CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to and the benefit of Japanese Patent Application No. 2020-045669 filed Mar. 16, 2020 and Japanese Patent Application No. 2021-32049 filed Mar. 1, 2021, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a gas detection apparatus.

BACKGROUND

Gas detection apparatuses for detecting gases have been used in various fields. For example, PTL 1 discloses an apparatus including a light source for emitting infrared light and a detector for detecting infrared light in a certain wavelength, accommodated in the same case. A gas to be detected is introduced to the case.

CITATION LIST

Patent Literature

PTL 1: JP 2015-184211 A

SUMMARY

Here, the gas detection apparatus described in PTL 1 reflects light multiple times by a plurality of mirrors to lengthen the optical path. In this case, when a plurality of optical members are disposed in the optical system, an image of light received by a light receiving element may be altered from the original image due to a conversion, such as a magnification, reduction, or rotation, of the image of light emitted by a light emitting element, or influences of optical aberration and diffraction. Such alternations of the image of light may interfere with stable and highly accurate gas detections.

In the meantime, lamps have been used as light sources in gas detection apparatuses. In recent years (since 2018), however, surface mount device (SMD) type medium-infrared LED light sources have been developed and been in mass production, and light sources having significantly smaller light emitting elements than lamps have been used. In conventional lamps, the size of light incident on a light receiving element (cross-sectional area of an incident light flux) is sufficiently larger than the size of a light receiving element, and the cross-section of the incident light flux extends so as to form a rotationally symmetrical shape (typically forming a circular shape). In an LED light source, on the other hand, the cross-sectional area of an incident light flux is equal to or smaller than the size of a light receiving element. Because the shape of the light source is rectangular, the cross-section of the incident light flux has also a rectangular shape having corners. In this case, the corners of the cross-section of the incident light flux may be out of the light receiving element, which results in a reduced signal to noise ratio (SNR) of the light receiving element.

It would be thus helpful to provide a solution to the above-mentioned convention issue by providing stable and highly accurate gas detection apparatuses.

A gas detection apparatus according to an embodiment of the present disclosure comprises:

a light emitting element provided on a main surface of the substrate for emitting light from a light emitting surface;

a light receiving element provided on the main surface of the substrate for receiving the light on a light receiving surface; and

a light guide member for guiding the light emitted by the light emitting element to the light receiving element,

in plan view of the main surface of the substrate,the light emitting surface and the light receiving surface being shaped to have corners, andside of the light emitting surface after being subjected to a magnification or reduction and a translation not overlapping sides of the light receiving surface.

As used herein, the term “light emitting surface” refers to a surface which is in contact with the gas at a light emitting portion of an element and is made of an optically transparent material. The term “light receiving surface” refers to a surface which is in contact with the gas at a light sensitive portion of the element and is made from an optically transparent material.

A gas detection apparatus according to an embodiment of the present disclosure comprises:

a light emitting element provided on a main surface of the substrate for emitting light from a light emitting surface;

a light receiving element provided on the main surface of the substrate for receiving the light on a light receiving surface; and

a light guide member for guiding the light emitted by the light emitting element to the light receiving element,

in plan view of the main surface of the substrate,the light emitting surface and the light receiving surface being shaped to have corners, andsides of the light emitting surface being parallel to neither sides of the light receiving surface.

A gas detection apparatus according to an embodiment of the present disclosure comprises:

a substrate having a rectangular main surface;

a light emitting element provided on a main surface of the substrate for emitting light from a rectangular light emitting surface;

a light receiving element provided on the main surface of the substrate for receiving the light on a rectangular light receiving surface; and

a light guide member for guiding the light emitted by the light emitting element to the light receiving element,

sides of the light receiving surface or the light emitting surface being parallel to neither sides of the main surface of the substrate in the plan view of the main surface of the substrate.

According to one embodiment of the present disclosure, stable and highly accurate gas detections apparatuses can be provided.

