Flatbed Input DevicesIntroductionFlatbed input devices are basically scanners which scan a document which is put on the machine and generates an image of the document in an image editor. The difference between a copy machine and Flatbed input device is that a copy machine prints a physical copy whereas the flatbed input device generates a digital image. Using a flatbed scanner, you can scan a wide-range of documents, papers as well as 3-D objects.WorkingTwain Software: This is the software used to operate the flatbed input devices. There are many softwares, however this software was decided upon by the flatbed input device companies to be used so that all images produced have a common origin and hence same property. The Twain Software contains a Twain driver which is another program which transfers the image generated into the image program memory. The driver has various different functions, such as setting the resolution, area of flatbed to be scanned, colour tones, etc. This software is also responsible for re-arranging the data received from logic board i.e, a group of pixels, into an actual picture.Logic Board: The logic board sends instructions to the scanning unit such as setting how far the motor will run and how fast, where to start scanning, etc. The board also receives data from the CCD sensors that return the data of scanned image.CCD Sensors: The CCD sensors i.e, Charged-Coupled Device sensor senses the amount of light (provided by scanner) reflected from the document and accordingly changes the light to an analog voltage signal which is changed into a digital signal using an ADC device. This data is then sent to the logic board which is ultimately transmitted back to the computer. Pros and Cons of Flatbed ScannersPros:Easy to use.Provides excellent quality digital image.Cons:These are large and bulky devices compared to other scanners.These type of scanners are costly.Types of ScannersCCD Scanner: These flatbed CCD scanners emit a cold cathode light, which is collected in the light sensor of the scanner using various mirrors and lens. AdvantagesThere is high signal ratio due to light source being a fluorescent lamp.Due to presence of apochromatic lenses (lens having better correction of chromatic and spherical aberration), there is a greater focus depth. DisadvantagesThese scanners are expensive.These scanners are more complex and fragile.Lens distortion could affect image obtained.CIS Scanner: Here, the system of CCD devices as well as mirrors are not used. Instead, LED devices are used of red, green and blue. A lens collects the reflected light from the document and focuses the light on a light sensor. Different aspects of the document are determined from the intensity of light received by the sensor. AdvantagesCheapCompactMore PreciseMore DurableHigher Optical resolutionNo lens distortion DisadvantagesSensitive to focus depthLower signal ratio due to LED sourceHand Scanner: These are popular devices which are much more compact than flatbed scanners and are portable as well. These scanners are mainly used when flatbed scanners cannot be used because the object to be scanned cannot be put on the scanner. This scanner must be held above the object correctly without movement so as to minimize distortion.Smartphone Scanner:There are many applications which use our phone’s camera and flashlight to scan an image and produce a digital image on our phone’s screen which can be edited.TroubleShootingIf a flatbed scanner fails for any reason, these are some methods to troubleshoot the problem:Ensure wires are properly connected.Verify scanner is getting power.Try restarting all devices involved in scanning.Try disconnecting other devices and check if scanner is working. If this is the case, then the device disconnected is faulty.Regularly update driver softwares to ensure any software bugs be fixed.TroubleShooting when using AcrobatIf you are using Acrobat for scanning, try using WIA (Windows Image Acquisition).Restart your computer after disabling applications other than Acrobat as these applications may interfere with performance of Acrobat and may cause it to hang.Rescan the image using different colour mode.Specify image size during scanning document.Log in with new account.

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