ref.
ref.book Page 2 Monday, September 28, 1998 4:24 PM Copyright Notice All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SEIKO EPSON CORPORATION. The information contained herein is designed only for use with this EPSON scanner. EPSON is not responsible for any use of this information as applied to other scanners.
ref.book Page 3 Monday, September 28, 1998 4:24 PM Trademarks EPSON is a registered trademark of SEIKO EPSON CORPORATION. EPSON SoundAdvice is a service mark, and Perfection, Micro Step and EPSON FaxAdvice are trademarks of Epson America, Inc. General Notice: Other product names used herein are for identification purposes only and may be trademarks of their respective owners. EPSON disclaims any and all rights in those marks. Copyright © 1998 by Epson America, Inc.
ref.
ref.
ref.
ref.book Page 7 Monday, September 28, 1998 4:24 PM Introduction About Your Documentation This manual includes information on the following: Understanding SCSI Connections explains what daisy chains, SCSI IDs, and terminators are. Upgrading from Windows 95 to Windows 98 explains how to uninstall and re-install the scanner software. Installing the Optional Equipment gives installation and use instructions for the optional transparency unit and auto document feeder.
ref.book Page 8 Monday, September 28, 1998 4:24 PM Using Links Green, underlined text indicates that the text is a link (cross-reference) to other parts of this guide. Click on the text with the mouse pointer to view the referenced information. Cautions, Notes, and Tips Please follow these guidelines as you read your documentation: Cautions must be observed to avoid damage to your equipment. Notes contain important information about your scanner. Tips contain additional hints for better scanning.
ref.book Page 9 Monday, September 28, 1998 4:24 PM Understanding SCSI Connections Read the following sections to determine how to set up your SCSI devices and whether you need any optional SCSI cables. SCSI chain The SCSI interface allows you to connect up to seven devices (such as a scanner, hard disk, CD-ROM, and so on) to the computer. This arrangement is often called a “daisy chain.
ref.book Page 10 Monday, September 28, 1998 4:24 PM SCSI cables If you are using a SCSI cable other than the one provided, the length of the cable must not exceed 9.8 feet (3 meters) to maintain compliance with SCSI-2. If you are connecting multiple SCSI devices to your computer, you may need to purchase SCSI cables before setting up your SCSI chain. Be sure the SCSI cable connectors are suitable for your hardware, depending on the maker of your SCSI device and SCSI interface board.
ref.book Page 11 Monday, September 28, 1998 4:24 PM SCSI termination The first device and the last device in the chain (not including the adapter) must have a terminator. No other device can have a terminator, or if a terminator does exist, it must be turned off or removed. The EPSON Perfection 636 terminator is located at the rear of the scanner. The default position of the termination switch is ON. Do not use an external terminator with the EPSON Perfection 636.
ref.book Page 12 Monday, September 28, 1998 4:24 PM Setting the SCSI ID Number Make sure the scanner is turned off before changing the SCSI ID number. 1 Turn the scanner off. 2 Change the SCSI ID number. 3 Turn the scanner back on. 4 Restart your computer. SCSI ID 2 12 3 45 90 Do not set the SCSI ID to an ID number that is already assigned to another device otherwise the computer, scanner, and other devices will not operate properly. The scanner’s default SCSI ID number is 2.
ref.book Page 13 Monday, September 28, 1998 4:24 PM Changing the SCSI ID Number ID Availability 0 Not available for Macintosh®; used for hard disk Not recommended for Windows®; usually used for hard disk 1 Not recommended; usually used for hard disk 2 Factory setting of the scanner; can be changed 3 Available for Windows.
ref.book Page 14 Monday, September 28, 1998 4:24 PM Changing the SCSI ID Number in Windows 98 If you are using your scanner with Windows 98 and you want to change the scanner’s SCSI ID number, follow the steps below. 1 Double-click the Panel. Scanners and Cameras icon in the Control 2 Select your scanner in the installed devices list, then click Remove. 3 Click OK and close the dialog box. 4 Shut down Windows 98 and turn off your PC and scanner. 5 Change the SCSI ID number of the scanner.
ref.book Page 15 Monday, September 28, 1998 4:24 PM Upgrading from Windows 95 to Windows 98 If you installed the scanner software on a computer with Windows 95 and then upgraded to Windows 98, you must uninstall and re-install the scanner software. Follow these steps: 1 Click the EPSON Scanner Monitor icon in the task bar and select Close to close EPSON Scanner Monitor. 2 Click Start, Settings, and then select Control Panel.
ref.book Page 16 Monday, September 28, 1998 4:24 PM 3 Double-click Add/Remove Programs. Select EPSON TWAIN and click Add/Remove. Then follow the instructions on the screen. 4 To re-install the EPSON scanner software: a Insert your scanner CD-ROM in your CD-ROM drive. The CD-ROM automatically opens to the Main Menu. If it doesn’t, click Start, select Run, and type D:\epson, where D is your CD-ROM drive letter. b Select Re-install Scanner Software. c At the next screen, click Re-install.
ref.book Page 17 Monday, September 28, 1998 4:24 PM Installing the Optional Equipment This chapter includes information on installing and using the two options for the EPSON Perfection 636: ◗ Transparency Unit (B813132) ◗ Auto Document Feeder (B813142) You can purchase these options from EPSON Accessories at (800) 873-7766 (U.S. sales only). In Canada, please call (800) 873-7766 for dealer referral. Or visit our web site at www.epsonsupplies.com (U.S. sales only).
ref.book Page 18 Monday, September 28, 1998 4:24 PM Transparency Unit The transparency unit (B813132) lets you scan negative or positive film strips and slides on your scanner. The transparency unit is compact so it can be attached or removed easily when you alternate between scanning transparent materials and normal reflective (paper) documents.
ref.book Page 19 Monday, September 28, 1998 4:24 PM Unpacking the Transparency Unit Make sure that all the following items are included in the transparency unit box. If any items are missing or damaged, contact your EPSON dealer immediately. Keep all the packing materials so you can use them for storage when you are not scanning transparencies. transparency unit film holders Installing the Transparency Unit Follow the steps below to install the transparency unit on the scanner.
ref.book Page 20 Monday, September 28, 1998 4:24 PM 3 Make sure the document table glass is clean and dust free. 4 Place the transparency unit on the document table glass so that the hinges face the rear of the scanner and it fits on the document table glass: 5 Connect the transparency unit connector (arrow faces up) to the scanner’s option interface: 6 Turn on the scanner. 7 Turn on the transparency unit: 8 See the next section for information on loading transparencies.
ref.book Page 21 Monday, September 28, 1998 4:24 PM Loading Transparencies Before scanning transparencies, wipe the lid of the transparency unit, the scanner’s document table glass, and the narrow window near the hinges. Be sure to keep the window uncovered when loading your transparencies. If your transparency obstructs the window, the colors in your scans will be affected.
ref.book Page 22 Monday, September 28, 1998 4:24 PM Using Film Holders Three film holders are included with this unit. To place film in the holders, see the instructions below. Hold the film by the edges or use gloves. Touching the film surface with bare hands can leave fingerprints or other marks on the film. ◗ Placing the Film ◗ Loading 35 mm Negative or Positive Film ◗ Loading Brownie Size Film ◗ Loading 4 x 5 inch Film To remove a film holder from the document table, lift it out by its tab.
ref.book Page 23 Monday, September 28, 1998 4:24 PM Loading 35 mm Negative or Positive Film Insert a strip of film in the 35 mm film holder, base side facing down. v Then place the film holder on the document table. Be sure to align the upper left corner of the film holder with the upper left corner of the transparency unit. The base side of the film is the side on which the film maker’s name and film ID numbers are printed.
ref.book Page 24 Monday, September 28, 1998 4:24 PM You can adjust the position of 35 mm film by sliding the strips in the film holder so the frames you want to scan are positioned in the window.
ref.book Page 25 Monday, September 28, 1998 4:24 PM Loading Brownie Size Film Insert film in the Brownie size film holder, base side facing down. Brownie size film is 2.4 × 3.5 inches (6 cm × 9 cm). Then place the film holder on the document table. Be sure to align the upper left corner of the film holder with the upper left corner of the transparency unit.
ref.book Page 26 Monday, September 28, 1998 4:24 PM Loading 4 x 5 inch Film Insert film in the 4 × 5 inch film holder, base side facing down. Then place the film holder on the document table. Be sure to align the upper left corner of the film holder with the upper left corner of the transparency unit.
ref.book Page 27 Monday, September 28, 1998 4:24 PM Loading Slides and Film Directly on the Document Table Hold the film by the edges or use gloves. Touching the film surface with bare hands can leave fingerprints or other marks on the film. You can scan slides and film strips in the 4 × 5-inch (101.6 × 127 mm) scanning area of the transparency unit. You can use film holders (as described in the previous sections) or place them directly on the document table.
ref.book Page 28 Monday, September 28, 1998 4:24 PM 2 Load the slide or film with the base side down on the scanner’s document table in the window of the transparency unit as shown: 3 Close the transparency unit. Leave the narrow window uncovered, otherwise the colors in your scans will be affected. window Make sure the unit is completely closed, otherwise an option error results and you will not be able to scan the document or get correctly colored images.
ref.book Page 29 Monday, September 28, 1998 4:24 PM Selecting Settings If you are using EPSON TWAIN, select TPU - Neg. Film or TPU - Pos. Film in the Document Source settings, depending on the type of film (35 mm film strips or slides) you are scanning. When previewing images of negatives scanned using a film holder, the color may appear odd as the frame of the film holder is perceived as white, causing your scans to appear darker.
ref.book Page 30 Monday, September 28, 1998 4:24 PM When scanning thin documents, you may see an impression of the underside of the transparency unit in your scans. If so, remove the transparency unit and re-install the document cover as described in the next section. If you don’t plan to scan transparencies for a while, you can remove the transparency unit and re-install the document cover as described in the next section.
ref.book Page 31 Monday, September 28, 1998 4:24 PM Auto Document Feeder When using the auto document feeder, you must select EPSON TWAIN 3 as your TWAIN source and Auto Document Feeder (ADF) as your Document Source in TWAIN. See your electronic EPSON TWAIN User’s Guide for more information. The auto document feeder (B813142) allows you to automatically load single-sided, multiple-page documents into your scanner.
ref.book Page 32 Monday, September 28, 1998 4:24 PM Installing the Auto Document Feeder Follow the steps below to install the auto document feeder (ADF) on your scanner. 1 Make sure your scanner is turned off. 2 Remove your scanner’s document cover by lifting the back straight up. 3 Make sure the document table is clean and dust free. 4 Remove the protective materials from the ADF.
ref.book Page 33 Monday, September 28, 1998 4:24 PM 5 Insert the hinges on the ADF into the outer square holes at the back of the scanner and close the ADF.
ref.book Page 34 Monday, September 28, 1998 4:24 PM 6 Attach the ADF’s connector to the scanner’s option interface. 7 Attach the paper support to the ADF, as shown. 8 Turn on the scanner. 9 See the following section for instructions on loading paper in the ADF.
ref.book Page 35 Monday, September 28, 1998 4:24 PM Loading Paper into the Auto Document Feeder Your auto document feeder can automatically load up to 20 sheets of the following paper sizes (based on a paper weight of 17 lbs and a stack thickness of 0.16 inch [4.0 mm] or less): Do not feed photographic sheets or valuable original artwork into the auto document feeder as a misfeed may result in accidental wrinkling or damage.
ref.book Page 36 Monday, September 28, 1998 4:24 PM Follow the steps below to load paper into the auto document feeder (ADF): 1 Slide the right edge guide all the way to the right. Make sure no documents or dust are on the document table glass when using the auto document feeder. Dust on the document table glass near the carriage home position may result in vertical lines on the scanned images. 2 Insert the paper stack into the ADF until it meets resistance.
ref.book Page 37 Monday, September 28, 1998 4:24 PM Loading Documents Manually You can load documents manually even when the auto document feeder (ADF) is installed. Opening the auto document feeder or its cover while it is operating results in an option error and paper feeding stops. When scanning thin documents, you may see an impression of the underside of the auto document feeder in your scans.
ref.book Page 38 Monday, September 28, 1998 4:24 PM Clearing Jammed Paper from the Auto Document Feeder To clear jammed paper in the optional auto document feeder, follow the steps below: 1 Turn off the scanner. 2 Push down the release lever to slightly raise the feeder mechanism and release the paper.
ref.book Page 39 Monday, September 28, 1998 4:24 PM 3 Then slowly pull the jammed paper out of the feeder mechanism. (Be careful not to pull too hard; the paper may tear, making it more difficult to remove.) 4 If paper is still jammed inside the mechanism, open the cover to remove it. ADF cover 5 After removing jammed paper, make sure that the cover is closed, and push the feeder mechanism down until it clicks into place.
ref.book Page 40 Monday, September 28, 1998 4:24 PM Removing the Document Cover If you’re scanning something that doesn’t fit under the document cover, you can remove it. To do this, simply lift the back of the document cover straight up. When scanning with the cover removed, make sure you cover any exposed areas of the document table glass to prevent interference from external light.
ref.book Page 41 Monday, September 28, 1998 4:24 PM Maintaining the Scanner Be careful not to scratch or damage the document table glass, and don’t use a hard or abrasive brush to clean it. A damaged glass surface can decrease scanning quality. Never use alcohol, thinner, or corrosive solvent to clean the scanner. These chemicals can damage the scanner components and the case. Cleaning the Scanner To keep your scanner operating at its best, you should clean it periodically.
ref.book Page 42 Monday, September 28, 1998 4:24 PM Replacing the Fluorescent Lamp Never open the scanner case. If you think repairs or adjustments are necessary, consult your dealer. The luminosity of the fluorescent lamp declines over time. If the lamp breaks or becomes too dim to operate normally, the scanner stops working and the operate light rapidly flashes red. If this happens, the lamp assembly must be replaced. For details, contact your dealer.
ref.book Page 43 Monday, September 28, 1998 4:24 PM Removing the Paper Path Guide 1 Turn off the scanner. 2 Disconnect the cable for the auto document feeder (ADF), and remove the ADF.
ref.book Page 44 Monday, September 28, 1998 4:24 PM 3 Gently pull out the paper support. 4 Place the ADF on the document table upside down, with the front of the ADF towards you. 5 Gently pull the two white hooks up, and then push them back down out of the rectangular holes.
ref.book Page 45 Monday, September 28, 1998 4:24 PM 6 Pull the paper path guide upwards and out to remove it. To clean the paper path guide, see Cleaning the Paper Path Guide. To reattach the paper path guide, see Attaching the Paper Path Guide. Be careful not to scratch or damage the paper path guide. Cleaning the Paper Path Guide Use a soft dry cloth to gently wipe the transparent plastic sheet of the paper path guide.
ref.book Page 46 Monday, September 28, 1998 4:24 PM Attaching the Paper Path Guide 1 Insert the transparent plastic sheet of the paper path guide into the paper path of the auto document feeder. 2 Insert the hooks into the rectangular holes in the bottom of the auto document feeder. Make sure the hooks click into place.
ref.book Page 47 Monday, September 28, 1998 4:24 PM Transporting the Scanner If you are transporting the scanner a significant distance or storing it for an extended period, follow the steps below to secure the carriage. If the carriage does not automatically return to the home position, raise the front of the scanner and hold it up until the carriage comes to rest in the home position. Then turn the transportation lock to the locked position.
ref.book Page 48 Monday, September 28, 1998 4:24 PM Troubleshooting This chapter gives you the basics for diagnosing and solving scanner problems. For additional troubleshooting tips, see the “Problems? Need Help?” chapter of your Scanner Basics book and the “Troubleshooting” chapters of your electronic EPSON TWAIN User’s Guide and LaserSoft for EPSON Perfection 636 User’s Guide. First see Problems and Solutions.
ref.book Page 49 Monday, September 28, 1998 4:24 PM Scanner Light The operate light indicates the status of the scanner. If an error occurs, the scanner stops operating and the operate light shows the type of error. Light status Scanner status Solution F (slowly flashing green) Initializing or busy scanning — N (green) Ready to scan images — O The scanner is turned off — F The interface setup is wrong, or (rapidly flashing the scanner is not properly red) connected to the computer.
ref.book Page 50 Monday, September 28, 1998 4:24 PM Operating Problems Problems you may have while using the scanner often involve the operation of your software and computer. Operation problems usually occur because of: ◗ Incorrect setup of the interface card (see Scanner Basics). ◗ Incorrect setup of your computer or software (see Scanner Basics). ◗ Incorrect operation of your software (see your electronic EPSON TWAIN User’s Guide and LaserSoft for EPSON Perfection 636 User’s Guide).
ref.book Page 51 Monday, September 28, 1998 4:24 PM The scanner does not start scanning. Problem Solution The scanner is not turned on. Press the P operate button to turn on the scanner. The interface board is not correctly installed. Make sure that you have selected the correct interface port and settings with your software. Also make sure the interface board in your computer is properly installed. Make sure that the terminator and SCSI ID are correctly set up.
ref.book Page 52 Monday, September 28, 1998 4:24 PM Problem Solution Your system does not meet the minimum system requirements. Make sure that your computer system meets the minimum system requirements, such as the operating system version, specified for your software. You are trying to scan an image at too high a resolution. Confirm that the computer has enough memory for your software.
ref.book Page 53 Monday, September 28, 1998 4:24 PM Part of the image is distorted or blurred. Problem Solution Your document is not flat. Make sure your document is in good condition. Part of the document may be wrinkled, warped, or not in contact with the document table. Be sure the document is uniformly flat. Edges of the document are not scanned. Problem Solution Your document is too large. The document table has non-readable areas around the edges.
ref.book Page 54 Monday, September 28, 1998 4:24 PM The image is faint or out of focus. Problem Solution Your document is not flat. Check that the document is placed flush against the document table. Your software settings are not correct for your document type. See your electronic EPSON TWAIN User’s Guide and LaserSoft for EPSON Perfection 636 User’s Guide for information on software settings. The image is too dark. Problem Solution Your software settings are not correct for your document type.
ref.book Page 55 Monday, September 28, 1998 4:24 PM The image does not look the same as the original. Problem Solution Your software settings are not correct for your document type. Try different combinations of image settings using your scanner software. The colors displayed on your monitor don’t match the original or printed colors. Try increasing your monitor’s color palette to 16 bit or 24 bit.
ref.book Page 56 Monday, September 28, 1998 4:24 PM A line of dots always appears in the scanned image. Problem Solution Your scanner needs cleaning. If this happens on both your screen and printout, the document table glass may be dusty or scratched. Clean the document table glass as described in Cleaning the Scanner. If you are using the auto document feeder, the paper path guide of the auto document feeder may be dusty. Clean the paper path guide as described in Cleaning the Paper Path Guide.
ref.book Page 57 Monday, September 28, 1998 4:24 PM Colors on your monitor are different from those in the original image. Problem Solution The colors displayed on your monitor don’t match the original or printed colors. Try increasing your monitor’s color palette to 16 bit or 24 bit. Because your monitor and printer use different technologies to represent colors, your printed colors cannot exactly match the colors you see on your monitor screen.
ref.book Page 58 Monday, September 28, 1998 4:24 PM The printed image is larger or smaller than the original size. Problem Solution You have changed the resolution or scaled your image. The image size settings in your software determine the size of the printed image. Do not use the size of the image on your monitor to judge the printed size. Your image cannot be printed or the printout is garbled. Problem Solution Your image file size is too large.
ref.book Page 59 Monday, September 28, 1998 4:24 PM Color of negative film preview images looks odd. Problem Solution You are not using the software settings. Check that settings are correct. See your electronic LaserSoft for EPSON Perfection 636 User’s Guide or EPSON TWAIN User’s Guide for details. Make sure the narrow window at the top of the transparency unit is not covered.
ref.book Page 60 Monday, September 28, 1998 4:24 PM Where to Get Help EPSON provides technical assistance through electronic support services and automated telephone services 24 hours a day. The following tables list the contact information: Electronic support services Troubleshooting Service Access World Wide Web From the Internet, you can reach EPSON’s Home Page at http://www.epson.com.
ref.book Page 61 Monday, September 28, 1998 4:24 PM Automated telephone services If you need help using another manufacturer’s software with an EPSON product, see the documentation for that software for technical support information. Service Access EPSON SoundAdviceSM For pre-recorded answers to commonly asked questions about EPSON products 24 hours a day, seven days a week, call (800) 922-8911. EPSON FaxAdviceTM Access EPSON’s technical information library by calling (800) 922-8911.
ref.book Page 62 Monday, September 28, 1998 4:24 PM Specifications This chapter contains specifications for the scanner and options: Specifications are subject to change without notice.
ref.book Page 63 Monday, September 28, 1998 4:24 PM Maximum hardware resolution* 600 dpi (main scan) 2400 (sub scan) Maximum interpolated resolution 9600 dpi Speed (600 dpi, draft mode) Color: 8.1 msec/line Monochrome (bi-level): 2.
ref.
ref.book Page 65 Monday, September 28, 1998 4:24 PM Electrical Specification 100−120 V model 220−240 V model Input voltage range AC 90 to 132 V AC 198 to 264 V Rated frequency 50 to 60 Hz Input frequency 49.5 to 60.5 Hz Rated current 0.5 A Power consumption Approx. 20W 0.3 A Check the label on the back of the scanner for voltage information.
ref.book Page 66 Monday, September 28, 1998 4:24 PM 230V model Safety standards EN 60950 EMC EN 55022 (CISPR Pub 22) class B AS/NZS 3548 class B CE marking 230 V model Low Voltage Directive 73/23/EECEN 60950 EMC Directive 89/336/EECEN 55022 Class B EN 61000-3-2 EN 61000-3-3 EN 50082-1 IEC 801-2 IEC 801-3 IEC 801-4 SCSI Interface Interface type ANSI X3T9.
ref.book Page 67 Monday, September 28, 1998 4:24 PM MESSAGE phase MESSAGE IN phase MESSAGE OUT phase ATTENTION condition RESET condition Logic level TTL compatible Electrical standard ANSI X3T9.
ref.book Page 68 Monday, September 28, 1998 4:24 PM Transparency Unit Specifications Basic Specifications Dimensions Width: 8.8 inches (222.4 mm) Depth: 12.0 inches (305.4 mm) Height: 1.4 inches (36.9 mm) Weight 1.5 lb (0.7 kg) Maximum readable area 3.6 inches × 4.6 inches (93 × 118 mm, size of 4 × 5 film holder opening) Electrical Supply voltage: DC 24V 10%V Rated current: 0.
ref.book Page 69 Monday, September 28, 1998 4:24 PM EMC FCC Part 15 subpart B class B CSA C108.
ref.book Page 70 Monday, September 28, 1998 4:24 PM Auto Document Feeder Specifications Basic Specifications Dimensions Width: 12.6 inches (319 mm) Depth: 17.8 (451 mm) Height: 5.4 inches (137 mm) Weight 4.9 lbs (2.
ref.book Page 71 Monday, September 28, 1998 4:24 PM Safety approvals UL 1950 CSA C22.2 No. 950 EN60950 (VDE) IEC950 (ROSTEST, PSB) EMC FCC Part 15 Subpart B Class B CSA C108.
ref.book Page 72 Monday, September 28, 1998 4:24 PM Paper quality High-quality bond paper, check paper, recycled paper Applied color Color and monochrome Document type Documents printed with impact printers, laser printers, or facsimile machines Don’t use the following paper types: transparencies, coated paper, labels, carbon paper, or paper with staples, holes, rips, curls, or folds.
ref.book Page 73 Monday, September 28, 1998 4:24 PM Glossary additive primary colors The colors of red, green and blue (RGB) —which give the perception of white when fully added. These are the colors of the color system used with monitors and scanners. bit Short for binary digit. The smallest unit of data in computer processing. A bit can represent two values: on and off, or 1 and 0. bit/pixel The unit that indicates the number of bits allocated for a pixel.
ref.book Page 74 Monday, September 28, 1998 4:24 PM default dithering document dpi A set of values used when no other selections have been made. These are sometimes called factory defaults if the original values have not been changed since the scanner has left the factory. A process in which software or an output device simulates continuous tones with groups of dots. The item, such as a sheet of paper or a book, that is placed on the document table for the scanner to read. Dots per inch.
ref.book Page 75 Monday, September 28, 1998 4:24 PM OCR Optical Character Recognition. The technology that allows computers to “read” text from physical objects. OCR requires a graphical representation of text to interpret, which usually comes from a scanned image. page sequence The type of color scanning in which the entire image is scanned once for each separate color. pixel Short for picture element. Each image is composed of a number of pixels. Pixels are also counted in units of dots.
ref.book Page 76 Monday, September 28, 1998 4:24 PM subtractive primary colors terminator Glossary The colors cyan, magenta, and yellow (CMY)— which produce black when mixed in certain amounts. In printing, black is often added to give more definition as mixing of actual inks cannot produce pure black. A device that stops electronic signals, and prevents them from proceeding or returning to other devices. This is necessary to stop a signal from continuously bouncing between devices.
ref.
ref.
ref.
