Global Shutter Image Sensing Technology Meets Evolving Needs of Dynamic Vision Market

The continuous evolution of current application versions and a large number of exciting emerging applications are creating a huge demand for high-performance image sensors. A good illustration of this is that image sensing devices are expected to grow at a CAGR of nearly 8% through 2020. Given the growing trend to include all types of small, portable or “mobile” products, there is an increasing demand for sensors capable of capturing sharp images in dynamic scenes in conditions ranging from very poor to extremely bright light.

The continuous evolution of current application versions and a large number of exciting emerging applications are creating a huge demand for high-performance image sensors. A good illustration of this is that image sensing devices are expected to grow at a CAGR of nearly 8% through 2020. Given the growing trend to include all types of small, portable or “mobile” products, there is an increasing demand for sensors capable of capturing sharp images in dynamic scenes in conditions ranging from very poor to extremely bright light.

Due to their operational nature, conventional designs based on rolling shutters may struggle to achieve the desired image quality. At the same time, the global shutter design is able to capture high quality images without any smearing, bending or artifacts.

The latest devices also contain functions and features that increase the utility and versatility of more image sensing applications. The global shutter image sensor market is rapidly emerging, driven by some exciting end products. Designers need high performance, with stringent operating parameters for sensors that provide small, high-function solutions that work in all lighting conditions, as well as in static and mobile environments.

With advancements in technologies such as the Internet of Things (IoT), our world has become smarter and increasingly connected. Machines also need to learn more about their surroundings. So there are billions of interconnected sensors reporting temperature, humidity, light, and various other parameters, allowing smart devices to make decisions and control things on our behalf.

While progress has been rapid and significant, traditional sensing can often only measure one parameter in a strictly defined way. As we move to the next technological revolution, image sensors are about to come to the fore, providing our world with more sophisticated sensing and recording.

The image sensing market is already huge and is expected to grow rapidly. Leading research firm Mordor Intelligence (www.mordorintelligence.com) expects the global image sensor market to reach $12.67 billion in 2018 and to grow by an average of 7.69% annually from 2014 to 2020.

As technology evolves and improves, new applications for image sensors are increasing; demand is seen even in traditional markets. Bar codes are ubiquitous, but it is not easy for image sensors in consumer or commercial applications to read barcodes more quickly and with high accuracy in sub-optimal lighting conditions. New applications such as drones, augmented reality and virtual reality (AR/VR) rely on image data to avoid collisions, capture gesture input information or precise 3D map scenes to enhance the user experience.

High-end and professional security camera technology is becoming more sophisticated and will benefit significantly from the advancements in vision technology enabled by the latest image sensors. Not only are security cameras able to work in low-light conditions, new applications are constantly being developed, and thanks to advances in technology, license plates can be read even in vehicles that are moving at high speeds.

Shutter Technology in Sensors

In CMOS image sensors, two types of shutters are available – rolling shutter and global shutter. The rolling shutter scans the image incrementally from top to bottom, exposing each row in turn.

Figure 1: Rolling shutter top-up progressive exposure sensor

While this approach mimics the mechanical shutter of most cameras, it has certain limitations (and benefits). If the camera with the sensor and the scene captured are relatively still, then there should be no problem. However, since the top-to-bottom scan takes a certain amount of time (and takes longer as more pixels are added to the sensor), if the camera or subject moves during this time, it will result in a distorted image . This is why photos of spinning airplane propellers look distorted. The advantages of rolling shutter image sensors are higher resolution, smaller pixels, and the latest pixel technology can drive higher overall image quality in a cost-effective solution.

The global shutter eliminates image smearing or warping by recording the light level captured when the entire image is consolidated and copied to storage, thereby counteracting any effects of camera movement or movement within the scene.

Figure 2: Blurred fan image with rolling shutter (left) and non-blurred version with global shutter (right)

As the need to capture undistorted images of moving objects grows (e.g. drones and AR/VR applications), global shutter means that fully representative, sharp scene capture will be possible.

Considering the mobile and battery-powered nature of many vision sensor applications, small size, light weight, and low-energy operation will be key success factors. In addition to this, there is a need to accurately capture images in poor lighting conditions, including low light levels, and extreme light and dark conditions within the same frame.

Image sensors with global shutter technology for modern applications

ON semiconductor recently introduced the AR0144, a 1/4-inch, 1.0-megapixel (Mp) (1280H x 800V) CMOS digital image sensor that captures sharp, accurate images in both bright and low-light conditions. Artifacts do not appear. The 3.0um pixel sensor uses a global shutter to meet the stringent requirements for accurate and fast image capture in both static and mobile scene applications. Its high shutter efficiency and signal-to-noise ratio substantially reduce ghosting and noise effects, improving overall image quality.

In static applications such as barcode scanners, the AR0144 guarantees fast results by ensuring the first scan. In battery powered dynamic applications such as drones, the sensor’s low energy consumption (

The AR0144 offers a high degree of flexibility with the choice of main image/video, trigger frame/single frame, and auto-trigger operation modes. Exposure time is controlled via a 2-wire serial interface, and column selection size and blanking time configuration allow resolution and frame rate (up to 60fps at full resolution) to be adjusted to cover any region of interest (ROI) required by the application.

The sensor is available in monochrome and color versions. The sensor is 50% smaller than previous generations due to reduced pixel size. Available in 5.6 mm x 5.6 mm chip size or die format, ultra-small solutions can be easily embedded in space-constrained handheld or portable devices.

Summarize

As sensing moves to fully vision-based systems that enable connected devices to truly “see” and interpret their environment, global shutter technology represents a major step forward in producing high-quality images, even under challenging conditions The same is true below.

The market will never stand still, and the demand for higher resolution sensors will continue to grow to address more details. One example of continued innovation in this area is ON Semiconductor, which is developing more advanced and fully functional global shutter sensors.

The Links:   AT655S22 MDF250A20M