Image-display-device drive method, image display device, and image display system

An image display device comprising:

• an image display unit formed of a plurality of scan electrodes and sustain electrodes and a plurality of data electrodes;
• and
• a driver circuit for driving the image display unit by forming one field using a plurality of subfields,
• wherein
• the driver circuit displays an image on the image display unit by having an image display subfield, a y-coordinate detection subfield, and an x-coordinate detection subfield in one field,
• in the y-coordinate detection subfield, the driver circuit applies a y-coordinate detection voltage of positive voltage to the data electrodes and sequentially applies y-coordinate detection pulses of negative polarity to the scan electrodes, and
• in the x-coordinate detection subfield, the driver circuit applies an x-coordinate detection voltage of negative voltage to the scan electrodes and sequentially applies x-coordinate detection pulses of positive polarity to the data electrodes, and
• when the x-coordinate detection voltage of negative voltage is applied to the scan electrodes in the x-coordinate detection subfield, the driver circuit varies a voltage to the x-coordinate detection voltage with a gentle gradient.

An image display system comprising:

• an image display device including an image display unit formed of a plurality of scan electrodes and sustain electrodes and a plurality of data electrodes;
• an electronic pen;
• a coordinate calculating circuit;
• and
• a drawing circuit,
• wherein
• the image display device displays an image on the image display unit by having an image display subfield, a y-coordinate detection subfield, and an x-coordinate detection subfield in one field,
• in the y-coordinate detection subfield, the image display device applies a y-coordinate detection voltage of positive voltage to the data electrodes and sequentially applies y-coordinate detection pulses of negative polarity to the scan electrodes, and
• in the x-coordinate detection subfield, the image display device applies an x-coordinate detection voltage of negative voltage to the scan electrodes and sequentially applies x-coordinate detection pulses of positive polarity to the data electrodes,
• wherein the electronic pen receives a light emission occurring in the image display unit in the y-coordinate detection subfield and a light emission occurring in the image display unit in the x-coordinate detection subfield, and outputs a light receiving signal,
• wherein, based on the light receiving signal, the coordinate calculating circuit calculates:
• a coordinate indicating a position of a light emission, received by the electronic pen, of the light emission occurring in the image display unit in the y-coordinate detection subfield;
• and
• a coordinate indicating a position of a light emission, received by the electronic pen, of the light emission occurring in the image display unit in the x-coordinate detection subfield,
• wherein the drawing circuit generates a drawing signal for displaying, on the image display unit, an image based on the coordinates calculated by the coordinate calculating circuit, and
• wherein the image display device displays an image based on the drawing signal on the image display unit, and
• wherein, when the x-coordinate detection voltage of negative voltage is applied to the scan electrodes in the x-coordinate detection subfield, the image display device varies a voltage to the x-coordinate detection voltage with a gentle gradient.