CN110646059A - Liquid level detection method and device - Google Patents

Liquid level detection method and device Download PDF

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Publication number
CN110646059A
CN110646059A CN201910942416.8A CN201910942416A CN110646059A CN 110646059 A CN110646059 A CN 110646059A CN 201910942416 A CN201910942416 A CN 201910942416A CN 110646059 A CN110646059 A CN 110646059A
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infrared
level
receiving head
value
liquid
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CN110646059B (en
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赵东
赵自荐
刁大志
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Shenzhen Heertai Intelligent Technology Co Ltd Small Appliances
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Shenzhen Heertai Intelligent Technology Co Ltd Small Appliances
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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
    • 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

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  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Fluid Mechanics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Thermal Sciences (AREA)
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  • General Health & Medical Sciences (AREA)
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  • Pathology (AREA)
  • Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)

Abstract

The embodiment of the invention provides a liquid level detection method and a liquid level detection device, wherein the method comprises the following steps: turning on an infrared photoelectric sensor; adjusting the working state value of an infrared emission tube to adjust the intensity of infrared light emitted by the infrared emission tube; recording the working state value of the infrared transmitting tube as the conduction value of the infrared photoelectric sensor when the infrared light intensity is within the preset luminous intensity range; and judging the liquid level detection result at the first height of the liquid container wall according to the conduction value. By adopting the method and the device, the interference existing in the conventional level detection mode can be effectively avoided, and the reliability of the liquid level detection result is improved.

Description

Liquid level detection method and device
Technical Field
The invention relates to the technical field of liquid level sensing, in particular to a liquid level detection method and a liquid level detection device.
Background
In the washing machine with the automatic detergent feeding function in the market, the detergent storage box is arranged in the washing machine, so that a user cannot directly see the consumption condition of the detergent. When the amount of the detergent is insufficient, a user needs to be reminded of adding the detergent in time, so that the liquid level of the detergent needs to be detected.
At present, the most common detergent liquid level detection method is to arrange a probe, specifically to arrange a metal electrode at a certain position of a detergent storage box, and to judge the liquid level of the detergent through the conductive property of the detergent. However, when the electrode of the probe applies a dc voltage to the detergent, the electrode is in a plating state, and a protective film is formed on the surface of the electrode, so that the whole detection circuit cannot work normally due to the non-conductivity of the oxide film, and the washing machine cannot correctly determine the level of the detergent.
Disclosure of Invention
The embodiment of the invention provides a liquid level detection method and a liquid level detection device, aiming at avoiding external interference and improving the reliability of a liquid level detection result.
In a first aspect, the embodiment of the present invention provides a liquid level detection method, which is applied to a liquid level detection device, where the liquid level detection device includes an infrared photoelectric sensor, the infrared photoelectric sensor includes an infrared transmitting tube and an infrared receiving head, the infrared transmitting tube and the infrared receiving head are respectively located at different positions of a first height of a liquid container wall, the infrared transmitting tube is used to emit infrared light to the infrared receiving head, and the infrared receiving head is used to adjust a conduction state of the infrared photoelectric sensor according to the infrared light;
the method comprises the following steps:
turning on an infrared photoelectric sensor;
adjusting the working state value of the infrared emission tube to adjust the intensity of infrared light emitted by the infrared emission tube;
recording the working state value of the infrared transmitting tube as the conduction value of the infrared photoelectric sensor when the infrared light intensity is within a preset light-emitting intensity range;
and judging the liquid level detection result at the first height of the liquid container wall according to the conduction value.
The infrared receiving head is used for outputting a first level or a second level according to the received infrared light intensity so as to adjust the conduction state of the infrared photoelectric sensor;
the adjusting of the working state value of the infrared emission tube comprises:
adjusting the working state value of the infrared transmitting tube according to the first level output by the infrared receiving head;
when the output level of the infrared receiving head is changed from the first level to the second level, the infrared light intensity is determined to be within the preset luminous intensity range.
The determining that the infrared light intensity is within the preset light-emitting intensity range when the output level of the infrared receiving head changes from the first level to the second level further comprises:
adjusting the working state value of the infrared transmitting tube according to the second level output by the infrared receiving head until the output level of the infrared receiving head is changed from the second level to the first level;
the recording of the working state value of the infrared emission tube as a conduction value when the infrared light intensity is within a preset light intensity range comprises:
and recording the average value of a plurality of working state values of the infrared transmitting tube between a first moment and a second moment as the conduction value, wherein the first moment is the moment when the output level of the infrared receiving head is changed from the first level to the second level, and the second moment is the moment when the output level of the infrared receiving head is changed from the second level to the first level.
The infrared receiving head comprises a photosensitive diode, a signal amplifier and a triode, wherein:
the photodiode converts the received infrared light into an electric signal, the electric signal is amplified by the signal amplifier and then output to a base electrode of the triode, and the triode outputs the first level or the second level according to the electric signal received by the base electrode.
Wherein the determining a liquid level detection result at the first height of the liquid container wall according to the conduction value comprises:
if the conduction value is not within the preset working state range, determining that liquid exists at the first height, and adjusting the working current of the infrared emission tube to enable the infrared photoelectric sensor to be in a corresponding working state range when the infrared photoelectric sensor is conducted when the preset working state value is that air exists at the first height; and if the conduction value is within the preset working state range, determining that no liquid exists at the first height of the liquid container wall.
Wherein the determining a liquid level detection result at the first height of the liquid container wall according to the conduction value further comprises:
and under the condition that the liquid is determined to exist at the first height of the wall of the liquid container, determining the type of the liquid in the liquid container according to the currently recorded conduction value and the relation between the preset conduction value and the type of the liquid.
In a second aspect, a liquid level detecting device is provided for an embodiment of the present invention, which includes an infrared photoelectric sensor, where the infrared photoelectric sensor includes an infrared transmitting tube and an infrared receiving head, the infrared transmitting tube and the infrared receiving head are respectively located at different positions of a first height of a wall of a liquid container, the infrared transmitting tube is used for emitting infrared light to the infrared receiving head, and the infrared receiving head is used for adjusting a conducting state of the infrared photoelectric sensor according to the infrared light;
the device further comprises: the starting unit is used for starting the infrared photoelectric sensor;
the adjusting unit is used for adjusting the working state value of the infrared transmitting tube so as to adjust the intensity of the infrared light emitted by the infrared transmitting tube;
the recording unit is used for recording the working state value of the infrared emission tube as a conduction value when the infrared light intensity is within a preset light intensity range;
and the judging unit is used for judging the liquid level detection result at the first height of the liquid container wall according to the conduction value.
Optionally, the working state value adjusting subunit is configured to adjust the working state value of the infrared transmitting tube according to the first level output by the infrared receiving head. The infrared receiving head is used for outputting a first level or a second level according to the infrared light intensity so as to adjust the conduction state of the infrared photoelectric sensor. The infrared receiving head comprises a photosensitive diode, a signal amplifier and a triode, wherein the photosensitive diode converts received infrared light into an electric signal, the electric signal is amplified by the signal amplifier and then output to a base of the triode, and the triode outputs the first level or the second level according to the electric signal received by the base.
Optionally, the determining subunit is configured to determine that the infrared light intensity is within the preset light-emitting intensity range when the output level of the infrared receiving head changes from the first level to the second level.
Optionally, the apparatus further comprises:
the working state value adjusting unit is used for adjusting the working state value of the infrared transmitting tube according to the second level output by the infrared receiving head until the output level of the infrared receiving head is changed from the second level to the first level;
optionally, the recording unit is configured to record an average value of a plurality of operating state values of the infrared transmitting tube between a first time and a second time as the conduction value, where the first time is a time when the output level of the infrared receiving head changes from the first level to the second level, and the second time is a time when the output level of the infrared receiving head changes from the second level to the first level.
Optionally, the determining unit is configured to determine that liquid exists at the first height of the liquid container wall if the conduction value is not within the preset working state range, where the preset working state range is a corresponding working state range when air exists at the first height and the infrared photoelectric sensor is turned on by adjusting the working state value of the infrared transmitting tube; and if the conduction value is within the preset working state range, determining that no liquid exists at the first height of the liquid container wall.
Optionally, the determining unit is further configured to determine, when it is determined that liquid exists at the first height of the liquid container wall, a liquid type in the liquid container according to the currently recorded conduction value and a relationship between a preset conduction value and the liquid type.
In a third aspect, a liquid level detection device is provided for an embodiment of the present invention, which includes a processor and an infrared photoelectric sensor, where the photoelectric sensor includes an infrared emission tube and an infrared receiving head, and the infrared emission tube and the infrared receiving head are respectively located at different positions of a first height of a wall of a liquid container;
the infrared transmitting tube is connected with the processor and is used for emitting infrared light to the infrared receiving hair;
the infrared receiving head is connected with the processor and used for receiving infrared light emitted by the infrared emitting tube;
the processor is used for adjusting the working state value of the infrared emission tube so as to adjust the intensity of infrared light emitted by the infrared emission tube, recording the working state value of the infrared emission tube as the conduction value of the infrared photoelectric sensor when the intensity of the infrared light is within a preset luminous intensity range, and judging the liquid level detection result of the first height of the wall of the liquid container according to the conduction value.
In the embodiment of the invention, the processor turns on the infrared photoelectric sensor; adjusting the working state value of an infrared emission tube to adjust the intensity of infrared light emitted by the infrared emission tube; recording the working state value of the infrared transmitting tube as the conduction value of the infrared photoelectric sensor when the infrared light intensity is within the preset luminous intensity range; and judging the liquid level detection result at the first height of the liquid container wall according to the conduction value. Because the liquid level detection result is determined by the conduction value of the infrared photoelectric sensor, rather than directly probing the electrode into the liquid, the influence of an oxide film on a detection circuit is avoided, and the liquid level can be accurately detected, so that the reliability of the liquid level detection result is improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic view of a scene of a liquid level detection method according to an embodiment of the present invention;
FIG. 2 is a schematic flow chart of a liquid level detection method according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a liquid level detecting device according to an embodiment of the present invention;
FIG. 4 is a schematic flow chart of another method for detecting liquid level according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of another fluid level sensing device provided by an embodiment of the present invention;
FIG. 6 is a schematic flow chart of another method for detecting fluid level according to an embodiment of the present invention;
FIG. 7 is a schematic flow chart of another method for detecting fluid level according to an embodiment of the present invention;
fig. 8 is a schematic structural diagram of a liquid level detection apparatus according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Fig. 1 is a schematic view of a scene of a liquid level detection method according to an embodiment of the present invention. As shown in FIG. 1, the infrared photoelectric sensor comprises an infrared transmitting tube 101 and an infrared receiving head 102, wherein the infrared transmitting tube 101 is used for emitting infrared light to the infrared receiving head 102, and the infrared transmitting tube 101 and the infrared receiving head 102 are respectively positioned at different positions of a first height of a liquid container wall 103. Wherein the infrared transmitting tube 101 and the infrared receiving head 102 can be located at different positions of the same height of the liquid container wall 103, the infrared photoelectric sensor can be isolated from the liquid in the container by a transparent anti-corrosion material and located at the inner side of the liquid container wall 103, and when the liquid container is a transparent container, the infrared photoelectric sensor can also be located at the outer side of the liquid container wall 103. And the processor judges the liquid level detection result of the position of the infrared photoelectric sensor according to the conduction value of the infrared photoelectric sensor.
The method embodiments in the present application are described with reference to a liquid level detection device as an implementation subject, wherein the liquid level detection device may include the infrared photoelectric sensor and the processor.
Fig. 2 is a schematic flow chart of a liquid level detection method according to an embodiment of the present invention. As shown in fig. 2, the method embodiment comprises the following steps:
s101, turning on an infrared photoelectric sensor.
In some possible implementations, the liquid level detection device may include a digital-to-analog converter and a voltage-to-current converter, wherein an output of the digital-to-analog converter is connected to an input of the voltage-to-current converter. Specifically, the liquid level detection device can output voltage to the voltage-current converter through the digital-analog converter, the voltage-current converter outputs current to the infrared transmitting tube according to the voltage acquired by the input end, the current is used for driving the infrared transmitting tube to emit infrared light, and the infrared receiving head receives the infrared light emitted by the infrared transmitting tube, so that the infrared photoelectric sensor is started.
In other possible implementation manners, the liquid level detection device may change a duty ratio of a Pulse Width Modulation (PWM) wave output from an IO port of a processor (e.g., a single chip microcomputer) (a ratio of time for maintaining a high level in a PWM rectangular wave to a period of the PWM wave), so that the processor (e.g., the single chip microcomputer) outputs a voltage with an adjustable voltage value, the voltage is used to drive an infrared transmitting tube to emit infrared light, and an infrared receiving head receives the infrared light emitted by the infrared transmitting tube, thereby turning on the infrared photoelectric sensor.
And S102, adjusting the working state value of the infrared transmitting tube.
Specifically, a processor (such as a single chip microcomputer) in the liquid level detection device adjusts the working state value of the infrared transmitting tube according to the intensity of the infrared light received by the infrared receiving head, so that the intensity of the infrared light emitted by the infrared transmitting tube is changed. The liquid level detection device can change the output current value of the photosensitive diode in the infrared receiving head according to the intensity of infrared light received by the infrared receiving head so as to adjust the working state value of the infrared transmitting tube. If the intensity of the infrared light received by the infrared receiving head is smaller than the minimum luminous intensity in the preset luminous intensity range, a processor (such as a singlechip) in the liquid level detection device increases the working state value of the infrared transmitting tube; if the infrared light intensity received by the infrared receiving head is greater than the maximum luminous intensity in the preset luminous intensity range, a processor (such as a singlechip) in the liquid level detection device reduces the working state value of the infrared transmitting tube. The preset light-emitting intensity range is the range of the intensity of infrared light emitted by the infrared emission tube when the infrared photoelectric sensor is in a conducting state.
The working state value of the infrared emission tube can be any one of the working current of the infrared emission tube, the working voltage of the infrared emission tube or the input quantity control value of a digital-to-analog converter in a processor (such as a singlechip) in the liquid level detection device. Please refer to the description of the following embodiments for a specific implementation manner of adjusting the operating state value of the infrared transmitting tube.
S103, judging whether the intensity of the infrared light received by the infrared receiving head is within a preset light-emitting intensity range.
Specifically, if the processor (e.g., a single chip microcomputer) in the liquid level detection device receives that the infrared light intensity received by the infrared receiving head is not within the preset light-emitting intensity range, the step S102 is executed again; if the intensity of the infrared light received by the infrared receiving head is within the preset light intensity range, which is received by a processor (such as a single chip microcomputer) in the liquid level detection device, the step S104 is executed.
And S104, recording the working state value of the infrared transmitting tube as a conduction value when the intensity of the infrared light received by the infrared receiving head is within a preset luminous intensity range.
Specifically, when the intensity of the infrared light received by the infrared receiving head is within a preset luminous intensity range, the liquid level detection device determines that the infrared photoelectric sensor is in a conducting state, and then the working state value of the infrared transmitting tube corresponding to the conducting state is recorded as a conducting value.
S105, judging the liquid level detection result at the first height of the liquid container wall according to the conduction value.
Specifically, the liquid level detection device compares the conduction value with a preset working state range, if the conduction value is not in the preset working state range, it is determined that liquid exists at the first height, if the conduction value is in the preset working state range, it is determined that no liquid exists at the first height, and the preset working state range is a corresponding working state range when air exists at the first height and the infrared transmitting tube is switched on by adjusting the working state value of the infrared transmitting tube. Please refer to the following description for the manner of determining whether the conduction value is within the preset operating state range and adjusting the operating state value of the infrared transmitting tube to turn on the infrared photoelectric sensor when air exists at the first height.
According to the technical scheme, the liquid level detection result is determined by the conduction value of the infrared photoelectric sensor instead of directly probing the electrode into the liquid, so that the influence of an oxide film on a detection circuit is avoided, the liquid level can be accurately detected, and the reliability of the liquid level detection result is improved. In addition, if the liquid is required to be detected at a plurality of positions, only the infrared photoelectric sensors are required to be arranged at the corresponding heights of the positions, and the operation is simple.
The technical solution according to the embodiment of the present invention will be described in detail below with respect to the three different operating state values of the infrared emission tube.
For ease of understanding, the operation of a liquid level detection apparatus used in the embodiments of the present invention will be described first. Fig. 3 is a schematic diagram of a liquid level detecting device according to an embodiment of the present invention.
The working principle shown in fig. 3 is as follows: the processor U1 outputs a voltage value through the input digital quantity of the analog-digital converter and outputs the output voltage value to the base of the output power tube, the base of the output power tube outputs current to the infrared emission tube D2 according to the output voltage value, the infrared emission tube D2 can emit infrared light to the infrared receiving head according to the current value provided by the processor U1, the photodiode D1 in the infrared receiving head can convert the received infrared light into an electric signal (current value or voltage value) and provide the electric signal to the comparator COMP1, the comparator COMP1 obtains the result whether the electric signal output by the D1 is in the electric signal range output by the D1 under the preset luminous intensity range by outputting high and low levels, if the processor U1 receives the low level output by the infrared receiving head, the infrared light intensity received by the infrared receiving head is not in the preset luminous intensity range, namely, the infrared photoelectric sensor (normally low) is in a cut-off state, the processor U1 adjusts the working current of the infrared transmitting tube D2 according to the illumination intensity of the infrared light emitted by the infrared transmitting tube D2; if the processor U1 receives the high level output by the infrared receiving head, it indicates that the intensity of the infrared light received by the infrared receiving head is within the preset light intensity range, that is, the infrared photoelectric sensor (normally low) is in a conducting state, records the working state value of the infrared transmitting tube D2 at this time, where the working state value may be a working voltage value or an input quantity control value or a working current value of the infrared transmitting tube, and determines the working state value of the infrared transmitting tube as a conducting value when the infrared photoelectric sensor (normally low) is in a conducting state, and determines the liquid level detection result of the height where the infrared photoelectric sensor is located according to the conducting value.
Referring to fig. 4, a schematic flow chart of another liquid level detection method according to an embodiment of the invention is provided. As shown in fig. 4, this method embodiment includes the steps of:
s201, turning on an infrared photoelectric sensor.
Here, the liquid level detection device may include a single chip microcomputer with an operating voltage of 3.3V and a built-in digital-to-analog converter word length of 10 bits, and the data expression range of the device is 0 to 1024. The liquid level detection device can output a corresponding voltage value (ranging from 0 to 3.3V) by changing the value (ranging from 0 to 1024) of the input data quantity of the digital-to-analog converter, then convert the output voltage value (ranging from 0 to 3.3V) of the analog-to-digital converter into a corresponding current value (ranging from 0 to 20mA) through the voltage-current converter, and output the current value to the infrared emission tube for starting the infrared photoelectric sensor.
S202, adjusting the working current value of the infrared emission tube.
Specifically, a processor (such as a single chip microcomputer) in the liquid level detection device adjusts the working current value of the infrared transmitting tube according to the intensity of the infrared light received by the infrared receiving head, so that the intensity of the infrared light emitted by the infrared transmitting tube is changed, and the output current value of a photodiode in the infrared receiving head is further changed. If the intensity of the infrared light received by the infrared receiving head is smaller than the minimum luminous intensity in the preset luminous intensity range, a processor (such as a singlechip) in the liquid level detection device increases the working current value of the infrared transmitting tube; if the intensity of the infrared light received by the infrared receiving head is greater than the maximum luminous intensity in the preset luminous intensity range, a processor (such as a singlechip) in the liquid level detection device reduces the working current value of the infrared transmitting tube. The preset light-emitting intensity range is the range of the intensity of infrared light emitted by the infrared emission tube when the infrared photoelectric sensor is in a conducting state.
S203, judging whether the intensity of the infrared light received by the infrared receiving head is within a preset light-emitting intensity range.
In a possible implementation scheme, a photodiode in the infrared receiving head converts the light intensity of an infrared transmitting tube corresponding to the conduction state of the infrared photoelectric sensor into an output current value of 10uA to 12uA, and a processor (such as a single chip microcomputer) in the liquid level detection device determines that the output current value of the photodiode in the infrared receiving head is within the range of 10uA to 12uA, and the intensity of the infrared light received by the infrared receiving head is within a preset light intensity range.
For example, the photodiode converts the received infrared light intensity of the infrared emission tube at the working current of 8mA adjusted in step S202 into a 9uA current value, the infrared receiving head compares the output current value 9uA of the photodiode with the output current value 10uA-12uA of the photodiode within the preset light-emitting intensity range to obtain a judgment result that the infrared light intensity received by the infrared receiving head is not within the preset light-emitting intensity range, and sends the judgment result to a processor (such as a single chip microcomputer) in the liquid level detection device. The processor (e.g., a single chip) in the liquid level detection device executes step S202 after receiving the determination result that the infrared light intensity received by the infrared receiving head is not within the preset light-emitting intensity range.
For another example, the photodiode converts the received infrared light intensity of the infrared emission tube at the working current of 9mA adjusted in step S202 into a 10uA current value, the infrared receiving head compares the output current value 10uA of the photodiode with the output current value 10uA-12uA of the photodiode within the preset light-emitting intensity range to obtain a judgment result that the infrared light intensity received by the infrared receiving head is within the preset light-emitting intensity range, and sends the judgment result to a processor (such as a single chip microcomputer) in the liquid level detection device. The processor (e.g., a single chip microcomputer) in the liquid level detection device executes step S204 after receiving the judgment result that the intensity of the infrared light received by the infrared receiving head is within the preset light intensity range.
It can be understood that, in a possible implementation manner, step S202 is executed if a processor (e.g., a single chip microcomputer) in the liquid level detection device receives a determination result that the infrared light intensity received by the infrared receiving head is not within a preset light-emitting intensity range (the output current value of the photodiode in the infrared receiving head is not within a range of 10uA to 12 uA); if the processor (e.g., a single chip) in the liquid level detection device receives the judgment result that the intensity of the infrared light received by the infrared receiving head is within the preset light-emitting intensity range (the output current value of the photodiode in the infrared receiving head is within the range of 10uA-12 uA), the step S204 is executed.
And S204, recording the working current value of the infrared transmitting tube as a conduction value when the intensity of the infrared light received by the infrared receiving head is within a preset luminous intensity range.
In one possible implementation manner, the liquid level detection device determines that the infrared photoelectric sensor is in a conducting state when the intensity of the infrared light received by the infrared receiving head is within a preset light-emitting intensity range, and records a working current value of the infrared transmitting tube corresponding to the conducting state as a conducting value.
For example, in step S203, the photodiode converts the received infrared light intensity of the infrared emission tube at the working current of 9mA into a 10uA current value, the 10uA current value is input into the comparator and compared with the output current value of 10uA-12uA of the photodiode within the preset light emission intensity range, the comparator outputs a high level indicating that the infrared light intensity received by the infrared receiving head is within the preset light emission intensity range, the processor (e.g., a single chip) in the comparator determines that the infrared photoelectric sensor (normally low) is in a conducting state at this time, and records the working current of 9mA of the infrared emission tube corresponding to the conducting state as a conducting value.
S205, judging the liquid level detection result at the first height of the liquid container wall according to the conduction value.
Specifically, the liquid level detection device compares the working current value of the corresponding infrared emission tube when the infrared photoelectric sensor is in the on state with a preset working current range, if the working current value of the corresponding infrared emission tube when the infrared photoelectric sensor is in the on state is not in the preset working current range, it is determined that liquid exists at the first height, and if the working current value of the corresponding infrared emission tube when the infrared photoelectric sensor is in the on state is in the preset working current range, it is determined that no liquid exists at the first height. The preset working current range is the corresponding working current range of the infrared transmitting tube when the infrared photoelectric sensor is in a conducting state (the intensity of the infrared light received by the infrared receiving head is within the preset luminous intensity range) when air exists between the infrared transmitting tube and the infrared receiving head.
For example, when the output current value of the photodiode in the infrared receiving head is within the range of 10uA to 12uA, the processor (e.g., a single chip) in the liquid level detection device determines that the intensity of the infrared light received by the infrared receiving head is within the preset light intensity range. When air exists between the infrared transmitting tube and the infrared receiving head, a processor (such as a singlechip) in the liquid level detection device outputs a voltage signal by controlling the input quantity of a digital-to-analog converter, the voltage signal outputs 14mA current to the infrared transmitting tube through the voltage-to-current converter to drive the infrared transmitting tube to work to emit infrared light, a photodiode in the infrared receiving head converts the received infrared light into a 9uA current signal and outputs the converted 9uA current signal to a comparator, obviously, the 9uA is not in the range of 10uA-12uA, the comparator outputs low level, an infrared photoelectric sensor (normally low) is in a cut-off state at the moment, the processor (such as the singlechip) in the liquid level detection device increases the working current of the infrared transmitting tube to 15mA according to the low level output by the infrared receiving head, the photodiode in the infrared receiving head converts the received infrared light into a 10uA current signal, and outputting the converted 10uA current signal to a comparator, wherein the 10uA is obviously within the range of 10uA-12uA, and the comparator outputs high level. At this time, the level output by the infrared receiving head and received by a processor (such as a singlechip) in the liquid level detection device is changed from a low level to a high level, the infrared photoelectric sensor (normally low) is determined to be in a conducting state, and the working current 15mA of the infrared transmitting tube at this time is recorded as a conducting value of the infrared photoelectric sensor when air exists between the infrared transmitting tube and the infrared receiving head. By analogy, when a processor (such as a single chip microcomputer) in the liquid level detection device obtains that air exists between the infrared emission tube and the infrared receiving head, 10 working current values of the infrared emission tube are respectively 15mA, 15.2mA, 16mA, 15.5mA, 15.7mA, 15.1mA, 15.8mA, 15mA, 16mA and 15.3mA when the infrared photoelectric sensor is in a conduction state for 10 times (the intensity of infrared light received by the infrared receiving head is within a preset luminous intensity range), and it is determined that 15mA-16mA is in the preset working current range of the infrared emission tube.
For example, after the processor (e.g., a single chip microcomputer) in the liquid level detection device executes step S204 to obtain the conduction value of 9mA, the conduction value is compared with the preset working current range of 15mA to 16mA of the infrared emission tube, and it is obvious that the conduction value of 9mA is not within the preset working current range of 15mA to 16mA, and it is determined that the liquid exists at the first height.
Optionally, the liquid level detection device may further determine the type of the liquid in the liquid container according to the currently recorded conduction value and a relationship between a preset conduction value and the type of the liquid.
Specifically, a processor (e.g., a single chip) in the liquid level detection device may determine whether liquid exists at the first height according to the currently recorded conduction value and a preset conduction value table (as shown in table 1) of the infrared photoelectric sensor in different liquid types, and if liquid exists at the first height, may also determine the type of liquid in the liquid container.
TABLE 1 conductivity value table for mid-IR photoelectric sensor in different liquid types
Figure BDA0002223276880000081
For example, after the processor (e.g., a single chip) in the liquid level detection device executes step S204 to obtain the conduction value of 9mA, the processor is matched with a preset conduction current value table (shown in table 1) of the infrared photoelectric sensor in different liquid types, and it is determined that liquid exists at the first height and the type of the liquid in the liquid container is C.
Because the liquid level detection result is determined by the working current value of the infrared transmitting tube when the infrared photoelectric sensor is in a conducting state, rather than directly probing the electrode into liquid, the influence of an oxide film on a detection circuit is avoided, and the liquid level can be accurately detected so as to improve the reliability of the liquid level detection result.
For ease of understanding, the operation of another liquid level detection device used in the embodiment of the present invention will be described. Fig. 5 is a schematic diagram of another liquid level detecting device according to an embodiment of the present invention.
The working principle shown in fig. 5 is as follows: the processor U1 can output voltage value by digital quantity input by digital-to-analog converter and output the output voltage value to the input end of the voltage-to-current converter, the voltage-to-current converter outputs current to the infrared emission tube D2 according to the output voltage value of the digital-to-analog converter, the infrared emission tube D2 can emit infrared light to the infrared receiving head according to the current value provided by the processor, the photodiode D1 in the infrared receiving head can convert the received infrared light into electric signal and provide the electric signal to the signal amplifier AMP1, the signal amplifier AMP1 can amplify the received electric signal and provide the amplified electric signal to the base of the triode Q1, the triode Q1 can output high level or low level to the processor U1 according to the amplified electric signal, the processor U1 can adjust the working state value of the infrared emission tube according to the high level or low level output by the triode Q1, the working state value can be a working voltage value or an input quantity control numerical value or a working current value of the infrared transmitting tube, so that the infrared photoelectric sensor is in a conducting state, the working state value of the infrared transmitting tube D2 in the conducting state is recorded as a conducting value, and a liquid level detection result of the height of the infrared photoelectric sensor is judged according to the conducting value.
Referring to fig. 6, a schematic flow chart of another liquid level detection method according to an embodiment of the invention is provided. As shown in fig. 6, this method embodiment includes the steps of:
s301, turning on an infrared photoelectric sensor.
Here, the specific implementation manner of step S301 may refer to the description of step S201 in the embodiment corresponding to fig. 4, and is not described herein again.
S302, adjusting the working voltage value of the infrared transmitting tube according to the received first level output by the infrared receiving head according to the infrared light intensity.
In a specific embodiment, the infrared receiving head is configured to output a first level or a second level according to the intensity of the received infrared light.
The infrared receiving head comprises a photosensitive diode, a signal amplifier and a triode, wherein:
the photodiode converts the received infrared light into an electric signal, the electric signal is amplified by the signal amplifier and then output to a base electrode of the triode, and the triode outputs the first level or the second level according to the electric signal received by the base electrode.
Wherein the first level and the second level may represent a low level and a high level, i.e. 0 and 1.
Specifically, a processor (such as a single chip microcomputer) in the liquid level detection device adjusts the working voltage of the infrared transmitting tube according to the level output by the infrared receiving head according to the intensity of the received infrared light. If the normal state of the infrared photoelectric sensor is low level and the level output by the infrared receiving head received by a processor (such as a singlechip) in the liquid level detection device is low level, increasing the working voltage value of the infrared transmitting tube; if the normal state of the infrared photoelectric sensor is low level and the level output by the infrared receiving head received by a processor (such as a singlechip) in the liquid level detection device is high level, the working voltage value of the infrared transmitting tube is reduced. If the normal state of the infrared photoelectric sensor is high level and the level output by the infrared receiving head received by a processor (such as a singlechip) in the liquid level detection device is high level, increasing the working voltage value of the infrared transmitting tube; if the normal state of the infrared photoelectric sensor is high level and the level output by the infrared receiving head received by a processor (such as a singlechip) in the liquid level detection device is low level, the working voltage value of the infrared transmitting tube is reduced.
For example, the photodiode in the infrared receiving head converts the light intensity of the infrared transmitting tube at 1.2V output voltage of a digital-to-analog converter in a processor (such as a single chip) in the liquid level detection device in step S301 into an 8uA current signal, that is, the photodiode converts the light intensity of the infrared transmitting tube at 1.2V operating voltage into an 8uA current signal and outputs the converted 8uA current signal to the signal amplifier, the signal amplifier outputs a 100-fold amplified 0.8mA current signal to the base of the triode NPN, and the collector of the triode NPN is biased but not conductive, so that the output level of the infrared receiving head is high, that is, the first level output by the infrared receiving head according to the received infrared light intensity is high. A processor (such as a singlechip) in the liquid level detection device increases the working voltage value of the infrared transmitting tube from 1.2V to 1.3V according to the high level output by the infrared receiving head.
S303, judging whether the output level of the infrared receiving head is changed from the first level to the second level.
The first level obtained according to step S302 is a high level, where the second level is a low level.
For example, the photodiode in the infrared receiver converts the light intensity of the infrared emitter at the operating voltage of 1.3V in step S302 into a 9uA current signal, and outputs the converted 9uA current signal to the signal amplifier, the signal amplifier outputs a 0.9mA current signal amplified by 100 times to the base of the NPN transistor, and the collector of the NPN transistor is biased forward but is not turned on, resulting in a high output level of the infrared receiver. A processor (such as a singlechip) in the liquid level detection device receives the high level output by the infrared receiving head, and a judgment result that the output level of the infrared receiving head is not changed from the high level to the low level is obtained. Step S302 is then performed.
For another example, the photodiode in the infrared receiving head converts the light emitting intensity of the infrared emitting tube at the working voltage of 1.5V in step S302 into a 10uA current signal, and outputs the converted 10uA current signal to the signal amplifier, the signal amplifier outputs the 1mA current signal amplified by 100 times to the base of the NPN triode, and the triode is turned on, so that the output level of the infrared receiving head is a low level. A processor (such as a singlechip) in the liquid level detection device receives the low level output by the infrared receiving head to obtain a judgment result that the output level of the infrared receiving head is changed from the high level to the low level. Step S304 is then performed.
S304, recording the working voltage value of the infrared transmitting tube as a conducting value when the output level of the infrared receiving head is changed from the first level to the second level.
Specifically, a processor (such as a single chip microcomputer) in the liquid level detection device records the working voltage of the infrared transmitting tube as a conduction value when the output level of the infrared receiving head is changed from a first level to a second level (the infrared photoelectric sensor is in a conduction state).
For example, the processor (e.g., a single chip microcomputer) in the liquid level detection device executes step S303 to obtain a determination result that the output level of the infrared receiving head changes from high level to low level, that is, the infrared photoelectric sensor (normally high) is in a conducting state, and records that the operating voltage of the infrared transmitting tube at this time is 1.5V, which is a conducting value.
S305, judging the liquid level detection result at the first height of the liquid container wall according to the conduction value.
Specifically, the liquid level detection device compares the conduction value with a preset working voltage range, and determines that liquid exists at the first height if the conduction value is not within the preset working voltage range, and determines that no liquid exists at the first height if the conduction value is within the preset working voltage range.
When air exists between the infrared transmitting tube and the infrared receiving head, a processor (such as a single chip microcomputer) in the liquid level detection device determines the working voltage range of the infrared transmitting tube according to a plurality of working voltage values of the infrared transmitting tube when the infrared photoelectric sensor is conducted for a plurality of times.
For example, when air exists between the infrared transmitting tube and the infrared receiving head, the processor (such as a single chip microcomputer) in the liquid level detecting device controls the value of the input digital quantity of the digital-to-analog converter to enable the digital-to-analog converter to output a 2.3V voltage signal to the input end of the voltage-to-current converter, the 2.3V voltage signal outputs 14mA of current to the infrared transmitting tube through the voltage-to-current converter to drive the infrared transmitting tube to work and emit infrared light, the photodiode in the infrared receiving head converts the received infrared light into a 9uA current signal and outputs the converted 9uA current signal to the signal amplifier, the signal amplifier outputs a 100 times amplified 0.9mA current signal to the base of the NPN triode, the collector of the NPN triode is biased but not conducted, so that the output level of the infrared receiving head is high level, the processor (such as a single chip microcomputer) in the liquid level detecting device receives the high level output by the infrared receiving head, and according to the high level output by the infrared receiving head, the output voltage of a digital-to-analog converter of the infrared transmitting tube in a processor (such as a single chip microcomputer) in the liquid level detection device is increased to 2.5V, namely, the working voltage value of the infrared transmitting tube is increased to 2.5V, the level output by the infrared receiving head received by the processor (such as the single chip microcomputer) in the liquid level detection device is changed from the high level to the low level, the infrared photoelectric sensor (normally high) is determined to be in a conducting state, and the working voltage 2.5V of the infrared transmitting tube at the moment is recorded as the conducting value of the infrared photoelectric sensor when air exists between the infrared transmitting tube and the infrared receiving head. By analogy, when a processor (such as a single chip microcomputer) in the liquid level detection device obtains that air exists between the infrared emission tube and the infrared receiving head, 10 working voltage values of the infrared emission tube are respectively 2.5V, 2.52V, 2.5V, 2.55V, 2.56V, 2.6V, 2.58, 2.54V, 2.51V and 2.5V when the infrared photoelectric sensor is conducted for 10 times, and the condition that the 2.5V-2.6V is the preset working voltage range of the infrared emission tube is determined.
For example, after the processor (e.g., a single chip) in the liquid level detection device executes step S304 to obtain the conduction value of 1.5V, the conduction value is compared with the preset operating voltage range of 2.5V to 2.6V, and it is obvious that the conduction value of 1.5V is not within the preset operating voltage range of 2.5V to 2.6V, and it is determined that the liquid exists at the first height.
For another example, if the liquid level detection device executes step S304 to obtain a conduction value of 2.5V, and compares the conduction value with the preset operating voltage range of 2.5V-2.6V, and it is obvious that the conduction value of 2.5V is within the preset operating voltage range of 2.5V-2.6V, it is determined that there is no liquid at the first height, i.e., there is air between the infrared transmitting tube and the infrared receiving head.
In another possible implementation manner, the liquid level detection device determines the type of the liquid in the liquid container according to the conduction value obtained by the current record and the relationship between the preset conduction value and the type of the liquid.
Specifically, a processor (e.g., a single chip) in the liquid level detection device may determine whether liquid exists at the first height according to the currently recorded conduction value and a preset conduction value table (as shown in table 1) of the infrared photoelectric sensor in different liquid types, and if liquid exists at the first height, may also determine the type of liquid in the liquid container.
For example, after the processor (e.g., a single chip) in the liquid level detection device executes step S304 to obtain the conduction value of 1.5V, the conduction value is matched with the conduction value table (shown in table 1) of the infrared photoelectric sensor in different preset liquid types, and it is determined that liquid exists at the first height and the type of liquid in the liquid container is C.
Because the liquid level detection result is determined by the working voltage value of the infrared transmitting tube when the infrared photoelectric sensor is in a conducting state, rather than directly probing the electrode into liquid, the influence of an oxide film on a detection circuit is avoided, and the liquid level can be accurately detected so as to improve the reliability of the liquid level detection result.
In addition, if the liquid is required to be detected at a plurality of positions, only the infrared photoelectric sensors are required to be arranged at the corresponding heights of the positions, and the operation is simple.
Referring to fig. 7, a schematic flow chart of another liquid level detection method according to an embodiment of the invention is provided. As shown in fig. 7, this method embodiment includes the steps of:
s401, turning on an infrared photoelectric sensor.
Here, the specific implementation manner of step S401 may refer to the description of step S301 in the embodiment corresponding to fig. 6, and is not described herein again.
S402, adjusting a control value according to a first level output by the infrared receiving head according to the received infrared light intensity.
The control value may be an input value of a digital-to-analog converter in a processor (such as a single chip) in the liquid level detection device, and is used for controlling the working voltage or the working current of the infrared emission tube.
Specifically, a processor (such as a single chip microcomputer) in the liquid level detection device adjusts an input quantity control value of the digital-to-analog converter according to the level output by the infrared receiving head according to the intensity of the received infrared light. If the normal state of the infrared photoelectric sensor is low level and the level output by the infrared receiving head received by a processor (such as a singlechip) in the liquid level detection device is low level, increasing the input quantity control value of the digital-to-analog converter; if the normal state of the infrared photoelectric sensor is low level and the level output by the infrared receiving head received by a processor (such as a singlechip) in the liquid level detection device is high level, the input quantity control value of the digital-to-analog converter is reduced. If the normal state of the infrared photoelectric sensor is high level and the level output by the infrared receiving head received by a processor (such as a singlechip) in the liquid level detection device is high level, increasing the input quantity control value of the digital-to-analog converter; if the normal state of the infrared photoelectric sensor is high level and the level output by the infrared receiving head received by a processor (such as a singlechip) in the liquid level detection device is low level, the input quantity control value of the digital-to-analog converter is reduced.
For example, the processor (e.g., a single chip microcomputer) converts the digital-to-analog converter input control value 200 used to turn on the infrared photoelectric sensor in step S401 into a 1.2V output voltage signal through a digital-to-analog converter, the 1.2V voltage signal outputs a 7mA current to the infrared emission tube through the voltage-to-current converter so as to change the intensity of the infrared light emitted by the infrared emission tube, the photodiode converts the received infrared light into an 8uA current signal and outputs the converted 8uA current signal to the signal amplifier, the signal amplifier outputs a 100-fold amplified 0.8mA current signal to the base of the NPN triode, and the triode is in an off state, so that the output level of the infrared receiver is high level, that is, the first level output by the infrared receiver according to the received infrared light intensity is high level. Because the infrared photoelectric sensor in the embodiment of the method is normally at a high level and the level output by the infrared receiving head is at a high level, a processor (such as a single chip microcomputer) in the liquid level detection device increases the input quantity control value of the digital-to-analog converter from 200 to 210.
And S403, judging whether the output level of the infrared receiving head is changed from the first level to the second level.
For example, the processor (e.g., a single chip microcomputer) converts the increased input quantity control value 210 obtained in step S402 into a 1.3V output voltage signal through a digital-to-analog converter, the 1.3V voltage signal outputs 8mA of current to the infrared emission tube through a voltage-to-current converter so as to change the intensity of infrared light emitted by the infrared emission tube, the photodiode converts the received infrared light into a 9uA current signal and outputs the converted 9uA current signal to a signal amplifier, the signal amplifier outputs a 100-fold amplified 0.9mA current signal to the base of an NPN transistor, the NPN transistor is in a cut-off state, so that the output level of the infrared receiver is a high level, and a determination result that the output level of the infrared receiver does not change from the high level to the low level is obtained according to the first level obtained in step S402. Step S402 is then performed.
For another example, the processor (e.g., a single chip microcomputer) converts the increased input quantity control value 400 obtained in step S402 into a 2.1V output voltage signal through a digital-to-analog converter, the 2.1V voltage signal outputs a current of 13mA to the infrared emission tube through a voltage-to-current converter so that the intensity of infrared light emitted by the infrared emission tube changes, the photodiode converts the received infrared light into a 14uA current signal and outputs the converted 14uA current signal to a signal amplifier, the signal amplifier outputs a current signal of 1.4mA amplified by 100 times to an NPN base of a triode, the triode is in a conducting state, so that the output level of the infrared receiver is a low level, and a determination result that the output level of the infrared receiver changes from the high level to the low level is obtained according to step S402, where the first level is a high level. Step S404 is then performed.
It is understood that if the output level of the infrared receiving head is not changed from the first level to the second level, step S402 is executed; if the output level of the infrared receiving head changes from the first level to the second level, step S404 is executed.
S404, adjusting the control value according to the received second level output by the infrared receiving head according to the infrared light intensity.
Specifically, when the normal state of the infrared photoelectric sensor is a high level, if a processor (such as a single chip microcomputer) in the liquid level detection device receives that a second level output by the infrared receiving head is a low level, an input quantity control numerical value in a digital-to-analog converter in the processor (such as the single chip microcomputer) in the device is reduced; if the second level received by the processor (such as a singlechip) in the liquid level detection device and output by the infrared receiving head is high level, the input quantity control value in a digital-to-analog converter in the processor (such as a singlechip) in the device is increased. When the normal state of the infrared photoelectric sensor is low level, if a processor (such as a singlechip) in the liquid level detection device receives that the second level output by the infrared receiving head is high level, reducing an input quantity control value in a digital-to-analog converter in the processor (such as the singlechip) in the device; if the second level received by the processor (such as a singlechip) in the liquid level detection device and output by the infrared receiving head is low level, the input quantity control value in a digital-to-analog converter in the processor (such as a singlechip) in the device is increased.
If the normal state of the infrared photoelectric sensor is high level, and the judgment result obtained in step S403 that the output level of the infrared receiving head changes from the first level to the second level corresponds to the situation that the processor (such as a single chip microcomputer) in the liquid level detection device increases the input amount control value of the digital-to-analog converter to 410 so that the digital-to-analog converter outputs a 2.5V voltage signal to the input end of the voltage-to-current converter, the 2.5V voltage signal passes through the voltage-to-current converter to output a 14mA current to the infrared transmitting tube so that the output level of the infrared receiving head changes from high level to low level, the liquid level detection device reduces the input quantity control value of the digital-to-analog converter to 400 according to the low level output by the infrared receiving head, so that the digital-to-analog converter outputs a 2.1V voltage signal to the input end of the voltage-current converter, and the 2.1V voltage signal outputs a 13mA current to the infrared transmitting tube through the voltage-current converter. Step S405 is then performed.
S405, judging whether the output level of the infrared receiving head is changed from the second level to the first level.
For example, the photodiode in the infrared receiving head converts the received light intensity of the infrared transmitting tube at the working current of 13mA in step S404 into a 14uA current signal, and outputs the converted 14uA current signal to the signal amplifier, the signal amplifier outputs the current signal of 1.4mA amplified by 100 times to the base of the NPN transistor, and the transistor is turned on, resulting in that the output level of the infrared receiving head is at a low level. A processor (such as a singlechip) in the liquid level detection device receives the low level output by the infrared receiving head to obtain the judgment result that the output level of the infrared receiving head is not changed from the low level to the high level, step S404 is executed to continue to reduce the input control value of the digital-to-analog converter to 390 so that the digital-to-analog converter outputs a 2.0V voltage signal to the input terminal of the voltage-to-current converter, the 2.0V voltage signal outputs a 12mA current to the infrared emission tube through the voltage-to-current converter, the intensity of the infrared light emitted by the infrared emission tube changes, the photodiode converts the received infrared light into a 9uA current signal, and the converted 9uA current signal is output to a signal amplifier, the signal amplifier outputs a 0.9mA current signal amplified by 100 times to a base electrode of an NPN triode, and the triode is in a cut-off state, so that the output level of the infrared receiving head is high level. A processor (such as a singlechip) in the liquid level detection device receives the high level output by the infrared receiving head to obtain a judgment result that the output level of the infrared receiving head is changed from low level to high level. Step S406 is then performed.
S406, recording the average value of the plurality of control values between the first time and the second time as a conduction value.
In a specific embodiment, the liquid level detection device determines the output level of the infrared receiving head to be a first time when the output level changes from the first level to the second level.
The liquid level detection means determines a timing when the output level of the infrared receiving head changes from the second level to the first level as a second timing.
Specifically, a processor (such as a single chip microcomputer) in the liquid level detection device determines the time when the output level of the infrared receiving head changes from a first level to a second level as a first time, determines the time when the output level of the infrared receiving head changes from the second level to the first level as a second time, calculates an average value of a plurality of control values between the first time and the second time including the first time, and records the average value as a conduction value.
For example, the processor (e.g., a single chip microcomputer) in the liquid level detection device determines a time at which the output level of the infrared receiving head changes from high level to low level in step S403 as a first time at which the control value is 410, determines a time at which the output level of the infrared receiving head changes from low level to high level in step S405 as a second time at which the control value is 390, and calculates an average value of a plurality of control values 410 and 400 between the first time including the first time and the second time as 405, and records 405 as the on value.
S407, judging a liquid level detection result at the first height of the liquid container wall according to the conduction value.
Specifically, the liquid level detection device compares the conduction value with a preset control value range, and determines that liquid exists at the first height if the conduction value is not within the preset control value range, and determines that no liquid exists at the first height if the conduction value is within the preset control value range.
When air exists between the infrared transmitting tube and the infrared receiving head, a processor (such as a single chip microcomputer) in the liquid level detection device controls the control value range determined by a plurality of input quantity control values of a digital-to-analog converter in the processor (such as the single chip microcomputer) in the liquid level detection device when the infrared photoelectric sensor is conducted for a plurality of times.
For example, if the infrared photoelectric sensor is normally at a high level, when air exists between the infrared transmitting tube and the infrared receiving head, the processor (e.g., a single chip microcomputer) in the liquid level detection device controls the input quantity of the digital-to-analog converter to be 710, so that the digital-to-analog converter outputs a 2.6V voltage signal to the input end of the voltage-to-current converter, the 2.6V voltage signal outputs 16mA of current to the infrared transmitting tube through the voltage-to-current converter to drive the infrared transmitting tube to work to emit infrared light, the photodiode in the infrared receiving head converts the received infrared light into a 1.1uA current signal and outputs the converted 1.1uA current signal to the signal amplifier, the signal amplifier outputs the 100 times amplified 1.1mA current signal to the base of the NPN triode, the triode is in a conducting state, so that the output level of the infrared receiving head is at a low level, and at this time, the level output by the infrared receiving head received by the processor (e.g., the single chip microcomputer Low level and this time is denoted as the first time. The processor (such as a singlechip) in the liquid level detection device reduces the input quantity control value of the digital-to-analog converter to 700 according to the low level output by the infrared receiving head so that the digital-to-analog converter outputs a 2.5V voltage signal to the input end of the voltage-current converter, the 2.5V voltage signal outputs 15mA current to the infrared transmitting tube through the voltage-current converter, the photodiode in the infrared receiving head converts the received infrared light into a 1.0uA current signal and outputs the converted 1.0uA current signal to the signal amplifier, the signal amplifier outputs the 1.0mA current signal amplified by 100 times to the base electrode of the NPN triode, the triode is in a conducting state so that the output level of the infrared receiving head is low level, the processor (such as the singlechip) in the liquid level detection device reduces the input quantity control value of the digital-to 690 according to the low level output by the infrared receiving head so that the digital-to enable the digital-to output a 2.4V voltage signal to the input end, a voltage signal of 2.4V outputs a current of 14mA to an infrared transmitting tube through a voltage-current converter, a photodiode in an infrared receiving head converts received infrared light into a current signal of 0.9uA, and outputs the converted current signal of 0.9uA to a signal amplifier, the signal amplifier outputs a current signal of 0.9mA amplified by 100 times to a base of an NPN triode, the triode is in an off state, at this time, a level output by the infrared receiving head received by a processor (such as a single chip microcomputer) in a liquid level detection device changes from a low level to a high level, it is determined that an infrared photoelectric sensor is in the off state, the infrared photoelectric sensor is recorded as a second time at this time, an average value of a plurality of control values 710 and 700 between a first time including the first time and the second time is calculated as 705, and the 705 is recorded as an on value. By analogy, when a processor (such as a single chip microcomputer) in the liquid level detection device obtains that air exists between the infrared transmitting tube and the infrared receiving head, when the infrared photoelectric sensor is conducted for 10 times, a plurality of input quantity control values in a digital-to-analog converter in the liquid level detection device are 700, 702, 708, 705, 710, 706, 701, 709, 703 and 710 respectively, and 700 plus 710 is determined as a preset control value range of the input quantity of the digital-to-analog converter in the liquid level detection device.
For example, after the processor (e.g., a single chip) in the liquid level detection device executes step S406 to obtain the conduction value 405, the conduction value 405 is compared with the preset control value range 700 and 710, and it is obvious that the conduction value 405 is not within the preset control value range 700 and 710, it is determined that the liquid exists at the first height.
In another possible implementation manner, the liquid level detection device determines the type of the liquid in the liquid container according to the conduction value obtained by the current record and the relationship between the preset conduction value and the type of the liquid.
Specifically, a processor (e.g., a single chip) in the liquid level detection device may determine whether liquid exists at the first height according to the currently recorded conduction value and a preset conduction value table (as shown in table 1) of the infrared photoelectric sensor in different liquid types, and if liquid exists at the first height, may also determine the type of liquid in the liquid container.
For example, after the processor (e.g., a single chip) in the liquid level detection device executes step S406 to obtain the conduction value 405, the conduction value is matched with a preset conduction value table (shown in table 1) of the infrared photoelectric sensor in different liquid types, and it is determined that liquid exists at the first height and the type of the liquid in the liquid container is D.
Because the liquid level detection result is determined by the average value of the input quantity control values of the corresponding digital-to-analog converters when the infrared photoelectric sensor is in a conducting state, rather than directly probing the electrodes into the liquid, the influence of an oxide film on a detection circuit is avoided, and the liquid level can be accurately detected so as to improve the reliability of the liquid level detection result.
It should be noted that the operating state values in the embodiments corresponding to fig. 4, fig. 6, and fig. 7 may be replaced with each other, and correspondingly, the manners of turning on the infrared photoelectric sensor and adjusting the operating state value of the infrared transmitting tube may also be adaptively replaced, and the replaced technical solutions also belong to the protection scope of the embodiments of the present invention.
In the method and the apparatus according to the embodiment of the present invention described above, the liquid level detection device 800 includes an infrared photoelectric sensor, the infrared photoelectric sensor includes an infrared transmitting tube and an infrared receiving head, the infrared transmitting tube and the infrared receiving head are respectively located at different positions of a first height of a liquid container wall, the infrared transmitting tube is used for emitting infrared light to the infrared receiving head, and the infrared receiving head is used for adjusting a conducting state of the infrared photoelectric sensor according to the infrared light;
referring to fig. 8, a schematic structural diagram of a liquid level detection device according to an embodiment of the present invention is provided, where the liquid level detection device is a liquid level detection device or a part of a liquid level detection device. As shown in fig. 8, the liquid level detection apparatus further includes an activation unit 801, an adjustment unit 802, a recording unit 803, and a judgment unit 804.
A starting unit 801 for turning on the infrared photoelectric sensor;
in one possible implementation, the starting unit 801 may include an analog-to-digital converter and an output power tube, wherein an output terminal of the analog-to-digital converter is connected to a base terminal of the output power tube.
Specifically, the starting unit 801 may output a voltage value through an input digital value of the analog-to-digital converter, and output the output voltage value to a base of the output power tube, where the base of the output power tube outputs a current to the infrared emitting tube according to the output voltage value, so as to drive the infrared emitting tube to emit infrared light, and the infrared receiving head receives the infrared light emitted by the infrared emitting tube.
An adjusting unit 802, configured to adjust a working state value of the infrared transmitting tube, so as to adjust intensity of infrared light emitted by the infrared transmitting tube;
specifically, the adjusting unit 802 adjusts the operating state value of the infrared transmitting tube according to the intensity of the infrared light received by the infrared receiving head. If the intensity of the infrared light received by the infrared receiving head is smaller than the minimum luminous intensity in the preset luminous intensity range, the working state value of the infrared transmitting tube is increased; and if the intensity of the infrared light received by the infrared receiving head is greater than the maximum luminous intensity in the preset luminous intensity range, reducing the working state value of the infrared transmitting tube.
Specifically, the infrared receiving head comprises a photodiode, a signal amplifier and a triode, and the photodiode converts the received infrared light into an electric signal.
A recording unit 803, configured to record a working state value of the infrared emission tube as a conduction value when the infrared light intensity is within a preset light emission intensity range;
a determining unit 804, configured to determine a liquid level detection result at the first height of the liquid container wall according to the conduction value. Optionally, the adjusting unit 802 includes an operating state value adjusting subunit 8021 and a determining subunit 8022, where:
optionally, the working state value adjusting subunit 8021 is configured to adjust the working state value of the infrared transmitting tube according to the first level output by the infrared receiving head. The infrared receiving head is used for outputting a first level or a second level according to the infrared light intensity so as to adjust the conduction state of the infrared photoelectric sensor. The infrared receiving head comprises a photosensitive diode, a signal amplifier and a triode, wherein the photosensitive diode converts received infrared light into an electric signal, the electric signal is amplified by the signal amplifier and then output to a base of the triode, and the triode outputs the first level or the second level according to the electric signal received by the base.
Specifically, the operating state value adjusting subunit 8021 adjusts the operating state value of the infrared transmitting tube according to the level output by the infrared receiving head according to the received infrared light intensity. If the level received by the processor and output by the infrared receiving head is a low level, increasing the working state value of the infrared transmitting tube; and if the level received by the processor and output by the infrared receiving head is a high level, reducing the working state value of the infrared transmitting tube.
Optionally, the determining subunit 8022 is configured to determine that the infrared light intensity is within the preset light-emitting intensity range when the output level of the infrared receiving head changes from the first level to the second level.
Optionally, the apparatus further comprises:
a working state value adjusting unit 805, configured to adjust a working state value of the infrared transmitting tube according to the second level output by the infrared receiving head until the output level of the infrared receiving head changes from the second level to the first level;
optionally, the recording unit 803 is configured to record an average value of a plurality of operating state values of the infrared transmitting tube between a first time and a second time as the conduction value, where the first time is a time when the output level of the infrared receiving head changes from the first level to the second level, and the second time is a time when the output level of the infrared receiving head changes from the second level to the first level.
Optionally, the determining unit 804 is configured to determine that liquid exists at the first height of the liquid container wall if the conduction value is not within the preset working state range, where the preset working state range is a corresponding working state range when air exists at the first height and the infrared photoelectric sensor is conducted by adjusting the working state value of the infrared transmitting tube; and if the conduction value is within the preset working state range, determining that no liquid exists at the first height of the liquid container wall.
Optionally, the determining unit 803 is further configured to, when it is determined that liquid exists at the first height of the liquid container wall, determine a liquid type in the liquid container according to the currently recorded conduction value and a relationship between a preset conduction value and the liquid type.
Specifically, in the case that the determination unit 803 determines that the liquid is present at the first height of the wall of the liquid container, the type of the liquid in the liquid container may be determined according to the currently recorded conduction value and a preset conduction value table (as shown in table 1) of the infrared photoelectric sensor in different types of the liquid.
Because the liquid level detection result is determined by the conduction value of the infrared photoelectric sensor, rather than directly probing the electrode into the liquid, the influence of an oxide film on a detection circuit is avoided, and the liquid level can be accurately detected, so that the reliability of the liquid level detection result is improved.
Referring again to fig. 3, as shown in fig. 3, the liquid level detection device comprises a processor 301 and an infrared photosensor 302, wherein the photosensor comprises an infrared emission tube 3021 and an infrared receiving head 3022, and the infrared emission tube 3021 and the infrared receiving head 3022 are respectively positioned at different positions of a first height of the wall of the liquid container;
the infrared transmitting tube 3021 is connected to the processor 301, and is configured to emit infrared light to the infrared receiving head 3022;
the infrared receiving head 3022 is connected to the processor 301, and is configured to receive infrared light emitted by the infrared emitting tube 3021 and adjust a conduction state of the infrared photoelectric sensor according to the infrared light;
the processor 301 is configured to adjust an operating state value of the infrared emission tube 3021, so as to adjust intensity of infrared light emitted from the infrared emission tube 3021, record the operating state value of the infrared emission tube 3021 as a conduction value of the infrared photoelectric sensor 302 when the intensity of infrared light is within a preset light emission intensity range, and determine a liquid level detection result of the first height of the liquid container wall according to the conduction value.
Optionally, the infrared receiving head 3022 is configured to output a first level or a second level according to the received intensity of the infrared light, so as to adjust the on state of the infrared photoelectric sensor 302;
the processor 301 is further configured to adjust an operating state value of the infrared transmitting tube 3021 according to the first level, and when the first level changes to the second level, determine that the intensity of the infrared light received by the infrared receiving head 3022 is within the preset luminous intensity range. Optionally, the processor 301 is configured to determine that liquid exists at the first height if the conduction value is not within the preset working state range, where the preset working state range is a corresponding working state range when air exists at the first height and the working state value of the infrared emission tube 3021 is adjusted to turn on the infrared photoelectric sensor 302; and if the conduction value is within the preset working state range, determining that no liquid exists at the first height of the liquid container wall.
Optionally, the processor 301 is further configured to determine a liquid type in the liquid container according to the currently recorded conduction value and a preset relationship between the conduction value and the liquid type when it is determined that the liquid is present at the first height of the wall of the liquid container.
The photodiode D1 and the comparator COMP1 may be integrated in the infrared receiving head 3022, and the output terminal of the infrared receiving head 3022 is connected to the input terminal of the processor 301, wherein the ground terminal of the infrared receiving head 3022 is grounded.
Specifically, the Processor 301 includes, but is not limited to, a Central Processing Unit (CPU), an embedded Microcontroller (MCU), an embedded Microprocessor (MPU), and an embedded System on Chip (SoC).
Referring to fig. 5, a schematic diagram of another liquid level detecting device according to an embodiment of the present invention is provided. As shown in FIG. 5, the liquid level detection device comprises a processor 501 and an infrared photoelectric sensor 502, wherein the photoelectric sensor comprises an infrared transmitting tube 5021 and an infrared receiving head 5022, and the infrared transmitting tube 5021 and the infrared receiving head 5022 are respectively positioned at different positions of a first height of the wall of a liquid container;
the infrared transmitting tube 5021 is connected with the processor 501 and is used for emitting infrared light to the infrared receiving head 5022;
the infrared receiving head 5022 is connected with the processor 501 and is used for receiving infrared light emitted by the infrared emitting tube 5021 and adjusting the conduction state of the infrared photoelectric sensor 502 according to the infrared light;
the processor 501 is configured to adjust a working state value of the infrared transmitting tube 5021, to adjust intensity of infrared light emitted by the infrared transmitting tube 5021, record the working state value of the infrared transmitting tube 5021 as a conduction value of the infrared photoelectric sensor 502 when the intensity of the infrared light is within a preset light emitting intensity range, and determine a liquid level detection result of the first height of the liquid container wall according to the conduction value.
Optionally, the infrared receiving head 5022 is configured to output a first level or a second level according to the received infrared light intensity, so as to adjust the on state of the infrared photoelectric sensor 502.
The processor 501 is further configured to adjust an operating state value of the infrared transmitting tube 5021 according to the first level, and when the first level changes to the second level, it is determined that the intensity of the infrared light received by the infrared receiving head 5022 is within the preset light intensity range.
Optionally, the processor 501 is further configured to adjust the operating state value of the infrared transmitting tube 5021 according to the second level output by the infrared receiving head 5022 until the output level of the infrared receiving head 5022 changes from the second level to the first level;
the processor 501 is further configured to record an average value of a plurality of operating state values of the infrared transmitting tube 5021 as the conducting value between a first time when the output level of the infrared receiving head 5022 changes from the first level to the second level and a second time when the output level of the infrared receiving head 5022 changes from the second level to the first level.
Optionally, the infrared receiving head 5022 includes a photodiode D1, a signal amplifier AMP1 and a transistor Q1, wherein:
the photodiode D1 is connected to the signal amplifier AMP1, and is used for converting the received infrared light into an electrical signal.
The signal amplifier AMP1 is connected to the transistor Q1, and is used for amplifying the electrical signal and outputting the amplified electrical signal to the base of the transistor Q1.
The transistor Q1 is connected to the processor U1, and is configured to output the first level or the second level according to an electrical signal received by the base.
Optionally, the processor 501 is configured to determine that liquid exists at the first height if the conduction value is not within the preset working state range, where the preset working state range is a corresponding working state range when air exists at the first height and the working state value of the infrared transmitting tube 5021 is adjusted to turn on the infrared photoelectric sensor 702; and if the conduction value is within the preset working state range, determining that no liquid exists at the first height of the liquid container wall.
Optionally, the processor 501 is further configured to determine a liquid type in the liquid container according to the currently recorded conduction value and a preset relationship between the conduction value and the liquid type when it is determined that the liquid is present at the first height of the wall of the liquid container.
In a possible implementation manner, referring to fig. 5, the photodiode D1, the signal amplifier AMP1, and the transistor Q1 in the infrared receiving tube may be integrated into a same photoelectric conversion amplifying element, an output terminal of the photoelectric conversion amplifying element is connected to a base of the transistor Q1, a ground terminal of the photoelectric conversion amplifying element and an emitter of the transistor Q1 are both grounded, and R1 between the power source VCC and the collector is to prevent a short circuit between VCC and GND.
Specifically, the Processor 501 includes, but is not limited to, a Central Processing Unit (CPU), an embedded Microcontroller (MCU), an embedded Microprocessor (MPU), and an embedded System on Chip (SoC).
The terms "first," "second," "third," and "fourth," etc. in the description and claims of this application and in the accompanying drawings are used for distinguishing between different objects and not for describing a particular order. Furthermore, the terms "include" and "have," as well as any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus.
In the present application, "a and/or B" means one of the following cases: a, B, A and B. "at least one of … …" refers to any combination of the listed items or any number of the listed items, e.g., "at least one of A, B and C" refers to one of: any one of seven cases, a, B, C, a and B, B and C, a and C, A, B and C.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program, which can be stored in a computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. The storage medium may be a magnetic disk, an optical disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), or the like.
The method and the related apparatus provided by the embodiment of the present invention are described with reference to the method flowchart and/or the structural diagram provided by the embodiment of the present invention, and each flow and/or block of the method flowchart and/or the structural diagram, and the combination of the flow and/or block in the flowchart and/or the block diagram can be specifically implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block or blocks of the block diagram. These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block or blocks of the block diagram. These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block or blocks.
The above disclosure is only for the purpose of illustrating the preferred embodiments of the present invention, and it is therefore to be understood that the invention is not limited by the scope of the appended claims.

Claims (10)

1. The liquid level detection method is applied to liquid level detection equipment, the liquid level detection equipment comprises an infrared photoelectric sensor, the infrared photoelectric sensor comprises an infrared transmitting tube and an infrared receiving head, the infrared transmitting tube and the infrared receiving head are respectively positioned at different positions of a first height of a liquid container wall, the infrared transmitting tube is used for emitting infrared light to the infrared receiving head, and the infrared receiving head is used for adjusting the conduction state of the infrared photoelectric sensor according to the infrared light;
the method comprises the following steps:
turning on the infrared photoelectric sensor;
adjusting the working state value of the infrared emission tube to adjust the intensity of infrared light emitted by the infrared emission tube;
recording the working state value of the infrared transmitting tube as the conduction value of the infrared photoelectric sensor when the infrared light intensity is within a preset light-emitting intensity range;
and judging the liquid level detection result at the first height of the liquid container wall according to the conduction value.
2. The method according to claim 1, wherein the infrared receiving head is used for outputting a first level or a second level according to the infrared light intensity to adjust the conduction state of the infrared photoelectric sensor;
the adjusting of the working state value of the infrared emission tube comprises:
adjusting the working state value of the infrared transmitting tube according to the first level output by the infrared receiving head;
when the output level of the infrared receiving head is changed from the first level to the second level, the infrared light intensity is determined to be within the preset luminous intensity range.
3. The method of claim 2, wherein determining that the infrared light intensity is within the preset light emission intensity range when the output level of the infrared receiving head changes from the first level to the second level further comprises:
adjusting the working state value of the infrared transmitting tube according to the second level output by the infrared receiving head until the output level of the infrared receiving head is changed from the second level to the first level;
the recording of the working state value of the infrared emission tube as a conduction value when the infrared light intensity is within a preset light intensity range comprises:
and recording the average value of a plurality of working state values of the infrared transmitting tube between a first moment and a second moment as the conduction value, wherein the first moment is the moment when the output level of the infrared receiving head is changed from the first level to the second level, and the second moment is the moment when the output level of the infrared receiving head is changed from the second level to the first level.
4. The method of claim 2, wherein the infrared receiving head comprises a photodiode, a signal amplifier, and a transistor, wherein:
the photodiode converts the received infrared light into an electric signal, the electric signal is amplified by the signal amplifier and then output to a base electrode of the triode, and the triode outputs the first level or the second level according to the electric signal received by the base electrode.
5. The method of claim 1, wherein said determining a liquid level detection result at said first height of said liquid container wall from said conduction value comprises:
if the conduction value is not within the preset working state range, determining that liquid exists at the first height of the wall of the liquid container, wherein the preset working state range is a corresponding working state range when the infrared photoelectric sensor is conducted by adjusting the working state value of the infrared emission tube when air exists at the first height;
and if the conduction value is within the preset working state range, determining that no liquid exists at the first height of the liquid container wall.
6. The method of any of claims 1-5, wherein said determining a level detection result at said first height of said liquid container wall from said conduction value further comprises:
and under the condition that the liquid is determined to exist at the first height of the wall of the liquid container, determining the type of the liquid in the liquid container according to the currently recorded conduction value and the relation between the preset conduction value and the type of the liquid.
7. The liquid level detection device is characterized by comprising an infrared photoelectric sensor, wherein the infrared photoelectric sensor comprises an infrared transmitting tube and an infrared receiving head, the infrared transmitting tube and the infrared receiving head are respectively positioned at different positions of a first height of a liquid container wall, the infrared transmitting tube is used for emitting infrared light to the infrared receiving head, and the infrared receiving head is used for adjusting the conduction state of the infrared photoelectric sensor according to the infrared light;
the device further comprises:
the starting unit is used for starting the infrared photoelectric sensor;
the adjusting unit is used for adjusting the working state value of the infrared transmitting tube so as to adjust the intensity of the infrared light emitted by the infrared transmitting tube;
the recording unit is used for recording the working state value of the infrared emission tube as a conduction value when the infrared light intensity is within a preset light intensity range;
and the judging unit is used for judging the liquid level detection result at the first height of the liquid container wall according to the conduction value.
8. The liquid level detection device is characterized by comprising a processor and an infrared photoelectric sensor, wherein the photoelectric sensor comprises an infrared transmitting tube and an infrared receiving head, and the infrared transmitting tube and the infrared receiving head are respectively positioned at different positions of a first height of a liquid container wall;
the infrared transmitting tube is connected with the processor and is used for emitting infrared light to the infrared receiving hair;
the infrared receiving head is connected with the processor and used for receiving infrared light emitted by the infrared emitting tube and adjusting the conduction state of the infrared photoelectric sensor according to the infrared light;
the processor is used for adjusting the working state value of the infrared emission tube so as to adjust the intensity of infrared light emitted by the infrared emission tube, recording the working state value of the infrared emission tube as the conduction value of the infrared photoelectric sensor when the intensity of the infrared light is within a preset luminous intensity range, and judging the liquid level detection result of the first height of the wall of the liquid container according to the conduction value.
9. The liquid level detection device according to claim 8, wherein the infrared receiving head is configured to output a first level or a second level according to the intensity of the received infrared light to adjust a conduction state of the infrared photoelectric sensor;
the processor is further configured to adjust a working state value of the infrared transmitting tube according to the first level, and when the first level changes to the second level, it is determined that the intensity of the infrared light received by the infrared receiving head is within the preset light-emitting intensity range.
10. The fluid level sensing device of claim 8, wherein the processor is further configured to:
adjusting the working state value of the infrared transmitting tube according to the second level output by the infrared receiving head until the output level of the infrared receiving head is changed from the second level to the first level;
and recording the average value of a plurality of working state values of the infrared transmitting tube between a first moment and a second moment as the conduction value, wherein the first moment is the moment when the output level of the infrared receiving head is changed from the first level to the second level, and the second moment is the moment when the output level of the infrared receiving head is changed from the second level to the first level.
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