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I'm going to make a device which will take a picture from a paper which contains a line of English characters and then process the picture with OCR to get some information in micro-controller. My idea is to make a dark enclosure consist of a an image sensor inside it and a glass on top like a scanner but very simple. I have done it before with a generic camera (genius facecam x1000) and lighting with some led arrays and then connected to PC.

Now i need to make it an industrial product for special uses. I need my device to be as simple and compact as possible and I need to omit extra costs from this design. as i don't have any experience in optic i have some questions:

  • Is a B/W IR CMOS suitable to do such a design?
  • If i use some of these image sensor modules like this link, are the infrared LEDs on the board enough to make a qualified picture to be processed by OCR?
  • If I am totally going in wrong way, what is the best choice that will do my job with lowest price and is industrial? what kind of lighting is needed?
  • If I use an image CMOS sensor, is any lens or special prism needed?

I just need a normal quality image of the paper and the ease of communicating with the sensor is an important factor to me.

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  • \$\begingroup\$ Nice spec. Write it in your brochure: normal quality. \$\endgroup\$ Commented Apr 18, 2017 at 18:14

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  1. CCD sensors are inherently more sensitive to IR than CMOS...part of the advantage of CMOS sensors for "normal" cameras is that they don't have as much inherent "IR preference," so less IR filtering is required to take "visible spectrum" photographs.

  2. Usually, any image sensor that comes with its own IR LEDs will be producing FAR MORE IR illumination than you need for reading a sheet of paper right in front of the imager...you'll probably have to add series resistors to the LEDs to reduce their output and keep them from "washing out" your images.

  3. IMHO, you should **not* use a "camera" to scan something on a flat surface; a line scan sensor/linear CCD is the more appropriate tool for the job (similar to a camera, but only 1 row of pixels on the sensor, and easier to focus on a closer "target"). Here's One for an example of a device that should work better.

  4. If you use a CMOS image (rather than linear) chip, then you'll need to look at finding a "wide-angle macro" type lens to enable the imager to "see" the whole sheet of paper, and also focus, at any reasonably close range.

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