A myopia-preventing distance measuring system and device

Abstract

The utility model relates to a kind of myopia-preventing distance measurement system and equipment, the system includes MCU and infrared detection module, and the infrared detection module is composed of infrared emitting diode, photosensitive triode and operational amplifier.MCU controls infrared emitting diode to emit invisible infrared light by the PWM wave of specific frequency output, and after being reflected by target object, it is received by photosensitive triode and converted into electric signal, and direct current interference caused by ambient light is filtered by setting isolation element, only keep alternating current signal for operational amplifier amplification processing, to improve ranging accuracy and stability.System judges the distance between user and screen according to the voltage signal detected, and issues a reminder through voice module when the distance is too close.The utility model system structure is simple, and the anti-interference ability is strong, and myopia problem caused by near vision can be effectively prevented.

Description

Technical Field

[0001] This utility model relates to the field of myopia prevention technology, specifically to a distance measurement system and device for myopia prevention. Background Technology

[0002] With the widespread use of smartphones and tablets, children are increasingly using these devices at close range for extended periods, which seriously impacts their vision health. Current distance detection products rely on infrared light sensing technology. The core principle of this technology is to use an infrared LED light source and capture the reflected infrared light to calculate distance. However, this mechanism performs poorly in environments with significant lighting variations. For example, in strong outdoor light, the infrared light may be severely interfered with, leading to decreased accuracy. In low-light or dark environments, insufficient strength of the infrared LED light source can also affect recognition, resulting in inaccurate distance readings and a higher risk of false alarms.

[0003] Existing myopia prevention products mostly use infrared remote controls for detection, but these are easily interfered with by other infrared signal sources, affecting normal use. If a high-precision infrared ranging module is used, the cost is relatively high, which cannot meet the requirements of electronic devices for low power consumption and low cost. Therefore, there is a need for a low-cost and effective device for detecting eye distance. Utility Model Content

[0004] To address the aforementioned problems, this utility model provides a distance measurement system for myopia prevention, comprising an MCU and an infrared detection module. The infrared detection module includes an infrared emitting diode, a phototransistor, and an operational amplifier. The MCU outputs a PWM wave to control the infrared emitting diode to emit infrared light at a preset frequency. The infrared light is reflected by the target object and received by the phototransistor. The phototransistor converts the infrared light into an electrical signal, which is then amplified and output by the operational amplifier via an isolation element. The MCU determines the distance to the target object by detecting the electrical signal output by the amplifier.

[0005] Preferably, the PWM wave is connected to the base of the transistor via a first resistor, the collector of the transistor is connected to the cathode of the infrared emitting diode, and the emitter of the transistor is grounded, which is used to drive the infrared emitting diode to emit infrared light at a preset frequency.

[0006] Preferably, the isolation element is a capacitor connected between the output terminal of the phototransistor and the positive input of the operational amplifier, used to isolate the DC component input to the operational amplifier.

[0007] Based on the above scheme, the infrared detection module also includes a second resistor. The emitter of the phototransistor is connected to the first end of the second resistor, the second end of the second resistor is grounded, and the emitter of the phototransistor is connected to the positive input of the operational amplifier via the capacitor.

[0008] Based on the above scheme, a voice module is also included. The voice module is connected to the MCU. When the distance to the detected target object is less than a set threshold, the MCU outputs a pulse signal to the voice module, and the voice module issues a voice prompt.

[0009] On the other hand, based on the aforementioned anti-myopia distance measurement system, this application also provides an anti-myopia distance measurement device, which further includes a charging interface, a charging circuit, a battery, and a voltage regulator module. The charging interface is used to connect to a power source, and the power source charges the battery through the charging circuit after passing through the charging interface. The battery supplies power to the anti-myopia distance measurement device, and the voltage regulator module is used to stabilize the output voltage of the battery.

[0010] Based on the above scheme, the battery outputs a voltage of 3.3V, the anode of the infrared emitting diode is connected to a voltage of 3.3V via a third resistor, and the collector of the phototransistor is connected to a voltage of 3.3V.

[0011] Furthermore, the device also includes an LED indicator module for indicating charging status and detection status.

[0012] Compared with the prior art, the beneficial effects of this utility model are as follows: 1. By outputting a PWM waveform of a specific frequency from the MCU, the infrared emitting diode is driven to emit infrared light with a wavelength of 940nm at a fixed frequency. This modulation method ensures that the system only recognizes a phototransistor receiving reflected light of the same frequency as a valid signal. This effectively avoids interference from other unmodulated infrared light in the environment (such as fluorescent lights, TV remote controls, etc.) on the detection results, thereby improving the system's anti-interference capability and ranging accuracy. 2. This invention incorporates a capacitor as an isolation element between the phototransistor and the operational amplifier, effectively filtering out the DC component caused by ambient light and allowing only the AC signal generated by PWM modulation to pass through. Even in strong or weak light environments, it prevents misjudgments due to changes in background light intensity, thus significantly improving the stability of the detection signal and the ranging accuracy, ensuring reliable operation of the system under various lighting conditions. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the infrared detection module circuit of this utility model; Figure 2 This is a schematic diagram of the MCU circuit of this utility model; Figure 3 This is a graph showing the relationship between the detection sensitivity of a phototransistor to different wavelengths of light. Figure 4 This is the circuit diagram of the voice module of this utility model; Figure 5 This is the circuit diagram of the charging interface of this utility model; Figure 6 This is the charging circuit diagram of this utility model; Figure 7 This is the voltage regulator circuit diagram of this utility model; Figure 8 This is the circuit diagram for the LED indicator light of this utility model. Detailed Implementation

[0014] The present invention will be further described below with reference to the accompanying drawings: In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0015] The specific embodiments of this utility model are as follows.

[0016] First, this utility model discloses a distance measurement system for preventing myopia, such as Figure 1 and Figure 2 As shown, it includes a microcontroller (MCU) and an infrared detection module. The infrared detection module includes an infrared emitting diode (D1) and a phototransistor (Q2). D1 is used to emit invisible infrared light, and Q2 is used to receive invisible infrared light.

[0017] Preferably, D1 emits 940nm invisible infrared light. This 940nm infrared light will not cause visual interference to the user and can reduce interference from ambient light, improving detection accuracy. In addition, such as... Figure 3 As shown, Q2 has high sensitivity to 940nm infrared light and can efficiently detect infrared signals.

[0018] To prevent interference from other infrared light sources in the environment, the MCU's IR_PWM pin outputs a PWM waveform of a certain frequency to control D1 to emit infrared light at the same frequency. Preferably, transistor Q3 is used to control D1. The MCU controls the on / off state of Q3 by outputting a PWM waveform of a certain frequency, thereby causing D1 to emit infrared light at the same frequency. Specifically, after the PWM wave is output from the IR_PWM pin, it passes through the first resistor R19 and is connected to the base of Q3. The collector of Q3 is connected to the cathode of D1, and the emitter of Q3 is grounded.

[0019] The working principle is as follows: When the PWM signal is high, transistor Q3 is turned on, allowing current to flow from the power supply through D1 to ground; when the PWM signal is low, transistor Q3 is turned off, cutting off the current path and causing D1 to stop emitting infrared light. Since transistor Q3 periodically turns on and off according to the PWM signal, the infrared emitting diode D1 will emit infrared light at the same frequency.

[0020] In other embodiments, field-effect transistors, driver chips, etc., can also be used to control the infrared emitting diode.

[0021] Furthermore, the MCU outputs a PWM wave to control D1 to emit infrared light at a preset frequency. The infrared light is reflected by the target object and received by the phototransistor Q2. Q2 converts the infrared light into an electrical signal. In one embodiment, the 940nm infrared light emitted by D1 is reflected back by the face and received by Q2. The stronger the received 940nm infrared light, the greater the current passing through Q2, indicating that the face is closer to the electronic device.

[0022] The infrared detection module also includes a second resistor R21. The emitter of Q3 is connected to the first end of the second resistor R21, and the second end of R21 is grounded. The current flowing through Q2 passes through R21 and, through U=IR, yields the voltage value ADC_Y. It should be noted that because the infrared light emitted by D1 is a PWM output, the current received by Q2 and ADC_Y are also PWM waveforms.

[0023] The ADC_Y is connected to an isolation element to isolate the DC component. The AC component is then input to the operational amplifier U3 after passing through the isolation element. The AC component is amplified by U3 and output to the MCU's IO pin for ADC voltage detection. The higher the voltage detection or the longer the high voltage output time, the closer the face is to the infrared transmitter and receiver.

[0024] To mitigate interference from ambient light intensity, an isolation element is used to isolate the DC component. Under strong ambient light, the current of Q2 is higher, while under weak ambient light, the current of Q2 is lower. The DC component of Q2 is not amplified by U3, thus avoiding the influence of ambient light variations on detection distance changes. Preferably, capacitor C14 is used to isolate the DC component, and the emitter of Q3 is connected to the positive input of the operational amplifier via C14.

[0025] The working principle is as follows: Adding capacitor C14 to the circuit and connecting it between the output of Q2 and the positive input of operational amplifier U3 effectively blocks the DC component, allowing only the AC component to pass through. When the ambient light intensity changes, the generated DC component is blocked by capacitor C14 and does not enter operational amplifier U3; the reflected 940nm infrared light signal is a PWM-modulated AC signal that can pass smoothly through capacitor C14 and be amplified by U3.

[0026] In other embodiments, high-pass filters, digital filters, etc. can also be used to filter the DC component. The capacitor used in this application is a simple and inexpensive isolation element, which is effective for distance detection systems that need to remove ambient light interference.

[0027] The voltage value is amplified by U3 and output as an electrical signal ADC2. ADC2 is connected to the MCU's I / O port. The MCU uses its internal ADC module to perform voltage detection on the acquired ADC2 electrical signal. The obtained voltage detection value reflects the distance between the target object (such as a face) and the infrared receiving element. The higher the voltage detection value or the longer the high voltage lasts, the closer the target object is to the infrared emitting and receiving unit. This is because the intensity of the reflected infrared light is greater, meaning the target object is closer.

[0028] It's important to note that in pulse signals, the "high-voltage period" refers to the time within each pulse cycle when the voltage is above a certain threshold. If the target object is close, the intensity of the reflected infrared light is higher, resulting in a longer high-voltage period within each pulse cycle. Conversely, if the target object is far away, the intensity of the reflected infrared light is lower, resulting in a shorter high-voltage period within each pulse cycle.

[0029] Furthermore, the system also includes a voice module capable of providing prompts to the user, such as... Figure 4 As shown, the voice module is connected to the MCU. When the distance to the target object is less than the set threshold (healthy eye distance), the MCU outputs a pulse signal to the voice module, and the voice module issues a voice prompt, such as: "The distance is too close, please move away."

[0030] On the other hand, based on the aforementioned distance measurement system for myopia prevention, this application discloses a distance measurement device for myopia prevention, such as... Figures 5 to 7 As shown, the device also includes a charging interface, a charging circuit, a battery, and a voltage regulator module. The charging interface is a Type-C charging interface used to connect to a 5V power supply. The 5V power supply is connected to the charging circuit via the charging interface. The charging circuit includes a charging chip U4, which charges the battery (BAT). The battery (BAT) powers the distance measurement device for myopia prevention. To provide a stable 3.3V voltage to the modules and circuits within the device, a voltage regulator module is used to stabilize the battery's output voltage VCC_3V3. The battery outputs a 3.3V voltage. The anode of D1 is connected to the 3.3V voltage via a third resistor R16, and the collector of Q3 is also connected to the 3.3V voltage, thus powering D1 and Q3.

[0031] like Figure 8 As shown, the device also includes an LED indicator module for indicating the charging status and distance detection status of the device. When the device is connected to an external power source via the Type-C charging interface and begins charging, the MCU detects this status and controls the LED indicator module via a control signal, with LED1 indicating that charging is in progress. When the battery is fully charged, the MCU switches the signal to control LED1, indicating that charging is complete. At the same time, the status of LED2 indicates that the device is in distance detection mode.

[0032] The overall working principle of this application is as follows: Infrared emitting diode D1 emits invisible infrared light with a wavelength of 940nm at a specific frequency. The MCU controls transistor Q3 to drive D1 via a PWM waveform, thereby avoiding interference from other infrared light sources in the environment. Phototransistor Q2 receives the reflected infrared light and converts it into a current signal. The current signal is converted into a voltage signal through resistor R21, and after the DC component is isolated by capacitor C14, it enters operational amplifier U3 for amplification. The amplified voltage signal is sent to the MCU's ADC module for sampling and analysis, and the distance to the target object is determined based on the change in voltage value. The MCU determines whether the distance between the user's face and the electronic device is less than a preset threshold based on the collected voltage signal. If the distance is too close, the system can issue visual and auditory warnings through LED lights and a voice reminder module to prompt the user to adjust the viewing distance. The device is powered by a battery and maintains a stable 3.3V voltage output through a charging interface, charging circuit, and voltage regulator module.

[0033] The foregoing has shown and described the basic principles and main features of this utility model. It is obvious to those skilled in the art that this utility model is not limited to the details of the above exemplary embodiments. Therefore, the embodiments should be regarded as exemplary and non-limiting. The scope of this utility model is defined by the appended claims rather than the foregoing description. Therefore, it is intended to include all changes that fall within the meaning and scope of the equivalents of the claims within this utility model.

[0034] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A distance measurement system for myopia prevention, characterized in that, The system includes an MCU and an infrared detection module. The infrared detection module includes an infrared emitting diode, a phototransistor, and an operational amplifier. The MCU outputs a PWM wave to control the infrared emitting diode to emit infrared light at a preset frequency. The infrared light is reflected by the target object and received by the phototransistor. The phototransistor converts the infrared light into an electrical signal. The electrical signal is input to the operational amplifier through an isolation element for amplification and output. The MCU determines the distance to the target object by detecting the electrical signal output by the amplifier.

2. The distance measurement system for myopia prevention according to claim 1, characterized in that, The PWM wave is connected to the base of the transistor via a first resistor. The collector of the transistor is connected to the cathode of the infrared emitting diode. The emitter of the transistor is grounded, which is used to drive the infrared emitting diode to emit infrared light at a preset frequency.

3. The distance measurement system for myopia prevention according to claim 2, characterized in that, The isolation element is a capacitor connected between the output terminal of the phototransistor and the positive input of the operational amplifier, used to isolate the DC component input to the operational amplifier.

4. The distance measurement system for myopia prevention according to claim 3, characterized in that, The infrared detection module also includes a second resistor. The emitter of the phototransistor is connected to the first end of the second resistor, the second end of the second resistor is grounded, and the emitter of the phototransistor is connected to the positive input of the operational amplifier via the capacitor.

5. The distance measurement system for myopia prevention according to claim 1, characterized in that, It also includes a voice module, which is connected to the MCU. When the distance to the detected target object is less than a set threshold, the MCU outputs a pulse signal to the voice module, and the voice module issues a voice prompt.

6. A distance measurement device for preventing myopia, characterized in that, The device includes the anti-myopia distance measurement system according to any one of claims 1-5, and further includes a charging interface, a charging circuit, a battery and a voltage regulator module. The charging interface is used to connect to a power source. The power source charges the battery through the charging circuit after passing through the charging interface. The battery supplies power to the anti-myopia distance measurement device. The voltage regulator module is used to stabilize the output voltage of the battery.

7. A distance measuring device for preventing myopia according to claim 6, characterized in that, The battery outputs a voltage of 3.3V, the anode of the infrared emitting diode is connected to a voltage of 3.3V via a third resistor, and the collector of the phototransistor is connected to a voltage of 3.3V.

8. A distance measuring device for preventing myopia according to claim 7, characterized in that, The device also includes an LED indicator module for indicating charging and detection status.

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