Pyroelectric sensor

An electronic intrusion detector for sensing the presence of a living object by detecting the infrared energy radiated from said object, said intrusion detector comprising:

• an infrared sensing device including a pyroelectric material substrate and capable of selectively absorbing infrared radiation primarily within a wavelength band corresponding to the wavelength that is given off by a living object and producing an electrical output signal indicating the presence of said radiation;
• said infrared sensing device being mounted at the focal point of a reflective means, said reflective means being arranged to concentrate the energy received from a given viewing area to a concentrated point on the surface of said infrared sensing device;
• said reflective means and sensing device being suitably mounted within an enclosure;
• a single source of battery power mounted within said enclosure;
• electronic circuit means powered by said single source of battery power and arranged to receive the output signal from said infrared sensing means when radiant energy within said band is sensed and produce a first electrical signal indicative thereof;
• said electronic circuit means further includes means for monitoring the energy level of said single source of battery power and produce a second electrical signal when said energy level drops below a predetermined condition;
• and
• alarm means powered by said single source of battery power and arranged to receive said first or second electrical signals and produce a first or second alarm signal, respectively, said first and second alarm signals each being distinctive and capable of identifying which condition exists.

A selective infrared sensing device for detecting radiated energy having a band width of between 5 to 15 microns, said device comprising:

• a. body means formed from a sheet of thin film pyroelectric material;
• b. a plurality of areas of electrically conductive material adhered to one side of said body means, said areas being electrically interconnected in alternating arrangement to form at least two electrode means, each of said electrode means providing an electrical input to a suitable electronic circuit;
• c. a continuous area of electrically conducting material adhered to the opposite side of said body means and substantially covering the side to form a continuous electrode means, said continuous electrode means provides an electrical input to said electronic circuit;
• and
• d. a layer of selective energy absorbing filter material at least partially covering said continuous electrode, said filter material being chosen whereby it does not absorb radiated energy outside of the desired wavelengths band but will absorb and convert to heat that energy which is within the desired band, said heat being quickly conducted directly to the pyroelectric material by the continuous electrode;
• e. whereby the change in temperature of said body means creates a change in the surface charge on said pyroelectric material which in turn changes the output voltage from the electrodes to said electronic circuit.

An electronic intrusion detector for sensing the presence of a living object by detecting infrared energy radiated from said object, said intrusion detector comprising;

• an infrared sensing means including a pyroelectric material substrate, a reflective metallic electrode formed on one side of said substrate, a plurality of metallic electrodes formed on the opposite side, and a layer of transparent material formed over said reflective metallic electrode;
• said layer being transparent to received radiant energy which will be reflected and dissipated by the reflective electrode but capable of selectively absorbing infrared energy within an energy wavelength band generally corresponding to the wavelength which is given off by a living object whereby when the infrared energy within the selected wavelength band is present it will be absorbed by said transparent material and converted to heat energy which is conducted through said reflective metallic electrode into said pyroelectric material so that an output signal indicating the presence of said infrared energy is generated by said sensing means;
• a reflective means having said infrared sensing means mounted at its focal point, said reflective means being arranged to concentrate and focus the energy received from a given viewing area associated with said electronic intrusion detector onto said reflective metallic electrode of said sensing means;
• said reflective means and said infrared sensing means being mounted within a conductive enclosure;
• an electronic circuit means powered by a suitable source of electrical energy and arranged to receive the output signal from said infrared sensing means and generate an appropriate electrical signal;
• and
• an alarm means powered by said source of electrical energy and arranged to receive said electrical signal and produce a distinctive alarm signal when said infrared sensing means receives radiant energy within said predetermined wavelength band.