Image sensor Isocell image sensing

technology…

SHOAIB MALIKROLLNO.10471SYIT

ABOUT IMAGE SENSOR CMOS AND SAMSUNG’S ISOCELL IMAGE SENSOR TECHNOLOY

CONTENT▪ Sensor▪ How to choose a sensor?▪ What is an Image Sensor?▪ What is a Pixel?▪ What is Fill Factor?▪ CMOS ▪ ISOCELL Image Sensor

ISOCELL CMOS SENSOR

WHAT IS A SENSOR?

▪ A sensor is a device that measures a physical quantity and converts it into a signal which can be read by an observer or by an instrument. ▪ For example, a thermocouple converts temperature to

an output voltage which can be read by a voltmeter.▪ For accuracy, all sensors need to be calibrated against

known standards.

Physical phenomenon

Measurement Output

HOW TO CHOOSE A SENSOR?▪ Environment: There are many sensors that work well and

predictably inside, but that choke and die outdoors.

▪ Range: Most sensors work best over a certain range of distances. If something comes too close, they bottom out, and if something is too far, they cannot detect it. Thus we must choose a sensor that will detect obstacles in the range we need.

▪ Field of View: Depending upon what we are doing, we may want sensors that have a wider cone of detection. A wider “field of view” will cause more objects to be detected per sensor, but it also will give less information about where exactly an object is when one is detected.

What is an Image Sensor?

▪ Unlike traditional camera, that use film to capture and store an image, digital cameras use solid-state device called image sensor.▪ Image sensors contain millions of photosensitive diodes known as

photosites.▪ When you take a picture, the camera's shutter opens briefly and

each photo site on the image sensor records the brightness of the light that falls on it by accumulating photons. The more light that hits a photo site, the more photons it records. ▪ The brightness recorded by each photosite is then stored  as a set

of numbers (digital numbers) that can then be used to set the color and brightness of a single pixel on the screen or ink on the printed page to reconstruct the image.

What is a Pixel?▪The smallest discrete component of an image or picture on a CRT screen is known as a pixel.▪“The greater the number of pixels per inch the greater is the resolution”.▪Each pixel is a sample of an original image, where more samples typically provide more-accurate representations of the original.

What is Fill Factor?▪ Fill factor refers to the

percentage of a photosite that is sensitive to light.▪ If circuits cover 25% of

each photosite, the sensor is said to have a fill factor of 75%. The higher the fill factor, the more sensitive the sensor.

Complementary Metal Oxide Semiconductor (CMOS)

What is CMOS?▪ “CMOS" refers to both a particular style of digital circuitry design, and the family of processes used to implement that circuitry on integrated circuits (chips).▪CMOS circuitry dissipates less power when static, and is denser than other implementations having the same functionality.▪CMOS circuits use a combination of p-type and n-type metal–oxide–semiconductor field-effect transistors (MOSFETs) to implement logic gates and other digital circuits found in computers, telecommunications equipment, and signal processing equipment.

Basic Operation of CMOS▪ In most CMOS devices, there are several transistors at each pixel

that amplify and move the charge using wires. ▪ The CMOS approach is more flexible because each pixel can be

read individually. ▪ In a CMOS sensor, each pixel has its own charge-to-voltage

conversion, and the sensor often also includes amplifiers, noise-correction, and digitization circuits, so that the chip outputs digital bits.▪ With each pixel doing its own conversion, uniformity is lower.▪ The CMOS image sensor consists of a large pixel matrix that takes

care of the registration of incoming light.▪ The electrical voltages that this matrix produces are buffered by

column-amplifiers and sent to the on-chip ADC

ISOCELL IMAGE SENSOR▪ The key to understanding ISOCELL is the understanding the pixel

technology of the image sensor. Previous sensor technology developments focused on improving the light absorption of each pixel. This has progressed pixel technology from FSI (Front Side Illumination) to BSI (Back Side Illumination). Image sensors with FSI have a similar logic to the human eye where images we see are received first through lenses then transported through wires, and then processed into the signal thanks to the photodetector. FSI, just like human eyes, has certain limitations in terms of the light,  specifically photons, because the light is processed through a wire (nerves) first.▪ The BSI technology solves this problem by reversing the whole

process. Since the photodetectors receive first and can process more light, it improves the light absorption of each pixel, especially in lowlight situations such as night time.

▪ However, as we constantly demand higher resolution for images, the pixel sizes continue to decrease as well, which eventually brings certain limitations to the BSI technology in improving the image quality. For example, since more lights and colors are being absorbed, then being processed, it could result in noise or color mixing between neighboring pixels.▪ This is when ISOCELL, the next generation of pixel technology of

Samsung comes. Basically, ISOCELL technology forms a physical barrier between neighboring pixels – isolating the pixel. The result, compared to conventional BSI pixels, is that the ISOCELL pixels decrease the crosstalk by approximately 30 percent. It also increases the full well capacity (FWC) by 30% and 20% wider chief ray angle. Samsung is the first to adopt the ISOCELL technology.

 

APPLICATIONS

▪ DIGITAL CAMERA▪ PERSONAL DIGITAL ASSISTANCE (PDA)▪ CAMCODERS▪ TOYS AND ROBOTS▪ FINGERPRINT SCANNER▪ Mobile phones

conclusion▪ Image sensors are an emergent solution for practically every automation-focused machine-vision application.▪New electronic fabrication processes, software implementations, and new application fields will dictate the growth of image-sensor technology in the future.

Thank You Very Much For Your Attention