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Basic copier for Service Master
Basic copier for Service Master
Last Modified: 10/07/2001
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Basic copier for Service Master
Short Description
This basic copier module is the starting point for a new employee, to start his career as a service technician. The module contains the basic technologies that used in the copy process for analog and digital copiers.
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Objectives
After com pletion of this training a serv ice technician: Is familiar with the user feature s of a copier Understand the copiers jargon/terminology Ha s a good understanding about the basic technologies of a copier Can do installation, including options can print a SMC sheet can determine the firmware version can do a firmware upgrade Can do maintenance Can do troubleshooting Can do adjustments Can report to the product specialist Knows how to u se a Service Manual Can follow product training for engines
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Course Overview
1. Copy paper 2. Copier 3. User Training 4. Options / Installation 5. Advanced copier technology 6. Service 7. Information Flow 8. Specifications
This training module tells about the copy process. First, it is important to know what a user can do with a copier. After this, the module gives an answer on what happens inside that copy machine. From scanning the original, it says how the toner particles come onto the right location on the copy and why the toner sticks to the paper. What is the difference between an analog and a digital copier? It also describes the paper path trough the machine. Besides knowing how the copier works, the engineer must know what to do at the customers. With help of some tools and manuals, he must be able to keep the copier running, with good copy quality. Copiers need maintenance after a periodic number of copies, just like cars after some kilometers. If the copy quality is bad, you might adjust the machine. If the machine is broken, you might repair it.
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Requirements
Computer based training: Windows PC Or Macintosh Hands on: Digital black and white copier, ADF/ARDF, Finisher Training materials
Computer based training: Windows PC: Intel 486 processor, minimum 66 MHz (Intel Pentium-processor recommended) Windows 95/98/NT Double-speed CD ROM or better Minimum 16 Mb of free RAM Color display recommended Soundcard recommended Macintosh: Power Macintosh recommended Mac OS 7.6 or higher (previous Mac OS needs the thread manager) Double speed CD ROM or better Minimum 16 Mb of free RAM Color display recommended Hands on: Later in this training module we need this requirements to do some exercises. The exercises in this module are generated for a generic copier with ADF and finisher. However it is possible that not all exercises can be done on all machine's, because some functions are not available, in that case skip that part of the exercise.
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Pre-requisites
Basic electronic skills
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Training Materials
Main Document Maincopier.ppt Downloads Basiccopier.exe CBT Operating Instructions
Main Document Maincopier.ppt ¾ PowerPoint presentation with notes pages of the main document Downloads Basiccopier.exe ¾ Self extractable pdf file containing: main document notes pages core technology manual pages for basic copier Exercises CBT Copier technology Technical Training Tool (Basic copier CBT)
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Exam
Yes, WICE Multiple choice exam
Name of the exam: Basic copier exam
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1. Copy paper
Study the Copy Pa per section of the Copier Computer Based Traini ng CD.
1. Copy Pap er
Study the Copy Paper section of the Copier Computer Based Training CD. Make sure that you understand: Paper sizes Paper weight Paper gain Paper curl Front and back sides of paper
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2. Copier
Study the Copier section of the Copier Computer Based Training CD.
2. Copier
Study the Copier section of the Copier Computer Based Training CD. Make sure that you first have to start with the analogue copier and that you understand: Copy process overview A closer look ¾ Scanning Scanning Absorbing Exposure to photoconductor Lens Enlargement Reduction ¾ Photoconductor Types Layers ¾ Toner on latent image Charge Exposure Development Transfer Separation Cleaning Quenching ¾ Transfer to paper Friction FRR Registration ¾ Fusing
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After you finished the analogue copier continue with the digital copier and make sure that you understand: Scanning Shading ¾ White shading ¾ Black level correction Laser exposure Development
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3. User Training
3. Use r Training
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User Training Content
Introduction Operation panel User tools Basic functions Other functions
3. Use r Training
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Introduction
All functions and features on copiers can be used to change the output For example the original's are simplex but the output is duplex with a staple.
3. Use r Training
This part of the module will explain most common used functions and features on copiers.
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Different Levels
Normal User tools Service mode
3. Use r Training
Normal Every user can use the machine for copying User tools In the user tools items can be changed for example date and time. In the user tools there is a special function called key operator tools, this is a kind of administration tool. A password can be programmed that not all users can access the key operator user tools. Service mode The service mode is for the technician.
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Scanning
The original can be placed on the platen glass or ADF (automatic document feeder) With an ARDF (automatic reverse document feeder) scanning can be done on both side's of the original
3. Use r Training
The ADF can hold a lot of documents to scan it all together. The number of documents that can be put in the ADF depends on the copier model.
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Imaging
The image process can be changed Image density Enlarge / reduce Photo mode / text mode Positive / negative Image repeat (more image's on one sheet) Poster mode
3. Use r Training
After the scanning process the images are stored in memory and can be processed with the settings (see above) selected by the user. All these processes are done on a digital way.
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Paper Selection
Input selection Paper size Which tray Orientation Output selection Which output bin
3. Use r Training
Paper size On the operation panel you can be defined which paper tray will be used for the copy job. If a paper tray is filled with A3 sized paper and an other tray is filled with A4 sized paper, we can make a selection which paper size can be used. Which tray All tray's can be selected. In case of thick paper or an other size the bypass tray can be used. The bypass is not meant for large amount of paper. Orientation The A4 size paper can be stored in 2 way's LEF (long edge feed) and SEF (short edge feed). If the paper tray's are filled with A4 LEF and with A4 SEF, the selection for orientation can be made. Output selection If there are more output bins there can be a selection for which one.
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Function Select
Number of copies Simplex / Duplex Booklet / Magazine
Simplex
Duplex
Booklet/Magazine
3. Use r Training
When starting a copy job we can select the number of copies. Simplex or duplex is done by putting the right image on the front side or the front and back side of the paper. Booklet or magazine is a combination of 4 images on one sheet of paper.
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Finisher options
Punch Staple Sort Stack Staple Punch
1 2 3 1 2 3 1 2 3
Sorting
3. Use r Training
stacking
To select punch or staple the option should be installed in the finisher. Sort Sorting will create a number of sets start from the first to the last page on the same way as your originals. When staple is selected sort is also selected automatically. Stack Stacking will make it easier to separate the copied sets.
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Key Layout
Example of a n opera tion panel. Each button w ill be explained at the follow ing slides
3. Use r Training
Each model has it's own operation panel layout however the symbols that are used are the same. The way of selecting a function can be different, in that case see your operating instruction for your machine.
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Screen Contrast
Screen adj ust knob
3. Use r Training
To adjust the screen for a good clear view turn this knob.
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Indicators
Indicators show s errors or s tatus
3. Use r Training
These indicators can be different on a other copier models. These indicators will show you the following: (starting from the top left) Staples empty, Toner empty, Paper empty Maintenance needed, cover not closed, Paper jam Communicating (not used for standard copier) Receiving a file (not used for standard copier)
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User Tools/Counter
User tools / counter key
3. Use r Training
Two functions for this button. To access the user tools and to access the counter (how many copies are made).
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Functions
3. Use r Training
Copy mode Document server mode Facsimile mode Printer mode Scanner mode
At this moment we are only discussing a standard copier. For a lot of copiers there are option's available for example a fax option. By selecting one of these buttons, the selection for that option can be made.
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Display
Used for input and output.
3. Use r Training
This is an example of a display. The display is used for output and input. Input All selection can be made by touching the right items on the screen. Output All information will be displayed, like settings, errors etc.
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More Buttons
Check Modes Program Clear modes
Energy Saver
Interrupt
3. Use r Training
Check Modes Key Press to check the entered copy job settings. Program Key Press to select the program mode. Clear Modes Key Press to clear all selected copy job settings. Energy Saver Key Press to switch to and from Energy Saver Mode. Interrupt Key Press to make interrupt copies during a copy run.
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Power
Main Pow er Indicator On Indicator
Operation Sw itch
3. Use r Training
Main Power Indicator Indicates if the main power is turned on. If a printer or a fax option is installed, the main power should never be switched off. For example the machine Main power switch is off and someone is sending you a fax message, the fax won't be received because the machine is switch off. On Indicator The on indicator will be lit if the machine is switched on for operation. If the indicator is blinking it means that the machine is doing something for example reading/writing the hard disk. If this indicator is blinking never touch the main power switch, because it can damage your machine. Operation switch This switch is used the switch off and on the machine. If the machine is switched off it still can be used for printing and receive fax messages.
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Number Keys
Number ke ys
3. Use r Training
Number Keys With the number keys you can enter the number of copies required. In case of a Multifunctional product they are also used to enter the numbers for faxing.
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Start / Stop / Sample
Sample Copy
Start
Clear / Stop
3. Use r Training
Sample copy button Used to see if the output is correct. If the sample copy is approved the keypad can be used to set the number of copies. Start button Pressing the start button it will start your copy job. Clear / Stop button Clear to delete a entered number Stop to stop a copy process in progress
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Exercise
Do the exercise user functions
3. Use r Training
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User Tools
User Tools special settings can be done. System settings Timer settings Key operator tools Copier settings Density Margin's
3. Use r Training
User tools From the first screen a selection can be made for system settings, copier settings, printer settings, scanner settings and counter. System settings In the system settings a lot of items can be changed that are related to the system for example date and time. The key operator tool can be accessed from the system settings. For example to change user code's. The key operator tool can be password protected. Copier settings All items that are related to the copier process can be changed here. For example density and margin's
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4. Options / Installation
4. Options/Installation
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Options
Examples Finisher Paper bank Duplex unit Interfaces Mailbox Other
4. Options/Installation
Each device can have options installed. Details about what options can be installed and it's functions are explained in the Operating Instructions coming with the device. Setup Guide Provides information about setting up the device and its options. This manual is provided as a printed manual, and also as a PDF file on the CD-ROM labelled "Operating Instructions".
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Installation
The installation procedure is described in the Service Manual
4. Options/Installation
Requirements The installation chapter starts with requirements like: Environment Machine level Minimum space Power Options In case of installing options there could be a logical order. Some times you will find a installation flow chart for this order.
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5. Advanced Copier Technology
5. Advan ced Copie r Te chnology
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Core Technology Manual
Core Tec hnology Manual topics Serv ice Manual CD's
5. Advan ced Copie r Te chnology
For several topics in this advanced copier technology chapter there will be referred to the Core Technology Manual (CTM). The CTM can be found on the Service Manual CD ROM's.
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Advanced copier technology content
5.1 Handling paper 5.2 Photocopying processes 5.3 Digital processes 5.4 Process control 5.5 Standard Components
5. Advan ced Copie r Te chnology
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5.1 Handling paper
Paper feed Paper feed methods Paper tray By pass Paper size detection Paper end detection Registration Paper transport Duplex Misfeed detection
5.1 Adv anc ed Copier T echnology > Handling Pape r
Study the CTM > Handling paper and make sure that you understand: Paper feed Paper feed methods Paper tray By pass Paper size detection Paper end detection Registration Paper transport Duplex Misfeed detection
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Paper feed
Paper feed is the separation of a single sheet of paper from a paper source--usually a stack of paper in a cassette or tray--and moving it into the machine.
5.1 Adv anc ed Copier T echnology > Handling Pape r
CTM > Handling Paper > Paper Feed There are several key factors involved with handling paper in office machines (copiers, printers, faxes, whatever). First, there has to be a stock of paper from which to feed, which implies some kind of holder--a tray, a cassette, or a roll--which positions the paper properly for feeding. Second, there has to be a method of separating a single sheet from the source; this is referred to as paper feed. Finally, most machines use sensors to detect paper size and detect the presence or absence of paper. After paper is fed into a machine, it must be transported to a registration mechanism, then to an imaging section where the image is transferred to the paper. Finally the paper passes through an image fusing section and exits the machine.
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Paper feed methods
Feed and Rev erse Roller (FRR) Friction Pad
Feed roller
Pick-up roller
Reverse roller Feed roller
Friction pad
5.1 Adv anc ed Copier T echnology > Handling Pape r
CTM > Handling Paper > Paper Feed Feed and Reverse Roller (FRR) The FRR feed mechanism consists of a pick-up roller, a feed roller, and a reverse roller. Friction Pad The friction pad mechanism has two principle components--the paper feed roller and a friction pad. CBT reference > Copier > Analogue copier > A closer look > Transfer to paper
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Paper tray
A paper tray is a non-removable drawer or bin that is permanently built into or attached to the machine.
500 _she et_t ray .tif
170 0_sh eet _tr ay.tif
5.1 Adv anc ed Copier T echnology > Handling Pape r
CTM > Handling Paper > Paper Feed Paper Tray A paper tray is a non-removable drawer or bin that is permanently built into or attached to the machine. The capacity of paper trays varies considerably; smaller trays typically hold 250 to 500 sheets of paper, but large capacity trays hold a paper stock of 1000 or more sheets.
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By pass
odd paper sizes stiff feed stock such as post car ds or O HP transpare ncies
5.1 Adv anc ed Copier T echnology > Handling Pape r
CTM > Handling Paper > Paper Feed By-pass Feed Tray Most copiers and multifunction machines incorporate a fold-out by-pass feed table. Bypass feed is useful for casual copying on odd paper sizes. Also, on most machines, the by-pass feed tray provides a straight paper path that is suitable for stiff feed stock such as post cards or OHP transparencies.
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Paper size detection
Sw itch Com bina tion Paper Size Dial
5.1 Adv anc ed Copier T echnology > Handling Pape r
CTM > Handling Paper > Paper Feed For many copy processes, operation timing depends on paper size. Machines can detect paper size in a number of different ways. Here are some common ones. Switch Combination ¾ The illustration at the top right shows a paper size detection mechanism commonly used with cassettes and smaller paper trays. Paper Size Dial ¾ Some paper trays use a dial to change paper size (bottom right).
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Paper end detection
typical paper end detection mecha nism for a small paper tra y
Paper End Feeler Paper End Sensor
Cutout
Lever
5.1 Adv anc ed Copier T echnology > Handling Pape r
CTM > Handling Paper > Paper Feed The illustration to the right shows a typical paper end detection mechanism for a small paper tray. When the paper tray runs out of paper, the paper end feeler drops into the cutout in the tray bottom plate, and the paper end actuator activates the paper end sensor. The paper end actuator is in contact with a lever. When the tray is drawn out, the lever turns as shown by the arrow and pushes up the actuator. As a result, the feeler rotates upwards. This mechanism prevents the feeler from getting damaged by the paper tray body.
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Registration
Registra tion Using A Stopper Registra tion Using Rollers
5.1 Adv anc ed Copier T echnology > Handling Pape r
CTM > Handling Paper > Paper Feed There is often some slippage during paper feed. As a result, paper cannot be transported directly to the image transfer or printing position, because the image position on the paper would not be stable. After paper feed starts, its transport timing requires adjustment to match it with the imaging process timing. This alignment is called "image registration" or just "registration". Generally the registration process also removes any skew that the paper may have acquired during paper feed. Here are some common ones. Registration Using A Stopper ¾ Some machines use a stopper to delay the paper at the registration rollers. It allows a simplified drive mechanism where the registration rollers are not stopped during feeding. This method is used mainly with low speed machines. Registration Using Rollers ¾ Most copiers and printers use registration rollers to match the paper timing to the image and remove skew. CBT reference > Copier > Analogue copier > A closer look > Transfer to paper
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Paper transport
Roller Tra nsport Belt + Vacuum Tra nsport
5.1 Adv anc ed Copier T echnology > Handling Pape r
CTM > Handling Paper > Paper Feed Roller Transport The illustration to the right shows a typical vertical transport mechanism that is used in several models. Belt + Vacuum Transport Many photocopiers use a combination of belts and vacuum fans to transport paper from the drum to the fusing unit. The vacuum holds the paper firmly against the transport belts. This method has the advantage of holding the paper secure to prevent vibrations or slippage that might disturb the as yet unfused toner image.
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Duplex
Single sheet Stack
5.1 Adv anc ed Copier T echnology > Handling Pape r
CTM > Handling Paper > Paper Feed Mechanism in a Photocopier that allows the machine to feed a sheet of paper twice through the machine to enable automatic duplex copying. Duplexing mechanisms can take many forms. However, they have the following things in common. They all have some way of sending copies or prints to the duplex mechanism. This is usually accomplished by a "junction gate", which redirects the paper as it exits from the fusing unit. There is a mechanism that turns the paper over (reverses it) so that it is ready to receive an image on the reverse side. This can occur before the paper enters the duplex tray or after it exits the duplex tray. Duplexing systems in most machines also have the following mechanisms. There is a tray to hold the sheets of paper to be duplexed. Usually, it is simply "called the "duplex tray". There is a mechanism, usually called a jogger, to align the sheets of paper in the duplex tray. There is a paper feed mechanism employing one of the standard paper separation techniques. Conclusion: There is are 2 different duplexing methods. First one is stack, where paper is gathered in a tray and fed back into the machine in reverse position. Second one is single sheet duplex (interleave duplexing), where paper is not gathered but directly reversed in a tray and fed back into the machine. Next slide will give you an example of the interleave duplexing.
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Interleave Duplexing
Memory needed Productiv ity increased Decrease w ear on originals
5.1 Adv anc ed Copier T echnology > Handling Pape r
CTM > Handling Paper > Paper Feed Some digital machines have a lot of RAM and a large capacity hard disk that can store many pages. This allows a different method of Duplexing called "interleave Duplexing", in which sheets are not stacked. Instead, in interleave Duplexing, sheets are continuously fed through the machine and the correct image is selected from memory or disk depending on which sheet and side is in the imaging section. This type of mechanism allows more than one page to be processed at once, and it increases the productivity of duplex imaging, especially when making multiple duplex copies. Also, in the case of making copies from paper originals, it decreases the cycling of and the wear on originals. The example shows a 14-page copy. The large numbers in the illustration show the order of pages. The small numbers in circles show the order of sheets of copy paper (if shaded, this indicates the second side).
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Misfeed detection
photo i nterr upters unaffected by the reflectivity or transpa rency
Phototransistor
LED
Paper
5.1 Adv anc ed Copier T echnology > Handling Pape r
CTM > Handling Paper > Paper Feed Misfeed Detection Office machines that print images on paper (copiers, fax, laser printers, etc.) have to detect paper Misfeed and jams and take appropriate action. One or more sensors placed along the paper path accomplish Misfeed detection. Typically, photo interrupters with feeler actuators are used for Misfeed detection because they are unaffected by the reflectivity or transparency of the feed stock. The number of Misfeed detectors used depends on the length and complexity of the paper path
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5.2 Photocopying processes
Charge Exposure Development Image Transfer And Paper Separation Cleaning Quenching Fusing
5.2 Adv anc ed Copier T echnology > Photocopying Proc es se s
Study the CTM > Photocopying processes and make sure that you understand: Charge Exposure Development Image Transfer And Paper Separation Cleaning Quenching Fusing 1. CBT reference > Copier > Analogue copier > A closer look > Toner on Latent Image 2. CBT reference > Copier > Digital copier
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Overview
1. Char ge 2. Exposure 3. Dev elopment 4. Image Trans fer And Paper Separation 5. Cleaning 6. Quenchi ng 7. Fusing
1 6
2
5 3 7 4
Fusing section
5.2 Adv anc ed Copier T echnology > Photocopying Proc es se s
CTM > Photocopying Processes In this slide you can see an overview of the process around the drum.
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Charge
Cor ona Charge Char ge Roller Method
5.2 Adv anc ed Copier T echnology > Photocopying Proc es se s
CTM > Photocopying Processes > Charge Charge refers to the application of a uniform electrostatic charge to a photoconductor in darkness. At present, two kinds of electrostatic charge methods are widely used. The most common is the corona electrostatic charge method (non-contact type), which takes advantage of the corona discharge produced when a high voltage is applied to a fine wire. The other is the electrostatic charge roller method (contact type), which provides an electrostatic charge by applying a high voltage to a roller and contacting the roller to the photoconductor.
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Exposure
Analog Machines Digital Machines
5.2 Adv anc ed Copier T echnology > Photocopying Proc es se s
CTM > Photocopying Processes > Exposure Exposure refers to a process where light is applied to a photoconductor to create a latent reverse image on in the form of a charge pattern on the surface of the photoconductive material. Depending on the brightness of the image, the electric potential on the photoconductor's surface is attenuated; thus, forming an electrostatic latent image In general you can say that we use three main exposure methods flash exposure strip exposure (sometimes called slit exposure) laser exposure (covered in the Digital Processes chapter) Analog Machines An exposure lamp illuminates the original. Mirrors reflect light from the original directly onto the photoconductor. This light writes a latent image on the photoconductor. This image is then developed with toner and transferred to the copy paper. Digital Machines The big difference with scanners in digital machines is that the light reflected from the original does not pass directly to the photoconductor. The light is reflected onto a light-sensitive element, such as a CCD (Charge Coupled Device). This device converts the light into an analog electrical signal. Circuits inside the machine convert this signal into a digital signal. This signal then passes to a laser diode, which emits a laser beam to write a latent image on the photoconductor. So, in a digital machine, there is a lot of electronics between the light reflected off the original and the light arriving at the photoconductor.
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Development
dual-component development method single-component development method
5.2 Adv anc ed Copier T echnology > Photocopying Proc es se s
CTM > Photocopying Processes > Development Development systems are divided into: dual-component development method single-component development method (mono-component) Dual-component The two-component development process uses developer made of mixed toner and carrier. These two components rub against each other in the development unit and take on opposite charges. The charged latent image areas of the drum attract the charged toner particles. Advantages Achieves high speed development Allows relatively wide scope in terms of accuracy Disadvantages The development section is complex and large Deterioration of developer over time (difficult to achieve maintenance free operations) Requires toner concentration control Mono-component The mono-component development process uses toner only (no carrier). Monocomponent development systems are used mainly in small photocopiers with a low copy rate. Advantages: Development unit structure is simple and compact. Toner density control is unnecessary. Disadvantages: Unsuitable for high speed developing Suitable for low-volume copying only because the development unit parts wear out relatively quickly.
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Image Transfer And Paper Separation
A. Pre-trans fer B. Image Trans fer C. Paper Separation
5.2 Adv anc ed Copier T echnology > Photocopying Proc es se s
CTM > Photocopying Processes > Image Transfer & Paper Separation The transfer and separation process can be broken down into three areas: Pre-transfer Just before the image transfer process starts, guides direct the paper against the photosensitive surface of the drum (or belt). The mechanism is structured so that the transfer charge does not reach this area, and therefore, the paper can achieve complete contact with the photoconductor before image transfer starts. Image Transfer This is the area where the image is actually transferred from the photoconductor to the paper. Generally, an electrostatic charge is applied to the back of the paper to pull the oppositely charged toner from the photoconductor to the paper. Paper Separation The paper separates from the photoconductor after the toner image is transferred. This is usually achieved by applying an ac corona to the back of the paper to eliminate the previously applied transfer charge. Pick-off pawls are also used to physically separate paper of low stiffness from the drum.
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Cleaning
Cleaning blades Cleaning br ushes
Counter Blade
Cleaning Brush
5.2 Adv anc ed Copier T echnology > Photocopying Proc es se s
CTM > Photocopying Processes > Cleaning Cleaning refers to the process of removing any toner remaining on the photoconductor (drum or OPC belt) after the imaging process is complete to prepare the photoconductor for the next copy/print cycle. The cleaning step also removes any paper dust on the photoconductor surface. Cleaning is necessary before a new copy cycle or print cycle can start. If the cleaning step were not included in the copy process, the background of images would become progressively darker and dirtier. All cleaning systems use a cleaning blade or a cleaning brush or both. Additionally, all cleaning systems have a mechanism for collecting and storing (or recycling) the collected toner. The most common cleaning systems use blades, and these are further divided into trailing-blade cleaning and counter-blade cleaning systems. Cleaning brushes all rotate in contact with the photoconductor. There are also two types of cleaning brushes--fiber brushes and magnetic brushes. Some cleaning systems also use a corona (pre-cleaning corona) to prepare the drum and toner for cleaning.
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Quenching
eliminates any residual electric charge remaining on the photoconductor after the cleaning process
5.2 Adv anc ed Copier T echnology > Photocopying Proc es se s
CTM > Photocopying Processes > Quenching Quenching is the process that eliminates any residual electric charge remaining on the photoconductor after the cleaning process. Quenching prepares the photoconductor for the charge step of the next copy or print cycle. Several different methods are used to quench the photoconductor. The most common method is photo quenching using a lamp. Some machines use a combination of a dc corona and photo quenching. A few machines use an ac corona for quenching. The choice of quenching method depends on the type of photoconductor used and the details of the other steps of the copy process.
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Fusing
Hot roller Pressure roller Fusing lamp Stripper paw ls Fusing lamp Hot Roller Press ure Roller
Stripper Pawls
5.2 Adv anc ed Copier T echnology > Photocopying Proc es se s
CTM > Photocopying Processes > Fusing After the image transfer and paper separation steps, the image must be bound or "fixed" to the paper. Modern photocopiers and other machines (fax, printer) that use photocopier imaging processes, use resin based toners. To form a stable permanent image, the toner is heated to cause it to melt and soften. Simultaneously, pressure is applied to cause the toner to fuse with the fibers of the paper.
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5.3 Digital processes
Digital scanning Image processing Scanner gamma correction Photo mode smoothing Moiré Grayscale processing Binary picture processing Image rotation Printing
5.3 Adv anc ed Copier T echnology > Digital Proc es se s
Study the CTM > Digital Processes and make sure that you understand: Digital scanning Image processing ¾ Scanner gamma correction ¾ Photo mode smoothing ¾ Magnification and Reduction ¾ Moiré ¾ Grayscale processing ¾ Binary picture processing ¾ Image rotation Printing CBT reference > Copier > Digital copier
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Digital Scanning
Analog Machines Digital Machines
5.3 Adv anc ed Copier T echnology > Digital Proc es se s
CTM > Digital Processes > Digital Scanning Earlier in this module we already explained the difference between the analog and digital scanner. Analog Machines An exposure lamp illuminates the original. Mirrors reflect light from the original directly onto the photoconductor. This light writes a latent image on the photoconductor. This image is then developed with toner and transferred to the copy paper. Digital Machines The big difference with scanners in digital machines is that the light reflected from the original does not pass directly to the photoconductor. The light is reflected onto a light-sensitive element, such as a CCD (Charge Coupled Device). This device converts the light into an analog electrical signal. Circuits inside the machine convert this signal into a digital signal. This signal then passes to a laser diode, which emits a laser beam to write a latent image on the photoconductor. So, in a digital machine, there is a lot of electronics between the light reflected off the original and the light arriving at the photoconductor.
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Image processing
5.3 Adv anc ed Copier T echnology > Digital Proc es se s
Image processing describes how digital machines convert the image from a scanned original into digital data. Image processing use techniques for processing the digital data, so that the printout is as close to the original as possible. For example, techniques used to process a business letter will be different from those used to process an original containing photographs. Each model implements these techniques in different ways, and some models do not implement all the techniques. The techniques used by black-and-white machines and color machines are different, but these kind of details will be explained in the product trainings. The CTM will explain all of the techniques in detail. For this training module we only discuss some of them.
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Scanner gamma correction
relationshi p be tw een original ima ge density a nd analog circui t output shoul d be linear as show n in the upper diagram. How ev er, in reality, it is more like that s how n in the low er diagram.
5.3 Adv anc ed Copier T echnology > Digital Proc es se s
Scanner Gamma Correction Scanner gamma correction corrects the data to compensate for the characteristics of the scanner (e.g., CCD response, scanner optics). This ensures that the various shades in the gray scale from black to white on the copy match those on the original. The relationship between original image density and analog circuit output should be linear as shown in the upper diagram. However, in reality, it is more like that shown in the lower diagram. Gamma correction corrects the data for this deviation, as shown by the arrows in the lower diagram. In some machines, the gamma curve can be changed with a service mode. Also, some machines automatically adjust the gamma curve depending on the image density setting selected by the user.
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Photo mode smoothing
To make a softer image
Text Mode
Photo Mode
5.3 Adv anc ed Copier T echnology > Digital Proc es se s
Photo mode smoothing There are some different processes that use the name 'smoothing'. Photo mode is to make a softer image. Smoothing smoothes the contrast between adjacent pixels, giving better reproduction for photos. Because of this, it will not normally be used in text mode.
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Moiré
The m oiré pattern typically appears w hen the CCD pixel density is a mul tiple of the density of the regular lines on the ori ginal.
5.3 Adv anc ed Copier T echnology > Digital Proc es se s
Moiré When one pattern is imposed over another sometimes they interfere with each other and form a third pattern called a moiré pattern. In our products, MTF processing is a major cause of moiré patterns. The photos show the result of moiré. The moiré pattern typically appears when the CCD pixel density is a multiple of the density of the regular lines on the original.
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Grayscale processing
Grayscale processing uses many shades for instance 64 or 256.
64 Grays cales
5.3 Adv anc ed Copier T echnology > Digital Proc es se s
256 Grayscal es
Grayscale Processing The human eye can discern up to about 200 different levels, or shades, of gray. A lot of digital copiers can create 256 gray levels: 0 through 255. Compare the right and left halves of the images, to see the difference if you have more grayscales available. Grayscale processing uses many shades of gray to reproduce continuous tone originals, such as those containing photographs. A black and white photograph contains an unlimited number of shades of gray, but digital copiers and printers can normally only output a few shades, normally 64 or 256. If grayscale processing is used, the result is a multi-bit per pixel stream of digital data. For example, if there are 256 shades of gray, there are eight bits per pixel. 00000000 11111111
0 255 Note that grayscale processing needs a lot of memory. At eight bits per pixel (256 shades of gray), an A4 or LT page needs about 14 megabytes, without compression.
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Binary picture processing
One bit output White or Black
5.3 Adv anc ed Copier T echnology > Digital Proc es se s
Binary Picture Processing In binary picture processing, the output data is one-bit only. There are no shades of gray. the output is black or white only. The multi-bit per pixel data stream has to be reduced to single-bit data. To do this, a threshold level is used. If a pixel has a value that is brighter than the threshold, it becomes a white pixel. If it is darker than the threshold, it becomes a black pixel. The threshold can usually be adjusted, and it often varies depending on modes selected at the operation panel. The example on the slide shows how the threshold level affects the output.
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Image rotation
5.3 Adv anc ed Copier T echnology > Digital Proc es se s
Image Rotation If the machine has paper of the same size as the original but different orientation, the image will be rotated by 90 degrees in memory before printing. The machine must have enough working memory to do this. The amount of memory required for a certain paper size depends on the image resolution and the number of bits per pixel.
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Printing
5.3 Adv anc ed Copier T echnology > Digital Proc es se s
CTM > Digital Processes > Printing
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The Latent Image
The diagram show s the typical optical components of a laser printer
5.3 Adv anc ed Copier T echnology > Digital Proc es se s
CTM > Digital Processes > Printing CBT reference > Copier > Digital copier > Laser Exposure The Latent Image Exposure of the photoconductor to the laser beam creates the latent image. A rotating mirror moves the laser beam across the photoconductor to make the main scan while photoconductor rotation controls the sub-scan. The diagram shows the typical optical components of a laser printer. A: Laser Diode Unit B: F theta Lenses C: BTL (Barrel Toroidal Lens) D: Drum Mirror E: Laser Synchronization Detector Board-2 F: Laser Synchronization Detector Board-1 G: Polygon Mirror Motor H: Cylindrical Lens I: OPC Drum J: Toner Shield Glass
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5.4 Process control
Basic concepts OPC digital systems
5.4 Adv anc ed Copier T echnology > Proc es s Control
Study the CTM > Process Control and make sure that you understand: Basic concepts OPC analog systems OPC digital systems OPC analog systems is not explained in this module, but is necessary as basic knowledge to understand process control.
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Basic Concepts
In this section we will take an overall look at process control. Machine conditions that process control compensates for: Dirty optics Exposure lamp deterioration Dirty charge corona wire/grid Change of drum sensitivity Deterioration of developer
5.4 Adv anc ed Copier T echnology > Proc es s Control
Process control is a system that automatically changes machine processes to compensate for changes in the environment or the machine condition. The objective of process control is to stabilize the quality of image output. The practical result is a decrease in the frequency of service calls, thus increasing customer satisfaction and decreasing service cost. To maintain good copy quality, a lot of machines do process control data initial setting just after the main switch is turned on.
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Latent Image & Image Density Control
5.4 Adv anc ed Copier T echnology > Proc es s Control
CTM > Process Control > Basic concepts This illustration represents a copier model that uses two process control methods. One compensates for variation in the drum potential (latent image control) and the other controls the toner concentration and toner supply amount (image density control). All process control components affect one or the other (or both) of these methods.
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Latent Image Control
VO
Drum potential j ust after chargi ng the drum. potential j ust after exposi ng the patter n (V D pattern) potential j ust after exposi ng the patter n (V L pattern)
VD (Dark Potential ) Drum black VL (Li ght Potential ) Drum w hite VR (Residual Voltage )
Drum potential j ust after the exposure of the erase lamp.
5.4 Adv anc ed Copier T echnology > Proc es s Control
CTM > Process Control > Basic concepts The figure in the slide shows the changes of the drum potential during the copy process. The following list explains the meaning of some of the terms and abbreviations used when describing process control. VO (Original Potential) The drum potential after the drum is charged. VD (Dark Potential) The drum potential in black image areas after exposure. Standard VD is the potential measured after exposing a black pattern. VL (Light Potential) The drum potential in white image areas after exposure. Standard VL is the potential measured after exposing a white pattern. VR (Residual Voltage) The drum potential after the drum has been exposed by the erase lamp. Potential Sensor A sensor used to measure the strength of the charge on the OPC drum surface (drum potential). VL Pattern A standard white pattern used for reference. On some machines the VL pattern is actually a light gray tone rather than pure white. VD Pattern A standard black pattern used for reference. ID Sensor A photosensor that measures the image density (reflectivity) of the drum and of a test pattern (ID sensor pattern). The output of this sensor is used to control toner supply. ID Sensor Pattern A standard pattern that is exposed and developed for sensing by the ID sensor.
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5.4 Adv anc ed Copier T echnology > Proc es s Control
VSG The ID sensor output when checking the erased drum surface. VSP The ID sensor output when checking the ID sensor pattern image. VLAMP Exposure lamp voltage. VB or VBB Development bias. TD Sensor Toner density sensor--it measures the concentration of toner in the developer. VREF A targeted control reference for the TD sensor. When VTD becomes too low, toner is added to the developer to bring VTD back to the VREF value. VTD, VT, or VOUT The output voltage of the TD sensor. V Sensor A reflective photosensor similar to the ID sensor that is used to indirectly measure the drum potential. It was used prior to the development of the potential sensor system and will be found in earlier models using process control. VG or VGRID Charge corona grid potential. VH (Halftone Potential) A standard halftone drum potential. This value is used for laser power adjustment in the process control system of some digital products.
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Image Density Control
Toner density sens or (TD sensor) Image density sens or (I D sensor)
ID Sensor
TD Sensor
5.4 Adv anc ed Copier T echnology > Proc es s Control
CTM > Process Control > Basic concepts Data from the TD sensor is used to keep the toner concentration in the developer at a constant level. However, the image on the OPC drum varies due to the variation of toner chargeability (influenced by the environment) even if the toner concentration is constant. By the ID sensor compensation, toner concentration is changed to keep the image density on the OPC drum constant. The following items are controlled to maintain a constant copy image density: Toner supply clutch on time Toner supply level data (VREF) of the TD sensor NOTE: Some machines do not have a TD sensor and use only an ID sensor for image density control.
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OPC digital systems
5.4 Adv anc ed Copier T echnology > Proc es s Control
CTM > Process Control > OPC Digital Systems This training module will mainly focus on digital copiers, but all detail about OPC's for analog systems is explained in the CTM. CTM > Process Control > OPC Analog Systems
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Overview
The drum potential will gradually change because of the following factors: Dirty optics or exposure glass Dirty charge corona casing and grid plate Changes in drum sensitivity
5.4 Adv anc ed Copier T echnology > Proc es s Control
CTM > Process Control > OPC Digital Systems In this OPC digital systems chapter we explain process control based on the model A229 (Aficio650 or SP5). For detail about the different process control descriptions you have to refer to the machines Service Manual and Product trainings.
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Process Control Data Initial Setting
The following is done during process control initial setting: 1. Potential Sensor Calibration (Latent Image Control) 2. Vsg Adjustment (Image Density Control) 3. Vg (Grid Voltage) Adjustment (Latent Image Control) 4. LD Power Adjustment (Latent Image Control) 5. Vref Update (Image Density Control)
Process Con trol Laten t Image Co ntrol Im age Dens ity Con trol
Potential Sensor Calibration
VG Adju stment (VD Co rrection)
LD Power Adj. (VH Correctio n)
Vsg Adju stme nt (ID Sens . Cal.)
Vref Update
5.4 Adv anc ed Copier T echnology > Proc es s Control
CTM > Process Control > OPC Digital Systems To maintain good copy quality, the machine does Process Control Initial Setting just after the main switch has been turned on. NOTE: In most cases it is done if the fusing temperature is less than 100 °C and auto process control is enabled on the machine. Next slides will describe these steps in more detail. Processes 1, 3, and 4 in the above list compensate for changes in drum potential. Processes 2 and 5 are for toner density control.
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Drum Potential Sensor Calibration
(Latent I mage Control)
RA101 -200/-700 RA102
To correct for environmental conditions
5.4 Adv anc ed Copier T echnology > Proc es s Control
CTM > Process Control > OPC Digital Systems The drum potential sensor detects the electric potential of the drum surface. Since the output of the sensor is affected by environmental conditions, such as temperature and humidity, the sensor needs recalibration at times. This is done during process control initial setting. The development power pack has two relay contacts. Usually RA102 grounds the drum. However, to calibrate the sensor, RA102 and RA101 switch over and apply the power pack output voltage to the drum shaft. The machine automatically calibrates the drum potential sensor by measuring the output of the sensor when 200V and 700V are applied to the drum. From these two readings, the machine can determine the actual drum potential from the potential sensor output that is measured during operation. During calibration, if the rate of change in drum potential sensor response to applied voltage is out of the target range, a SC (Service Call) is logged and auto process control turns off. The VG and LD power adjustments are skipped; VG is set to a value stored in a SP (Service Program) mode, and LD power is also set to a value stored in a SP mode. Exercise: Check with help of the Service Manual the following problem Drum Potential Sensor Error See the result in the manual and compare with the result underneath Definition D ¾ The SC history is updated. The machine can be operated as usual. ¾ The SC will not be displayed. All that happens is that the SC history is updated.
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Vsg Adjustment
(Image Density Control )
Y During the process control initial setting or by SP, the ID sensor output is calibrated by changing the LED light intensity
5.4 Adv anc ed Copier T echnology > Proc es s Control
CTM > Process Control > OPC Digital Systems Vsg adjustment calibrates the ID sensor output for a bare drum to a standard value. It does this by changing the intensity of the light shining on the drum from the sensor. This is done automatically during process control initial setting, and it can also be done manually with an SP mode selection. If the ID sensor output cannot be adjusted to within the standard, a SC is logged and toner density control is done using the TD sensor only. Later in this module we will explain more detail about the ID sensor when Image Density control is explained.
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New Drum
Drum Potential -900V VD
Gradations
-300V
VH
VR Light Original Density Dark
5.4 Adv anc ed Copier T echnology > Proc es s Control
The relationship between the drum potential and the original density is illustrated in the characteristic. In this example the drum potential of a new drum is 600 Volts. This means that with this drum potential we have the maximum density from white to solid black.
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Vg Adjustment (VD Correction)
(Latent I mage Control)
The Potential on unexposed areas of the drum (VD) gradually changes during drum life
Charge/Grid P.P
VG
SBICU
VD Must be constant (Target= -900V + 10V)
5.4 Adv anc ed Copier T echnology > Proc es s Control
CTM > Process Control > OPC Digital Systems The potential on unexposed areas of the drum (VD) gradually changes during drum life. To keep VD constant, the grid voltage (VG) is adjusted during process control initial setting. The SBICU checks VD using the drum potential sensor. If it is not within the target range (-900V + 10V), the SBICU adjusts VG (Grid Voltage) through the Charge/Grid power pack to get the correct target voltage. For details of how the machine determines an abnormal sensor detection see the service manual of the copier.
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Older Drum
Drum Potential -900V VD' VD
VH' -300V VH New drum After many copies VR' VR Dark
Light
Original Density
5.4 Adv anc ed Copier T echnology > Proc es s Control
The relationship between the drum potential and the original density is illustrated in the characteristic. To get consistent copy quality throughout the drum's life, this relationship must be maintained. Since this relationship changes due to various factors to the one represented by the red dotted line, compensation is required. Factors causing these changes occur in the optics and charge sections and in drum sensitivity. The residual voltage (VR) cannot be compensated even if exposure lamp voltage is increased. Therefore, the VR change has to be compensated by other means.
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VG Adjustment
Drum Potential -900V VD' VD VG Adjust
VH' -300V VH VR' VR Light Original Density Dark
5.4 Adv anc ed Copier T echnology > Proc es s Control
The drum potential tends to lower during drum life due to a decrease in the drum's capacity to carry a charge. The main control board measures VD through the drum potential sensor and adjusts it to a target value by adjusting the grid bias voltage (VGRID). This is illustrated with the blue dotted line. Now that VD is back to normal you can see that VH is not correct, so the drum potential range is less than the 600 Volts which we had with a new drum. The next adjustment is to bring VH back.
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LD Power Adjustment (VH Correction)
(Latent I mage Control)
LDDR
SBICU
VH Must be constant (Target= -300V + 20V)
5.4 Adv anc ed Copier T echnology > Proc es s Control
CTM > Process Control > OPC Digital Systems This adjustment uses the drum potential sensor to keep the ID sensor pattern at the same density, so that VREF will be updated correctly (see some slides later). The VH pattern is developed using the current LD power (the density is the same as the ID sensor pattern).
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LD Power Adjustment
Drum Potential -900V VD' VD
LD Adjust -300V VH VR' VR Light Original Density Dark
5.4 Adv anc ed Copier T echnology > Proc es s Control
The drum potential sensor detects the potential on the VH pattern. The LD power is adjusted until VH becomes 300V +20V. This is done only during process control initial setting. For details of how the machine determines an abnormal sensor detection please refer to the Service Manual. Now that the latent image is controlled the next thing which has to be done is the Image Density Control with help of the TD & ID sensors.
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Toner Density Sensor
7
Sensor output [V]
6 5 4 3 2 1
Vref
0
1
2
3
4
5
Toner weight [wt %]
5.4 Adv anc ed Copier T echnology > Proc es s Control
Developer consists of carrier particles (iron) and toner particles (resin and carbon). Inside the development unit, developer passes through a magnetic field created by coils inside the toner density sensor. When the toner concentration changes, the voltage output by the sensor changes accordingly. When new developer with the standard toner concentration is installed, developer initial setting must be performed by using an SP mode.
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Toner Supply Criteria
7
Sensor output [V]
6 5 4 3 2 1
VTD > Vref (Toner WT% is small) Increase toner supply
Vref
VTD < Vref (Toner WT% is large ) Decrease toner supply
0 1 2 3 4 5
Toner weight [wt %]
5.4 Adv anc ed Copier T echnology > Proc es s Control
At every copy cycle, toner density in the developer is detected. The sensor output voltage (VTD) during the detection cycle is compared with the toner supply level voltage (VREF).
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Toner Density Control
T oner Supply Clutch On T ime Calculation
Pixel Count
GAIN
T D Sensor Output (V TD )
VT Reference Voltage (VREF) (New VREF) VT Reference Voltage Update VREF Update ID Sensor Output (V SP /VSG) T D Sensor Initial Setting (VREF)
5.4 Adv anc ed Copier T echnology > Proc es s Control
To stabilize toner concentration, toner supply amount (toner supply clutch on time) is controlled by referring to VREF and VTD. The toner supply amount is calculated at every copy.
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Vref Update
(Image Density Control ) Y To sta bilize the concentration of toner i n the dev elopment unit Vre f is updated using Vsp/Vsg and V TD
T oner Supply Clutch On T ime Calculation Pixel Count GAIN
T D Sensor Output (V TD )
VT Reference REF Voltage (V ) (New VREF) VT Reference Voltage Update V REF Update ID Sensor Output (VSP /VS G) T D Sensor Initial REF Setting (V )
5.4 Adv anc ed Copier T echnology > Proc es s Control
CTM > Process Control > OPC Digital Systems Earlier in this module we already explained that during process control initial setting the ID sensor is calibrated with help of the Vsg adjustment. The image on the OPC drum changes due to variation of toner chargeability (influenced by the environment) even if the toner concentration is constant. The image density sensor (ID sensor) directly checks the image on the OPC drum and shifts VREF data to keep the image on the OPC drum constant. VSG and VSP are checked by the ID sensor. There is no ID sensor pattern in the optics, however, a pattern image is made on the OPC drum by the charge corona unit and the erase lamp. Y VSG is the ID sensor output when checking the erased drum surface. Y VSP is the ID sensor output when checking the ID sensor pattern image. To compensate for any variation in light intensity from the sensor LED, the reflectivity of both the erased drum surface and the pattern on the drum are checked.
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5.5 Standard Components
Y Light Sources Y Sensors and Switches Y Clutches, Motors, And Solenoids Y Consumables
5.5 Adv anc ed Copier T echnology > Standa rd Compon ents
Study the CTM > Standard Components and make sure that you understand: Y Light Sources Y Semiconductor Components Y Sensors and Switches Y Clutches, Motors, And Solenoids Y Other Electrical components Y Consumables
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6. Service
6. Servi ce
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Service Manual
CD ROM Hard Copy
6. Servi ce
What is the best way to use the service manual CD ROM's. How to View Files All the technical documents on this disk are in the portable document format (PDF). To view them you must install either Adobe Acrobat Reader or Adobe Acrobat Exchange on your computer. You will find a version of Acrobat Reader for Windows in the RDR_SRCH directory of this disk. Please install it if you haven't already. There are two ways to quickly find the documents that you want on this disk. You can use the main contents file (CONTENTS.PDF) or use the full-text search function. (You will find more detail about this in the readme file on the CD ROM.) Using the Contents File Just open CONTENTS.PDF (in the "Contents" fol