問78
頻出度★☆☆
電車の定期券などとして利用される非接触型 IC カードに用いられている技術はどれか。
平成22年度 春期 ITパスポート試験 問78
テクノロジ系コンピュータ構成要素 › 入出力デバイス
This question's explanation and your answers so far.
解説
問 78
Incorrectア
IrDA is a data-communication standard for infrared light defined by the Infrared Data Association, and it was used for tasks such as exchanging address books between older mobile phones and notebook PCs. Infrared is light, so the infrared ports of the devices must face each other, and communication fails if anything blocks the path. It cannot support the way a card is held up while still inside a wallet, so it is not the technology behind contactless IC cards.
- イ
正解 The correct answer is イ, RFID. RFID stands for Radio Frequency IDentification, and it is a technology in which a reader/writer uses radio waves to read and write data without contact to an IC tag (IC card) that contains an IC chip and an antenna. Many IC tags have no battery: their antenna picks up the radio waves emitted by the reader/writer and generates power from them (a passive tag), so the card works simply by being held up to the reader. The contactless IC cards used for train commuter passes and electronic money (FeliCa-based cards such as Suica and PASMO) apply this RFID mechanism in the 13.56 MHz band, so merely touching the card to a ticket gate updates the balance and travel-section data in an instant. Incidentally, NFC is the standardized form of this short-range contactless communication extended to devices such as mobile phones, and it is one branch of RFID.
Incorrectウ
A barcode is a printed pattern that expresses numbers and other data as a row of lines of differing widths, and it is read by an optical scanner. It is read-only and cannot write to the card side, so it cannot handle processing such as updating a balance. It is also vulnerable to dirt and creases, and it uses no IC chip at all, so it does not qualify as the technology of contactless IC cards.
Incorrectエ
Wireless LAN (the IEEE 802.11 family) is a communication standard for connecting PCs and smartphones to a network within a range of a few tens of meters. It does use radio waves, but establishing a connection requires authentication and configuration steps and consumes a lot of power, so it is not suited to processing that must finish in the instant a battery-less card is held up. It is not the technology used in commuter-pass IC cards.
ここがポイント
- RFID = a technology that reads and writes IC tags / IC cards contactlessly using radio waves. Most tags are passive, needing no battery and drawing power from the reader/writer's radio waves, and they are widely used for transit IC cards, electronic money, product tags, and entry/exit control. NFC, standardized for short-range use, is also one branch of RFID.
- The key point is being able to tell apart similar communication technologies: IrDA is infrared (light, requiring a direct line of sight), a barcode is read optically and cannot be written to, and wireless LAN is for network connection. When you see keywords such as “just hold it up”, “contactless”, and “IC chip”, choose RFID.
用語