720 likes | 1.35k Views
Image Sensor Technologies. Chris Soltesz SSE Deluxe Sony Electronics, Inc. BPSD. Image Sensor Technologies. An introductory guide to CCD and CMOS imagers. Image Sensors. An image sensor is an electronic device that converts a image (light) to an electric signal.
E N D
Image Sensor Technologies Chris Soltesz SSE Deluxe Sony Electronics, Inc. BPSD
Image Sensor Technologies An introductory guide to CCD and CMOS imagers
Image Sensors • An image sensor is an electronic device that converts a image (light) to an electric signal. • They’re used in digital cameras and other imaging devices. Imagers are typically an array of charge-coupled devices (CCD) or CMOS sensors such as active-pixel sensors (APS).
R Y M WHITE G B C BLUE 1 0 1 0 1 0 1 0 RED 1 1 0 0 1 1 0 0 GREEN 1 1 1 1 0 0 0 0 Color Primaries
Blue Imager Green Imager White Light Red Imager Dichroic Prism
The difference is in the strategies and mechanisms developed to carry out those functions. What is the difference between CCD & CMOS imagers? • Generate and Collect Charge • Measure Charge and turn into voltage or current • Output the signal • Transfer Mechanism
Mechanism Differences CCD Image Sensor Charge-to-voltage Conversion /Amplification Charge Transfer Vertical and Horizontal CCD Amplifier behind Horizontal CCD Light-to-charge Conversion Charge Accumulation Photo Sensor (Light-sensitive Region) of a Pixel Charge-to-voltage Conversion /Amplification Voltage Transfer Amplifier within Pixel Signal Wire (Micro Wire) CMOS Image Sensor Capacitance Equation or C = Capacitance Q = Charge V = Voltage
CCD Image Sensor Photo Sensor (b)(Light-sensitive Region) Pixel (a) Light Charge (Electrons) Vertical CCD (c) Output Amplifier (x) Horizontal CCD (d)
CMOS Image Sensor Pixel (a) Amplifier (y) Photo Sensor (b)(Light-sensitive Region) Light Signal ON ON ON Charge Pixel-select Switch (e) Pixel Row (j) Column Signal Wire(f)(Micro Wire) Column-select Switch (g) Column Circuit (h) Row Signal Wire (i) (Micro Wire) ON Output
CCD Image Sensor Photo Sensor (b)(Light-sensitive Region) Pixel (a) Light Charge (Electrons) Vertical CCD (c) Output Amplifier (x) Horizontal CCD (d)
Charge Transfer- Photo Sensor to Vertical CCD Light Charge (Electrons) Photo Sensor Charge (Electrons) Gate Opens Gate Vertical CCD
Charge Transfer CCD CCD CCD CCD Charge Charge Charge Charge The transfer of charge in a CCD is similar to a bucket-brigade moving water
Amplifier of CCD Image Sensor Voltage Generated on Surface of FD Horizontal CCD Output Output Gate Amplifier Gate Gate Gate Micro Wire Charge Floating Diffusion (FD)
CMOS Image Sensor Photodiode Active-Pixel Architecture (APS) Actual Photodiode Active-Pixel Architecture
CMOS Image Sensor Pixel (a) Amplifier (y) Photo Sensor (b)(Light-sensitive Region) Light Signal ON ON ON Charge Pixel-select Switch (e) Pixel Row (j) Column Signal Wire(f)(Micro Wire) Column-select Switch (g) Column Circuit (h) Row Signal Wire (i) (Micro Wire) ON Output
Voltage Detection Fig. A When Charge is NOT Accumulated in Photo Sensor Fig. B When Charge is Accumulated in Photo Sensor Surface Voltage to Amplifier Surface Voltage to Amplifier Surface Voltage Light Surface Voltage 0 V 0 V Voltage Voltage Charge High Photo Sensor Photo Sensor High
Voltage Detection Fig. C When Charge is NOT Accumulated in Photo Sensor Fig. D When Charge is Accumulated in Photo Sensor Surface Voltage from Photo Sensor Surface Voltage from Photo Sensor Amplified Voltage Amplified Voltage 0 V 0 V V2 Current Signal Voltage V1 V1 Gate Lifts High Gate High
CCD Image Sensor with 2-channel Horizontal CCDs Photo Sensor (Light-sensitive Area) Light Pixel Charge (Electrons) Vertical CCD Output Amplifier 1 Horizontal CCD 1 Channel 1 Horizontal CCD 2 Channel 2 Amplifier 2
CMOS Image Sensor with 3-channel Outputs Photo Sensor (Light-sensitive Region) Amplifier Pixel Light Signal ON ON ON Charge Pixel-select Switch Column-select Switch Output Column Circuit Column Signal Wire (Micro Wire) ON Channel 1 ON Channel 2 Row Signal Wire (Micro Wire) ON Channel 3
Buried-type Photo Sensor Conventional Photo Sensor Free Electron HAL Free Electron Signal Charge Signal Charge
HAD-type CMOS Image Sensor Gate Gate Gate Signal Wire Poly-Si Gate Drain Drain Source P+ (HAL) P+ N P+ N N N P+ N N SiO2 P-type Si (Substrate) Read-out Gate FD Reset Gate FD Reset Drain Photo Sensor Pixel-select Switch Amplifier Floating Diffusion (FD)
Micro Condensing Lens On-chip Micro-lens CCD Sensor Structure Power HAD CCD Hyper HAD CCD
On-Chip-Micro lens On-Chip-Micro lens Internal Lens Photo-Shielding film Photo-Shielding film Poly Si Poly Si Sensor V-register Sensor V-register Fig.-1 Power HAD CCD Sensor Construction Fig.-2 New CCD Sensor Construction Power HAD EX Imager Performance Improvement With New CCD construction Thinner Insulation Film Improvement of Smear with thinner insulation membrane Power HAD CCD camera : -125dB (Typical) Power HAD EX CCD camera : -140dB (Typical)
Pros & Cons of Imagers Feature Comparison
Pros & Cons of Imagers Performance Comparison
Pros & Cons of Imagers Winding Path of CMOS Development's
Image Distortion with CMOS Camera CMOS Camera