JPH0550329U - Pyroelectric infrared detector - Google Patents

Abstract

(57) [Summary] [Structure] Electrodes 4 and 5 are provided on the pyroelectric element 1 other than the sensing electrode pairs 2 and 3 or the temperature compensating electrode pair, and temperature change or stress is applied to the pyroelectric element 1. It suppresses the sudden discharge of electric charges that sometimes occurs. The electrodes 4 and 5 are electrically connected to each other to cancel the generated charges. Further, the electrodes 4 and 5 are electrically connected to the pyroelectric element output portion or the ground, and the generated charges are continuously released to the outside of the pyroelectric element 1 to obtain the same effect. [Effect] Suppressing sudden discharge of charges on the pyroelectric element 1,
The popcorn noise of the pyroelectric infrared detector caused by it is eliminated.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a pyroelectric infrared detector used for human body detection, flame detection, non-contact temperature detection and the like.

[0002]

[Prior Art]

 In the conventional pyroelectric infrared detector, after the element is polarized, an electrode pair is provided at a necessary portion of the element to serve as a sensing electrode or a compensating electrode. This is shown in FIG. The arrow in the figure indicates the direction of polarization. This pyroelectric element 1 has a pyroelectric function also in the portions other than the electrode pairs 2 and 3, and when temperature change or stress is applied to the element 1, electric charges are also generated in the portions other than the electrodes 2 and 3. A small-scale discharge may suddenly occur on the surface of the device 1 until the charge is not sufficiently released into the air. As a result, side effects such as popcorn noise appear in the detector output, which may impair reliability. As a remedy for this, as shown in FIG. 3, the electrode pair 2 and 3 is provided on the element 1, and then only the electrode portion is polarized so that the electric charge is generated in the element portion other than the electrode pair 2 and 3. There is a way to hold it down. However, in this method, it is necessary to bring the electrodes for polarization into contact only with the element electrode pairs 2 and 3, and even if a slight displacement occurs in these electrodes, sufficient polarization is not performed in many cases. Precision was required. Moreover, since the thin element is sandwiched between the electrodes for polarization, the element is often damaged and the element itself is expensive.

[0003]

[Problems to be solved by the device]

 The problems to be solved are that the conventional pyroelectric infrared detector lacks reliability and that the element in which only the sensing electrode pair or the compensating electrode pair is polarized is expensive.

[0004]

[Means for Solving the Problems]

 The main feature of the present invention is that electrodes are provided on elements other than the sensing electrode pair or the compensating electrode pair.

[0005]

[Action]

 Electrodes other than the sensing electrode pair or the compensating electrode pair are provided to suppress sudden discharge of electric charge generated on the element surface other than the sensing electrode pair or the compensating electrode pair when temperature change or stress is applied to the element. In addition, the charge is smoothly released into the air. In addition, the electrodes are formed on both sides of the element as a pair and electrically connected to each other (hereinafter simply referred to as “connection”) or connected to an arbitrary element output part or the ground to cancel the electric charge generated in the electrode. Or, it is allowed to escape to the outside of the element continuously to eliminate the side effect on the sensing electrode pair or the compensation electrode pair. Alternatively, the same effect can be obtained by attenuating the polarization of only the electrode pair.

[0006]

【Example】

 FIG. 1 shows the most basic embodiment of an element used in a detector according to the present invention. The entire surface of the element 1 is polarized. 1B is a top view of the device shown in FIG. 1A, and FIG. 1C is a bottom view of the device, and electrodes 2 and 3 are a pair of sensing electrodes. When temperature change or stress is applied to the element 1, electric charges are generated on both surfaces of the element due to pyroelectric action, but the electric charges generated in the electrodes 4 and 5 can move within the range of the electrode 4 or 5, so Sudden discharge on the surface is suppressed, and charges are smoothly released into the air. Further, as shown in FIG. 4, when the electrode pairs 4 and 5 are connected to each other by using the conductor 7, the generated charges are canceled and the side effect of the sensing electrode pairs 2 and 3 is prevented. In the embodiment of FIG. 5, the electrode pairs 4 and 5 are connected to the output terminal 6 of the sensing electrode 3. However, the output portion of the element can be connected to any portion, and as shown in FIG. The electrodes 3 and 5 can be shared. According to the embodiment shown in FIG. 6, the output 6 can be taken out from the electrodes 2 and 4 on the same surface of the device 1. If the electrode pairs 4 and 5 are connected to the ground 8 as shown in FIG. 7, the electromagnetic wave shielding effect of the pyroelectric element 1 can be expected, and if one of the output terminals 6 of the element 1 is connected to the ground 8, The electrode pairs 4 and 5 can be connected to the ground 8 by applying the embodiments shown in FIGS. As shown in FIG. 8, the polarization of the electrode pair 4, 5 is attenuated by applying a method such as applying an alternating current or a direct current voltage opposite to the polarization between the electrode pair 4, 5 to attenuate the sensitive electrode pair 2, 3 The pyroelectric function of the other element parts can be suppressed. Further, the reliability of the detector can be further improved by using the embodiments as shown in FIGS. 9 and 10 show examples in which the method according to the present invention is applied to the pyroelectric element of the detector of the single element type with the compensation electrode and the series opposite dual element type, respectively. As shown in FIG. 10, the electrodes 4 and 11 other than the sensing electrode 2 may be divided, and the respective electrode pairs may be connected to the nearby element output terminal 6. When this method is applied to the balanced differential type dual element type detector, the structure of the element 1 becomes symmetric with respect to the center line 12 sandwiched between the two sensing electrodes 2, and the element excellent in thermal balance is obtained. You can Figures 1 and 4 to 8 show pure single element type detectors, and Figures 9 and 10 show the detector element type single element type and series opposite dual element type detector elements. If the electrodes are provided in the element portion other than the electrode pair that does not require the pyroelectric function, the number, shape, size, connection portions, terminals, and the number of the electrodes are arbitrary. Further, the number, shape, and size of the sensing electrode and the compensation electrode are not limited. In the embodiment, the output of the element is taken out using the terminal, but it is not limited to this as long as the output can be taken out. For example, a conductive resin or the like may be used.

[0007]

[Effect of the device]

 As described above, in the pyroelectric infrared detector of the present invention, in the conventional element in which the entire surface is polarized, the sensing electrode pair or the sensing electrode pair that could not be fundamentally eliminated. The side effects on the detector output due to the generation of charges on elements other than the compensating electrode pair are eliminated. Furthermore, it is possible to provide a detector that has the same reliability as an element in which only the electrode part is polarized, which has been expensive in the past, and that uses an inexpensive element, which is industrially valuable. ..

[0008]

[Brief description of drawings]

FIG. 1 is a most basic embodiment of an element used in a pyroelectric infrared detector according to the present invention, in which (a) is a perspective view thereof,
(B) is a plan view of the upper surface and (c) is a plan view of the lower surface.

FIG. 2 is an example of an element used in a conventional detector,
(A) shows a perspective view, (b) shows the sectional view.

3A and 3B show an example of an element in which only the sensing electrodes 2 and 3 are polarized, and FIG. 3A is a perspective view and FIG. 3B is a sectional view thereof.

[Figure 4]

[Figure 5]

[Figure 6]

7A and 7B show an embodiment of an element used in the detector according to the present invention, FIG. 7A is a perspective view, FIG. 7B is a top view, and FIG.

FIG. 8 is an example of a method according to the present invention for attenuating the polarization of electrode pairs 4,5 other than the sensing electrode pairs 2, 3 of the device, (a) is a perspective view showing the method, and (b) is a top view. (C) shows a plan view of the lower surface.

FIG. 9 is an embodiment in which the method according to the present invention is applied to a detector of a single element type with a compensation electrode, (a) is a perspective view of an element part, (b) is an upper surface, and (c) is a lower surface plane. The figure is shown.

FIG. 10 shows an embodiment in which the method according to the present invention is applied to a series opposite dual element type detector,
(A) is a perspective view of an element part, (b) is an upper surface, (c) is a top view of a lower surface.

[0009]

[Explanation of reference numerals in the drawings]

 1. Element 2. Sensing electrode 3. Sensing electrode 4. Electrodes other than the sensing electrode and the compensation electrode 5. Electrodes other than the sensing electrode and the compensation electrode 6. Element output terminal 7. Conductor 8. Grand 9. AC power supply 10. Compensation electrode 11. Common electrode of electrode 5 and electrode 3 or 10 12. Center line of element 1 sandwiching two sensing electrodes 2

Claims (1)

[Scope of utility model registration request] A pyroelectric infrared ray characterized in that an electrode is provided on a pyroelectric element (hereinafter simply referred to as an element) other than a pair of sensing electrodes or a pair of electrodes for temperature compensation (hereinafter referred to as compensation electrode). Detector.