An LED lamp test circuit

Abstract

The utility model discloses a kind of LED lamp test circuit, it is related to LED lamp detection technical field.The circuit includes heating device, timing circuit, light detection circuit, temperature detection circuit and current detection circuit, to be measured LED lamp is located in heating device, is supplied by triode Q1 and cathode ground connection.Wherein, timing circuit is composed of 555 timer, timer and 74LS85 chip, can preset test duration and automatically power off;Light detection circuit monitors brightness by photosensitive resistance and comparator, temperature detection circuit uses NTC temperature control resistance to collect lamp body temperature, current detection circuit is connected in parallel in LED lamp both ends monitoring current, three are equipped with slide rheostat and adjust threshold value, corresponding warning light is lit and power supply is cut off when abnormal.The circuit has no complex integrated module, low in cost, simple structure, can realize environment simulation, multi-parameter detection and abnormal protection synchronously, adapt to different LED lamp test demand, conducive to production line deployment and maintenance.

Description

Technical Field

[0001] This utility model relates to the field of LED lamp testing technology, and in particular to an LED lamp testing circuit. Background Technology

[0002] In the field of LED lamp production and quality inspection, companies' core requirements for testing equipment focus on three main dimensions: cost control, ease of operation, and comprehensive functional coverage. However, existing LED lamp testing solutions generally have problems;

[0003] Some devices with multi-parameter detection capabilities rely on imported chips or complex integrated modules, with the cost of a single device reaching tens of thousands of yuan, which is difficult for small and medium-sized manufacturers to afford. At the same time, the devices require regular maintenance and calibration, which further increases the subsequent operation and maintenance costs. Moreover, the circuit wiring is cumbersome, which is not conducive to the rapid deployment of production lines. Some low-cost testing devices can only detect a single parameter and cannot simultaneously verify the comprehensive performance of LED lights. Utility Model Content

[0004] The technical problem to be solved by this utility model is to provide an LED lamp test circuit that is low in cost, simple in structure, and has comprehensive functions.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows:

[0006] The key to an LED lamp testing circuit lies in...

[0007] It includes a heating device, a timing circuit, a light detection circuit, a temperature detection circuit, and a current detection circuit;

[0008] The light detection circuit is connected to the LED under test via an optocoupler; the temperature detection circuit is connected via a thermistor attached to the surface of the LED under test; the current detection circuit is connected in parallel across the two ends of the LED under test; the timing circuit is connected to the power supply terminal of the LED under test; and the LED under test is housed within the heating device.

[0009] The LED under test, LED1, is powered by transistor Q1, and the negative terminal of LED1 is grounded.

[0010] Preferably, the timing circuit includes a 555 timer U5, a timer U6, and a timing chip U4;

[0011] The 555 timer outputs a square wave of a fixed frequency through an external connection. U6 receives the square wave output by U5 and counts it. The timing is performed by cascading. The timing chip U4 uses a 74LS85 chip and includes 4 pairs of comparison terminals. The test time is set by presetting the B0-B3 pins of the 4 pairs of comparison terminals. The output terminal of the OA=B pin of U4 is connected to the gate of the PMOS transistor Q2.

[0012] The drain of Q2 is connected to the base of Q1, and the source of Q2 is connected to the power supply via button K1.

[0013] Preferably, the light detection circuit includes a photoresistor R1, a voltage divider resistor R6, a comparator U1, a comparator U8, resistors R7 and R8, a thyristor Q8, and a sliding rheostat RP1.

[0014] The photoresistor R1 and the voltage divider resistor R6 form a voltage divider network. One end of R6 is connected to the source of Q2 to obtain the power supply voltage. The voltage across R1 is sampled and amplified by comparator U1. The output of U1 is connected to the non-inverting comparator of U8. The inverting comparator of U8 is connected to a preset voltage composed of RP1 and the power supply. The output of U8 is connected to the control terminal of Q8. The positive terminal of Q8 is connected to the source of Q2. The negative terminal of Q8 is connected to the positive terminal of the warning light LED4. The negative terminal of LED4 is connected to the gate of PMOS transistor Q2.

[0015] Preferably, the temperature detection circuit includes a temperature control resistor NTC, a voltage divider resistor R9, a comparator U3, a comparator U7, resistors R10 and R11, a thyristor Q6, and a sliding rheostat RP2.

[0016] The temperature control resistor NTC and the voltage divider resistor R9 form a voltage divider network. One end of R9 is connected to the source of Q2 to obtain the power supply voltage. The voltage across the temperature control resistor NTC is sampled and amplified by comparator U3. The output of U3 is connected to the non-inverting comparator of U7. The inverting comparator of U7 is connected to the preset voltage composed of RP2 and the power supply. The output of U7 is connected to the control terminal of Q6. The positive terminal of Q6 is connected to the source of Q2. The negative terminal of Q6 is connected to the positive terminal of the warning light LED3. The negative terminal of LED3 is connected to the gate of PMOS transistor Q2.

[0017] Preferably, the current detection circuit is connected in parallel across the two ends of the LED lamp LED1 under test, and includes comparator U2, comparator U9, thyristor Q7 and sliding rheostat RP3;

[0018] The positive terminal of LED1 is connected to resistor R5 and the non-inverting comparison terminal of comparator U2 via resistor R2, and the other end of R5 is grounded. The negative terminal of LED1 is connected to one end of resistor R4 and the inverting comparison terminal of U2 via resistor R3. The output terminal of U2 is connected to the other end of R4 and the non-inverting comparison terminal of comparator U9. The inverting comparison terminal of U9 is connected to a preset voltage composed of sliding rheostat RP3 and power supply. The output terminal of U9 is connected to the control terminal of Q7. The positive terminal of Q7 is connected to the source of Q2, the negative terminal of Q7 is connected to the positive terminal of warning light LED2, and the negative terminal of LED2 is connected to the gate of PMOS transistor Q2.

[0019] The beneficial effects of adopting the above technical solution are as follows:

[0020] This invention integrates multi-parameter detection and anomaly protection under environmental simulation by combining a timing circuit with multiple detection circuits. It has comprehensive functions, and the detection circuit has no integrated modules, which reduces circuit complexity, facilitates later debugging and maintenance, and reduces circuit costs. Attached Figure Description

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0022] Figure 1 This is a partial circuit diagram of an LED lamp testing circuit proposed in this utility model;

[0023] Figure 2 This is a schematic diagram of the light detection circuit of an LED lamp testing circuit proposed in this utility model. Detailed Implementation

[0024] The technical solutions of this utility model will be clearly and completely described below with reference to the embodiments of this utility model. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this utility model.

[0025] An LED lamp test circuit, such as Figure 1-2 It includes a heating device, a timing circuit, a light detection circuit, a temperature detection circuit, and a current detection circuit; the heating device provides constant temperature conditions for the test circuit and provides the test environment.

[0026] The light detection circuit is connected to the LED under test via an optocoupler; the temperature detection circuit is connected via a thermistor attached to the surface of the LED under test; the current detection circuit is connected in parallel across the two ends of the LED under test; the timing circuit is connected to the power supply terminal of the LED under test; the LED under test is placed inside the heating device; the LED under test LED1 is powered by transistor Q1, and the negative terminal of LED1 is grounded.

[0027] Regarding the working environment of LED lights, the most critical external environmental factor affecting the lifespan and performance of LED lights is temperature. This application controls the external temperature through a heating device, and then uses various detection circuits to perform power-on tests on the LED lights under test for a preset duration, thereby realizing the functional testing of LED lights.

[0028] In this embodiment, the heating device provides protection for the external environment by using a hot air blower or a constant temperature chamber to achieve stable control of the external temperature. The timing circuit then presets the test time. The light detection circuit combines a photoresistor and the LED under test in a form similar to an optocoupler. When the LED fails to light up or its brightness is insufficient, the corresponding warning light is lit. The temperature detection circuit collects temperature information through a temperature control resistor attached to the surface of the LED. The current detection circuit detects whether the operating current of the LED is stable.

[0029] The timing circuit includes a 555 timer U5, a timer U6, and a timing chip U4. The 555 timer outputs a square wave of a fixed frequency through an external connection. U6 receives the square wave output by U5 and counts it. The timing is performed by cascading. The timing chip U4 uses a 74LS85 chip and includes four pairs of comparison terminals. The test time is set by presetting the B0-B3 pins of the four comparison terminals. The output terminal of the OA=B pin of U4 is connected to the gate of PMOS transistor Q2. The drain of Q2 is connected to the base of Q1, and the source of Q2 is connected to the power supply through button K1.

[0030] A fixed-frequency square wave is output by a 555 timer, which is counted by timer chip U6. Different number systems and time counting are performed by frequency division and cascading. The output terminals are then connected to timer chip U4. Timer chip U4 performs threshold control on the information output by the counter through bit comparison. When the preset threshold is reached, a high-level signal is output to control Q2 to turn off, which in turn turns off Q1. This realizes the timing test function of the LED lamp under test.

[0031] The timer presets the time by using the cascaded and frequency-divided timer U6 in conjunction with the B0-B3 pins of the preset comparison terminal of U4 to achieve a fixed-time test.

[0032] K1 is the test button. When K1 is turned on, each test circuit obtains the power supply voltage and starts working.

[0033] The light detection circuit includes a photoresistor R1, a voltage divider resistor R6, a comparator U1, a comparator U8, resistors R7 and R8, a thyristor Q8, and a sliding rheostat RP1.

[0034] A photoresistor R1 and a voltage divider resistor R6 form a voltage divider network. One end of R6 is connected to the source of Q2 to obtain the power supply voltage. The voltage across R1 is sampled and amplified by comparator U1. The output of U1 is connected to the non-inverting comparator of U8. The inverting comparator of U8 is connected to the preset voltage composed of RP1 and the power supply. The output of U8 is connected to the control terminal of Q8. The positive terminal of Q8 is connected to the source of Q2. The negative terminal of Q8 is connected to the positive terminal of the warning light LED4. The negative terminal of LED4 is connected to the gate of the PMOS transistor Q2.

[0035] The brightness detection circuit captures the brightness information of the LED under test through the voltage division of the photoresistor R1. When the brightness is insufficient, the voltage division of R1 increases, the output voltage of U1 increases, and when it exceeds the threshold voltage set at the inverting comparison terminal of U8, U8 outputs a high level, turns on Q8, and LED4 lights up. Due to the latching function of Q8, it ensures a constant-on warning, thereby turning off Q2 and Q1, and shutting off the test power supply of the LED under test.

[0036] The temperature detection circuit includes a temperature control resistor NTC, a voltage divider resistor R9, a comparator U3, a comparator U7, resistors R10 and R11, a thyristor Q6, and a sliding rheostat RP2.

[0037] The temperature control resistor NTC and the voltage divider resistor R9 form a voltage divider network. One end of R9 is connected to the source of Q2 to obtain the power supply voltage. The voltage across the temperature control resistor NTC is sampled and amplified by comparator U3. The output of U3 is connected to the non-inverting comparator of U7. The inverting comparator of U7 is connected to the preset voltage composed of RP2 and the power supply. The output of U7 is connected to the control terminal of Q6. The positive terminal of Q6 is connected to the source of Q2. The negative terminal of Q6 is connected to the positive terminal of the warning light LED3. The negative terminal of LED3 is connected to the gate of PMOS transistor Q2.

[0038] The temperature detection circuit obtains the surface temperature information of the LED under test through the temperature control resistor NTC. When the temperature is too high, the output voltage of U3 exceeds the preset threshold voltage, causing U7 to output a high level, turning on Q6, keeping LED3 constantly lit, and then turning off Q2. The preset threshold voltage is changed according to the temperature of the heating device, which can be modified by a sliding rheostat.

[0039] The current detection circuit is connected in parallel across the two ends of the LED lamp LED1 under test, and includes comparator U2, comparator U9, thyristor Q7 and sliding rheostat RP3;

[0040] The positive terminal of LED1 is connected to resistor R5 and the non-inverting comparison terminal of comparator U2 via resistor R2, and the other end of R5 is grounded. The negative terminal of LED1 is connected to one end of resistor R4 and the inverting comparison terminal of U2 via resistor R3. The output terminal of U2 is connected to the other end of R4 and the non-inverting comparison terminal of comparator U9. The inverting comparison terminal of U9 is connected to the preset voltage composed of sliding rheostat RP3 and power supply. The output terminal of U9 is connected to the control terminal of Q7. The positive terminal of Q7 is connected to the source terminal of Q2. The negative terminal of Q7 is connected to the positive terminal of warning light LED3. The negative terminal of LED2 is connected to the gate of PMOS transistor Q2.

[0041] The current detection circuit collects the operating current by connecting it in parallel across the two ends of the LED lamp under test. When LED1 is short-circuited, the current is too large, causing the output voltage of U2 to exceed the preset threshold voltage. When this occurs, U9 outputs a high level to turn on Q7, which in turn turns on LED2 and turns off Q2, thus realizing the detection of excessive current.

[0042] By unifying the power input of each test circuit, unified control is achieved. When the LED under test is powered on, the test is activated simultaneously. If an abnormality is detected, the power input of the LED under test is shut off. At this time, the staff can obtain abnormal information through the warning light.

[0043] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. An LED lamp testing circuit, characterized in that, It includes a heating device, a timing circuit, a light detection circuit, a temperature detection circuit, and a current detection circuit; The light detection circuit is connected to the LED under test via an optocoupler; the temperature detection circuit is connected via a thermistor attached to the surface of the LED under test; the current detection circuit is connected in parallel across the two ends of the LED under test; the timing circuit is connected to the power supply terminal of the LED under test; and the LED under test is housed within the heating device. The LED under test, LED1, is powered by transistor Q1, and the negative terminal of LED1 is grounded.

2. The LED lamp testing circuit according to claim 1, characterized in that, The timing circuit includes a 555 timer U5, a timer U6, and a timing chip U4; The 555 timer outputs a square wave of a fixed frequency through an external connection. U6 receives the square wave output by U5 and counts it. The timing is performed by cascading. The timing chip U4 uses a 74LS85 chip and includes 4 pairs of comparison terminals. The test time is set by presetting the B0-B3 pins of the 4 pairs of comparison terminals. The output terminal of the OA=B pin of U4 is connected to the gate of the PMOS transistor Q2. The drain of Q2 is connected to the base of Q1, and the source of Q2 is connected to the power supply via button K1.

3. The LED lamp testing circuit according to claim 1, characterized in that, The light detection circuit includes a photoresistor R1, a voltage divider resistor R6, a comparator U1, a comparator U8, resistors R7 and R8, a thyristor Q8, and a sliding rheostat RP1. The photoresistor R1 and the voltage divider resistor R6 form a voltage divider network. One end of R6 is connected to the source of Q2 to obtain the power supply voltage. The voltage across R1 is sampled and amplified by comparator U1. The output of U1 is connected to the non-inverting comparator of U8. The inverting comparator of U8 is connected to a preset voltage composed of RP1 and the power supply. The output of U8 is connected to the control terminal of Q8. The positive terminal of Q8 is connected to the source of Q2. The negative terminal of Q8 is connected to the positive terminal of the warning light LED4. The negative terminal of LED4 is connected to the gate of PMOS transistor Q2.

4. The LED lamp testing circuit according to claim 1, characterized in that, The temperature detection circuit includes a temperature control resistor NTC, a voltage divider resistor R9, a comparator U3, a comparator U7, resistors R10 and R11, a thyristor Q6, and a sliding rheostat RP2. The temperature control resistor NTC and the voltage divider resistor R9 form a voltage divider network. One end of R9 is connected to the source of Q2 to obtain the power supply voltage. The voltage across the temperature control resistor NTC is sampled and amplified by comparator U3. The output of U3 is connected to the non-inverting comparator of U7. The inverting comparator of U7 is connected to the preset voltage composed of RP2 and the power supply. The output of U7 is connected to the control terminal of Q6. The positive terminal of Q6 is connected to the source of Q2. The negative terminal of Q6 is connected to the positive terminal of the warning light LED3. The negative terminal of LED3 is connected to the gate of PMOS transistor Q2.

5. The LED lamp testing circuit according to claim 1, characterized in that, The current detection circuit is connected in parallel across the two ends of the LED lamp LED1 under test, and includes comparator U2, comparator U9, thyristor Q7 and sliding rheostat RP3; The positive terminal of LED1 is connected to resistor R5 and the non-inverting comparison terminal of comparator U2 via resistor R2, and the other end of R5 is grounded. The negative terminal of LED1 is connected to one end of resistor R4 and the inverting comparison terminal of U2 via resistor R3. The output terminal of U2 is connected to the other end of R4 and the non-inverting comparison terminal of comparator U9. The inverting comparison terminal of U9 is connected to a preset voltage composed of sliding rheostat RP3 and power supply. The output terminal of U9 is connected to the control terminal of Q7. The positive terminal of Q7 is connected to the source of Q2, the negative terminal of Q7 is connected to the positive terminal of warning light LED2, and the negative terminal of LED2 is connected to the gate of PMOS transistor Q2.

Images