JP2015197311A - infrared sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an output signal from a sub-field of vision in an infrared sensor.SOLUTION: An infrared sensor device according to the present invention comprises a sensor unit having a photodetector for outputting a signal corresponding to an incident infrared ray, a resin package formed so as to wrap the photodetector therein via an opening, and an optical filter provided inside the opening. The opening is configured from a first opening, a second opening, and a third opening. The first opening is open to the outside of the resin package, filled with the optical filter, and is contiguously arranged with the second and third openings in the vertical direction so as to constitute a gap on the light-receiving side of the photodetector. The third opening is arranged on the sensor unit side, and the second opening is arranged between the first and the third openings so that it communicates with both the first and the third openings, the aperture areas of the first and third openings being larger than the aperture diameter of the second opening.

Description

  The present invention relates to an infrared sensor, and more particularly to an infrared sensor that limits a viewing angle.

  Sensors are known for converting physical changes such as temperature, pressure, and light into electrical changes such as current and voltage. By using a sensor, various physical changes can be measured as numerical values. In particular, sensors that can contribute to energy saving and higher efficiency are attracting attention due to recent interest in environmental issues.

  Among the sensors described above, there is an infrared sensor that detects the amount of change in infrared rays and converts infrared rays into electrical signals. Infrared sensors are used in television remote control devices and the like because they can transmit information without affecting human eyes.

  Further, the infrared sensor has a feature that it can sense the temperature of an object without directly contacting it, and the infrared sensor can be used as a human sensor for sensing a heat source such as a human body or a non-contact thermometer. For example, when an infrared sensor is used as a human sensor, unnecessary power can be effectively reduced by mounting the infrared sensor on illumination or the like. In addition, for gases having an absorption band in the infrared region (carbon dioxide, carbon monoxide, etc.), the infrared sensor can be applied as a gas sensor, and is expected to be used in various applications rather than human sensors. Has been.

  Infrared sensors are classified into thermal sensors and quantum sensors based on their operating principles. Thermal sensors are widely used in human sensors, but have a problem of low frequency response. Further, when the thermal sensor is used as a gas sensor, the gas detection response is low, and there is a problem in terms of rapid abnormality detection.

  On the other hand, the quantum sensor is characterized by high frequency response, and is very promising in this respect compared to the thermal sensor.

JP-A-6-67013

  The infrared sensor reduces the influence of disturbance light from other than the measurement object, and an opening for narrowing the viewing angle is formed in order to accurately output a signal corresponding to the incident infrared light from a predetermined viewing field range. There is known a form in which the structured body is provided. There is also known a configuration in which a plurality of light receiving bodies of the infrared sensor are provided independently and an opening is provided in the structure for each light receiving body. Signal output characteristics for different visual fields are given to the respective photoreceptors, and the position of the object can be detected using signals from the respective photoreceptors having different visual fields.

  Patent Document 1 discloses an optical sensor having an optical filter partitioned by an optical partition that limits the field of incident light incident on the infrared sensor. The infrared sensor of patent document 1 can consider the structure which restrict | limits the visual field of the infrared rays which partition an optical filter by an optical partition, and inject into an infrared sensor light-receiving body.

  FIG. 1 is a cross-sectional view showing a configuration of an infrared sensor device 100 described in Patent Document 1. As shown in FIG. The infrared sensor 100 includes an infrared sensor unit 110 having a plurality of light receivers 111 that output signals corresponding to incident infrared rays, an optical partition 120 that limits the field of view of the light receiver 111, and an optical filter 130 that is partitioned by the optical partition 120. With.

  In the infrared sensor device 100 shown in FIG. 1, there are two types of visual fields: a main visual field that is not reflected by the side surface of the filter due to the influence of light reflection by the side surface (optical partition wall 120) of the optical filter 130, and a sub field by the reflection of the side surface of the optical filter. Occurs. In this case, as can be seen from FIG. 1, the infrared light incident from the sub-field (outside the main field) is refracted by the optical filter 130, reflected by the optical partition 120, and reaches the photoreceptor 111. Therefore, disturbance light reaches the light receiving unit 111, and there is a problem that infrared detection with high accuracy in the main visual field cannot be performed. In addition, when there are a plurality of independent photoreceptors, it is difficult to determine the magnitude relationship of the output results due to the influence of the subfield.

  In order to solve such a problem, the infrared sensor according to the first aspect of the present invention includes a sensor unit having a light receiving body that outputs a signal corresponding to incident infrared light, and the light receiving body through an opening. An infrared sensor comprising a resin package formed so as to be wrapped and an optical filter provided in the opening, wherein the opening includes a first opening, a second opening, and a third opening. The first opening is open to the outside of the resin package, is filled with the optical filter, and the second opening and the third opening are on the light receiving surface side of the photoreceptor. The third opening is disposed on the sensor unit side, and the second opening is disposed between the first opening and the third opening. Connected to both the first opening and the third opening Arranged to the opening area and the opening area of the third opening of the first opening, being greater than the opening diameter of the second opening.

In the infrared sensor of the second aspect of the present invention, the width in the light receiving surface direction of the photoreceptor is L, the width in the light receiving surface direction of the optical filter is d ₁ , and the light receiving surface of the optical filter is The thickness in the vertical direction is h ₁ , the refractive index of the optical filter is n ₂ , the width in the light receiving surface direction of the second opening is the width d ₂ , and the light receiving side end surface of the optical filter is connected to the light receiving body. L, d ₁ , h ₁ , n ₂ , d ₂ , h, and n _1, where h is the vertical distance and n ₁ is the refractive index of air,

  It satisfies the following formula.

  The width in the light receiving surface direction of the light receiver is x, the width in the light receiving surface direction of the second opening of the optical filter is δ, and the vertical direction from the light receiving side end surface of the optical filter to the light receiving body is the vertical direction. When the distance is h and the thickness of the second opening in the light receiving surface direction is Z, the x, δ, h, and Z are

  It satisfies the following formula.

  The infrared sensor of the fourth aspect of the present invention is the infrared sensor according to any one of the first to third aspects, wherein the resin package has an emissivity of 0.7 or more. Features.

  According to the infrared sensor device of the present invention, it is possible to reduce the output signal from the sub-field that causes the influence of disturbance light, and to accurately quantify the amount of infrared light in the main field.

It is a cross-sectional schematic diagram which shows the structure of the infrared sensor of patent document 1. FIG. It is a top view which shows the structural example of the infrared sensor of one Embodiment of this invention. It is sectional drawing in AA 'of the infrared sensor of FIG. It is the figure which added the optical path etc. for demonstrating Formula (1) to sectional drawing of the infrared sensor of FIG. It is the figure which added the optical path etc. for demonstrating Formula (2) to sectional drawing of the infrared sensor of FIG. It is sectional drawing which shows the visual field of the infrared sensor of FIG. It is sectional drawing which shows the visual field of the conventional infrared sensor.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 2 is a plan view showing a configuration example of the infrared sensor 200 according to the embodiment of the present invention. 3 is a cross-sectional view taken along line AA ′ of the infrared sensor 200 shown in FIG. In FIG. 3, the infrared sensor 200 is provided on one side (upper surface) of a sensor unit 210 having a photoreceptor 211, and on the upper surface side of the sensor unit 210, so as to wrap the photoreceptor 211 through an opening 221. A formed resin package 220 and an optical filter 230 provided in the opening 221 are provided. The resin package is formed of a material having an emissivity of 0.7 or more.

  The photoreceptor 211 outputs an electrical signal corresponding to the incident infrared ray. In addition, the photoreceptor 211 is provided with the resin package 220 in which the opening 221 is formed on the upper surface of the sensor unit 210, so that the viewing angle is limited. The viewing angle of the photoreceptor 211 is limited within a certain angle by the opening diameter and opening depth of the resin package 220.

  The opening 221 opens with respect to the surface (resin package upper surface) opposite to the surface on which the sensor unit 210 of the resin package 220 is provided. The first opening 221a, the second opening 221b, and the third opening Part 221c. Here, the first opening 221 a opens to the outside of the resin package 220 and is filled with the optical filter 230. In the present embodiment, the first opening 221a, the second opening 221b, and the third opening 221c are formed in a prismatic shape.

  The second opening 221b and the third opening 221c are continuously arranged in the vertical direction so as to be a gap on the light receiving surface side of the photoreceptor 211, and the third opening 221c is arranged on the sensor unit 211 side. The two openings 221b are disposed between the first opening 221a and the third opening 221c. The second opening 221b communicates with both the first opening 221a and the third opening 221c.

  Returning to FIG. 2 again, when the infrared sensor 200 is viewed in plan, the outer edge of the second opening 221b is disposed within the outer edges of the first opening 221a and the third opening 221c. That is, the opening diameter of the first opening 221a and the opening area of the third opening 221c are larger than the opening area of the second opening 221b.

  By arranging the outer edge of the second opening 221b in the outer edge of the first opening 221a and the third opening 221c, the opening wall in the first opening 221a of the resin package 220 (the side surface of the optical filter 230). ) Is reflected or absorbed by the resin package wall forming the second opening 221b without entering the second opening 221b. Therefore, it is possible to reduce the incident light of the infrared rays from the sub visual field to the photoreceptor 211 and to quantify the amount of infrared rays incident from the main visual field with high accuracy.

Here, in the present embodiment, the dimensions of the infrared sensor 200 are specifically designed as follows. First, parameters indicating dimensions of each component of the infrared sensor 200 illustrated in FIG. 2 are set as follows.
L: width d _{1 of the} photoreceptor 211 (in the x-axis direction): width h _{1 of the} optical filter 230 (in the x-axis direction): thickness d _{2 of the} optical filter 230 (in the z-axis direction) d: of the second opening 221b Width h (in the x-axis direction): Distance (in the z-axis direction) from the photoreceptor 211 to the end surface of the optical filter 230 on the side of the photoreceptor 211 h ₂ : Thickness n _{1 in} the second opening 221b (in the z-axis direction): Refractive index n _{2 of} air: Refractive index of optical filter 230 Next, parameters L, d ₁ , h ₁ , d ₂ , h, n ₁ , and n _{2 of} each component are set so as to satisfy the following formula (1). To do.

Further, L, d ₂ , h, and h ₂ are set so as to satisfy the following formula (2).

  Here, the infrared sensor 200 of the present embodiment has a first opening 221a to a third opening when viewed in cross section in order to efficiently reduce the output signal from the sub-field and accurately quantify the amount of infrared in the main field. It is preferable that the center of gravity of the portion 221c and the center of the photoreceptor 211 are arranged in a straight line.

  Hereinafter, the technical significance of Formula (1) and Formula (2) will be described with reference to the drawings.

  FIG. 4 is a cross-sectional view showing the infrared sensor 200 of FIG. 2 with an optical path and the like for explaining the formula (1).

4, the end point _{k 1} of a third opening 221c side of the photoreceptor 211, connected by a line and end point _{k 2} of the first opening 211a side of the second opening 221b, the line segment a line segment connecting 1 And A vertical line with respect to the light-receiving surface of the photoreceptor 211 from the end point _{k 2} of the first opening 211a side of the second opening 221b, and the segment 2 to segment minus. Further, the intersection of the line segment 2 and the light receiving surface of the photoreceptor 211 is denoted by k ₃ . When θ ₁ is an angle formed by the line segment 1 and the line segment 2, the following expression (3) is established for the parameters L, d ₂ , h, and θ ₁ .

The end point k ₂ of the first opening 221 a on the second opening 221 b side is connected to the end point k ₄ on the opening side of the first opening 221 a with a line, and the connected line segment is defined as a line segment 3. Then, a point which intersects the opening of the first opening portion 221a by extending the line segments 2, k _5. An angle formed by the line segment 3 and the line segment 2 is defined as θ ₂ .

Here, the line segment 2, consider the optical path of the light beam incident on the optical filter 230 in the first opening 221a is reflected from the resin package 220 outside the end point _{k 4,} the line segment 1, through the first opening 221a through the second opening 221b, and a third opening 221c considered optical paths of light rays incident on the end point _{k 1} of the light receiving member 211. Angle of incidence from the resin package 220 external to the optical filter 230 in the first opening 221a is theta _2, the angle of incidence is the theta ₁ from the optical filter 230 in the first opening 221a into the second opening 221b . For the parameters θ ₁ , θ ₂ , n ₁ , and n ₂ , the following equation (4) is established.

When the distance P between the line segment connecting k ₄ and k ₅ satisfies the relationship of the following formula (5) between the parameters d ₁ and d ₂ , the infrared ray reflected by the side surface of the optical filter 230 is received by the photoreceptor 211. Can be reduced.

Furthermore, P, h ₁ and θ ₂ satisfy the relationship of the following formula (6).

  Solving Equation (6) for P yields Equation (7) below.

  When the equation (7) is factorized, the following equation (8) is derived.

  The following equation (9) is derived from the equations (8) and (5).

  The following equation (10) is derived from the equations (9) and (4).

  Then, Expression (1) is calculated from Expression (10) and Expression (3).

  That is, if Expression (1) is satisfied, it is possible to efficiently reduce the incidence of infrared rays from other than the desired field of view.

  Next, the technical significance of the formula (2) will be described.

  FIG. 5 is a cross-sectional view of the infrared sensor device 200 of the present embodiment in FIG. 2 with an optical path and the like for explaining the formula (2).

5, the two end points _{k 6} and _{k 7} of the third opening 221c of the second opening portion 221b connected by a line, the line connecting the segment 4, and segment 1 (identical to Figure 4) line minute 4 of the intersection and _{k 8.} It signed a k ₇ and _{k 8} the length of the line segment and Q. If Q is larger than d ₂ , the second opening 221b shields the light incident on the end of the photoreceptor 211, so the main field of view of the photoreceptor 211 is narrowed. Therefore, when d ₂ and Q satisfy the following formula (11), it is possible to prevent the second opening 221 b from blocking the optical path of the main field of view of the photoreceptor 211.

A line segment connecting the end point k ₁ (same as FIG. 4) and the intersection k ₃ (same as FIG. 4) is defined as a line segment 5. Here, since the triangle formed by the line segment 1, the line segment 2, and the line segment 5 is similar to the triangle formed by the line segment 1, the line segment 2, and the line segment 4, the equation (12) of the ratio of each side is established.

  Then, the value of Q can be calculated (Formula (13)).

  From the equations (11) and (13), the relationship of the following equation (14) is obtained.

Summarizing equation (14) for d ₂ , equation (2) can be derived.

  FIG. 6 is a cross-sectional view for explaining the field of view of the infrared sensor device shown in FIGS. 2 and 3. In FIG. 6, the range indicated by the broken line is the range of the main visual field when reflection on the side surface of the optical filter 230 (the wall surface of the first opening 221a) is not considered.

  Here, a part of infrared rays (indicated by a solid line) output from outside the main field of view (sub-field of view) enters the optical filter 230 and is refracted, and is incident on the side surface of the optical filter 230 (the wall surface of the first opening 221a). reflect. However, it is understood that the optical path is shielded by the resin package that forms the bottom wall surface of the first opening 221a and does not enter the second opening 221b.

  That is, when the resin package 220 is arranged on the sensor unit 210 so that the second opening 221b and the third opening 221c are hollow portions on the photoreceptor 211, the first view is obtained when the infrared sensor device 200 is viewed in plan. Arranging the outer edge of the second opening 221b within the outer edges of the opening 221a and the third opening 221c reduces the arrival of infrared rays from the sub-field to the photoreceptor 211 and makes it incident from the main field. It is understood that the amount of infrared rays can be quantified with high accuracy.

On the other hand, FIG. 7 is a schematic cross-sectional view for explaining the field of view of a conventional infrared sensor device. The opening (corresponding to the first opening 221a in FIG. 2) in which the optical filter unit is disposed and the opening below (corresponding to the second opening 221b in FIG. 2) have the same shape (when viewed in cross section) The width is the same, and the outer edges overlap when viewed in plan). As can be seen from FIG. 7, it is understood that the infrared light incident from the sub-field (outside the main field) reaches the photoreceptor by refraction and reflection in the optical filter. Each of the infrared sensor devices of the present embodiment will be described below. The configuration requirements will be described. The following description can be applied to the above-described infrared sensor devices independently or in combination.

(Sensor unit)
Examples of the infrared sensor used in the sensor unit 210 include a thermal infrared sensor, a quantum infrared sensor, and the like. From the viewpoints of sensitivity and responsiveness, a quantum infrared sensor is preferable. The sensor unit 210 may include a substrate that supports the photoreceptor 211 as necessary.

  There may be one photoreceptor 211 or a plurality of photoreceptors. When there are a plurality of light receiving bodies 211, it is applied as an infrared sensor device for position detection using the magnitude relation of the magnitude of each signal output from each light receiving body and motion detection using the differential value of each signal change. Is possible. Here, each photoreceptor has a different field of view, and at this time, each of the photoreceptors has a sub-field. That is, the main field of view for one photoreceptor is a sub-field (outside the main field) for another photoreceptor.

  In the conventional infrared sensor device, since the infrared rays from the sub field of view can reach the photoreceptor, the above-described misdetection of position detection and motion detection occurs. Therefore, position detection and motion detection can be performed with higher accuracy.

  The infrared sensor device 200 may further include a circuit unit for amplifying and calculating a signal output from the photoreceptor 211.

(Resin package)
The first opening 221a to the third opening 221c formed in the resin package 220 are formed in a prismatic shape in this embodiment, but the first opening 221a and the third opening 221c If the outer edge of the 2nd opening part 221b is arrange | positioned in an outer edge, it will not restrict | limit in particular, Not only prismatic shape but cylindrical shape may be sufficient. The material constituting the resin package is not particularly limited as long as the emissivity is 0.7 or more, and examples thereof include a thermosetting epoxy resin.

  From the viewpoint of efficiently reducing the infrared rays from the sub-field of view, the angle formed by the side surfaces of the first opening 221a to the third opening 221c (the inner wall surface of the resin package 220) and the plane of the photoreceptor 211 is 90 ± 5 °. Preferably there is.

(Optical filter)
The optical filter 230 selectively transmits incident infrared rays, and may transmit light having a predetermined wavelength or more, or may transmit light having a predetermined wavelength or less. However, it may transmit a wavelength in a predetermined band. Moreover, it may be composed of a plurality of materials. Specific examples of the material for the optical filter 230 include Si. From the viewpoint of blocking ambient light and preventing entry of foreign matter, the optical filter 230 preferably fills the first opening.

  The present invention is suitable as an infrared sensor device applied to position detection and motion detection.

100, 200 Infrared sensor 110, 210 Sensor unit 111, 211 Photoreceptor 120 Optical partition wall 130, 230 Optical filter 220 Resin packages 221, 221a, 221b, 221c Openings k ₁ -k ₈ points

Claims (4)

A sensor unit having a photoreceptor that outputs a signal corresponding to incident infrared rays;
A resin package formed so as to wrap the photoreceptor through an opening;
An infrared sensor comprising an optical filter provided in the opening,
The opening is composed of a first opening, a second opening, and a third opening. The first opening opens to the outside of the resin package, and is filled with the optical filter. The second opening and the third opening are continuously arranged in a vertical direction so as to be a gap on the light receiving surface side of the photoreceptor, and the third opening is on the sensor unit side, The second opening is disposed between the first opening and the third opening so as to communicate with both the first opening and the third opening.
The infrared sensor, wherein an opening area of the first opening and an opening area of the third opening are larger than an opening diameter of the second opening. The width in the light receiving surface direction of the photoreceptor is L, the width in the light receiving surface direction of the optical filter is d ₁ , the thickness in the direction perpendicular to the light receiving surface of the optical filter is h ₁ , and the refractive index of the optical filter N ₂ , the width of the second opening in the light receiving surface direction is d ₂ , the vertical distance from the light receiving body side end surface of the optical filter to the light receiving body is h, and the refractive index of air is n _1. When L, d ₁ , h ₁ , n ₂ , d ₂ , h, and n ₁ are

The infrared sensor according to claim 1, wherein: The width in the light receiving surface direction of the light receiver is x, the width in the light receiving surface direction of the second opening of the optical filter is δ, and the vertical direction from the light receiving side end surface of the optical filter to the light receiving body is the vertical direction. When the distance is h and the thickness of the second opening in the light receiving surface direction is Z, the x, δ, h, and Z are

The infrared sensor according to claim 1, wherein the following equation is satisfied.   The infrared sensor according to claim 1, wherein the resin package has an emissivity of 0.7 or more.

Images