Computer graphics processing and selective visual display system – Display peripheral interface input device – Touch panel
Reexamination Certificate
1997-10-22
2001-04-10
Chang, Kent (Department: 2778)
Computer graphics processing and selective visual display system
Display peripheral interface input device
Touch panel
C178S018030, C178S018020
Reexamination Certificate
active
06215477
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to electronic writeboards and in particular to a touch sensitive display panel and an electronic writeboard for a noisy display panel.
BACKGROUND OF THE INVENTION
Electronic writeboards are known in the art and have been used in conjunction with multimedia and communications software to provide enhanced teleconferencing capabilities. Conventional electronic writeboards have typically been of the resistive air gap (RAG) type and include a multi-layer transparent, flexible, touch sensitive panel. The touch sensitive display panel generates control signals in response to pressure applied thereto representing the locations of the applied pressure. A processor receives the control signals and in response generates graphic images which are displayed on the passive display panel to update the displayed images. These electronic writeboards are generally used with the passive display panel either in a stand alone mode or in a projection mode. Since passive display panel make use of passive optical elements, the passive display panels do not emit stray noise signals which impact adversely the operation of RAG type electronic writeboards.
Plasma displays panels have however, begun to replace passive display panels due to the fact that they are brighter than passive projection display panels and provide greater economical offerings. Unfortunately, plasma display panels are noisy and emit a significant level of stray noise signals corresponding to clock signals used to switch the display elements therein. It has been found that when conventional RAG type electronic writeboards are installed in close proximity to plasma display panels, the electronic writeboards pick up these stray noise signals affecting adversely their operation. Accordingly, electronic writeboards suitable for use with noisy display panels are desired.
It is therefore an object of the present invention to provide a novel touch sensitive display panel and an electronic writeboard for a noisy display panel.
SUMMARY OF THE INVENTION
According to one aspect of the present invention there is provided a touch sensitive display panel comprising:
a noisy display panel having a display screen on which images are displayed; and
an electronic writeboard on said noisy display panel and overlying said display screen, said electronic writeboard detecting user input and providing output to alter said images, said electronic writeboard including means to compensate for noise generated by said noisy display panel.
Preferably, the compensation means inhibits the electronic writeboard from processing the user input upon detection of noise from the noisy display panel that is above a predetermined threshold value.
In a preferred embodiment, the electronic writeboard includes a generally transparent, touch sensitive panel overlying the display screen of the noise display panel. The touch sensitive panel generates contact position data signals in response to user input made via contact with the touch sensitive panel. A controller receives the output of the touch sensitive panel and processes the contact position data signals. A noise detector detects noise signals emitted by the noisy display panel and inhibits the controller from processing the contact position data signals when the presence of noise signals generated by the noisy display panel is above the predetermined threshold value. The noise signals are picked up by the touch sensitive panel and are superimposed on the contact position data signals when user input is made.
Also, in a preferred embodiment, the noise detection includes a peak detector generating positive and negative envelopes of the input; a combiner to combine the positive and negative envelopes; and a comparator to compare the combined positive and negative envelopes with the predetermined threshold level and to output an active digital level when the noise level exceeds the predetermined threshold. A high pass filters the input prior to the input being applied to the peak detector. A limiter is interposed between the high pass filter and the peak detector.
Preferably, the controller enables the touch sensitive panel at intervals to allow the touch sensitive panel to generate the contact position data signals in response to the user input and initiates a timer upon enablement of the touch sensitive panel to count a predetermined duration. The controller monitors the output of the noise detector over the predetermined duration to detect the presence of noise signals and reads and processes the contact position data signals when the timer counts the predetermined duration and no noise is detected by the noise detector over the predetermined duration. The controller also monitors the output of the noise detector during reading of the contact position data signals and inhibits processing of the contact position data signals and reinitiates the timer when noise is detected by the noise detector during reading.
According to another aspect of the present invention there is provided a touch sensitive display panel comprising:
a plasma display panel having a display screen on which images are displayed; and
an electronic writeboard including a generally transparent touch sensitive panel overlying said display screen, said touch sensitive panel generating contact position data signals in response to user input made via contact with said touch sensitive panel; a controller receiving the output of said touch sensitive panel and processing said contact position data signals thereby to change images displayed on said display screen; and a noise detector inhibiting said controller from processing said contact position data signals when the presence of noise signals generated by said plasma display panel is above said predetermined threshold value.
According to yet another aspect of the present invention there is provided an electronic writeboard for a noisy display panel comprising:
a generally transparent touch sensitive panel to overlie a display screen of said noisy display panel, said touch sensitive panel generating contact position data signals in response to user input made via contact with said touch sensitive panel;
a controller receiving the output of said touch sensitive panel and processing said contact position data signals thereby to detect the position of contact made with a touch sensitive panel; and
a noise detector for detecting noise signals emitted by said noisy display panel, said noise detector inhibiting said controller from processing said contact position data signals when the presence of noise signals generated by said noisy display panel is above said predetermined threshold value.
According to still yet another aspect of the present invention there is provided a touch sensitive display panel comprising:
a noisy display panel having a display screen on which images are displayed; and
an electronic writeboard on said plasma display panel and overlying said display screen and through which said images are visible, said electronic writeboard including a controller detecting user input and providing output to alter said images and a noise detector sensing noise emitted by said noisy display panel, said controller inhibiting processing of said user input when noise is detected by said noise detector.
According to still yet another aspect of the present invention there is provided a touch sensitive panel comprising:
a noisy display panel having a display screen on which images are displayed; and
an electronic writeboard on said noisy display panel and overlying said display screen and through which said images are visible, said electronic writeboard including a touch sensitive panel overlying said display screen; a controller to read contact position data from said touch sensitive panel generated in response to user input; and timing means to enable said controller to process said contact position data signals when noise generated by said noisy display panel is below a predetermined threshold level.
By synchronizing its data acquisition timing to avoid noise
Morrison Gerald D.
Potvin Lucien N.
Chang Kent
Fitzpatrick ,Cella, Harper & Scinto
Smart Technologies Inc.
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