Technologies of Touch Screen

Digital Matrix Resistive

Digital matrix technology was used before the analog resistive technologies such as 4-wire and 5-wire appeared、and employed on factory automation, copying machines, Faxes, phones, mobile games, calculators cash dispensers and so on.

It sounds weird. Is "digital" sensing method older than "analog" sensing method?

Exactly, digital matrix is old type of the resistive technology. The top and bottom sheets of the digital matrix have ITO coatings and electrodes forming in stripe, vertical and horizontal directions as indicated in the figure. The top and bottom sheets are facing in the way that the striped ITO coatings bisect at right angles. When pressed, the intersections of the ITO coatings contact, and these contacted points are detected as touched points. Each intersection of the ITO coatings works as an independent switch.

I see, digital matrix can detect touched points only on the intersections of the ITO coatings. Then, I think it has only limited resolution and cannot support writing/drawing input.

Yes, it was used on the applications that did not require writing/drawing. Once analog resistive technologies started to be employed for the applications that require writing/drawing such as PDA, electronic personal organizer, and so on, the market has moved from digital matrix to analog resistive technology. Analog resistive technologies came to be employed even for such applications as factory automation and office automation for which digital matrix was used on before. Today, analog resistive technologies are dominant in resistive technology, and digital matrix resistive technology is seldom seen in market.

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