| 摘要 |
PURPOSE:To enable a heat source to be surely detected even when the heat source exists at a close location by adding the outputs of a pair of pyroelectric elements that generate inverted outputs relative to each other and canceling the outputs caused by disturbing light each other. CONSTITUTION:The focal points of the divisions A and B of a multi-divided parabolic mirror 3 are disposed on a pyroelectric element 22 and the focal point of a division C is disposed on a pyroelectric element 21. When a heat source exists near a heat ray sensor 1, the element (for example, 21) wherein he focal point is positioned generates a large output by being irradiated by far infrared rays collected by the multi-divided parabolic mirror 3. However, the far infrared rays irradiated on the element 22 out of focus is little and the output of the element 22 is small. Therefore, the output wherein the outputs of the elements 21 and 22 are added to each other is large and the sensitivity of the sensor 1 in a close position is not reduced. Moreover, when disturbing light is present, since this is uniformly irradiated on the sensor 1, the outputs are canceled by each other by the addition of the elements 21 and 22 which generate complementary outputs and the effect of the disturbing light is removed. |
