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Testing Camera Modules in Consumer Electronics with NI LabVIEW, Data Acquisition

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The CMOS Image Sensor is Capable of AccuratelyTesting Camera Modules on Increasingly Small Consumer Products.

Author(s):
Soh Wee Kian - iNetest Resources Pte Ltd

Industry:
Consumer Goods, Imaging Equipment, Electronics

Products:
LabVIEW,

The Challenge:
Designing a test solution specifically for the small camera modules available in products such as mobile phones, PDAs, and digital cameras.

The Solution:
Using National Instruments LabVIEW software and data acquisition hardware to customize a complementary metal-oxide semiconductor (CMOS) image sensor for camera modules that economically assures quality and improves time to market for products with integrated camera modules.

"Based on our experience of using NI virtual instrumentation tools, we are able to develop our products 60 to 70 percent faster than traditional methods. Our customers have communicated their appreciation for our cost-effective, turnkey solutions in a product line we are currently developing using our NI virtual instrumentation knowledge."

In recent years, the demand for high-quality camera modules in consumer products has increased significantly. Naturally, this means manufacturers must find camera modules that are cost-effective, offer shorter time to market, and ensure quality performance to be integrated into their own products.

Business Aspects of Having Effective Quality Assurance Tools

Traditionally, the CMOS image sensor undergoes wafer-level testing, which is typically expensive and time-consuming. These increasingly small (usually about the size of a fingernail) CMOS image sensors pose a significant challenge to test the camera module with conventional test and measurement techniques. Cost, time to market, and quality are major factors to consider for test.

Usually, manufacturers have an incoming quality control (IQC) department to assess the reliability and quality of the received CMOS image sensor. Depending on the volume of the manufacturer’s product outputs and projections, it is virtually impossible to test every single CMOS image sensor.

For this reason, it is extremely important for sensor manufacturers to produce their products with the maximum yield rate to add value down the supply chain. This also helps them make sure that their products meet the industry’s quality standards and gain easy acceptance into the manufacturer’s IQC department.

Using NI products, an industrial PC, and test and measurement algorithms developed in-house, we have devised a system that makes testing camera modules easier than ever.

With our extensive experience in test and measurement, we created a highly customizable CMOS image sensor for specific camera modules being tested.

There are essentially two core phases in our camera module testing. First, we run an electrical test on the printed circuit board assembly (PCBA) portion of the camera module to ensure its proper functionality. In the second phase, we control the camera module lens via the access points of the module itself. There, we capture images and perform numerous checks of the images captured using NI equipment and analytical software with reference to a sample image.

Measurement Specification and Imaging Process Technique

The test covers the following phases:

Electrical Testing Phase

  • Open/short test
  • Current and voltage test

Image Quality Testing Phase

  • Modulation transfer function (MTF)
  • Signal-to-noise ratio (SNR)
  • Defect and blemish
  • Shading
  • Chromatic aberration
  • Color accuracy

The imaging technique involves using the MTF as the main algorithm to detect the sharpness of the image.

 

MTF50(line widths/inch on the print) =

MTF50(LW/PH)

Print height in inches

For future use, we want to design the system to test multiple modules in parallel using the next generation of IMAQ vision development equipment and analysis software. By doing this, we could help manufacturers achieve their shorter time to market, cost reduction, and quality assurance goals.

Based on our experience of using NI virtual instrumentation tools, we are able to develop our products 60 to 70 percent faster than traditional methods. Our customers have communicated their appreciation for our cost-effective, turnkey solutions in a product line we are currently developing using our NI virtual instrumentation knowledge.

There are several fundamental advantages of getting integrators like iNetest Resources to build testers. First, we improve time to market for products. Customers can depend on us to deliver testers without investing considerable time and resources in their own functional tester development. NI has helped iNetest Resources simplify the manufacturing process for our customers so they can effectively meet their business objectives and increase profits.  .

 

For more information, contact:

Soh Wee Kian

iNetest Resources Ltd.

1003 Bukit Merah Central, #07-06

Technopreneur Centre, Singapore 159-836

Tel: 65 6376 2268

Fax: 65 6376 2269

E-mail: wk.soh@inetest.cn

 

 

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