A pyroelectric infrared sensor and a method of manufacturing a dual pyroelectric element used therein

Claim 2

A pyroelectric infrared sensor comprising:

Claim 3

a package having a light-receiving window; and at least two dual pyroelectric elements arranged in said package, each of said at least two dual pyroelectric elements being provided with a pyroelectric film, first and second light-receiving electrodes formed on a first surface of said pyroelectric film to oppose said light-receiving window, and first and second back electrodes formed on a second surface of said pyroelectric film as a surface opposite to the first surface thereof, said first light-receiving electrode, said first back electrode, and a portion of said common pyroelectric film which is sandwiched between said first light-receiving electrode and said first back electrode constituting a first unit pyroelectric element, said second light-receiving electrode, said second back electrode, and a portion of said common pyroelectric film which is sandwiched between said second light-receiving electrode and said second back electrode constituting a second unit pyroelectric element, and said first and second unit pyroelectric elements being connected in series or parallel with each other so as to have opposite polarities, wherein said first and second light-receiving electrodes and said first and second back electrodes are formed such that an effective light-receiving electrode area of said first unit pyroelectric element opposing a central portion of said light-receiving window is smaller than an effective light-receiving electrode area of said second unit pyroelectric element opposing a peripheral portion of said light-receiving window, thereby compensating for a difference between amounts of secondary infrared rays incident on said first and second unit pyroelectric elements which is caused by a difference between angles of visibility of said first and second unit pyroelectric elements with respect to the light-receiving window.

Claim 4

a package having a light-receiving window; and at least two dual pyroelectric elements arranged in said package, each of said at least two dual pyroelectric elements being provided with a pyroelectric film, first and second light-receiving electrodes formed on a first surface of said pyroelectric film to oppose said light-receiving window, and first and second back electrodes formed on a second surface of said pyroelectric film as a surface opposite to the first surface thereof, said first light-receiving electrode, said first back electrode, and a portion of said common pyroelectric film which is sandwiched between said first light-receiving electrode and said first back electrode constituting a first unit pyroelectric element, said second light-receiving electrode, said second back electrode, and a portion of said common pyroelectric film which is sandwiched between said second light-receiving electrode and said second back electrode constituting a second unit pyroelectric element, and said first and second unit pyroelectric elements being connected in series or parallel with each other so as to have opposite polarities, wherein said first and second light-receiving electrodes and said first and second back electrodes are formed such that an effective light-receiving electrode area of said first unit pyroelectric element opposing a central portion of said light-receiving window is smaller than an effective light-receiving electrode area of said second unit pyroelectric element opposing a peripheral portion of said light-receiving window, thereby compensating for a difference between amounts of secondary infrared rays incident on said first and second unit pyroelectric elements which is caused by a difference between angles of visibility of said first and second unit pyroelectric elements with respect to the light-receiving window.

Claim 5

A sensor according to claim 1, wherein said at least two dual pyroelectric elements use a common pyroelectric film.

Claim 6

A sensor according to claim 1 or 2, wherein said light-receiving window is substantially rectangular.

Claim 7

A sensor according to any of claims 1 to 3, wherein said light-receiving electrodes of said at least two dual pyroelectric elements are substantially aligned along said light-receiving window such that said back electrodes of said dual pyroelectric elements respectively oppose said light-receiving electrodes through said pyroelectric film.

Claim 8

A sensor according to claims 1 to 4, wherein the effective light-receiving electrode area of said first unit pyroelectric element is smaller than the effective light-receiving electrode area of said second unit pyroelectric element within a range of 1 to 15%.

Claim 9

A sensor according to claims 1 to 4, wherein the effective light-receiving electrode area of said first unit pyroelectric element is smaller than the effective light-receiving electrode area of said second unit pyroelectric element within a range of 2 to 8%.