How to choose appropriate scanner for scanning at DMS entry point (workgroup and departmental scanners)

Product:	IMiS/Scan, IMiS/Scan++, IMiS/BatchScan
Release:	All
Date:	01/03/2017

Case:

We come across many different documents during scanning process.
A wide range of documents of different sizes and thickness call for a scanner with capable ADF. The ADF unit and a optical sensor are crucial components. To choose the scanner that will fulfil the working process needs, we have to consider the following:

Description:

The drivers

When making a decision for Document Management System in company, one has to consider the reliability and the level of support that will be needed during a lifetime of DMS. Document imaging component as a part of DMS has to have a reliable support. Choosing a scanner with weak support or drivers that do not go trough a certification path might be a weakness that will affect the DMS stability. At a present time only ISIS scanner drivers are certified and supported by IMiS products. Make sure that the scanner you are buying has EMC certificated ISIS driver provided.

The ADF

The ADF's are of two types reversing automatic document feeder or RADF, which scans one side of a page, then flips it and scans the other side. A duplexing automatic document feeder or DADF scans both sides in one pass.
RADFs are nowadays found in older, cheaper scanners because they slowed down the scanning process and were prone to feeding problems which ended in document shredding occasionally.
The DADF is more suitable for document scanners since both sides of paper are scanned in one pass, which doubles the scanning speed and the possibility of document damage is less possible.
Most newer scanners are equipped with DADF, but they still differ in sheet separation method and the straightness of the document path through the ADF. The sheet separator can be roller based and the brake pad based. The roller based separators are usually preforming faster and the separation of sheets is more precise.
So best ADFs are the ones with the "one pass" with roller based separator where document travels as strait as possible trough the ADF. Usually on a workgroup or departmental scanner's ADF one can stack up to 50 80 g/m² paper sheets.

The optical sensor

Three types of sensors are in use in document scanners, the CCD, CMOS and CIS (Contact Image Sensor). The main differences are the price, the colour depth they can deliver, the light source and the distance the optical sensor is positioned form the media (paper sheet). The CIS sensors deliver lesser colour depth and the light source used are usually RGB light emitting diodes. CIS sensors are usually line sensors that consume less energy for operation and are easier to produce There's no need for extra optics (lens and mirrors) which is needed for CMOS and CCD sensors. If the scanner will be used for scanning documents that differ greatly in thickness (personal ID cards or banking cards along with normal paper documents), one should check the thickness range capabilities of the scanner, since scanners with CIS sensors have limited capabilities.
The light source used in case of CMOS and CCD sensors in the past were mostly white cold cathode discharge lamps, which had to preheat before scanning (up to 30 seconds), but today almost all scanners use white LED array that powers on almost instantly.
The CCD sensors provide best image quality and scanning speeds, but are costly and consume more energy for operation than CMOS or CIS.
For usual scanning purposes in workgroup environment, scanning at 300 DPI black&white, all of those sensors preform sufficiently. When there's a need for high volume and high speed scanners with better image quality the best option is the scanner with CCD sensor.

The volume of documents scanned daily

Every document scanner has the estimated daily duty cycle. The number tells us the quantity of standard paper pages that can be scanned per day and tells us of scanning speed and ADF endurance. Workgroup scanners daily duty cycle starts ad 1500 pages, the number for departmental scanners starts at 4000 and goes up to 9000. Most workgroup or departmental scanners with roller based ADF separator would successfully separate paper sheets of 27 g/m² to 1.4mm thick ID or bank cards. The nonroller based ADFs support lesser thickness range, but most are still sufficient for most documents. It's not unusual for companies to utilise several departmental scanners instead of a few high volume scanners. The maintenance could be cheaper and the distribution of work among more scanning stations can be more efficient.

The ergonomics point of view

One should consider the workplace the scanner is occupying. We can find scanners that incorporate ADF and flatbed in a same housing, but there are scanners with separate flatbed unit. The choice we'll make depends greatly of a document types we'll need to scan. For scanning separate sheets of standard paper documents the scanner with ADF is sufficient. Those scanners are smaller and occupy less space. The scanners with separate flatbed can occupy up to 3 times more space and up to 2 times more space compared to scanners with flatbed built in same housing.

The image processing (IP) software provided with scanner

Many document scanners have some IP functionalities incorporated in scanner driver, others use IP software such as Kofax VRS or PaperStreamIP. The goal is to minimise scanner operator's interventions, but still getting the best images possible. Usually the scanner delivers raw image to driver and/or IP software which performs a variety of actions on the raw image to get best image quality on output.
Functions that are desired are: automatic document size detection and cropping, automatic brightness and contrast adaptation, document alignment, border removal, noise removal, streaks removal, notch filling, automatic removal of blank pages, text readability enhancements like character augmentation, dropout colour setting, background filtering to white or white colour follower adaptation.

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