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A Low-Cost Large-Size Document Scanner


First published on: 1-9-2011

A Low-Cost Large-Size Document Scanner

Mandar Thite developed a low-cost scanner priced 10 times lower than scanners currently available in the market


Mandar Thite demonstrating his photo clipping machine

Design engineer Mandar Thite had many old newspapers stocked in his house as his father loved collecting newspaper clippings. Some of these were even over thirty years old. Thite wanted to immortalise these clippings by creating digital copies. However, he found that scanning such large format papers would cost him a hefty sum of Rs 100 per sheet.

Thite decided to experiment with his 7.2-megapixel Canon Powershot A550 digital camera. He found that if he could digitally clip the captured images, it could turn out much cheaper. He developed a simple mechanism using easily available components like a camera, magnetic push-pull solenoid, permanent magnet DC motor and cycle tube along with a time synchronisation technique.

The scanner is created using a retrofit attachment for a digital camera using a magnetic solenoid, motors and a rubberised roller. The apparatus includes a digital camera, a stand to hold it and a mechanism to feed documents to the camera continuously, so that these can be photographed. The digital scanner consumes only 15 watts of power. This innovation was recognised as one of the top five winners of ‘The Next50 Global Innovation Challenge’—an IIT Kanpur initiative.

How it works

In existing digital scanners images are captured by a charge-coupled device (CCD) array. A lamp is used to illuminate the document and the image of the document reaches the array through a series of mirrors, filters and lenses. The exact components vary according to the scanner models but the components are pretty much the same.

In Thite’s digital scanner, a camera is mounted over a platform and a magnetic push-pull solenoid is fixed next to it. With power supply the solenoid gets pushed towards the camera’s click button. The camera clicks a photograph of the document and instead of the lamp the flash provides the light. The image gets stored on its memory card. Though the solenoid and motorissed roller are two separate units, these are synchronised to work together. These have separate controls with suitable 12V DC power supply. The maximum print-size depends on the area the camera can capture.

On the lower platform, the mechanism used is similar to that of a printer. Paper is fed into the machine by using a roller feeding system. The feed mechanism consists of an electrical motor for which power is required. A rubberised roller—in this case a PVC pipe wrapped with a simple cycle wheel’s tube—is placed at the top of the papers. It is controlled by a 12-watt motor which rolls out paper soon after the camera captures the image. The tube rolls out the scanned document from the platform and the next document is ready before the camera.

“In other large-size document scanners there is no provision for sheet-feeding. Here, the papers are fed onto the platform with the roller,” Thite reveals. The next cycle begins as the camera clicks an image of the new document.

For transferring photographs to the computer system, Thite used the camera’s software. After transferring the images to computer, text can be extracted by using an optical character recognition (OCR) software.

Challenges that Thite faced

Time synchronisation between the camera, solenoid and roller is one of the essential elements of this digital scanner. Thite bought timer circuits and integrated a time sequence that matched the process into it. The timers have been set such that there is a three-second gap between the camera-click and the roller movement. This time interval gives the camera enough time to charge its flash.

“I have used three timers—for the camera to click, for the motor that rolls the paper out and for the time interval that stands between the two. At first, the roller moved the paper too fast and the camera was not given enough time to click the image. I tried different time configurations and finally found the required time interval, i.e., three seconds,” Thite explains.

Another area that required improvisation was the camera-click. “I first used a motor for the click mechanism but the speed of the click was low. I then decided to try a magnetic push-pull solenoid and found that it works well,” Thite explains.

The cost factor

Already available large document scanners will cost you at least Rs 200,000. “If you look at my final prototype, I have spent about Rs 3000 on the attachment by using standard parts available in the market and other components. I fitted the attachment to a digital camera that cost around Rs 7000. So the total attachment cost me about Rs 10,000,” Thite reveals. However, he intends to use more advanced components in the final product.

What lies ahead

Thite is working on a saleable model of the scanner that can be used in libraries and by architects. “I am also looking for investors who can take this innovation forward and push it to the market,” Thite concludes.

The author is from EFY Bureau, Bengaluru


commentPost Comment | 9 Comments

jatin   1199 days ago

Cant we just click the photos by ourselves ?? whats the difference between the output scanned copy of this arrangement and the photo taken my camera ??
commentReply   3 Replies
Dr.Premkumar   831 days ago

Mr Thite great idea. I have tried to take copy of a large book copy not available. i used a digital camera to take manual pictures. But it was a larger file for a reasonable resolution then i discarded the attempt. I think you may utilize some logic gates or some EPROMs in controlling the activities. Best wishes.
Vikas   718 days ago

Hi Jatin Yes you can just click a document using your camera. The difference in image depends on your camera settings. Initially you have to do hit and trial to get the exact settings of distance between document and camera light source placement. Also the document to be clicked has to be flattened to remove all the wrinkles otherwise the image will have dark and bright areas. Depending on your requirements you may have to crop this image using MS Paint or other standard imagephoto editor. But for most purposes the image is real good. Printouts can be taken by transfering the image to PC then then using the ocnnected printer. Alternately if your camera and printer supports bluetooth the image can directly be printed from camera.
a   856 days ago

it will not capture the image in 11 ratio so it is not useful for technical purposes and for architects
commentReply   1 Reply
rubesh   761 days ago

if the paper is glossy wont the flash show as a glare in the photo ? A separate light source from an angle may be used..
commentReply   1 Reply
Vikas   718 days ago

Yes most of the time a table lamp with white light source like CFL or LED lamp will suffice. However placement of this light source is important.
Yogesh Palkar   753 days ago

Please supply contact detail of Mr. Mandar Thite for scanner procurement.
Vikas   718 days ago

I have been using this technique since a long time to make copies of documents ranging from A4 to larger sizes. I have been using normal regular photography cameras with variable zoom. This gives perfect focus and desired sharpness. Yes lightening has to be provided from an angle to omit the flash brightness. For this I place the document on a table and provide the light by placing a table lamp having CFL or LED white light source. Believe me effects are real good. Now no need to rush to market to get a document photocopied. But this technique can be used only for a limited number of documents as you have to feed documents manually. Printouts can be taken using a printer connected to PC. You can use normal MS-paint or any other image editor to crop the image as per your needs.
Murugan   293 days ago

i am also using my digital camera to take soft copy of certificates. but the size balancing is critical

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