Infrared detection circuit, stylus circuit and stylus

Abstract

The utility model relates to the technical field of touch control pens, and discloses an infrared detection circuit, a touch control pen circuit and a touch control pen, the infrared detection circuit is applied to the touch control pen, the infrared detection circuit comprises an infrared acquisition unit and a comparison unit, an input end of the infrared acquisition unit inputs an external infrared signal, and an output end of the infrared acquisition unit compares the external infrared signal with the comparison unit. A first end of the infrared acquisition unit is connected with a power supply of the stylus, a first end of the comparison unit and a first power supply end of the comparison unit, a second end of the infrared acquisition unit is connected with a third end of the comparison unit and a second power supply end of the comparison unit and then is grounded, and an output end of the infrared acquisition unit is connected with the second end of the comparison unit; the infrared acquisition unit is used for adjusting an internal resistance value based on the infrared signal so as to adjust the magnitude of the output end voltage; and when the voltage of the output end of the infrared acquisition unit is greater than the threshold voltage of the comparison unit, the comparison unit outputs an alarm signal. The touch pen can detect infrared signals and give an alarm, and safety of privacy information of a user is guaranteed.

Description

TECHNICAL FIELD

[0001] The utility model relates to touch pen technical field, concretely relates to an infrared detection circuit, touch pen circuit and touch pen. BACKGROUND

[0002] Touch pen includes passive capacitance pen and active capacitance pen, because active capacitance pen is more sensitive than passive capacitance pen in the use process, therefore, active capacitance pen is commonly used in the market at present.Capacitance pen is one of the more common life supplies of user, and currently active capacitance pen only has functions such as writing and drawing, eraser, motor vibration.Because cameras are everywhere in the current environment, some miniature cameras can steal screen information when user uses capacitance pen to write and draw, and the security of user's private information is difficult to guarantee. SUMMARY

[0003] Therefore, the utility model provides an infrared detection circuit, touch pen circuit and touch pen to solve the problem that touch pen does not have infrared detection function.

[0004] In the first aspect, the utility model provides an infrared detection circuit, which is applied to a touch pen, and includes an infrared acquisition unit and a comparison unit, wherein the input end of the infrared acquisition unit inputs an external infrared signal, the first end of the infrared acquisition unit is connected with the power supply of the touch pen, the first end of the comparison unit and the first power supply end of the comparison unit, the output end of the infrared acquisition unit is connected with the second end of the comparison unit, the second end of the infrared acquisition unit is connected with the third end of the comparison unit and the second power supply end of the comparison unit and then grounded, and the infrared acquisition unit is used to adjust the internal resistance value based on the infrared signal, so as to adjust the size of the output end voltage; when the voltage of the output end of the infrared acquisition unit is greater than the threshold voltage of the comparison unit, the comparison unit outputs an alarm signal.

[0005] The infrared detection circuit provided by the utility model has the infrared detection and alarm functions when applied to the touch pen, the voltage input to the comparison unit by the infrared acquisition unit is increased when the infrared acquisition unit identifies the infrared signal, the comparison unit outputs an alarm signal when the comparison unit determines that the voltage of the output end of the infrared acquisition unit is greater than the threshold voltage of the comparison unit, the user is reminded that there is an infrared camera in the surrounding environment, the security of the private information of the user is improved, and the practical function of the touch pen is increased.

[0006] In an alternative embodiment, the infrared acquisition unit comprises a photodiode and a first resistor, wherein the input end of the photodiode inputs the external infrared signal, the cathode of the photodiode is connected with the first power supply end of the comparison unit, the anode of the photodiode is connected with the second end of the comparison unit and the first end of the first resistor, the photodiode is used to reduce the internal resistance based on the external infrared signal, so that the voltage of the anode of the photodiode is increased; the second end of the first resistor is connected with the second power supply end of the comparison unit and then grounded.

[0007] In an alternative embodiment, the comparison unit comprises a voltage comparator and a threshold adjusting unit, wherein the non-inverting input end of the voltage comparator is connected with the output end of the infrared acquisition unit, the inverting input end of the voltage comparator is connected with the first end of the threshold adjusting unit, the first power supply end of the voltage comparator is connected with the second end of the threshold adjusting unit and the power supply of the stylus, and the second power supply end of the voltage comparator is connected with the third end of the threshold adjusting unit and the second end of the infrared acquisition unit; the voltage of the first end of the threshold adjusting unit is adjusted by adjusting the resistance value of the threshold adjusting unit, and the voltage of the first end of the threshold adjusting unit is used as the threshold voltage; when the voltage of the output end of the infrared acquisition unit is greater than the threshold voltage, the voltage comparator outputs an alarm signal.

[0008] The infrared detection circuit provided by the utility model can be applied to various application scenarios by adjusting the resistance value of the threshold adjusting unit to adjust the size of the threshold voltage, so that the application range of the infrared detection circuit is improved.

[0009] In an alternative embodiment, the threshold adjusting unit comprises an adjustable resistor, wherein the first end of the adjustable resistor is connected with the inverting input end of the voltage comparator, the second end of the adjustable resistor is connected with the first power supply end of the voltage comparator, and the third end of the adjustable resistor is connected with the second power supply end of the voltage comparator.

[0010] In an alternative embodiment, the infrared detection circuit further comprises an alarm unit, wherein the first end of the alarm unit is connected with the output end of the comparison unit, and the second end of the alarm unit is connected with the second power supply end of the comparison unit; the alarm unit is used to alarm based on the alarm signal.

[0011] In an alternative embodiment, the alarm unit comprises a feedback unit and a current limiting unit, wherein the first end of the feedback unit is connected with the output end of the comparison unit, the second end of the feedback unit is connected with the first end of the current limiting unit, and the feedback unit is used to visually alarm based on the alarm signal; the second end of the current limiting unit is connected with the second power supply end of the comparison unit, and the current limiting unit is used to limit the current size of the feedback unit.

[0012] In an alternative embodiment, the infrared detection circuit further comprises a contact switch, wherein a first end of the contact switch is connected to the power supply of the stylus, and a second end of the contact switch is connected to the first end of the infrared acquisition unit; when the contact switch is closed, the infrared acquisition unit and the comparison unit are powered on and start working.

[0013] The infrared detection circuit provided by the utility model can control the contact switch to be closed when infrared detection is needed, and can control the contact switch to be opened when infrared detection is not needed, thereby reducing the power consumption of the infrared detection circuit.

[0014] In a second aspect, the utility model provides a stylus circuit, which comprises a battery, a control module, a signal transceiver module, a sensor module, a communication module and the infrared detection circuit of the first aspect or any of the corresponding embodiments, wherein the power supply end of the control module is connected to the battery and the first end of the infrared acquisition unit, the first end of the control module is connected to the signal transceiver module, the second end of the control module is connected to the sensor module, and the third end of the control module is connected to the communication module.

[0015] The stylus circuit provided by the utility model can improve the user's privacy information security and increase the practical function of the stylus.

[0016] In an alternative embodiment, the sensor module comprises one or more of a temperature sensor, an ambient light sensor, a contact sensor, a pressure sensor and a magnetic sensor.

[0017] In a third aspect, the utility model provides a stylus, which comprises a stylus body, a red light filter, a pen cap and the stylus circuit of the second aspect or any of the corresponding embodiments, wherein the stylus circuit is arranged in the stylus body; the pen cap is detachably mounted on the tail of the stylus body; the red light filter is arranged in the clamping groove between the pen cap and the tail of the stylus body, and the infrared acquisition unit is arranged close to the red light filter, so that the external infrared signal is input to the input end of the infrared acquisition unit through the pen cap and the red light filter in sequence.

[0018] The stylus provided by the utility model can filter out the infrared light in the ambient light through the red light filter, so that the infrared light can be input to the infrared acquisition unit without obstruction through the transparent or translucent pen cap; when the infrared acquisition unit identifies the infrared signal, the voltage input to the comparison unit by the infrared acquisition unit is increased; when the comparison unit determines that the voltage at the output end of the infrared acquisition unit is greater than the threshold voltage of the comparison unit, the comparison unit outputs an alarm signal to remind the user that there is an infrared camera in the surrounding environment, thereby improving the user's privacy information security and increasing the practical function of the stylus. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a component diagram of an infrared detection circuit according to an embodiment of the present utility model;

[0021] Figure 2 This is a specific circuit structure diagram of the infrared detection circuit according to an embodiment of the present utility model;

[0022] Figure 3 This is another specific circuit structure diagram of the infrared detection circuit according to an embodiment of the present utility model;

[0023] Figure 4 This is a schematic diagram of a stylus circuit according to an embodiment of the present invention;

[0024] Figure 5 This is a component diagram of a stylus according to an embodiment of the present utility model;

[0025] Explanation of reference numerals in the attached figures:

[0026] 1: Infrared detection circuit; 2: Battery; 3: Control module; 4: Signal transceiver module; 5: Sensor module; 6: Communication module;

[0027] 11: Infrared acquisition unit; 12: Comparison unit; 13: Alarm unit; 14: Contact switch;

[0028] 121: Voltage comparator; 122: Threshold adjustment unit;

[0029] 131: Feedback unit; 132: Current limiting unit. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0031] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0032] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can also refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0033] Furthermore, the technical features involved in the different embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0034] This embodiment provides an infrared detection circuit 1, which is applied to a stylus, such as... Figure 1 As shown, the infrared detection circuit 1 includes an infrared acquisition unit 11 and a comparison unit 12. The input terminal of the infrared acquisition unit 11 receives an external infrared signal. The first terminal of the infrared acquisition unit 11 is connected to the power supply of the stylus, the first terminal of the comparison unit 12, and the first power supply terminal of the comparison unit 12. The output terminal of the infrared acquisition unit 11 is connected to the second terminal of the comparison unit 12. The second terminal of the infrared acquisition unit 11 is connected to the third terminal of the comparison unit 12 and the second power supply terminal of the comparison unit 12, and then grounded.

[0035] Specifically, Figure 1 When the stylus is powered on, the infrared acquisition unit 11 and the comparison unit 12 begin to operate. When an external infrared signal is present, the resistance inside the infrared acquisition unit 11 changes, altering the voltage division of the stylus power supply voltage and thus changing the output voltage of the infrared acquisition unit 11. For example, when an external infrared signal is present, if the output voltage of the infrared acquisition unit 11 increases to exceed the internal threshold voltage of the comparison unit 12, the comparison unit 12 outputs an alarm signal, causing the stylus to provide sound, light, or vibration feedback to alert the user that there is infrared light in the surrounding environment.

[0036] Optionally, the infrared acquisition unit 11 may include infrared sensing elements such as photodiodes, whose internal resistance can change with the intensity of the infrared signal.

[0037] The infrared detection circuit provided in this embodiment is applied to the stylus to enable the stylus to have infrared detection and alarm functions. When the infrared acquisition unit recognizes an infrared signal, the voltage input from the infrared acquisition unit to the comparison unit increases. When the comparison unit determines that the voltage at the output terminal of the infrared acquisition unit is greater than the threshold voltage of the comparison unit, the comparison unit outputs an alarm signal to remind the user that there is an infrared camera in the surrounding environment, thereby improving the user's privacy information security and increasing the practical functions of the stylus.

[0038] In some alternative implementations, such as Figure 2 As shown, the infrared acquisition unit 11 includes a photodiode D0 and a first resistor R1. The input terminal of the photodiode D0 receives an external infrared signal. The cathode of the photodiode D0 is connected to the first power supply terminal of the comparator unit 12. The anode of the photodiode D0 is connected to the second terminal of the comparator unit 12 and the first terminal of the first resistor R1. The second terminal of the first resistor R1 is connected to the second power supply terminal of the comparator unit 12 and then grounded.

[0039] Specifically, Figure 2 In the process, photodiode D0 reduces its internal resistance based on the externally incident infrared signal. Since the voltage difference between the cathode of photodiode D0 and the second end of the first resistor R1 is equal to the constant power supply voltage of the stylus, when the resistance of photodiode D0 decreases, the voltage drop across the first resistor R1 increases. Furthermore, the greater the intensity of the external infrared signal, the greater the voltage drop across the first resistor R1. Therefore, the voltage at the intersection of the anode of photodiode D0 and the first end of the first resistor R1 increases with the intensity of the external infrared signal. When the voltage at the intersection increases to exceed the internal threshold voltage of the comparison unit 12, the comparison unit 12 outputs an alarm signal.

[0040] In some alternative implementations, such as Figure 2 As shown, the comparison unit 12 includes a voltage comparator 121 and a threshold adjustment unit 122. The non-inverting input of the voltage comparator 121 is connected to the output of the infrared acquisition unit 11, the inverting input of the voltage comparator 121 is connected to the first terminal of the threshold adjustment unit 122, the first power supply terminal of the voltage comparator 121 is connected to the second terminal of the threshold adjustment unit 122 and the power supply of the stylus, and the second power supply terminal of the voltage comparator 121 is connected to the third terminal of the threshold adjustment unit 122 and the second terminal of the infrared acquisition unit 11. The voltage at the first terminal of the threshold adjustment unit 122 is adjusted by adjusting the resistance value of the threshold adjustment unit 122, and the voltage at the first terminal of the threshold adjustment unit 122 is used as the threshold voltage. When the voltage at the output of the infrared acquisition unit 11 is greater than the threshold voltage, the voltage comparator 121 outputs an alarm signal.

[0041] Optionally, Figure 2 In the process, the threshold adjustment unit 122 includes an adjustable resistor R2. When producing the infrared detection circuit 1, the operator can flexibly adjust the resistance value of the adjustable resistor R2 to set the threshold voltage, thereby improving the applicability of the infrared detection circuit 1.

[0042] In some alternative implementations, such as Figure 3 As shown, the infrared detection circuit 1 further includes an alarm unit 13, wherein a first terminal of the alarm unit 13 is connected to the output terminal of the comparison unit 12, and a second terminal of the alarm unit 13 is connected to the second power supply terminal of the comparison unit 12; the alarm unit 13 is used to issue an alarm based on an alarm signal. The alarm unit can be a tactile alarm unit, a visual alarm unit, an auditory alarm unit, or other types of alarm units. For example, a tactile alarm unit may include a vibration motor; a visual alarm unit may include an LED light; and an auditory alarm unit may include a speaker, a buzzer, etc.

[0043] Specifically, for example, when alarm unit 13 is a visual alarm unit, such as Figure 3 As shown, the alarm unit 13 may include a feedback unit 131 and a current limiting unit 132. The first end of the feedback unit 131 is connected to the output end of the comparison unit 12, and the second end of the feedback unit 131 is connected to the first end of the current limiting unit 132. The feedback unit 131 is used to perform visual alarm based on the alarm signal, such as light alarm. The second end of the current limiting unit 132 is connected to the second power supply end of the comparison unit 12. The current limiting unit 132 is used to limit the current of the feedback unit 131.

[0044] In some alternative implementations, such as Figure 3 As shown, the infrared detection circuit 1 also includes a contact switch 14, wherein the first end of the contact switch 14 is connected to the power supply of the stylus, and the second end of the contact switch 14 is connected to the first end of the infrared acquisition unit 11; when the contact switch 14 is closed, the infrared acquisition unit 11 and the comparison unit 12 are powered on and start working.

[0045] Specifically, Figure 3 When a user needs to protect their privacy while using the stylus, they can press the contact switch 14 to connect the stylus power supply to the infrared detection circuit 1, thus enabling the stylus to activate the infrared detection alarm function; when privacy protection is not required, the contact switch 14 can be disconnected to save stylus power consumption.

[0046] This embodiment provides a stylus circuit, such as Figure 4As shown, it includes: battery 2, control module 3, signal transceiver module 4, sensor module 5, communication module 6, and infrared detection circuit 1 of the above embodiment or any corresponding embodiment. The power supply terminal of control module 3 is connected to the first terminal of battery 2 and infrared acquisition unit 11, the first terminal of control module 3 is connected to signal transceiver module 4, the second terminal of control module 3 is connected to sensor module 5, and the third terminal of control module 3 is connected to communication module 6.

[0047] Specifically, Figure 4 In this system, the signal transceiver module 4 transmits and receives control signals between the control module 3 and the touch screen of the electronic device, thereby determining information such as the position of the stylus on the touch screen; the communication module is used to exchange information such as battery level, charging status, and the current working status of the stylus with the electronic device.

[0048] Optionally, the sensor module 5 includes one or more of the following: a temperature sensor, an ambient light sensor, a contact sensor, a pressure sensor, and a magnetic sensor, thereby adding functions such as temperature detection, pressure detection, ambient light detection, and charging adsorption detection to the stylus circuit.

[0049] Optionally, when the power supply voltage levels of the control module 3 and the infrared detection circuit 1 are different, a voltage conversion circuit can be connected in series between the battery 2 and the infrared detection circuit 1 to convert the voltage of the battery 2 to the rated power supply voltage of the infrared detection circuit 1.

[0050] It should be noted that the functions and working principles of the control module, signal transceiver module, sensor module and communication module in this embodiment are all implemented using relatively mature technologies disclosed in the prior art. That is, this application only protects the structure of the stylus circuit, and the specific working principle of each module will not be described in detail here.

[0051] The stylus circuit provided in this embodiment increases the voltage input to the comparison unit when the infrared acquisition unit detects an infrared signal. When the comparison unit determines that the voltage at the output terminal of the infrared acquisition unit is greater than the threshold voltage of the comparison unit, the comparison unit outputs an alarm signal to remind the user that there is an infrared camera in the surrounding environment, thereby improving the user's privacy information security and increasing the practical functions of the stylus.

[0052] This embodiment provides a stylus, such as Figure 5As shown, it includes: a stylus body, a red light filter, a pen cap, and a stylus circuit according to the second aspect or any corresponding embodiment described above. The stylus circuit is disposed within the stylus body; the pen cap is detachably mounted at the tail of the stylus body; the red light filter is disposed in a slot between the pen cap and the tail of the stylus body; and the infrared acquisition unit 11 is disposed close to the red light filter, so that external infrared signals are sequentially input to the input terminal of the infrared acquisition unit 11 through the pen cap and the red light filter.

[0053] Optionally, Figure 5 In this process, the pen cap can be fully transparent, semi-transparent, or transparent at the top, allowing external infrared signals to penetrate the pen cap and enter the infrared acquisition unit 11.

[0054] Specifically, Figure 5 The stylus body is hollow, with a detachable cap mounted at the tail. A red light filter is sandwiched between the cap and the tail. The feedback unit uses an LED. External infrared signals are transmitted through the cap to the input of the infrared acquisition unit 11. The red light filter filters out interference light sources other than red light. The user can control the circuit between the battery 2 and the infrared acquisition unit 11 by pressing the contact switch 14, thus enabling or disabling the stylus's infrared detection function. When infrared light is detected in the surrounding environment, the comparison unit 12 outputs an alarm signal to control the LED to illuminate and alert the user. An electrode is located in the pen tip. This electrode is used to determine the stylus's position on the touchscreen by transmitting and / or receiving signals via the signal transceiver module 4 during contact between the stylus and the touchscreen.

[0055] It should be noted that the working principle of the stylus in this embodiment is consistent with that of the above embodiments and any optional implementations, and will not be repeated here. Furthermore, some modules and components in the above embodiments are not included in... Figure 5 As shown in the above embodiments, in actual production, those skilled in the art can set the spatial position of each component and adjust the connection relationship according to the content described in the above embodiments, and there are no restrictions here.

[0056] The stylus provided in this embodiment has a red light filter that can filter out infrared light from ambient light, allowing infrared light to be input to the infrared acquisition unit without obstruction through the transparent or semi-transparent pen cap. When the infrared acquisition unit detects an infrared signal, the voltage input to the comparison unit increases. When the comparison unit determines that the voltage at the output terminal of the infrared acquisition unit is greater than the threshold voltage of the comparison unit, the comparison unit outputs an alarm signal to remind the user that there is an infrared camera in the surrounding environment, thereby improving the user's privacy information security and increasing the practical functions of the stylus.

[0057] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. An infrared detection circuit, characterized by, The infrared detection circuit applied to a stylus comprises an infrared acquisition unit and a comparison unit, An input end of the infrared acquisition unit inputs an external infrared signal, a first end of the infrared acquisition unit is connected with a power supply of the stylus, a first end of the comparison unit and a first power supply end of the comparison unit, an output end of the infrared acquisition unit is connected with a second end of the comparison unit, a second end of the infrared acquisition unit is connected with a third end of the comparison unit and a second power supply end of the comparison unit and then grounded, and the infrared acquisition unit is used for adjusting an internal resistance value based on the infrared signal, so as to adjust a size of a voltage of the output end. When the voltage of the output end of the infrared acquisition unit is greater than a threshold voltage of the comparison unit, the comparison unit outputs an alarm signal.

2. The infrared detection circuit of claim 1, wherein, The infrared acquisition unit comprises a photodiode and a first resistor, An input end of the photodiode inputs an external infrared signal, a cathode of the photodiode is connected with the first power supply end of the comparison unit, an anode of the photodiode is connected with the second end of the comparison unit and a first end of the first resistor, and the photodiode is used for reducing an internal resistance based on the external infrared signal, so that the voltage of the anode of the photodiode is increased. A second end of the first resistor is connected with the second power supply end of the comparison unit and then grounded.

3. The infrared detection circuit of claim 1, wherein, The comparison unit comprises a voltage comparator and a threshold adjusting unit, A non-inverting input end of the voltage comparator is connected with the output end of the infrared acquisition unit, an inverting input end of the voltage comparator is connected with a first end of the threshold adjusting unit, a first power supply end of the voltage comparator is connected with a second end of the threshold adjusting unit and the power supply of the stylus, and a second power supply end of the voltage comparator is connected with a third end of the threshold adjusting unit and a second end of the infrared acquisition unit; The voltage of the first end of the threshold adjusting unit is adjusted by adjusting a resistance value of the threshold adjusting unit, and the voltage of the first end of the threshold adjusting unit serves as the threshold voltage; When the voltage of the output end of the infrared acquisition unit is greater than the threshold voltage, the voltage comparator outputs an alarm signal.

4. The infrared detection circuit of claim 3, wherein, The threshold adjusting unit comprises an adjustable resistor, A first end of the adjustable resistor is connected with the inverting input end of the voltage comparator, a second end of the adjustable resistor is connected with the first power supply end of the voltage comparator, and a third end of the adjustable resistor is connected with the second power supply end of the voltage comparator.

5. The infrared detection circuit of claim 1, wherein, Further comprising: An alarm unit, wherein A first end of the alarm unit is connected with the output end of the comparison unit, and a second end of the alarm unit is connected with the second power supply end of the comparison unit; The alarm unit is used for alarming based on the alarm signal.

6. The infrared detection circuit of claim 5, wherein, The alarm unit comprises a feedback unit and a current limiting unit, wherein A first end of the feedback unit is connected with the output end of the comparison unit, a second end of the feedback unit is connected with a first end of the current limiting unit, and the feedback unit is used for visually alarming based on the alarm signal; The second end of the current limiting unit is connected with the second power supply end of the comparison unit, and the current limiting unit is used for limiting the current size of the feedback unit.

7. The infrared detection circuit of claim 1, wherein, Further comprising: The contact switch, wherein, The first end of the contact switch is connected with the power supply of the stylus, and the second end of the contact switch is connected with the first end of the infrared acquisition unit; When the contact switch is closed, the infrared acquisition unit and the comparison unit are powered on and start to work.

8. A stylus circuit, comprising: Comprising: The battery, the control module, the signal transceiver module, the sensor module, the communication module, and the infrared detection circuit according to any one of claims 1 to 7, wherein, The power supply end of the control module is connected with the battery and the first end of the infrared acquisition unit, the first end of the control module is connected with the signal transceiver module, the second end of the control module is connected with the sensor module, and the third end of the control module is connected with the communication module. 9.The stylus circuit according to claim 8, wherein The sensor module comprises one or more of a temperature sensor, an ambient light sensor, a contact sensor, a pressure sensor, and a magnetic sensor.

10. A stylus, characterized by Comprising: The stylus body, the red light filter, the pen cap, and the stylus circuit according to any one of claims 8 to 9, wherein The stylus circuit is arranged in the stylus body; The pen cap is detachably mounted at the tail of the stylus body; The red light filter is arranged in the clamping groove between the pen cap and the tail of the stylus body, and the infrared acquisition unit is arranged close to the red light filter, so that the external infrared signal is input to the input end of the infrared acquisition unit through the pen cap and the red light filter in sequence.

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