Not long ago, engineers designing quality control systems had to choose from several inspection options, none of which were entirely satisfactory. These options included expensive single-purpose vision systems, multi-array low-functionality photoelectric sensors, and human eye inspection, which was susceptible to fatigue and lack of concentration. However, today's state-of-the-art vision sensors combine the best performance of traditional methods with unprecedented speed, accuracy, size, and cost advantages. This article compares the capabilities of various sensing options and demonstrates why vision sensing is the fastest-growing sector in the industrial sensor market. The Basic Principles of Vision Sensing A photoelectric sensor contains a light-sensing element, while a vision sensor has thousands of pixels that capture light from an entire image. The sharpness and detail of an image are typically measured by resolution, expressed in pixels. Some vision sensors offered by Banner Engineering are capable of capturing 1.3 million pixels. Therefore, the sensor can "see" a very detailed image of a target, whether it is meters or centimeters away. After capturing the image, the vision sensor compares it to a reference image stored in memory for analysis. For example, if a vision sensor is programmed to identify a machine part with eight bolts correctly inserted, the sensor knows it should reject a part with only seven bolts, or a part with misaligned bolts. Furthermore, the vision sensor can make this judgment regardless of the machine part's location within the field of view or whether it has rotated within a 360-degree range. Advantages of Vision Sensors Among available inspection alternatives—vision systems, photoelectric sensors, manual inspection, and vision sensors—vision sensors are generally the best choice due to their accuracy, ease of use, rich functionality, and reasonable cost. As competition intensifies and profit margins shrink across industries, manufacturers cannot afford high scrap rates caused by defective products. Therefore, to detect problems before incurring high costs, manufacturers are integrating inspection into the entire manufacturing process. Comparison of Vision Systems and Vision Sensors Sophisticated vision systems are a mature technology capable of performing detailed automated inspections. However, their complexity and high cost, typically ranging from $5,000 to over $50,000, hinder their application in many industries. These complex vision systems require one or more cameras, custom software, and a computer. These systems often require external vision consultants for design, integration, and installation. Furthermore, due to their specialized nature, they cannot be easily repurposed. These complex systems typically require ongoing professional support. While the demand for complex vision systems remains, the introduction of cheaper and easier-to-use vision sensors has provided more cost-effective solutions for some industrial applications. Moreover, due to their smaller size and ease of use, manufacturers are adopting vision solutions more frequently in inspection and verification applications. Vision sensors have played a crucial role in improving quality and productivity in factory automation. Comparison of Photoelectric Sensors and Vision Sensors Compared to photoelectric sensors, vision sensors offer machine designers greater flexibility. Applications that previously required multiple photoelectric sensors can now be inspected using a single vision sensor. Vision sensors can inspect much larger areas and achieve greater flexibility in target position and orientation. This has made vision sensors widely popular in applications that were previously only possible with photoelectric sensors. Traditionally, these applications also required expensive accessories and precise motion control to ensure that the target object always appears in the same position and orientation. Furthermore, since the cost of a basic vision sensor is equivalent to only several photoelectric sensors with more expensive accessories, price is no longer an issue. Vision sensors offer unparalleled flexibility for application switching. For example, switching a production process (from single-serving yogurt to ice cream tubs) can take only seconds and can be done remotely. Additional inspection conditions can be easily added to this application. Comparison of Manual Inspection and Vision Sensors No matter how advanced factory automation becomes, many inspections are still performed by the naked eye. However, in most applications, vision sensors offer many advantages that manual inspection processes cannot match. Vision sensors can operate at much higher speeds and perform repetitive, multiple, and consistent inspections at much lower costs. Expanding Application Range The low cost and ease of use of vision sensors have attracted machine designers and process engineers to integrate them into a variety of applications that previously relied on manual labor, multiple photoelectric sensors, or no inspection at all. Industrial applications of vision sensors include inspection, metrology, measurement, orientation, defect detection, and sorting. Here are just a few application examples: ◆ In an automotive assembly plant, inspecting whether glue beads applied by a robot to the door frame are continuous and of the correct width. ◆ In bottling plants, verifying correct bottle cap seals, filling levels, and preventing foreign objects from falling into the bottle before sealing. ◆ On packaging lines, ensuring correct packaging labels are affixed in the correct positions. ◆ On pharmaceutical packaging lines, inspecting blister packs of aspirin tablets for broken or missing tablets. ◆ In metal stamping companies, inspecting stamped parts at a rate exceeding 150 tablets per minute, more than 13 times faster than manual inspection. Conclusion: This is an exciting time for vision sensors. Technology that once required extensive expertise is now economical and easy to use. Future product development using this technology will continue this trend. The challenge now is to raise awareness across industries about the potential of vision sensors in all areas of manufacturing, including quality control, measurement, and inspection processes. Machine Vision Improves Quality Control Efficiency For factory automation and process automation, machine vision is the foundation for achieving true automation and an important means of quality control. Below are some of Omron's views on the domestic machine vision market. Machine vision, as the name suggests, uses automated methods to achieve functions similar to human vision (eyes + visual nerve center + visual nerve cells). For factory automation and process automation, machine vision is the foundation for achieving true automation and an important means of quality control. In its simplest form, a machine vision system consists of a lens, camera, and controller. It replaces manual labor by measuring and judging various parameters such as size, defects, type, matching, and text based on images of objects in a specific environment. This helps customers improve production efficiency and reduce the impact of uncertainties in the field of automation, such as manual labor, on product quality. The current situation in China is somewhat unique for the entire machine vision industry chain. On the supplier side, since the vast majority are foreign manufacturers, there is a problem of understanding the domestic market and culture. Everyone has witnessed the rapid development of the domestic economy, but the factors driving this development may differ from those abroad, which is something they cannot fully understand in a short period of time. The current sales situation in China is likely still far from what most suppliers hope for. Even for a company like OMRON, which has been in the Chinese market for over two decades and has seen rapid growth in machine vision in recent years, its current sales volume is still far behind that of Japan. On the user side, the biggest problem lies in a lack of understanding of machine vision. This is partly due to the unique circumstances in China, namely the comparison between domestic labor costs and the initial investment in machine vision. Users may lack understanding of new products or problem-solving methods, or they may not be clear about the comparison between this new method and traditional manual methods. Suppliers need to do more to promote this. Integrators, the bridge between users and suppliers, also lack understanding of machine vision. They are unaware that besides mechanical and ordinary sensors, there is another method—using images/visual representations—to make judgments. There is also a severe shortage of domestic system integrators, and the proportion of self-made equipment by domestic manufacturers is too low, which is a problem that cannot be solved in the short term. Given the relatively low labor costs in China, the initial investment in machine vision is undoubtedly a factor that every potential buyer needs to consider, which also places higher demands on machine vision systems, both in terms of price and performance. Based on the above understanding, industry insiders suggest that early market cultivation, customer cultivation, and the cultivation of system integrators are crucial in the growth stage of this new product. Therefore, we have spent a lot of time on training in the fundamentals of machine vision, hoping to first enable more people to understand machine vision and its basic principles. The future of machine vision is very optimistic and we are full of confidence. We believe that with continuous self-improvement, the increasing level of automation in China, the rising demands for product quality from society, and the increasing demands for production efficiency from the manufacturing industry, machine vision, as a new product and concept, will gain widespread acceptance. Just like the stages that today's leading automation nations went through, it will achieve even greater success in a larger market. Therefore, OMRON believes that the future of machine vision is bright, although the road is long. As for the specific timeframe, it may take 5 years, or it may only take 3 years, or even less, because once domestic development begins, the speed will be astonishing. Editor: He Shiping