CN-122016588-A - Dust sensor for reducing stray light

Abstract

The invention relates to a dust sensor for reducing stray light, which comprises a shell, a light-emitting element, a light-receiving element and a circuit board, wherein the shell is provided with a partition wall which is divided into a circuit board area and a detection area, a dust passage is positioned in the detection area, the circuit board is arranged in the circuit board area, the partition plate is respectively provided with a light-emitting hole and a light-receiving hole corresponding to the light-emitting element and the light-receiving element, a gap is reserved between the light-emitting element and the light-emitting hole, the circuit board area is also provided with a light-shielding plate which vertically extends downwards from the shell corresponding to the light-emitting element, the light-receiving element is embedded in the light-receiving hole, two sides of the light-receiving element are provided with light-shielding walls which vertically penetrate through and are connected with the partition wall, and the end parts of the light-shielding walls extend towards the dust-passing holes. The invention can reduce stray light, but does not need lens, can reduce assembly cost and assembly difficulty, and improve assembly efficiency.

Inventors

• YOKOGAWA SEIICHI
• Zengtian Jiashi
• Bao Yuzao
• Gang Shunzhi
• Sato chinen
• ICHINOSE TOSHIYUKI

Assignees

• 缘成科技(河南)有限公司

Dates

Publication Date

20260512

Application Date

20250530

Claims (10)

1. 1. A dust sensor for reducing stray light comprises a shell, a light-emitting element, a light-receiving element and a circuit board, wherein a vertically penetrating partition wall is arranged in the shell, the inside of the shell is divided into a circuit board area and a detection area by the partition wall, dust through holes vertically penetrating are formed in the top surface and the bottom surface of the shell, a dust through channel is formed between the two dust through holes, the dust through channel is located in the detection area, the light-emitting element and the light-receiving element are surface-mounted on the circuit board and the optical axis passes through the dust through channel, the circuit board is mounted in the circuit board area, the partition plate is respectively provided with the light-emitting hole and the light-receiving hole corresponding to the light-emitting element and the light-receiving element, a gap is reserved between the light-emitting element and the light-emitting hole, the circuit board area is also provided with a light-shielding plate corresponding to the light-emitting element and extending vertically downwards from the shell, the light-receiving element is embedded in the light-receiving hole, the two sides of the light-receiving element are provided with vertically penetrating light-shielding walls connected with the partition wall, and the light-shielding wall extends towards the dust through holes.
2. 2. The dust sensor for reducing stray light according to claim 1, wherein a clip groove A corresponding to the light emitting element is provided at a lower end of the light shielding plate, and the light emitting element is fitted in the clip groove A.
3. 3. The dust sensor for reducing stray light according to claim 2, wherein the circuit board area is provided with a support plate extending vertically upward from the housing in correspondence with the light emitting element, the support plate supporting the circuit board on which the light emitting element is located.
4. 4. The dust sensor for reducing stray light according to claim 3, wherein the circuit board region is further provided with an upper clamping plate extending vertically downward from the housing and a lower clamping plate extending vertically upward from the housing, and the upper clamping plate and the lower clamping plate clamp the circuit board at the position of the light receiving element.
5. 5. The dust sensor for reducing stray light of claim 4 wherein there are two light receiving elements disposed symmetrically about the circuit board.
6. 6. The dust sensor for reducing stray light according to claim 1 or 5, wherein the housing comprises a cover body and a case body fastened up and down, the partition plate comprises an upper wall integrated with the cover body and a lower wall integrated with the case body, the partition wall is provided with a clamping groove matched with the edge of the circuit board, the upper edge of the clamping groove is arranged on the upper wall, the lower edge of the clamping groove is arranged on the lower wall, and the clamping groove clamps the edge of the circuit board.
7. 7. The dust sensor for reducing stray light of claim 6 wherein the upper plate is integral with the upper wall and the lower plate is integral with the lower wall.
8. 8. The dust sensor for reducing stray light according to claim 1, wherein sharp corners extending toward the dust hole are provided at edges of the detection area, light trapping portions are formed between adjacent sharp corners, and an angle between the adjacent sharp corners is not more than 30 °.
9. 9. The dust sensor for reducing stray light of claim 1 wherein the light emitting aperture is a horn structure facing the circuit board area.
10. 10. The dust sensor for reducing stray light according to claim 6, further comprising a connecting screw, wherein the cover is provided with an upper connecting post, the case is provided with a lower connecting post, a lower counter bore is formed in the upper connecting post, the lower connecting post is provided with a threaded hole, the connecting screw passes through the lower counter bore, the circuit board is in threaded connection with the threaded hole, the cover and the case are made of conductive resin, and the area of the circuit board through which the connecting screw passes is a grounding part of the circuit board.

Description

Dust sensor for reducing stray light Technical Field The invention relates to the technical field of dust sensors, in particular to a dust sensor capable of reducing stray light. Background The dust sensor is a sensor for dust particle concentration detection. The patent application 202010071929.9 has been summarized and summarized in comparison to existing optical dust sensors. In general, the optical dust sensor is provided with a light emitting element and a light receiving element. The light-emitting element emits projection light, and the projection light and dust particles scatter in the detection area to form scattered light. A part of the scattered light is directed to the light receiving element and received by the light receiving element. The light receiving element detects the part of the scattered light, and calculates the dust concentration from the light intensity decay. The patent also defines the concept of stray light, i.e., unwanted light that projects light into the light receiving element, as opposed to scattered light, and classifies stray light into two categories. The first type of stray light is projected light which is reflected and enters the light receiving element, and the second type of stray light is projected light which is directly enters the light receiving element. The patent explicitly proposes a measure for reducing the stray light interference by correcting or suppressing a measurement error caused by a pulse technique value of the stray light component. Besides, the measures for reducing stray light in the prior art further comprise arranging lenses on the light path of the light emitting element and the light path of the light receiving element, so that a plurality of parts are required to be assembled when the dust sensor is assembled, the assembly cost and the assembly difficulty are increased, and the assembly efficiency is reduced. Disclosure of Invention The present invention has been made to solve the above problems, and an object of the present invention is to provide a dust sensor that reduces stray light. The technical scheme includes that the dust sensor for reducing stray light comprises a shell, a light emitting element, a light receiving element and a circuit board, wherein a vertically penetrating separation wall is arranged in the shell, the inside of the shell is divided into a circuit board area and a detection area by the separation wall, dust through holes vertically penetrating through the top surface and the bottom surface of the shell are respectively formed in the top surface and the bottom surface of the shell, dust through channels are formed between the two dust through holes and used for enabling dust to pass through, the dust through channels are positioned in the detection area, the light emitting element and the light receiving element are arranged on the circuit board, the light emitting element and the light receiving element are respectively provided with a light emitting hole and a light receiving hole corresponding to the light emitting element and the light receiving element, and the dust sensor is characterized in that a gap is reserved between the light emitting element and the light emitting hole, a light shielding plate vertically extending downwards from the shell corresponding to the light emitting element is further arranged in the circuit board area, and some emitted light inclined to the optical axis of the light emitting element can directly penetrate onto the separation wall by utilizing the gap and then be reflected back to the light shielding plate, and the emitted light is further reflected at the light shielding plate. The light emitted by the optical axes of the inclined and luminous elements is limited in the circuit board area and attenuated by multiple reflections, the circuit board and the elements on the circuit board are shielded by the light shielding plate, the light receiving elements are embedded in the light receiving holes, the two sides of the light receiving elements in the detection area are provided with the light shielding walls which vertically penetrate and are connected with the separation walls to shield stray light entering the detection area, and the end parts of the light shielding walls extend to the dust passing holes to ensure that the light receiving elements are fully shielded. Preferably, the lower end of the light shielding plate is provided with a clamping groove A corresponding to the light emitting element, the light emitting element is embedded in the clamping groove A, and the clamping groove A carries out horizontal limiting on the light emitting element to ensure the stable installation position of the light emitting element. Furthermore, the circuit board area is provided with a supporting plate which corresponds to the light-emitting element and extends vertically upwards from the shell, the supporting plate supports the circuit board where the light-emitting element is located,