ECE 5320:Mechatronics Assignment#1 Topic: CCD AND CMOS IMAGE SENSORS Prepared by: Sandeep Sharma Dept of Electrical and Computer Engineering Utah State UniversityOUTLINEREFERENCESIMAGE SENSORSCCD AND CMOS IMAGE SENSORSCCD IMAGE SENSORSSlide 7Slide 8CMOS IMAGE SENSORSCCD VS CMOS SENSORSlide 11Slide 12Slide 13Slide 14Slide 15APPLICATIONSSlide 17Slide 18Slide 19SUMMARYCCD VS CMOSECE 5320:MechatronicsECE 5320:MechatronicsAssignment#1Assignment#1Topic: CCD AND CMOS IMAGE SENSORSTopic: CCD AND CMOS IMAGE SENSORSPrepared by: Sandeep SharmaPrepared by: Sandeep SharmaDept of Electrical and Computer EngineeringDept of Electrical and Computer EngineeringUtah State UniversityUtah State UniversityOUTLINEOUTLINEIMAGE SENSORSIMAGE SENSORSCCD SENSORSCCD SENSORSCMOS SENSORSCMOS SENSORSCCD VS CMOS IMAGE SENSORSCCD VS CMOS IMAGE SENSORSAPPLICATIONSAPPLICATIONSSUMMARYSUMMARYREFERENCESREFERENCESIMAGE SENSORSIMAGE SENSORSHOWSTUFF: UNDERSTANDING THE HOWSTUFF: UNDERSTANDING THE DIFFERENCE BETWEEN CCD AND DIFFERENCE BETWEEN CCD AND CMOS IMAGE SENSORSCMOS IMAGE SENSORSTHE IMAGE SENSOR MARKETTHE IMAGE SENSOR MARKETIMAGE SENSORSIMAGE SENSORSUnlike traditional camera, that use film to capture and store Unlike traditional camera, that use film to capture and store an image, digital cameras use solid-state device called an image, digital cameras use solid-state device called image sensorimage sensorImage sensors contain millions of photosensitive diodes Image sensors contain millions of photosensitive diodes known as photositesknown as photositesIn the brief flickering instant that the shutter is open, each2 In the brief flickering instant that the shutter is open, each2 photosite records the intensity or brightness of the light photosite records the intensity or brightness of the light that falls on it by accumulating a charge; the more light, the that falls on it by accumulating a charge; the more light, the higher the charge. higher the charge. The brightness recorded by each photosite is then stored2 The brightness recorded by each photosite is then stored2 as a set of numbers that can then be used to set the color as a set of numbers that can then be used to set the color and brightness of dots on the screen or ink on the printed and brightness of dots on the screen or ink on the printed page to reconstruct the image page to reconstruct the imageCCD AND CMOS IMAGE SENSORSCCD AND CMOS IMAGE SENSORSUntil recently, CCDs were the only image sensors used in Until recently, CCDs were the only image sensors used in digital cameras. digital cameras. They have been well developed through their use in They have been well developed through their use in astronomical telescopes, scanners, and video camcorders. astronomical telescopes, scanners, and video camcorders. However, there is a new challenger on the horizon, the However, there is a new challenger on the horizon, the CMOS image sensor that promises to eventually become CMOS image sensor that promises to eventually become the image sensor of choice in a large segment of the the image sensor of choice in a large segment of the market.market.CCD IMAGE SENSORSCCD IMAGE SENSORSA charge-coupled device (CCD) gets its A charge-coupled device (CCD) gets its name from the way the charges on its name from the way the charges on its pixels are read after an exposure.pixels are read after an exposure. After the exposure the charges on the first After the exposure the charges on the first row are transferred to a place on the row are transferred to a place on the sensor called the read out register. sensor called the read out register. From there, the signals are fed to an From there, the signals are fed to an amplifier and then on to an analog-to-amplifier and then on to an analog-to-digital converter. digital converter.CCD IMAGE SENSORSCCD IMAGE SENSORSOnce the row has been read, its charges on the readout Once the row has been read, its charges on the readout register row are deleted, the next row enters, and all of the register row are deleted, the next row enters, and all of the rows above march down one row. rows above march down one row. The charges on each row are "coupled" to those on the row The charges on each row are "coupled" to those on the row above so when one moves down, the next moves down to above so when one moves down, the next moves down to fill its old space. fill its old space. In this way, each row can be read-one row at a time.In this way, each row can be read-one row at a time.The CCD shifts one whole row at a time into the readout register. The The CCD shifts one whole row at a time into the readout register. The readout register then shifts one pixel at a time to the output amplifierreadout register then shifts one pixel at a time to the output amplifier..CMOS IMAGE SENSORSCMOS IMAGE SENSORS In most CMOS devices, there are several In most CMOS devices, there are several transistorstransistors at at each pixel that amplify and move the charge using more each pixel that amplify and move the charge using more traditional wires. traditional wires. The CMOS approach is more flexible because each pixel can The CMOS approach is more flexible because each pixel can be read individually. be read individually. In a In a CMOSCMOS sensor, each pixel has its own charge-to-voltage sensor, each pixel has its own charge-to-voltage conversion, and the sensor often also includes amplifiers, conversion, and the sensor often also includes amplifiers, noise-correction, and digitization circuits, so that the chip noise-correction, and digitization circuits, so that the chip outputs digital bits. These other functions increase the outputs digital bits. These other functions increase the design complexity and reduce the area available for light design complexity and reduce the area available for light capture. With each pixel doing its own conversion, capture. With each pixel doing its own conversion, uniformity is lower. uniformity is lower.CCD VS CMOS SENSORCCD VS CMOS SENSORCMOS image quality is now matching CCD quality CMOS image quality is now matching CCD quality in the low- and mid-range,
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