U.S. patent application number 09/103836 was filed with the patent office on 2001-08-09 for display device.
Invention is credited to MIYAZAKI, KAZUMASA, NITO, KEIICHI, SHIROCHI, YOSHIKI, TAKAHASHI, TAKAO, TORIDUKA, MASAMI.
Application Number | 20010011967 09/103836 |
Document ID | / |
Family ID | 15925756 |
Filed Date | 2001-08-09 |
United States Patent
Application |
20010011967 |
Kind Code |
A1 |
MIYAZAKI, KAZUMASA ; et
al. |
August 9, 2001 |
DISPLAY DEVICE
Abstract
A display device has displaying means for by having a line scan
driving circuit disposed in a horizontal direction of a display
region and a pixel driving circuit (dot scan driving circuit)
disposed in a vertical direction of the display region performing
image display with pixel groups each forming one line in the
vertical direction being scanned in the horizontal direction.
Vertical-horizontal converting means is provided for converting an
image data stream supplied presupposing n pixels in a horizontal
direction and m horizontal lines in a vertical scanning direction
into an image data stream for m pixels in a vertical direction and
n vertical lines in a horizontal scanning direction, and the
vertical-horizontal converted data is supplied to the displaying
means by display controlling circuit means. That is, image data is
supplied to the displaying means as a vertical-horizontal converted
data stream and display operation is executed by vertical pixel
rows being scanned in the horizontal direction, as a result of
which the relatively small line scan driving circuit is disposed
above or below the display region instead of the relatively large
dot scan driving circuit and thus the area required for circuit
mounting above/below the display region is reduced and the size of
the display device in the vertical direction can be effectively
reduced.
Inventors: |
MIYAZAKI, KAZUMASA; (TOKYO,
JP) ; TORIDUKA, MASAMI; (KANAGAWA, JP) ;
SHIROCHI, YOSHIKI; (CHIBA, JP) ; TAKAHASHI,
TAKAO; (TOKYO, JP) ; NITO, KEIICHI; (TOKYO,
JP) |
Correspondence
Address: |
JAY H MAIOLI
COOPER & DUNHAM
1185 AVENUE OF THE AMERICAS
NEW YORK
NY
10036
|
Family ID: |
15925756 |
Appl. No.: |
09/103836 |
Filed: |
June 24, 1998 |
Current U.S.
Class: |
345/7 |
Current CPC
Class: |
G09G 5/399 20130101;
G09G 3/3648 20130101; G02B 27/017 20130101; G09G 3/002 20130101;
G09G 3/3614 20130101; G09G 3/20 20130101; G09G 2310/0235
20130101 |
Class at
Publication: |
345/7 |
International
Class: |
G09G 005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 27, 1997 |
JP |
P09-171578 |
Claims
What is claimed is:
1. A video signal display device comprising: displaying means for
by having a line scan driving circuit disposed in a horizontal
direction of a display region and a pixel driving circuit disposed
in a vertical direction of said display region performing image
display with pixel groups each forming one line in said vertical
direction being scanned in said horizontal direction;
vertical-horizontal converting means for converting an image data
stream supplied presupposing n pixels in a horizontal direction and
m horizontal lines in a vertical scanning direction into an image
data stream for in pixels in a vertical direction and n vertical
lines in a horizontal scanning direction; and display controlling
means for executing image display in said display region of said
displaying means by carrying out predetermined processing on and
supplying to said pixel driving circuit image data outputted from
said vertical-horizontal converting means and supplying a
horizontal direction scanning signal synchronized with said image
data outputted from said vertical-horizontal converting means to
said line scan driving circuit.
2. A display device according to claim 1, wherein said displaying
means is a transmitting color liquid crystal display panel and
there is provided a white back light for display operation of said
transmitting color liquid crystal display panel.
3. A display device according to claim 1, wherein said displaying
means is a reflecting color liquid crystal display panel and there
is provided a white front light for display operation of said
reflecting color liquid crystal display panel.
4. A display device according to claim 1, wherein said
vertical-horizontal converting means converts R, G and B color
image data streams supplied presupposing n pixels in a horizontal
direction and m horizontal lines in a vertical scanning direction
into R, G and B image data streams for m pixels in a vertical
direction and n vertical lines in a horizontal scanning direction
and outputs said R, G and B color image data streams
color-sequentially using time division.
5. A display device according to claim 4, wherein said displaying
means is a transmitting monochrome liquid crystal panel and there
is provided an RGB color back light for display operation of said
transmitting monochrome liquid crystal panel and this RGB color
back light carries out a lighting operation RGB color-sequentially
in correspondence with said RGB image data streams
color-sequentially outputted from said vertical-horizontal
converting means.
6. A display device according to claim 4, wherein said display
device is a reflecting monochrome liquid crystal panel and there is
provided an RGB color front light for display operation of said
reflecting monochrome liquid crystal panel and this RGB color back
light carries out a lighting operation RGB color-sequentially in
correspondence with said RGB image data streams color-sequentially
outputted from said vertical-horizontal converting means.
7. A display device according to claim 1, wherein two units of said
displaying means are disposed left-right symmetrically and said
display controlling means so supplies image data and scanning
signals that said two displaying means display the same image while
mutually inverted in a top-bottom direction and in a left-right
direction.
8. A video image signal displaying method comprising: a displaying
step of providing a line scan driving circuit in a horizontal
direction of a display region and providing a pixel driving circuit
in a vertical direction of said display region so that image
display can be carried out by pixel groups each forming one line in
said vertical direction being scanned in said horizontal direction;
a vertical-horizontal converting step of converting an image data
stream supplied presupposing n pixels in a horizontal direction and
m horizontal lines in a vertical scanning direction into an image
data stream for m pixels in a vertical direction and n vertical
lines in a horizontal scanning direction; and a display controlling
step of executing image display in said display region of said
displaying step by carrying out predetermined processing on and
supplying to said pixel driving circuit image data outputted from
said vertical-horizontal converting step and supplying a horizontal
direction scanning signal synchronized with said image data
outputted from said vertical-horizontal converting step to said
line scan driving circuit.
9. A displaying method according to claim 8, wherein said
displaying step is carried out using a transmitting color liquid
crystal display panel and a white back light for display operation
of said transmitting color liquid crystal display panel.
10. A displaying method according to claim 8, wherein said
displaying step is carried out using a reflecting color liquid
crystal display panel and a white front light for display operation
of said reflecting color liquid crystal display panel.
11. A displaying method according to claim 8, wherein said
vertical-horizontal converting step comprises converting R, G and B
color image data streams supplied presupposing n pixels in a
horizontal direction and m horizontal lines in a vertical scanning
direction into R, G and B image data streams for m pixels in a
vertical direction and n vertical lines in a horizontal scanning
direction and outputting said R, G and B color image data streams
color-sequentially using time division.
12. A displaying method according to claim 11, wherein said
displaying step is carried out using a transmitting monochrome
liquid crystal panel and an RGB color back light for display
operation of said transmitting monochrome liquid crystal panel and
this RGB color back light carries out a lighting operation RGB
color-sequentially in correspondence with said RGB image data
streams color-sequentially outputted in said vertical-horizontal
converting step.
13. A displaying method according to claim 11, wherein said
displaying step is carried out using a reflecting monochrome liquid
crystal panel and an RGB color front light for display operation of
said reflecting monochrome liquid crystal panel and this RGB color
back light carries out a lighting operation RGB color-sequentially
in correspondence with said RGB image data streams
color-sequentially outputted in said vertical-horizontal converting
step.
14. A displaying method according to claim 8, wherein said
displaying step comprises disposing two units of displaying means
according to claim 1 left-right symmetrically and said display
controlling step comprises so supplying image data and scanning
signals that said two displaying means display the same image while
mutually inverted in a top-bottom direction and in a left-right
direction.
Description
DESCRIPTION OF THE RELATED ART
[0001] Head-mounted displays comprising display devices such as
small liquid crystal display panels disposed inside a casing having
the form of a pair of spectacles have been developed, and by
wearing one of these head-mounted displays a user can enjoy virtual
large-screen video. An example of a known optical system of a
head-mounted display is shown in FIG. 1.
[0002] This FIG. 1 schematically shows an optical system from
inside a head-mounted display as seen from the left side (from the
side of the left ear of a user wearing the head-mounted display
like spectacles); the left-right direction in the figure is the
front-rear direction of the head-mounted display, which is
positioned in front of the eyes of the user. The optical system
includes a back light 71 and a liquid crystal panel 80 disposed
horizontally at the top of the head-mounted display. The liquid
crystal panel 80 has a display region 81 and an area occupied by a
display driving circuit 82 for driving this display region 81.
[0003] Light of a video picture displayed by the liquid crystal
panel 80 is reflected by a half mirror 72 onto a concave half
mirror 73, and light reflected and enlarged by this concave half
mirror 73 then passes through the half mirror 72 to the eyes of the
user. A liquid crystal shutter 74 is disposed in front of the
concave half mirror 73, and by switching this liquid crystal
shutter 74 between a transparent state and a blocking state with
respect to light from outside the user can as desired control
between seeing to the outside through the head-mounted display
while still wearing the head-mounted display (that is, seeing the
scene outside together with the displayed picture) or seeing only
the displayed picture.
SUMMARY OF THE INVENTION
[0004] If the display region 81 of the liquid crystal panel 80 has
n.times.m pixels in the horizontal and vertical directions
respectively, a dot scan shift register as a pixel driving circuit
for driving n pixels arrayed in the horizontal direction and a line
scan shift register for sequentially scanning m lines arrayed in
the vertical direction are provided in the display driving circuit
82. FIG. 2B is an enlarged view of a part enclosed by the dashed
circle in FIG. 2A and shows parts of the display region 81 and the
display driving circuit 82.
[0005] If the liquid crystal panel 80 is a color panel then image
data for each of the three colors R, G and B are supplied to it,
and FIG. 2B shows the construction of a part corresponding to for
example R image data in an example wherein as R image data three
data are supplied to dot scan shift registers 82b, 82c and 82d in
parallel. For example three consecutive data are inputted in
parallel for reasons relating to image data transfer speed (dot
clock frequency), shift register transfer speed, liquid crystal
response speed and resolution and so on. Thus this case of three
data parallel input is merely an example, and parallel inputting of
four or more data or serial inputting with a single dot scan shift
register are also conceivable.
[0006] These dot scan shift registers (82b, 82c, 82d) are provided
for data of each of the colors R, G and B, and consequently the
area of the circuit part occupied by the dot scan shift registers
disposed in the horizontal direction above or below the display
region 81 is relatively large. Although only R pixels are shown in
FIG. 2B as the pixels of the display region 81, G pixels and B
pixels are also similarly arrayed (in substantially the same
positions) and driven by a dot scan shift register for G pixels and
a dot scan shift register for B pixels.
[0007] A line scan shift register 82a is disposed as a driving
circuit for vertical scanning on the left side or the right side of
the display region 81. This line scan shift register 82a is used
commonly for all the pixels of the colors R, G and B. That is, the
line scan shift register 82a executes scanning wherein it
successively activates one line of pixels at a time on the basis of
a scanning signal generated from vertical and horizontal
synchronizing signals, and the signal lines of these lines (pixel
gate lines) are common to all the R, G and B pixels of each
line.
[0008] The display driving circuit 82 thus made up of the dot scan
shift registers 82b through 82d and the line scan shift register
82a necessitates a large area for circuit provision on the dot scan
shift register side, i.e. in the vertical direction of the display
region. That is, although only one single line scan shift register
common to R, G and B is needed, because a dot scan shift register
must be provided for each of the colors R, G and B at least three
are necessary, and in the case of three data parallel inputting
shown in FIG. 2B nine are necessary.
[0009] Here, in the head-mounted display described above,
considering the need to make the display part positioned in front
of the eyes of the user small and light and considering aesthetic
design aspects, it is desirable for the head-mounted display to be
made small in the front-rear direction. To make the head-mounted
display small in the front-rear direction, as can be seen from FIG.
1 it is necessary to reduce the front-rear direction dimensions of
the back light 71 and the liquid crystal panel 80, which are
disposed horizontally. However, although reducing the size of the
back light 71 is not so difficult, reducing the size of the liquid
crystal panel 80 in the front-rear direction (that is, the vertical
direction of the screen as seen by the user) is difficult.
[0010] This will now be explained with reference to FIG. 2A. As
mentioned above, for the dot scan shift registers to be disposed
above or below the display region 81, the display driving circuit
82 requires a large area for example above the display region 81,
as shown in FIG. 2A. Consequently, even if the size of the display
region 81 is reduced as shown in FIG. 2A to reduce the front-rear
direction size of the liquid crystal panel 80, because the size of
the display driving circuit 82 in the vertical direction does not
change, the front-rear direction size of the liquid crystal panel
80 cannot be effectively reduced.
[0011] Although it is conceivable to dispose the dot scan shift
registers in a position on the left or on the right of the display
region 81, because in this case the laying of signal lines to the
many pixels lined up in the horizontal direction becomes extremely
complicated and in the end also necessitates area in the vertical
direction, it is not suitable means for solving the problem.
[0012] Thus because of the difficulty of reducing the size of the
liquid crystal panel 80 in the vertical direction there has been
the problem that it is not possible to realize size reduction of a
head-mounted display in the front-rear direction.
[0013] It is therefore an object of the present invention to
provide a display device with which it is possible to effectively
realize size reduction in the vertical direction.
[0014] To achieve this and other objects, according to a first
provision of the invention a display device comprises displaying
means for, by having a line scan driving circuit disposed with
respect to pixel rows of a horizontal direction of a display region
and a pixel driving circuit (dot scan driving circuit) disposed
with respect to pixel rows of a vertical direction of the display
region, performing image display with pixel groups each forming one
line in the vertical direction being scanned in the horizontal
direction, vertical-horizontal converting means for converting an
image data stream supplied presupposing n pixels in a horizontal
direction and m horizontal lines in a vertical scanning direction
into an image data stream for m pixels in a vertical direction and
n vertical lines in a horizontal scanning direction, and display
controlling circuit means for executing image display in the
display region of the displaying means by carrying out
predetermined processing on and supplying to the pixel driving
circuit of the displaying means image data outputted from the
vertical-horizontal converting means and supplying a horizontal
direction scanning signal synchronized with that image data to the
line scan driving circuit. That is, image data is supplied to the
displaying means as vertical-horizontal converted data streams and
a display operation is executed by vertical pixel rows being
scanned in the horizontal direction. In this case, because the line
scan driving circuit is disposed above or below the display region,
the area required for circuit provision above or below the display
region is reduced.
[0015] In a second provision of the invention, the
vertical-horizontal converting means converts RGB color image data
streams supplied presupposing n pixels in a horizontal direction
and m horizontal lines in a vertical scanning direction into RGB
image data streams for m pixels in a vertical direction and n
vertical lines in a horizontal scanning direction and outputs these
RGB image data streams color-sequentially using time division.
Also, the displaying means is a transmitting or reflecting
monochrome liquid crystal display panel, and for display operation
of this monochrome liquid crystal display panel an RGB color back
light or an RGB color front light carries out a light-emitting
operation RGB color-sequentially in correspondence with the RGB
image data streams color-sequentially outputted from the
vertical-horizontal converting means. In this case, color display
is possible with displaying means having 1/3 the number of pixels
of an RGB color liquid crystal panel. Or, put another way, in a
liquid crystal panel of the same size, the number of pixels can
effectively be tripled and high resolution thereby achieved.
[0016] According to another provision of the invention, by two
units of the displaying means being disposed left-right
symmetrically and the display controlling means supplying image
data and scanning signals to these two displaying means so that
they display the same image while mutually inverted in a top-bottom
direction and in a left-right direction, it is possible to raise
the freedom of configuration design of for example a head-mounted
display or the like.
[0017] With the first provision of the invention described above,
because a data stream obtained by vertical-horizontal converting
ordinary image data by means of vertical-horizontal converting
means is supplied to the displaying means and the display operation
is executed by vertical pixel rows being scanned in the horizontal
direction, it becomes natural for the line scan driving circuit to
be disposed above or below the display region in the displaying
means. In other words, it becomes unnecessary for a pixel driving
circuit requiring a large area for circuit provision to be disposed
above or below the display region, and as a result there is the
effect that it becomes possible to effectively reduce the size of
the displaying means in the vertical direction. And when the
display device is to be mounted in a head-mounted display, this
makes it possible to reduce the size of the head-mounted display in
the front-rear direction.
[0018] Color display can be realized according to this provision of
the invention by the displaying means being made a transmitting or
reflecting color liquid crystal display panel and there being
provided a white back light or a white front light for display
operation of this color liquid crystal display panel.
[0019] In the second provision of the invention described above,
vertical-horizontal converting means converts RGB color image data
streams supplied presupposing n pixels in a horizontal direction
and m horizontal lines in a vertical scanning direction into RGB
image data streams for m pixels in a vertical direction and n
vertical lines in a horizontal scanning direction and outputs these
RGB image data streams color-sequentially using time division.
Also, the displaying means is a transmitting or reflecting
monochrome liquid crystal display panel, and for display operation
of this monochrome liquid crystal display panel an RGB color back
light or an RGB color front light carries out a lighting operation
RGB color-sequentially in correspondence with the RGB image data
streams color-sequentially outputted from the vertical-horizontal
converting means. In this case, displaying means having the same
resolution as an RGB color liquid crystal display panel can have
1/3 of the pixels, and there is the effect that it is possible to
realize simplification of the circuit construction and accompanying
reduction in size of the displaying means. Or, considering
displaying means the same size (having the same total number of
pixels) as an RGB color liquid crystal display panel, because
effectively the number of pixels is tripled, there is the effect
that high resolution can be achieved.
[0020] When according to the other provision of the invention
mentioned above two units of the displaying means are disposed
left-right symmetrically and the display controlling means supplies
image data and scanning signals to these two displaying means so
that they display the same image while mutually inverted in a
top-bottom direction and in a left-right direction, there is the
effect that it is possible to raise the freedom of configuration
design of for example a head-mounted display or the like.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a view illustrating an optical system of a
head-mounted display;
[0022] FIGS. 2A and 2B are views illustrating a problem relating to
the vertical size of a liquid crystal panel;
[0023] FIG. 3 is a block diagram of a display device of a first
preferred embodiment of the invention;
[0024] FIGS. 4A through 4D are views illustrating a memory
operation of the same display device;
[0025] FIGS. 5A through 5C are views illustrating a
vertical-horizontal converting operation carried out by memories in
the same display device;
[0026] FIGS. 6A and 6B are views illustrating field inversion in
the first preferred embodiment;
[0027] FIGS. 7A and 7B are views illustrating the construction of a
liquid crystal panel in the first preferred embodiment;
[0028] FIGS. 8A through 8C are views illustrating configurations of
display devices according to the first preferred embodiment inside
a head-mounted display;
[0029] FIG. 9 is a block diagram of a display device of a second
preferred embodiment of the invention;
[0030] FIGS. 10A through 10D are views illustrating a triple speed
color-sequential output of the second preferred embodiment;
[0031] FIGS. 11A and 11B are views illustrating field inversion in
the second preferred embodiment;
[0032] FIG. 12 is a view illustrating a liquid crystal panel and a
back light of the second preferred embodiment;
[0033] FIG. 13 is a view illustrating a lighting operation of a
back light of the second preferred embodiment; and
[0034] FIG. 14 is a view illustrating a relationship between a
lighting operation of a back light and scanning timing in the
second preferred embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0035] A first preferred embodiment of a display device according
to the invention will now be described with reference to FIG. 3
through FIG. 8C. FIG. 3 is a block diagram of the display device of
this first preferred embodiment, and for example one display device
having the construction shown in FIG. 3 may be provided for each
eye of a user inside a head-mounted display 30 of the kind shown in
FIGS. 8A through 8C having the form of a pair of spectacles.
[0036] Signals of the three primary colors R, G and B (an R signal,
a G signal and a B signal) are supplied as video signals to this
display device, and these R, G and B signals are each converted
into digital data by an A/D convertor 1.
[0037] As will be further discussed later, the display device of
this preferred embodiment has the feature that a liquid crystal
panel 20 for executing display executes image display of one frame
by pixel groups each forming one line in the vertical direction
being successively scanned in the horizontal direction. That is,
vertical and horizontal are reversed compared to the display
operation of an ordinary display device wherein horizontal lines
are scanned in the vertical direction. Because the R, G and B
signals supplied to the display device are video signals based on
ordinary scanning wherein horizontal lines are scanned in the
vertical direction, if they were to be used as they are then
vertical and horizontal would be displayed inverted on the liquid
crystal panel 20 and correct display would not be possible due to
the differences in the horizontal and vertical numbers of pixels.
For this reason, in this preferred embodiment, switches 2 and 4,
memories 3a and 3b, and a memory controller 9 function as a circuit
part for vertical-horizontal inverting the video signals to adapt
them to the horizontal scanning of the liquid crystal panel 20 of
this preferred embodiment.
[0038] When the switch 2 is switched to terminals ta, the R, G and
B signals outputted from the A/D convertor 1 are severally supplied
as write data to the memory 3a, and when the switch 2 is switched
to terminals tb the R, G and B signals are supplied as write data
to the memory 3b. The stored R, G and B signals are subsequently
read from the memory 3a, and when the switch 4 is switched to
terminals ta the R, G and B signals read out from this memory 3a
are outputted from the switch 4 to a .beta. correction circuit 5.
The R, G and B signals stored in the memory 3b are similarly
outputted from the switch 4 to the .beta. correction circuit 5 when
the switch 4 is switched to terminals tb. The memories 3a, 3b each
have a capacity such that they can store R, G and B signals of at
least one video signal field.
[0039] The switching operation of the switches 2, 4 and the
writing/reading operation of the memories 3a, 3b are controlled by
the memory controller 9. The memory controller 9 generates
switching timing for the switches 2, 4 and writing/reading
operation timing for the memories 3a, 3b from a horizontal
synchronizing signal HD and a vertical synchronizing signal VD and
controls the various parts accordingly.
[0040] Specifically, the timing of the switching operation of the
switches 2, 4 and the writing/reading operation of the memories 3a,
3b implemented by the control of the memory controller 9 is as
shown in FIGS. 4A through 4D. That is, the control of the memory
controller 9 switches the operations every one field period (shown
by `V`) and executes writing and reading of one field unit to and
from the memories 3a, 3b alternately.
[0041] First, in a certain field period the switch 2 is switched to
the terminals ta and writing to the memory 3a is executed. Thus R,
G and B signals of that field period are written to the memory 3a.
At this time, R, G and B signals of the immediately preceding field
period have been written to the memory 3b. Therefore, when writing
to the memory 3a starts, data of the immediately preceding field is
stored in the memory 3b. Accordingly, simultaneously with the start
of the writing of data of a certain field to the memory 3a, the
memory controller 9 starts the reading of data of the immediately
preceding field from the memory 3b. Also, simultaneously with this
the memory controller 9 switches the switch 4 to the terminals tb
and thereby supplies the data read out from the memory 3b to the
next circuit part. In the next field period, reversely, the memory
controller 9 switches the switch 2 to the terminals tb and commands
writing to the memory 3b. Thus data of that field period is written
to the memory 3b. At the same time, the memory controller 9
commands reading from the memory 3a and switches the switch 4 to
the terminals ta and thereby supplies the data of the immediately
preceding field as of that time to the next circuit part.
[0042] By writing/reading being carried out alternately by the
memories 3a, 3b in this way, the data of all fields is supplied to
the circuit parts from the .beta. correction circuit 5 onward
delayed by one field period; however, by the writing order and the
reading order in which the image data of each field is written to
and read from the memories 3a, 3b being made different, the data
stream constituting the image data of each field is
vertical-horizontal inverted. This operation will be explained in
FIG. 5.
[0043] Now, it will be assumed that each of R, G and B signals
constituting video data of one field period outputted from the A/D
convertor 1 is made up of the numbers of pixels shown in FIG. 5C.
That is, n pixels in the horizontal direction and m pixels in the
vertical direction. Seen as a data stream inputted into one of the
memories 3a, 3b, the pixel data is written into the memory 3a or 3b
in the order (0, 0) (0, 1), (0, 2) . . . (0, n) (1, 0) (1, 1) . . .
(1, n) (2, 0) (2, 1) . . . (2, n) . . . (m, 0) (m, 1) . . . (m, n)
in accordance with ordinary display scanning wherein horizontal
lines are scanned in the vertical direction. In correspondence with
this the memories 3a, 3b each have an address space of size
n.times.m corresponding to one field of image data, as shown in
FIG. 5A, and for each supplied data stream of one field in size the
writing of the data is carried out as shown by the arrows in an
address direction corresponding to ordinary display scanning
wherein horizontal lines are scanned in the vertical direction. In
this way the image data of one field is held unchanged in the
memory 3a or 3b.
[0044] At the time of the operation of reading from the memories
3a, 3b, on the other hand, the data reading is carried out in an
address direction corresponding to display scanning which is the
reverse of usual and in which vertical lines are scanned in the
horizontal direction, as shown by arrows in FIG. 5B. As a result,
the image data of one field is read from the memory 3a or 3b in the
order (0, 0) (1, 0) . . . (m, 0) (0, 1) (1, 1) . . . (m, 1) (0, 2)
(1, 2) . . . (m, 2) . . . (0, n) (1, n) . . . (m, n), that is, as a
data stream which has been vertical-horizontal inverted. In other
words, as the memory controller 9 executes writing/reading with
respect to the memories 3a, 3b with the timing shown in FIGS. 4A
through 4D, it realizes a vertical-horizontal conversion of the
image data by making the writing addresses and the reading
addresses it supplies have orders which differ as shown by the
arrows in FIGS. 5A and 5B.
[0045] These R, G and B signals constituting vertical-horizontal
converted image data first undergo .beta. correction processing in
the .beta. correction circuit 5 according to the V-T characteristic
of the liquid crystal panel 20. The .beta.-corrected R, G and B
signals are then severally converted back into analog signals in a
D/A convertor 6.
[0046] The R, G and B signals outputted from the D/A convertor 6
are converted in a field inverting circuit 7 into video signals
having had their polarity inverted every one field (IV). FIG. 6A
shows the R, G and B signals outputted from the D/A convertor 6
with solid lines, broken lines and dotted lines respectively, and
for example video signals like these are outputted with their
polarity inverted every one field as shown in FIG. 6B. The timing
of each field is provided by a liquid crystal panel driving circuit
part 10. The liquid crystal panel driving circuit part 10 generates
timing of one field in accordance with horizontal and vertical
timing from the memory controller 9 and generates a signal for
scanning and supplies this to the liquid crystal panel 20.
[0047] Here, because the R, G and B signals consist of data
vertical-horizontal inverted in the memories 3a, 3b as described
above, although the period length of one field is the same as the
original period length prescribed by the vertical synchronizing
signal VD, for scanning in the liquid crystal panel 20 (i.e.
scanning of vertical lines in the horizontal direction) the
original vertical synchronizing signal VD and horizontal
synchronizing signal HD cannot be used as they are. For this
reason, the liquid crystal panel driving circuit part 10 generates
and supplies to the liquid crystal panel 20 for horizontal
direction scanning a vertical line synchronizing signal whose
timing is based on the reading operation of the memory controller
9.
[0048] The R, G and B signals outputted from the field inverting
circuit 7 are supplied through a buffer 8 to the liquid crystal
panel 20. The liquid crystal panel 20 is a transmitting RGB trio
liquid crystal panel, and has a display region 21 (panel part) and
a display driving circuit 22 for driving pixels in the display
region 21. A white back light 11 is disposed behind the display
region 21 for transmitting display operation.
[0049] The liquid crystal panel 20 is shown in FIGS. 7A and 7B. As
shown in FIG. 7A, in this liquid crystal panel 20 a large-area
region is provided for the display driving circuit 22 on the left
side of the display region (panel part) 21. As this display driving
circuit 22, for example a line scan shift register 22a and dot scan
shift registers 22b, 22c, 22d are disposed as shown in FIG. 7B,
which is an enlarged view of the circled part in FIG. 7A.
[0050] The display region 21 in the transmitting RGB trio liquid
crystal panel 20 has n.times.m pixels in the horizontal and
vertical directions respectively for each of the colors R, G and B,
but by the display driving circuit 22 being made up of dot scan
shift registers 22b, 22c, 22d as a pixel driving circuit for the m
pixels of the vertical direction and a line scan shift register 22a
for successively scanning the n lines of the horizontal direction
it is constructed so that scanning of vertical lines in the
horizontal direction is executed. R, G and B image signals are
supplied from the buffer 8, and FIG. 7B shows the construction of a
part corresponding to the R signal in an example wherein as the R
signal three data are supplied to the dot scan shift registers 22b,
22c, 22d in parallel. As mentioned above with reference to FIG. 2B,
the reason for three consecutive data being inputted in parallel
relates to image data transfer speed (dot clock), shift register
transfer speed, liquid crystal response speed and resolution and so
on. Thus this case of three data parallel input is merely an
example, and parallel inputting of four or more data or serial
inputting with a single dot scan shift register are also
conceivable.
[0051] These dot scan shift registers 22b, 22c, 22d are provided
for data of each of the colors R, G and B, and consequently the
area of the circuit part made up of dot scan registers disposed
vertically in the left part of the liquid crystal panel 20 (or
alternatively the right part) becomes relatively large. Also,
although only R pixels are shown in FIG. 7B as the pixels of the
display region 21, G pixels and B pixels are similarly disposed (in
substantially the same positions), and driven by the dot scan shift
registers for G pixels and the dot scan shift registers for B
pixels.
[0052] The line scan shift register 22a is disposed as a driving
circuit for horizontal direction scanning on the upper side or the
lower side of the display region 21. The line scan shift register
22a is used commonly for the pixels of all three of the colors R, G
and B. By the scanning signal generated in the liquid crystal panel
driving circuit part 10 in synchrony with the vertical-horizontal
inverted video signals being supplied to the line scan shift
register 22a, scanning to successively activate gate lines of the
pixels one vertical line at a time is executed. Because the signal
lines (pixel gate lines) of these lines are common to the pixels of
all three of the colors R, G and B in each line, only one line scan
shift register 22a needs to be disposed commonly for R, G and B
above or below the display region 21, and thus a large area for
circuit provision is not needed in the vertical direction.
[0053] The three data parallel R signal supplied from the buffer 8
to the dot scan shift registers 22b, 22c, 22d and the three data
parallel G signal similarly supplied from the buffer 8 to three dot
scan shift registers not shown in the figures and the three data
parallel B signal also similarly supplied from the buffer 8 to
three dot scan shift registers not shown in the figures, and the
horizontal scanning signal supplied to the line scan shift register
22a from the liquid crystal panel driving circuit part 10, are fed
from a board on which the circuitry up to the buffer 8 is mounted
to a board of the display driving circuit 22 constituting the
liquid crystal panel 20 by a lead line pattern formed on a flexible
board 23 of the kind shown in FIG. 7A.
[0054] In the display device of this preferred embodiment, as
described above, video signals vertical-horizontal converted using
the memories 3a, 3b are impressed on the liquid crystal panel 20
and dot scan shift registers 22b, 22c, 22d are disposed in the
vertical direction on the liquid crystal panel 20 and carry out
vertical direction pixel driving on the basis of these video
signals. Also, a line scan shift register 22a is disposed on the
liquid crystal panel 20 in the horizontal direction, and by a
horizontal scanning signal synchronized with the
vertical-horizontal converted video signals being generated and
supplied to this by the liquid crystal panel driving circuit part
10, scanning of vertical lines is executed in the horizontal
direction. As a result, the video picture displayed on the display
region 21 is an image in a normal upright state (that is, a normal
upright image based on the video signals inputted to the display
device), and the display device can for example be employed as a
liquid crystal panel in a head-mounted display of the kind
described above with reference to FIG. 1 with no problems
whatsoever.
[0055] In the case of this preferred embodiment, because the only
circuit part needing to be parallel with the horizontal direction
is the line scan shift register 22a, it becomes possible for the
vertical direction size of the liquid crystal panel 20 to be
effectively reduced. Since the vertical direction of the liquid
crystal panel 20 corresponds to the front-rear direction of the
head-mounted display 30 of FIGS. 8A through 8C, this is helpful in
reducing the front-rear direction size of a head-mounted display
30. FIGS. 8A, 8B and 8C show examples of head-mounted displays
wherein two display devices according to this preferred embodiment
are disposed to serve the left and right eyes of a user. For
example FIG. 8B shows an example wherein two liquid crystal panels
20, 20 are disposed inside a head-mounted display 30 both oriented
in the same direction. In this case, the orientations of the
pictures displayed on the liquid crystal panels 20, 20 are the same
and constitute no problem. Although not illustrated in the
drawings, both of the liquid crystal panels 20, 20 may
alternatively be disposed so that their flexible boards 23 are on
the left side in the figure.
[0056] However, due to various design restrictions such as
restrictions of the space in which the liquid crystal panels 20 are
to be disposed and spatial conditions for the flexible boards 23
and laying of signal lines, there are cases in which the kind of
configuration shown in FIG. 8B cannot be employed. At such times,
one of the liquid crystal panels may be disposed rotated through
180.degree., as shown in FIGS. 8A and 8C. In this case, because
otherwise the pictures displayed on the liquid crystal panels 20,
20 would be seen by the user as mutually inverted in the top-bottom
direction and in the left-right direction, it is necessary for the
display driving direction of one of the liquid crystal panels to be
inverted in the top-bottom direction and in the left-right
direction. This can be done by, for one of the liquid crystal
panels, reversing the shift directions of the dot scan shift
registers and the line scan shift register or, when
vertical-horizontal inverting the image data, controlling the read
order of the memories 3a, 3b so that top-bottom and left-right
inversion are also carried out. By carrying out this kind of
processing it is possible to execute display with the orientations
of the liquid crystal panels matched even in the cases of the
configurations shown in FIGS. 8A and 8C.
[0057] A head-mounted display does not necessarily need to have two
display devices, one for each eye, and for example a head-mounted
display having just one display device according to the preferred
embodiment is also conceivable.
[0058] Also, although in this preferred embodiment the liquid
crystal panel 20 was made a transmitting RGB trio liquid crystal
panel, a construction using a reflecting RGB trio liquid crystal
panel is also conceivable. In this case, instead of the white back
light 11 disposed behind the liquid crystal panel 20, a white front
light disposed in front of the liquid crystal panel 20 would be
provided. The construction of the rest of the circuitry and the
operation of the display device would be the same.
[0059] A display device of a second preferred embodiment of the
invention will now be described with reference to FIG. 9 through
FIG. 14. Whereas in the first preferred embodiment a transmitting
(or reflecting) RGB trio liquid crystal panel was used as the
liquid crystal panel 20 and a white back light (or a white front
light) was used, this second preferred embodiment is an example
wherein a transmitting (or reflecting) monochrome liquid crystal
panel 60 and an RGB color back light (or an RGB color front light)
are used.
[0060] FIG. 9 is a block diagram of the display device of this
preferred embodiment. Signals of the three primary colors R, G and
B (an R signal, a G signal and a B signal) are supplied to this
device as video signals, and these R, G and B signals are each
converted into digital data by an A/D convertor 41. In this
preferred embodiment also, the liquid crystal panel 60 (a
transmitting monochrome liquid crystal panel) for executing display
executes image display of one frame by pixel groups each forming
one line in the vertical direction being successively scanned in
the horizontal direction. To this end, switches 42, 44, memories
43a, 43b and a memory controller 49 function as a circuit part for
vertical-horizontal inverting the video signals to adapt them to
the horizontal scanning of the liquid crystal panel 60 of this
preferred embodiment.
[0061] Since to effect this vertical-horizontal conversion the
memories 43a, 43b are alternately written to and read from in one
field units in the same way as that described in the first
preferred embodiment, and specifically the memory controller 49
controls the switches and memories with the timing shown in FIGS.
4A through 4D, these processes will not be described again here.
However, in this preferred embodiment, to carry out color display
using the transmitting monochrome liquid crystal panel 60 and an
RGB color back light 51, the vertical-horizontal inverted video
signals (an R signal, a G signal and a B signal) are
color-sequentially outputted at triple speed. This point will now
be explained with reference to FIGS. 10A through 10D.
[0062] FIGS. 10A, 10B and 10C show R, G and B signals outputted
from the convertor 41 to be inputted into one of the memories 43a,
43b. As described above in detail with reference to FIGS. 4A
through 4D, image data written in a certain field period is read
out and supplied to circuit parts from a .beta. correction circuit
45 onward in the next field period; however, in this preferred
embodiment, the R, G and B signals shown in the field period on the
left side in FIGS. 10A, 10B and 10C (written in one of the memories
43a, 43b) are read out as shown in FIG. 10D. That is, in the first
1/3 period of the field one field of R signal is read at triple
speed, in the following 1/3 period of the field one field of G
signal is read at triple speed, and in the final 1/3 period of the
field one field of B signal is read at triple speed. This 1/3
period triple speed reading is carried out in the address direction
illustrated in FIG. 5B, and consequently the triple speed
color-sequential signal of FIG. 10D is a vertical-horizontal
converted signal.
[0063] To output this triple speed color-sequential signal, in
addition to control of the kind described above with reference to
FIG. 4 and FIG. 5, the memory controller 49 carries out control to
sequentially read out the R, G and B signals at triple speed with a
timing of 1/3 of the period of one field. The R, G and B signals
are severally read out to three terminals ta and three terminals tb
of the switch 44, and the memory controller 49 carries out control
to switch between the terminals ta and the terminals tb every one
field and also switch a switch 44a between an R terminal, a G
terminal and a B terminal every 1/3 field. Timing for this triple
speed color-sequential signal readout is generated from a vertical
synchronizing signal VD and a horizontal synchronizing signal HD
and supplied to the memory controller 49 by a video signal time
compression control part 53.
[0064] The R, G and B signals thus vertical-horizontal converted
and made into a triple speed color-sequential signal undergo .beta.
correction processing in the .beta. correction circuit 45 according
to the V-T characteristic of the liquid crystal panel 60. The
.beta.-corrected triple speed color-sequential signal is then
converted back into an analog signal by a D/A convertor 46.
[0065] The triple speed color-sequential signal outputted from the
D/A convertor 46 is converted in a field inverting circuit 47 into
a video signal having had its polarity inverted every 1/3 field
period. FIG. 11A shows R, G and B signals having been made into a
triple speed color-sequential signal outputted from the D/A
convertor 6, and for example this triple speed color-sequential
signal is outputted with its polarity inverted every 1/3 field,
i.e. every one field of individual R, G or B data as shown in FIG.
11B. Timing of every 1/3 field is provided by a liquid crystal
panel driving circuit part 50. The liquid crystal panel driving
circuit part 50 generates this timing of every 1/3 field for
polarity inversion in accordance with timing from the memory
controller 49 synchronized with the triple speed color-sequential
signal and also generates and supplies to the liquid crystal panel
60 a signal for horizontal scanning.
[0066] The triple speed color-sequential signal outputted from the
field inverting circuit 47 is supplied through a buffer 48 to the
liquid crystal panel 60. The liquid crystal panel 60 is a
transmitting monochrome liquid crystal panel, and has a display
region 61 (panel part) and a display driving circuit 62 for driving
pixels in the display region 61. Also, an RGB color back light 51
is disposed behind the display region 61 for transmitting display
operation.
[0067] If the liquid crystal panel 60 is made to have the same
number of video pixels as the liquid crystal panel 20 of FIG. 3,
which is a color liquid crystal panel, because it is a monochrome
liquid crystal panel, it will have 1/3 as many actual pixels. Such
a reduction in the number of pixels with no loss of picture quality
can be used to contribute to a reduction in the size of the liquid
crystal panel 60. Or, seen another way, if the liquid crystal panel
60 is given the same actual pixel makeup as the liquid crystal
panel 20, a tripling of resolution is possible.
[0068] As the scanning for image display in this preferred
embodiment, scanning of vertical lines in the horizontal direction
is carried out in the same way as in the first preferred
embodiment. To this end, as in the construction described above
with reference to FIGS. 7A and 7B, as the display driving circuit
62 a line scan shift register is disposed above or below the
display region 61 and dot scan shift registers are disposed to the
left or to the right of the display region 61. However, in this
preferred embodiment, a predetermined number (x in the case of x
data parallel input) of dot scan shift registers common to the
signals of all three of the colors R, G and B are provided.
[0069] The display device of this preferred embodiment is the same
as that of the first preferred embodiment in that a video signal
vertical-horizontal converted using the memories 43a, 43b is
impressed on the liquid crystal panel 60 and in this liquid crystal
panel 60 dot scan shift registers are disposed in the vertical
direction and carry out vertical direction pixel driving based on
this video signal and a line scan shift register is disposed in the
horizontal direction and is supplied with a horizontal scanning
signal synchronized with the vertical-horizontal converted video
signal generated by the liquid crystal panel driving circuit part
50 and scanning of vertical lines is thereby executed in the
horizontal direction, and as a result of this the size of the
liquid crystal panel 60 in the vertical direction can be
effectively reduced. Also, because the vertical direction of the
liquid crystal panel 60 corresponds to the front-rear direction of
a head-mounted display 30 of the kind shown in FIGS. 8A through 8C,
this is helpful in reducing the front-rear direction size of the
head-mounted display 30.
[0070] Also, in this second preferred embodiment, a transmitting
monochrome liquid crystal panel 60 is used, color display is
carried out by color-sequential lighting of an RGB color back light
51, and as mentioned above a reduction in the number of pixels of
the display or an increase in resolution can be realized
easily.
[0071] Color display operation using color-sequential lighting will
now be described with reference to FIG. 12 through FIG. 14.
[0072] As shown in FIG. 12, behind the display region 61 of the
liquid crystal panel 60 there is disposed an RGB color back light
51. This RGB color back light 51 for example consists of an array
of many R, G, and B light emitting diodes so that it can output
red, green and blue back light. Also, in this preferred embodiment,
the RGB color back light 51 is divided into a left part 51L, a
middle part 51C and a right part 51R.
[0073] As can be seen from the triple speed color-sequential signal
shown in FIG. 10D, in the liquid crystal panel 60 to which this
triple speed color-sequential signal is supplied from the buffer 48
after undergoing various processing, in the first 1/3 period of
each field, scanning (horizontal scanning of vertical lines)
through one frame with an R signal is carried out, in the next 1/3
period scanning (horizontal scanning of vertical lines) through one
frame with a G signal is carried out, and in the final 1/3 period
scanning (horizontal scanning of vertical lines) through one frame
with a B signal is carried out. In correspondence with this
scanning, with the timing shown in FIG. 13, the left part 51L, the
middle part 51C and the right part 51R of the RGB color back light
51 carry out a lighting operation.
[0074] This lighting operation of the left part 51L, the middle
part 51C and the right part 51R is carried out on the basis of
timing and lighting color command information from a back light
color-sequential drive control part 52. The back light
color-sequential drive control part 52 generates lighting control
timing on the basis of timing synchronized with the triple speed
color-sequential signal from the memory controller 49.
[0075] An example of a lighting operation will now be described
specifically with reference to FIG. 13 and FIG. 14. The periods T1,
T2 and T3 in FIG. 13 are periods during which scanning with an R
signal is carried out in the liquid crystal panel 60, the periods
T4, T5 and T6 are periods during which scanning with a G signal is
carried out, and the periods T7, T8 and T9 are periods during which
scanning with a B signal is carried out. As the operation of the
left part 51L, the middle part 51C and the right part 51R, the low
level is a non-lighting state and in the high level periods `R`
indicates red lighting operation, `G` indicates green lighting
operation and `B` indicates blue lighting operation.
[0076] Looking first at the period T1, this period T1 is a period
during which 1/3 of an R signal scan is carried out. In other
words, this is a period during which scanning proceeds through the
left side 1/3 of the display region 61 facing the left part 51L. In
this period, scanning has not reached the parts facing the middle
part 51C and the right part 51R, and the pixels of the right side
2/3 of the display region 61 still hold B signal data of the
immediately preceding field. This of course is a result of a pixel
transmittivity holding function in the pixels of the liquid crystal
panel. Therefore, in the period T1, the state of the display region
61 is as shown in FIG. 14. In FIG. 14 the region being scanned is
shown with hatching, and as shown in this figure in the period T1
the pixels of the left 1/3 of the display region 61 are being
scanned and the pixels of the right 2/3 hold B signal information.
Accordingly, for this period T1, as shown in FIG. 13, in the left
part 51L lighting operation is stopped and in the middle part 51C
and the right part 51R blue lighting operation is executed.
[0077] Then, in the period T2, as can be seen from FIG. 14, the
pixels of the left 1/3 have changed to R signal information with
which they have just been scanned, the middle 1/3 is in the process
of being scanned, and the pixels of the right 1/3 still hold B
signal information. Accordingly, in this period T2, as shown in
FIG. 13, in the left part 51L red lighting operation is executed,
in the middle part 51C lighting operation is stopped, and in the
right part 51R blue lighting operation is continued.
[0078] And in the period T3, as can be seen from FIG. 14, the
pixels of the left 2/3 have changed to R signal information with
which they have just been scanned and the pixels of the right 1/3
are in the process of being scanned. Accordingly, in this period
T3, as shown in FIG. 13, in the left part 51L and the middle part
51C red lighting operation is executed and in the right part 51R
lighting operation is stopped.
[0079] From the period T4, scanning with a G signal is started. As
shown in FIG. 14, in the period T4 the pixels of the left 1/3 of
the display region 61 are being scanned and the pixels of the right
2/3 still hold R signal information. Accordingly, for this period
T4, as shown in FIG. 13, in the left part 51L lighting operation is
stopped while in the middle part 51C and the right part 51R red
lighting operation is executed.
[0080] In this way the states shown in FIG. 13 and FIG. 14 are
executed in one field period, and by this being repeated in every
field period a color video picture is displayed by scanning in the
liquid crystal panel 60 based on color-sequential lighting of the
RGB color back light 51 and a triple speed color-sequential
signal.
[0081] In this preferred embodiment the lighting region of the RGB
color back light 51 is divided into three and its lighting state is
switched every 1/3 period (for example T1, T2, T3) of a scanning
period constituting 1/3 of one field, but the number of divisions
of the lighting region of the RGB color back light 51 can be set
freely. That is, if the number of divisions of the lighting region
is made `Y` then each scanning period constituting 1/3 of one field
is divided into Y periods and the lighting states of the lighting
regions are switched accordingly.
[0082] Also, although in this preferred embodiment the liquid
crystal panel 60 was made a transmitting monochrome liquid crystal
panel, a construction using a reflecting monochrome liquid crystal
panel is also conceivable; in this case, instead of the RGB color
back light 51, an RGB color front light disposed in front of the
liquid crystal panel 60 is provided. The construction of the rest
of the circuitry and the color-sequential scanning and
color-sequential lighting operations of the display device are the
same.
* * * * *