JPH02263122A - Method for arraying sensing electrode for infrared sensing element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to the alignment force of sensing electrodes of an infrared sensing element.

(Prior Art) As shown in FIGS. 4a, b, and c, which show typical models of sensing electrodes for infrared sensing elements, various methods of arranging sensing electrodes are well known.

However, all of these devices have a serious drawback in that they are not sensitive in the vertical or horizontal direction. Also, Figure 4C
The infrared sensing element shown in Figure 1, which is sensitive in the other direction, cannot perform temperature compensation, resulting in large drifts due to temperature changes, resulting in a serious defect in that it malfunctions.

In other words, in the arrangement of the sensing electrodes shown in Figure 4a, the pyroelectric forces generated by the left and right sensing electrodes, which can be sensed in the horizontal direction but cannot be sensed by objects moving in the vertical direction, have polarities that are different from each other. Since they are different, they cancel each other out and cannot function as an infrared sensing element. In other words, it is said to be a blind spot of the infrared sensing element.

The same is true in the same case, and since the central sensing electrode and the two small electrodes divided into left and right sides have different polarities, no output can be obtained as in the former case. On the other hand, those with multi-directionality had a serious defect in that the output due to temperature drift was large and malfunction occurred.

(Problems to be Solved by the Invention) As mentioned above, conventional infrared sensing elements had serious drawbacks such as being unable to sense objects moving vertically or horizontally, or being unable to perform temperature compensation. .

As a result of thorough research into these drawbacks, the present invention has solved all of them.

(Means for Solving the Problem) As shown in FIG. 1.2.3, in the present invention, for convenience, a plurality of sensing electrodes are arranged on one pyroelectric thin plate 11 (an example of one digit is described, but a plurality of It is also within the scope of the present invention to use two thin plates.

First, Figure 1 shows four electrodes arranged on a single pyroelectric thin plate.

These sensing electrodes El, E2. E3. E4. Figure a-0
Describing the case of series connection as shown in
First, when a moving object passes through the infrared sensing element in the lateral direction of the infrared sensing element, an output of -e→2e→C is generated, assuming that the electromotive force per unit electrode is e.

Next, vertically from below the infrared sensing element to the moving body 12.
If it passes, the output is e→-2e −+ e.

Next, as shown in Figure 2, without arranging sensing electrodes in the center of the pyroelectric thin plate (film) 1, six sensing electrodes were arranged around the periphery, and they were arranged in series or in series as shown in Figure b-o. When the wires are connected in parallel as shown in Figure b-2, the moving object moves from the 0 point on the Y axis to a
, b, c, d, passing through the center point e, and then f+
When g+h and i pass through, the following outputs occur from each of the sensing electrodes E1 to E6.

Table 1 Y-axis (same for ±120 degree eccentric axis direction) In other words, when a moving object moves from the zero point in the Y-axis direction and passes through an infrared sensing element, the total output of those infrared sensing elements is e →-2e→2e-+e is generated. When moved from the direction deviated by 120 degrees from the Y-axis, it is the same as the Y-axis signal. When the movable body moves in the same manner as described above from a direction at an angle of around 60 degrees with respect to the Y axis, the polarity is reversed and -e→2e→-2e-*e is generated.

As described above, according to the present invention, output signals can be obtained when a moving body moves in multiple directions, which could not be detected at all using conventional methods.

On the other hand, as shown in Figure 4C, a conventional type in which two electrodes are arranged concentrically is known as a multidirectional sensing type, but the electrode area of the central sensing electrode and the outer peripheral sensing electrode is are designed to be roughly the same and temperature compensated.

However, in practice, although the area of the electrode at the center and the outer periphery is the same, there is a large difference in heat absorption and emission characteristics between the center and the outer periphery of the electrode, so temperature compensation must be performed with high precision. It is impossible to do so.

In principle, the problem cannot be solved unless these two electrodes are pyroelectric thin plates and placed at thermally equivalent positions. A feature of the present invention is a method of arranging sensing electrodes for an infrared sensing element that has solved these problems.

That is, as shown in FIG. 3, the center part of the pyroelectric plate 11 has different thermodynamic conditions from the electrodes at the outer circumference, so no electrodes are placed there, and the conditions are similar only to the outer circumference. Sensing electrodes E1 to E8 were arranged.

The electrical connections of the respective sensing electrodes are arranged in series as shown in figure CO, or the sensing electrodes are connected in odd numbers El, E3, . E5. E7 and even number E2. E4. E6.
Figure C-1 shows E8 divided into two systems connected in series and then connected in parallel, or two independent gate circuits Gl.
, G2 as shown in Figure C-1.

Various combinations of wiring methods are possible.

For example, a pair of sensing electrodes of different polarities or a pair of two sensing electrodes of the same polarity may be connected to independent outputs.

(Function) In order to provide multidirectionality (a phenomenon in which an infrared sensing element generates a sensing signal (output) when a moving object moves in the direction of the three-sided white star -H), the Sensing electrodes were arranged so as to face each other in at least two directions.

In addition, in the case of conventional multidirectional sensing electrodes arranged in concentric circles, if the area of the sensing electrodes is approximately the same and the electromotive force related to pyroelectricity against thermal changes is the same, then the sensing electrode in the center and the outer periphery There is a large difference in the amount of heat dissipated between the sensing electrodes, and in the practical temperature change range, there is a difference in the effective electromotive force of each sensing electrode (dissipated power due to electromotive car heat radiation), and temperature compensation is not performed. , a large amount of drift occurs due to temperature changes, causing erroneous signals.

In the present invention, in particular, with these points in mind, emphasis is placed on the positional relationship on the thin plate of the pair of sensing electrodes that face each other, in other words, the pair of sensing electrodes performs temperature compensation based on the principle of cancellation.

For example, the odd-numbered electrode E3 paired with the sensing electrode E1 shown in FIG. Since both are located at the corners, it can be determined that they are thermodynamically equivalent.

The only difference between these two sensing electrodes is the polarity of the electromotive force, so complete temperature compensation is achieved.

Similarly, there is another group of sensing electrodes El.

E3. E5. E7 also has other even numbers E2. E4. E6, E
8 also have completely similar positional relationships, so temperature compensation is completely satisfied.

Increasing the number of sensing electrodes while considering the above-mentioned principle will result in a multidirectional infrared sensing element, but as the number of sensing electrodes increases, the output level generated from each sensing electrode will be inversely proportional to the number of sensing electrodes. Therefore, it is easy to put it into practical use with at most 64 pieces, especially 32 pieces or less, but more than 64 pieces can be used in special cases.

Here, an embodiment of an infrared sensing element having eight sensing electrodes will be described to fully explain the principle of the present invention.

(Example) The pyroelectric thin plate is made of a polymer type, a single crystal ceramic type, etc., but in this example, a polarized ceramic type thin plate having a thickness of 200 μm or less is used. As shown in the model in Figure 3, eight sensing electrodes were arranged so as to have electromotive force with polarity as shown in the drawing.

Quantity of sensing electrodes El, E3. E5. E7 was made into a - system, and the respective polarities were determined as +l, +, and -. remaining E
2. E4. E6. Using E8 as another system, each polarity was set to 1++T I +.

When the sensing electrodes of these two systems are connected in series and in parallel as shown in the same figure C-O and C2, the moving object is -X, -Y
Each point a, b, c, d from 0 point.

The output when reaching e+f+g is e→-2 as shown in Table 2.
A signal of e→e can be obtained. However, this result is a signal common to the Y-axis direction.

Table 2 [-X-Y] Table 3 [XY] Next, the output signal when the moving body passes through the center line in the XY axis direction is as shown in Table 3. The levels are equivalent, but the polarity is reversed.

However, this result is equivalent to that in the X-axis direction. It is free to subdivide the electrical connections, take out independent signals individually, and process them in an electrical circuit as appropriate for the purpose.

For example, as shown in FIG. 3C-2, the sensing electrode El.

E2. E3. E4 system and E5. E6. E7. When the E8 system is connected in parallel, the output is as shown in Table 2.
+ b, C+ d+ e+ f+ Each output signal for the position of g is O-+e-)O→-2e
→0→-e→0, but as shown in Figure C-2, E4°E5.
E6. E7; When the system of E8 is connected in reverse as shown in parentheses, the polarity of each sensing electrode is reversed and the above a,
The output signal for the b-f, H position is 0→1→-2e→
0→2e→−1→0, and the output difference at the center is 4e, which is a characteristic output waveform.

(Effects of the Invention) According to the present invention, it is possible to obtain an infrared sensing element suitable for multi-directionality and at the same time completely temperature-compensated, so it is expected to be used in a wide range of industrial fields. It has value.

[Brief explanation of drawings]

Figures 1, 2, and 3 are model examples of typical infrared sensing elements of the present invention, and show a pyroelectric thin plate 1.
Sensing electrode El, E2. ...E8 is arranged. Also a O+ a 1 + a 2 + b O
+b 1 +b-2, c-0, c-1, and e-2 show examples of respective electrical connections. G, G
l. G2 indicates an output gate.

Claims (1)

[Claims] 1) The polarity of the sensing electrode is different from that of the sensing electrode adjacent to one or more pyroelectric thin plates, and the sensing electrode is not placed in the center, but on the center line in the vertical or horizontal direction. A method for arranging sensing electrodes for an infrared sensing element comprising four sensing electrodes, characterized in that the two sensing electrodes have the same polarity. 2) The polarity is different from that of the sensing electrode adjacent to one or more pyroelectric thin plates, and the sensing electrode is not placed in the center, either the Y axis, the X-30 degree axis, or the X+30 degree axis. If you go straight from the outside of the infrared sensing element past its center point from the direction of , the polarity of the sensing electrode is negative (positive) →
An infrared sensing element equipped with six sensing electrodes, characterized in that they are arranged in the following state: two positive electrodes (negative electrodes) → two negative electrodes (positive electrodes) → positive electrodes (negative electrodes) [The numbers in parentheses correspond to each] How to arrange sensing electrodes for use. 3) The polarity of the sensing electrodes adjacent to one or more pyroelectric thin plates is one of the same polarity and the other of different polarity. A method for arranging sensing electrodes for an infrared sensing element, characterized in that sensing electrodes having the same polarity are arranged with the center as a point of symmetry. 4) A sensing device for an infrared sensing element as described in the above claims, characterized in that the sensing electrode is not arranged in the central part and the sensing electrode is arranged so as to sense moving objects from at least two directions. How to arrange electrodes.