U.S. patent number 3,843,959 [Application Number 05/372,044] was granted by the patent office on 1974-10-22 for matrix type display driving system.
This patent grant is currently assigned to Fujitsu Limited. Invention is credited to Hiroshi Furuta, Norihiko Nakayama, Kenichi Owaki, Toshinori Urade.
United States Patent |
3,843,959 |
Owaki , et al. |
October 22, 1974 |
MATRIX TYPE DISPLAY DRIVING SYSTEM
Abstract
A driving system for matrix type display apparatus having
picture elements arranged in a matrix form, each picture element
being made up of a plurality of luminous elements of different
brightness levels, in which one frame forming one picture is formed
with a plurality of fields. Combinations of the luminous elements
of adjacent picture elements are altered at every field, and the
respective picture elements are scanned in the same manner as that
of scanning in television, thus providing a display.
Inventors: |
Owaki; Kenichi (Kobe,
JA), Nakayama; Norihiko (Kobe, JA), Urade;
Toshinori (Kobe, JA), Furuta; Hiroshi (Akashi,
JA) |
Assignee: |
Fujitsu Limited (Nakahara-ku,
Kawasaki, JA)
|
Family
ID: |
13209823 |
Appl.
No.: |
05/372,044 |
Filed: |
June 21, 1973 |
Foreign Application Priority Data
|
|
|
|
|
Jun 22, 1972 [JA] |
|
|
47-62766 |
|
Current U.S.
Class: |
348/797;
348/E9.012; 348/803 |
Current CPC
Class: |
H04N
9/12 (20130101) |
Current International
Class: |
H04N
9/12 (20060101); H04n 009/30 () |
Field of
Search: |
;178/5.4EL,7.5D,7.3D,5.4R ;315/169R ;313/18B,18D
;340/146.3MA,166EL,166C,166R ;358/59 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Murray; Richard
Assistant Examiner: Godfrey; R. John
Attorney, Agent or Firm: Staas, Halsey & Gable
Claims
What is claimed is:
1. A display system comprising:
a. display device including a plurality of first and second
radiation elements for emitting first and second kinds of radiation
respectively, said plurality of radiation elements disposed in a
matrix of rows and columns so that said first radiation elements
are separated from each other along said columns and rows;
b. energizing means for providing energizing signals to be applied
to said radiation elements; and
c. control means for applying first the energizing signals to a
first field of picture elements, each comprising at least one first
radiation element and one second radiation element, and thereafter
applying the energizing signals to a second field of different
picture elements, each comprised of said one second radiation
element and another first radiation element.
2. The display system as claimed in claim 1, wherein said first
radiation elements emit a relatively high intensity radiation and
said second radiation elements emit a relatively low intensity
radiation.
3. The display system as claimed in claim 1, wherein said first
radiation elements emit radiation of a first wavelength and said
second radiation elements emit radiation of a second, different
wavelength.
4. The display system as claimed in claim 1, wherein said display
device includes third and fourth radiation elements, said first and
second radiation elements emitting radiation of a first color of a
first and a second intensity level, respectively, said third and
fourth radiation elements emitting radiation of a second, different
color of said first and second intensity levels, respectively.
5. The display system as claimed in claim 4, wherein said control
means includes a color control circuit responsive to an input
information signal for providing first and second color signals
indicative of the first and second colors, respectively; first and
second decoder circuits responsive respectively to the first and
second color signals for each providing outputs indicative of said
first and second intensity levels of its respective color; and
first and second memory means, said first memory means responsive
to said first output of said first decoder circuit and said second
output of said second decoder circuit for storing signals
indicative of intensity level and color for at least a portion of
the picture elements of a first row, said second memory means
responsive to the second output of said first decoder and said
first output of said second decoder for storing the energizing
signals indicative of the color and intensity level for at least a
portion of the picture elements of a second row adjacent to said
first row.
6. The display system as claimed in claim 1, wherein said display
device includes third and forth radiation elements for emitting,
respectively, third and fourth kinds of radiation, said first and
second radiation elements being arranged alternately along a first
column, said third and fourth radiation elements being arranged
alternately along a second column adjacent to said first column,
said control means comprising row control means responsive to a
first field signal for selectively applying the energizing signals
to a first and a second row of said radiation elements comprising a
single row of said picture elements, and responsive to a second
field signal for applying the energizing signal to said second row
of radiation elements and a third row of radiation elements
adjacent to said second row.
7. The display system as claimed in claim 6, wherein said
energizing means is responsive to a video input signal to provide
first, second, third and fourth outputs corresponding to the
information contained by said video signal for energizing,
respectively, said first, second, third and fourth radiation
elements, said control means including first and second switch
means associated, respectively, with said first and second columns
of said display device, said first switch means responsive to first
and second timing signals for applying respectively said first and
second outputs to said first column, said second switch means
responsive to said first and second timing signals for applying
said third and fourth outputs, respectively, to said second
column.
8. The display system as claimed in claim 1, wherein said display
device comprises a plasma display panel including a plurality of X
electrodes and a plurality of Y electrodes disposed to intersect
each other, and a discharge gas disposed therebetween, whereby a
plurality of said radiation emitting elements is formed at the
intersecting points of said X and Y electrodes.
9. The display system as claimed in claim 1, wherein said rows of
radiation elements are disposed at approximately 45.degree. with
respect to said columns of said radiation elements.
10. A method of energizing display apparatus comprised of a
plurality of first and second radiation elements for emitting,
respectively, first and second kinds of radiation, the plurality of
radiation elements disposed in a matrix of rows and columns so that
the first and second radiation elements are separated from each
other along said columns and rows, said method comprising the steps
of:
a. energizing a first field of picture elements, each comprised of
one of the first radiation elements and one of the second radiation
elements, and
b. energizing a second field of different picture elements, each
comprised of the one first element and another of the second
radiation elements.
11. The method as claimed in claim 10, wherein in step (a), the one
first radiation element and the one second radiation element are
disposed respectively upon first and second rows adjacent to each
other, and in step (b), the another second radiation element is
disposed upon a third row adjacent to the second row, whereby said
first and second fields are interlaced with each other.
12. The method as claimed in claim 10, wherein the display
apparatus includes first, second, third and fourth radiation
elements for emitting different kinds of radiation, the first and
second radiation elements arranged alternately in each of the first
and third columns of the display apparatus, the third and fourth
radiation elements disposed alternately in a second column
intermediate to the first and third columns, wherein said step (a)
includes forming the first field of at least one picture element
comprised of the first, second, third and fourth radiation elements
disposed in the first and second columns and rows of the display
apparatus, said step (b) includes the forming of the second field
of a second, different picture element comprised of the first,
second, third and fourth radiation elements disposed in the first
and second columns of the second and third rows of the display
device, and thereafter forming a third field comprised of at least
one third picture element comprising the first, second, third and
fourth radiation elements disposed in the second and third columns
of the first and second rows, and thereafter forming a fourth field
comprised of at least one fourth picture element comprising first,
second, third and fourth radiation elements disposed in the second
and third rows and columns of the display apparatus.
13. The method as claimed in claim 10, wherein the display
apparatus includes third and fourth radiation elements for
emitting, respectively, radiation of a second wavelength of first
and second low intensity levels, the first and second radiation
elements emitting respectively, radiation of a first wavelength of
the first and second intensity levels, wherein said step (a)
includes the forming of picture elements comprised of the first,
second, third and fourth radiation elements with at least one idle
row and column formed therebetween; said step (b) includes the
forming the second field of picture elements of the first, second,
third and fourth radiation elements selected from a row of the
first picture element and the adjacent idle row; and further
including the steps of energizing the radiation elements to form a
third field wherein a third picture element is formed of the first,
second, third and fourth radiation elements selected from a column
of the first picture element and the adjacent idle column; and
energizing the radiation elements selectively to form a fourth
field of fourth picture elements comprised of selected first,
second, third and fourth radiation elements selected in part from
the idle row and column associated with the first picture
element.
14. A color picture display system comprising:
a matrix type display apparatus having arrays of picture elements,
each array composed of a plurality of luminous elements of
different colors and brightness levels; and
means for selectively controlling the energization of each of said
plurality of luminous elements of each picture element to "on" and
"off" states in accordance with color and luminance signals applied
to the picture element, the "on" luminous elements, in combination,
providing a display of color picture information of the picture
element and the picture elements, in combination, providing a
display of a color picture of one frame.
15. A color picture display system according to claim 14, in which
said matrix type display apparatus is a plasma display panel having
first and second sets of electrodes disposed in intersecting
relationship and defining discharge cells at the said intersections
of said electrodes said discharge cells serving as said luminous
elements, each picture element being composed of nine discharge
cells defined by the intersections of three adjacent electrodes of
each of said first and second sets, and
said energizing means comprises means for applying different
electric signals to said electrodes of said first set of each
picture element to cause the discharge cells associated with a
given electrode of said first set to discharge at a frequency
different from said cells associated with the other electrodes of
said first set, thereby to cause the three discharge cells
associated with each electrode of said first set to emit
respectively different colors.
16. A color picture display system according to claim 15, wherein
said first and second sets of electrodes are disposed in inclined
relationship with respect to each other.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a system for driving a display apparatus
having luminous elements arranged in a matrix form, and more
particularly to a scanning system for such an apparatus which
provides for enhanced resolution in an image display.
2. Description of the Prior Art
An existing display apparatus of the type having luminous elements
arranged in a matrix form is such, for example, as a plasma display
panel in which first and second sets of electrodes are arranged to
cross each other in adjacent but spaced relation to each other,
whereby discharge cells formed at the intersecting points of the
electrodes serve as luminous elements. In such a plasma display
panel, in order to obtain a display with half tones, picture
elements are each formed with a plurality of discharge cells and
the brightnesses of the discharge cells making up each picture
element are selected different from each other. For exammple, in
the case of forming one picture element with four discharge cells,
if their brightness levels are selected to be 1, 2, 4 and 8, a
display with 16 tone gradations can be achieved. The arrangement of
these discharge cells is such, for example, as depicted in FIG. 1,
in which discharge cells having a brightness level of 1 are formed
at the intersecting points of electrodes Y11, Y21, . . . Ym1 with
those X11, X21, . . . Xn1; discharge cells having a brightness
level of 2 are formed at the intersecting points of electrodes Y12,
Y22, . . . Ym2 with those X11, X21, . . . Xn1; and discharge cells
having brightness levels of 4 and 8 are formed in a similar manner.
An alternating sustain voltage is always impressed to the
electrodes X and Y, and a write or erase voltage is impressed to
selected ones of the electrodes to display a character, a figure or
the like. The brightness levels of the discharge cells can be set
at 1, 2, 4 and 8 or other desired values as by providing, in front
of the discharge cells, filters of different transmission factors,
selecting the numbers of discharging of the cells within a unit
time to be different from one another or coating phosphor on the
cells and making the coated areas or their luminous efficiency to
be different from one another.
Writing of a display content can be achieved by scanning the
electrodes in a manner similar to that of scanning in television
and, in this case, the interlace system can be employed. Namely,
interlaced scanning of lines of picture elements is effected: for
example, lines of the picture elements A'-1, A'-2, . . . are
scanned in a first field and those B'-1, B'-2, . . . are scanned in
a second field as indicated at the left-hand side of FIG. 1. With
the arrangement of FIG. 1, however, the number of the electrodes Y
necessary for displaying a TV picture by such scanning is 1,024 to
provide 512 scanning lines.
SUMMARY OF THE INVENTION
This invention is to provide a novel driving system for matrix type
display apparatus in which a gradation display or a color gradation
display is achieved and combinations of luminous elements making up
individual picture elements are sequentially changed at every field
to provide a display with high resolution.
The driving system for matrix type display apparatus in which
picture elements are each formed with a plurality of luminous
elements of different brightness levels and/or colors emitted
therefrom and are arranged in a matrix form, is characterized in
that one frame constituting one picture is formed with a plurality
of fields; and some of the luminous elements of adjacent picture
elements are selectively combined into individual picture elements
at every field.
Other objects, features and advantages of this invention will
become apparent from the following description taken in conjunction
with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram, for the comparison of one example of
a conventional driving system for a plasma display panel having
picture elements each formed with four discharge cells and one
example of this invention system for such a plasma display
panel;
FIG. 2 is a circuit diagram of the principal part of one example of
this invention;
FIGS. 3A and B, 4, 5A and 5B, inclusive, are diagrams for
explaining the operation of other examples of this invention;
FIG. 6 is a diagram, for explaining the discharge cell arrangement
for a color gradation display;
FIG. 7 shows a series of impression voltage waveforms in case of a
gradation display by changing the numbers of discharging of
discharge cells within a unit time; FIG. 8 is a diagram, for
explaining erasing and writing operations;
FIG. 9 is a block diagram showing another example of this invention
as being applied to a TV picture display;
FIG. 10 is a diagram, for explaining the electrode arrangement in
another example of this invention; and
FIG. 11 is a diagram, for explaining electrode connections.
DESCRIPTION OF PREFERRED EMBODIMENTS
With reference to FIG. 1, one example of this invention for a
gradation display will be described. With the interlace system in
which one frame consists of two fields, in the first field,
electrodes are sequentially scanned in pairs without leaving any
space for the second field, as indicated by A-1, A-2, . . . at the
right-hand side of FIG. 1; and, in the second field, adjacent ones
of the electrodes scanned in the first field are sequentially
scanned in pairs as indicated by B-1, B-2. Accordingly, in the
first field, write scanning of the picture elements surrounded by
dash-dot-dash lines is effected and, in the second field, write
scanning of the picture elements surrounded by dotted lines is
achieved. If the number of horizontal scanning lines is 512, the
number of the electrodes necessary for such scanning system is 513,
which is about one-half of that required in the conventional
system.
FIG. 2 illustrates the principal part of a circuit for performing
such scanning as described above. A horizontal synchronizing signal
HS is applied to an 8-bit counter 1 and its counted content is
decoded by a decoder 2. A video signal having its brightness level
converted into a 4-bit signal is applied to a shift register 3
which stores therein those signals of one horizontal line period.
In FIG. 2, only the shift register 3 for one picture element is
illustrated. A vertical synchronizing signal is applied to a
flip-flop circuit (not shown) to provide field signals F1 and F2
corresponding to the first and second fields respectively. The
field signals F1 and F2 are supplied to an AND gate group G1
together with the output from the decoder 2 and the AND gate group
G1 is further supplied with timing pulses t1 and t2. Reference
characters G2 and G4 designate OR gate groups, DV.sub.x and
DV.sub.y drivers, G3 an AND gate group, and Q1 and Q2 transistors,
which supply a sustain voltage Vs to the electrodes through a diode
matrix.
For example, in the first field, the field signal F1 is applied to
the AND gate group G1 and when an output 1 of the decoder 2
designating a first scanning line has become 1 and the timing pulse
t1 has also become 1, a voltage is impressed to the electrode Y11
from the driver DV.sub.y. At this time, where the contents of the
shift register 3 is 1, 4 and 8, upon application of the timing
pulse t1 to the AND gate group G1 simultaneously with the
application of a write timing pulse tw to the AND gate group G3, a
voltage is impressed to the electrodes X11 and X12 from the drivers
DV.sub.x to effect writing in the discharge cells at brightness
levels of 1 and 4. Then, when the timing pulse t2 is applied, a
voltage is impressed to the electrode Y12 and if the contents of
the shift register 3 are such as mentioned above, a voltage is
impressed to the electrode X12 to effect writing in the discharge
cells at the brightness level of 8. Thus, each picture element is
at a brightness level of 11.
Next, when an output (2) of the decoder 2 designating a second
scanning field has become 1, voltages are impressed to the
electrodes Y21 and Y22 in accordance with the timing pulses t1 and
t2 in the same manner as described above. At that time, since the
shift register 3 has stored therein the 4-bit video signal for the
next horizontal scanning line period, writing is achieved in
accordance with the stored contents.
In the second field, the field signal F2 is applied to the AND gate
group G1, so that once the output (1) of the decoder 2 has become
1, a voltage is impressed to the electrode Y21 upon application of
the timing pulse t1 and to the electrode Y12 upon application of
the timing pulse t2. Where the output (2) of the decoder 2 is 1, a
voltage is supplied to the electrode Y31 (not shown) upon
application of the timing pulse t1 and to the electrode Y22 upon
application of the timing pulse t2.
Consequently, in the first field, pairs of electrodes Ym1 and Ym2
(m = 1, 2, 3, . . . ) are sequentially scanned as indicated by A-1,
A-2, . . . and, in the second field, pairs of electrodes Ym2 and
Y(m + 1) are sequentially scanned as indicated by B-1, B-2, . . . .
In the case of writing by such scanning, it is a matter of course
to erase a previous state by inserting an erasing pulse before
scanning. When the scanning is stopped, the image at that time is
displayed in a stationary condition. Namely, the plasma display
panel has a memory function, so that if the scanning is stopped
when a required image is being displayed, the image can be
continuously displayed in a stationary condition without providing
any external buffer memory.
In the foregoing example, the picture elements are each formed with
four discharge cells and interlaced scanning of the horizontal
electrodes is carried out, but interlaced scanning of the vertical
electrodes is also possible. Namely, dot interlaced scanning is
effected and FIG. 3 is a diagram for explaining it. FIG. 3A shows
picture elements in the case where one frame consists of four
fields, and FIG. 3B shows the order of scanning of the picture
elements on the transmitting side, numerals in brackets indicating
picture element numbers. A video signal for transmission is
produced by scanning picture elements of such numbers whose tenth
and unit digits are both odd, that is, (11), (13), (15), . . .
(31), (33), . . . , in the first field, those of such numbers whose
tenth and unit digits are even and odd respectively in the second
field, those of such numbers whose tenth and unit digits are odd
and even respectively in the third field, and those of such numbers
whose tenth and unit digits are both even in the fourth field.
Upon reception of such a video signal transmitted, in the first and
second fields, the picture elements are scanned without leaving any
interlaced one as in the foregoing example. Namely, in the first
field, the picture elements (11), (13), (15), . . . (31), (33),
(35), . . . are scanned as shown in the first field in FIG. 3A and,
in the second field, the picture elements (21), (23), (25), . . .
(41), (43), (45), . . . are scanned as depicted in the second field
in FIG. 3A. In the next third and fourth fields, picture elements
are each composed of two pairs of horizontally adjoining discharge
cells of the picture elements in the first and second fields, i.e.
in the third field, picture elements (12), (16), . . . (32), (34),
(36), . . . are scanned and, in the fourth field, those (22), (24),
(26), . . . (42), (44), (46), . . . are scanned. Thus, one frame is
completed.
In the case where the scannning procedures on the transmitting side
cannot be altered as depicted in FIG. 3B, that is, for example, in
an existing television transmission, it is possible to achieve such
scanning as described above by selecting the timing for reading out
the content of the shift register on the receiving side. With such
dot interlaced scanning, it is possible to further enhance
resolution even with less electrodes.
FIG. 4 is a diagram for explaining an embodiment of this invention
applied to a color gradation display. This is the case where each
picture element is composed of red, blue and green discharge cell
R, B, and G having brightness levels 1, 2 and 4 respectively.
Reference characters R1, R2, R4, B1, B2, B4, G1, G2 and G4
designate red, blue and green discharge cells having the brightness
levels corresponding to their respective numerals. In such a plasma
display panel, scanning by the conventional sequential scanning
system requires 1,536 horizontal electrodes for 512 scanning lines
but, in the case of one frame consisting of three fields in
accordance with the present invention, the number of electrodes
required can be reduced down to the same as that of scanning lines
forming one frame. Namely, in the first field, triads of horizontal
electrodes are sequentially scanned; in the second field, triads of
horizontal electrodes excepting the uppermost one are sequentially
scanned; and, in the third field, triads of horizontal electrodes
excepting the two upper ones are sequentially scanned, as clearly
shown in FIG. 4. In this manner, scanning for one frame is
achieved.
By the application of such divisional scanning to the vertical
electrodes, too, one frame is composed of nine fields, which
enables enhancement of resolution with a small number of
electrodes.
In FIGS. 5A and 5B, there is illustrated a modification of the
above-described one-frame-with-nine-fields scanning system, in
which one frame consists of four fields. FIG. 5A shows that, in the
first and second fields, the electrodes are scanned in such a form
that one electrode corresponding to picture elements surrounded by
blocks 101 and 102 is inserted as an idle electrode between
adjacent picture elements surrounded by blocks 100 and 200. FIG. 5B
shows that, in the third and fourth fields, the electrodes are
scanned in such form that one electrode is inserted as an idle
electrode between adjacent picture elements surrounded by blocks
300 and 400 in the same manner as described above. In this example,
the number of the electrodes is two-thirds of that used in the
conventional sequential scanning system and the brightness
equivalent centers of gravity of the respective picture elements
are arranged at regular intervals.
The driving method for the color gray scale display will
hereinbelow be described more in detail with reference to FIG. 6
and others subsequent thereto. FIG. 6 illustrates the construction
of picture elements of a plasma display panel which employs matrix
electrodes in combination with the dot arrangement of FIG. 4. In
FIG. 6, reference characters XA1, XB1, XC1, XA2, . . . and YA1,
YB1, YC1 YA2, . . . designate electrodes; R1, R2 and R4 red
discharge cells having a brightness ratio of, for example, 1:2:4;
and B1, B2, B4, G1, G2 G4 blue and green discharge cells also
having a similar brightness ratio. Each broken-line block
represents one picture element. The colors can be obtained by
coating color emissive phosphors or providing filters, and the
brightness ratio can be obtained by selecting the numbers of times
of radiation of the cells within a unit time different from one
another or providing filters of different transmission factors. The
brightnesses can also be made different from one another by other
means, for example, making the areas, thicknesses or luminous
efficiencies of the phosphors coated different from one another. In
the case of selecting the numbers of times of radiation different
from one another, as depicted in FIG. 7, by applying voltages VA,
VB, VC and VY to the electrodes XA1, XA2, . . . , XB1, XB2, . . . ,
XC1 XC2, . . . and YA1, YB1, YC1, YA2 respectively, the discharge
cells R1, B1 and G1 radiate once within a unit time T, the
discharge cells G2, R2 and B2 radiate twice and the discharge cells
B4, G4 and R4 radiate four times, thus providing the brightness
ratio of 1:2:4. Accordingly, if one picture element is made up of
these nine discharge cells, a color display of eight gradations can
be provided by selective combinations of the discharge cells. Each
discharge cell serves as one dot of one picture element. If the
kinds of colors of the dots is taken as n and if the number of
gradations is taken as m, one picture element is formed with an
assembly of (m + n)'s dots. If the brightness ratio is selected to
be, for example, 1:2:4:8 . . . , the content of one picture element
is the combination of 2.sup.mn kinds. Usually, three kinds of
colors: red R, Green G and blue B, are the most effective and if
the number of dots of the same color is three, eight gradations can
be obtained as described above.
In TV pictures or the like, the number of gradations m is reguired
to be about 5 or 6, in which case, it is sufficient only to
increase the number of dots making up one picture element. However,
only an increase in the number of dots lowers resolution, so that
it is necessary to reduce the pitch of the discharge cells, that
is, the pitch of the electrodes.
FIG. 8 is a diagram, for explaining a write operation in the plasma
display panel of the construction shown in FIG. 6. In FIG. 8,
reference character VXA, VXB and VXC identify voltages for the
impression to the electrodes XA1, XA2, . . . , XB1, XB2, . . . and
XC1, XC2, . . . respectively; VYA, VYB and VYC voltages for the
impression to the electrodes YA1, YA2, . . . YB1, YB2, . . . and
YC1, YC2, . . . respectively; PE an erasing pulse; and PW a write
pulse. The erasing pulse PE is simultaneously applied to all of the
discharge cells of one picture element to effect erasing at one
time, but selective erasing of each discharge cell or every three
discharge cell is also possible. However, this results in
prolongation of the erasing time. Then, by simultaneous impression
of the write pulse PW to the electrodes YA1 and XA1, the discharge
cell R1 is selected. Further, the impression of the write pulse PW
to the electrodes YB1 and XB1 leads to the selection of the
discharge cell R2. Next, the impression of the write pulse PW to
the electrodes YC1, XB1 and XC1 results in the selection of the
electrodes B2 and R4. As a result of this, the discharge cells R1,
R2, R4 and B2 of the picture element radiate in blue-red (purple)
light. The above writing method is a parallel one, but it is also
possible to effect writing in each discharge cell. Further, by
coating a dielectric layer on the electrodes to provide a memory
function as in the plasma display panel, the discharge radiation by
the cells is continued until the next selective erasing is
achieved.
FIG. 9 is a block diagram showing another example of this invention
as being applied to a color television. The output from an
intermediate-frequency amplifier 10 is detected by a detector
circuit 11, a Y signal derived therefrom is amplified by an
amplifier 12 and applied to a matrix circuit 17. A signal amplified
by a carrier chrominance signal band amplifier 13 is demodulated by
a demodulator circuit 15 into I and Q signals. In this case, a
burst signal is separated and amplified by a burst
separator-amplifier 14 to control a subcarrier phase control
oscillator 16, the output from which is applied to the demodulator
circuit 15 to achieve the demodulating operation. The matrix
circuit 17 reproduces red G, green G and blue B signals from the Y,
I and Q signals fed thereto, and the red, green and blue signals R,
G and B are applied to decoders 18A, 18B and 18C respectively to
provide decoded outputs of the brightness levels 1, 2 and 4 for
each color. A shift register 19A is supplied with the outputs (1),
(2) and (4) derived from the decoders 18A, 18B and 18C
respectively; a shift register 19B is supplied with the outputs
(2), (4) and (1) from the decoders 18A, 18B and 18C respectively;
and a shift register 19C is supplied with the outputs (4), (1) and
(2) from the decoders 18A, 18B and 18C respectively, thus storing a
signal corresponding to one scanning line. During the horizontal
blanking period, the contents of the shift registers 19A, 19B and
19C are transferred to hold registers 20A, 20B and 20C
respectively. In accordance with the content of the hold register
20A, writing is effected by a gate signal g.sub.1 in the electrodes
XA1, XB1, XC1, XA2, . . . and, in this case, a write pulse is
impressed by the gate signal g.sub.1 to the electrode YA1. Since
one scanning line corresponds to a triad of the electrodes YA1, YB1
and YC1, information one-third that of one scanning line is written
in parallel. Then, gate signals g.sub.2 and g.sub.3 are
sequentially applied to achieve writing as described above and
writing for one scanning line is completed by effecting the writing
operation three times. Erasing is carried out before such writing
and since the shift registers 19A, 19B and 19C are inoperative
during the horizontal blanking period, it is also possible to
dispense with the hold registers. For storing information of one
scanning line, the capacity of each shift register becomes
inevitably large but the capacity of the shift register can be
reduced by dividing one scanning line into a plurality of segments
and writing the information of each segment immediately after it is
stored in the shift register, that is, by writing the information a
plurality of times for one scanning line. Further, various systems
can be considered for the interlaced scanning and color television
can be realized.
In the example of FIG. 6, dots of higher brightness are arranged in
a vertical direction, so that streaks sometimes become noticeable
in the vertical direction. This can be avoided by disposing the
vertical electrodes XA1, XB1, XC1, XA2, . . . inclined at
45.degree. to the horizontal ones YA1, YB1, YC1, YA2, . . . , as
depicted in FIG. 10. In this case, since the electrodes except one
on the diagonal are divided into two groups, they are
interconnected as shown in FIG. 11 and these connections may be
formed on the panel simultaneously with the formation of the
electrodes or may be formed at projecting portions of the
electrodes from the panel.
In the present example, the electrode lead-out position is shifted
one by one at every three writing operations for red, green and
blue colors, so that the content of each register is shifted to the
right at every writing.
As described above, in this example, a gradation color display can
easily be achieved, so that characters, figures, TV pictures and so
on can be displayed. Further an image display with high resolution
can be achieved by making up one frame with a plurality of fields
and altering the combinations of discharge cells of adjacent
picture elements at every scanning of each field, as described
previously.
Although this invention has been described in connection with the
case where discharge cells are employed as luminous elements, the
invention is applicable to the case where luminous elements such as
luminescent diodes or the like are arranged in a matrix form.
Further, by transmitting the brightness levels as PCM signals in
the form of picture element signal arrangement from the
transmitting side for interlaced or dot interlaced scanning, an
image display on the display apparatus can be achieved with much
ease and a gradation display with high resolution can be produced
by the use of a small number of electrodes. In the case of
conventional transmission signals, the scanning system of each of
the foregoing examples can be practised by selecting the timing for
reading out memories on the receiving side.
With the present invention, as described in the foregoing, in the
case of achieving a gradation display and a color gradation display
by the employment of the scanning system, one frame is formed with
a plurality of fields and some of luminous elements of adjacent
picture elements are selectively combined together and scanned as
one picture element for each field, so that the number of
electrodes used can be reduced. Therefore, the display apparatus
can be made small in size and the picture element pitch can also be
reduced, and hence resolution can be enhanced.
This invention is not limited specifically to the foregoing
examples but may be variously modified and varied within the scope
of the concepts defined in the appended claims.
* * * * *