Miniature packaged laser gas sensor and preparation method thereof

Abstract

The invention provides a miniature packaged laser gas sensor and a preparation method, the sensor comprises a cover piece, an upper shell and a lower shell, and a miniature gas chamber is arranged in the upper shell; a signal circuit board is arranged at the bottom of the lower shell; a first lens, a second lens, a laser emitting unit and a light receiving unit are arranged in the micro air chamber; the laser emitting unit and the light receiving unit are respectively connected with the signal circuit board; light emitted by the laser emitting unit passes through the first lens and then enters the miniature gas chamber, then passes through the second lens and is received by the light receiving unit, a light signal is obtained, and the signal circuit board finally converts the light signal into gas concentration information. The laser gas sensor has the beneficial effects that the laser gas sensor adopts a non-TO packaging structure, so that the integration level of the sensor is improved, the size is smaller, the surface-mounted or direct-insertion type pins are arranged, secondary integration of the sensor is facilitated, a surface mounting process is adopted for preparation of the sensor, stable batch production is easier, and the cost is lower.

Description

Technical Field

[0001] The present invention relates to the technical field of gas detection, and in particular to a micro-packaged laser gas sensor and a preparation method thereof. Background Art

[0002] Gas detection technology based on tunable diode laser absorption spectroscopy (TDLAS) has the advantages of high sensitivity, strong anti-interference ability, fast response speed, and real-time detection. Therefore, this technology has broad application prospects. TDLAS laser gas sensors generally include a light emitting unit, a light receiving unit, an absorption gas chamber, and an information processing unit. Existing laser gas sensors generally have problems such as large size, complex packaging process, and high production cost. In this regard, different manufacturers have also proposed some improvement plans. For example, Hanwei Technology proposed a laser methane sensor based on a V-shaped optical path in patent CN221707276U. The V-shaped optical path is constructed using an integrated V-shaped profile, which ensures the accuracy of the optical path components. At the same time, the installation holes for the transmitting laser and the receiving detector are reserved, which effectively ensures the high accuracy of the optical path setting, greatly reduces the difficulty of manual adjustment, and reduces the overall volume of the sensor to a certain extent. Wuhan Liujiu Sensor proposed a photoelectric gas sensor in patent CN104568831B from the perspective of integrated sensor packaging. The laser source and detector are encapsulated in an integrated optical transceiver, and the integrated optical transceiver is placed inside the gas chamber structure. The laser light emitted from the laser source is coupled to the detector through the optical path structure, which is conducive to the miniaturization of the equipment. However, in the production and manufacturing process of the sensor of the above scheme, the laser light source and the detector chip of the laser gas sensor need to be independently packaged using the TO packaging process before being combined to form a sensor. Moreover, the TO packaging process is often incompatible with the production and manufacturing process of the sensor, making the process complicated. All of these have greatly restricted the miniaturization and high-efficiency mass production of the sensor. In addition, for some special application scenarios, the sensor is also required to be integrated for secondary use in the alarm or gas analyzer, which places higher requirements on the integrated design of the sensor. Summary of the Invention

[0003] In view of this, the present invention provides a micro-packaged laser gas sensor, comprising a cover, an upper shell and a lower shell, wherein the cover is arranged on the top of the upper shell, and the lower shell is connected to the bottom of the upper shell; The upper shell is provided with a hollow cavity, so that the cover, the upper shell and the lower shell are combined to form a micro air chamber; the cover can allow the ambient gas to be measured to enter and exit the micro air chamber; The upper shell is further provided with a first accommodating groove and a second accommodating groove; The lower shell is provided with a first air-avoiding hole and a second air-avoiding hole, and a signal circuit board is provided at the bottom of the lower shell; A first lens is installed in the first accommodating groove, and a second lens is installed in the second accommodating groove. The first accommodating groove and the second accommodating groove respectively form a first sealed cavity and a second sealed cavity with the first air avoidance hole, the second air avoidance hole and the signal circuit board; a laser emitting unit is provided in the first sealed cavity, and a light receiving unit is provided in the second sealed cavity. The laser emitting unit and the light receiving unit are respectively connected to the signal circuit board; the light emitted by the laser emitting unit enters the micro gas chamber after passing through the first lens, and then passes through the second lens to be received by the light receiving unit and obtain an optical signal. The signal circuit board finally converts the optical signal into gas concentration information.

[0004] Furthermore, the signal circuit board is provided with at least one reflective member, the upper shell also includes at least one third accommodating groove, the lower shell is provided with at least one third air avoidance hole corresponding to the at least one third accommodating groove, and the at least one reflective member is arranged to pass through the at least one third air avoidance hole and the at least one third accommodating groove in sequence.

[0005] Furthermore, the light emitted by the laser emitting unit is reflected by the at least one reflector and is finally received by the light receiving unit.

[0006] Furthermore, the at least one reflective element is a reflector or a non-mirror reflective element.

[0007] Furthermore, a first heating element is provided in the at least one third air-avoiding hole, and the first heating element is electrically connected to the signal circuit board and is used to control the surface temperature of the at least one reflective element.

[0008] Furthermore, the laser emitting unit includes a laser chip and a temperature control component, the laser chip is electrically connected to the signal circuit board, and the temperature control component is used to adjust the temperature in the first sealed cavity; the light receiving unit includes a detector chip and a second heating element, the detector chip is electrically connected to the signal circuit board, and the second heating element is used to adjust the temperature in the second sealed cavity.

[0009] Furthermore, the signal circuit board is also provided with a plurality of signal pins, and the signal pins are surface-mount L-shaped pins or straight-insert pin pins.

[0010] Furthermore, the first lens is a hemispherical lens, which is used to convert the laser beam emitted by the light emitting unit into parallel light; the second lens is a spherical lens, which is used to converge the laser beam irradiated thereon to the detector chip.

[0011] Furthermore, the cover is a waterproof and breathable membrane; and the first sealed cavity and / or the second sealed cavity is filled with an inert gas.

[0012] The present invention also provides a method for preparing a micro-encapsulated laser gas sensor, which is used to prepare the above-mentioned micro-encapsulated laser gas sensor, comprising the following steps: S1: Integrate a laser emitting unit, a light receiving unit, and a signal pin on the signal circuit board; wrap the signal circuit board with molten raw material, and use an injection molding process to prepare the lower shell, wherein the lower shell is provided with a first air avoidance hole and a second air avoidance hole; and use an injection molding process to prepare the upper shell, wherein the upper shell is provided with a first receiving groove and a second receiving groove; S2 bonding the first lens and the second lens to the set positions of the first receiving groove and the second receiving groove respectively through a gluing process; S3: preparing a cover capable of air intake and air exhaust, and sequentially attaching the cover, the upper shell, and the lower shell using a surface mount process to obtain the micro-packaged laser gas sensor.

[0013] Furthermore, in step S1, the lower shell also includes at least one third air avoidance hole formed by injection molding, and the upper shell also includes at least one third accommodating groove formed by injection molding and corresponding to the at least one third air avoidance hole, and at least one reflector and at least one first heating element are fixed at the set position of the at least one third air avoidance hole.

[0014] Furthermore, in step S2, a step of filling the first sealed cavity and / or the second sealed cavity with an inert gas is also included.

[0015] Compared with the prior art, the micro-packaged laser gas sensor of the present invention has the following advantages: 1) The light emitting unit and light receiving unit of the gas sensor of the present invention abandon the traditional TO package (that is, the previous laser is packaged by a laser chip, TEC, a gasket, a thermistor, a hemispherical lens or a window piece, a tube cap, a tube seat and metal leads, and the detector also needs to be packaged by a detection chip, a gasket, a heating resistor, a lens, a tube cap, a tube seat and metal leads). The light emitting unit and the light receiving unit are directly connected to the signal circuit board, so that the light emitting unit and the light receiving unit directly form the first and second sealed cavities with the upper and lower shells. This not only plays the role of the traditional TO package, but also improves the sensor integration and makes it smaller (saving the laser diode, the tube cap, the tube seat, the metal leads and other components of the detector, which greatly saves costs), so that the gas to be measured can quickly enter the measurement cavity for detection, thereby improving the response time.

[0016] 2) The sensor structure of the laser gas sensor of the present invention adopts a chip-like design and uses surface mount or direct plug-in pins, which facilitates secondary integration of the user's device and the entire machine.

[0017] 3) The laser gas sensor of the present invention adopts a plastic shell as a whole, which has strong corrosion resistance and is easy to manufacture. In addition, the preparation method of the micro-packaged laser gas sensor of the present invention adopts surface mounting technology as a whole. Compared with the traditional method of independently TO-packaging the laser and the detector and then combining them to manufacture a laser gas sensor, it is easier to stably mass-produce and has lower cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a cross-sectional view of a micro-packaged laser gas sensor according to an embodiment of the present invention; Figure 2 1 is a top view of an upper housing of a micro-packaged laser gas sensor according to an embodiment of the present invention; Figure 3 is a cross-sectional view of an upper housing of a micro-packaged laser gas sensor according to an embodiment of the present invention; Figure 4 This is an exploded view of a micro-packaged laser gas sensor according to an embodiment of the present invention; Figure 5 is a three-dimensional structural diagram of another embodiment of a micro-packaged laser gas sensor of the present invention; In the above figure: 1-second sealed cavity, 2-first sealed cavity, 3-laser emitting unit, 4-temperature controller, 5-detector chip, 6-third heating element, 7-first lens, 8-second lens, 9-reflecting element, 10-signal pin, 11-micro air chamber, 12-signal circuit board, 13-first heating element, 14-second heating element, 15-third accommodating groove, 100-cover, 200-upper shell, 300-lower shell. DETAILED DESCRIPTION

[0019] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0020] refer to Figures 1 to 4 The micro-packaged laser gas sensor of the embodiment of the present invention includes a cover 100, an upper shell 200 and a lower shell 300, wherein the cover 100 is provided on the top of the upper shell 200, and the lower shell 300 is connected to the bottom of the upper shell 200; The upper housing 200 is provided with a hollow cavity, so that the cover 100, the upper housing 200 and the lower housing 300 are combined to form a micro air chamber 11; the cover 100 allows the ambient gas to enter and exit the micro air chamber 11; The upper housing 200 is further provided with a first receiving groove and a second receiving groove; The lower housing 300 is provided with a first air-avoiding hole and a second air-avoiding hole, and a signal circuit board 12 is provided at the bottom of the lower housing 300; A first lens 7 is installed in the first accommodating groove, and a second lens 8 is installed in the second accommodating groove. The first accommodating groove and the second accommodating groove respectively form a first sealed cavity and a second sealed cavity 1 with the first air avoidance hole, the second air avoidance hole and the signal circuit board 12; a laser emitting unit 3 is provided in the first sealed cavity 2, and a light receiving unit is provided in the second sealed cavity 1. The laser emitting unit 3 and the light receiving unit are respectively connected to the signal circuit board 12; the light emitted by the laser emitting unit 3 enters the micro gas chamber 11 after passing through the first lens 7, and then passes through the second lens 8 to be received by the light receiving unit and obtain an optical signal. The signal circuit board 12 finally converts the optical signal into gas concentration information.

[0021] In a preferred embodiment, at least one reflector 9 is provided on the signal circuit board 12, the upper housing 200 further includes at least one third receiving slot 15, and the lower housing 300 is provided with at least one third air-avoidance hole corresponding to the at least one third receiving slot 15. The at least one reflector 9 is sequentially arranged to pass through the at least one third air-avoidance hole and the at least one third receiving slot 15. Light emitted by the laser emitting unit 3 is reflected by the at least one reflector 9 and ultimately received by the light receiving unit.

[0022] It is understood that there can be one or more reflective members 9, which are used to reflect the light emitted by the laser emitting unit 3, thereby extending the light path. When there is one reflective member 9, the light emitted by the laser emitting unit 3 is ultimately reflected into a V-shape; when there are two reflective members 9, the light emitted by the laser emitting unit 3 is ultimately reflected into a Z-shape. The reflective member 9 can be a mirror or a non-mirror reflective member 9.

[0023] In a preferred embodiment, a first heating element 13 is provided in the at least one third air-avoiding hole. The first heating element 13 is electrically connected to the signal circuit board 12 and is used to control the surface temperature of the at least one reflector 9. The first heating element 13 can be a heating resistor.

[0024] In a preferred embodiment, the laser emitting unit 3 includes a laser chip and a temperature control component, the laser chip is electrically connected to the signal circuit board 12, the temperature control component includes a temperature controller 4 and a third heating element 6, and the temperature control component is used to adjust the temperature in the first sealed cavity 2; the light receiving unit includes a detector chip 5 and a second heating element 14, the detector chip 5 is electrically connected to the signal circuit board 12, and the second heating element 14 is used to adjust the temperature in the second sealed cavity 1.

[0025] In a preferred embodiment, the first lens 7 is a hemispherical lens, which is used to convert the laser beam emitted by the light emitting unit into parallel light; the second lens 8 is a spherical lens, which is used to converge the laser beam irradiated thereon to the detector chip 5.

[0026] In a preferred embodiment, the cover 100 is a waterproof and breathable membrane; and the first sealed cavity 2 and / or the second sealed cavity 1 is filled with an inert gas.

[0027] In a preferred embodiment, the signal circuit board 12 is further provided with a plurality of signal pins 10 , and the signal pins are surface-mount L-shaped pins.

[0028] refer to Figure 5 In another embodiment of this embodiment, the signal pins 10 are 8 straight-insertion pins, and the pins are led out from the bottom surface of the lower shell 300.

[0029] The present invention also provides a method for preparing a micro-encapsulated laser gas sensor, which is used to prepare the above-mentioned micro-encapsulated laser gas sensor, and the method comprises the following steps: S1: Integrate the laser emitting unit 3, the light receiving unit, and the signal pin 10 on the signal circuit board 12; Wrap the signal circuit board 12 with molten raw material, and use an injection molding process to prepare the lower shell 300, wherein the lower shell 300 is provided with a first air avoidance hole and a second air avoidance hole; Use an injection molding process to prepare the upper shell 200, wherein the upper shell 200 is provided with a first receiving groove and a second receiving groove; S2: bonding the first lens 7 and the second lens 8 to the set positions of the first receiving groove and the second receiving groove respectively through a gluing process; S3: Prepare a cover 100 capable of air intake and air exhaust, and sequentially attach the cover 100, the upper shell 200, and the lower shell 300 using a surface mount process to obtain the micro-packaged laser gas sensor.

[0030] In a preferred embodiment, in step S1, the lower shell 300 also includes at least one third air avoidance hole formed by injection molding, and the upper shell 200 also includes at least one third accommodating groove formed by injection molding and corresponding to the at least one third air avoidance hole, and at least one reflector 9 and at least one first heating element 13 are fixed at the set position of the at least one third air avoidance hole.

[0031] In a preferred embodiment, step S2 further includes a step of filling the first sealed cavity and / or the second sealed cavity with an inert gas.

[0032] The preparation method of the micro-packaged laser gas sensor of the present invention adopts surface mount technology as a whole. Compared with the traditional method of independently TO-packaging the laser and the detector and then combining them to manufacture the laser gas sensor, it is easier to stably mass-produce and has lower cost.

[0033] In this document, directional terms such as front, back, top, and bottom are defined based on the positions of components in the accompanying drawings and relative to each other, and are intended only for clarity and convenience in describing the technical solution. It should be understood that the use of these directional terms should not limit the scope of protection claimed in this application.

[0034] In the absence of conflict, the above embodiments and features in the embodiments may be combined with each other.

[0035] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A micro-packaged laser gas sensor, characterized in that: The device comprises a cover, an upper shell and a lower shell, wherein the cover is arranged on the top of the upper shell, and the lower shell is connected to the bottom of the upper shell; The upper shell is provided with a hollow cavity, so that the cover, the upper shell and the lower shell are combined to form a micro air chamber; the cover can allow the ambient gas to be measured to enter and exit the micro air chamber; The upper shell is further provided with a first accommodating groove and a second accommodating groove; The lower shell is provided with a first air-avoiding hole and a second air-avoiding hole, and a signal circuit board is provided at the bottom of the lower shell; A first lens is installed in the first accommodating groove, and a second lens is installed in the second accommodating groove. The first accommodating groove and the second accommodating groove respectively form a first sealed cavity and a second sealed cavity with the first air avoidance hole, the second air avoidance hole and the signal circuit board; a laser emitting unit is provided in the first sealed cavity, and a light receiving unit is provided in the second sealed cavity. The laser emitting unit and the light receiving unit are respectively connected to the signal circuit board; the light emitted by the laser emitting unit enters the micro gas chamber after passing through the first lens, and then passes through the second lens to be received by the light receiving unit and obtain an optical signal. The signal circuit board finally converts the optical signal into gas concentration information.

2. A micro-packaged laser gas sensor according to claim 1, characterized in that: At least one reflective member is provided on the signal circuit board, the upper shell further includes at least one third accommodating groove, the lower shell is provided with at least one third avoidance hole corresponding to the at least one third accommodating groove, and the at least one reflective member is arranged to pass through the at least one third avoidance hole and the at least one third accommodating groove in sequence.

3. A micro-packaged laser gas sensor according to claim 2, characterized in that: The light emitted by the laser emitting unit is reflected by the at least one reflector and is finally received by the light receiving unit.

4. A micro-packaged laser gas sensor according to claim 3, characterized in that: The at least one reflective element is a reflector or a non-mirror reflective element.

5. The micro-packaged laser gas sensor according to claim 2, characterized in that: A first heating element is provided in the at least one third air-avoiding hole. The first heating element is electrically connected to the signal circuit board and is used to control the surface temperature of the at least one reflective element.

6. A micro-packaged laser gas sensor according to any one of claims 1 to 5, characterized in that: The laser emitting unit includes a laser chip and a temperature control component, the laser chip is electrically connected to the signal circuit board, and the temperature control component is used to adjust the temperature in the first sealed cavity; the light receiving unit includes a detector chip and a second heating element, the detector chip is electrically connected to the signal circuit board, and the second heating element is used to adjust the temperature in the second sealed cavity.

7. A micro-packaged laser gas sensor according to claim 6, characterized in that: The signal circuit board is further provided with a plurality of signal pins, and the signal pins are surface mount type L-shaped pins or direct plug-in pins.

8. The micro-packaged laser gas sensor according to claim 1, characterized in that: The first lens is a hemispherical lens, and the first lens is used to convert the laser beam emitted by the light emitting unit into parallel light; the second lens is a spherical lens, and the second lens is used to converge the laser beam irradiated thereon to the detector chip.

9. The micro-packaged laser gas sensor according to claim 1, characterized in that: The cover is a waterproof and breathable membrane; and the first sealed cavity and / or the second sealed cavity are filled with inert gas.

10. A method for preparing a micro-packaged laser gas sensor, the method being used to prepare the micro-packaged laser gas sensor according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1: Integrate a laser emitting unit, a light receiving unit, and a signal pin on the signal circuit board; wrap the signal circuit board with molten raw material, and use an injection molding process to prepare the lower shell, wherein the lower shell is provided with a first air avoidance hole and a second air avoidance hole; and use an injection molding process to prepare the upper shell, wherein the upper shell is provided with a first receiving groove and a second receiving groove; S2 bonding the first lens and the second lens to the set positions of the first receiving groove and the second receiving groove respectively through a gluing process; S3: preparing a cover capable of air intake and air exhaust, and sequentially attaching the cover, the upper shell, and the lower shell using a surface mount process to obtain the micro-packaged laser gas sensor.

11. The method for preparing a micro-packaged laser gas sensor according to claim 10, characterized in that: In step S1, the lower shell also includes at least one third air avoidance hole formed by injection molding, and the upper shell also includes at least one third accommodating groove formed by injection molding and corresponding to the at least one third air avoidance hole, and at least one reflector and at least one first heating element are fixed at the set position of the at least one third air avoidance hole.

12. The method for preparing a micro-packaged laser gas sensor according to claim 10, characterized in that: In step S2, the method further includes filling the first sealed cavity and / or the second sealed cavity with an inert gas.

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