JP2014130056A - Infrared sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an infrared sensor capable of reducing distortion of field of view with a simple structure.SOLUTION: The infrared sensor includes: a board 1; a sensor chip 2 mounted on the upper face of the board 1, which has plural light receiving elements arranged in a lattice shape on the upper face, to output a signal corresponding to the infrared ray received by the plural light receiving elements; and a lens 5 disposed above the sensor chip 2 parallel to the plural light receiving elements so that the center of which is away from a vertical line passing through the center of the plural light receiving elements to focus the infrared ray on the plural light receiving element.

Description

  The present invention relates to an infrared sensor that detects infrared rays.

  There is known an infrared sensor including a sensor chip provided with light receiving elements arranged in a grid and a lens that forms an infrared image on the sensor chip (see Patent Document 1). In such an infrared sensor, the optical axis of the visual field is determined by the relative positional relationship between the sensor chip and the lens. A general infrared sensor is designed so that the optical axis of the field of view is perpendicular to the sensor chip. When detecting a visual field in an oblique direction with respect to a horizontal plane, the infrared sensor detects an infrared ray within a viewing angle by being installed at an inclination or by installing a mirror in front of the infrared sensor.

JP 2012-198096 A

  When the infrared sensor is set to be inclined with respect to the horizontal plane, the detection visual field is distorted into a trapezoid because the detection area for one pixel of the sensor chip is different between the near side and the far side of the visual field. On the other hand, when installing a mirror, it is necessary to externally attach another part, and there exists a problem which the size and manufacturing cost of an apparatus increase.

  In view of the above problems, an object of the present invention is to provide an infrared sensor that reduces distortion of the visual field with a simple configuration.

  In order to achieve the above object, according to a first aspect of the present invention, there is provided a substrate and a plurality of light receiving elements mounted on the upper surface of the substrate and arranged in a lattice pattern on the upper surface. A sensor chip that outputs a signal corresponding to the received infrared light, and a center disposed above the sensor chip in parallel with the plurality of light receiving elements so as to be separated from a perpendicular passing through the centers of the plurality of light receiving elements. The gist of the present invention is an infrared sensor including a lens that forms an infrared image on the plurality of light receiving elements.

  In the infrared sensor according to the first aspect of the present invention, the infrared sensor according to the first aspect of the present invention further includes a case having a first incident window that is installed on the substrate and allows infrared light to be incident on the sensor chip, and the case includes the first incident window. It is possible to hold the lens.

  Moreover, in the infrared sensor according to the first aspect of the present invention, an integrated circuit that is mounted on the upper surface of the substrate and that processes a signal output from the sensor chip, covers the sensor chip and the integrated circuit, and transmits infrared light. And a shield cover having a second incident window that is incident on the sensor chip.

  In the infrared sensor according to the first aspect of the present invention, the center of the lens can be separated from the perpendicular passing through the centers of the plurality of light receiving elements toward the integrated circuit.

  ADVANTAGE OF THE INVENTION According to this invention, the infrared sensor which reduces distortion of a visual field with simple structure can be provided.

It is a typical perspective view explaining the fundamental structure of the infrared sensor which concerns on embodiment of this invention. It is a typical perspective view explaining the board | substrate, sensor chip, and IC with which the infrared sensor which concerns on embodiment of this invention is provided. It is a typical perspective view explaining the lens with which the infrared sensor which concerns on embodiment of this invention is provided, and a case. It is typical sectional drawing explaining the fundamental structure of the infrared sensor which concerns on embodiment of this invention. It is a schematic diagram explaining operation | movement of the infrared sensor which concerns on embodiment of this invention. It is an example which illustrated the detection visual field of the infrared sensor which concerns on embodiment of this invention. It is typical sectional drawing explaining the basic composition of the infrared sensor which has a perpendicular optical axis. It is a schematic diagram explaining operation | movement of the infrared sensor which has a perpendicular | vertical optical axis. It is an example which illustrated the detection visual field of the infrared sensor which has a perpendicular optical axis.

  Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings. Further, the embodiment described below exemplifies an apparatus and a method for embodying the technical idea of the present invention, and the technical idea of the present invention is the material, shape, structure, The layout is not specified as follows. The technical idea of the present invention can be variously modified within the technical scope described in the claims.

(Infrared sensor)
As shown in FIG. 1, the infrared sensor according to the embodiment of the present invention includes a substrate 1, a sensor chip 2, an integrated circuit (IC) 3, a shield cover 4, a lens 5, and a case 6. . The infrared sensor according to the embodiment of the present invention receives infrared rays and detects, for example, a temperature distribution and the presence / absence of a heat source.

  The substrate 1 is generally a rectangular flat plate, and is composed of a multilayer substrate such as a ceramic substrate or a resin-based printed substrate. The substrate 1 is formed with circuit wiring connected to the sensor chip 2, the IC 3, and the like. As shown in FIG. 2, the substrate 1 is connected to the ground potential on the upper surface, and the thermistor that detects the temperature in order to correct the temperature detected by the bonding electrode 11 bonded to the case 6 and the sensor chip 2. 12 etc. are formed. The bonding electrode 11 is formed in a frame shape so as to border the upper surface of the substrate 1.

  The sensor chip 2 has a generally rectangular flat plate shape, and is mounted on the upper surface of the substrate 1 by, for example, die bonding. The sensor chip 2 has a plurality of light receiving elements arranged in a lattice pattern on the upper surface as a light receiving surface. Each of the plurality of light receiving elements of the sensor chip 2 receives infrared rays and outputs an output signal corresponding to the intensity of the received infrared rays.

  The plurality of light receiving elements of the sensor chip 2 are, for example, light receiving elements of 64 pixels arranged in an 8 × 8 square lattice. The plurality of light receiving elements of the sensor chip 2 are arranged so that one of the grid lines orthogonal to the array pattern is in a direction along the longitudinal direction of the substrate 1. The plurality of light receiving elements of the sensor chip 2 are composed of, for example, thermopiles arranged in a lattice pattern. As the sensor chip 2, a pyroelectric infrared sensor, a quantum infrared sensor, or the like can be used. The sensor chip 2 is connected to the circuit wiring of the substrate 1 and the terminals of the IC 3 by, for example, wire bonding or flip chip.

  The IC 3 is mounted in the vicinity of the sensor chip 2 on the upper surface of the substrate 1 by, for example, die bonding. The IC 3 and the sensor chip 2 are arranged side by side along the longitudinal direction of the substrate 1. The IC 3 processes an output signal output from the sensor chip 2 and performs detection processing such as temperature distribution and presence / absence of a heat source based on the output signal of the sensor chip 2. The sensor chip 2 is connected to the circuit wiring of the substrate 1 and the output terminal of the sensor chip 2 by wire bonding or flip chip, for example.

  The shield cover 4 blocks infrared rays that are incident on the sensor chip 2 and infrared rays that are incident on the IC 3 from other than the target to detect infrared rays. The shield cover 4 is generally rectangular parallelepiped box-shaped, and opens on the entire lower surface. The shield cover 4 is joined to the substrate 1 with a conductive resin or the like at the lower end of the side wall so as to cover the sensor chip 2 and the IC 3. The shield cover 4 is made of a metal material such as Kovar, for example. The shield cover 4 has a rectangular incident window 40 on a part of the upper surface above the sensor chip 2. The incident window 40 is transparent to infrared rays, and is, for example, a through hole. The incident window 40 allows infrared light to enter the light receiving surface of the sensor chip 2. The center of the entrance window 40 is separated from the perpendicular passing through the center of the light receiving surface of the sensor chip 2 in the plan view toward the IC 3 side.

  The lens 5 is generally a rectangular flat plate, and is a convex lens in which one surface (upper surface) is a flat surface and the other surface (lower surface) is a convex surface. The lens 5 is arranged above the sensor chip 2 in parallel with the light receiving surface of the sensor chip 2 so that the center is separated from a perpendicular line passing through the center of the light receiving surface of the sensor chip 2. The lens 5 is configured to form an infrared image on the light receiving surface of the sensor chip 2. The lens 5 only needs to have a function of condensing on the light receiving surface of the sensor chip 2. For example, the lens 5 may be formed with convex surfaces on both sides, or one surface with a concave surface and the other surface with a convex surface having a larger curvature than the concave surface. The convex surface and concave surface of the lens 5 may have various curvatures such as a paraboloid.

  The case 6 is roughly a rectangular parallelepiped box shape, and opens on the entire lower surface. Case 6 is made of metal. The case 6 is installed on the substrate 1 by bonding the lower end of the side wall portion to the bonding electrode 11 of the substrate 1 with a conductive resin or the like so as to cover the shield cover 4. The case 6 has a rectangular incident window 60 on a part of the upper surface above the sensor chip 2. The incident window 60 is transparent to infrared rays, and is, for example, a through hole. The center of the incident window 60 is separated from the perpendicular passing through the center of the light receiving surface of the sensor chip 2 in the plan view toward the IC 3 side.

  As shown in FIG. 3, the entrance window 60 has a rectangular shape along the lens 5 so that the upper surface of the lens 5 can be joined to the periphery of the entrance window 60 from below the case 6. The entrance window 60 holds the lens 5 by bonding the upper surface of the lens 5 to the periphery. In addition, the incident window 60 may be circular, elliptical, or the like. The incident window 60 causes infrared light to enter the light receiving surface of the sensor chip 2 through the lens 5. The center of the incident window 40 of the shield cover 4 is located, for example, between the center of the lens 5 and the center of the light receiving surface of the sensor chip 2. In the case 6, the lens 5 is bonded around the entrance window 60 with resin or the like, and the lower end portion of the side wall portion is bonded to the bonding electrode 11 of the substrate 1 to seal the inside.

  As shown in FIG. 4, the lens 5 is arranged so that the center has a predetermined angle θ with respect to a perpendicular passing through the center of the light receiving surface of the sensor chip 2. The center of the lens 5 is separated from the perpendicular passing through the center of the light receiving surface of the sensor chip 2 in the plan view toward the IC 3 side. The viewing angle A of the detection visual field of the infrared sensor according to the embodiment of the present invention is determined by the shape, arrangement, and the like of the sensor chip 2, the incident window 40, the lens 5, and the incident window 60. The optical axis B of the detection visual field of the infrared sensor according to the embodiment of the present invention is determined by the angle θ. That is, the optical axis B is located on a straight line connecting the center of the lens 5 and the center of the light receiving surface of the sensor chip 2 and is inclined by an angle θ with respect to the infrared sensor according to the embodiment of the present invention.

  For example, as shown in FIG. 5, the angle θ is 15 °, and the infrared sensor according to the embodiment of the present invention is such that the longitudinal direction of the substrate 1 changes from the vertical direction (Y-axis direction) to the detection direction (X-axis direction). Let us consider a case where infrared rays are detected toward a horizontal plane (XZ plane) P in a state inclined by 30 °. In this case, the optical axis B is inclined 45 ° with respect to the vertical direction. The visual field Q detected by the sensor chip 2 of the infrared sensor according to the embodiment of the present invention is formed in a trapezoidal shape on the horizontal plane P as shown in FIG.

  As shown in FIG. 7, using the infrared sensor S configured so that the center of the lens 5 is located on a perpendicular line passing through the center of the light receiving surface of the sensor chip 2, as in the example shown in FIG. Consider a case where infrared rays are detected toward the horizontal plane P so that the axis B is inclined by 45 ° with respect to the vertical direction. The incident windows of the shield cover 4p and the case 6p included in the infrared sensor S are centered on a vertical line passing through the center of the light receiving surface of the sensor chip 2, and the optical axis B of the infrared sensor S is It coincides with a perpendicular passing through the center of the light receiving surface.

  As shown in FIG. 8, the infrared sensor S in which the optical axis B is formed vertically detects infrared rays toward the horizontal plane P in a state where the substrate 1 is inclined 45 ° in the detection direction from the vertical direction. As shown in FIG. 9, the visual field Q detected by the sensor chip 2 of the infrared sensor S is formed in a trapezoidal shape having a larger distortion than the visual field Q shown in FIG.

  As described above, the infrared sensor according to the embodiment of the present invention has a corner angle that is greater than that of the infrared sensor S configured such that the center of the lens 5 is located on a perpendicular line passing through the center of the light receiving surface of the sensor chip 2. The overlap of the field of view of the pixels is large, and the distortion of the field of view Q is small. In addition, the infrared sensor according to the embodiment of the present invention has a viewing angle A like the infrared sensor S.

  According to the infrared sensor according to the embodiment of the present invention, since the center of the lens 5 is separated from the perpendicular passing through the center of the light receiving surface of the sensor chip 2, the distortion of the visual field can be reduced with a simple configuration.

  Further, according to the infrared sensor according to the embodiment of the present invention, the center of the lens 5 is separated from the perpendicular passing through the center of the light receiving surface of the sensor chip 2 toward the IC 3 side, so that a space for shifting the lens 5 can be secured. The inclination of the optical axis B can be increased without increasing the size.

(Other embodiments)
As mentioned above, although this invention was described by embodiment, it should not be understood that the description and drawing which form a part of this indication limit this invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, in the above-described embodiment of the present invention, the infrared sensor may be configured to be held by the shield cover 4 by bonding the lens 5 around the entrance window 40 of the shield cover 4. Good.

  In the embodiment already described, the planar pattern of the lens 5 is not limited to a rectangle, but may be a circle or the like. In this case, the plane pattern of the entrance window 40 or the entrance window 60 to which the lens 5 is bonded may be deformed according to the plane pattern of the lens 5.

  As described above, the present invention naturally includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

1 Substrate 2 Sensor chip 3 Integrated circuit (IC)
4 Shield cover 5 Lens 6 Case 40 Entrance window 60 Entrance window

Claims (4)

A substrate,
A sensor chip mounted on the upper surface of the substrate and having a plurality of light receiving elements arranged in a lattice pattern on the upper surface, and outputting a signal corresponding to infrared rays received by the plurality of light receiving elements;
A lens that is disposed above the sensor chip in parallel with the plurality of light receiving elements so that a center is separated from a perpendicular line passing through the centers of the plurality of light receiving elements, and that forms an infrared ray on the plurality of light receiving elements; An infrared sensor comprising: A case having a first incident window installed on the substrate and allowing infrared rays to be incident on the sensor chip;
The infrared sensor according to claim 1, wherein the case holds the lens in the first incident window. An integrated circuit mounted on an upper surface of the substrate and processing a signal output from the sensor chip;
The infrared sensor according to claim 2, further comprising: a shield cover that covers the sensor chip and the integrated circuit and has a second incident window that allows infrared light to enter the sensor chip.   4. The infrared sensor according to claim 1, wherein the center of the lens is separated from a perpendicular passing through the centers of the plurality of light receiving elements toward the integrated circuit.

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