Computer graphics processing and selective visual display system – Display peripheral interface input device – Touch panel
Reexamination Certificate
1994-08-31
2001-07-10
Chang, Kent (Department: 2673)
Computer graphics processing and selective visual display system
Display peripheral interface input device
Touch panel
C345S173000, C178S018110
Reexamination Certificate
active
06259437
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a display-integrated tablet device, and more particularly to a device in which a display and a tablet capable of carrying out coordinate input are integrated with each other.
A conventional display-integrated tablet device is generally constructed in such a manner as shown In FIG.
11
. More specifically, a conventional display-integrated tablet device generally designated by reference numeral
30
in
FIG. 11
includes a matrix tablet (hereinafter merely referred to as “tablet”)
31
for carrying out display and coordinate detection which comprises a thin film electric luminescence (EL) matrix tablet. The tablet
31
includes X-electrodes x
1
to x
m
arranged in a column direction for carrying out horizontal scanning and Y-electrodes y
1
to y
n
arranged in a row direction for carrying out vertical scanning, so that the X-electrodes and Y-electrodes cooperate with each other to form a matrix.
The X-electrodes x
1
to x
m
each are connected to a X-scanning driver
32
, which functions to apply a scan voltage to the X-electrodes x
1
to x
m
at a predetermined timing according to control by a driver controller
34
. The Y-electrodes y
1
to y
n
are commonly connected to a Y-scan driver
33
, which likewise applies a scan voltage to the Y-electrodes y
1
to y
m
at a predetermined timing according to control by the driver controller
34
.
The display-integrated tablet device
30
also includes a CPU
35
for carrying out image display scan control, as well as carrying out detection operation of an input coordinate indicated through a stylus pen
36
based on a peak detection signal at a predetermined timing as described hereinafter.
The stylus pen
36
includes a distal end or pen point for detection, which is adapted to be abutted against the tablet to carry out coordinate detection according to an electrostatic capacity coupling system. Reference numeral
37
designates an amplifier for amplifying a coordinate detection signal output from the stylus pen
36
and
38
is a peak detection section for carrying out peak detection with respect to the coordinate detection signal fed from the stylus pen
36
through the amplifier
37
, to thereby feed a coordinate position at which a peak of the signal is detected to the CPU
35
.
Now, display operation and coordinate input operation which are carried out by the conventional display-integrated tablet device
30
thus constructed will be described hereinafter with reference to FIGS.
12
(
a
) to
12
(
l
) and FIG.
13
.
FIGS.
12
(
a
) to
12
(
l
) each show a waveform of a timing at which scanning of each of the X-electrodes x
1
to x
m
and Y-electrodes y
1
to y
n
of the tablet
31
is executed by each of the X-scan driver
32
and Y-scan driver
33
. As shown in FIGS.
12
(
a
) to
12
(
l
), supposing that a period during which display for one picture plane is carried out and a period during which a pen input position is detected are defined to be a one-image-plane display period corresponding to one frame or one field period, the period is separated into a display period during which display operation is actually carried out and Y- and X-coordinate detection periods.
During the display period, the Y-scan driver
33
applies a scan voltage to the Y-electrodes y
1
to y
n
turn as shown in FIGS.
12
(
a
) to
12
(
c
), to thereby execute vertical scanning. More specifically, application of the voltage to the Y-electrodes y
1
to y
n
is carried out by one line for every one time depending on a vertical/horizontal synchronous signal. The X-scan driver
32
applies a voltage to the X-electrodes x
1
to x
m
within a scan period of each of the Y-electrodes y
1
to y
n
depending on display data fed thereto from the driver controller
34
as shown in FIGS.
12
(
d
) to
12
(
f
). More specifically. the X-scan driver
32
applies the voltage to the X-electrodes corresponding to display cells in the Y-electrodes (horizontal lines) in turn.
Therefore, during scanning of each of the Y-electrodes, a phosphor of each of picture cells intersecting the X-electrodes having a voltage applied thereto is excited for luminescence due to formation of an electric field by the X-electrodes and Y-electrodes, resulting in display operation being carried out.
FIGS.
12
(
g
) to
12
(
l
) each enlargedly show a scan timing of the X-electrodes x
1
to x
m
while enlarging a scan period of the Y electrodes y
1
and y
2
.
When such a display period terminates, operation for a Y-coordinate detection period takes places. An X-coordinate detection period following the Y-coordinate detection period is defined for detecting coordinate input due to abutment of the stylus pen
36
against the tablet
31
.
First, during the Y-coordinate detection period, only the Y-scan driver
33
applies a detection voltage to the Y-electrodes y
1
to y
n
in turn as shown in FIGS.
12
(
a
) to
12
(
c
). Therefore, when the pen point of the stylus pen
36
is kept abutted against a location on the tablet
31
, electrostatic capacity coupling occurs between the Y-electrode positioned in proximity to the location and the stylus pen
36
, so that a voltage is output in the form of a coordinate detection signal from the stylus pen
36
.
Also, during the X-coordinate detection period, only the X-scan driver
32
applies a detection voltage to the X-electrodes x
1
to x
m
in turn as shown in FIGS.
12
(
d
) to
12
(
f
). Thus, when the pen point of the stylus pen
36
is kept abutted against a location on the tablet
31
, electrostatic capacity coupling occurs between the X-electrode positioned in proximity to the location and the stylus pen
36
, resulting in a voltage being output in the form of a coordinate detection signal from the stylus pen
36
.
FIG. 13
is a graphical representation showing a voltage distribution due to electrostatic capacity coupling, wherein an abscissa axis indicates a location in an X-direction or a Y-direction and an ordinate axis indicates electrostatic capacity. As shown in
FIG. 13
, the electrostatic capacity is distributed in the form of a curved shape with respect to a location on the tablet
31
against which the stylus pen
36
is abutted. Therefore, during a period of scanning of an X-electrode (or Y-electrode) adjacent to a certain Y-electrode (or X-electrode), the stylus pen
36
generates a voltage along the curve shown in FIG.
13
.
In view of the above, supposing that the coordinate detection signal shown in
FIG. 13
is fed from the stylus pen
36
through the amplifier
37
to the peak detection circuit
38
, for example, during scanning of a certain Y-electrode, the peak detection circuit
38
detects a peak position of the coordinate detection signal by means of a comparator or the like employing, for example, a voltage as a reference and feeds a peak position signal to the CPU
35
upon the detection.
Then, the CPU
35
discriminates the Y-electrode being scanned during a period corresponding to a timing at which the peak position signal is fed, resulting in the Y-electrode at the location at which the the stylus pen
36
is abutted against the table
31
or the Y-coordinate being discriminated.
This is likewise applied to Y-coordinate detection. More particularly, during the X-coordinate detection period, a scan voltage is applied to the X-electrodes x
1
to x
m
in turn for detection of an X-coordinate, to thereby obtain such a detection signal as shown in
FIG. 13
, resulting in a peak position signal of the voltage being fed to the CPU
35
.
Thus, detection of a Y-coordinate as an input position is carried out during the Y-coordinate detection period and detection of an X-coordinate as an input position likewise takes place during the X-coordinate detection period, so that inputting of the X-coordinate and Y-coordinate by the stylus pen
36
is carried out.
In the conventional display-integrated tablet device constructed as described above, it is required to carry out both image display and coordinate detection by means of the same tablet, so that the one-image-plane displa
Hiraga Katsuya
Kobori Yoichi
Nagasawa Satoshi
Onodaka Koji
Chang Kent
Futaba Denshi Kogyo K.K.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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