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US-12625006-B2 - Curved prism array applied to an infrared sensor

US12625006B2US 12625006 B2US12625006 B2US 12625006B2US-12625006-B2

Abstract

A curved prism array applied to an infrared sensor wherein: the infrared sensor comprises at least an infrared sensing element which is used in detecting infrared signals within a solid-angled FOV and installed inside the curved prism array; the curved prism array has an incident focal plane and a plurality of emergent focal planes, both of which are not parallel with each other, such that infrared signals beyond the solid-angled FOV are received by the incident focal plane, refracted through one of the emergent focal planes and guided toward the infrared sensing element for expansion of the solid-angled FOV of the infrared sensing element.

Inventors

  • Wen-Chin Chen
  • Ai-Huan LEE

Assignees

  • SENSORLITE INC.

Dates

Publication Date
20260512
Application Date
20220915

Claims (8)

  1. 1 . A curved prism array applied to an infrared sensor which comprises at least an infrared sensing element which is used in detecting infrared signals within a solid-angled FOV and installed inside the curved prism array, wherein the curved prism array comprises: an incident focal plane; and a plurality of emergent focal planes facing toward the infrared sensing element, wherein each of the emergent focal planes and the incident focal plane, both of which form an optical focusing structure with an uneven thickness, are not parallel to each other such that the infrared sensing element features an expanded solid-angled FOV; the incident focal plane contacted by an incident infrared ray beyond the solid-angled FOV refracts the incident infrared ray, which is subject to a focusing direction of the incident focal plane, at a specific angle such that an internal infrared ray entering a space between the incident focal plane and an emergent focal plane is guided to the emergent focal plane and further refracted at another specific angle under the effect of a focusing direction of the emergent focal plane for development of an emergent infrared ray that emits toward the infrared sensing element for an expanded solid-angled FOV of the infrared sensing element, wherein each of the emergent focal planes has a first endpoint and a second endpoint, both of which are opposite to the incident focal plane, and a distance from the first endpoint to the incident focal plane is greater than another distance from the second endpoint to the incident focal plane such that the emergent focal plane and the incident focal plane are not parallel to each other, and wherein a thickness from the second endpoint to the incident focal plane is greater than 0.25 mm.
  2. 2 . The curved prism array applied to an infrared sensor as claimed in claim 1 , wherein each of the emergent focal planes created in a cutting process is an optical surface through which infrared rays are focused within a solid-angled FOV of the infrared sensing element.
  3. 3 . The curved prism array applied to an infrared sensor as claimed in claim 1 , wherein the solid-angled FOV comprises a vertical field of view and a horizontal field of view.
  4. 4 . The curved prism array applied to an infrared sensor as claimed in claim 1 , wherein a thickness from the first endpoint to the incident focal plane is less than 1.2 mm.
  5. 5 . The curved prism array applied to an infrared sensor as claimed in claim 1 , wherein the incident focal plane is either a curved surface or a planar surface.
  6. 6 . The curved prism array applied to an infrared sensor as claimed in claim 1 , wherein the emergent focal plane is either a curved surface or a planar surface.
  7. 7 . The curved prism array applied to an infrared sensor as claimed in claim 1 , wherein incident infrared rays for the same detection point are parallel to one another and emergent infrared rays refracted through different emergent focal planes are focused within a vertical field of view of the infrared sensing element for enhancing signal gain of an identical detection distance.
  8. 8 . The curved prism array applied to an infrared sensor as claimed in claim 1 , wherein the infrared sensing element is a pyroelectric infrared sensing element.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present application relates to a curved prism array applied to an infrared sensor, particularly a curved prism array with which a solid-angled FOV (field of view) of an infrared sensor is expanded. 2. Description of Related Art Based on a difference between human temperature and ambient temperature, a general pyroelectric infrared sensing element which features a set of optical lenses made of high density polyethylene (HDPE) (for example, lenses, prisms or mirror planes) focuses human temperature-induced infrared rays with wavelengths ranging from 5 to 14 μm and project infrared radiation from human temperature on an embedded sensing element precisely for sensing human temperature of a person moving within a specific area. In general, an infrared sensor is internally equipped with an optical element through which infrared radiation is focused and precisely projected on a sensing element mounted inside the infrared sensor. As shown in U.S. Pat. Nos. 4,268,752, 6,653,635 and 4,271,360, an ordinary infrared sensing element is equipped with an infrared filtration window through which infrared rays with wavelengths beyond 5-14 um are filtered out but criticized for a vertical field of view restricted by the dimensions of the filtration window. For expansion of the vertical field of view of an infrared sensor, a signal reflector installed correspondingly is used in focusing incident rays outside the vertical field of view of the infrared sensor on different focal points for projection of incident rays on the infrared sensing element. The above design, however, is criticized for drawbacks like complicated structure, oversize, increased costs for materials and machining, and assembly and deserves to be corrected in other solutions. Accordingly, a curved prism array for expansion of the solid-angled FOV of an infrared sensor is designed in the present application. For the application in an infrared sensor, the curved prism array, which is able to expand the solid-angled FOV of an infrared sensing element inside the infrared sensor and detect infrared signals beyond the solid-angled FOV, can be regarded as a good solution. SUMMARY OF THE INVENTION The present disclosure relates to a curved prism array applied to an infrared sensor. The infrared sensor comprises at least an infrared sensing element which is used in detecting infrared signals within a solid-angled FOV and installed inside the curved prism array wherein: the curved prism array has an incident focal plane and a plurality of emergent focal planes facing toward the infrared sensing element; each of the emergent focal planes and the incident focal plane, both of which form an optical focusing structure with an uneven thickness, are not parallel to each other such that the infrared sensing element features an expanded solid-angled FOV; the incident focal plane contacted by an incident infrared ray beyond the solid-angled FOV refracts the incident infrared ray, which is subject to a focusing direction of the incident focal plane, at a specific angle such that an internal infrared ray entering a space between the incident focal plane and an emergent focal plane is guided to the emergent focal plane and further refracted at another specific angle under the effect of a focusing direction of the emergent focal plane for development of an emergent infrared ray that emits toward the infrared sensing element for an expanded solid-angled FOV of the infrared sensing element. Specifically, each of the emergent focal planes created in a cutting process is an optical surface through which infrared rays are focused within a solid-angled FOV of the infrared sensing element. Specifically, the solid-angled FOV comprises a vertical field of view and a horizontal field of view. Specifically, each of the emergent focal planes has a first endpoint and a second endpoint, both of which are opposite to the incident focal plane, wherein a distance from the first endpoint to the incident focal plane is greater than another distance from the second endpoint to the incident focal plane such that the emergent focal plane and the incident focal plane are not parallel to each other. Specifically, a thickness from the first endpoint to the incident focal plane is less than 1.2 mm. Specifically, a thickness from the second endpoint to the incident focal plane is greater than 0.25 mm. Specifically, the incident focal plane is either a curved surface or a planar surface. Specifically, the emergent focal plane is either a curved surface or a planar surface. Specifically, incident infrared rays for the same detection point are parallel to one another and emergent infrared rays refracted through different emergent focal planes are focused within a vertical field of view of the infrared sensing element for enhancing signal gain of an identical detection distance. Specifically, the infrared sensing element is a pyroelectric infrared sensing