TOUCH SCREEN DEVICE AND PLASMA DISPLAY APPARATUS HAVING THE SAME
A touch screen device has a screen main body including parallel transmitting electrodes and parallel receiving electrodes disposed in a grid shape; a transmitter sequentially selecting the transmitting electrodes and applying a drive signal; a receiver sequentially selecting the receiving electrodes, receiving a response signal output from the receiving electrode in response to the drive signal, and outputting detection data at each electrode intersection; a controller obtaining a touch position based on the detection data at each electrode intersection output from the receiver; and a reference signal generator outputting a reference signal for synchronized detection. The transmitter generates the drive signal from the reference signal. The receiver uses the reference signal to perform synchronized detection of a signal based on the response signal from the receiving electrode and generates the detection data.
1 . A touch screen device comprising:
a screen main body comprising a plurality of transmitting electrodes provided parallel to one another and a plurality of receiving electrodes provided parallel to one another, the transmitting electrodes and the receiving electrodes being disposed in a grid shape;
a reference signal generator outputting a reference signal;
a transmitter generating a drive signal from the reference signal, sequentially selecting the transmitting electrodes and applying the drive signal;
a receiver sequentially selecting the receiving electrodes and receiving a response signal output from each of the receiving electrodes in response to the drive signal, the receiver comprising a synchronized detector performing synchronized detection for a signal based on the response signal from the receiving electrode, by using the reference signal, and generating detection data, at each electrode intersection, from a signal output from the synchronized detector; and
a controller obtaining a touch position based on the detection data at each electrode intersection output from the synchronized detector of the receiver.
2 . The touch screen device according to claim 1 , wherein the reference signal comprises a continuous pulse wave.
3 . The touch screen device according to claim 2 , wherein the drive signal comprises an intermittent pulse wave
4 . The touch screen device according to claim 3 , wherein the drive signal has a no-signal section at a time of switching the receiving electrodes.
5 . The touch screen device according to claim 1 , wherein
the receiver comprises a sine wave converter converting the reference signal output from the reference signal generator into a sine wave, and
the synchronized detector performs synchronized detection by using the reference signal converted into the sine wave by the sine wave converter.
6 . The touch screen device according to claim 5 , wherein the sine wave converter comprises a bandpass filter.
7 . The touch screen device according to claim 5 , wherein the synchronized detector comprises a multiplier that multiplies the signal based on the response signal from the receiving electrode and the reference signal converted into the sine wave by the sine wave converter.
8 . The touch screen device according to claim 7 , wherein the synchronized detector comprises a low pass filter that removes a component from an output signal of the multiplier.
9 . The touch screen device according to claim 3 , wherein a length of the response signal output from the receiving electrode is set such that the signal output from the synchronized detector declines after reaching a peak value.
10 . The touch screen device according to claim 9 , wherein the receiver comprises a peak value obtainer obtaining a substantially maximum value of the signal output from the synchronized detector and generates the detection data from a signal output from the peak value obtainer.
11 . The touch screen device according to claim 1 , wherein the screen main body is disposed in front of the plasma display panel.
12 . The touch screen device according to claim 11 , further comprising:
an antenna detecting a radiated noise from the plasma display panel; and
a sustained discharge detector detecting a sustained discharge period of the plasma display panel based on an output signal from the antenna.
13 . The touch screen device according to claim 12 , wherein the controller obtains a touch position based on detection data at each electrode intersection obtained during a period other than the sustained discharge period from a detection result of the sustained discharge detector.
14 . The touch screen device according to claim 13 , wherein the controller discards detection data obtained during the sustained discharge period.
15 . The touch screen device according to claim 3 , the receiver comprising a sampler/holder that samples a signal output from a low pass filter proximate a peak value of the output signal.
16 . The touch screen device according to claim 12 , wherein the receiving electrodes comprise the antenna.
17 . The touch screen device according to claim 12 , wherein the antenna comprises a looped conductive wire mounted on a board.
18 . The touch screen device according to claim 12 , the antenna having a resonant frequency proximate an operating frequency of a plasma display panel associated with the touch screen device.
19 . The touch screen device according to claim 14 , wherein the controller again performs scanning after discarding the detection data obtained during the sustained discharge period.
20 . A plasma display apparatus comprising the touch screen device according to claim 1 provided in front of a plasma display panel.