IPA IP 2024 Question 76
A question IPA Japan published in 令和6年度 ITパスポート試験 公開問題 問76, translated into English. ITPEC is based on the same exams.
Which of the following is the method that is widely used in the touch panels of smartphones and other such devices, and that detects the position of a finger when the finger comes close to the surface of the touch panel?
Explanation
Capacitive — a capacitive touch panel senses the change in electrostatic capacitance that a finger causes as it approaches the surface.
The panel has a grid of transparent electrodes under the glass. The human body conducts electricity, so a finger close to the surface changes the capacitance at the nearest electrodes, and the controller computes the position from where the change is. No pressure is needed, several positions can be detected at the same time (multi-touch), and the glass surface is durable, which is why smartphones and tablets use it. A gloved finger or an ordinary plastic pen does not work, since neither conducts.
Answer (c)
Why not others:
- •(a) — a pressure-sensitive (resistive) panel detects the position where pressing makes two conductive films touch; a finger only approaching it is not detected
- •(b) — an optical panel detects where a finger blocks infrared beams crossing the screen from its frame; it is used mainly on large displays, not widely in smartphones
- •(d) — electromagnetic induction detects a special pen with a coil, as in pen tablets, not a finger
Key rule: Capacitive panels sense a conductive finger near the surface and allow multi-touch; resistive panels need pressure; electromagnetic induction needs a dedicated pen.
Computer Component · AI-written, may contain errors
This question comes from the past questions IPA Japan publishes, translated into English by ITPEC Practice. ITPEC Practice is an independent study tool and is not affiliated with IPA or ITPEC. See the original paper (PDF) or Report an issue.