Infrared detection liquid level circuit

Abstract

The embodiment of the utility model discloses an infrared detection liquid level circuit. The infrared detection liquid level circuit comprises an infrared receiving module, a signal processing module and a signal output module, the infrared receiving module comprises a field effect transistor and an infrared sensor, the field effect transistor comprises a first input end and a first output end, the first input end is connected with a signal input end, the signal input end is used for inputting an adjusting signal, the adjusting signal is used for adjusting opening or closing of the field effect transistor, and the infrared sensor comprises a transmitting end and a receiving end. The first output end is connected with the transmitting end; the signal processing module comprises an operational amplifier, the operational amplifier comprises a second input end and a second output end, the receiving end is connected with the second input end, and the second output end is connected with the signal output module; and the signal output module is used for outputting infrared detection liquid level voltage.

Description

Technical Field

[0001] This manual relates to the field of electronic medical devices, and in particular to an infrared liquid level detection circuit. Background Technology

[0002] With the continuous improvement of industrial automation, liquid level detection technology plays a crucial role in the production process. Infrared liquid level detection circuits, as a commonly used method, are widely used in various fields such as respiratory therapy due to their advantages of simple installation, accurate detection, and fast response. Respiratory therapy equipment is medical equipment used to treat and assist respiratory diseases, playing a vital role in the medical field. It primarily provides patients with a humidified and heated treatment environment to improve their respiratory status and enhance their comfort. Currently, respiratory therapy equipment generally includes a main unit and a humidifier. The gas generated by the main unit flows into the humidifier, where it is humidified. The humidified gas then flows to the patient through the breathing tubing. To improve the patient's experience, a liquid level detection device is usually installed in the main unit to monitor the liquid level inside the humidifier, preventing dry burning due to excessively low liquid levels or liquid overflow due to excessively high liquid levels.

[0003] Existing infrared liquid level detection circuits mainly include an infrared receiving module, a signal processing module, and a signal output module. The infrared receiving module is responsible for receiving signals from the infrared sensor, the signal processing module amplifies and filters the signals, and the signal output module converts the processed signals into corresponding voltage outputs to reflect the liquid level.

[0004] In existing infrared liquid level detection circuits, the infrared sensor signal is easily interfered with by various factors, resulting in unstable detection signals and affecting the accurate detection of liquid levels. Utility Model Content

[0005] This application provides an infrared liquid level detection circuit to solve the technical problems mentioned in the background art.

[0006] The embodiments of this application adopt the following technical solutions:

[0007] This application provides an infrared liquid level detection circuit, which includes: an infrared receiving module, a signal processing module, and a signal output module.

[0008] The infrared receiving module includes a field-effect transistor and an infrared sensor. The field-effect transistor includes a first input terminal and a first output terminal. The first input terminal is connected to a signal input terminal, which is used to input an adjustment signal. The adjustment signal is used to adjust the opening or closing of the field-effect transistor. The infrared sensor includes a transmitting terminal and a receiving terminal, and the first output terminal is connected to the transmitting terminal.

[0009] The signal processing module includes an operational amplifier, which includes a second input terminal and a second output terminal. The receiving terminal is connected to the second input terminal, and the second output terminal is connected to the signal output module.

[0010] The signal output module is used to output the infrared detection liquid level voltage.

[0011] Furthermore, the field-effect transistor is an N-type metal-oxide-semiconductor transistor.

[0012] Furthermore, the adjustment signal is a pulse width modulation signal.

[0013] Furthermore, the infrared receiving module also includes a first resistor, a second resistor, and a first capacitor. The transmitting end includes a first transmitting end and a second transmitting end, and the receiving end includes a first receiving end and a second receiving end. The first end of the first capacitor is connected to the first input end and the signal input end, and the second end of the first capacitor is grounded. The first end of the first resistor is connected to a 5V power supply, and the second end of the first resistor is connected to the first receiving end and the second input end. The first end of the second resistor is connected to a 5V power supply, and the second end of the second resistor is connected to the second transmitting end. The first output end is connected to the first transmitting end, the second receiving end is grounded, and the first receiving end is connected to the second input end.

[0014] Furthermore, the second input terminal includes a non-inverting input terminal and an inverting input terminal; the second end of the first resistor is connected to the non-inverting input terminal, the first receiving terminal is connected to the non-inverting input terminal, and the inverting input terminal is connected to the second output terminal.

[0015] Furthermore, the signal processing module also includes a second capacitor, a third resistor, and a fourth resistor; the operational amplifier also includes a first interface and a second interface, the first interface being connected to a 5V power supply, the second interface being grounded, the first end of the second capacitor being connected to the 5V power supply and the first interface, the second end of the second capacitor being grounded, the first end of the third resistor being connected to the second output terminal, the second end of the third resistor being connected to the first end of the fourth resistor and the signal output module, the first end of the fourth resistor being connected to the signal output module, and the second end of the fourth resistor being grounded.

[0016] The above-mentioned technical solutions adopted in the application embodiments can achieve the following beneficial effects:

[0017] This application embodiment introduces a combination of a field-effect transistor (FET) and an infrared sensor. By adjusting the switching on and off of the FET, the infrared liquid level detection circuit can effectively reduce the influence of ambient light and other factors on the signal, thereby improving the stability of the detection signal. Simultaneously, the operational amplifier in the signal processing module can precisely amplify and filter the received signal, ensuring that the output liquid level voltage accurately reflects the actual liquid level, thus improving detection accuracy. When used in a ventilator, this infrared liquid level detection circuit can accurately detect the liquid level in the humidifier tank, preventing dry burning due to excessively low liquid levels or liquid overflow from the humidifier due to excessively high liquid levels. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments or prior art, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. (See attached drawings.)

[0019] In the picture:

[0020] Figure 1 This is a schematic diagram of the infrared liquid level detection circuit provided in the embodiments of this application;

[0021] Figure 2 This is a schematic diagram of the specific structure of the infrared liquid level detection circuit provided in the embodiments of this application. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0023] Example: Infrared liquid level detection circuit.

[0024] See appendix Figure 1 The schematic diagram shown is of an infrared liquid level detection circuit. The infrared liquid level detection circuit includes an infrared receiving module, a signal processing module, and a signal output module. This infrared liquid level detection circuit is used in humidifiers in hospitals.

[0025] In this embodiment, the infrared receiving module includes a field-effect transistor (FET) and an infrared sensor. The FET includes a first input terminal and a first output terminal. The first input terminal is connected to a signal input terminal, which is used to input an adjustment signal. The adjustment signal is used to adjust the FET to turn on or off. The infrared sensor includes a transmitter and a receiver, and the first output terminal is connected to the transmitter.

[0026] In this embodiment, the signal processing module includes an operational amplifier, which has a second input terminal and a second output terminal. The receiving terminal is connected to the second input terminal, and the second output terminal is connected to the signal output module.

[0027] In this embodiment, the signal output module is used to output the infrared detection liquid level voltage.

[0028] Furthermore, the field-effect transistor is an N-type metal-oxide-semiconductor transistor (NMOS).

[0029] Furthermore, the adjustment signal is a pulse width modulation (PWM) signal.

[0030] Further, see Figure 2 The schematic diagram of the infrared liquid level detection circuit shown includes an infrared receiving module that also includes a first resistor R1, a second resistor R2, and a first capacitor C3. The transmitting end of the infrared sensor W1 includes a first transmitting end 1 and a second transmitting end 2, and the receiving end of the infrared sensor W1 includes a first receiving end 3 and a second receiving end 4. The first end of the first capacitor C3 is connected to the first input end and the signal input end of the field-effect transistor Q1, and the second end of the first capacitor C3 is grounded. The first end of the first resistor R1 is connected to a 5V power supply, and the second end of the first resistor R1 is connected to the first receiving end 3 and the second input end of the operational amplifier U1A. The first end of the second resistor R2 is connected to a 5V power supply, and the second end of the second resistor R2 is connected to the second transmitting end 2. The first output end is connected to the first transmitting end 1, the second receiving end 4 is grounded, and the first receiving end 3 is connected to the second input end.

[0031] Furthermore, the second input terminal includes a non-inverting input terminal 3 and an inverting input terminal 2; the second end of the first resistor R1 is connected to the non-inverting input terminal 3, the first receiving terminal 3 is connected to the non-inverting input terminal 3, and the inverting input terminal 2 is connected to the second output terminal 1.

[0032] Furthermore, the signal processing module also includes a second capacitor C1, a third resistor R3, and a fourth resistor R4; the operational amplifier U1A also includes a first interface 8 and a second interface 4. The first interface 8 is connected to a 5V power supply, and the second interface 4 is grounded. The first end of the second capacitor C1 is connected to the 5V power supply and the first interface 8, and the second end of the second capacitor C1 is grounded. The first end of the third resistor R3 is connected to the second output terminal 1, and the second end of the third resistor R3 is connected to the first end of the fourth resistor R4 and the signal output module AD1. The first end of the fourth resistor R4 is connected to the signal output module AD1, and the second end of the fourth resistor R4 is grounded.

[0033] It should be noted that W1 mentioned above is a reflective infrared sensor, model Everlight ITR1610. Capacitors C1 and C3 act as filters; resistor R2 controls the current at the transmitting end of W1; resistor R1 controls the voltage output at the receiving end; U1A performs follower filtering on the voltage value at the infrared receiving end; R3 and R4 are voltage divider resistors at the back end of the voltage follower, adjusting the output voltage to between 0 and 3.3V, which conforms to the acquisition range of most chip I / O ports.

[0034] When the ambient light in the hospital changes, the receiver of W1 is prone to misinterpretation. This is because, when the ambient light changes, the receiver of W1 cannot distinguish whether the change in amplitude is due to a change in the ambient light or a change in the reflection of water from the tank. To address this, an NMOS transistor is connected to pin 1 of W1, and a PWM controller is used to switch Q1, thereby controlling the on / off state of the transmitter of W1. When Q1 is off, W1 is off, and the voltage V at the receiver is... off The change mainly comes from ambient light. When Q1 is turned on, W1 is also turned on, and at this time the voltage V at the receiver... on The change primarily originates from the ambient light combined with the voltage generated by the W1 transmitter. At this time, V... on -V off This is the original voltage value at the transmitting end. Therefore, by changing the activation of W1 to PWM control, interference with ambient light is reduced. During operation, Q1 is first turned off, causing W1 to turn off, and the voltage V at the receiving end is then determined. off Then turn on Q1 to determine the voltage V at the receiving end. off Finally, V on -V off This is the voltage value used to remove interference at the transmitting end.

[0035] In actual testing, the value of the infrared liquid level detection circuit increases with the reflection of the medium (liquid), corresponding to the channel value. Preferably, two infrared sensors, W1 and W2, are used to detect the liquid level at the max and min lines of the humidifier, respectively. When the liquid level in the humidifier is empty, the microcontroller records the initial values ​​of infrared sensors W1 and W2. When the liquid level in the humidifier is below the min line, the liquid level detected by W1 and W2 remains at the initial value, and the machine alarms for low liquid level. When the liquid level in the humidifier is between the min and max lines, infrared sensor W2 detects liquid in the humidifier, while W1 detects no liquid, and the machine does not alarm. When the liquid level in the humidifier is above the max line, W1 and W2 detect liquid in the humidifier, and the value is greater than the initial value, at which point the machine alarms for high liquid level. See Table 1 for the detection status table.

[0036] Table 1 Detection Status Table

[0037]

[0038] The above embodiments are only for illustrating the technical concept and features of this utility model, and are intended to enable those skilled in the art to understand the content of this utility model and implement it accordingly. They should not be construed as limiting the scope of protection of this utility model. All equivalent changes or modifications made in accordance with the spirit and essence of this utility model should be included within the scope of protection of this utility model.

Claims

1. An infrared liquid level detection circuit, characterized in that, The infrared liquid level detection circuit includes: an infrared receiving module, a signal processing module, and a signal output module; The infrared receiving module includes a field-effect transistor and an infrared sensor. The field-effect transistor includes a first input terminal and a first output terminal. The first input terminal is connected to a signal input terminal, which is used to input an adjustment signal. The adjustment signal is used to adjust the opening or closing of the field-effect transistor. The infrared sensor includes a transmitting terminal and a receiving terminal, and the first output terminal is connected to the transmitting terminal. The signal processing module includes an operational amplifier, which includes a second input terminal and a second output terminal. The receiving terminal is connected to the second input terminal, and the second output terminal is connected to the signal output module. The signal output module is used to output the infrared detection liquid level voltage.

2. The infrared liquid level detection circuit according to claim 1, characterized in that, The field-effect transistor is an N-type metal-oxide-semiconductor transistor.

3. The infrared liquid level detection circuit according to claim 1, characterized in that, The adjustment signal is a pulse width modulation signal.

4. The infrared liquid level detection circuit according to claim 1, characterized in that, The infrared receiving module further includes a first resistor, a second resistor, and a first capacitor. The transmitting end includes a first transmitting end and a second transmitting end, and the receiving end includes a first receiving end and a second receiving end. The first end of the first capacitor is connected to the first input end and the signal input end, and the second end of the first capacitor is grounded. The first end of the first resistor is connected to a 5V power supply, and the second end of the first resistor is connected to the first receiving end and the second input end. The first end of the second resistor is connected to a 5V power supply, and the second end of the second resistor is connected to the second transmitting end. The first output end is connected to the first transmitting end, the second receiving end is grounded, and the first receiving end is connected to the second input end.

5. The infrared liquid level detection circuit according to claim 4, characterized in that, The second input terminal includes a non-inverting input terminal and an inverting input terminal; the second end of the first resistor is connected to the non-inverting input terminal, the first receiving terminal is connected to the non-inverting input terminal, and the inverting input terminal is connected to the second output terminal.

6. The infrared liquid level detection circuit according to claim 5, characterized in that, The signal processing module further includes a second capacitor, a third resistor, and a fourth resistor; the operational amplifier further includes a first interface and a second interface, the first interface being connected to a 5V power supply, the second interface being grounded, the first end of the second capacitor being connected to the 5V power supply and the first interface, the second end of the second capacitor being grounded, the first end of the third resistor being connected to the second output terminal, the second end of the third resistor being connected to the first end of the fourth resistor and the signal output module, the first end of the fourth resistor being connected to the signal output module, and the second end of the fourth resistor being grounded.

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