Abstract: An improved fire detector unit has a plastic base defining a smoke chamber for detection of a smoke density in terms of light scattering due to the smoke particles in the smoke chamber. The base carries a circuit board mounting a light emitting element, a light receiving element, and other components forming a fire detecting circuit responsible for generating a fire warning signal based upon the detected smoke density. A metal-made electromagnetic shield is molded into the base to protect the light receiving element from electromagnetic radiation noises. The electromagnetic shield includes a ground terminal for connection with a ground line of the circuit board. In addition, terminal pins are molded into the base for electrical and physical connection of the circuit board to the base.

Abstract: A particle sensor has a gain control and an offset voltage adjustment so as to provide a consistent sensor output indicative of the particle density in match with a predetermined relationship between the sensor output and the particle density, while compensating for background noises. The gain control and the offset voltage adjustment are realized respectively by digitally controllable variable resistor networks each having a plurality of switches. A memory module is included in the sensor to store instruction data for control of the switches and therefore responsible for the gain control and the offset voltage adjustment. In particular, the particle sensor includes a memory interface which enables the selective use of two types of memory means, one is an intelligent memory module composed of EEPROM and a microcomputer, and the other is a normal memory module consisting of EEPROM.

Abstract: An improved fire alarm system capable of reliably detecting the presence of fire caused by different sources. The fire alarm system detects a smoke density (S) as well as a temperature difference (&Dgr;T) within a predetermined time interval, and has primary criteria of (i) whether the smoke density (S) exceeds a smoke threshold [e.g., S>5%/m]; (ii) whether the temperature difference (&Dgr;T) exceeds a temperature difference threshold [e.g., &Dgr;T≧18 C]; and (iii) whether a combination of S and &Dgr;T satisfies an inequality [e.g. 2S+&Dgr;T≧12] which is based upon a decreasing function of &Dgr;T with an increase of S. The detected smoke density and the temperature difference are examined with reference to the primary criteria so as to provide a fire warning signal indicating a possible fire presence when anyone of the above primary criteria is satisfied.

Abstract: A method of fabricating various models of fire detectors only from a limited number of common parts or unit in accordance with user's specific needs but at a reduced cost. The method utilizes a smoke sensor unit (1), a thermal sensor unit (2), a signal processing unit (3), a signal transmission unit (4), and a power unit (5), and then combines at least one of the smoke sensor unit and the thermal sensor unit with the power unit and optionally with at least one of the signal processing unit and the signal transmission unit.

Abstract: An improved fire alarm system capable of reliably detecting the presence of fire caused by different sources.

Abstract: A method of fabricating various models of fire detectors only from a limited number of common parts or unit in accordance with user's specific needs but at a reduced cost. The method utilizes a smoke sensor until (1), a thermal sensor unit (2), a signal processing unit (3), a signal transmission unit (4), and a power unit (5), and then combines at least one of the smoke sensor unit and the thermal sensor unit with the power unit and optionally with at least one of the signal processing unit and the signal tansmission unit.

Abstract: An improved fire detector unit has a plastic base defining a smoke chamber for detection of a smoke density in terms of light scattering due to the smoke particles in the smoke chamber. The base carries a circuit board mounting a light emitting element, a light receiving element, and other components forming a fire detecting circuit responsible for generating a fire warning signal based upon the detected smoke density. A metal-made electromagnetic shield is molded into the base to protect the light receiving element from electromagnetic radiation noises. The electromagnetic shield includes a ground terminal for connection with a ground line of the circuit board. In addition, terminal pins are molded into the base for electrical and physical connection of the circuit board to the base.

Abstract: A particle sensor has a gain control and an offset voltage adjustment so as to provide a consistent sensor output indicative of the particle density in match with a predetermined relationship between the sensor output and the particle density, while compensating for background noises. The gain control and the offset voltage adjustment are realized respectively by digitally controllable variable resistor networks each having a plurality of switches. A memory module is included in the sensor to store instruction data for control of the switches and therefore responsible for the gain control and the offset voltage adjustment. In particular, the particle sensor includes a memory interface which enables the selective use of two types of memory means, one is an intelligent memory module composed of EEPROM and a microcomputer, and the other is a normal memory module consisting of EEPROM.