ICs & Semiconductors

Solving the challenges of implementing vision systems

By Danny Scheffer, product line manager, Industrial and Commercial Solutions Division, ON Semiconductor


he use of image sensors in industrial applications including factories, traffic systems, scientific/ medical, retail, surveillance and robotics is growing significantly as organisations seek to introduce greater control into their processes to improve quality and control costs.

In factories, image sensors are improving in-process and end-of-line inspection as well as worker safety by equipping robots with vision. In the scientific and medical world image sensors are an essential element in digital radiography and distributed diagnostics where it is used for x-ray crystallography, DNA profiling, astrophotography and more. Security is a perennial concern in many aspects of our modern life. Image sensors with higher resolution and image quality are being used in drones/ UAVs for border security. Our roads are becoming safer and more secure as image sensors are used to monitor intersections and detect road traffic violations, and identifying vehicles through automatic number plate recognition (ANPR).

the all-important low light performance of the image sensor.

One key parameter that defines the quality of a video feed is the

number of frames-per-second (fps) that a sensor can deliver. Coupling this with increased resolution means that more pixel data is contained in every frame which requires a significant speed increase in the sensor architecture to deliver smooth video feeds that are free from ‘jerkiness’. Many modern cameras have dispensed with mechanical shutters as they can be bulky and prone to failure after long periods of use. Modern cameras increasingly use an electronic shutter where all of the pixels are captured simultaneously – a technique known as ‘global shutter’.

As sensors are increasingly used in applications where motion is a factor (either the sensor is on a moving vehicle or the scene to be captured contains moving items), modern sensors that incorporate a fast global shutter are needed to avoid the image ‘smearing’ and other undesirable artefacts associated with ‘rolling shutter’ technology.

Challenges for designers

Figure 1: Image sensors are used in a wide variety of industrial applications

As the demands of users are increasing, the power and quality of these image sensors is also advancing rapidly to enhance performance in existing applications as well as enabling new uses for these devices.

Key technology drivers

A number of technology advances in image sensing are driving these performance enhancements. Backside illumination (BSI) re-arranges the key imaging elements of the sensor by flipping the silicon wafer, moving the photocathode layer in front of the wiring, thereby significantly improving

20 July/August 2021

There are many factors to be considered when designing a camera for modern applications, many of which relate to the choice of image sensor – a critical decision that can make or break a design.

A high-resolution image sensor is needed in almost all applications, like medical applications where the camera is expected to detect the early signs of disease or factory inspection applications where the smallest defect must be found. However, as resolution is added, there are implications for the rest of the design, requiring greater bandwidth for data transfer, more processing power and increased memory capacity for storage. It is therefore essential that the sensor specified is adequate for the task, but not over-specified as this will increase cost in almost all aspects of the design.

Components in Electronics

As image sensors are being incorporated into mobile applications such as drones/ UAVs and automatically guided vehicles (AGVs) which are invariably battery-powered, the power consumption of the camera solution – including the image sensor – is now a

significant consideration. While the image sensor is an essential feature, the current that it draws will deplete the batteries, reducing the time between charges for the vehicle. In many cases, cameras perform multiple tasks that require different resolutions like low resolution cameras are used for simple detection and higher resolution cameras are used where detection of details is required. However, as this requires using different sensors for each resolution, in many cases a different design is required for each sensor, thereby increasing the design task (and time) significantly. Even when the designs are complete, as each is different, then the ability to take advantage of economies-of-scale is significantly diminished.

With many companies implementing image sensors for the first time to add valuable features to their products, the learning curve can be incredibly steep. Some manufacturers offer comprehensive tools to reduce design risk and guide designers through the design process. In many cases, these tools are also valuable to experienced designers that need to get to proof-of-concept in accelerated timescales and then have a seamless path to a series production version.

Design support

With their XGS image sensors, ON Semiconductor has taken a ‘family’ approach to the series. There is a total of seven devices offering resolutions from 2.3MP to 16MP, all with a common footprint that is compatible with the industry-standard 29mm x 29mm layout. Likewise, the four devices that cover the range 20Mp to 45Mp also share a common footprint.

The great benefit of this approach for designers is that they can have a single camera hardware design with known performance for each resolution range and IP

such as firmware can be re-used throughout the series of cameras. This dramatically reduces design time and risk and allows access to economies-of-scale in manufacture.

Figure 2: The XGS series offers excellent perfor- mance and significant design support

Within each image sensor, an advanced 3.2 μm pixel design delivers excellent image quality with low levels of noise, even in low-light conditions. A rapid global shutter allows the capture of high-quality images without the artefacts associated with rolling shutter technology. Various speed grades are available, making efficient use of available interface bandwidth, thereby allowing designers to manage system cost. Despite their high performance, XGS devices with resolutions up to 45 Mp all consume less than 1000 mW even when operating at full speed.

Figure 3: The XGS series of CMOS Image Sensors with Resolutions up to 45 Mp

Image sensing is growing rapidly in many application sectors including industrial as it allows systems to recognise and interact with the world around them. As a result, in order to offer state-of-the-art solutions many companies are now offering vision capability for the first time. This can present a very steep learning curve for designers, especially when a dedicated design is required for each sensor resolution. With their low-power, low noise XGS series of high-performance image sensors that share a common footprint and the availability of multiple easy-to-use development platforms, ON Semiconductor allows designers a fully supported path to rapid state-of-the-art camera design.

Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58