Smoke sensor

A smoke sensor, comprising:

• a light-emitting section;
• a light-receiving section;
• a sensor output processing section;
• and
• an operation processing section,
• wherein the light-emitting section outputs pulsed light intermittently towards a sensing space,
• the light-receiving section is disposed at a position not struck by direct light from the light-emitting section, but struck by light from the light-emitting section, that is diffused and reflected by smoke that flows into the sensing space, the light-receiving section receives light and converts the light into a current,
• the sensor output processing section converts an input current, inputted by the light-receiving section, into an output voltage,
• the operation processing section determines presence or absence of the smoke in the sensing space on a basis of the output voltage,
• when the input current fluctuates, the sensor output processing section transiently changes an instantaneous value of the output voltage in accordance with the fluctuation amount,
• the operation processing section has detection means and determination means,
• the detection means detects, as respective measurement values, an instantaneous value of the output voltage at a first sampling timing and a second sampling timing set to be a transient response period of the output voltage for the input current, and
• the determination means detects the presence or absence of the smoke in the sensing space by comparing a predefined threshold value with a difference value between the two measurement values detected by the detection means.

A smoke sensor, comprising:

• a light-emitting section;
• a light-receiving section;
• a detection processing section;
• and
• a determination processing section,
• wherein the light-emitting section intermittently outputs light into a sensing space,
• the light-receiving section is disposed at a position not struck by direct light from the light-emitting section, but struck by light from the light-emitting section, that is diffused and reflected by smoke that flows into the sensing space,
• the detection processing section obtains a detection value corresponding to a smoke concentration in the sensing space on a basis of light reception intensity at the light-receiving section,
• the determination processing section determines presence or absence of fire on a basis of the detection value,
• the determination processing section has storage means and determination means, the storage means stores a plurality of determination levels, and the determination means compares the detection value with the determination levels,
• the determination levels include a reference level, a fire determination level and a state determination level,
• the reference level corresponds to the detection value in a state where no smoke is in the sensing space, the fire determination level is set higher than the reference level and constitutes a criterion for fire, and the state determination level is set lower than the fire determination level and is calculated using at least one from among the reference level and the fire determination level, and
• the determination means determines that there is a fire if the detection value is equal to or greater than the fire determination level, and determines a predefined operating state in accordance with a magnitude relationship between the detection value and the state determination level, if the detection value is smaller than the fire determination level.