Under the trends of "Industry 4.0" and "Made in China 2025," industrial automation continues to strengthen, and machine vision has become an important emerging field in the electronics industry. Driven by sustained demand for automation, social security, and market economic strength, the global machine vision and intelligent transportation systems market is experiencing a boom. In China, an increasing number of large manufacturers are entering the machine vision market.
Performance Indicators and Development Trends of Image Sensors
Image sensors are key components in machine vision systems for capturing image information. Factors that measure image sensor performance include resolution, sensitivity, bandwidth, noise, power consumption, optical format, frame rate, and CRA (Current Dynamic Range). No single image sensing technology or product is suitable for all applications; therefore, designers must match the most suitable technology to the application requirements. Relatively speaking, CCD sensors offer the best image uniformity, high linear dynamic range, high light sensitivity, and large optical format, while CMOS sensors offer flexible readout, low power consumption, high frame rate, and high integration capabilities. In terms of application markets, FullFrame CCDs are targeted at scientific and medical fields, InterlineTransfer CCDs and global shutter CMOS are used in machine vision and intelligent transportation systems, linear CCDs are suitable for scanning, food/beverage applications, and rolling shutter CMOS is mainly used in the security monitoring industry. Both CCD and CMOS image sensors are trending towards smaller pixels (while maintaining performance), larger optical formats, and improved output designs and processes to meet market demands for higher resolution, faster output speeds, enhanced quantum efficiency (QE), reduced noise, and lower costs. High-speed image capture provides high throughput, high-quality images enable accurate analysis, and high-resolution captures clear image details.
ON Semiconductor is the only supplier capable of providing both CMOS and CCD image sensors.
ON Semiconductor, with over 40 years of imaging expertise and the technological advantages of its acquisitions of Cypress, Truese, and Aptina, is the only supplier capable of providing both CMOS and CCD image sensors. In 2015, it held the largest market share in both the security and scanning image sensor markets, and ranked second in the machine vision market. The company boasts unparalleled product technology and a comprehensive product portfolio. Its broad technological foundation includes CCD and CMOS pixel design, back-illuminated sensors, electron multiplication, system-on-chip (SoC) integration, dedicated color filter arrays (CFAs), high-speed readout architectures, proprietary coprocessors, and custom design capabilities. Pixel sizes range from 1.1µm to 24µm, resolutions from VGA to over 50 megapixels, and optical formats from 2.2mm to over 70mm. ON Semiconductor also invests heavily in and develops future leading technologies to keep pace with market developments. This article will focus on ON Semiconductor's PYTHON series of global shutter CMOS image sensors and its InterlineTransfer CCD image sensor.
Global shutter CMOS image sensor
CMOS image sensors offer features not found in CCD image sensors, integrating digital processing capabilities such as converting electrical charge into voltage within pixels, thus providing faster frame rates than CCDs. Furthermore, the CMOS architecture allows users to design small window outputs to meet their needs, making readout more flexible. In addition, CMOS boasts low power consumption and simple design. While CCD image sensors still lead in image quality, the difference in image quality between global shutter CMOS and CCD image sensors will become increasingly smaller with technological advancements. Key applications of global shutter CMOS image sensors include inspection, medical imaging, motion analysis, security, microscopy, and intelligent transportation, among others.
PYTHON Global Shutter CMOS Sensor for High-End Industrial Applications
ON Semiconductor's PYTHON series offers superior image quality, high and flexible readout speeds, low-power/frame-rate versions, and scalable platforms to meet the demanding needs of industrial imaging and intelligent transportation applications, such as inspection systems, license plate recognition, surveillance, scientific research, traffic cameras, robot guidance, and motion analysis.
1. Superior image quality
PYTHON employs a patented global shutter structure to ensure motion artifact-free capture of moving objects, intra-pixel correlated double sampling (CDS) ensures low output noise, on-chip fixed pattern noise (FPN) correction provides enhanced image quality, image quality is optimized for specific end applications based on application configurability, and high quantum efficiency provides excellent sensitivity from ultraviolet to near-infrared. Products are available in monochrome, color, and near-infrared.
2. Low power/frame rate versions are available.
To meet the needs of some customers who want to reduce product power consumption and cost, ON Semiconductor also offers the low-power PYTHON1300 and PYTHON5000, which optimize power consumption by about 33% by reducing the frame rate, while retaining the high optical performance of the PYTHON series, making them a cost-effective choice for applications that can support low frame rates.
3. High and flexible read speed
PYTHON boasts bandwidth that meets and surpasses modern interfaces such as USB3, USB3.1, 10GigE, and Cameralink. ROI mode allows for customized output selection, and speed increases quadratically when the window is open.
Figure 1: PYTHON's high bandwidth supports high frame rates and high resolutions.
4. Scalable
The PYTHON series comprises nine different devices, offering resolutions from VGA to over 25 megapixels, in three package sizes. All devices share similar electrical and design requirements, and all products can share the same design.
Figure 2: Nine devices in the PYTHON series
Therefore, based on PYTHON's support for high bandwidth above USB3, it can provide faster frame rates without sacrificing image quality. The resolution of up to 25 megapixels meets the market trend of demanding higher resolutions. Nine different resolution options can provide customized solutions for end customers according to different application needs. Scalability shortens design time and accelerates product launch.
The general platform block diagram of PYTHON is shown in Figure 3. Typically, an FPGA is used to provide external control signals for the sensor and to serve as the output conversion interface for the sensor. It also performs some simple image processing and outputs images using video interfaces such as USB 3.0, GigE, and CameraLink.
Figure 3: PYTHON General Platform Block Diagram
InterlineTransfer CCD Image Sensor
InterlineTransfer CCD offers more functionality than Fullframe CCD. It uses an electronic shutter, which is simpler and more stable than a mechanical shutter, resulting in better image consistency and lower noise. It can be used in fields with extremely stringent image quality requirements, such as machine vision, surveillance, intelligent transportation, medical, and scientific fields.
ON Semiconductor's InterlineTransfer CCDs are currently most commonly used in two series: 5.5μm and 7.4μm, with resolutions ranging from 1 million to 29 million pixels and optical formats from 1/2” to 35mm. They feature advanced imaging performance such as low noise and low smear, and a global shutter architecture. They offer monochrome, Bayer color, and sparse color filter array configurations. All devices in the series share common output pins, packages, and timing definitions, requiring only a dedicated ID pin for differentiation. This allows a single camera design to be used in over 30 products across the entire series, simplifying design. The 5.5μm series is used for mainstream applications, while the 7.4μm series is used for enhanced imaging performance.
1. World's highest resolution Interline Transfer CCD: KAI-47051
The KAI-47051 image sensor offers excellent image uniformity and a global shutter architecture for demanding imaging applications such as flat panel inspection and aerial reconnaissance. Its 47-megapixel resolution captures very sharp image details, and its 16-channel output architecture supports frame rates up to 7fps. It also features monochrome, Bayer color, and SparseCFA configurations.
Compared to CMOS design, CCD has stricter power and clock requirements, requiring dedicated horizontal clock drive, vertical clock drive, and electronic shutter drive. Since it outputs analog signals, an external ADC is needed to convert the analog signals into digital signals, which are then processed by an FPGA and output as images via video interfaces such as USB 3.0, GigE, and CameraLink.
Figure 4: Block diagram of KAI-47051 platform
2. KAI-29050 and KAI-08052 image sensors
The KAI-29050 and KAI-08052 are 5.5-micron InterlineTransfer CCD image sensors offering excellent image uniformity and a global shutter architecture, as well as monochrome, Bayer, and Sparse CFA configurations, and four outputs for flat panel inspection and aerial reconnaissance. These two devices have 28.8 million and 8.1 million pixels, respectively, and support frame rates of 4fps and 16fps. The KAI-08052, in particular, features enhanced near-infrared sensitivity, which is crucial for advancing scientific research and medical applications.
Other CMOS image sensors
1. Global shutter CMOS sensor AR0135
As an upgrade to the AR0134, the AR0135 features a 3.75-micron pixel size, a resolution of up to 1 million pixels, an optical size of only 1/3 inch, supports 720p at 60fps, has low power consumption, a compact package, and low read noise, making it suitable for barcode scanning, industrial applications, toys/game consoles, automotive, and other fields.
2. Global shutter CMOS sensor AR0144
The AR0144 boasts a pixel size of only 3 micrometers, making it the industry's smallest global shutter CMOS sensor. It features a 1-megapixel resolution, an optical size of only 1/4 inch, low noise, extremely low dark current at high temperatures, support for 60fps, and a very compact package. Its target markets include barcode scanning, toys/game consoles, and industrial applications.
Summarize
As the only supplier with both CCD and CMOS technologies, ON Semiconductor boasts over 2,000 technology patents and a broad product portfolio ranging from rolling shutters to global shutters, from VGA to 47-megapixel sensors, and from low-speed, low-power to high-frame-rate displays. Adapting to the evolving trends in machine vision and industrial applications, ON Semiconductor meets diverse customer needs. Coupled with an experienced local technical team in China, strong sales support, and a dedicated image engineering solutions center in the Asia-Pacific region, ON Semiconductor helps Chinese manufacturers win in the market.
