An infrared trigger circuit

Abstract

The utility model relates to the field of trigger circuit especially infrared trigger circuit, include: power input, trigger signal generation unit, the noninverting input of operational amplifier is accessed a reference voltage, the base of triode is coupled with the output of operational amplifier through a resistance, the emitter of triode is grounded, infrared emission diode and current -limiting resistance are connected in series after the power input, and the other end of infrared emission diode is coupled with the collector of triode, trigger signal generation unit generates a trigger signal, the trigger signal makes the noninverting input voltage of operational amplifier higher than the reference voltage, and the operational amplifier output high level drives to make infrared emission diode work.

Description

Technical Field

[0001] This utility model relates to the field of infrared triggering circuits, and more particularly to an infrared triggering circuit. Background Technology

[0002] Infrared trigger circuits, as a fundamental photoelectric control circuit, are widely used in many electronic devices such as remote controls, security sensors, automatic door controls, and infrared temperature measurement. Their core function is to control the infrared emitter to generate a specific infrared light signal in response to external triggering conditions.

[0003] Existing infrared triggering circuit implementations mainly fall into two technical categories. One category employs dedicated infrared encoding integrated circuits or microcontroller units. While these solutions offer rich functionality and high integration, they suffer from relatively high hardware costs, complex circuit design, and the need for supporting software development. For applications with limited functionality and high cost sensitivity, their cost-effectiveness is not high, and they also increase the difficulty of production and maintenance.

[0004] Another type is the simplified circuit built with discrete components to reduce costs. However, these simplified circuits usually have significant drawbacks. For example, some solutions use mechanical switches or sensors to directly drive infrared emitters. This architecture lacks effective signal conditioning and isolation mechanisms, making the circuit's operation highly susceptible to power fluctuations, load changes, and environmental electromagnetic interference. It has poor anti-interference capabilities, is prone to false triggering or failure to trigger, and its stability and reliability are difficult to guarantee. Furthermore, the trigger threshold of such circuits is inaccurate, and their response characteristics are poor, making them unsuitable for applications requiring high control precision and response speed. Utility Model Content

[0005] To address the aforementioned issues, this invention provides an infrared triggering circuit that maintains the advantages of low hardware cost and simple structure while also possessing high stability, high anti-interference capability, and the ability to achieve fast and reliable triggering.

[0006] To achieve the above objectives, the technical solution adopted by this utility model is as follows: an infrared trigger circuit, comprising: a power input terminal; a trigger signal generation unit for generating a trigger signal in response to an external trigger operation; a voltage comparison unit, comprising an operational amplifier, the non-inverting input terminal of which is coupled to the trigger signal generation unit to receive the trigger signal, and the inverting input terminal of which is connected to a reference voltage; a driving unit, comprising a transistor, the base of which is coupled to the output terminal of the operational amplifier through a resistor, and the emitter of which is grounded; and an infrared emitting unit, comprising an infrared emitting diode and a current-limiting resistor, the infrared emitting diode being connected in series with the current-limiting resistor and then connected to the power input terminal, and the other end of the infrared emitting diode being coupled to the collector of the transistor; wherein, when the push-button switch is closed, the trigger signal causes the voltage at the non-inverting input terminal of the operational amplifier to be higher than the reference voltage, the operational amplifier outputs a high level to drive the transistor to conduct, thereby enabling the infrared emitting diode to operate.

[0007] Furthermore, the trigger signal generation unit includes a trigger switch SW4, the first end of which is coupled to the power input terminal, and the second end of which is used to generate a trigger signal.

[0008] Furthermore, the trigger signal generation unit also includes a first voltage divider resistor R157 and a second voltage divider resistor R156; the first end of the first voltage divider resistor R157 is coupled to the power input terminal, and the second end of the first voltage divider resistor R157 is coupled to the non-inverting input terminal of the operational amplifier through a push-button switch; the first end of the second voltage divider resistor R156 is coupled to the second end of the first voltage divider resistor R157, and the second end of the second voltage divider resistor R156 is grounded.

[0009] Furthermore, the voltage comparison unit also includes a first filtering circuit, which includes a filter capacitor C57 and a resistor R78. One end of the resistor R78 is connected to the push-button switch, and the other end is connected to the non-inverting input of the operational amplifier. Meanwhile, the other end of the resistor R78 is grounded through the filter capacitor C57.

[0010] Furthermore, the driving unit also includes a second filter circuit, which includes a resistor R102 and a capacitor C71. The first end of the resistor R102 is coupled to the output terminal of the operational amplifier, and the second end of the resistor R102 is connected to the base of the transistor through a resistor R123. In addition, the second end of the resistor R102 is also grounded through a capacitor C71.

[0011] The beneficial effects of this utility model are as follows: Fast response and reliable operation: Because the described technical solution uses a voltage comparator unit (operational amplifier) ​​as the core judgment device, it inherently possesses high gain and fast response characteristics. When the trigger signal generation unit is triggered, the circuit state (output high / low level) transitions extremely quickly, resulting in almost no delay in the switching on and off of the infrared emitting diode, thus ensuring the speed and reliability of the entire trigger circuit.

[0012] High stability and strong anti-interference capability: The voltage comparison unit effectively isolates the trigger signal generation unit from the drive unit and the infrared emitting unit. Compared with simple circuits that directly use the trigger signal to drive the switching transistor, this invention avoids interference from subsequent circuits (especially current changes generated when the infrared tube is working) on ​​the trigger signal of the preceding stage. The high input impedance and low output impedance characteristics of the operational amplifier minimize the influence between the preceding and following stages, thus resulting in higher overall operational stability.

[0013] The hardware is inexpensive and easy to manufacture and maintain: its core components are all general-purpose basic electronic components (such as operational amplifiers, switching transistors, resistors, etc.), without the need for complex application-specific integrated circuits or programmable chips. This not only significantly reduces the cost of hardware materials, but also, due to the simple circuit structure and low requirements for manufacturing processes, facilitates mass production, while also making subsequent testing, debugging, and maintenance simple and easy. Attached Figure Description

[0014] Figure 1 This is the detailed circuit diagram of the infrared trigger circuit. Detailed Implementation

[0015] Please see Figure 1 As shown, this utility model relates to an infrared triggering circuit, comprising: a power input terminal; a trigger signal generating unit for generating a trigger signal in response to an external triggering operation; a voltage comparison unit, comprising an operational amplifier U6-A, the non-inverting input terminal of the operational amplifier U6-A being coupled to the trigger signal generating unit to receive the trigger signal, and the inverting input terminal of the operational amplifier U6-A being connected to a reference voltage; and a driving unit, comprising a transistor Q7-A, the base of the transistor Q7-A being coupled to the output terminal of the operational amplifier U6-A through a resistor. The emitter of transistor Q7-A is grounded; the infrared emitting unit includes an infrared emitting diode and a current-limiting resistor. The infrared emitting diode and the current-limiting resistor are connected in series to the power input terminal, and the other end of the infrared emitting diode is coupled to the collector of transistor Q7-A; wherein, when the push-button switch is closed, the trigger signal causes the voltage at the non-inverting input terminal of operational amplifier U6-A to be higher than the reference voltage, and operational amplifier U6-A outputs a high level to drive transistor Q7-A to conduct, thereby making the infrared emitting diode work.

[0016] Because the aforementioned technical solution uses a voltage comparator unit (operational amplifier) ​​as the core judgment device, it inherently possesses high gain and fast response characteristics. When the trigger signal generation unit is triggered, the circuit state (output high / low level) transitions extremely quickly, which results in almost no delay in the switching on and off of the infrared emitting diode, thereby ensuring the speed and reliability of the entire trigger circuit.

[0017] High stability and strong anti-interference capability: The voltage comparison unit effectively isolates the trigger signal generation unit from the drive unit and the infrared emitting unit. Compared with simple circuits that directly use the trigger signal to drive the switching transistor, this invention avoids interference from subsequent circuits (especially current changes generated when the infrared tube is working) on ​​the trigger signal of the preceding stage. The high input impedance and low output impedance characteristics of the operational amplifier minimize the influence between the preceding and following stages, thus resulting in higher overall operational stability.

[0018] The hardware is inexpensive and easy to manufacture and maintain: its core components are all general-purpose basic electronic components (such as operational amplifiers, switching transistors, resistors, etc.), without the need for complex application-specific integrated circuits or programmable chips. This not only significantly reduces the cost of hardware materials, but also, due to the simple circuit structure and low requirements for manufacturing processes, facilitates mass production, while also making subsequent testing, debugging, and maintenance simple and easy.

[0019] Furthermore, the trigger signal generation unit includes a trigger switch, such as a push-button switch SW4. The first end of the trigger switch SW4 is directly coupled to the power input terminal VCC, and its second end serves as the output terminal of the trigger signal, coupled to the subsequent voltage comparison unit.

[0020] Its working principle is as follows: When the trigger switch SW4 is pressed and closed / triggered in other ways, it directly leads the high level VCC of the power input terminal to its second terminal, thereby generating a high-level trigger signal; when the trigger switch SW4 is not pressed / not triggered and is in the open state, its second terminal presents a high impedance state, and the potential at this point is determined by other circuits connected to it (such as pull-up resistors or voltage divider networks), which is usually a low level. By closing and opening the switch, a digital trigger signal corresponding to the high and low level changes of external operation can be generated.

[0021] The technical advantages of this design are as follows: Using a mechanical push-button switch as the trigger source provides a low-cost, highly reliable, and intuitive human-machine interaction method. The signal generation method is simple and direct, requiring no complex encoding or drive circuits; the response speed depends solely on the action time of the mechanical switch itself, providing the entire system with fast and clear trigger commands.

[0022] Furthermore, the trigger signal generation unit also includes a first voltage divider resistor R157 and a second voltage divider resistor R156, which, together with the trigger switch SW4, form a precise trigger signal setting network. Specifically, the first end of the first voltage divider resistor R157 is coupled to the power input terminal VCC, and its second end is directly coupled to the non-inverting input terminal (V+) of the operational amplifier U6-AU6-A. The first end of the second voltage divider resistor R156 is coupled to the second end (i.e., the V+ point) of the first voltage divider resistor R157, and its second end is grounded. The push-button switch SW4 is connected in parallel with the first voltage divider resistor R157.

[0023] By precisely proportioning the voltage divider resistors, a stable and deterministic low voltage value is established for the "untriggered" state, avoiding false triggering caused by line noise or interference and greatly improving circuit reliability. The simple mechanical switching action is transformed into a predictable and calculable voltage comparison problem, making the circuit behavior entirely determined by component parameters, resulting in better consistency and repeatability. Engineers can easily adjust the values ​​of R157 and R156 to adapt to different power supply voltages or comparator reference voltages, making this circuit architecture more versatile.

[0024] Furthermore, the voltage comparison unit also includes a first filtering circuit, which includes a filter capacitor C57 and a resistor R78. One end of the resistor R78 is connected to the push-button switch, and the other end is connected to the non-inverting input of the operational amplifier U6-A. Meanwhile, the other end of the resistor R78 is grounded through the filter capacitor C57.

[0025] Its working principle lies in the fact that the first filter circuit forms an RC low-pass filter network, which directly acts on the trigger signal path. When the push-button switch SW4 is closed, generating a trigger signal with a sudden voltage change, the filter network can effectively smooth the spikes and glitches of the signal rising edge and absorb high-frequency interference that may be introduced by the leads. Resistor R78 limits the instantaneous charging current, while capacitor C57 provides charge storage and buffering, together making the trigger signal applied to the non-inverting input (V+) of operational amplifier U6-A purer and more stable, avoiding misjudgment by the voltage comparator due to signal jitter or instantaneous overshoot.

[0026] Its effect is as follows: by shaping and filtering the trigger signal, potential instantaneous interference pulses are eliminated, ensuring the accuracy and reliability of the trigger command. Especially in application scenarios with complex electromagnetic environments, this filtering circuit can effectively suppress interference caused by spatial coupling or power fluctuations on sensitive signal input lines, improving system stability. In addition, it provides a guarantee of a clean and stable comparison input voltage (V+), which, together with a stable reference voltage (V-), ensures the accuracy of the voltage comparison unit's judgment result.

[0027] Furthermore, the driving unit also includes a second filter circuit, which includes a resistor R102 and a capacitor C71. The first end of the resistor R102 is coupled to the output terminal of the operational amplifier U6-A, and the second end of the resistor R102 is connected to the base of the transistor Q7-A through a resistor R123. In addition, the second end of the resistor R102 is also grounded through a capacitor C71.

[0028] Furthermore, the driving unit also includes a signal conditioning circuit (i.e., a second filter circuit), which includes a resistor R102 and a capacitor C71. The first end of resistor R102 is directly coupled to the output of operational amplifier U6-A to receive its output control level; the second end of resistor R102 is connected to the base of transistor Q7-A through resistor R123, and grounded through capacitor C71. Its core working principle is that this RC network forms a low-pass filter. When the output level of operational amplifier U6-A changes (e.g., from low to high), capacitor C71 charges through resistor R102. The voltage across C71 cannot change abruptly, resulting in a slow rise in the voltage applied to the base of transistor Q7-A, rather than a steep transition edge. This delays the transistor's transition from cutoff to saturation. When the output level of operational amplifier U6-A changes again (e.g., from high level to low level), capacitor C71 discharges through resistor R102 and the op-amp output circuit, which also causes the base voltage of the transistor to drop slowly, delaying the transistor's turn-off process from conduction to cutoff.

[0029] The key technical benefit of this design is that the circuit can significantly attenuate extremely fast transient interference or high-frequency noise that may exist on the control signal path. Because of their high frequency, most of these brief glitches are bypassed to ground by capacitor C71, preventing them from reaching the voltage amplitude and duration sufficient to turn on transistor Q7-A. This avoids false turn-on due to interference and greatly enhances the circuit's anti-interference capability.

[0030] The turn-on and turn-off times of transistor Q7-A were artificially extended. This reduces electromagnetic interference (EMI) generated during switching, allowing the circuit to meet stricter electromagnetic compatibility requirements. Furthermore, for capacitive loads or specific applications, the smooth switching characteristics prevent current surges, protecting transistor Q7-A and the infrared emitter. By smoothing and filtering the drive signal, the switching of transistor Q7-A's operating state is ensured to be clear and stable, avoiding frequent jitter at critical points, thus making the infrared light emission control more reliable and deterministic.

[0031] The specific working principle of this utility model is as follows, combined with Figure 1 The illustrated embodiment uses a power supply voltage of VCC = +5V as an example for explanation: 1. Standby State (Button SW4 Off): In this state, the first voltage divider resistor R157 and the second voltage divider resistor R156 in the trigger signal generation unit are connected in series to form a voltage divider network. The voltage at the non-inverting input (V+) of operational amplifier U6-AU6-A is entirely determined by this network. By configuring the resistance ratio of R157 and R156 (for example, making the voltage divider ratio 0.5), the voltage at point V+ can be stabilized at a specific low level (e.g., 2.5V). This voltage is set lower than the reference voltage (V_ref) at the inverting input (V-) of operational amplifier U6-A. Since V+ < V-, the voltage comparator (U6-A) outputs a low level (Vo ≈ 0V). This low level causes the base-emitter voltage Vbe of transistor Q7-A in the driver unit to be < 0.7V, and the transistor therefore operates in the cutoff region, with its collector-emitter junction effectively open. At this time, no working current flows through the infrared emitting unit (LED4 and the current-limiting resistor R123 in series branch) (I_c ≈ 0), the infrared emitting diode LED4 does not emit light, and the circuit is in static standby mode.

[0032] 2. Trigger State (Button SW4 Closed): When button SW4 is pressed and closed, it short-circuits resistor R156. At this time, the power supply VCC (+5V) is directly connected to the non-inverting input (V+) of operational amplifier U6-A through resistor R157. The voltage at V+ is quickly pulled up to a high level (typically about 4.5V). At this time, V+ > V-, and the output state of the voltage comparator flips instantaneously, outputting a high level (Vo ≈ VCC = +5V). This high level drives transistor Q7-A through the base resistor (such as R102) in the driver unit, causing it to enter the saturation conduction region. At this time, the collector-emitter junction of the transistor is equivalent to a closed small resistive switch, thus forming a complete current loop: VCC → infrared emitting diode LED4 → current-limiting resistor R123 → transistor Q7-A(ce) → GND. The infrared emitting diode LED4 receives its rated operating current (set by the current-limiting resistor R123), is lit, and emits infrared light of a specific wavelength.

[0033] 3. Summary of core working mechanisms: The core of this circuit lies in using a voltage comparator to compare two analog voltages (V+ and V-) in real time, and converting the comparison result into a digital switching output signal (high / low level). This signal is then used to control the operating state of the infrared emitting diode via a transistor switch. The action of button SW4 essentially changes the voltage at point V+, thus disrupting the comparator's original balance and triggering a state reversal throughout the circuit. This design achieves the control of a relatively large current power load using a small analog voltage comparison, combining control precision with drive reliability.

[0034] The above embodiments are merely preferred embodiments of the present utility model and are not intended to limit the scope of the present utility model. Various modifications and improvements made to the technical solutions of the present utility model by those skilled in the art without departing from the spirit of the present utility model should fall within the protection scope defined by the claims of the present utility model.

Claims

1. An infrared triggering circuit, characterized in that, include: Power input terminal; A trigger signal generation unit is used to generate a trigger signal in response to an external trigger operation; A voltage comparison unit includes an operational amplifier, the non-inverting input of which is coupled to the trigger signal generation unit to receive the trigger signal, and the inverting input of which is connected to a reference voltage. A driving unit includes a transistor, the base of which is coupled to the output of the operational amplifier through a resistor, and the emitter of which is grounded. An infrared emitting unit includes an infrared emitting diode and a current-limiting resistor. The infrared emitting diode and the current-limiting resistor are connected in series to the power input terminal, and the other end of the infrared emitting diode is coupled to the collector of the transistor. The trigger signal generation unit generates a trigger signal, which causes the voltage at the non-inverting input terminal of the operational amplifier to be higher than the reference voltage. The operational amplifier outputs a high level to drive the transistor to conduct, thereby enabling the infrared emitting diode to work.

2. The infrared triggering circuit according to claim 1, characterized in that, The trigger signal generation unit includes a trigger switch SW4, the first end of which is coupled to the power input terminal, and the second end of which is used to generate a trigger signal.

3. The infrared triggering circuit according to claim 1, characterized in that, The trigger signal generation unit further includes a first voltage divider resistor R157 and a second voltage divider resistor R156; the first end of the first voltage divider resistor R157 is coupled to the power input terminal, and the second end of the first voltage divider resistor R157 is coupled to the non-inverting input terminal of the operational amplifier through a push-button switch; the first end of the second voltage divider resistor R156 is coupled to the second end of the first voltage divider resistor R157, and the second end of the second voltage divider resistor R156 is grounded.

4. An infrared triggering circuit according to claim 3, characterized in that, The voltage comparison unit further includes a first filtering circuit, which includes a filter capacitor C57 and a resistor R78. One end of the resistor R78 is connected to the push-button switch, and the other end is connected to the non-inverting input of the operational amplifier. Meanwhile, the other end of the resistor R78 is grounded through the filter capacitor C57.

5. An infrared triggering circuit according to claim 4, characterized in that, The driving unit also includes a second filtering circuit, which includes a resistor R102 and a capacitor C71. The first end of the resistor R102 is coupled to the output of the operational amplifier, and the second end of the resistor R102 is connected to the base of the transistor through a resistor R123. In addition, the second end of the resistor R102 is also grounded through a capacitor C71.

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