How it Works
Ricoh
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C7200
User Manual
52 pgs3.36 Mb0
Table of contents
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Ricoh C7210X, C7210SX, C7210S, C7200S, C7200X User Manual

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Operating Instructions
Advanced Settings for Custom Paper Adjustment
For safe and correct use, be sure to read Safety Information before using the machine.

TABLE OF CONTENTS

1. Introduction
Basic Procedure.................................................................................................................................................. 3
Advanced Settings..............................................................................................................................................4
2. Mechanism
Xerographic process - Overview...................................................................................................................... 5
Xerographic Process-Laser Exposure................................................................................................................7
Xerographic Process – Development................................................................................................................8
Xerographic Process – Drum-to-Belt Transfer................................................................................................ 10
Xerographic Process – Belt-to-Paper Transfer............................................................................................... 11
Xerographic Process - Fusing.......................................................................................................................... 16
Paper Delivery..................................................................................................................................................20
3. Details of Advanced Settings
Overview.......................................................................................................................................................... 27
Registration....................................................................................................................................................... 28
Image Quality...................................................................................................................................................29
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Paper Feed/Delivery from Mainframe Trays................................................................................................ 39
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1. Introduction

This chapter provides an overview of the Media Library.

Basic Procedure

This machine is capable of printing on a wide variety of media using the latest technologies in digital printing such as the AC transfer and elastic fusing belt.
Also, the introduction of the Clear/White toner - available in the 5-color model - is capable of adding further value to print products.
In addition to the above new technologies and features, support of various media is also made possible by the Media Library database, which is registered with tested and proved media and programmed with optimized print parameters by media type/weight.
How to use the Media Library:
1. Select a media from the library and associate the media to a tray.
2. Set the media on the associated tray.
3. Specify the media in Job Properties of the color controller.
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1. Introduction

Advanced Settings

As described in the previous slide, printing from the Media Library is possible with a simple procedure, however, precise adjustments (such as the transfer and fusing conditions) may be required depending upon the media attributes, which differ by each and every media.
Such precise adjustments can be made from [Tray Paper Settings] [Advanced Settings].
In this menu, the followings can be adjusted:
• Machine: Image Position
• Machine: Image Quality
• Machine: Paper Feed / Output
To effectively adjust the above, it is important to have a basic understanding of how the printer works.
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2. Mechanism

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This chapter provides explanation on the basic Xerographic process of the engine by referring to the items of the Advanced Settings.

Xerographic process - Overview

1. OPC drum
2. Charger roller
3. Laser unit
4. Development roller
5. Image transfer roller
6. Intermediary transfer belt(ITB)
7. Paper transfer roller(PTR)
8. Fusing unit
The electrophotography process consists of the following steps:
Drum charge Laser exposure Development Transfer Fusing
• Drum charge …… The charge roller [2] gives an equal charge across the surface of the OPC drum [1].
• Laser exposure …… Laser beam [3] creates an electrostatic latent image on the OPC drum [1].
• Development …… The development roller [4] carries toner to the latent image on the OPC drum [1].
• Image transfer
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2. Mechanism
Drum-to-belt transfer …… Toner images created on each OPC drum [1] are transferred sequentially to the ITB [6].
Belt-to-paper transfer …… Toner image on the ITB [6] is transferred onto the paper when the paper passes through the PTR [7].
• Fusing …… The fusing unit [8] applies heat and pressure to fuse the toner image onto the paper.
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Xerographic Process-Laser Exposure

Xerographic Process-Laser Exposure

Laser Unit (Exposure)

The laser unit is equipped with the Vertical Cavity Surface Emitting Laser (VCSEL) technology.
40 laser beams are emitted to produce 2400dpi×4800dpi.
Laser beams are reflected on the polygon mirror and lenses to create a latent image on each of the photoconductive drums by imparting static electricity on the surface of the drum.
1. VCSEL
2. Polygon mirror
3. OPC drum
4. Laser beam
Adjusting the start timing and frequency of this latent image creation process in both main and sub scan directions enables registration, masking and scaling of the image.
Related Advanced Settings
page 28 "Image Position/Magnification"
page 36 "Erase margin: leading/trailing edge"
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[1]
[2]
[3]
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2. Mechanism

Xerographic Process – Development

Development

The development system employs the dual-component*1 development method.
The developer is pre-mixed*2 to prevent image quality degradation caused by deterioration of the developer that occurs over time.
Electrostatic latent image areas of the drum attract negatively charged toner particles from the development roller [4].
To maintain consistent amount of toner attraction from the development roller [4] to the drum [1] and stable image quality(toner density), image quality adjustment process runs automatically when turning on the machine power and at optimum timings.
During the image quality adjustment process, toner patterns in 5 gradients are created on the ITB for each toner color, which are read by the toner mark sensors. Xerographic conditions are adjusted according to the sensor readings, maintaining consistent development (maximum image density).
*1
The developer consists of positively charged carrier (+) and negatively charged toner (-).
*2
The carrier is pre-mixed with the toner in the toner bottle and the mixture is supplied to the
development unit to constantly refresh old developer in the development unit with new developer.
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Related Advanced Settings
page 29 "Maximum Image Density"
Xerographic Process – Development
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(Stations greyed out are inactive.)
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2. Mechanism

Xerographic Process – Drum-to-Belt Transfer

Drum-to-Belt Transfer

To enable printing in all five toner colors as well as printing using only special color, the mechanism to contact/separate the ITB and ITB rollers was modified in the drum-to-belt transfer process for the machine. Among the following four print modes, the correct mode is selected according to the print data sent from the printer controller.
• BW mode: Job contains only black data.
• FC mode: Job contains color data.
• FCS mode: Job contains color and special color data.
• S mode: Job contains only special color data.
1. OPC drum
5. Image transfer roller
6. Intermediary transfer belt(ITB)
By applying a positive (+) bias (transfer current) to the image transfer roller, negatively charged toner (-) on the drum is attracted to the ITB that positions between the roller and the belt. Any remaining toner on the drum is cleaned by the drum cleaning unit.
Related Advanced Settings
page 29 "Image Transfer Current"
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Xerographic Process – Belt-to-Paper Transfer

Xerographic Process – Belt-to-Paper Transfer

Belt-to-Paper Transfer

Applied voltage
The AC transfer technology is used for the belt-to-paper transfer, to support printing on textured media.
Negatively charged toner image (-) on the ITB [6] is transferred to the paper by applying a negative bias (-) to the paper transfer bias roller [7].
Following are the two types of negative bias applied to the paper transfer bias roller:
• DC bias: For all media types
• AC bias: When 1218: [Paper Transfer Output: Textured Paper Mode] is enabled
Bias is adjustable by print mode because the optimum bias level is dependent on the amount of toner transfer.
(Bias is higher for FC than for BW/Special due to the greater amount of transferred toner.)
The illustration below describes how AC transfer transfers toner to textured media.
By nature of AC, in which the current flows in an alternating up-and-down movement, toner particles sync with this movement. Toner transferred to the media is pulled back to the ITB to gain further transferability, enabling toner particles to fall into the indentations on the rough surfaced media.
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2. Mechanism
Textured paper mode
1. ITB
2. Textured paper
3. Toner is partially transferred.
4. Toner transferred to the paper returns to the belt and combines with toner remaining on the belt.
5. Toner is transferred to the indentations on the surface of the paper.
1. AC transfer inactive
2. AC transfer active
Bias correction can be adjusted for each imaging mode, because the optimum bias correction value varies depending on the transferred toner. (More bias correction is required for printing in FC/FCS mode, which consumes more toner than printing in BW/S mode.)
Related Advanced Settings
• DC bias
page 30 "Paper transfer current"
• AC bias
page 30 "Textured paper mode"
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Xerographic Process – Belt-to-Paper Transfer
Leading/Trailing edge correction
To prevent image quality problems caused by the unstable condition of the paper when it enters the nip of the PTR, the belt-to-paper transfer bias is adjusted for the leading/trailing edges.
The following are the three bias correction settings that adjust the bias level and duration.
• Belt-to-paper transfer: Constant voltage
• Belt-to-paper transfer: Leading edge correction
• Belt-to-paper transfer: Trailing edge correction
• Current vs. Voltage
• Bias is applied using 'constant current' for drum-to-belt and belt-to-paper transfer, as this method is resilient to changes in operational environment and thickness of the media.
• On the other hand, 'constant voltage' is used for AC bias and as this method does not require adjustments according to paper width.
Related Advanced Settings
page 30 "Paper transfer current: TE"
Shock-jitter canceller
The shock generated and the change in speed when the leading edge enters and the trailing edge exits the nip between the PTR [9] and ITB bias roller [7] may cause image quality problems where unwanted lines appear perpendicular to the paper feed direction (shock-jitter).
To ease the shock, the PTR unit is equipped with the "shock-jitter canceller" function, in which the PTR [9] moves up when the paper enters the nip and moves down when the paper exits the nip.
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2. Mechanism
Related Advanced Settings
page 31 "Paper transfer gap"

PTR Rotation Speed

The PTR [9] has the function to deliver the paper from the paper transfer timing roller.
Since the paper transport speed is controlled by the PTR, if the PTR rotation speed is slower than the target the image will shrink, if faster the target the image will stretch.
Since the paper is simultaneously gripped by the PTR and the paper transfer timing roller, uneven density and banding problems may occur, if the speed differs between these rollers. PTR rotation speed (and paper transfer timing roller speed) is made adjustable for this reason.
Related Advanced Settings
page 47 "Paper transfer roller feed speed"

Paper Separation

Paper is applied with charge when it passes through the PTR.
To discharge this charge, AC bias is applied to the discharge brush [10].
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