DEFINING A SPARKLE MEASUREMENT STANDARD FOR QUALITY ... · 4/3/2018 · • Define measurement...

Radiant Vision Systems | A Konica Minolta CompanyRadiant Vision Systems | A Konica Minolta CompanyPresented By Matt Scholz | April 3, 2018

DEFINING A SPARKLE MEASUREMENT STANDARD FOR QUALITY CONTROL OF ANTI-GLARE DISPLAYS

Global SupportAutomated Visual InspectionLight & Color

3Radiant Vision Systems | A Konica Minolta Company

TODAY’S AGENDA

• Anti-Glare Displays

• Background and Application

• Effect of Sparkle on Display Quality

• Measuring Sparkle: Considerations

• Creating a Standard Measurement Method

• System Specifications

• Measurement Setup

• Software Testing

• Defining Tolerances based on Human Perception

• Customer Success Story

ANTI-GLARE DISPLAYSBACKGROUND AND EFFECT ON VISUAL DISPLAY QUALITY

VIEWING DISPLAYS IN AMBIENT LIGHT

SOLUTION: ANTI-GLARE

LCD with AGLCD without AG

ANTI-GLARE DISADVANTAGE

Anti-Glare MicrostructureNuijs, Horikx, Applied Optics 33,18 (1994) p.4058

LCD with AG

OPTIMIZING THE AG LAYER

Evenly-diffused Sunlight Sparkle

11 12 13

MEASURING SPARKLE

• Pixel-level luminance variation calculated using standard deviation (σ) of a population

• Measured as a % deviation across a region or averaged for multiple regions (ROI)

MEASUREMENT CONSIDERATIONSADVANTAGES FOR ACHIEVING DATA REPEATABILITY

OBJECTIVES FOR EVALUATION

1. Effective display characterization

• Define measurement system

• Define measurement setup

• Isolate sparkle

• Reduce effects of other display anomalies

2. Evaluation based on human perception

• Perform initial human evaluation

• Correlate system measurements with human rankings

1. EFFECTIVE DISPLAY CHARACTERIZATION

Reduce effects of display gradient

Register active display area (RADA)

Reduce other display anomalies

Color Variation (if required)

• CIE-matched tristimulus color filters

• Color calibration

2. EVALUATION BASED ON HUMAN PERCEPTION

Define Tolerance Using Several Participants

Define Tolerance Case by Case

Customer A Suppliers X, Y, Z

CREATING A STANDARD METHODHOW TO ACHIEVE REPEATABLE SPARKLE MEASUREMENT FOR AG DISPLAYS

SYSTEM SPECIFICATIONS

• ProMetric® Camera:

• I-series imaging colorimeter

• Y-series imaging photometer

• High resolution (to 29MP)

• 61 dB dynamic range

• Per pixel, 1x1 binning

• Thermoelectrically-cooled sensors

• High SNR

• Factory calibration

• 50mm electronically-controlled lens

SYSTEM SPECIFICATIONS

• TrueTest™ Software

• Data acquisition & analysis

• Test sequencing

• RADA

• Gradient filter

• Blob removal

HOW TO SET UP THE MEASUREMENT

1. To ensure stability, use breadboard and lock down the display

and camera.

2. Measure to the location where

grey meets black on both sides

of the camera (CCD plane).

CCD Plane

3. The distance from side to side should be equal to ensure the

camera and the display are parallel.

CCD Plane

4. Measure using the offset of physical to focus distance from the

screen to the CCD plane of the camera.

CCD Plane

< 0.1 mm

< 0.5°

< 0.5°< 0.5°

5. Check Alignment of the Display

• The display must be centered at the camera’s optical axis, with no rotation or tilt

- x < 0.1 mm / y < 0.1 mm

- Axial rotation < 0.5° / Horizontal tilt < 0.5° / Vertical tilt < 0.5°

• Display orientation is measured by the software

SPARKLE ALIGNMENT

Example Application:Software alignment window refreshing the angular & offset measurement by localizing the 5 dots

6. Double-check Focus Mode in software to ensure you are

centered in the display.

CCD Plane

7. Set the display to green.

8. Ensure all ambient light is removed.

9. Using the Sparkle Measurement Setup in software, take a

measurement and record the value.

10. Adjust the exposure for the Y filter in software.

TAKING A MEASUREMENT

Using the Subframe Tool in software, create a subframe of

500x500 pixels located at the center of the display.

Analysis AreaSub frame

SOFTWARE TEST

TrueTest Random Mura Algorithm

• Standard deviation of a population – Avg for all ROI

SOFTWARE TEST

DEFINING ACCEPTABLE TOLERANCES

1 2 3 4 5 6 7 8 9 10

Human Observers

Display A

Human Ranking 10 (best) ≈ Measured Sparkle Value 1.36%

Human Observers

1 2 3 4 5 6 7 8 9 10

Display B

Human Ranking 7 (acceptable) ≈ Measured Sparkle Value 2.21%

Human Observers

1 2 3 4 5 6 7 8 9 10

Display C

Human Ranking 6 (poor) ≈ Measured Sparkle Value 3.05%

Human Observers

1 2 3 4 5 6 7 8 9 10

Display C

Human Ranking 6 (poor) ≈ Measured Sparkle Value 3.05%

Acceptable tolerance 2.21%

MEASUREMENT RESULTSCAMERA-TO-CAMERA & CAMERA-TO-HUMAN REPEATABILITY

RADIANT DISPLAY TESTING

SYSTEM USED 1 2 3 4 5 6 7 8 9 10 AVG

I16 .5M DISPLAY C

500X500 SN 31523.624 3.618 3.611 3.613 3.616 3.613 3.606 3.607 3.613 3.6 3.6121

I16 .5M DISPLAY B

500X500 SN 31522.87 2.854 2.871 2.83 2.86 2.808 2.756 2.843 2.809 2.878 2.8379

I16 .5M DISPLAY A

500X500 SN 31522.472 2.469 2.474 2.453 2.475 2.45 2.47 2.469 2.474 2.468 2.4674

1 2 3 4 5 6 7 8 9 10 AVG

I16 .5M DISPLAY C

500X500 SN 5553.652 3.691 3.686 3.692 3.68 3.684 3.679 3.69 3.696 3.681 3.6831

I16 .5M DISPLAY B

500X500 SN 5552.973 2.971 2.964 2.968 2.975 2.967 2.984 2.968 2.971 2.975 2.9716

I16 .5M DISPLAY A

500X500 SN 5552.57 2.563 2.563 2.57 2.561 2.563 2.585 2.578 2.588 2.588 2.5729

SYSTEM REPEATABILITY

DUT% diff Camera to

Camera

Display A 1.95%

Display B 4.60%

Display C 4.19%

Camera To CCD Plane (m) Focus Distance (m) Display C

I29 0.483 0.5 3.424

I16 0.483 0.5 3.417

I8 0.483 0.5 3.48

I2 0.483 0.5 3.452

RESOLUTION REPEATABILITY

SPARKLE MEASUREMENT RESULTS

Maximum Pixel Variation %for a single display

CUSTOMER SUCCESS STORYSPARKLE MEASUREMENT CORRELATED TO HUMAN VISUAL PERCEPTION

SUPPLIER IQC/OQC STANDARDS

SPARKLE IN SUPPLIER DISPLAYS

Without AG layer With AG layer

0 1 2 3 4 5 6 7 8 9 10

Radiant Camera (Sparkle) Rating

SPARKLE/HUMAN CORRELATION

DIRECTIVE FOR STANDARD MEASUREMENT

“Moving forward, all suppliers must use Radiant’s Sparkle Solution.”

SUMMARY

✓ Anti-glare layers improve display visibility in reflective light, but

introduce sparkle, which can affect perceived quality of the display.

✓ Lack of a repeatable measurement method for sparkle has been a

barrier to defining standard quality control processes.

✓ A method employing a Radiant ProMetric imaging system, TrueTest

Software, and defined setup criteria has been proven at automotive

OEM facilities for repeatability with direct correlation to human perception.

✓ Using this method, OEMs and manufacturers of displays can set precise

tolerances for sparkle and define standards for quality control.

Radiant Vision Systems | A Konica Minolta CompanyRadiant Vision Systems | A Konica Minolta CompanyQuestions? Contact Info@RadiantVS.com

THANK YOU!

DEFINING A SPARKLE MEASUREMENT STANDARD FOR QUALITY ... · 4/3/2018 · • Define measurement...

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