Epson Stylus 800, Stylus 1000 Service Manual 2

Chapter 2

Operating Principles

2.1 Overview................................................................................................................2-1

2.2 Printer Mechanism Operating Principles ...........................................................2-1

2.2.1 General Description ...............................................................................................................2-1

2.2.2 Printing Mechanism ...............................................................................................................2-2

2.2.2.1 Printing Process ........................................................................................................2-3

2.2.2.2 Printing Methods........................................................................................................2-3

2.2.3 Carriage (CR) Mechanism...................................................................................................... 2-4

2.2.4 Paper Feed Mechanism..........................................................................................................2-5

2.2.5 Platen Gap (PG) Adjust Mechanism ..................................................................................... 2-6

2.2.6 CR Lock Mechanism ..............................................................................................................2-6

2.2.7 ASF Mechanism...................................................................................................................... 2-7

2.2.8 Ink System...............................................................................................................................2-9

2.2.8.1 Pump Mechanism.................................................................................................... 2-10

2.2.8.2 Capping Mechanism................................................................................................ 2-12

2.3 Electrical Circuit Operation Principles.............................................................2-13

2.3.1 C202 PSB/PSE board............................................................................................................ 2-13

2.3.2 C202 MAIN Control Board....................................................................................................2-15

2.3.2.1 Printhead Driver Circuit ........................................................................................... 2-16

2.3.2.2 Reset Circuits..........................................................................................................2-18

2.3.2.3 Motor Driver Circuits................................................................................................ 2-19

2.3.2.4 Sensor Circuits........................................................................................................2-20

2.4 Ink System Management....................................................................................2-21

2.4.1 Ink System Operations.........................................................................................................2-21

2.4.2 Timers and Counters............................................................................................................2-22

2.4.3 Ink System Sequence...........................................................................................................2-23

Operating Principles

2.1 Overview

This chapter provides information on the printer mechanism, electrical circuit, and ink system. The operating principles for each mechanism in the printer mechanism is described individually. The description for the electrical circuit is divided into 2 parts; C202 PSB/PSE board and C202 MAIN board.

2.2 Printer Mechanism Operating Principles

2.2.1 General Description

This printer is m ainly composed of the printing m echanism , paper feed m echanism , car riage m echanism , pump mechanism, and ASF mechanism. There are 3 motors, carriage motor (CR motor), paper feed motor, (PF motor) and pump motor. Table 2-1 shows each motor and corresponding units and assem blies driven.

Table 2-1. Motor and Unit/Assembly Driven

Motor Unit/Assembly driven

PF motor PF roller assembly, CR lock lever CR motor CR unit, Capping unit Pump motor Pump unit, Capping unit, Wiper, ASF unit

When the PF Motor rotates clockwise, the torque is us ed to drive PF Roller assembly and release CR Lock Lever, while the torque is used to set the CR Lock Lever when the PF Motor rotates counterclockwise. The CR motor transmit the torque via Timing Belt to shift the CR unit in the both right and lef t direc tions in parallel with the Platen. The torque from the Pump Motor, switched by the disengage mechanism, is transmitted to the ASF and the Pump m otor. The figure below shows the structure bloc k of the printer mechanism .

CR Motor

Pump Motor

PF Motor

Carriage Mechanism

Slider Mechanism

Disengage Mechanism

Figure 2-1. Printer Mechanism Block Diagram

Print Mechanism

Black

Pump Mechanism

ASF Mechanism

Paper Feed Mechanism

CR Lock Mechanism

Color

Rev. A

2-1

EPSON Stylus

&2/25

800

2.2.2 Printing Mechanism

The printing method used for this printer is O n-demand ink jet s ystem, same as for other EPSON ink jet printers. This printer, however, uses newly designed MACH Head, which ensures a high level of printing quality at a higher speed. This printer is equipped with separate printheads of the same type; one for black and one for each of the three colors (magenta, cyan, and yellow). Quick penetration, the type of black and color ink, is also im proved for this pr inter, which enables the users to have the printing im age in the high quality on the normal paper.

 Printhead

The black and color printheads for this printer use the newly designed MACH Head (E-CHIPS Head). The structure of the printhead is the same as for previous CHIPS Head except for the nozzle configuration. The Black Head for this printer has 128 nozzles (32 nozzles for each of 4 rows ) which is as twice as many as previous EPSON ink jet printers , and the Color Head has 192 nozzles (32 nozzles for each of 6 rows) which is 3 times as many as previous EPSON ink jet printer s. Theref ore printing quality as well as the speed for this printer is higher than ever. The nozzle structure for this printhead is shown in the figure below.

Printhead Driver Board

Ink Cartridge Sensor Lever

Cartridge Needle

(Ink Cartridge)

PZT

Cavity

Nozzle Plate

Filter

Ink Tube

Figure 2-2. Printhead Structure

PZT

PZT is an abbreviation of the Piezo Electric Element. Print signal from C202 MAIN board is sent through the driver board on the Printhead unit and to the PZT. Then, the PZT pushes the top cavity which has ink stored, and makes the ink discharge from each nozzle located on the nozzle plate.

Cavity Set

Ink which is absorbed from ink cartridge goes through the filter and will be stored temporarily in this tank, which is called “cavity” unit driven by PZT.

Nozzle Plate

The board with nozzle holes on the Printhead surface is called Nozzle Plate.

Filter

When the ink cartridge is installed, if any dirt or dust around the cartridge needles are absorbed into the head inside, there is a great possibility of causing nozzle clog and disturbance of ink flow and finally causing alignment failure and dot-missing. In order to prevent this, filter is set at cartridge needle below and ink is once filtered here.

Rev. A

Operating Principles

2.2.2.1 Printing Process

Steps bellow describes how the on-demand ink jet system ejects the ink from each nozzle in the printhead.

Step 1>Normal state

When the print signal is not output, PZT also dose not move in the waiting state (normal state).

Step 2>Ejecting state

When the print signal is output from the C202 MAIN board, Nozzle selector IC mounted on the head driver board latches the data once by 1-byte unit. Appropriate PZT latched by nozzle selector is pushed in to the cavity by applying common voltage from the C202 MAIN board. By this operation, ink that is stored in the cavity pops out from nozzles.

Nozzle

Normal State

Piezo

Cavity

Ejected ink

Ejecting State

Figure 2-3. Print Process

During the ink charging or cleaning operation, the ink left in the cavity is vacuumed out by the Pump mechanism via Capping unit, then is ejected to the waste ink tank . The cavity is refilled with ink from the Ink Cartridge during the printing or other operations. The viscosity of the ink tends to change according to the temperatures around the heads, and the change in vis cosity results in the low printing quality. This is, however, avoided by attaching the thermistor directly to the driver circuit board. It is used to determ ine the proper drive pulse automatically according to the detected temperature.

2.2.2.2 Printing Methods

This printer has 3 kinds of diff erent dot to com pos e the print im age; Norm al dot, Double f iring Norm al dot, and Micro dot. Each dot is selected to control printing depending on the conditions s uch as the paper type and the print resolution set through the printer driver.



Normal dot / Double Firing Normal dot printing mode

Normal dot/Double firing Normal dot printing modes are available for the both black and color printings. Normal dot printing mode is designed to form single dot with 2 head drive pulses. With this mode, the dot diameter is expanded to solve the white banding problem which occurs during solid printing at 360 dpi. This printer is, however, designed to use less ink than other printers do to perform printing at 1440 dpi, the maximum solution on the horizontal line. Therefore the Double firing Normal dot and Normal dot used for this printer is considered equivalent to the Normal dot mode and Micro dot mode used for previous ink jet printers respectively. Double firing Normal dot mode is normally selected for printing at 360 dpi, and the Normal dot mode is used for printing in 720 X 360 dpi or 720 dpi X 720 dpi, depending on the paper type.



EPSON Micro dot printing

Both black and color printings can be performed in the Micro dot printing mode. In the Normal dot printing, one dot is formed with 2 pulses. On the other hand, EPSON micro dot printing mode forms one dot with single pulse using less ink. As mentioned above, the Micro dot printing for this printer is controlled to use less ink to create images at 1440 dpi, the maximum solution on the horizontal line. This mode is used for printing at 720 dpi or 1440 dpi by controlling the firing duty of the ink.



Micro Weave Printing

This function is developed to enhance quality in graphic image by eliminating white banding which occurs on each line. This printer is equipped with a new micro weave printing mode and is controlled to form a horizontal line using 2 different types of nozzle. With this mode, the printer can prevents color inks from mixing with each other before drying and can provide clearer colors in the output. The Micro Weave printing can be selected through the printer driver.

Rev. A

EPSON Stylus

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800

2.2.3 Carriage (CR) Mechanism

The CR mechanism is composed of the CR motor, Timing Belt, CR Guide Shaft, Top Frame, and Home Position (HP) sensor. The torque from the CR motor is transmitted to the CR unit via the Timing Belt to move the CR unit along the CR Guide Shaft both right and left, depending on the direction in which the CR motor rotates. W hen the CR unit returns to the HP position, it is detected by the HP sensor mounted on the right end of the Top Frame, and the information is fed back to the IC2 gate array (E05B33CB). Figure 2-4 illustrates the CR mechanism conception. The CR motor, which drives the CR mechanism, is a 4-phases/200-pole/HB type stepping motor and is

CR Motor

HP Sensor

CR Unit

CR Motor Pinion Gear

Sub Pulley

Timing Belt

CR Guide Shaft

Figure 2-4. Carriage Mechanism

controlled by the constant current bipolar control system. The current control signal for eac h phase and phase control signal output from the IC2 gate array E05B33CB are converted into the CR m otor control signal by the IC13 bipolar driver UDN2917EB to control the CR motor. Refer to Table 2-2 and Table 2-3 which show the CR specification and the drive frequency.

Table 2-2. CR Motor Specification

Item Description

Motor type 4-phases / 200-pole / HB type stepping motor Drive voltage Coil resistance Inductance

42 VDC ± 5%

7.8 Ω ± 10% (at 25° C per 1 phase)

14 mH ± 20% (1 KHz, 1 Vrms) Drive frequency 240 ~ 4080 Hz Excitation mode Bipolar drive Minimum step 1/120 inch / pulse (2-2 phase drive), 1/240 inch / pulse (1-2 phase

drive)

1-480 inch / pulse (W1-2 phase drive)

Table 2-3. CR Motor Drive Terms

Mode CR speed

(CPS)

Drive

frequency

Drive system and acceleration/deceleration

step

Acceleration/ De celeration

(Hz) A*2:1, D*3:2 A:2, D:2 Constant pulse*

Fast skip 340 4080 64 (W1-2) 164 (2-2) (2-2) 180 DRAFT 266.7 3200 88 (W1-2) 86 (2-2) (2-2) 108 LQ 200 2400 432 (W1-2) TEXT LQ 200 2400 240 (W1-2) SLQ 100 1200 432 (W1-2) Capping 90 1080 64 (W1-2) wiping 2 80 960 64 (W1-2) Wiping 40 480 16 (W1-2) Capping

20 240 8 (W1-2)

      

(W1-2) 108 (W1-2) 60 (W1-2) 108 (W1-2) 16 (W1-2) 16 (W1-2) 4

(W1-2) 2 (open) Constant

20 240



(W1-2)



value

Note) *1: Step : reduced to 2-2 phase

*2: Acceleration *3: Deceleration

Rev. A

Operating Principles

2.2.4 Paper Feed Mechanism

This printer is equipped with the PF motor which is used to feed paper only to improve f eeding s peed. The drive from the Pump motor is used to load paper at the ASF and the drive from the PF roller is independently used to feed paper only. The paper f eed mec hanism is classif ied to 2 parts; the paper f eed part having the PF roller for the main assembly, and the paper eject part having the Paper eject roller for the main assembly. The PF roller is coated with the powdery material, which is used to improve the paper feed accuracy. The PF motor located at the rear left part of the printer mechanism tr ansmits the torque via the Combination gear (14, 31.5) and Gear (70) to the PF roller assembly to feed paper loaded. The torque is then transm itted from the Gear (17) on the Paper feed roller assem bly to the Paper eject roller via the Gear (19) to eject paper. The torque is transmitted in the following order:

Paper feed part



1) PF motor pinion gear → 2) Combination gear 14, 31.5 → 3) Gear 70 → 4) PF roller assembly

Paper Eject part



1) PF motor pinion gear → 2) Combination gear 14, 31.5 → 3) Gear 70 → 4) Gear 17 (PF roller assembly) → 5) Gear 19 (Front paper guide assembly ) → 6) Paper eject roller assembly (Front paper eject assembly)

Gear 70

PF Motor Pinion Gear

PF Motor

Combination Gears 14, 31.5

Gear 19

Gear 17

Paper Eject Roller

PF Roller Assembly

Paper Guide Assembly (Front)

HP Sensor

Timing Belt

CR Motor

CR Unit

Figure 2-5. Paper Feed Mechanism

This printer uses a 4-phases/96-pole/HB type pulse motor which is controlled by the bipolar constant voltage system for the PF motor. The current control signal for each phase and phase control signal output from the IC2 gate array E05B33CB are converted into the PF motor control signal by the IC16 bipolar driver UDN2917EB to control the PF motor. Since the power switch of this printer is wired to the secondary circuitry, the voltage remains the constant level until the loaded paper is ejected after the printer power is turned off. Table 2-4 and Table 2-5 show the PF motor specification and PF motor drive frequency, respectively.

Table 2-4. PF Motor Specification

Item Description

Motor type 4-phases / 96-pole / HB type pulse motor Drive voltage Coil resistance Inductance

42 VDC ± 5% (The voltage applied to the driver)

7.8 Ω ± 10% (at 25° C per 1 phase)

14 mH ± 20% (1 KHz, 1 Vrms) Drive frequency 400 ~ 4320 Hz Excitation mode Bipolar drive Minimum step 1/120 inch / pulse (2-2 phase drive)

Table 2-5. PF Motor Drive Terms

Mode

Feeding

speed-

Drive

Frequency

Pulse

interval-

Acceleration step

for each phase

Deceleration step

for each phase

(inch/s) (Hz) (us) W1-2 2-2 1-2 W1-2 2-2 1-2

Normal feed 5 3600 278 Fast feed 6 4320 231 Slow feed 2.5 1800 556 At loading 3 22160 463

Micro adjust 1 1.25 900 1111 2 Micro adjust 2 0.55 400 2500

   



50 60 20 30

   



50 60 20 30

   



Note) Drive frequency and pulse interval are reduced to 2-2 phase.

Rev. A

EPSON Stylus

&2/25

800

2.2.5 Platen Gap (PG) Adjust Mechanism

The PG adjust mec hanism, located at the lef t of the printer m echanism , consists of the PG lever, PF sub lever, right/left parallelism adjust bushings, and CR guide shaft. PG adjust mechanism is equipped to keep the proper platen gap according to the paper thickness to prevent ink from having friction. The PG lever joins to the CR guide shaft which has an eccentr icity via PG sub lever, and switching the lever from “0” to “+” rotates the CR shaft and the platen gap changes from narrow to wide. Figure 2-6 show the PG adjus t mechanism .

PG Lever Position +

PG Lever Position 0

PG Lever

PG Sub Lever

CR Guide Shaft

Figure 2-6. PG Adjust Mechanism

2.2.6 CR Lock Mechanism

The CR lock lever, locate at the right side of the printer mechanis m, is composed of the PF motor, PF roller assembly, Stopper lever (CR lock lever) and so on. When there is no paper loaded and no data stored, CR lock m echanism fixes the CR unit to the c apping position. This operation is accom plished by rotating the PF motor clock wise with the specified steps to set the stopper lever at the r ight end of the PF roller to the left of the CR unit. The stopper lever is then r elease fr om the set position when the PF m otor rotates counterclockwise with the specified steps. The drive from the PF motor is transmitted in the following order;

1) PF motor pinion gear 2) Combination gear 14, 31.5 3) Gear 70

4) PF roller assembly 5) Stopper lever

The figure below shows the CR lock mechanism.

PF Motor Pinion Gear

PF Motor

Combination Gears 14, 31.5

PF Roller Assembly

Timing Belt

HP Sensor

CR Motor

Gear 70

Gear 19

Gear 17

Paper Eject Roller

Paper Guide

(Front)

Compression Spring

5.85

Stopper Lever

Figure 2-7. CR Lock Mechanism

Rev. A

Operating Principles

2.2.7 ASF Mechanism

ASF mechanism, which consists of the Pum p motor, slider mechanism , disengage mechanism , and ASF unit, loads paper into the paper feed mechanism. When the CR unit returns to the home position, it pushes the slider in the slider m echanism to the right and the Gear (16) in the slider m echanism then comes to engage with the Change cam in the dis engage mechanism. W ith this m otion, the Pump m otor rotates with the specified steps in the counter c lock wise, which switches the Change c am to the ASF unit side, then the torque from the Pum p motor is transmitted to the ASF unit. The pr ocess in which the drive from the pump unit is switched to the ASF unit side is described below. Figure 2-8 illustrates the process for the switching operation.

Disengage mechanism switch process



1) CR shifts to the home position.

2) Slider shifts to the right end. (Slider mechanism)

3) The Gear (16) is engaged to the Change cam in the disengage mechanism. (Slider mechanism)

4) The Change Cam is switched to the ASF side. (Disengage mechanism)

5) The Combination Gear (14.4, 21.6) shifts to the left.

The figure below shows movement of above mentioned process 3) to 5).

Combination Gear 12, 20.8

Combination Gears 12, 26

Pump Motor Pinion Gear

Pump Motor

Gear 11.5

Gear 27.2

Gear 16.8

Combination Gears

14.4, 21.6

Cam

Gear 16 (Slider Mechanism)

Combination Gears 12, 15

Slider Shaft

Figure 2-8. ASF Mechanism

Transmission process of the Pump motor’s torque



1) Pump motor pinion gear2) Combination gear 12, 26 3) Combination gear 14.4, 21.6

4) Gear 16.8 5) Combination gear 12, 20.8 6) Gear 27.2 (ASF unit)

7) LD roller shaft (ASF unit)

Note) This order has no relevance to the order in the figure above.

The ASF home position is sensed by the detection wheel attached to the right end of the LD roller shaft and ASF HP sensor, and the detected condition is fed back to the IC2 E05B33CB. The ASF motor is controlled based on the home position which is detected by the ASF HP sensor. A 4-phase/48 -pole PM type pulse motor is used for the pump motor which is controlled by the constant current bipolar drive. T he current control signal for each phase and phase control signal output from the IC2 gate array E05B33CB are converted into the pump motor control s ignal by the IC6 bipolar driver UDN2917EB to control the PF motor. Table 2-6 and Table 2-7 show the pump motor specification and pump motor drive frequency, respectively.

Table 2-6. Pump Motor Specification

Item Description

Motor type 4-phases / 48-pole / PM type pulse motor

Drive voltage

Coil resistance

42 VDC ± 5% (The voltage applied to the driver)

9.3 Ω ± 10% (at 25° C per 1 phase)

Drive frequency 272 ~ 654 Hz

Excitation mode Bipolar drive

Minimum step 1/218 inch / pulse (2-2 phase drive)

Rev. A

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