Infrared detection alarm circuit for camera equipment

Abstract

The utility model relates to the technical field of camera shooting equipment, and discloses an infrared detection alarm circuit for camera shooting equipment, which aims to solve the technical problem that the alarm time of the conventional product is short and is easily neglected, and is characterized in that the anode of a fourth diode is connected with the inverted input end of a second voltage comparator; the cathode of the fourth diode is connected with the output end of the first voltage comparator, the anode of the fourth diode is grounded through a first electrolytic capacitor, and second direct current is input into the anode of the fourth diode through a first pull-up resistor; a series resistance voltage division circuit providing reference voltage for the in-phase input end of a second voltage comparator is arranged, the output end of the second voltage comparator is connected with the base electrode of a third triode through a first current limiting resistor, the emitter electrode of the third triode is grounded, and the collector electrode of the third triode is connected with the first end of a buzzer. Delayed triggering and continuous output of alarm signals are achieved, and the problems that an existing product is short in alarm time and not prone to causing attention are effectively solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of camera equipment, and particularly relates to an infrared detection alarm circuit for camera equipment. BACKGROUND

[0002] Cameras have a wide range of applications in various scenarios, mainly for real-time monitoring to improve overall safety management. Some cameras also have audio alarm functions, but existing such cameras have certain limitations, with short alarm duration and difficulty in attracting attention.

[0003] Under normal circumstances, the alarm trigger duration is short, and the sound and light prompts may only last for a few seconds, which will affect the effective dissemination of the alarm to some extent. Especially in a busy work environment, the short alarm sound is easily covered or ignored by background noise, causing the staff to fail to timely perceive the alarm information, and thus the disposal of abnormal situations may be delayed. These problems limit the full play of the camera system in some scenarios.

[0004] Therefore, although the camera plays an important role in safety management, its technology and function still need to be optimized to better meet the actual needs and work requirements in complex scenarios. CONTENT OF THE UTILITY MODEL

[0005] The utility model aims at providing an infrared detection alarm circuit for camera equipment to solve the technical problem of short alarm time of the existing products.

[0006] To achieve the above-mentioned purpose, the specific technical scheme of the infrared detection alarm circuit for camera equipment of the utility model is as follows:

[0007] An infrared detection alarm circuit for camera equipment, comprising an infrared sensor for detecting and outputting a sensing signal, an amplification circuit for amplifying the sensing signal, and a first voltage comparator for comparing the amplified sensing signal with a reference voltage, provided with a second voltage comparator and a fourth diode, the anode of the fourth diode being connected with the inverting input end of the second voltage comparator, the cathode of the fourth diode being connected with the output end of the first voltage comparator, the anode of the fourth diode being grounded through a first electrolytic capacitor, and the anode of the fourth diode inputting a second direct current through a first pull-up resistor; provided with a series resistance voltage dividing circuit for providing a reference voltage to the non-inverting input end of the second voltage comparator, the output end of the second voltage comparator being connected with the base of a third transistor through a first current limiting resistor, the emitter of the third transistor being grounded, the collector of the third transistor being connected with the first end of a buzzer, the second end of the buzzer inputting a first direct current source, and the third transistor being an NPN type transistor.

[0008] By setting the first voltage comparator and the second voltage comparator, in combination with the fourth diode, the resistance voltage dividing circuit and the delay circuit, the delay triggering and the continuous output of the alarm signal are realized, and the problems of short alarm time and difficulty in attracting attention of the existing products are effectively solved.The first voltage comparator is used for preliminarily processing the infrared induction signal, when the induction signal exceeds the reference voltage, the output state of the first voltage comparator is switched, the delay circuit is formed through the fourth diode and the first electrolytic capacitor, the slowly changing voltage is provided to the inverting input end of the second voltage comparator, the alarm signal can be ensured to last for a certain time, and the second voltage comparator is used for driving the third triode to make the buzzer emit the alarm sound.The alarm sound duration of the buzzer is determined by the parameters of the delay circuit, and the alarm sound is about 1 minute by the optimal design, the propagation effect of the alarm signal is obviously enhanced, the problem that the short alarm sound is covered or ignored due to the background noise is avoided, and the warning ability and the safety management level of the camera equipment system in a complex scene are obviously improved.

[0009] Further, the output end of the second voltage comparator is connected with the collector of the second triode in sequence through the second current-limiting resistor and the fifth diode, the emitter of the second triode is grounded, the base of the second triode is connected with the cathode of the second diode through the third current-limiting resistor, the anode of the second diode is grounded, the cathode of the second diode inputs the first direct current through the second electrolytic capacitor, and the second triode is an NPN type triode.

[0010] Further, the amplification circuit comprises a first-stage amplification circuit and a second-stage amplification circuit for amplifying the induction signal, the first-stage amplification circuit comprises a first triode, the base of the first triode is connected with the signal output end of the infrared sensor through the first coupling capacitor, the emitter of the first triode is grounded, and the collector of the first triode inputs the second direct current through the second pull-up resistor; the second-stage amplification circuit comprises an operational amplifier, the noninverting input end of the operational amplifier is connected with the collector of the first triode through the second coupling capacitor, and the output end of the operational amplifier is connected with the inverting input end of the first voltage comparator through the third coupling capacitor.

[0011] Further, the power supply circuit is provided with a transformer for AC voltage reduction, a rectifier circuit for converting AC into DC, and a filter circuit, the first direct current is formed after filtering, the second direct current is output after the first direct current passes through a linear voltage reducer, and the operational amplifier, the infrared sensor, the first voltage comparator and the second voltage comparator are powered.

[0012] The infrared detection alarm circuit for the camera equipment has the following advantages:

[0013] When the signal voltage outputted by the operational amplifier reaches the voltage of the inverting input terminal of the first voltage comparator, the voltage comparison is performed, and the state of the output terminal of the first voltage comparator is switched from high level to low level.

[0014] The second voltage comparator is used for the alarm delay circuit, and the delay time of the delay circuit composed of the first pull-up resistor and the first electrolytic capacitor is about 1 minute, and the length of time can be determined according to the capacity of the adjusting capacitor. When the output of the first voltage comparator is low level, the first electrolytic capacitor is discharged through the fourth diode, so that the voltage of the inverting input terminal of the second voltage comparator is reduced, and compared with the reference voltage of the same-phase input terminal. When the voltage of the inverting input terminal is lower than the reference voltage, the output terminal of the second voltage comparator becomes high level, and the third triode is triggered to be turned on, so that the buzzer is activated and emits an alarm sound. When the human body infrared signal disappears, the output terminal of the first voltage comparator returns to high level state, and the fourth diode is cut off. Since the voltage change of the first electrolytic capacitor needs a certain time, the first pull-up resistor is used to slowly charge the first electrolytic capacitor, until the voltage between the two ends of the first electrolytic capacitor is higher than the reference voltage again, the output terminal of the second voltage comparator becomes low level, and the alarm sound stops after about 1 minute. Thus, the delay effect is realized. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 A power supply circuit diagram is provided for the utility model;

[0016] Figure 2 An infrared induction and signal amplification circuit diagram is provided for the utility model;

[0017] Figure 3 A delay and alarm circuit diagram is provided for the utility model.

[0018] In the figure: U1, operational amplifier; U2, infrared inductor; U3, first voltage comparator; U5, second voltage comparator; U6, linear voltage reducer; SP, buzzer; T2, transformer; DC1, first direct current; DC2, second direct current; D1, first diode; D2, second diode; D3, third diode; D4, fourth diode; D5, third diode; C7, first coupling capacitor; C8, second coupling capacitor; C11, third coupling capacitor; R16, first pull-up resistor; R3, second pull-up resistor; R19, first current-limiting resistor; R20, second current-limiting resistor; R21, third current-limiting resistor; C13, first electrolytic capacitor; C14, second electrolytic capacitor; Q1, first triode; Q2, second triode; Q3, third triode. DETAILED DESCRIPTION

[0019] In order to make the utility model's purpose, technical scheme and advantage more clearly, the following will be further detailed with the drawings and examples. It should be understood that the specific examples described here are only to explain the utility model, and are not used to limit the utility model.

[0020] Referring to Figure 1 and Figure 2 The utility model provides a kind of infrared detection alarm circuit for camera equipment, including power supply circuit, power supply circuit is provided with the transformer T2 for voltage reduction, after reducing the voltage of alternating current, rectifier circuit formed by four diodes is rectified, and the pulsating direct current is output to the filter circuit of subsequent stage for filtering, then form first direct current DC1 and output to linear voltage reducer U6, and linear voltage reducer U6 outputs second direct current DC2, for power supply to operational amplifier U1, infrared sensor U2, first voltage comparator U3 and second voltage comparator U5.Infrared sensor U2 is embedded in camera equipment, and is dedicated to infrared detection.

[0021] Battery BAT1 and diode D1 are provided, the negative pole of battery BAT1 is grounded, the positive pole of battery BAT1 is connected with the anode of diode D1, and the cathode of diode D1 is connected with the output end of rectifier circuit. Thus realize AC and DC dual-purpose, achieve uninterrupted conversion.

[0022] Referring to Figure 2 , the signal output end of infrared sensor U2 is connected with the base of triode Q1 through coupling capacitor C7, triode Q1 is NPN triode, the emitter of triode Q1 is grounded, the collector of triode Q1 is input with second direct current DC2 through pull-up resistor R3, the collector of triode Q1 is connected with the noninverting input end of operational amplifier U1 in turn through coupling capacitor C7 and resistor R4, the noninverting input end of operational amplifier U1 is grounded in turn through resistor R7 and capacitor C10, and the output end of operational amplifier U1 is connected with the noninverting input end of first voltage comparator U3 through coupling capacitor C11.

[0023] The noninverting input end of first voltage comparator U3 is connected with resistor R11 and diode D3 in turn, and resistor R11 is used to input second direct current DC2, the cathode of diode D3 is grounded, and the anode of diode D3 is connected with the noninverting input end of first voltage comparator U3, and resistor R11 and diode D3 form reference voltage circuit to provide voltage to the noninverting input end of first voltage comparator U3.

[0024] The output terminal of the first voltage comparator U3 is connected with the inverting input terminal of the second voltage comparator U5 through a diode D4, the anode of the diode D4 is connected with the inverting input terminal of the second voltage comparator U5, the cathode of the diode D4 is connected with the output terminal of the first voltage comparator U3, the anode of the diode D4 is grounded through a capacitor C13, and the anode of the diode D4 is inputted with the second direct current DC2 through a resistor R16.

[0025] A series resistor voltage dividing circuit is arranged to provide a reference voltage to the non-inverting input terminal of the second voltage comparator U5, the series resistor voltage dividing circuit is composed of a resistor R14 and a resistor R15, the upper end of the series resistor voltage dividing circuit is inputted with the second direct current DC2, and the lower end of the series resistor voltage dividing circuit is grounded.

[0026] The output terminal of the second voltage comparator U5 is connected with the base of a triode Q3 through a resistor R19, the emitter of the triode Q3 is grounded, the collector of the triode Q3 is connected with the first end of a buzzer SP, and the second end of the buzzer SP is inputted with the first direct current DC1.

[0027] The output terminal of the second voltage comparator U5 is connected with the collector of a triode Q2 in sequence through a resistor R20 and a diode D5, the emitter of the triode Q2 is grounded, the base of the triode Q2 is connected with the cathode of a diode D2 through a resistor R21, the anode of the diode D2 is grounded, and the cathode of the diode D2 is inputted with the first direct current DC1 through a capacitor C14. The capacitor C14 is an electrolytic capacitor, and realizes time delay through charging and discharging, and the capacity value of the capacitor C14 is preferably 47uF.

[0028] Working principle:

[0029] After the infrared sensor U2 detects the infrared signal radiated by the human body, a weak electric signal is outputted from the second end of the infrared sensor U2, the signal is preliminarily amplified through the first-stage amplification circuit composed of the triode Q1, and then is transmitted to the second-stage amplification circuit composed of the operational amplifier U1 through the coupling capacitor C8 to realize high-gain and low-noise secondary amplification. At this time, the output signal of the operational amplifier U1 is already strong enough.

[0030] The first voltage comparator U3 sets the reference voltage by using the resistor R11 and the diode D3, when the signal voltage outputted by the operational amplifier U1 reaches the voltage of the inverting input terminal of the first voltage comparator U3, the voltage comparison is performed, and the state of the output terminal of the first voltage comparator U3 is switched from high level to low level.

[0031] The second voltage comparator U5 is used for the alarm delay circuit, the resistance R16 and the capacitor C13 constitute a delay circuit, the capacitor C13 is an electrolytic capacitor, preferably a 47uF capacitor, and the delay time is about 1 minute, and the time length can be adjusted according to the capacity of the capacitor.When the first voltage comparator U3 outputs a low level, the capacitor C13 is discharged through the diode D4, causing the level of the inverting input end of the second voltage comparator U4 to decrease, and compared with the reference voltage of the same phase input end thereof.When the inverting input level is lower than the reference voltage, the output end of the second voltage comparator U4 becomes a high level, triggering the triode Q3 to turn on, and the buzzer SP is activated and emits an alarm sound.

[0032] When the human body infrared signal disappears, the output end of the first voltage comparator U3 returns to a high level state, and the diode D4 is cut off.Because the voltage change of the capacitor C13 needs a certain time, it is slowly charged through the resistance R14, until the voltage between the capacitor C13 is higher than the reference voltage again, the output end of the second voltage comparator U5 becomes a low level, and the alarm sound stops after about 1 minute.

[0033] In addition, the triode Q2, the resistance R21 and the capacitor C14 constitute a start-up delay circuit, and the delay is about 1 minute, avoiding triggering the alarm immediately after starting up or power failure and re-powering, and providing sufficient time for the user to leave the monitoring area, while effectively preventing false alarms.

[0034] The infrared detection alarm circuit for the camera equipment has the following advantages:

[0035] The infrared detection alarm circuit realizes high-sensitivity detection, accurate determination and alarm delay function of the human body infrared signal through the combination of the hierarchical amplification design and the double voltage comparators.The high-gain, low-noise amplification circuit composed of the first-stage triode amplification circuit and the second-stage operational amplifier significantly enhances the strength of the weak signal, ensuring the reliability of the signal detection;the first voltage comparator accurately judges the signal effectiveness and rapidly triggers the alarm logic by setting the reference voltage, and in combination with the second voltage comparator and the delay circuit, the alarm delay function is realized through the delay charging and discharging characteristics of the resistance and the capacitor, avoiding false alarms caused by temporary signal fluctuations;in addition, the start-up delay circuit provides a certain delay time when starting up or power failure and power recovery, preventing false alarms and giving the user sufficient time to prepare, improving the use experience and system stability.The overall circuit design has the characteristics of sensitive detection, accurate alarm, adjustable delay and strong anti-false alarm capability, and is suitable for real-time monitoring and efficient alarm of abnormal human body infrared signals in the camera equipment system.

[0036] The above only describes the preferred embodiments of the utility model, and does not limit the utility model, and any modification, equivalent replacement and improvement made within the spirit and principle of the utility model should be included in the protection scope of the utility model.

Claims

1. An infrared ray detecting alarm circuit for a video camera, comprising an infrared sensor (U2) for detecting and outputting a sensing signal, an amplifying circuit for amplifying the sensing signal, and a first voltage comparator (U3) for comparing the amplified sensing signal with a reference voltage, characterized in that, The second voltage comparator (U5) and the fourth diode (D4) are arranged, the anode of the fourth diode (D4) is connected with the non-inverting input end of the second voltage comparator (U5), the cathode of the fourth diode (D4) is connected with the output end of the first voltage comparator (U3), the anode of the fourth diode (D4) is grounded through the first electrolytic capacitor (C13), and the anode of the fourth diode (D4) is input with the second direct current (DC2) through the first pull-up resistor (R16); The series resistance voltage dividing circuit for providing the reference voltage to the non-inverting input end of the second voltage comparator (U5) is arranged, the output end of the second voltage comparator (U5) is connected with the base of the third transistor (Q3) through the first current limiting resistor (R19), the emitter of the third transistor (Q3) is grounded, the collector of the third transistor (Q3) is connected with the first end of the buzzer (SP), the second end of the buzzer (SP) is connected with the first direct current (DC1) source, and the third transistor (Q3) is an NPN type transistor.

2. The infrared detection alarm circuit for a video camera according to claim 1, wherein The output end of the second voltage comparator (U5) is connected with the collector of the second transistor (Q2) in sequence through the second current limiting resistor (R20), the fifth diode and the second transistor (Q2), the emitter of the second transistor (Q2) is grounded, the base of the second transistor (Q2) is connected with the cathode of the second diode (D2) through the third current limiting resistor (R21), the anode of the second diode (D2) is grounded, the cathode of the second diode (D2) is input with the first direct current (DC1) through the second electrolytic capacitor (C14), and the second transistor (Q2) is an NPN type transistor.

3. The infrared detection alarm circuit for a video camera according to claim 2, wherein The amplification circuit comprises a first-stage amplification circuit and a second-stage amplification circuit for amplifying the induction signal, the first-stage amplification circuit comprises a first transistor (Q1), the base of the first transistor (Q1) is connected with the signal output end of the infrared inductor (U2) through the first coupling capacitor (C7), the emitter of the first transistor (Q1) is grounded, and the collector of the first transistor (Q1) is input with the second direct current (DC2) through the second pull-up resistor (R3); the second-stage amplification circuit comprises an operational amplifier (U1), the non-inverting input end of the operational amplifier (U1) is connected with the collector of the first transistor (Q1) through the second coupling capacitor (C8), and the output end of the operational amplifier (U1) is connected with the non-inverting input end of the first voltage comparator (U3) through the third coupling capacitor (C11).

4. The infrared detection alarm circuit for a video camera according to claim 3, wherein The power supply circuit is provided with a transformer (T2) for AC voltage reduction, a rectifier circuit for converting AC into DC, and a filter circuit, and the first direct current (DC1) is formed after filtering, the second direct current (DC2) is output after the first direct current (DC1) passes through the linear voltage reducer (U6), and the operational amplifier (U1), the infrared inductor (U2), the first voltage comparator (U3) and the second voltage comparator (U5) are powered.

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