FLAT PANEL DISPLAY INSPECTION: CAMERA DEVELOPMENTS TARGET EVOLVING TECHNOLOGY AND GROWING PRODUCTION VOLUMES
Flat panel displays (FPD) are common in every aspect of our lives today — from televisions to computers to mobile phones, in-car displays, and smart watches, they truly are everywhere. Along with their proliferation, flat panel displays have also grown in size and resolution. In many instances, ultra-high definition (4K and 8K) has become the norm. While these advancements provide multiple benefits to the user, they also bring with them new challenges when it comes to both flat panel display manufacturing and inspection. Pixels continue to shrink in size as do the defects, resulting in the need for higher resolution and more sophisticated imaging technologies to keep pace with quality control demands and expectations.
FLAT PANEL DISPLAY INSPECTION CHALLENGES
Camera resolution is only part of the equation, however. Increasing global demand for LED and OLED displays means that production rates remain high, while also requiring that inspection times be as short as possible to avoid slowing productivity. With the pixel densities of modern displays being what they are, the result is that today’s highest resolution and highest speed sensors must be paired with an equivalent technology capable of transmitting image data to processing nodes in real-time. Advanced Ethernet interfaces that operate at 25GigE and above are ideally suited to this task as they can handle the sensor data rates and meet the data delivery requirements, all while utilizing simplified cabling and readily available hardware solutions.
Fig 1: High-resolution GigE Vision cameras from Emergent can be reliably deployed for flat panel display inspection of smartphones during assembly.
The FPD manufacturing process is complex and involves the layering of several different materials and components including glass, electronics, films, and coatings. Because of the precision involved in the process and the growing competition among brands, manufacturers are increasingly seeking to inspect every flat panel display to identify flaws and prevent defective units from making it into the hands of consumers.
HIGH-SPEED, HIGH-RESOLUTION CAMERAS FOR INSPECTING FLAT PANEL DISPLAYS
The inspection process can easily become a bottleneck in FPD manufacturing, particularly when considering the combination of increased manufacturing speeds and quantities with the goal of achieving 100% inspection. Speeding up manufacturing rates and processes only succeeds if the display inspection and quality control process can keep up. As a result, cameras that are not only high-speed but also high-resolution and with high sensitivity are necessary to reduce image acquisition times while capturing images capable of identifying flaws in the finished product.
Fig 2: Based on the 127.7MP Sony IMX661 CMOS sensor, the Bolt HB-127-S 25GigE camera reaches 17fps for high resolution, high speed flat panel display application requirements.
Emergent Vision Technologies has dedicated its camera development efforts to producing some of the fastest and highest resolution machine vision cameras in the industry. Well suited to a variety of inspection tasks, flat panel display inspection stands out as an application that can truly benefit from these offerings. But, as previously mentioned, high-speed image acquisition is only part of the solution. Imaging devices must also be able to transmit those images in real-time to computers for processing. Fortunately, Emergent has eliminated those bottlenecks as well by pairing their cameras with high-speed Ethernet interfaces capable of achieving throughputs of up to 100Gbps.
ZERO-DATA-LOSS GIGE VISION CAMERAS
Unlike some products that rely on proprietary, purpose-built, or point-to-point interfaces and acquisition boards, Emergent leverages GigE Vision and readily available Ethernet infrastructure to achieve robust and reliable data acquisition and transfer with best-in-class performance. Utilizing an optimized GigE Vision implementation and with support for direct transfer technologies such as NVIDIA’s GPUDirect, the technology mitigates the impact of large data transfers on the system CPU and memory, and instead, utilizes more powerful GPU capability for data processing. This is done while maintaining compatibility with the GigE Vision standard and interoperability with compliant software and peripherals.
Further simplifying the design and development of machine vision inspection systems for flat panel display inspection, Emergent’s cameras benefit from single-cable-connectivity. Unlike some interface choices that rely on two or more cables to achieve the necessary data throughput, GigE Vision devices can transmit their entire bandwidth over a single cable. This means cost savings and reduced complexity for those building systems, fewer failure points and connections, and the ability to route cabling through smaller, narrower spaces and conduit. In applications where multiple cameras are needed, the benefits are compounded.
With a broad range of flat panel displays being manufactured for the marketplace today, inspection systems can vary in complexity, size, and configuration. Where displays are small in physical size, area scan cameras may offer a simplified approach to system design while still ensuring the ability to identify flaws reliably. For larger displays, area scan may not be as practical; in those situations, line scan cameras provide high-speed continuous imaging of the FPD as it moves through the camera’s field of view. In all cases, the goal is to provide complete inspection of the display. Emergent’s offerings include both area-scan and line scan solutions that can meet the demands of FPD manufacturing today and into the future.
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