Translation guide
A device or instrument that detects or senses something. The most common Japanese equivalent is 検出器 (kenshutsuki) for technical/scientific contexts, but the choice depends on what is being detected.
detector (general technical)
metal detector
A device that detects physical quantities, signals, or substances.
General term for a detector in scientific and engineering contexts. Used for detecting light, radiation, gas, etc.
This detector can sense even trace amounts of gas.
Common loanword for 'sensor'. Often used in consumer electronics and everyday tech.
Smartphones are equipped with many sensors.
Often used for detectors that locate or find something, like metal detectors or mine detectors.
I passed through a metal detector at the airport.
Used for devices that sense or perceive, such as fire or smoke detectors. More common in safety equipment.
The fire detector activated.
Common compound words for specific types of detectors.
検出器 (kenshutsuki) is the most general and technical. 探知機 (tanchiki) implies searching/locating (e.g., metal detector). 感知器 (kanchiki) is often used for safety devices that sense environmental changes (fire, gas).
センサー (sensor) is widely understood and used in consumer products. For technical writing, 検出器 is preferred.
Smoke detector.
Please replace the battery in the smoke detector.
Radiation detector.
We measured it with a radiation detector.
Lie detector (polygraph).
Lie detectors are often not admissible as evidence in court.