formed by picture display light bulbs 11R, 11G and 11B for
facing a surface 10A of the synthesis prism 10 parallel to its
surface 10G and which is adapted for projecting the light of an
image synthesized by the synthesis prism 10 on a transmission type
or reflection type screen 17 in case of a back surface projection
type picture display device or a front surface projection type
picture display device, respectively. The above-mentioned various
constituent elements are held by a suitable holder and mounted in
this state in a casing 16.
[0069] The synthesis prism 10 is comprised of a dichroic prism
having a reflective surface 10r for reflecting only a red light
beam incident from the surface 10R towards the surface 10A and a
reflective surface 10B for reflecting only a blue light beam
incident from the surface 10B towards the surface 10A.
[0070] The picture display light bulbs 11R, 11G and 11B are
transmission type liquid crystal light bulbs each having a large
number of pixels capable of controlling light transmissivity. These
picture display light bulbs 11R, 11G and 11B use liquid crystals,
such as twisted nematic (TN), super twisted nematic (STN) or FLC
(ferroelectric liquid crystal). These picture display light bulbs
11R, 11G and 11B may be driven in accordance with the active matrix
system or with the simple matrix system. If the active matrix
system is used, a thin film transistor (TFT) or a metal insulator
metal (MIM) is used as a switching device.
[0071] A red light-emitting diode employing an AlGaAs or AlGaInP
based compound semiconductor is used as the red light-emitting
diode 12R, while a blue light-emitting diode and a blue
light-emitting diode employing a Gain based or a ZnSe based
compound semiconductor are used as the green light-emitting diode
12G and the bleu light-emitting diode 12B, respectively.
[0072] The relay lenses 13R, 13G and 13B are lenses for forming
two-dimensional images of light radiating portions of the
light-emitting diodes 12R, 12G and 12b on the picture display light
bulbs 11R, 11G and 11B, respectively. The field lenses 14R, 14G and
14B are lenses for forming images of the back focal plane of the
relay lenses 13R to 13B at the position of the incident pupil of
the projection lens 15.
[0073] FIG. 4 shows an illustrative shape of the picture display
light bulb 11 (being a generic appellation for 11R to 11B). The
picture display light bulb 11 in the present embodiment has an
aspect ratio of 3:4, as shown in FIG. 4A. Although the picture
display light bulb 11 has a diagonal length of 1.3 inches
(approximately 33 mm), it may be of a smaller or a larger size.
With the picture display light bulb 11, shown in FIG. 4, the entire
area of the light bulb may be a picture forming area 21 to form a
picture having an aspect ratio 3:4 as in the NTSC system, as shown
in FIG. 4B, or an area of the light bulb excluding part of upper
and lower edges thereof may be a picture forming area 22 to form a
picture having an aspect ratio 9:16 as in the hi-vision system, as
shown in FIG. 4C.
[0074] FIG. 5 shows another illustrative shape of the picture
display light bulb 11. The picture display light bulb 11 in the
present embodiment has an aspect ratio of 9:16, as shown in FIG.
5A. With the picture display light bulb 11, shown in FIG. 4, the
entire area of the light bulb may be a picture forming area 23 to
form a picture having an aspect ratio 9:16, as shown in FIG. 5B, or
an area of the light bulb excluding part of left and right edges
thereof may be a picture forming area 24 to form a picture having
an aspect ratio 3:4, as shown in FIG. 5C.
[0075] FIG. 6 illustrates a typical shape of the light-emitting
diode 12 (being a generic appellation of 12R, 12G and 12B). In the
present embodiment, the light beam illuminated on the picture
forming area in the picture display light bulb 11 is selected to
correspond in shape to the picture forming area in the picture
display light bulb 11 so that the cross-sectional shape of the
light beam illuminated on the picture forming area in the picture
display light bulb 11 will correspond to the shape of the picture
display light bulb 11.
[0076] The light radiating portion of the light radiating portion
25 of the light-emitting diode 12 shown in FIG. 6A is shaped to
correspond to the aspect ratio of 3:4. The light-emitting diode 21
of the present embodiment is used when the shape of the light
radiating portion 25 is the same as or similar to the picture
forming area 24 shown in FIG. 5C and when it is desired to form a
picture with the aspect ratio of 3:4 by the picture display light
bulb 11 as shown in FIGS. 4B or 5C.
[0077] The light radiating portion of the light radiating portion
25 of the light-emitting diode 12 shown in FIG. 6B is shaped to
correspond to the aspect ratio of 3:4. The light-emitting diode 12
of the present embodiment is used when the shape of the light
radiating portion 25 is the same as or similar to the picture
forming area 24 shown in FIG. 5B and when it is desired to form a
picture with the aspect ratio of 9:16 by the picture display light
bulb 11 as shown in FIGS. 4C or 5B.
[0078] The shape of the picture display light bulb 11 may be of any
suitable shape without being limited to the aspect ratio of 3:4 or
9:16 as shown in FIGS. 4 and 5. The shape of the picture forming
area in the picture display light bulb 11 may also be of any
suitable shape without being limited to the aspect ratio of 3:4 or
9:16. In any case, the shape of the light radiating portion of the
light-emitting diode 12 is set so that the cross-sectional shape of
the light beam illuminated on the picture forming area in the
picture display light bulb 11 will correspond to the shape of the
picture forming area.
[0079] Meanwhile, the shape of the light radiating portion is not
necessarily the same as or similar to the shape of the picture
forming area. This will be explained with reference to FIG. 7
showing the results of experimentation as to the relation between
the shape of the light radiating portion of the light source and
the shape of the illuminating light in the picture display light
bulb 11.
[0080] Specifically, FIG. 7A shows the light emitting state of a
light source when the light radiating portion has the shape of a
rectangle having an aspect ratio of 3:4, while FIG. 7B shows the
illuminated state on the picture display light bulb 11 in such
case. Similarly, FIG. 7C shows the light emitting state of a light
source when the light radiating portion has the shape of a
rectangle having an aspect ratio of 9:16, while FIG. 7D shows the
illuminated state on the picture display light bulb 11 in such
case. On the other hand, FIG. 7E shows the light emitting portion
and the illuminating state of the light source in case the light
radiating portion of the light source is preferably shaped so as to
be swollen outwards at the corners of the rectangle. FIG. 7F shows
the illuminated state of the picture display light bulb 11 in this
case. In FIGS. 7A, 7C and 7E, A1 denotes an area of uniform
brightness. In FIGS. 7B, 7D and 7F, B1 to B5 denotes an area with
brightness in terms of a relative value of not less than 0.9 and
not larger than 1, an area with brightness in terms of a relative
value of not less than 0.8 and less than 0.9, an area with
brightness in terms of a relative value of not less than 0.7 and
less than 0.8, an area with brightness in terms of a relative value
of not less than 0.3 and less than 0.7, an area with brightness in
terms of a relative value of not less than 0.1 and less than 0.3,
respectively.
[0081] It is seen from FIGS. 7A to 7D that, if the light radiating
portion of the light source is rectangular in shape, the
illuminated light on the picture display light bulb 11 is also
rectangular with rounded corners. Thus, if the picture forming area
in the picture display light bulb 11 is rectangular, the state of
the light radiating portion of the light source is preferably
shaped so as to be swollen outwards at the corners of the rectangle
as shown in FIG. 7E since then the shape of illuminating light is
closer to a rectangular shape. That is, the shape of the light
radiating portion of the light source is desirably set in an
appropriate manner so that the cross-sectional shape of the light
beam illuminated on the picture forming area on the picture display
light bulb II will correspond to the shape of the picture forming
area.
[0082] FIG. 3 is a block diagram showing the circuit structure of a
picture display device of the present embodiment. Referring to FIG.
3, the present embodiment of the picture display device includes a
picture signal processing circuit 31 to which is entered a picture
signal VS and which generates a red picture signal, a green picture
signal and a blue picture signal corresponding to the red picture,
a green picture and a blue picture, respectively. The picture
display device also includes a red picture memory 32R, a green
picture memory 32G and a blue picture memory 32B for transiently
storing the red picture signal, green picture signal and the blue
picture generated by the picture signal processing circuit 31. The
picture display device also includes a red light bulb driving
circuit 33R connected to the picture signal processing circuit 31
and to the red picture memory 32R for driving a red picture
displaying light bulb 11R, a green light bulb driving circuit 33G
connected to the picture signal processing circuit 31 and to the
green picture memory 32G for driving a green picture displaying
light bulb 11G and a blue light bulb driving circuit 33B connected
to the picture signal processing circuit 31 and to the blue picture
memory 32B for driving a blue picture displaying light bulb
11B.
[0083] The picture display device also includes a red
light-emitting diode driving circuit 34R for driving the red
light-emitting diode 12R, a green light-emitting diode driving
circuit 34G for driving the green light-emitting diode 12G and a
blue light-emitting diode driving circuit 34B for driving the blue
light-emitting diode 12B. In the drawing, the light-emitting diode
is denoted as LED. The picture display device further includes a
controller 35 for controlling the picture signal processing circuit
31 and the light-emitting diode driving circuits 34R, 34G and 34B.
The controller 35 may, for example, be comprised of a
micro-computer.
[0084] The light-emitting diode driving circuits 34R, 34G and 34B
include means for switching the variable resistor or resistor for
varying the voltage applied across the light-emitting diodes 12R,
12G and 12B for independently adjusting the brightness of the light
radiated from the light-emitting diodes 12R to 12B.
[0085] The operation of the picture display device of the present
embodiment is hereinafter explained.
[0086] Referring to FIG. 3, the picture signal VS is entered to the
picture signal processing circuit 31 which then generates a red
picture signal, a green picture signal and a blue picture signal to
be stored in the red picture memory 32R, green picture memory 32G
and in the blue picture memory 32B, respectively. The light bulb
driving circuits 33R, 33G and 33B read out the respective color
picture signals at a pre-set period from the picture memories 32R,
32G and 32B to drive the picture display light bulbs 11R, 11G and
11B, based on the read-out picture signals, respectively.
[0087] The light-emitting diode driving circuits 34R, 34G and 34B
drive the light-emitting diodes 12R, 12G and 12B for perpetually or
suitably lighting the light-emitting diodes 12R, 12G and 12B,
respectively.
[0088] Referring to FIG. 2, the uniform red illuminating light
radiated from the red light-emitting diode 12R is illuminated via
relay lens 13R and field lens 14R on a red picture display light
bulb 11R so as to be thereby spatially modulated in intensity to
fall on the synthesis prism 10. Similarly, the uniform green
illuminating light radiated from the green light-emitting diode 12G
is illuminated via relay lens 13G and field lens 14G on a green
picture display light bulb 11G so as to be thereby spatially
modulated in intensity to fall on the synthesis prism 10, while the
uniform blue illuminating light radiated from the blue
light-emitting diode 12B is illuminated via relay lens 13B and
field lens 14B on a blue picture display light bulb 11B so as to be
thereby spatially modulated in intensity to fall on the synthesis
prism 10.
[0089] The light beams of the respective colors, modulated by the
picture display light bulbs 11R, 11G and 11B, are synthesized by
the synthesis prism 10 so as to be radiated from the surface 10A to
be projected on the screen 17 by the projection lens 15 to an
enlarged scale to display a color picture on the screen 17.
[0090] With the present embodiment of the picture display device,
as described above, the light source is improved in durability by
employing the light-emitting diode 12 as the light source, thus
saving the labor of exchanging the light sources. Also, since the
wavelengths of the radiated light beams of the light-emitting
diodes 12R, 12G and 12B are of a narrow range, the wavelength
distribution of the various colors is not dependent on the
wavelength distribution of the radiated light beam of the while
light source, as occurs when color-separating the radiated light
beam of the white light source. Thus, the range of the colors that
can be represented by the synthesis of the outgoing light beams of
the light-emitting diodes 12R, 12G and 12B is broader thus enabling
optimum color reproduction. Moreover, since the light-emitting
diode consumes less power and is of a smaller size than the white
light source, the power consumption can be reduced as compared to
the case of using the white light source as the light source thus
enabling reduction in size of the picture display device.
[0091] In addition, in the present embodiment of the picture
display device, since the light radiating portion of the
light-emitting diode 12 has a shape corresponding to the shape of
the picture forming area of the picture display light bulb 11,
specifically, the same shape or the similar shape, and hence the
cross-sectional shape of the light beam illuminated on the picture
forming area corresponds to the shape of the picture forming area,
the light utilization efficiency is improved as compared to the
case of using the white light source which gives a circular
cross-section of the light beam, thus further saving the power
consumption and reducing the size of the device.
[0092] With the picture display device of the present embodiment,
the light radiated by the light-emitting diodes 12R, 12G and 12B
can be adjusted independently this broadening the color adjustment
range as compared to the conventional system. If the light-emitting
diodes 12R, 12G and 12B differ in efficiency from color to color,
the applied voltage or the injected current to the light-emitting
diodes 12R, 12G and 12B can be previously varied by the
light-emitting diode driving circuits 34R, 34G and 34B for
independently adjusting the brightness of the light radiated by the
light-emitting diodes 12R, 12G and 12B in order to set the color
temperatures f the white picture screen to, for example, 9300 or
6500.degree.. It is also possible for the viewer to adjust the
brightness of the light beam radiated by the light-emitting diodes
12R, 12G and 12b to make color adjustment to suit to his or her
liking.
[0093] Referring to FIGS. 8 and 9, the picture display device
according to the second embodiment of the present invention is
explained.
[0094] In the present embodiment of the picture display device,
plural light source devices 42, each comprised of plural
light-emitting diodes having respective planar light radiating
portions, are provided in place of the sole light-emitting diode 12
according to the previous embodiment. These light-emitting diodes
are selectively driven so that the cross-sectional shape of the
light beam radiated from the light source device 42 will correspond
to the shape of the picture forming area of the picture display
light bulb 11. The light source device 42 used in place of the
light-emitting diode 12R is made up of plural red light-emitting
diodes, while the light source device 42 used in place of the
light-emitting diode 12G is made up of plural green light-emitting
diodes 12G and the light source device 42 used in place of the
light-emitting diode 12B is made up of plural blue light-emitting
diodes 12B. In the present embodiment, the light-emitting diode
driving circuits 34R, 34G and 34B of various colors in FIG. 2 can
selectively drive plural light-emitting diodes provided in the
associated color light source devices 42.
[0095] FIG. 8A shows an illustrative arrangement of plural
light-emitting diodes in the light source device 42. In the light
source device 42 of the instant embodiment, light-emitting diodes
41 having circular-shaped planar light-emitting portions are
arrayed in 12 (vertical direction).times.16 (horizontal direction)
matrix configuration. With the present light source device 42, all
light-emitting diodes 41 can be driven, as shown in FIG. 8B, so
that the light radiating portion of the light source device 42 will
be rectangular with the aspect ratio of 3:4. In addition, 9 column
of the light-emitting diodes 41, excluding upper and lower three
columns of the entire light-emitting diodes 41, may be selectively
driven so that the light radiating portion of the light source
device 42 will be rectangular with the aspect ratio of 9:16. The
light-emitting state shown in FIG. 8B is used when forming a
picture having the aspect ratio of 3:4 by the picture display light
bulb 11, while the light-emitting state shown in FIG. 8C is used
when forming a picture having the aspect ratio of 9:16 by the
picture display light bulb 11.
[0096] FIG. 9A shows an illustrative arrangement of plural
light-emitting diodes in the light source device 42. In the light
source device 42 of the instant embodiment, light-emitting diodes
41 having circular-shaped planar light-emitting portions are
arrayed in a 9 (vertical direction).times.16 (horizontal direction)
matrix configuration. With the present light source device 42, all
light-emitting diodes 41 can be driven, as shown in FIG. 9C, so
that the light radiating portion of the light source device 42 will
be rectangular with the aspect ratio of 9:16. In addition, 12
column of the light-emitting diodes 41, excluding upper and lower
four columns of the entire light-emitting diodes 41, may be
selectively driven so that the light radiating portion of the light
source device 42 will be rectangular with the aspect ratio of 3:4.
The light-emitting state shown in FIG. 9B is used when forming a
picture having the aspect ratio of 3:4 by the picture display light
bulb 11, while the light-emitting state shown in FIG. 9C is used
when forming a picture having the aspect ratio of 9:16 by the
picture display light bulb 11.
[0097] The arrangement of the plural light-emitting diodes 41 in
the light source device 42 may be set optionally without being
limited to the examples shown in FIGS. 8A or 9A. The shape of the
light radiating portion in the light source device 42 formed by
selectively driving plural light-emitting diodes may also be
optionally set to suit to the shape of the picture forming area in
the picture display light bulb 11 without being limited to the
examples shown in FIGS. 8B, 8C or 9B, 9C.
[0098] With the picture display device of the present embodiment,
the shape of the light radiating portion in the light source device
42 can be optionally set by selectively driving the plural
light-emitting diodes 41 provided in the light source device 42.
This makes it possible to have the light source device 42 cope with
various shapes of the picture forming areas in the picture display
light bulb 11. The structure and the operation of the present
embodiment are otherwise the same as those of the first
embodiment.
[0099] Referring to FIGS. 10 to 12, a picture display device of a
third embodiment of the present invention is explained.
[0100] FIG. 10 schematically shows the structure of a picture
display device of the third embodiment. This picture display device
includes a red light-emitting diode 44R, a green light-emitting
diode 44G and a blue light-emitting diode 44B each having a
circular planar shape of the light radiating portion. The picture
display device of the present embodiment also includes light beam
shape changing devices 50R, 50G and 50B between the field lens 14R
and the picture display light bulb 11R, between the field lens 14G
and the picture display light bulb 11G and between the field lens
14B and the picture display light bulb 11B, respectively.
[0101] FIG. 11 is a perspective view showing the structure of the
light beam shape changing device 50 (generic appellation of 50R,
50G and 50B). This light beam shape changing device 50 includes two
cylindrical lenses 51, 52. The radius of curvature of the curved
surface of the cylindrical lens 52 is selected to be larger than
that of the cylindrical lens 51. One ends of the cylindrical lenses
51, 52 are connected to one ends of levers 53, 54, while the
opposite ends of the levers 53, 54 are connected to a common rotary
shaft 55. A rotary shaft 55 is rotatably supported by a bearing 56
unit secured to a casing 16. To the rotary shaft 55 is connected a
manual lever 57. The cylindrical lenses 51, 52 correspond to the
optical devices of the present invention and are used to vary the
cross-sectional shape of the light beam illuminated on the picture
display light bulb 11.
[0102] It is also possible to provide a common lever for
interlocking the manual levers 57 for the light beam shape changing
devices 50R, 50G and 50B so that the common lever will be protruded
outwardly of the casing 16, such that, by actuating this common
lever, the manual levers 57 of the totality of the light beam shape
changing devices 50R, 50G and 50B will be actuated
simultaneously.
[0103] The light beam shape changing device 50 is designed so that,
by rotating the manual levers 57, the levers 53, 54 will be rotated
about the rotary shaft 55 as the center of rotation so that one of
the cylindrical lenses 51, 52 will be selectively inserted into the
illuminating light paths reaching the picture display light bulb 11
from the light-emitting diode 12. If the cylindrical lens 51 is
inserted into the illuminating light path, the cross-sectional
shape of the light beam illuminated on the picture display light
bulb 11 is a transversely elongated elliptical shape. The
cross-sectional shape of the light beam is set in the present
embodiment so that, when the light beam is illuminated on the
picture forming area having the aspect ratio of 9:16, the picture
forming area in tis entirety can be covered, while an area
trespassing the picture forming area will be as small as possible.
On the other hand, if the cylindrical lens 52 is inserted into the
illuminating light path, the cross-sectional shape of the light
beam illuminated on the picture display light bulb 11 is a
transversely elongated elliptical shape closer to a circular shape.
The cross-sectional shape of the light beam is set in the present
embodiment so that, when the light beam is illuminated on the
picture forming area having the aspect ratio of 3:4, the picture
forming area in its entirety can be covered, while an area
trespassing the picture forming area will be as small as
possible.
[0104] Thus, in the picture display device of the present
embodiment, if, in the picture display device of the present
embodiment, a picture with an aspect ratio of 3:4 as shown in FIG.
12A is to be formed, with the use of the picture display light bulb
11 having the aspect ratio of 9:16, the cylindrical lens 52 is
inserted into the illuminating light path to illuminate the light
beam 57 of the transversely elongated elliptical shape closer to a
circular shape on the picture forming area 24 of the picture
display light bulb 11. If a picture with an aspect ratio of 9:16 as
shown in FIG. 12B is to be formed, the cylindrical lens 51 is
inserted into the illuminating light path to illuminate the light
beam 58 of the transversely elongated elliptical shape on the
picture forming area 23 of the picture display light bulb 11. If,
with the use of the picture display light bulb 11 having the aspect
ratio of 3:4, a picture with an aspect ratio of 3:4 as shown in
FIG. 12C is to be formed, the cylindrical lens 52 is inserted into
the illuminating light path to illuminate the light beam 57 of the
transversely elongated elliptical shape closer to a circular shape
on the picture forming area 21 of the picture display light bulb
11. If picture with an aspect ratio of 9:16 as shown in FIG. 12D is
to be formed, the cylindrical lens 51 is inserted into the
illuminating light path to illuminate the light beam 58 of the
transversely elongated elliptical shape on the picture forming area
22 of the picture display light bulb 11.
[0105] Since the cross-sectional shape of the light beam
illuminated on the picture display light bulb 11 can be changed by
the light beam shape changing device 50, it becomes possible for
the light source to cope with the plural shapes of the picture
forming areas of the picture display light bulb 11 without
exchanging the light source. The structure and the operation of the
present embodiment are otherwise the same as those of the first
embodiment.
[0106] Referring to FIGS. 13 and 14, a picture display device
according to a fourth embodiment of the present invention is
explained.
[0107] With the present embodiment of the picture display device,
switching between the cylindrical lenses 51, 52 in the light beam
shape changing device is performed automatically in association
with changes in the shape of the picture forming area in the
picture display light bulb 11, while the type of the displayed
picture is discriminated and the light radiated by the
light-emitting diodes of the respective colors is automatically
adjusted in brightness in keeping with the color temperature of the
white picture associated with the discriminated picture type.
[0108] Referring to the block diagram of FIG. 13, the picture
display device of the present embodiment includes light beam shape
changing devices 60R, 60G and 60B, in place of the light beam shape
changing devices 50R, 50G and 50B of the third embodiment. These
light beam shape changing devices 60R, 60G and 60B correspond to
the light beam shape changing devices 50R, 50G and 50B except that
the manual levers 57 are omitted and a motor 61 for rotating the
rotary shaft 55 is provided in the bearing unit 56.
[0109] The picture display device of the present embodiment also
includes a motor driving circuit 62 for driving the motor 61 for
the light beam shape changing devices 60R, 60G and 60B. This motor
driving circuit 62 is adapted to be controlled by a controller 35.
Also, the light-emitting diode driving circuits 34R, 34G and 34B in
the present embodiment are adapted for adjusting the brightness of
the light radiated from the associated light-emitting diodes 12R,
12G and 12b under control by the controller 35. The controller 35
of the present embodiment is fed with the picture signals VS to
control the light-emitting diode driving circuits 34R, 34G and 34B
and the motor driving circuit 62 as will be explained
subsequently.
[0110] FIG. 14 is a flow diagram showing the operation of the
controller 35 concerning control of the light-emitting diode
driving circuits 34R, 34G and 34B and the motor driving circuit 62
depending on the type of the picture signals. In this operation,
the controller 35 first judges at step S101 whether or not the
picture signals are of the NTSC system (step S101). If the system
is the NTSC system (Y), the controller 35 controls the
light-emitting diode driving circuits 34R, 34G and 34B so that the
color temperature will be the color temperature of a white picture
for the NTSC system (such as 9300.degree.) to adjust the brightness
of light radiated from the light-emitting diodes 12R, 12G and 12B
(step S102). The controller 35 then controls the motor driving
circuit 62 so as to meet the condition of the aspect ratio of 3:4
of the NTSC system to insert the cylindrical lens 52 into the
illuminating light path of each color (step S103) to complete the
operation of FIG. 14.
[0111] If the picture signals are not of the NTSC system (step
S101; N), the controller 35 judges whether or not the picture
signals are of the hi-vision system (step S104). If the system is
the hi-vision system (Y), the controller 35 controls the
light-emitting diode driving circuits 34R, 34G and 34B so that the
color temperature will be the color temperature of a white picture
for the hi-vision system (such as 6500.degree.) to adjust the
brightness of light radiated from the light-emitting diodes 12R,
12G and 12B (step S105). The controller 35 then controls the motor
driving circuit 62 so as to meet the condition of the aspect ratio
of 9:16 of the hi-vision system to insert the cylindrical lens 51
into the illuminating light path of each color (step S106) to
complete the operation of FIG. 14
[0112] If the picture signals are not of the hi-vision system (step
S104; N), the controller 35 judges whether or not the picture
signals are those for a computer (step S107). If the picture
signals are those for a computer (Y), the controller 35 controls
the light-emitting diode driving circuits 34R, 34G and 34B so that
the color temperature will be the color temperature of a white
picture for the computer (such as 9300.degree.) to adjust the
brightness of light radiated from the light-emitting diodes 12R,
12G and 12B (step S108). The controller 35 then controls the motor
driving circuit 62 so as to meet the condition of the aspect ratio
of 3:4 of the picture for the computer to insert the cylindrical
lens 52 into the illuminating light path of each color (step S109)
to complete the operation of FIG. 14.
[0113] If the picture signals are not those for a computer (step
S107; N), the controller 35 controls the light-emitting diode
driving circuits 34R, 34G and 34B so that the color temperature
will be the color temperature of a default white picture (such as
6500.degree. or 9300.degree.) to adjust the brightness of light
radiated from the light-emitting diodes 12R, 12G and 12B (step
S110). The controller 35 then controls the motor driving circuit 62
so as to meet the condition of the default aspect ratio of 3:4 or
9:16 to insert the cylindrical lens 52 or 51 into the illuminating
light path of each color (step S111) to complete the operation of
FIG. 14.
[0114] In judging whether or not the picture signals are of the
NTSC system, hi-vision system or of the computer, horizontal or
vertical synchronization signals in the picture signals can be
detected to detect the frequency (Hz) of the horizontal or vertical
synchronization frequency.
[0115] As the color temperature of the white picture for the NTSC
system or the hi-vision system, that adopted by the Society of
Electromechanical Association of japan, for example, is used.
[0116] If additionally the television standards other than the NTSC
system or the hi-vision system, such as PAL or SECAM, are to be
met, it suffices to add steps similar to steps S101, S104 or
S107.
[0117] With the picture display device of the present embodiment,
since the switching of the cylindrical lenses 51, 52 and color
temperature adjustment of the white picture are effected in
dependence upon the discriminated type of the displayed picture, it
is possible to set the optimum illuminating state and the optimum
color temperature automatically. In addition, since the shape of
the light beam illuminated on the picture forming area is varied
automatically in dependence upon the shape of the picture forming
area of the picture display light bulb 11, it becomes possible to
reduce the variation in brightness of the displayed picture.
[0118] In the present embodiment of the picture display device, it
is also possible to provide an operation unit for entering user
commands to the controller 35 for independently adjusting the
brightness of the light radiated from the light-emitting diodes
12R, 12G and 12B and for switching the cross-sectional shape of the
light beam on the picture display light bulb 11 and in order for
the controller 35 to adjust independently the brightness of the
light radiated from the light-emitting diodes 12R, 12G and 12B or
to switch the cross-sectional shape of the light beam on the
picture display light bulb 11 in accordance with the commands from
the operating unit.
[0119] In the present embodiment of the picture display device, it
is also possible for the controller 35 to adjust the brightness of
the light radiated from the light-emitting diodes 12R, 12G and 12B,
depending on the shape of the picture forming area in the picture
display light bulb 11 as detected based on the picture signals, for
maintaining the brightness of the displayed picture in its entirety
to a pre-set value.
[0120] With the picture display device of the present embodiment,
it is also possible not to provide the light bundle shape changing
devices 60R, 60G or 60R and to provide a light source device
including plural light-emitting diodes of the second embodiment in
place of the light-emitting diodes 12R, 12g or 12b, the controller
35 then controlling the light-emitting diode driving circuits 34R,
34G or 34B to switch the light-emitting diodes driven by the light
source device 42 to switch the cross-sectional shape of the light
beam on the picture display light bulb 11.
[0121] The structure and the operation of the present embodiment
are otherwise the same as those of the first to third
embodiments.
[0122] Referring to FIGS. 15 to 17, a picture display device
according to a fifth embodiment of the present invention is
explained.
[0123] The picture display device of the present embodiment
displays a color picture in accordance with the time-divisional
color display system. FIG. 15 illustrates the structure of the
present embodiment of the picture display device. The picture
display device of the present embodiment is provided with a picture
display light bulb 11 between the synthesis prism 10 and the
projection lens 15, instead of being provided with the picture
display light bulbs 11R, 11G and 11B for respective colors of the
first embodiment.
[0124] FIG. 16 is a block diagram showing a circuit structure of
the present embodiment of the picture display device. The present
embodiment of the picture display device includes a picture signal
processing circuit 66 fed with the picture signals VS to generate
red picture signals, green picture signals and blue picture signals
associated respectively with red, green and blue pictures to
sequentially switch and output the generated picture signals. The
picture display device also includes a picture memory 67 for
temporarily storing red picture signals, green picture signals and
blue picture signals generated by the picture signal processing
circuit 66 and a light bulb driving circuit 68 connected to the
picture signal processing circuit 66 and the picture memory 67 for
driving the picture display light bulb 65.
[0125] The picture display device also includes a red
light-emitting diode driving circuit 34R, a green light-emitting
diode driving circuit 34G and a blue light-emitting diode driving
circuit 34B for driving the red light-emitting diode 12R, green
light-emitting diode 12G and the blue light-emitting diode 12B and
a controller 35 for controlling the picture signal processing
circuit 66, light bulb driving circuit 68 and the light-emitting
diode driving circuits 34R, 34G and 34B. The light-emitting diode
is indicated as LED in the drawings.
[0126] Referring to the timing chart of FIG. 17, the operation of
the picture display device of the present embodiment is explained.
The controller 35, fed with the picture signals VS, generates
timing signals for splitting a frame period or a field period into
three equal portions in timed relation to the picture signals and
sends the generated timing signals to the picture signal processing
circuit 66 and to the light bulb driving circuit 68. The picture
signal processing circuit 66 is responsive to these timing signals
to generate red picture signals, green picture signals and the blue
picture signals, and sequentially switches between these signals to
output the selected signals. These picture signals are temporarily
stored in the picture memory 67. The light bulb driving circuit 68
is responsive to the timing signals from the controller 35 to
sequentially read out the picture signals of the respective colors
from the picture memory 67 to drive the picture display light bulb
65. The result is that, in the picture display light bulb 65,
gradation pictures of red (R), green (G) and blue (B) are
sequentially switched and displayed during a frame or field period,
as shown in FIG. 19D.
[0127] The controller 35 controls the light-emitting diode driving
circuits 34R, 34G and 34B, in a time relation to the display of the
gradation pictures for red, green and blue colors in the picture
display light bulb 65, so that the light-emitting diodes 12R, 12G
and 12B will be turned on sequentially. The result is that the
light-emitting diodes 12R, 12G and 12B (indicated as LED R, LED G
and LED B in FIG. 17) are turned on in a timed relation with the
display of the gradation pictures for red, green and blue in the
picture display light bulb 65, so that the light beams of the
respective colors are sequentially switched and illuminated on the
picture display light bulb 65.
[0128] By the above operation, the red, green and blue pictures are
sequentially switched and projected on the screen 17. These
pictures are perceived by the viewer as the color picture due to
the after-image effect of the human eye. The present embodiment is
otherwise the same in structure and operation as the first
embodiment.
[0129] Referring to FIGS. 18 and 19, a picture display device of a
sixth embodiment of the present invention is explained. The picture
display device of the sixth embodiment displays a color picture in
accordance with the time-divisional display system and a digital
gradation display system, as in the fifth embodiment.
[0130] Referring first to FIGS. 18B to 18E, the principle of the
digital gradation display system is explained. The principle of the
digital gradation display system resides in representing a picture,
desired to be displayed, as shown in FIG. 18A, as a sum of plural
bit pictures (bi-level pictures) weighted as shown in FIGS. 18B to
18E. An upper portion of FIG. 18A denotes an example of the
gradation picture to be displayed, while upper portions of FIGS.
18B to 18E denote bit pictures weighted to 8:4:2:1, while lower
portions of FIGS. 18B to 18E denote the brightness of the pixels in
the pictures of the upper portions in hexadecimal notation. With
the present digital gradation display system, weighted bit picture
groups are displayed in one frame period, by controlling the light
source and the picture display light bulb for bi-level display.
Thus, the user can feel the gradation in the displayed picture by
the after-image effect proper the human visual system.
[0131] There are mainly two methods for weighting the bit picture
in the digital gradation display. One is the pulse width modulation
gradation display in which the brightness of the illuminating light
is rendered constant and weighting is by the length of the display
time of each bit picture. The other is the light intensity
modulation gradation display in which the display time of each bit
picture is rendered constant and weighting is by the brightness of
the illuminating light. These two methods may be used in
combination.
[0132] The structure of the picture display device of the present
embodiment is substantially the same as that shown in FIG. 16.
[0133] Referring to the timing chart of FIG. 18, the operation of
the picture display device of the present embodiment is explained.
FIGS. 19A to 19C show the light emission timing and volume of the
light-emitting diodes 12R, 12G and 12B, respectively. FIG. 19D
shows the display state of the picture display light bulb 65. In
the following description, it is assumed that digital gradation
representation is carried out by employing the pulse width
modulation gradation representation and light intensity modulation
gradation representation in combination. Also, in the following
description, it is assumed that bit pictures weighted to 8:4:2:1
for representing the red gradation picture are indicated as R8, R4,
R2 and R1, bit pictures weighted to 8:4:2:1 for representing the
green gradation picture are indicated as G8, G4, G2 and G1 and bit
pictures weighted to 8:4:2:1 for representing the blue gradation
picture are indicated as B8, B4, B2 and B1.
[0134] The controller 35, fed with the picture signals VS,
generates pre-set timing signals synchronized with the picture
signals VS and routes the generated signals to the picture signal
processing circuit 66 and to the light bulb driving circuit 68. The
picture signal processing circuit 66 is responsive to these timing
signals to generate picture signals of the bit pictures R8, G8, B8,
R4, G2, B1, R4, G2, B1, R4, G2, B1 to switch sequentially and
output these picture signals. These picture signals are temporarily
stored in the picture memory 67. The light bulb driving circuit 68
is responsive to the timing signals from the controller 35 t oread
out the picture signals sequentially from the picture memory 67 to
drive the picture display light bulb 65 based on these picture
signals. In the present embodiment, a 2/5-period of a frame
beginning from the leading end of the frame is split into three
equal portions for sequentially displaying bit pictures R8, G8, B8,
while the remaining period of the frame is divided into three equal
portions for sequentially displaying bit pictures R4, G2, B1, R4,
G2, B1, R4, G2, B1 as shown in FIG. 19D. Therefore, the period of
displaying the bit pictures R8, G8, B8 is twice as long as the
period of displaying the remaining bit pictures.
[0135] The controller 35 controls the light-emitting diode driving
circuits 34R, 34G and 34B, in a time relation to the display of the
gradation pictures for red, green and blue in the picture display
light bulb 65, so that the light-emitting diodes 12R, 12G and 12B
will be turned on sequentially, as shown in FIGS. 19A to 19C. The
controller 35 also controls the light-emitting diode driving
circuits 34R, 34G and 34B so that, during the period the bit
pictures 34R, 34G and 34B are displayed and during the period the
bit pictures 34R, 34G and 34B are displayed, the light emission
volumes of the light-emitting diodes 12R, 12G and 12B are equal to
one another, and so that, if the light emission volume is 1, the
light emission volume during the period the bit pictures R2, G2 and
B2 are displayed is 1/2 and the light emission volume is 1, the
light emission volume during the period the bit pictures R1, G1 and
B1 are displayed is 1/4. By the above operation, the light beams of
the plural bit pictures, weighted buy 8:4:2:1 from color to color
in each frame, are sequentially projected on the screen 17. These
pictures are perceived by the viewer as the color picture due to
the after-image effect of the human eye. The present embodiment is
otherwise the same in structure and operation as the fifth
embodiment.
[0136] FIG. 20 shows a schematic view for illustrating the
structure of a picture display device according to a seventh
embodiment of the present invention. The present embodiment of the
picture display device uses a reflection type liquid crystal light
bulb as the picture display light bulb to display a color picture
using the time-divisional color display system. Of course, a
transmission type liquid crystal light bulb as shown in FIG. 15 may
be used for the time-divisional color display system.
[0137] The present embodiment of the picture display device
includes a polarisation beam splitter 70 and a picture display
light bulb 71 employing a reflection type liquid crystal light bulb
in the fifth embodiment of the picture display device of FIG. 15,
in place of the picture display light bulb 65 employing the
transmission type liquid crystal light bulb. The polarisation beam
splitter 70 and the picture display light bulb 71 ae arrayed in
this order on the optical path of the outgoing light of the
synthesis prism 10. The polarisation beam splitter 70 has a
reflecting surface 70a transmitting the P-polarized light
(polarized light having the direction of light polarization
parallel to the incident surface) and reflecting the S-polarized
light (polarized light having the direction of light polarization
normal to the incident surface). In the present embodiment, the
projection lens 15 is arranged in a direction in which the light
from the picture display light bulb 71 proceeds after reflection on
the reflecting surface 70a of the polarisation beam splitter
70.
[0138] Similarly to the fifth embodiment, the picture display
device of the present embodiment drives the light-emitting diodes
12R, 12G and 12B and the picture display light bulb 71 in
accordance with the time-divisional color display system. The light
beams outgoing from the light-emitting diodes 12R, 12G and 12B fall
on the polarisation beam splitter 70 via relay lenses 13R, 13G and
13B and field lenses 14R, 14G and 14B. Of the light incident on the
polarisation beam splitter 70, only the P-polarized components are
transmitted through the reflective surface 70a to fall on the
picture display light bulb 71. The picture display light bulb 71,
employing the reflective liquid crystal light bulb, converts the
polarized state (polarization degree) on the pixel basis responsive
to the displayed picture by exploiting double reflection by way of
spatially modulating the incident light for reflection towards the
polarisation beam splitter 70. The polarisation beam splitter 70
reflects only the S-polarized component of the light from the
picture display light bulb 71 on its reflective surface 70a to
cause the reflected light to fall on the projection lens 15 for
projection on the transmission or reflection type screen 17 to an
enlarged scale. The present embodiment is otherwise the same in
structure and operation as the fifth embodiment.
[0139] FIG. 21 is shows schematic view for illustrating the
structure of a picture display device according to an eighth
embodiment of the present invention. The picture display device of
the present embodiment includes, for each color, a picture display
light bulb employing a reflection type liquid crystal light bulb.
The present picture display device includes a red light-emitting
diode 12R, a red relay lens 13R, a red field lens 14R, a red
polarisation beam splitter 70R and a red picture display light bulb
71R, which are linearly arranged so that, of the light reflected by
the red picture display light bulb 71R, the S-polarized light
component reflected by the red polarisation beam splitter 70R will
be incident on the surface 10R of the synthesis prism 10. The
picture display device also includes a green light-emitting diode
12G, a green relay lens 13G, a green field lens 14G, a green
polarisation beam splitter 70G and a green picture display light
bulb 71G, which are linearly arranged so that, of the light
reflected by the red picture display light bulb 71G, the
S-polarized light component reflected by the green polarisation
beam splitter 70R will be incident on the surface 10G of the
synthesis prism 10. The picture display device also includes a blue
light-emitting diode 12B, a blue relay lens 13B, a blue field lens
14B, a blue polarisation beam splitter 70B and a blue picture
display light bulb 71B, which are linearly arranged so that, of the
light reflected by the red picture display light bulb 71B, the
S-polarized light component reflected by the green polarisation
beam splitter 70B will be incident on the surface 10B of the
synthesis prism 10.
[0140] The principle of modulation by the polarisation beam
splitters 70R, 70G and 70B and the picture display light bulbs 71R,
71G and 70B is similar to that explained in connection with the
seventh embodiment. The light beams, modulated from color to color,
are synthesized by the synthesis prism 10 to be projected by the
projection lens 15 on the screen 17. The present embodiment is
otherwise the same in structure and operation as the fifth
embodiment.
[0141] FIG. 22 is shows schematic view for illustrating the
structure of a picture display device according to a ninth
embodiment of the present invention. The present embodiment of the
picture display device is of the virtual image display type and
takes the form of a head mounting display attached to the user's
head. Of course, the picture display device of the present
embodiment can be designed as the virtual image display type not
attached to the user's head.
[0142] The picture display device includes a synthesis prism 10,
picture display light bulbs 11R, 11G and 11B, light-emitting diodes
12R, 12G and 12B, relay lenses 13R, 13G and 13b and field lenses
14R, 14G and 14b, arranged in the relative disposition similar to
that of the first embodiment. The picture display device of the
present embodiment also includes a half mirror 80 arranged on the
optical path of the outgoing light beam from the synthesis prism
10, and a concave mirror 81 arranged on the optical path of the
light radiated from the synthesis prism 10 and reflected by the
half mirror 80. The concave mirror 81 is also used as a half
mirror. These components are held by a suitable holder and arranged
in a casing 16.
[0143] With the present embodiment of the picture display device,
the light beams modulated from color to color as in the first
embodiment are synthesized by the synthesis prism 10 and partially
reflected by the half mirror 80 to fall on the concave mirror 81
where the light is partially reflected to fall on the half mirror
80 and is partially transmitted to be projected on an eye 84 of the
viewer via aperture 82. Thus, an enlarged virtual image 85,
corresponding to the picture synthesized by the synthesis prism 10,
can be seen by the viewer along with the forward background. The
present embodiment is otherwise the same in structure and operation
as the first embodiment.
[0144] FIG. 23 shows a schematic view for illustrating the
structure of a picture display device according to a tenth
embodiment of the present invention. In the present embodiment, the
invention is applied to a light exposure device in which a mask
pattern (corresponding to the picture in the present invention) is
projected for light exposure on a photoresist placed on a
semiconductor wafer. The present embodiment of the light exposure
device includes a light-emitting diode 91 for radiating the light
sensitive to a photoresist (visible light or ultraviolet light), a
collector lens 92 for collecting the outgoing light of the
light-emitting diode 91, and a fly-eye lens 93 for homogenizing the
intensity of illumination of the light after passing through the
fly-eye lens 93. The light exposure device also includes a
condenser lens 94 for condensing the light passed through the
fly-eye lens 92 for illumination on a mask 95 having a pre-set
pattern formed thereon (corresponding to the spatial modulation
means of the present invention) and a projection lens 96 for
projecting the light passed through the mask 95 on the photoresist
on the semiconductor wafer 97. In the present embodiment, the light
radiating portion of the light-emitting diode 91 is shaped
equivalently to the picture forming area of the mask 95 so that the
light beam illuminated on the picture forming area of the mask 95
will be shaped equivalently to the picture forming area. In the
present embodiment the outgoing light of the light-emitting diode
91 can be adjusted in brightness, as in the first embodiment.
[0145] In the present light exposure device, the light radiated by
the light-emitting diode 91 is illuminated on the mask 95 via the
collector lens 92, fly-eye lens 93 and the condenser lens 94. The
light spatially modulated by the mask 95 is projected by the
projection lens 96 on the photoresist of the semiconductor wafer 97
for exposing the photoresist to light. The light exposure device of
the present embodiment may be an equal-size light exposure device
or a step type device for contraction projection light
exposure.
[0146] With the present embodiment of the light exposure device, in
which a light-emitting diode 91 is used as a light source, the
light source may be prolonged in service life and the power
consumption may be reduced, while the light exposure device may be
reduced in size. Moreover, with the present embodiment of the light
exposure device, the light radiating portion of the light-emitting
diode 91 is shaped in keeping with the profile of the picture
forming area of the mask 95 so that the light beam illuminated on
the picture forming area of the mask 95 is shaped equivalently to
the picture forming area, thus improving the light utilization
efficiency. Moreover, the power consumption is further reduced to
render the device more compact. In addition, with the present
embodiment of the light exposure device, since the outgoing light
of the light-emitting diode 91 can be adjusted in brightness, the
light exposure volume can be adjusted easily.
[0147] The present invention is not limited to the above-described
illustrative embodiments. For example, not only the synthesis prism
10 but also the dichroic mirror or a color filter transmitting or
reflecting particular wavelength components may be used for
synthesizing pictures of respective colors.
[0148] As spatial modulation means, a liquid crystal light bulb
employing a dielectric liquid crystal or a high-molecular
dispersion liquid crystal may be used in addition to those given in
the embodiments. Moreover, the spatial modulation means for
controlling the light reflection, transmission or diffraction on
the pixel basis by mechanical means for spatial light modulation
may also be used.
[0149] In the present embodiment, a light-emitting diode emitting
red, green or blue light is used. In this case. The picture display
light bulb is designed to be driven based in color signals
corresponding to the color of the radiated light of the
light-emitting diode.
[0150] Although the two cylindrical lenses are switched in the
third and fourth embodiments for switching the cross-sectional
profile of the light beam, one or not less than three cylindrical
lenses may be used to vary the cross-sectional area of the light
beam. If a sole cylindrical lens is used, the cross-sectional
profile of the light beam is switched depending on whether the
cylindrical lens is to be inserted into the optical path. The
optical component used for varying the cross-sectional profile of
the light beam may also be a mirror having a cylindrical surface,
prism or other element, without being limited to a cylindrical
lens. The cross-sectional profile of the light beam may also be
varied continuously by arranging the cylindrical lens and the lens
having a cylindrical recessed surface in a direction along the
proceeding direction of the illuminating light beam and/or the
lenses may be varied in the mounting positions for continuously
varying the cross-sectional profile of the light beam.
[0151] The light-emitting diode having a rectangular light
radiating portion (light emitting surface) as that used in the
first embodiment may be used, and the profile of the light beam
radiated from the light-emitting diode may be varied using an
optical element such as a cylindrical lens, as in the first
embodiment, for selectively generating plural sorts of the light
beams having different values of the aspect ratio.
[0152] The respective embodiments may be suitably combined to
constitute a picture display device.
[0153] In the above-described fifth and sixth embodiments, the
color picture is displayed in accordance with the time-divisional
color display system. In the time-divisional color display system,
different colors are displayed time-divisionally for color
synthesis for displaying a color picture. That is, a frame which is
the display time for a picture is divided into three portions and
pictures of respective colors of red, green and blue are
sequentially outputted to the picture display light bulbs, at the
same time as the light beams of corresponding colors are
sequentially illuminated on the picture display light bulbs to
display a color picture.
[0154] However, if the pictures of the red, green and blue colors
are time-divisionally displayed to effect color synthesis to
display a color picture, the light emitting time of each color is
one-third the frame period. In addition, the pictures of respective
colors are repeatedly turned on and off. Thus, there are occasions
wherein, during eye blinking time or when the eye follows a moving
object, color synthesis cannot be achieved.
[0155] That is, during eye blinking time, so-called color splitting
is likely to be produced. Otherwise, if an eye follows a moving
object, a so-called edge chromatic phenomenon is likely to be
incurred, as shown in FIG. 24. FIG. 24 shows the state in which
color synthesis of red, green and blue colors leads to red or
yellow portions and blue or cyan portions, instead of to a white
color portion, at an end or at the opposite end by the edge
chromatic phenomenon.
[0156] The color splitting or the edge chromatic phenomenon can be
suppressed by shortening the continuous display time of a
monochromatic picture. It can be clarified by the comparison
between FIG. 24 and FIG. 25.
[0157] An illustrative method to suppress the color-splitting or
the edge chromatic phenomenon is explained by referring to FIG. 26
and to a timing chart shown in FIG. 33.
[0158] In FIGS. 26 to 33, similarly to FIG. 19, A to C denote the
light emission timing and volume of the light-emitting diodes 12R,
12G and 12B, respectively, while D denotes the display state of the
picture display light bulb 65. As in FIG. 19, bit pictures weighted
to 8:4:2:1 for representing the red gradation picture are indicated
as R8, R4, R2 and R1, bit pictures weighted to 8:4:2:1 for
representing the green gradation picture are indicated as G8, G4,
G2 and G1 and bit pictures weighted to 8:4:2:1 for representing the
blue gradation picture are indicated as B8, B4, B2 and B1.
[0159] Also, in the following description, the combination of the
red gradation picture, having the weighting equal to 1, green
gradation picture, having the weighting equal to 1 and the blue
gradation picture, having the weighting equal to 1, is termed a bit
plane BP1 having the weighting equal to 1. Similarly, the
combination of the red gradation picture, having the weighting
equal to 2, green gradation picture, having the weighting equal to
2 and the blue gradation picture, having the weighting equal to 2,
is termed a bit plane BP2 having the weighting equal to 2.
Likewise, the combination of the red gradation picture, having the
weighting equal to 4, green gradation picture, having the weighting
equal to 4 and the blue gradation picture, having the weighting
equal to 4, is termed a bit plane BP3 having the weighting equal to
4, while the combination of the red gradation picture, having the
weighting equal to 8, green gradation picture, having the weighting
equal to 8 and the blue gradation picture, having the weighting
equal to 8, is termed a bit plane BP4 having the weighting equal to
8.
[0160] First, an example of FIG. 26 is explained. In the example of
FIG. 26, pulse width modulation gradation representation is used
for digital gradation representation. The bit plane BP1, having the
weighting equal to 1, bit plane BP2, having the weighting equal to
2, bit plane BP3, having the weighting equal to 4 and the bit plane
BP4 having the weighting equal to 8 are displayed in this
order.
[0161] That is, in the example of FIG. 26, pictures R1, G1 and B1,
each having a pulse width equal to .tau., are displayed in this
order as the bit plane BP1 having the weighting equal to 1. Then,
pictures R2, G2 and B2, each having a pulse width equal to 2.tau.,
are displayed in this order as the bit plane BP2 having the
weighting equal to 2.
[0162] Next, pictures R4, G4 and B4, each having a pulse width
equal to 4.tau., are displayed in this order as the bit plane BP3
having the weighting equal to 4. Finally, pictures R8, G8 and B8,
each having a pulse width equal to 8.tau., are displayed in this
order as the bit plane BP4 having the weighting equal to 8.
[0163] If this display is done by the picture display device shown
in FIG. 16, the controller 35 generates pre-set timing signals
synchronized with the input picture signals VS, and sends the
timing signals to the picture signal processing circuit 66 and to
the light bulb driving circuit 68. The picture signal processing
circuit 66 is responsive to these timing signals to generate
picture signals of bit pictures R1, G1, B1, R2, G2, B2, R4, G4, B4,
R8, G8 and B8 each frame and sequentially switches and outputs the
picture signals. These picture signals are transiently stored on
the picture memory 67. The light bulb driving circuit 68 is
responsive to the timing signals from the controller 35 to read out
sequentially the picture signals of the bit pictures from the
picture memory 67 to drive the 65 based on these picture
signals.
[0164] At this time, the bit pictures B1, R2, G2, B2, R4, G4, B4,
R8, G8 and B8 are sequentially displayed beginning from the leading
end of each frame, as shown in FIG. 26D. Since the pulse width
modulation gradation representation is used in the present example,
the period during which the bit pictures R2, G2 and 32 are
displayed is 2.tau., the period during which the bit pictures R4,
G4 and B4 are displayed is 4.tau. and the period during which the
bit pictures R8, G8 and B8 are displayed is 8.tau., where .tau. is
the period during which each of the bit pictures R1, G1 and B13 is
displayed.
[0165] Referring to FIGS. 26A to 26C, the controller 35 controls
the light-emitting diode driving circuits 34R, 34G and 34B, in
timed relation to the timing of display of the red, green and blue
bit pictures on the picture display light bulb 65, so that the
light-emitting diodes 12R, 12G and 12B will be turned on
sequentially. The controller 35 controls the light-emitting diode
driving circuits 34R, 34G and 34B so that the light volume from the
light-emitting diodes 12R, 12G and 12B will be the light volume
perceived as being agreeable to the human eye.
[0166] By the above operations, the light beams of the plural bit
pictures, weighted from color to color in each frame, are
sequentially projected on the screen 17. The bit pictures are
perceived as being a color picture by the viewer because of the
after-image effect proper to the human visual system. When
time-divisionally displaying plural monochromatic pictures, bit
pictures with different display colors are sequentially displayed
in such a manner as to evade continuous display of the bit colors
of the same colors for shortening the time during which the
monochromatic pictures are displayed continuously. This eliminates
the occurrence of the color splitting or the edge chromatic
phenomenon.
[0167] Next, an example shown in FIG. 27 is explained. In the
example of FIG. 27, digital gradation representation is done by the
pulse width modulation gradation representation. Thus, a bit plane
BP1 with the weighting equal to 1, a bit plane BP3 with the
weighting equal to 4, a bit plane BP2 with the weighting equal to
2, a bit plane BP4 with the weighting equal to 8 are displayed in
this order.
[0168] That is, in the example of FIG. 27, pictures R1, G1 and B1,
each having a pulse width equal to 1, are displayed in this order
as the bit plane BP1 having the weighting equal to 1. Then,
pictures R4, G4 and B4, each having a pulse width equal to .tau.,
are displayed in this order as the bit plane BP3 having the
weighting equal to 4. Next, pictures R2, G2 and B2, each having a
pulse width equal to 2.tau., are displayed in this order as the bit
plane BP2 having the weighting equal to 2. Then, pictures R8, G8
and B8, each having a pulse width equal to 8.tau., are displayed in
this order as the bit plane BP4 having the weighting equal to
8.
[0169] When doing this display by the picture display device shown
in FIG. 16, the controller 35 generates a pre-set timing signal in
a timed relation to the input picture signal VS and sends the
timing signal to the picture signal processing circuit 66 and to
the light bulb driving circuit 68. The picture signal processing
circuit 66 is responsive to the timing signals to generate bit
pictures R1, G1, B1, R4, G4, B4, R2, G2, B2, R8, G8 and B8 from
frame to frame and sequentially switches and outputs the picture
signals. The picture signals are transiently stored in the picture
memory 67. The light bulb driving circuit 68 is responsive to the
timing signals from the controller 35 to read out sequentially the
picture signals of the bit pictures from the picture memory 67 to
drive the picture signal processing circuit 66 based on these
picture signals.
[0170] In the present example, the bit pictures R1, G1, B13, R4,
G4, B4, R2, G2, B2, R8, G8 and B8 are sequentially displayed
beginning from the leading end of each frame, as shown in FIG. 27D.
Since the pulse width modulation gradation representation is used
in the present example, the period during which the bit pictures
R2, G2 and B2 are displayed is 2.tau., the period during which the
bit pictures R4, G4 and B4 are displayed is 4.tau. and the period
during which the bit pictures R8, G8 and B8 are displayed is
8.tau., where .tau. is the period during which each of the bit
pictures R1, G1 and B1 is displayed.
[0171] Referring to FIGS. 27A to 27C, the controller 35 controls
the light-emitting diode driving circuits 34R, 34G and 34B, in
timed relation to the timing of display of the red, green and blue
bit pictures on the picture display light bulb 65, so that the
light-emitting diodes 12R, 12G and 12B will be turned on
sequentially. The controller 35 controls the light-emitting diode
driving circuits 34R, 34G and 34B so that the light volume from the
light-emitting diodes 12R, 12G and 12B will be the light volume
perceived as being agreeable to the human eye.
[0172] By the above operations, the light beams of the plural bit
pictures, weighted from color to color in each frame, are
sequentially projected on the screen 17. The bit pictures are
perceived as being a color picture by the viewer because of the
after-image effect proper to the human visual system. When
time-divisionally displaying plural monochromatic pictures, bit
pictures with different display colors are sequentially displayed
in such a manner as to evade contiguous display of the bit colors
of the same colors, thus shortening the time during which the
monochromatic pictures are displayed continuously. This eliminates
the occurrence of the color splitting or the edge chromatic
phenomenon.
[0173] Next, an example shown in FIG. 28 is explained. In the
example of FIG. 28, digital gradation representation is by the
pulse width modulation gradation representation. Thus, the R1, G1,
B1, R2, G2, B2, R4, G4, B4, R8, G8 and B8 making up the bit planes
BP1, BP2, BP4, BP8 are interchanged in sequence for display.
[0174] That is, in the example of FIG. 28, for displaying a frame,
a red bit picture R1 having a pulse width .tau., a green bit
picture G2 having a pulse width 2.tau., a blue bit picture B8
having a pulse width 8.tau., a red bit picture R4 having a pulse
width 4.tau., a green bit picture G8 having a pulse width 8.tau., a
blue bit picture B4 having a pulse width 4.tau., a red bit picture
R2 having a pulse width 2.tau., a blue bit picture B1 having a
pulse width .tau., a green bit picture G4 having a pulse width
4.tau., a red bit picture R8 having a pulse width 8.tau., a blue
bit picture B2 having a pulse width 2.tau., and a green bit picture
G1 having a pulse width .tau. are displayed in this order.
[0175] When doing this display by the picture display device shown
in FIG. 16, the controller 35 generates a pre-set timing signal in
a timed relation to the input picture signal VS and sends the
timing signal to the picture signal processing circuit 66 and to
the light bulb driving circuit 68. The picture signal processing
circuit 66 is responsive to the timing signals to generate bit
pictures R1, G2, B8, R4, G8, B4, R2, B1, G4, R8, B2 and G1 from
frame to frame and sequentially switches and outputs the picture
signals. The picture signals are transiently stored in the picture
memory 67. The light bulb driving circuit 68 is responsive to the
timing signals from the controller 35 to read out sequentially the
picture signals of the bit pictures from the picture memory 67 to
drive the picture display light bulb 65 based on these picture
signals.
[0176] At this time, the bit pictures R1, G2, B8, R4, G8, B4, R2,
B1, G4, R8, B2 and G1 are sequentially displayed beginning from the
leading end of each frame, as shown in FIG. 28D. Since the pulse
width modulation gradation representation is used in the present
example, the period during which the bit pictures R2, G2 and B2 are
displayed is 2.tau., the period during which the bit pictures R4,
G4 and B4 are displayed is 4.tau. and the period during which the
bit pictures R8, G8 and B8 are displayed is 8.tau., where .tau. is
the period during which each of the bit pictures R1, G1 and B1 is
displayed.
[0177] Referring to FIGS. 28A to 28C, the controller 35 controls
the light-emitting diode driving circuits 34R, 34G and 34B, in
timed relation to the timing of display of the red, green and blue
bit pictures on the picture display light bulb 65, so that the
light-emitting diodes 12R, 12G and 12B will be turned on
sequentially. The controller 35 controls the light-emitting diode
driving circuits 34R, 34G and 34B so that the light volume from the
light-emitting diodes 12R, 12G and 12B will be the light volume
perceived as being agreeable to the human eye.
[0178] By the above operations, the light beams of the plural bit
pictures, weighted from color to color in each frame, are
sequentially projected on the screen 17. The bit pictures are
perceived as being a color picture by the viewer because of the
after-image effect proper to the human visual system. When
time-divisionally displaying plural monochromatic pictures, bit
pictures with different display colors are sequentially displayed
in such a manner as to evade contiguous display of the bit colors
of the same colors, thereby shortening the time during which the
monochromatic pictures are displayed continuously. This eliminates
the occurrence of the color splitting or the edge chromatic
phenomenon.
[0179] Next, an example shown in FIG. 29 is explained. In the
example of FIG. 29, digital gradation representation is by the
pulse width modulation gradation representation. Thus, the bit
pictures R4, G4 and B4 are displayed in two installments, while the
bit pictures R8, G8 and B8 are displayed in four installments.
[0180] That is, in the example of FIG. 29, a red bit picture R8
with a pulse width 2.tau., a green bit picture G8 with a pulse
width 2.tau. and a blue bit picture B8 with a pulse width 2.tau.
are displayed in this order. Then, a red bit picture R4 with a
pulse width 2.tau., a green bit picture G4 with a pulse width
2.tau. and a blue bit picture B4 with a pulse width 2.tau. are
displayed in this order. Next, a red bit picture R8 with a pulse
width 2.tau., a green bit picture G8 with a pulse width 2.tau. and
a blue bit picture B8 with a pulse width 2.tau. are displayed in
this order. Then, a red bit picture R2 with a pulse width 2.tau., a
green bit picture G2 with a pulse width 2.tau. and a blue bit
picture B2 with a pulse width 2.tau. are displayed in this order.
Then, a red bit picture R1 with a pulse width .tau., a green bit
picture G1 with a pulse width .tau. and a blue bit picture B1 with
a pulse width .tau. are displayed in this order. Then, a red bit
picture R8 with a pulse width 2.tau., a green bit picture G8 with a
pulse width 2.tau. and a blue bit picture B8 with a pulse width
2.tau. are displayed in this order. Next, a red bit picture R4 with
a pulse width 2.tau., a green bit picture G4 with a pulse width
2.tau. and a blue bit picture B4 with a pulse width 2.tau. are
displayed in this order. Then, a red bit picture R8 with a pulse
width 2.tau., a green bit picture G8 with a pulse width 2.tau. and
a blue bit picture B8 with a pulse width 2.tau. are displayed in
this order.
[0181] If this display is done by the picture display device shown
in FIG. 16, the controller 35 generates pre-set timing signals
synchronized with the input picture signals VS, and sends the
timing signals to the picture signal processing circuit 66 and to
the light bulb driving circuit 68. The picture signal processing
circuit 66 is responsive to these timing signals to generate
picture signals of bit pictures R8, G8, B8, R4, G4, B4, R8, G8, B8,
R2, G2, B2, R1, G1, B1, R8, G8, B8, R4, G4, B4, R8, G8, B8 each
frame and sequentially switches and outputs the picture signals.
These picture signals are transiently stored on the picture memory
67. The light bulb driving circuit 68 is responsive to the timing
signals from the controller 35 to read out sequentially the picture
signals of the bit pictures from the picture memory 67 to drive the
picture display light bulb 65 based on these picture signals.
[0182] At this time, the bit pictures R8, G8, B8, R4, G4, B4, R8,
G8, B8, R2, G2, B2, R1, G1, B1, R8, G8, B8, R4, G4, B4, R8, G8, B8
are sequentially displayed beginning from the leading end of each
frame, as shown in FIG. 29D. Since the pulse width modulation
gradation representation is used in the present example, and the
bit pictures R4, G4 and B4 are displayed in two installments, while
the bit pictures R8, G8 and B8 are displayed in four installments,
the period during which the bit pictures R2, G2 and B2 are
displayed is 2.tau., the period during which the bit pictures R2,
G2, B2, R4, G4, B4, R8, G8, B8 are displayed is 4.tau. where .tau.
is the period during which each of the bit pictures R1, G1 and B1
is displayed.
[0183] Referring to FIGS. 29A to 29C, the controller 35 controls
the light-emitting diode driving circuits 34R, 34G and 34B, in
timed relation to the timing of display of the red, green and blue
bit pictures on the picture display light bulb 65, so that the
light-emitting diodes 12R, 12G and 12B will be turned on
sequentially. The controller 35 controls the light-emitting diode
driving circuits 34R, 34G and 34B so that the light volume from the
light-emitting diodes 12R, 12G and 12B will be the light volume
perceived as being agreeable to the human eye.
[0184] By the above operations, the light beams of the plural bit
pictures, weighted from color to color in each frame, are
sequentially projected on the screen 17. The bit pictures are
perceived as being a color picture by the viewer because of the
after-image effect proper to the human visual system. When
time-divisionally displaying plural monochromatic pictures, bit
pictures with different display colors are sequentially displayed
in such a manner as to evade contiguous display of the bit colors
of the same colors, thereby shortening the time during which the
monochromatic pictures are displayed continuously. This eliminates
the occurrence of the color splitting or the edge chromatic
phenomenon. Moreover, since the variations in the display periods
of the bit pictures in the present embodiment may be reduced, the
picture displayed is of a higher picture quality.
[0185] Next, an example shown in FIG. 30 is explained. In the
example of FIG. 30, digital gradation representation is by the
pulse width modulation gradation representation. Thus, the bit
pictures R4, G4 and B4 are displayed in two installments, while the
bit pictures R8, G8 and B8 are displayed in four installments, as
in the example of FIG. 29. In addition, in the present example, the
bit pictures R1, G1, B1, R2, G2, B2, R4, G4, B4, R8, G8, B8 are
displayed in an interchanged sequence.
[0186] That is, in the example of FIG. 30, a red bit picture R8
with a pulse width 2.tau., a green bit picture G4 with a pulse
width 2.tau. and a blue bit picture B2 with a pulse width 2.tau.
are displayed in this order. Then, a red bit picture R4 with a
pulse width 2.tau., a green bit picture G8 with a pulse width
2.tau. and a blue bit picture B4 with a pulse width 2.tau. are
displayed in this order. Next, a red bit picture R8 with a pulse
width 2.tau., a green bit picture G2 with a pulse width 2.tau. and
a blue bit picture B8 with a pulse width 2.tau. are displayed in
this order. Then, a red bit picture R2 with a pulse width 2.tau., a
green bit picture G8 with a pulse width 2.tau. and a blue bit
picture B8 with a pulse width 2.tau. are displayed in this order.
Then, a red bit picture R1 with a pulse width .tau., a green bit
picture G1 with a pulse width .tau. and a blue bit picture B1 with
a pulse width .tau. are displayed in this order. Then, a red bit
picture R8 with a pulse width 2.tau., a green bit picture G8 with a
pulse width 2.tau. and a blue bit picture B4 with a pulse width
2.tau. are displayed in this order. Next, a red bit picture R4 with
a pulse width 2.tau., a green bit picture G4 with a pulse width
2.tau. and a blue bit picture B8 with a pulse width 2.tau. are
displayed in this order. Then, a red bit picture R8 with a pulse
width 2.tau., a green bit picture G8 with a pulse width 2.tau. and
a blue bit picture B8 with a pulse width 2.tau. are displayed in
this order.
[0187] If this display is done by the picture display device shown
in FIG. 16, the controller 35 generates pre-set timing signals
synchronized with the input picture signals VS, and sends the
timing signals to the picture signal processing circuit 66 and to
the light bulb driving circuit 68. The picture signal processing
circuit 66 is responsive to these timing signals to generate
picture signals of bit pictures R8, G4, B2, R4, G8, B4, R8, G2, B8,
R2, G8, B8, R1, G1, B1, R8, G8, B8, R4, G4, B4, R8, G8, B8 each
frame and sequentially switches and outputs the picture signals.
These picture signals are transiently stored on the picture memory
67. The light bulb driving circuit 68 is responsive to the timing
signals from the controller 35 to read out sequentially the picture
signals of the bit pictures from the picture memory 67 to drive the
picture display light bulb 65 based on these picture signals.
[0188] At this time, the bit pictures R8, G4, B2, R4, G8, B4, R8,
G2, B8, R2, G8, B8, R1, G1, B1, R8, G8, B4, R4, G4, B8, R8, G8, B8
are sequentially displayed beginning from the leading end of each
frame, as shown in FIG. 30D. Since the pulse width modulation
gradation representation is used in the present example, and the
bit pictures R4, G4 and B4 are displayed in two installments, while
the bit pictures R8, G8 and B8 are displayed in four installments,
the period during which the bit pictures R2, G2, B2, R4, G4, B4,
R8, G8, B8 are displayed is 2.tau. where .tau. is the period during
which each of the bit pictures R1, G1 and B1 is displayed.
[0189] Referring to FIGS. 30A to 30C, the controller 35 controls
the light-emitting diode driving circuits 34R, 34G and 34B, in
timed relation to the timing of display of the red, green and blue
bit pictures on the picture display light bulb 65, so that the
light-emitting diodes 12R, 12G and 12B will be turned on
sequentially. The controller 35 controls the light-emitting diode
driving circuits 34R, 34G and 34B so that the light volume from the
light-emitting diodes 12R, 12G and 12B will be the light volume
perceived as being agreeable to the human eye.
[0190] By the above operations, the light beams of the plural bit
pictures, weighted from color to color in each frame, are
sequentially projected on the screen 17. The bit pictures are
perceived as being a color picture by the viewer because of the
after-image effect proper to the human visual system. When
time-divisionally displaying plural monochromatic pictures, bit
pictures with different display colors are sequentially displayed
in such a manner as to evade contiguous display of the bit colors
of the same colors, thereby reducing the time during which the
monochromatic pictures are displayed continuously. This eliminates
the occurrence of the color splitting or the edge chromatic
phenomenon. Moreover, since the variations in the display periods
of the bit pictures in the present embodiment may be reduced, the
picture displayed is of a higher picture quality.
[0191] Next, an example shown in FIG. 31 is explained. In the
example of FIG. 31, digital gradation representation is by the
pulse width modulation gradation representation. Thus, a bit plane
BP1 with the weighting equal to 1, a bit plane BP2 with the
weighting equal to 2, a bit plane BP3 with the weighting equal to 4
and a bit plane BP4 with the weighting equal to 8 are displayed in
this order.
[0192] That is, for displaying a frame in the example of FIG. 31,
pictures R1, G1 and B1, each having a light emission volume set to
1, are displayed in this order as a bit plane BP1 having a
weighting equal to 1. Then, pictures R2, G2 and B2, each having a
light emission volume set to 2I, are displayed in this order as a
bit plane BP2 having a weighting equal to 2, and pictures R4, G4
and B4, each having a light emission volume set to 4I, are
displayed in this order as a bit plane BP3 having a weighting equal
to 4. Finally, pictures R8, G8 and B8, each having a light emission
volume set to 8I, are displayed in this order as a bit plane BP4
having a weighting equal to 8.
[0193] If this display is done by the picture display device shown
in FIG. 16, the controller 35 generates pre-set timing signals
synchronized with the input picture signals VS, and sends the
timing signals to the picture signal processing circuit 66 and to
the light bulb driving circuit 68. The picture signal processing
circuit 66 is responsive to these timing signals to generate
picture signals of bit pictures R1, G1, B1, R2, G2, B2, R4, G4, B4,
R8, G8, B8 each frame and sequentially switches and outputs the
picture signals. These picture signals are transiently stored on
the picture memory 67. The light bulb driving circuit 68 is
responsive to the timing signals from the controller 35 to read out
sequentially the picture signals of the bit pictures from the
picture memory 67 to drive the picture display light bulb 65 based
on these picture signals.
[0194] In the present example, the bit pictures R1, G1, B1, R2, G2,
B2, R4, G4, B4, R8, G8, B8 are sequentially displayed beginning
from the leading end of each frame, as shown in FIG. 31D. The
display periods for the bit pictures R1, G1, B1, R2, G2, B2, R4,
G4, B4, R8, G8, B8 are all of the same period .tau..
[0195] Referring to FIGS. 31A to 31C, the controller 35 controls
the light-emitting diode driving circuits 34R, 34G and 34B, in
timed relation to the timing of display of the red, green and blue
bit pictures on the picture display light bulb 65, so that the
light-emitting diodes 12R, 12G and 12B will be turned on
sequentially. Since the present embodiment is of the light
intensity modulation gradation representation system, the
controller 35 controls the light-emitting diode driving circuits
34R, 34G and 34B so that the light emission volume of the
light-emitting diodes 12R, 12G and 12B for displaying the bit
pictures R2, G2 and B2 will be 2I, the light emission volume of the
light-emitting diodes 12R, 12G and 12B for displaying the bit
pictures R4, G4 and B4 will be 4I and the light emission volume of
the light-emitting diodes 12R, 12G and 12B for displaying the bit
pictures R8, G8 and B8 will be 8I, where I is the light emission
volume for displaying the bit pictures R1, G1 and B1. The light
emission volume ratio of the light-emitting diodes 12R, 12G and 12B
can be made variable depending on the human luminosity and liking
of the user.
[0196] By the above operations, the light beams of the plural bit
pictures, weighted from color to color in each frame, are
sequentially projected on the screen 17. The bit pictures are
perceived as being a color picture by the viewer because of the
after-image effect proper to the human visual system. When
time-divisionally displaying plural monochromatic pictures, bit
pictures with different display colors are sequentially displayed
in such a manner as to evade continuous display of the bit colors
of the same colors for shortening the time during which the
monochromatic pictures are displayed contiguously. This reduces the
occurrence of the color splitting or the edge chromatic
phenomenon.
[0197] Then, an example shown in FIG. 32 is explained. In the
example of FIG. 32, digital gradation representation is by the
pulse width modulation gradation representation. Thus, a bit plane
BP1 with the weighting equal to 1, a bit plane BP3 with the
weighting equal to 4, a bit plane BP2 with the weighting equal to
2, and a bit plane BP4 with the weighting equal to 8 are displayed
in this order.
[0198] That is, for displaying a frame in the example of FIG. 32,
pictures R1, G1 and B1, each having a light emission volume set to
I, are displayed in this order as a bit plane BP1 having a
weighting equal to 1. Then, pictures R4, G4 and B4, each having a
light emission volume set to 4I, are displayed in this order as a
bit plane BP3 having a weighting equal to 4, and pictures R2, G2
and B2, each having a light emission volume set to 2I, are
displayed in this order as a bit plane BP2 having a weighting equal
to 2. Finally, pictures R8, G8 and B8, each having a light emission
volume set to 8I, are displayed in this order as a bit plane BP4
having a weighting equal to 8.
[0199] If this display is done by the picture display device shown
in FIG. 16, the controller 35 generates pre-set timing signals
synchronized with the input picture signals VS, and sends the
timing signals to the picture signal processing circuit 66 and to
the light bulb driving circuit 68. The picture signal processing
circuit 66 is responsive to these timing signals to generate
picture signals of bit pictures R1, G1, B1, R4, G4, B4, R2, G2, B2,
R8, G8, B8 each frame and sequentially switches and outputs the
picture signals. These picture signals are transiently stored on
the picture memory 67. The light bulb driving circuit 68 is
responsive to the timing signals from the controller 35 to read out
sequentially the picture signals of the bit pictures from the
picture memory 67 to drive the picture display light bulb 65 based
on these picture signals.
[0200] In the present example, the bit pictures R1, G1, B1, R4, G4,
B4, R2, G2, B2, R8, G8, B8 are sequentially displayed beginning
from the leading end of each frame, as shown in FIG. 32D. The
display periods for the bit pictures R1, G1, B1, R4, G4, B4, R2,
G2, B2, R8, G8, B8 are all of the same period .tau..
[0201] Referring to FIGS. 32A to 32C, the controller 35 controls
the light-emitting diode driving circuits 34R, 34G and 34B, in
timed relation to the timing of display of the red, green and blue
bit pictures on the picture display light bulb 65, so that the
light-emitting diodes 12R, 12G and 12B will be turned on
sequentially. Since the present embodiment is of the light
intensity modulation gradation representation system, the
controller 35 controls the light-emitting diode driving circuits
34R, 34G and 34B so that the light emission volume of the
light-emitting diodes 12R, 12G and 12B for displaying the bit
pictures R2, G2 and B2 will be 2I, the light emission volume of the
light-emitting diodes 12R, 12G and 12B for displaying the bit
pictures R4, G4 and B4 will be 4I and the light emission volume of
the light-emitting diodes 12R, 12G and 12B for displaying the bit
pictures R8, G8 and B8 will be 8I, where I is the light emission
volume for displaying the bit pictures R1, G1 and B1. The light
emission volume ratio of the light-emitting diodes 12R, 12G and 12B
can also be varied depending on the human luminosity and liking of
the user.
[0202] By the above operations, the light beams of the plural bit
pictures, weighted from color to color in each frame, are
sequentially projected on the screen 17. The bit pictures are
perceived as being a color picture by the viewer because of the
after-image effect proper to the human visual system. When
time-divisionally displaying plural monochromatic pictures, bit
pictures with different display colors are sequentially displayed
in such a manner as to evade contiguous display of the bit colors
of the same colors. This shortens the time during which the
monochromatic pictures are displayed continuously and hence reduces
the occurrence of the color splitting or the edge chromatic
phenomenon.
[0203] Then, an example shown in FIG. 33 is explained. In the
example of FIG. 33, digital gradation representation is by the
pulse width modulation gradation representation. Thus, bit pictures
R1, G1, B1, R2, G2, B2, R4, G4, B4, R8, G8, B8, making up the bit
planes B1 to B4, are displayed in interchanged sequence.
[0204] That is, for displaying a frame in the example of FIG. 33, a
red picture R1 with a light emission volume of I, a green picture
G4 with an light emission volume of 4I, a blue picture B2 with a
light emission volume of 2I, a red picture R2 with an light
emission volume of 2I, a green picture G2 with an light emission
volume of 2I, a blue picture B1 with an light emission volume of I,
a red picture R4 with an light emission volume of 4I, a green
picture G1 with an light emission volume of I, a blue picture B8
with an light emission volume of 8I, a red picture R8 with an light
emission volume of 8I, a green picture G8 with an light emission
volume of 8I, and a blue picture B4 with a light emission volume of
4I, are displayed in this order.
[0205] If this display is done by the picture display device shown
in FIG. 16, the controller 35 generates pre-set timing signals
synchronized with the input picture signals VS, and sends the
timing signals to the picture signal processing circuit 66 and to
the light bulb driving circuit 68. The picture signal processing
circuit 66 is responsive to these timing signals to generate
picture signals of bit pictures R1, G4, B2, R2, G2, B1, R4, G1, B8,
R8, G8, B4 each frame and sequentially switches and outputs the
picture signals. These picture signals are transiently stored on
the picture memory 67. The light bulb driving circuit 68 is
responsive to the timing signals from the controller 35 to read out
sequentially the picture signals of the bit pictures from the
picture memory 67 to drive the picture display light bulb 65 based
on these picture signals.
[0206] In the present example, the bit pictures R1, G4, B2, R2, G2,
B1, R4, G1, B8, R8, G8, B4 are sequentially displayed beginning
from the leading end of each frame, as shown in FIG. 33D. The
display periods for the bit pictures R1, G4, B2, R2, G2, B1, R4,
G1, B8, R8, G8, B4 are all of the same period .tau..
[0207] Referring to FIGS. 33A to 33C, the controller 35 controls
the light-emitting diode driving circuits 34R, 34G and 34B, in
timed relation to the timing of display of the red, green and blue
bit pictures on the picture display light bulb 65, so that the
light-emitting diodes 12R, 12G and 12B will be turned on
sequentially. Since the present embodiment is of the light
intensity modulation gradation representation system, the
controller 35 controls the light-emitting diode driving circuits
34R, 34G and 34B so that the light emission volume of the
light-emitting diodes 12R, 12G and 12B for displaying the bit
pictures R2, G2 and B2 will be 2I, the light emission volume of the
light-emitting diodes 12R, 12G and 12B for displaying the bit
pictures R4, G4 and B4 will be 4I and the light emission volume of
the light-emitting diodes 12R, 12G and 12B for displaying the bit
pictures R8, G8 and B8 will be 8I, where I is the light emission
volume for displaying the bit pictures R1, G1 and B1. The light
emission volume ratio of the light-emitting diodes 12R, 12G and 12B
can also be varied depending on the human luminosity and liking of
the user.
[0208] By the above operations, the light beams of the plural bit
pictures, weighted from color to color in each frame, are
sequentially projected on the screen 17. The bit pictures are
perceived as being a color picture by the viewer because of the
after-image effect proper to the human visual system. When
time-divisionally displaying plural monochromatic pictures, bit
pictures with different display colors are sequentially displayed
in such a manner as to evade contiguous display of the bit colors
of the same colors. This shortens the time during which the
monochromatic pictures are displayed contiguously and hence reduces
the occurrence of the color splitting or the edge chromatic
phenomenon.
[0209] By driving the picture display device as shown in FIGS. 26
to 33, color splitting or the edge chromatic phenomenon is hardly
produced to enable display of a satisfactory picture.
[0210] Although 16 gradations are displayed in the above
description, the number of gradations may be larger or smaller than
16 in applying the present invention. That is, 8 gradations may be
displayed with the gradation data per pixel being 3 bits.
Similarly, 256 gradations may be displayed with the gradation data
per pixel being 8 bits, or 1024 gradations may be displayed with
the gradation data per pixel being 16 bits.
* * * * *