Device for testing light emitting diode on printed circuit board assembly

Abstract

The utility model provides a testing device for detecting the state of a light emitting diode on a printed circuit board assembly. The device comprises a shade part, the shade part is provided with a through hole corresponding to the position of a light emitting diode on a circuit board, and the circuit board is arranged on the first side of the shade part. The detection circuit is installed on the second side of the shade part and comprises photosensitive diodes with the same number as the light-emitting diodes, and each photosensitive diode corresponds to one through hole so as to ensure that the light can only irradiate the corresponding photosensitive diode. All the photosensitive diodes are connected in series and lead out anodes and cathodes so as to be connected to a measuring instrument, thereby realizing accurate detection of on-off states of the light-emitting diodes. Through the device, the on-off state of the light emitting diode can be accurately detected, and the detection efficiency and reliability are effectively improved.

Description

Technical Field

[0001] The present invention relates to the field of electronic testing technology, and in particular to a method for detecting printed circuit board components.

[0002] A device for detecting the working status of a light emitting diode (LED) on a printed circuit board assembly (PCBA). Background Art

[0003] Light-emitting diode (LED) indicators on printed circuit board assemblies (PCBAs) are electronic components installed via surface-mount or plug-in methods. They are widely used in various electronic devices to display device icons, operating status, power status, signal transmission status, and more. As electronic product functionality becomes increasingly diverse and complex, the number of LEDs integrated on PCBAs continues to increase. Ensuring that each LED is properly illuminated has become an essential testing step in the production process.

[0004] Currently, the primary methods for inspecting the on / off status of LEDs on PCBAs are manual visual inspection and optical inspection equipment. Manual visual inspection relies on operators visually observing the on / off status of each LED individually, resulting in low efficiency, poor reliability, and high health risks. As the number of LEDs increases, individual inspections become time-consuming, impacting production efficiency. Operators are also susceptible to fatigue and external factors, potentially leading to missed inspections or misjudgments. Furthermore, staring at high-brightness LEDs for extended periods can cause visual fatigue and even damage.

[0005] Optical inspection equipment can improve automation and accuracy, but it's expensive and increases production costs, making it unsuitable for low-margin orders. Furthermore, this method requires custom fixtures and equipment, increasing design and manufacturing complexity. Equipment adjustments and replacements are also time-consuming, making it difficult to adapt to the demands of high-variety, low-volume production.

[0006] In summary, existing LED on / off detection methods are either inefficient and unreliable, or costly and inflexible, making them unable to meet the demands of fast, efficient, and cost-effective production of modern electronic products. Therefore, a simple, low-cost, and highly reliable LED on / off detection device is urgently needed to improve production efficiency, reduce costs, and protect the health of operators. Summary of the Invention

[0007] The present invention provides a device for testing the on / off status of a light emitting diode (LED) on a printed circuit board assembly, aiming to solve the problems in the prior art of relying on manual visual inspection, which leads to low efficiency, personnel fatigue and possible vision damage.

[0008] The device includes:

[0009] 1. A mask shaped to match a printed circuit board assembly to be tested, the mask having apertures corresponding to the positions of each light emitting diode on the printed circuit board assembly. The mask is made of a light-tight material, which effectively shields the light from the outside and ensures the accuracy of the test. Meanwhile, the printed circuit board assembly is arranged on a first side of the mask, and the mask is configured to hold the printed circuit board assembly so that the light emitting diodes are accurately aligned with the apertures, ensuring that the light can accurately irradiate the photodiodes on the other side.

[0010] 2. A detection circuit mounted on a second side of the mask opposite the first side, comprising at least one photodiode. The number of photodiodes is the same as the number of light emitting diodes to be tested, and the arrangement of the photodiodes on the detection circuit corresponds to the distribution of the light emitting diodes on the printed circuit board assembly, so that each photodiode is aligned with an aperture. The photodiodes are of a type whose reverse voltage drop decreases with increasing light intensity, and their sensitivity is suitable for detecting the light emitted by the light emitting diodes.

[0011] 3. A connection mode in which all the photodiodes are connected in series and have positive and negative terminals for connection to a measuring instrument. The positive terminals of the photodiodes are connected to the negative input terminals of the measuring instrument, and the negative terminals are connected to the positive input terminals of the measuring instrument. The measuring instrument is preferably a multimeter set to the diode range, or an instrument with data storage and reading functions can also be used to facilitate the traceability of production quality.

[0012] When the light emitting diodes on the printed circuit board assembly are lit, the corresponding photodiodes are illuminated, and their reverse voltage drops decrease. Since all the photodiodes are connected in series, the measuring instrument will only show a specific voltage drop value when all the light emitting diodes are lit normally. If any of the light emitting diodes is not lit, the reverse voltage drop of the corresponding photodiode cannot decrease, resulting in an undetectable voltage drop in the entire series circuit, and the measuring instrument will show an out-of-range or no reading.

[0013] With this device, the tester does not need to visually check the on-off state of each light emitting diode one by one, but only needs to observe the reading of the measuring instrument to quickly determine the status, which is simple and efficient. The design of the mask makes the device applicable to printed circuit board assemblies of different shapes and sizes, and only the positions and number of apertures need to be adjusted. The sensitivity of the photodiodes ensures accurate and reliable detection of the light emitted by the light emitting diodes.

[0014] The device of the present application has a simple structure and low cost, does not require complex optical detection equipment, and is suitable for production orders of various scales. The use of a black, light-tight mask material effectively avoids interference from external light, improving the accuracy of the test. By fixedly mounting the detection circuit, the accurate alignment between the photodiodes, apertures and light emitting diodes is ensured, enhancing the stability and reliability of the device.

[0015] The present invention not only improves the efficiency of detecting the on-off status of light-emitting diodes and reduces the labor intensity of detection personnel, but also avoids visual fatigue and vision damage caused by long-term visual observation of high-brightness light sources, and has significant practical value and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The circuit principle of the device of the present invention is demonstrated.

[0017] Figure 2 Schematic diagram of the overall structure of the device of the present invention.

[0018] Figure 3 Schematic diagram of the overall structure of the device of the present invention. DETAILED DESCRIPTION

[0019] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the present invention is not limited to the following specific embodiments, and those skilled in the art may make various changes and improvements based on the contents of the present invention, as long as they do not exceed the essential contents of the present invention, they are all within the scope of protection of the present invention.

[0020] Example 1

[0021] The present invention is based on the reverse voltage drop characteristics of the photodiode 200 and combined with the mask portion 100 to realize the detection of the on and off state of the light emitting diode LED410 on the printed circuit board assembly PCBA. Figure 1 The circuit schematic is shown.

[0022] The mask 100 is made of opaque material. Its primary function is to block external light interference, allowing light from LEDs 410 on the PCBA 400 on one side of the mask 100 (as indicated by the arrows in the figure) to reach the photodiodes 200 on the other side only through through-holes 101 in the mask 100. The mask 100 can be mounted on the PCBA 400, with the positions of the through-holes 101 corresponding to the positions of each LED 410 on the PCBA 400. This design ensures that light from each LED 410 only reaches its corresponding photodiode, enabling independent and precise detection of each LED 410.

[0023] The number of photodiodes 200 is equal to the number of LEDs 410 on the PCBA 400. These photodiodes are connected in series to form a detection circuit 300, and the positive and negative poles are brought out for connection to the measuring instrument 500. During the detection process, when all LEDs 410 on the PCBA 400 are normally lit, each photodiode will be illuminated, and its reverse voltage drop will decrease, thereby making the entire series circuit conductive. At this time, the measuring instrument 500 (for example, a multimeter set to the diode position) displays the conductive state, thereby confirming that all LEDs 410 are in normal working condition. If any LED 410 is not lit, the reverse voltage drop of its corresponding photodiode remains high, blocking the flow of current in the entire series circuit. At this time, the measuring instrument displays "out of range" or "no reading" (i.e., OL state), indicating that there is an unlit LED 410.

[0024] The design of the mask portion 100 effectively prevents interference with detection from external light sources while also ensuring that the photodiodes 200 can accurately detect the on / off status of their corresponding LEDs 410. Furthermore, when the multimeter is set to the diode position, it can accurately determine the conduction state of the circuit, thereby simplifying the detection process, improving detection efficiency and reliability, and reducing visual stress on the operator.

[0025] Example 2

[0026] The difference between this embodiment and the first embodiment is that it focuses more on the specific implementation method of the structure.

[0027] Please refer to Figure 2 and Figure 3 As shown in the structural diagram, the device of the present invention includes a mask 100 for detecting the on / off status of LEDs 410 on a PCBA 400, a detection circuit 300 (composed of a PCB and a photodiode 200), a measuring instrument 500 (such as a multimeter), and its connecting components. The mask 100 is made of an opaque material (such as acrylic or black ABS plastic) to effectively shield external light sources and improve detection accuracy. The mask's shape matches the shape of the PCBA 400 to be tested. The mask is designed with at least one through-hole 101, each measuring 6 mm in length and width (or a circular through-hole with a diameter of 6 mm), corresponding to each LED 410 on the PCBA 400. This design ensures that light from each LED 410 can only pass through its corresponding through-hole 101 and illuminate the designated photodiode 200 below. This ensures that the light source of each LED 410 is precisely aligned with the corresponding photodiode, preventing interference with the detection of other photodiodes.

[0028] The detection circuit 300 is composed of a PCB board and the photosensitive diodes 200 welded thereon. The number of photosensitive diodes on the PCB board is the same as the number of LEDs 410 on the PCBA 400 board to be detected, so as to realize one-to-one correspondence detection. In the embodiment, it is assumed that there are 10 LEDs 410 on the PCBA 400 board to be detected, and 12 photosensitive diodes of BPW34 type are installed on the PCB board. The positions of the photosensitive diodes correspond to the design of the through holes 101 of the mask part accurately. All the photosensitive diodes are connected in series and the positive and negative electrodes are led out for connection to the measuring instrument 500. The connection in series ensures that, during the detection process, all the photosensitive diodes in the series circuit can be turned on only when all the LEDs 410 are lit, so that a certain voltage drop value of the whole circuit is generated for the measuring instrument to read.

[0029] On the PCBA 400 board, the connection mode of the LEDs 410 can be designed as series or parallel according to requirements. In the embodiment, it is assumed that the LEDs 410 are connected in parallel to ensure that even if a certain LED 410 fails, the other LEDs 410 can still work normally. The parallel connection mode can also simplify the circuit design and facilitate flexible configuration in actual application.

[0030] The measuring instrument 500 selects a digital multimeter (such as Fluke 17B+ type) with a diode detection range. The multimeter has high sensitivity and accuracy and is suitable for detecting small current and voltage changes. During the detection process, the multimeter is set at the diode range to measure the voltage drop of the whole series circuit. The positive electrode 301 of the series photosensitive diodes 200 on the PCB board is connected to the black test probe interface of the multimeter through a wire, and the negative electrode 302 is connected to the red test probe interface. The multimeter is kept connected with the PCBA 400 board and the detection circuit 300 to ensure that the current and voltage changes during the detection process can be accurately conducted to the measuring instrument 500.

[0031] In the specific detection process, the PCBA 400 board to be detected is placed on the mask part 100 to ensure that each LED 410 corresponds to a through hole 101 of the mask part 100. Then, the PCBA 400 board is powered by an external power supply to make all the LEDs 410 light up. Due to the design of the through holes of the mask part 100, the light of the LEDs 410 can only irradiate the corresponding photosensitive diodes 200. When all the LEDs 410 are lit, the photosensitive diodes 200 are irradiated, their reverse voltage drop is reduced, the whole series circuit is turned on, and the multimeter will display the on state, indicating that all the LEDs 410 work normally. If any LED 410 is not lit, the corresponding photosensitive diode 200 cannot be irradiated, its reverse voltage drop remains high, thereby blocking the current flow of the whole series circuit, and the multimeter will display the "OL" state, indicating that there is an unlit LED 410.

[0032] Through the structural design and testing process of the mask 100 and detection circuit 300, the present invention provides a simple and reliable method for detecting LED 410 on a PCBA 400. The black, opaque material of the mask 100 effectively prevents interference from external light sources. The series-connected photodiode circuit ensures detection accuracy, and the multimeter 400 allows operators to quickly identify the on / off status of LED 410 on the PCBA.

[0033] Compared with the existing technical methods for detecting the on / off status of light-emitting diodes on printed circuit board assemblies, the present invention has significant improvements and advantages, as follows:

[0034] 1. Improve detection efficiency and reliability

[0035] Traditional manual visual inspection relies on operators observing the on / off status of LEDs one by one, which is inefficient and unreliable. This is especially time-consuming and carries a high risk of misjudgments and missed detections on PCBAs with a large number of LEDs. In contrast, the test device of the present invention, through the precise alignment of the mask and photodiode, allows inspectors to confirm the on / off status of all LEDs simply by observing the readings of the measuring instrument. This simplified operation significantly improves inspection efficiency and effectively reduces the rate of misjudgments and missed detections.

[0036] 2. Simplify testing equipment and reduce costs

[0037] While optical inspection equipment is accurate in automated testing, it is expensive and typically requires specialized equipment and fixtures, making it difficult to adapt to the production needs of high-variety, small-batch production, limiting its application in cost-sensitive orders. The device of the present invention utilizes a detection solution combining a photodiode and a multimeter in series. It features a simple structure, low cost, and eliminates the need for complex optical equipment, making it suitable for production environments of all sizes.

[0038] 3. Reduce visual fatigue and protect the health of operators

[0039] During manual visual inspections, operators need to stare at high-brightness LED light sources for extended periods, which can easily cause visual fatigue and even damage. The mask design and measuring instrument of the present invention eliminate the need for inspectors to directly view the high-brightness LED light source, reducing the strain of prolonged visual observation and effectively protecting the operator's vision.

[0040] 4. Precise optical isolation design to ensure detection accuracy

[0041] The mask portion of the present invention is made of opaque material, which can effectively shield external light interference, so that the LED light signal is only irradiated onto the designated photodiode through the corresponding through hole, avoiding interference from other light sources and ensuring the accuracy and stability of the detection results.

[0042] 5. Flexible adaptation to various PCBA specifications, strong adaptability

[0043] The mask design allows for flexible adjustment to different PCBA board shapes and LED distributions, adapting to the inspection requirements of PCBAs of varying specifications. Precise alignment of the through-holes and photodiodes ensures the individual detection of LED light signals, while also improving the device's adaptability and detection accuracy, facilitating rapid adjustments on production lines.

[0044] In summary, the present invention effectively solves the problems of low detection efficiency, high cost, and complex operation in the existing technology, realizes the automation, efficiency and cost reduction of LED on and off status detection, and provides a better detection solution for the mass production of modern electronic products.

[0045] Although the present invention has been described in conjunction with specific embodiments, it will be understood by those skilled in the art that these embodiments are merely illustrative and should not be construed as limiting the present invention. The scope of the present invention should be determined by the claims, not the specific details of the embodiments.

Claims

1. A device for testing light emitting diodes on a printed circuit board assembly, characterized in that: include: a mask portion, wherein the mask portion is provided with through holes corresponding to positions of light-emitting diodes on the printed circuit board assembly, and the printed circuit board assembly is arranged on a first side of the mask portion; a detection circuit mounted on a second side of the mask portion opposite to the first side, the detection circuit comprising at least one photosensitive diode; the number of the photosensitive diodes is the same as the number of the light-emitting diodes, and each photosensitive diode corresponds to one through hole; All photodiodes are connected in series, and the positive and negative poles are brought out for connection to measuring instruments.

2. The device for testing light emitting diodes on a printed circuit board assembly according to claim 1, wherein: The mask portion is made of light-proof material.

3. The device for testing light emitting diodes on a printed circuit board assembly according to claim 1, wherein: The photosensitive diode is a photosensitive diode whose reverse voltage drop decreases as the light intensity increases.

4. The device for testing light emitting diodes on a printed circuit board assembly according to claim 2, wherein: The anode of the photodiode is connected to the cathode input terminal of the measuring instrument, and the cathode is connected to the anode input terminal of the measuring instrument.

5. The device for testing light emitting diodes on a printed circuit board assembly according to claim 4, wherein: The measuring instrument is a multimeter set at the diode position.

6. The device for testing light emitting diodes on a printed circuit board assembly according to claim 1, wherein: The detection circuit is fixedly mounted on the lower surface of the mask portion.

7. The device for testing light emitting diodes on a printed circuit board assembly according to claim 1, wherein: The arrangement of the photosensitive diodes on the detection circuit corresponds to the distribution of the light emitting diodes on the printed circuit board assembly.

8. The device for testing light emitting diodes on a printed circuit board assembly according to claim 7, wherein: The mask portion is configured to support the printed circuit board assembly so that the light emitting diodes are aligned with the through holes.

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