JP4225095B2 - Infrared sensor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an infrared sensor, and more particularly, to an infrared sensor that can suppress variation in viewing angle of the infrared sensor.
[0002]
[Prior art]
A sectional view of a general infrared sensor 11 is shown in FIG. In FIG. 4, a circuit board 2 is attached to an upper portion of a stem 1, and an infrared sensor element 3 is mounted on the circuit board 2. Three terminals 8 and the circuit board 2 are connected by wires 5. The infrared sensor element 3 is covered with a case 6 having a filter 7 in the opening.
[0003]
The infrared sensor element 3 performs output corresponding to the infrared intensity with respect to incident light in a range indicated by θ in the figure. Therefore, the viewing angle of the infrared sensor 11 varies depending on the mounting position accuracy of the infrared sensor element 3 on the circuit board 2, the accuracy of the opening of the case 6, the relative position accuracy of the infrared sensor element 3 and the opening of the case 6, and the like. Occurs.
[0004]
FIG. 5 shows the viewing angle distribution with the horizontal axis representing the angle (°) and the vertical axis representing the sensor output (v) of the infrared sensor. As for the angle, the center position of the opening of the case 6 is 0 °, the right side is (+), and the left side is (−). The output is a relative output and is normalized with the maximum output being 1.0. In the figure, a graph 50 is for a sensor having a maximum output angle on the left side from the center, and a graph 51 is for a sensor having a maximum output angle on the right side. Thus, the viewing angle distribution differs for each infrared sensor, that is, the viewing angle varies.
[0005]
In order to suppress such a variation in viewing angle, conventionally, a method of mounting the infrared sensor element 3 on the circuit board 2 with higher accuracy, a method of mounting the case 6 with accuracy with the stem 1, and the like have been employed. Furthermore, after assembling the parts, a method of measuring the viewing angle distribution and adjusting the attachment of the case 6 so that the maximum output angle becomes 0 °, for example, has been adopted.
[0006]
[Problems to be solved by the invention]
However, the conventional method has a drawback that the number of manufacturing steps is increased and the manufacturing cost is increased in order to increase the mounting accuracy or perform readjustment. Furthermore, since an infrared sensor with an inappropriate viewing angle distribution cannot be shipped, there is a problem that the yield of the infrared sensor is deteriorated.
[0007]
Accordingly, an object of the present invention is to provide an infrared sensor capable of suppressing the variation in viewing angle without increasing the manufacturing cost.
[0008]
It is another object of the present invention to provide an infrared sensor that can electrically suppress the variation in the viewing angle rather than suppressing the variation in the viewing angle during the manufacturing process.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, in the invention according to claim 1, the infrared sensor includes a plurality of infrared sensor elements for sensing infrared rays , a filter in the opening, and a first infrared sensor element and a second sensor element. a case provided so as to cover a storage unit for gain adjustment of each of the plurality of infrared sensor elements are stored, based on the gain adjustment amount to correct the viewing angle of the infrared sensor, the angle of the viewing angle to the horizontal axis (°) is taken and the sensor output (v) of the first infrared sensor element and the second infrared sensor element is taken on the vertical axis, and the angle of the viewing angle is a viewing angle distribution in which the center position of the opening of the case is 0 °. Since it has gain adjusting means for adjusting the gain of each output from the plurality of infrared sensor elements so that the maximum output angle becomes 0 °, the mounting accuracy of the infrared sensor elements and the case is taken into consideration. It is possible to obtain an effect that no, it is possible to suppress the variation of the viewing angle of the infrared sensor can.
[0010]
In the invention according to claim 1 of the present invention , the gain adjusting means can obtain the effect of correcting the viewing angle of the infrared sensor by adjusting the gain of each output from the plurality of infrared sensor elements. .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an infrared sensor according to the present invention will be described with reference to FIGS.
[0013]
A cross-sectional view of the infrared sensor 10 is shown in FIG. In FIG. 1, the same members as those in FIG. A circuit board 2 is attached to the upper portion of the stem 1, and infrared sensor elements 3 a and 3 b are mounted on the circuit board 2. Three terminals 8 and the circuit board 2 are connected by wires 5. The infrared sensor elements 3a and 3b are covered with a case 6 having a filter 7 in the opening.
[0014]
FIG. 2 shows an outline of the electronic circuit 20 mounted on the circuit board 2. In FIG. 2, the infrared sensor element 3 a is a thermopile infrared sensor and is connected to the amplifier 1. When infrared rays are incident on the infrared sensor element 3a, an output S1 corresponding to the incident infrared rays is input to the amplifier 1.
[0015]
Similarly, the infrared sensor element 3 b is a thermopile infrared sensor and is connected to the amplifier 2. When infrared rays are incident on the infrared sensor element 3b, an output S2 corresponding to the incident infrared rays is input to the amplifier 2.
[0016]
A reference input R1 is input to the amplifier 1 from the internal memory 21, and the gain of the output s1 of the infrared sensor element 3a is adjusted according to the reference input R1. Similarly, the reference input R2 is input to the amplifier 2 from the internal memory 21, and the gain of the output s2 of the infrared sensor element 3b is adjusted according to the reference input R2.
[0017]
The outputs of the amplifier 1 and the amplifier 2 are input to the arithmetic circuit 22. Each input is processed by the arithmetic circuit 22 and becomes an output of the infrared sensor 10. Note that VG indicates a band gap level, for example, 1.8V.
[0018]
Next, the manufacturing procedure of the infrared sensor 10 will be described. In the infrared sensor 10, the circuit board 2 is first mounted on the stem 1, the plurality of infrared sensor elements 3 a and 3 b are then mounted on the circuit board 2, and then the circuit board 2 and each terminal 8 are connected by wires 5. Is done. Thereafter, the case 6 having the infrared filter 7 attached to the opening is welded and fixed onto the stem 1.
[0019]
Next, the viewing angle correction procedure of the infrared sensor 10, that is, the electric trimming process will be described.
[0020]
First, after the manufacturing of the infrared sensor 10 is completed, the viewing angle distribution is measured for each infrared sensor element (3a and 3b). An example of the measured viewing angle distribution is shown in FIG. In FIG. 3, the viewing angle distribution of the infrared sensor element 3a is 30 and the viewing angle distribution of the infrared sensor element 3b is 31.
[0021]
Next, the gain of the output from each infrared sensor element 3a and 3b is adjusted. In the example of FIG. 3, when the output from the infrared sensor element 3a and the output from the infrared sensor element 3b are added, the infrared sensor element 3a has a viewing angle distribution (see graph 33 in FIG. 3) without variation. Is adjusted so that the output of the infrared sensor element 3b remains as it is. The set gain adjustment amount is written in the internal memory 21 as the reference inputs R1 and R2.
[0022]
The gain-adjusted outputs S 1 and S 2 are added by the arithmetic circuit 22, that is, subjected to electrical trimming, and become the output of the infrared sensor 10.
[0023]
As shown in FIG. 3, the viewing angle distribution 33 of the infrared sensor 10 subjected to the electrical trimming process is adjusted so that the maximum output angle is 0 °.
[0024]
In the example of FIG. 2, the gain adjustment is performed using the two amplifiers 1 and 2, but by configuring the switch means to switch the reference inputs R <b> 1 and R <b> 2 from the internal memory 21, It is possible to adjust the gain with only one amplifier.
[0025]
Further, in the above-described embodiment, the output from the two infrared sensor elements 3a and 3b is configured to be electrically trimmed. However, if the number of infrared sensor elements is increased, the field of view of the sensor output of the infrared sensor can be increased with higher accuracy. It becomes possible to correct the angular distribution.
[0026]
As described above, the infrared sensor can suppress the variation in the viewing angle distribution of the infrared sensor by performing the electric trimming process on the output from the plurality of infrared sensor elements. That is, it has become possible to obtain an infrared sensor having a viewing angle distribution that is electrically absorbed by the variation in assembly of the infrared sensor element and the case that has occurred during manufacture and has no variation.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a cross-sectional view of an infrared sensor according to the present invention.
FIG. 2 is a diagram showing an example of an electronic circuit assembled in the infrared sensor according to the present invention.
FIG. 3 is a diagram for explaining correction of a viewing angle distribution.
FIG. 4 is a diagram showing an example of a cross-sectional view of a conventional infrared sensor.
FIG. 5 is a diagram for explaining variation in viewing angle distribution;
[Explanation of symbols]
2 ... electronic circuit 3, 3a, 3b ... infrared sensor element 6 ... case 10, 11 ... infrared sensor 20 ... electronic circuit 21 ... internal memory 22 ... arithmetic circuit

Claims (1)

A first infrared sensor element for detecting infrared rays; a second infrared sensor element for detecting infrared rays; a case having a filter in an opening and provided to cover the first infrared sensor element and the second sensor element; Based on the storage means storing the first gain adjustment amount for the first infrared sensor element and the second gain adjustment amount for the second infrared sensor element, and the first and second gain adjustment amounts. The viewing angle of the infrared sensor is corrected , the viewing angle (°) is taken on the horizontal axis, the sensor outputs (v) of the first infrared sensor element and the second infrared sensor element are taken on the vertical axis, and the viewing angle is taken. the angle in the viewing angle distribution of the center position of the opening was set to 0 ° in the case, a gain adjustment means for adjusting the gain of the output of the first and 2 infrared sensor element such that the maximum output angle is 0 ° Infrared sensor characterized in that it comprises.

Images