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: A laser diode 11 irradiates an object 3 with beam light modulated in an appropriate cycle. A position detection element 21 outputs a pair of position signals responsive to the position of a light reception spot and a processing section finds a distance to the object 3 based on the position signals. The processing section comprises a modulation control circuit 34 for irradiating the object 3 with beam light as many times as appropriate for performing distance measurement operation, then stopping the distance measurement operation and generating modulation control output indicating the operation stop, and upon reception of modulation control input indicating the operation start from the outside, again starting the distance measurement operation. Therefore, if the modulation control output of one of the two optical displacement measurement devices is directed to the modulation control input of the other, both the optical displacement measurement devices operate alternately, thus do not interfere with each other.

Abstract: An optical displacement measuring system using a triangulation comprises a light projecting unit for emitting to an object a light beam which is amplitude-modulated by a reference signal having a predetermined period, a light receiving unit for receiving light reflected back from the object and providing a pair of position signals, and a control signal generator for providing first and second control signals in synchronism with the reference signal. The position signals are processed by a switching unit in a time sharing manner according to the first control signal to obtain a first composite signal, in which the position signals occur alternately every integral number of the period of the reference signal.