DETECTION DEVICE, SYSTEM, AND METHOD

PROBLEM TO BE SOLVED: To provide a technique for appropriately detecting smoke in a smoke detector mounted on a mobile object such as a vehicle.SOLUTION: A detection device for vehicles, in a smoke detection chamber, causes a light-receiving element to receive scattered light formed when light emitted from a light-emitting element or light applied by the light-emitting element is scattered by smoke particles, and determines presence/absence of the smoke according to a quantity of the received light. The detection device stores a plurality of thresholds for being compared with a signal value output by the light-receiving element, the thresholds including a first threshold and a second threshold corresponding to density of the smoke. The detection device compares the signal value output by the light-receiving element with the first threshold to determine whether or not the smoke has first density or more and, when it is determined to be the first density or more, issues an alert. After determining that the smoke has the first density or more, if a period when the smoke density does not exceed second density continues a prescribed period, the detection device outputs a release signal for releasing the alert.