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Radiant Vision Systems | A Konica Minolta Company Presented by Shannon Roberts | September 10, 2019 CCD OR CMOS? HOW IMAGING SENSOR PROPERTIES AFFECT PIXEL-LEVE MEASUREMENT OF DISPLAYS

CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

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Page 1: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

Radiant Vision Systems | A Konica Minolta CompanyPresented by Shannon Roberts | September 10, 2019

CCD OR CMOS? HOW IMAGING SENSOR PROPERTIES AFFECT PIXEL-LEVE MEASUREMENT OF DISPLAYS

Page 2: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

Global SupportAutomated Visual InspectionLight & Color

Page 3: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

3Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

TODAY’S AGENDA

• “We Need More Pixels”

• Improving Visual Experiences in Displays

• Importance of Pixel-Level Measurement

• Capturing Unique Pixels (Measurement Resolution)

• Capturing Repeatable Data (Measurement Noise)

• Imaging System Specifications

• Optimizing Resolution and Noise

• CCD versus CMOS performance

• Summary

Page 4: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

“WE NEED MORE PIXELS”Improving Visual Experiences in Displays

Page 5: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

5Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

“WE NEED MORE PIXELS”

Source: [Charbax]. (2017, June 8). Google Keynote at SID Display Week, Clay Bavor, VP of Google VR/AR [Video File]. Retrieved from https://www.youtube.com/watch?v=IlADpD1fvuA

Page 6: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

6Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

REPLICATING REALITY

• Bavor, on VR: “An actual-reality headset with 20/20 vision …that's what we're going for.”

20/20

20/100*

*20/200 = legally blind

Page 7: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

7Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

BENEFITS OF “WAY, WAY MORE PIXELS”

• Pixel size / density

• Greater detail in the same area

10x10 20x20 50x50

Page 8: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

IMPORTANCE OF PIXEL-LEVEL MEASUREMENTChallenges Capturing Accurate Pixel Values

Page 9: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

9Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

IMPORTANCE OF MEASUREMENT

• Pixel Defects:

• Stuck on, off (dead) pixels

Page 10: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

10Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

IMPORTANCE OF MEASUREMENT

• Pixel Defects:

• Non-uniform pixels

MicroLED Display

OLED Display

Page 11: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

11Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

IMPORTANCE OF MEASUREMENT

• Pixel Defects:

• Non-uniform pixels

Pixel-level variation Actual OLED measurement

(luminance in false color)

Page 12: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

12Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

OBJECTIVES IN MEASUREMENT

Sufficiently Isolate Each Pixel(Measurement Resolution)

Repeatability Across All Pixels(Measurement Signal to Noise)

10x10

Page 13: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

IMAGING SYSTEM SPECIFICATIONSOptimizing Resolution and Signal-to-Noise Ratio

Page 14: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

14Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

IMAGING PHOTOMETERS

• Full display analysis.

• Actual measurements shown with luminance (brightness) in false color scale.

Page 15: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

15Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

IMAGING SYSTEM SENSORS

Representation ofSensor Pixels

One Sensor Pixel

Page 16: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

16Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

OBJECTIVES IN MEASUREMENT

Sufficiently Isolate Each Pixel(Measurement Resolution)

Repeatability Across All Pixels(Measurement Signal to Noise)

10x10

Page 17: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

17Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

MEASUREMENT RESOLUTION

• What if we don’t have sufficient image resolution?

3x3 sensor pixels: 1 display pixel

Page 18: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

18Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

MEASUREMENT RESOLUTION

• What if we don’t have sufficient image resolution?

6x6 sensor pixels: 1 display pixel

Page 19: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

19Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

MEASUREMENT NOISE

• What if we have too much image noise?

Page 20: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

20Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

THE ARGUMENT FOR LARGE SENSOR PIXELS

• Photon Shot Noise

• Random statistical variation of photons captured by a sensor

• Pixel Well Capacity

• The amount of electron charge a pixel can hold

• Full well capacity = pixel saturation

P

PP

Well

Pixel Size

Photons per μm2

P P

P P

P

e-e-e-e- e- e-e-e-e-e- e- e-e-e-e-e- e- e-e-e-e-e- e- e-e-e-e-e- e- e-

e-e-e-e- e- e-e-e-e-e- e- e-e-e-e-e- e- e-e-e-e-e- e- e-e-e-e-e- e- e-

e-e-e-e- e- e-e-e-e-e- e- e-e-e-e-e- e- e-e-e-e-e- e- e-e-e-e-e- e- e-

e-e-e-e- e- e-e-e-e-e- e- e-e-e-e-e- e- e-e-e-e-e- e- e-e-e-e-e- e- e-

e-e-

LIGHT

Saturation(e-)

Page 21: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

21Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

EFFECT OF SENSOR RESOLUTION

Increasing resolution within same sensor area => Smaller Pixels

Page 22: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

22Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

LIMITS ON SENSOR SIZE

Page 23: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

23Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

RESOLUTION VS. NOISE

Low Resolution, Low Noise High Resolution, High Noise

Page 24: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

24Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

RESOLUTION VS. NOISE

Optimize Resolution vs. Noise

Page 25: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

CCD VS. CMOS IMAGINGComparison of Today’s Technologies for Pixel Measurement

Page 26: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

26Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

CCD VS. CMOS SENSORS

= photo-sensing unit = decode & readout= readout electronics

CCD Sensor CMOS Sensor

Page 27: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

27Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

HOW TO COMPARE IMAGING PERFORMANCE?

Specification Value

Sensor Type CCD

Resolution (Megapixels)

50.6

Sensor Pixels 8712 x 5813

Bit Depth 12 bit

System Accuracy

Illuminance ± 3%; Luminance (Y) ± 3%

CCD Imaging System CMOS Imaging System

Specification Value

Sensor Type CMOS

Resolution(Megapixels)

50.6

Sensor Pixels 8712 x 5813

Bit Depth 12 bit

System Accuracy

Illuminance ± 3%; Luminance (Y) ± 3%

Page 28: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

28Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

PHOTON TRANSFER CURVE (PTC) METHOD

Page 29: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

29Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

PHOTON TRANSFER CURVE (PTC)

Full Well

Slope = 1/2

LOG (Signal)

LO

G (

Nois

e)

Page 30: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

30Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

CCD VS. CMOS PHOTON TRANSFER CURVE (PTC)S

IG

NA

L T

O N

OIS

E

SIGNAL [e-]

• CCD Realized • CMOS Realized — Perfect System

Full Well (CMOS) Full Well (CCD)

Page 31: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

31Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

DETECTING SUBTLE VARIATIONS IN LIGHT

• Large pixels have a greater well

capacity

• High electron count is necessary

to discern sub-percent variation

in luminance

• SNRMax < Sqrt(Well Size)

• More than 10ke- are needed for a

1% difference detection

Page 32: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

32Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

CCD VS. CMOS ACROSS LUMINANCE LEVELS

• We need to measure displays at bright state and dark state

• With larger well capacity, CCDs can detect extremely subtle variations (<1% pixel-level variation) at both bright and dark states CMOS CCD

Page 33: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

33Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

HOW CAN YOU TELL?

Page 34: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

34Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

CCD VS. CMOS SUMMARY

CCD Benefits

• Signal to Noise Ratio

• Larger well capacity, acquiring more photons per pixel

• Repeatability

• Performance at All Levels of Saturation

CMOS Benefits• Speed• Photo-sensors and

amplifiers are within the same cell

• Cost• Can be produced on any

standard silicon production line

• Performance at Low Levels of Saturation

Page 35: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

35Radiant Vision Systems | A Konica Minolta Company

© Radiant Vision Systems, LLC.

THE MOST ACCURATE IMAGING SOLUTION FOR PIXEL-LEVEL MEASUREMENT (CURRENTLY)

• CCD sensors • Best balance of resolution/noise

• Excellent light sensitivity

• Repeatable (fewer false positives/negatives)

• More accurate measurement pixels per display pixel

• More reliable data across bright states or gray levels

Page 36: CCD OR CMOS? HOW IMAGING SENSOR …...CCD VS. CMOS SUMMARY CCD Benefits • Signal to Noise Ratio •Larger well capacity, acquiring more photons per pixel •Repeatability • Performance

Radiant Vision Systems | A Konica Minolta CompanyRadiant Vision Systems | A Konica Minolta CompanyQuestions? Contact [email protected]

THANK YOU!