Abstract: A fire alarm system, determining existence or nonexistence of a fire by using an ultrasound wave, comprises a sound wave generator and a sound wave detector to detect sound waves propagated through two propagation paths having different lengths each other. The system comprises a calculation means for calculating a pressure ratio between a first sound pressure, which is a sound pressure of a sound wave propagated through a first propagation path, and a second sound pressure, which is a sound pressure of a sound wave propagated through a second propagation path, and a smoke density estimator. The smoke density estimator calculates a change ratio between the pressure ratio calculated by the calculation means and a predetermined standard pressure ratio, and determines a smoke density from the change ratio based on a predetermined relational expression describing the relation between the change ratio and the smoke density, and determines existence of a fire when the smoke density exceeds a predetermined threshold.

Abstract: An infrared ray detector comprises a prism element, a condenser lens, and an infrared ray receiving unit. The prism element is configured to convert the infrared ray irradiated from a detection area of a viewing field to the infrared ray proceeding toward the condenser lens. The condenser lens is configured to concentrate the infrared ray into the infrared ray receiving unit. The infrared ray receiving unit includes a plurality of the infrared ray detection elements. The infrared ray detection elements are arranged in an alternate fashion so as to output electrical signals of positive polarity and negative polarity. Consequently, the infrared ray detector is configured to detect the infrared ray irradiated from a plurality of the detection area, and is configured to detect the infrared ray on the basis of movement of the human in the detection area.

Abstract: A semiconductor substrate shaped to have a curved surface profile by anodization. Prior to being anodized, the substrate is finished with an anode pattern on its bottom surface so as to be consolidated into a unitary structure in which the anode pattern is precisely reproduced on the substrate. The anodization utilizes an electrolytic solution which etches out an oxidized portion as soon as it is formed as a result of the anodization, to thereby develop a porous layer in a pattern in match with the anode pattern. The anode pattern brings about an in-plane distribution of varying electric field intensity by which the porous layer develops into a shape complementary to a desired surface profile. Upon completion of the anodization, the curves surface is revealed on the surface of the substrate by etching out the porous layer and the anode pattern from the substrate.

Abstract: An infrared detection unit includes a base carrying an infrared sensor element, and a cap configured to be fitted on the base to surround the infrared sensor element. The cap has a top wall with a window in which a semiconductor lens is fitted to collect an infrared radiation onto the infrared sensor element. The semiconductor optical lens is formed from a semiconductor substrate to have a convex lens and a flange which surround said convex lens. An infrared barrier is formed on the semiconductor lens to block the infrared radiation from passing through the boundary between the circumference of the convex lens and the window. Accordingly, the infrared sensor element can receive only the infrared radiation originating from a detection area intended by the convex lens.

Abstract: An infrared detector includes a circuit block carrying an infrared sensor element and electronic components. The circuit block is composed of a dielectric resin layer and a first substrate formed with a circuit pattern and mounting the electronic components. The dielectric resin layer is formed in its top with a recess which defines around its periphery with a shoulder for supporting opposite ends of the infrared sensor. The first substrate is integrated to the lower end of the dielectric resin layer with at least one of the electronic components being molded into the dielectric resin layer to make the circuit block of a unified mold structure.

Abstract: An infrared detection unit includes a base carrying an infrared sensor element, and a cap configured to be fitted on the base to surround the infrared sensor element. The cap has a top wall with a window in which a semiconductor lens is fitted to collect an infrared radiation onto the infrared sensor element. The semiconductor optical lens is formed from a semiconductor substrate to have a convex lens and a flange which surround said convex lens. An infrared barrier is formed on the semiconductor lens to block the infrared radiation from passing through the boundary between the circumference of the convex lens and the window. Accordingly, the infrared sensor element can receive only the infrared radiation originating from a detection area intended by the convex lens.

Abstract: The present invention provides a smoke sensor of sound wave type that excels in responsiveness and has a low probability of false detection. The smoke sensor has a sound wave generating unit that provides an ultrasound wave to a monitoring space, a sound wave receiving unit that receives the ultrasound wave from the sound wave generating unit via the monitoring space, and a signal processing unit that detects an abnormality of the monitoring space by using an output of the sound wave receiving unit. The signal processing unit includes a smoke density estimation unit that estimates a smoke density in the monitoring space on the basis of a difference between the output of the sound wave receiving unit and a standard value, and a smoke density determination unit that determines the abnormality of the monitoring space by comparing the smoke density estimated by the smoke density estimation unit with a predetermined threshold.

Abstract: A semiconductor substrate is shaped to have a curved surface profile by anodization. Prior to being anodized, the substrate is finished with an anode pattern on its bottom surface so as to be consolidated into a unitary structure in which the anode pattern is precisely reproduced on the substrate. The anodization utilizes an electrolytic solution which etches out oxidized portion as soon as it is formed as a result of the anodization, to thereby develop a porous layer in a pattern in match with the anode pattern. The anode pattern brings about an in-plane distribution of varying electric field intensity by which the porous layer develops into a shape complementary to a desired surface profile. Upon completion of the anodization, the curves surface is revealed on the surface of the substrate by etching out the porous layer and the anode pattern from the substrate.

Abstract: A semiconductor substrate is anodized to be shaped into an optical lens. Prior to being anodized, the substrate is finished with an anode pattern on its bottom surface so as to be consolidated into a unitary structure in which the anode pattern is precisely reproduced on the substrate. The anodization utilizes an electrolytic solution which etches out oxidized portion as soon as it is formed as a result of the anodization, to thereby develop a porous layer in a pattern in match with the anode pattern. The anode pattern brings about an in-plane distribution of varying electric field intensity by which the porous layer develops into a shape complementary to a desired lens profile. Upon completion of the anodization, the semiconductor substrate is shaped into the lens by etching out the porous layer and the anode pattern from the substrate.

Abstract: A semiconductor substrate with anode pattern is anodized to be shaped into an optical lens. The anodization utilizes an electrolytic solution which etches out oxidized portion as soon as it is formed as a result of the anodization, to thereby develop a porous layer in a pattern in match with the anode pattern. After being removed of the porous layer, the substrate is treated to smooth out minute projections remaining in the top surface of the substrate, thereby obtaining the lens of good transmissivity.

Abstract: An infrared detector includes a circuit block carrying an infrared sensor element and electronic components. The circuit block is composed of a dielectric resin layer and a first substrate formed with a circuit pattern and mounting the electronic components. The dielectric resin layer is formed in its top with a recess which defines around its periphery with a shoulder for supporting opposite ends of the infrared sensor. The first substrate is integrated to the lower end of the dielectric resin layer with at least one of the electronic components being molded into the dielectric resin layer to make the circuit block of a unified mold structure.

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.