CN112082624A - Liquid level detection device and detection method thereof - Google Patents
Liquid level detection device and detection method thereof Download PDFInfo
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- CN112082624A CN112082624A CN202010934195.2A CN202010934195A CN112082624A CN 112082624 A CN112082624 A CN 112082624A CN 202010934195 A CN202010934195 A CN 202010934195A CN 112082624 A CN112082624 A CN 112082624A
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- 239000007788 liquid Substances 0.000 title claims abstract description 196
- 238000001514 detection method Methods 0.000 title claims abstract description 165
- 239000000758 substrate Substances 0.000 claims abstract description 118
- 238000005259 measurement Methods 0.000 claims description 15
- 238000006243 chemical reaction Methods 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 4
- 229910052594 sapphire Inorganic materials 0.000 claims description 4
- 239000010980 sapphire Substances 0.000 claims description 4
- 229910052710 silicon Inorganic materials 0.000 claims description 3
- 239000010703 silicon Substances 0.000 claims description 3
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 3
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 3
- 230000010354 integration Effects 0.000 abstract description 10
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- 229910002601 GaN Inorganic materials 0.000 description 2
- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 238000004806 packaging method and process Methods 0.000 description 2
- 206010034960 Photophobia Diseases 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
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- 238000005516 engineering process Methods 0.000 description 1
- 238000009459 flexible packaging Methods 0.000 description 1
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- 230000001678 irradiating effect Effects 0.000 description 1
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- 239000003921 oil Substances 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 230000008707 rearrangement Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000012780 transparent material Substances 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
- G01F23/28—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring the variations of parameters of electromagnetic or acoustic waves applied directly to the liquid or fluent solid material
- G01F23/284—Electromagnetic waves
- G01F23/292—Light, e.g. infrared or ultraviolet
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
- G01N21/43—Refractivity; Phase-affecting properties, e.g. optical path length by measuring critical angle
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Abstract
The invention discloses a liquid level detection device and a detection method thereof, wherein the liquid level detection device comprises: a transparent substrate; the light emitting diode is arranged on the first side of the transparent substrate and used for emitting detection light; the photodiode is arranged on the first side of the transparent substrate and used for receiving the detection light reflected by the surface of the second side of the transparent substrate; wherein a first interface is formed between the second side surface of the transparent substrate and air; the first interface presents a first critical angle; the incident angle of the detection light ray on the second side surface of the transparent substrate is larger than the first critical angle. The technical scheme provided by the invention aims to solve the problems of larger volume and lower integration level of the conventional liquid level detection device.
Description
Technical Field
The invention relates to the technical field of semiconductors, in particular to a liquid level detection device and a detection method thereof.
Background
The existing liquid level photoelectric detector has multiple manufacturing modes, the principle is good, most of the existing liquid level photoelectric detectors adopt the detection modes that the transmitting tube and the receiving tube appear in pairs to detect, the transmitting tube can emit detection light, the detection light reaches the receiving tube through liquid refraction or reflection, and the detection light received by the receiving tube can change when being compared with the detection light which does not reach the receiving tube through liquid, so that the purpose of detecting the liquid level of the liquid is achieved.
However, in the prior art, the liquid level photoelectric detector needs to seal the transmitting tube, the receiving tube and the prism for reflecting the detection light into an integral device, and the integral device has larger volume and lower integration level and is not suitable for measuring the liquid level in small-sized equipment.
Disclosure of Invention
The embodiment of the invention provides a liquid level detection device and a detection method thereof, and aims to solve the problems of large volume and low integration level of the conventional liquid level detection device.
In a first aspect, an embodiment of the present invention provides a liquid level detection apparatus, including: a transparent substrate;
the light emitting diode is arranged on the first side of the transparent substrate and used for emitting detection light;
the photodiode is arranged on the first side of the transparent substrate and used for receiving the detection light reflected by the surface of the second side of the transparent substrate;
wherein a first interface is formed between the second side surface of the transparent substrate and air; the first interface presents a first critical angle; the incident angle of the detection light ray on the second side surface of the transparent substrate is larger than the first critical angle.
In a second aspect, an embodiment of the present invention further provides a liquid level detection method, which is applicable to the liquid level detection method provided in any embodiment of the present invention, and includes:
placing the liquid level detection device in an air environment, controlling the light emitting diode to emit detection light, enabling the photodiode to receive the detection light totally reflected by a first interface between the second side surface of the transparent substrate and the air, and recording a first current value formed by the photodiode;
placing the transparent substrate of the liquid level detection device in a liquid measurement environment to be measured, controlling the light emitting diode to emit detection light, enabling the photodiode to receive the detection light reflected by the second side surface of the transparent substrate, and recording a second current value formed by the photodiode;
and if the difference value between the first current value and the second current value is greater than a first set threshold value, judging that the liquid level of the liquid to be detected reaches the position of the liquid level detection device.
In the invention, the liquid level detection device comprises a light-emitting diode and a photodiode which are formed on the first side of the same transparent substrate, the light-emitting diode can emit detection light, the photodiode can receive the detection light reflected by the surface of one side (the second side) of the transparent substrate far away from the light-emitting diode, a first interface is formed between the surface of the second side of the transparent substrate and air, and the first interface has a first critical angle, the setting distance between the light-emitting diode and the photodiode is controlled in the embodiment, so that the incident angle of the detection light on the surface of the second side of the transparent substrate is larger than the first critical angle, the detection light is incident into the photodiode through total reflection in an air environment, the photocurrent generated by the photodiode is larger, and when the surface of the second side of the transparent substrate is liquid to be detected, the light path of the detection light is influenced not to be in a total, then the photocurrent that photodiode produced diminishes, judge the liquid level of the liquid that awaits measuring from this, in this embodiment, emitting diode and photodiode have been integrated simultaneously on liquid level detection device's the same substrate, the integration level is higher, for the scheme of integrated independent emitting diode component and photodiode in the same device, effectively reduce liquid level detection device's overall dimension, save the cost of manufacture, can be applicable to large-scale equipment and small-size equipment simultaneously, improve liquid level detection device's suitability, furthermore, the substrate is transparent substrate, can regard as the reflection interface who detects light, need not install the prism in addition additional, further reduced liquid level detection device's volume, the integration level is improved.
Drawings
FIG. 1 is a schematic structural diagram of a liquid level detecting device according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a total reflection phenomenon provided by an embodiment of the present invention;
FIG. 3 is a schematic structural diagram of a liquid level detection device located in an air environment according to an embodiment of the present invention;
FIG. 4 is a schematic structural diagram of a liquid level detection apparatus located in a liquid environment to be detected according to an embodiment of the present invention;
FIG. 5 is a schematic structural diagram of another liquid level detection apparatus provided by an embodiment of the present invention;
FIG. 6 is a schematic flow chart illustrating a method for detecting a liquid level according to an embodiment of the present invention;
FIG. 7 is a schematic structural diagram of a liquid level detection apparatus in a measurement environment of a liquid to be measured according to an embodiment of the present invention;
FIG. 8 is a schematic structural diagram of another liquid level detection apparatus provided in an environment for measuring a liquid to be measured according to an embodiment of the present invention;
FIG. 9 is a schematic structural diagram of another liquid level detection apparatus in a liquid measurement environment to be measured according to an embodiment of the present invention;
fig. 10 is a schematic structural diagram of a liquid level detection device in a microfluidic measurement environment according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
An embodiment of the present invention provides a liquid level detection apparatus, including: a transparent substrate;
the light emitting diode is arranged on the first side of the transparent substrate and used for emitting detection light;
the photodiode is arranged on the first side of the transparent substrate and used for receiving the detection light reflected by the surface of the second side of the transparent substrate;
wherein a first interface is formed between the second side surface of the transparent substrate and air; the first interface presents a first critical angle; the incident angle of the detection light on the second side surface of the transparent substrate is larger than the first critical angle.
It should be noted that the interface formed between the second side surface of the transparent substrate and the air is a first interface, and if the second side surface of the transparent substrate is in contact with other environments, such as liquid, solid, etc., the interface between the second side surface of the transparent substrate and the other environments is not the first interface, for example, the interface between the second side surface of the transparent substrate and the liquid to be measured is a second interface, each interface corresponds to a critical angle, and the first critical angle is a critical angle in the air environment, at which the liquid level detection device has not measured the liquid to be measured.
In the embodiment of the invention, the liquid level detection device comprises a light emitting diode and a photodiode which are formed on the first side of the same transparent substrate, the light emitting diode can emit detection light, the photodiode can receive the detection light reflected by the surface of one side (the second side) of the transparent substrate far away from the light emitting diode, a first interface is formed between the surface of the second side of the transparent substrate and air, and the first interface has a first critical angle, the setting distance between the light emitting diode and the photodiode is controlled in the embodiment, so that the incident angle of the detection light on the surface of the second side of the transparent substrate is larger than the first critical angle, the detection light is incident into the photodiode through total reflection in the air environment, the photocurrent generated by the photodiode is larger, and when the surface of the second side of the transparent substrate is liquid to be detected, the light path of the detection light is influenced not to be in a total reflection state, then the photocurrent that photodiode produced diminishes, judge the liquid level of the liquid that awaits measuring from this, in this embodiment, emitting diode and photodiode have been integrated simultaneously on liquid level detection device's the same substrate, the integration level is higher, for the scheme of integrated independent emitting diode component and photodiode in the same device, effectively reduce liquid level detection device's overall dimension, save the cost of manufacture, can be applicable to large-scale equipment and small-size equipment simultaneously, improve liquid level detection device's suitability, furthermore, the substrate is transparent substrate, can regard as the reflection interface who detects light, need not install the prism in addition additional, further reduced liquid level detection device's volume, the integration level is improved.
The above is the core idea of the present invention, and the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without any creative work belong to the protection scope of the present invention.
Fig. 1 is a schematic structural diagram of a liquid level detection device according to an embodiment of the present invention, as shown in fig. 1, the liquid level detection device includes a transparent substrate 11, a light emitting diode 12 and a photodiode 13 are simultaneously integrated on the transparent substrate 11, the transparent substrate 11 includes a first side and a second side opposite to each other, the light emitting diode 12 and the photodiode 13 are simultaneously disposed on the first side of the transparent substrate 11, the light emitting diode 12 can emit a detection light for detecting a liquid to be detected, the photodiode 13 is configured to receive the detection light reflected by the second side surface of the transparent substrate 11, and the photodiode 13 determines whether the second side surface of the transparent substrate 11 is in contact with an air environment or a liquid environment to be detected according to a change of a photocurrent generated by the photodiode 13. It should be noted that, since the second side surface of the transparent substrate 11 serves as a reflecting surface or a refracting surface of the detection light, in order to avoid the influence of the substrate on the transmission of the detection light, the substrate must be the transparent substrate 11, and preferably, the transparency thereof is high, and the optical path loss of the detection light during the transmission process is hardly caused. Optionally, in this embodiment, the material of the transparent substrate 11 may be at least one of sapphire, silicon carbide, and silicon. The sapphire (alumina) substrate is the preferred substrate for manufacturing the light-emitting diode chip, and the sapphire substrate has the advantages of mature production technology, good quality, good stability, high mechanical strength and easiness in cleaning. The silicon carbide substrate has good heat-conducting property, and the heat dissipation of components is effectively enhanced. The silicon substrate also has good heat-conducting property, and the service life of components is effectively prolonged.
As shown in fig. 2, fig. 2 is a schematic diagram of a total reflection phenomenon provided in an embodiment of the present invention, where a critical angle refers to an angle at which a light ray just can be totally reflected when entering an optically thinner medium from the optically denser medium on an interface between the optically denser medium and the optically thinner medium, and when an incident angle θ 1 of the light ray is greater than the critical angle, the light ray is totally reflected and cannot enter the optically thinner medium. Fig. 3 is a schematic structural diagram of the liquid level detecting apparatus in an air environment according to the embodiment of the present invention, in this embodiment, a first interface S1 is formed between the second side surface of the transparent substrate 11 and the space, the transparent substrate 11 is an optically dense medium, the air is an optically sparse medium, the first interface S1 has a first critical angle α 1, and when the incident angle of the detection light L1 is greater than the first critical angle α 1, the detection light L1 is subjected to a total reflection phenomenon. Then, by setting the distance d1 between the light emitting diode 12 and the photodiode 13, the detection light L1 emitted from the light emitting diode 12 is totally reflected on the second side surface of the transparent substrate 11 and then enters the photodiode 13, that is, the incident angle of the detection light L1 on the second side surface of the transparent substrate 11 is larger than the first critical angle α 1, and the totally reflected detection light L1 enters the photodiode 13, so that the photodiode 13 generates a first current value with a larger value.
Fig. 4 is a schematic structural diagram of the liquid level detection apparatus located in the liquid environment to be detected according to the embodiment of the invention, and when the liquid level detection apparatus is placed in the liquid environment to be detected, for example, the second side surface of the transparent substrate 11 contacts or is immersed in the liquid to be detected, a second interface S2 is formed between the transparent substrate 11 and the liquid to be detected, and optionally, the refractive index of the transparent substrate 11 may be larger than the refractive index of the liquid to be detected, the transparent substrate 11 is an optically dense medium, and the liquid to be detected is an optically sparse medium, the second critical angle of the second interface S2 is different from the first critical angle α 1, and the detection light incident to the photodiode 13 also changes, exemplarily, as shown in fig. 4, when the incident angle of the detection light L1 is α 1, total reflection does not occur at the second interface S2, and there may be a portion of the detection light refracted into the liquid to be detected, and the detection light received by the photodiode 13 is less detection light, the photodiode 13 generates a current value with a small value, the current generated by the photodiode 13 is monitored in real time in the embodiment, and if the photodiode 13 detects a sudden change of the current or a large change of the current, it indicates that the liquid level to be detected reaches the position of the liquid level detection device.
Optionally, the thickness of the transparent substrate 11 may be in a range of 100 μm to 200 μm, so that the detection light enters the photodiode 13 after being totally reflected on the second side surface of the transparent substrate 11, and a certain space is provided for a total reflection light path of the detection light, so that the thickness of the transparent substrate 11 is greater than or equal to 100 μm, and in addition, in order to achieve miniaturization of the whole liquid level detection apparatus, the thickness of the transparent substrate 11 is not too thick, and may be less than or equal to 200 μm. Alternatively, the thickness of the transparent substrate 11 may be selected to be 150 μm.
In the embodiment, the transparent substrate is used as the emitting interface of the light emitting diode, a reflecting prism is not required to be additionally arranged, the volume of the liquid level detection device is reduced, and the light emitting diode and the photodiode are arranged on the same substrate at a certain interval, so that the miniaturization of the liquid level detection device is further realized. The liquid level detection device in the embodiment can be suitable for smaller liquid containers to be detected, and can be applied to small equipment such as water dispensers and water purifiers. The liquid level detection device can be arranged on the micro-fluidic pipeline, so that liquid level detection or liquid component analysis and the like can be carried out on liquid to be detected in the micro-fluidic pipeline.
Fig. 5 is a schematic structural diagram of another liquid level detection apparatus provided in the embodiment of the invention, and optionally, the light emitting diode 12 may include a first doped portion 121, a light emitting portion 122 and a second doped portion 123 which are sequentially disposed away from the transparent substrate 11; the photodiode 13 includes a third doped portion 131, a photoelectric conversion portion 132, and a fourth doped portion 133 which are disposed away from the transparent substrate 11 in this order; the first doping part 121 and the third doping part 131 are disposed at the same layer; the light emitting section 122 and the photoelectric conversion section 132 are provided in the same layer; the second doping part 123 and the fourth doping part 133 are disposed at the same layer.
When the light emitting diode 12 and the photodiode 13 are formed, the light emitting diode 12 and the photodiode 13 may be simultaneously fabricated, specifically, the light emitting diode 12 includes a first doped portion 121, a light emitting portion 122, and a second doped portion 123 sequentially formed on the transparent substrate 11, and the photodiode 13 includes a third doped portion 131, a photoelectric conversion portion 132, and a fourth doped portion 133 sequentially formed on the transparent substrate 11. The first doping part 121 and the third doping part 131 may be disposed in the same layer using the same process, the light emitting part 122 and the photoelectric conversion part 132 may be disposed in the same layer using the same process, and the second doping part 123 and the fourth doping part 133 may be disposed in the same layer using the same process, thereby achieving integration of the light emitting diode 12 and the photodiode 13 on the same substrate. The light emitting diode 12 and the photodiode 13 do not need to be arranged on two different chips respectively, and the manufacturing cost of the chips is effectively saved. Here, the light emitting part 122 of the light emitting diode 12 may include a plurality of quantum wells, such that electrons and holes input by the first and second doping parts 121 and 123 of the light emitting diode 12 recombine at the light emitting part 122 to emit photons. The photoelectric conversion portion 132 of the photodiode 13 may include a plurality of quantum wells, and may be capable of receiving light radiation from the outside and generating an induced current, and output to an external circuit by the third and fourth doping portions 131 and 133 of the photodiode 13.
Optionally, the first doping part 121 may be an N-type doping layer, and the second doping part 123 may be a P-type doping layer; the third doping part 131 may be an N-type doping layer, and the fourth doping part 133 may be a P-type doping layer. Alternatively, the first doping part 121 may be a P-type doping layer, and the second doping part 123 may be an N-type doping layer; the third doping part 131 may be a P-type doping layer, and the fourth doping part 133 may be an N-type doping layer. Optionally, the N-type doped layer may be N-type doped gallium nitride, and the P-type doped layer may be P-type doped gallium nitride.
With continued reference to fig. 5, optionally, an insulating layer 14 may be disposed between the light emitting diode 12 and the photodiode 13; the insulating layer 14 is a non-light-transmitting material. In this embodiment, a non-transparent insulating layer 14 is formed between the light emitting diode 12 and the photodiode 13, so that the detection light emitted by the light emitting diode 12 can be prevented from directly irradiating the photodiode 13, the photocurrent detection accuracy of the photodiode 13 is improved, the light sensitivity of the whole liquid level detection device is improved, and the liquid level measurement precision is improved.
Optionally, the monolithic substrate integrates the light emitting diode and the photodiode in a flexible packaging manner, and the embodiment may use a conventional bonding manner of a front-mounted substrate, a lead frame manner, a flip-chip manner, and the like for packaging, and is not limited to a single packaging form.
Based on the same conception, the embodiment of the invention also provides a liquid level detection method. Fig. 6 is a schematic flow chart of a liquid level detection method according to an embodiment of the present invention, and as shown in fig. 6, the method according to the embodiment includes the following steps:
step S110, placing the liquid level detection device in an air environment, controlling the light emitting diode to emit detection light, so that the photodiode receives the detection light totally reflected by the first interface between the second side surface of the transparent substrate and the air, and recording a first current value formed by the photodiode.
Step S120, placing the transparent substrate of the liquid level detection device in a liquid measurement environment to be measured, controlling the light emitting diode to emit detection light, enabling the photodiode to receive the detection light reflected by the second side surface of the transparent substrate, and recording a second current value formed by the photodiode.
Step S130, if the difference value between the first current value and the second current value is larger than a first set threshold value, judging that the liquid level of the liquid to be detected reaches the position of the liquid level detection device.
When the liquid level detection device does not detect the liquid level to be detected, the light emitting diode is turned on to make the detection light generate total reflection, the photodiode forms a first current value, when the liquid level detection device is placed in a liquid measurement environment to be detected, the photodiode forms a second current value, the difference value between the first current value and the second current value is detected, if the difference value is almost zero, the second side surface of the transparent substrate and air form a first interface, if the difference value is greater than the first set threshold value, it indicates that the second current value has a sudden change, that is, the medium contacted with the second side surface of the transparent substrate has changed, the second side surface of the transparent substrate is contacted with the liquid to be detected to form a second interface, and the liquid level of the liquid to be detected is equal to or higher than the current height of the liquid level detection device. In this embodiment, when carrying out level measurement to the liquid that awaits measuring, can follow evenly to set up a plurality of liquid level detection device in the vertical direction of height, the liquid level height of the liquid that awaits measuring is finally judged to the size of the second current value through each liquid level detection device output.
In the embodiment of the invention, the liquid level detection device comprises a light emitting diode and a photodiode which are formed on the first side of the same transparent substrate, a first interface is formed between the second side surface of the transparent substrate and air, the first interface has a first critical angle, the embodiment controls the arrangement distance between the light emitting diode and the photodiode, so that the incident angle of detection light on the second side surface of the transparent substrate is larger than the first critical angle, the detection light is incident into the photodiode through total reflection in an air environment, the first current value generated by the photodiode is larger, when the second side surface of the transparent substrate is a liquid measuring environment to be measured, the photodiode generates a second current value, when the second side surface of the transparent substrate is in contact with the liquid to be measured to form a second interface, the light path of the detection light is influenced not to be in a total reflection state, the second current value that then photodiode produced is less, judge the liquid level of the liquid that awaits measuring and reach or exceed this liquid level detection device height of locating from this, in this embodiment, emitting diode and photodiode have been integrated simultaneously on liquid level detection device's the same substrate, the integration level is higher, for the scheme of integrated independent emitting diode component and photodiode in the same device, effectively reduce liquid level detection device's overall size, save the cost of manufacture, can be applicable to large-scale equipment and small-size equipment simultaneously, improve liquid level detection device's suitability, in addition, the substrate is transparent substrate, can regard as the reflection boundary of detection light, need install the prism in addition, further reduced liquid level detection device's volume, improve the integration level.
Fig. 7 is a schematic structural diagram of a liquid level detection device in a liquid measurement environment to be measured according to an embodiment of the present invention, fig. 8 is a schematic structural diagram of another liquid level detection device in a liquid measurement environment to be measured according to an embodiment of the present invention, and alternatively, as shown in fig. 7, the liquid measurement environment to be measured may be an inner side of a side wall of a container in which a liquid 3 to be measured is placed; the transparent substrate 11 is used for contacting with the liquid 3 to be measured; alternatively, as shown in fig. 8, the liquid measurement environment to be measured may be the outside of the transparent sidewall of the container in which the liquid 3 to be measured is placed; the transparent substrate 11 is attached to the outside of the transparent sidewall 2.
The environment for measuring the liquid to be measured in this embodiment may be an environment that can be in direct contact with the liquid to be measured, as shown in fig. 7, a transparent substrate 11 of the liquid level detection device may be disposed inside a sidewall 2 of a container of the liquid to be measured 3, so that a second side surface of the transparent substrate 11 can be in direct contact with the liquid to be measured, thereby measuring the liquid level of the liquid to be measured, fig. 7 shows a structure in which the liquid level detection device passes through the sidewall 2, in this embodiment, the entire liquid level detection device may also be hermetically encapsulated and then placed in the liquid to be measured, as shown in fig. 9, fig. 9 is a schematic structural diagram of another liquid level detection device provided in the embodiment of the present invention in the environment for measuring the liquid to be measured, the liquid level detection device 1 is directly immersed in the liquid to be. In this embodiment, the liquid to be measured may be water, oil, a chemical reagent, and the like, which is not limited in this embodiment.
Except that the scheme that the second side surface of transparent substrate 11 directly contacts with the liquid 3 that awaits measuring, transparent substrate 11 can not contact with the liquid 3 that awaits measuring in this embodiment, as shown in fig. 8, if the lateral wall 2 of the container that holds the liquid 3 that awaits measuring is transparent material, then can set up the attached lateral wall 2 of the second side surface of transparent substrate 11 of liquid level detection device, the liquid 3 that awaits measuring sees through transparent lateral wall 2 and can influence the reflection of detection light at the second side surface of transparent substrate 11 equally to detect the liquid level of the liquid that awaits measuring. This embodiment scheme is when carrying out liquid level detection to the liquid 3 that awaits measuring, and direct contact liquid 3 that awaits measuring to can not pollute the liquid 3 that awaits measuring, for example, if the liquid 3 that awaits measuring is the pure water in the drinking machine, can obey the outside of transparent cask with the second side surface subsides of transparent substrate 11 of liquid level detection device, thereby detect the liquid level of pure water.
Alternatively, the liquid to be measured may be a liquid in a microfluidic channel. In this embodiment, the liquid level detection device can be miniaturized, and the miniaturized liquid level detection device can be applied to miniaturized equipment, for example, the liquid level detection device can be arranged on a microfluidic pipeline, so that liquid level detection or liquid component analysis and the like can be performed on liquid to be detected in the microfluidic pipeline. Specifically, as shown in fig. 10, fig. 10 is a schematic structural diagram of a liquid level detection apparatus in a microfluidic measurement environment according to an embodiment of the present invention, and it can be seen that the size of the microfluidic channel 4 is extremely small, even smaller than the chip size of the liquid level detection apparatus 1, and exemplarily, the diameter of the microfluidic channel 4 is different from 100 μm to 800 μm, for example, the diameter of the microfluidic channel 4 is generally 400 μm. The miniaturized liquid level detection device 1 can be attached to the outer side wall of the microfluidic pipeline 4, and the liquid level detection device 1 can measure whether the liquid to be detected flows through the microfluidic pipeline 4 or not, and can even further distinguish several different refractive index typical values of detection light, so that the liquid component of the liquid to be detected is analyzed.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (10)
1. A liquid level detection device, comprising: a transparent substrate;
the light emitting diode is arranged on the first side of the transparent substrate and used for emitting detection light;
the photodiode is arranged on the first side of the transparent substrate and used for receiving the detection light reflected by the surface of the second side of the transparent substrate;
wherein a first interface is formed between the second side surface of the transparent substrate and air; the first interface presents a first critical angle; the incident angle of the detection light ray on the second side surface of the transparent substrate is larger than the first critical angle.
2. The liquid level detection apparatus according to claim 1, wherein the light emitting diode includes a first doped portion, a light emitting portion, and a second doped portion disposed away from the transparent substrate in this order; the photodiode comprises a third doping part, a photoelectric conversion part and a fourth doping part which are sequentially far away from the transparent substrate;
the first doping part and the third doping part are arranged on the same layer; the light emitting section and the photoelectric conversion section are provided in the same layer; the second doping portion and the fourth doping portion are arranged on the same layer.
3. The liquid level detection device of claim 2, wherein the first doped portion is an N-type doped layer and the second doped portion is a P-type doped layer; the third doping part is an N-type doping layer, and the fourth doping part is a P-type doping layer.
4. The liquid level detection device of claim 2, wherein an insulating layer is disposed between the light emitting diode and the photodiode; the insulating layer is made of non-light-transmitting materials.
5. The liquid level detection apparatus of claim 2, wherein the material of the transparent substrate is at least one of sapphire, silicon carbide, and silicon.
6. The liquid level detection apparatus of claim 2, wherein the transparent substrate has a refractive index greater than a refractive index of the liquid to be measured.
7. The liquid level detection apparatus of claim 2, wherein the transparent substrate has a thickness in a range of 100 μm to 200 μm.
8. A liquid level detection method applied to the liquid level detection apparatus according to any one of claims 1 to 7, comprising:
placing the liquid level detection device in an air environment, controlling the light emitting diode to emit detection light, enabling the photodiode to receive the detection light totally reflected by a first interface between the second side surface of the transparent substrate and the air, and recording a first current value formed by the photodiode;
placing the transparent substrate of the liquid level detection device in a liquid measurement environment to be measured, controlling the light emitting diode to emit detection light, enabling the photodiode to receive the detection light reflected by the second side surface of the transparent substrate, and recording a second current value formed by the photodiode;
and if the difference value between the first current value and the second current value is greater than a first set threshold value, judging that the liquid level of the liquid to be detected reaches the position of the liquid level detection device.
9. The liquid level detection method according to claim 8, wherein the liquid measurement environment to be measured is outside a transparent sidewall of a container in which the liquid to be measured is placed; the transparent substrate is attached to the outer side of the transparent side wall; or,
the liquid to be measured is measured in the measuring environment, namely the inner side of the side wall of the container for placing the liquid to be measured; the transparent substrate is used for contacting with the liquid to be measured.
10. The liquid level detection method of claim 8, wherein the liquid to be detected is a liquid in a microfluidic pipeline.
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