Ricoh FT 2012 Service Manual

IMPORTANT SAFETY NOTICES

PREVENTION OF PHYSICAL INJURY

1. Before disassembling or assembling any parts of the copier, make sure that the power cord is unplugged.

2. The wall outlet should be near the copier and easily accessible.

3. If any adjustment or operation check has to be made with exterior covers off or open while the main switch is turned on, keep hands away from electrified or mechanically driven components.

4. The inside and the metal parts of the fusing unit become extremely hot while the copier is operating. Be careful to avoid touching those components with your bare hands.

HEALTH SAFETY CONDITIONS

1. Toner and developer are non-toxic, but if you get either of them in your eyes by accident, it may cause temporary eye discomfort. Try to remove with eye drops or flush with water as first aid. If unsuccessful, get medical attention.

OBSERVANCE OF ELECTRICAL SAFETY STANDARDS

1. The copier must be maintained by a customer service representative who has completed the training course on the model.

SAFETY AND ECOLOGICAL NOTES FOR DISPOSAL

1. Do not incinerate toner cartridges or used toner. Toner dust may ignite suddenly when exposed to open flame.

2. Dispose of imaging units in accordance with local regulations. (These are non-toxic supplies.)

3. Dispose of replaced parts in accordance with local regulations.

SECTION 1

OVERALL

MACHINE INFORMATION

4 July 1996 SPECIFICATIONS

1. SPECIFICATIONS

Configuration: Desk Top Copy Process: Dry electrostatic transfer system Originals: Sheet/Book Original Size: Maximum: A4/8.5" x 14" (A183 copier)

B4/10" x 14" (A184 copier)

Copy Paper Size: Paper tray feed:

A4, 8.5" x 11", 8.5" x 13", 8.5" x 14"

Bypass feed:

Maximum: A4/8.5" x 14" Minimum: A5/5.5" x 8.5"

Copy Paper Weight: Paper tray feed: 64 to 86 g/m

Bypass feed: 60 to 105 g/m

, 17 to 23 lb

, 16 to 27 lb

Overall

Information

Reproduction Ratios (A184 model only):

Enlargement

Full Size 100% 100%

Reduction

Metric Version Inch Version

141% 122%

93% 82% 71%

129%

93% 85% 78%

Zoom (A184 model only): From 70% to 141% in 1% steps Copying Speed: 12 copies/minute (A4/8.5" x 11") Warm-up Time:

Less than 30 seconds (at 23°C) First Copy Time: Less than 9 seconds (A4/8.5" x 11") Copy Number Input: Up/Down key, 1 to 50 Manual Image Density

4 steps; can also be set to 5 steps Selection:

Automatic Reset: 1 minute standard setting; can also be set to

3 minutes or no auto reset Paper Capacity: Paper Tray:

250 sheets (A4/8.5" x 11", 80 g/m 100 sheets (8.5" x 14", 80 g/m

Bypass feed entrance: 1 sheet Toner Replenishment: Bottle exchange (91 g/bottle)

1-1

/20 lb)

SPECIFICATIONS 4 July 1996

Copy Tray Capacity:

A4/8.5" x 11" 20 sheets 50 sheets

8.5" x 14" 10 sheets 50 sheets OHP — 1 sheet

Power Source: 120 V/60 Hz:

More than 10 A (for North America)

220 ~ 240 V/50 Hz:

More than 6 A (for Europe)

220 V/50 Hz:

More than 6 A (for Asia)

220 V/60 Hz:

More than 6 A (for Middle East/Asia)

110 V/60 Hz:

More than 10 A (for Taiwan)

127 V/60 Hz:

More than 10 A (for Middle East)

Power Consumption:

Maximum Copy cycle condition Warm-up condiiton Stand-by condition

Copy tray in the

closed position

Copy tray in the

open position

0.9 kW

0.5 kW

0.6 kW

0.1 kW

Dimensions:

Copier

Width Depth Height

400 mm

(15.8")

550 mm

(21.7")

220 mm

(8.7")

Noise Emissions: Sound pressure level (the measurements are

made according to ISO 7779 at the operator position.)

Less than 55 dB Sound power level (the measurements are made

according to ISO 7779)

Stand-by conditio n Less than 40 dB Copy cycle condition Less than 63 dB

Weight: Less than 18 kg, 39.7 Ib

1-2

4 July 1996 SPECIFICATIONS

MEMO

Overall

Information

1-3

COPY PROCESS AROUND THE DRUM 4 July 1996

2. COPY PROCESS AROUND THE DRUM

A184V501.wmf

1-4

4 July 1996 COPY PROCESS AROUND THE DRUM

1. DRUM CHARGE

In the dark, the charge corona unit gives a uniform negative charge to the organic photoconductive (OPC) drum. The charge remains on the surface of the drum because the OPC drum has a high electrical resistance in the dark.

2. EXPOSURE

An image of the original is reflected to the drum surface via the optics assembly. The charge on the drum surface is dissipated in direct proportion to the intensity of the reflected light, thus producing an electrical latent image on the drum surface.

3. ERASE

The erase lamp illuminates the area of the charged drum surface that will not be used for the copy image. The resistance of the drum in the illuminated areas drops and the charge on those areas dissipates.

4. DEVELOPMENT

Positively charged toner is attached to the negatively charged areas of the drum, thus developing the latent image. (The positive triboelectric charge is caused by friction between the carrier and toner particles.)

Overall

Information

5. IMAGE TRANSFER

Paper is fed to the drum surface at the proper time so as to align the copy paper and the developed image on the drum surface. Then, a strong negative charge is applied to the back side of the copy paper, producing an electrical force which pulls the toner particles from the drum surface to the copy paper. At the same time, the copy paper is electrically attracted to the drum surface.

6. CLEANING

The cleaning blade scrapes the toner off the drum. The collected toner is recycled.

7. QUENCHING

Light from the quenching lamp electrically neutralizes the drum surface.

1-5

MECHANICAL COMPONENT LAYOUT 4 July 1996

3. MECHANICAL COMPONENT LAYOUT

1 1098765432

21 20 16171819 1415

1. 2nd Mirror

2. 1st Mirror

3. Exposure Lamp

A184V500.wmf

13. Relay Rollers

14. Paper Feed Roller

15. Toner Bottle Holder

4. Quenching Lamp

5. Charge Corona Unit

6. 6th Mirror

7. Lens

8. Erase Lamp

9. Development Roller

10. 4th Mirror

11. 5th Mirror

12. By-pass Feed Table

16. Registration Rollers

17. Transfer Corona Unit

18. Drum

19. Cleaning Blade

20. Pressure Roller

21. Hot Roller

22. Exit Rollers

23. Copy Tray

24. 3rd Mirror

1-6

4 July 1996 ELECTRICAL COMPONENT DESCRIPTIONS

4. ELECTRICAL COMPONENT DESCRIPTIONS

Refer to the electrical component layout and the point-to-point diagram on the waterproof paper in the pocket for symbols and index numbers.

Symbol Name Function Index No.

Motors

M3 Scanner Drive Motor Drives the scanners (1st and 2nd). 10

Main Motor Drives all th e m ai n unit components except

for the optics unit and fans.

Exhaust Fan Motor Removes hea t from aro und the fusing unit

and blows the ozo ne built up around the charge corona unit to the ozone filter.

Lens and Mirror M ot or (A184 machines only)

Optics Cooling Fan Motor (220 ~ 240 V machines only)

Moves the lens an d 4t h/ 5t h m irr or pos i tio ns in accordance with the selected magnification.

Prevents build- up of hot air in the opt ics cavity. 18

Overall

Information

Clutches

CL1

CL2

Switches

SW1 Main Switch Supplies powe r to th e copier. 28 SW2 Interlock Switch Cuts all power when the upper unit is opened. 29

Sensors

S5 S6 Exit Sensor Detects misfeeds. 30

Toner Supply Clut ch Transfers main motor drive to the toner bottle

gear.

Paper Feed Clutch Transfers main motor drive to the pa per fe ed

roller.

ADS Sensor Detects the backgr ound density of the

original.

Registration Sensor Detects paper end conditions. Checks if

paper is set on the by- pass feed table.

Lens and Mirror H. P. Sensor (A184 machines only)

Scanner H. P. Sensor Informs the CPU when the 1st scanner is at

Toner Density (TD) Sensor

Informs the CPU when the lens and 4th/5t h mirror assem bl y ar e at th e hom e position (full size position).

the home position. Dete cts the ratio o f t o n er to carrier in the

developer.

Solenoid

SOL 1

Registration Sol en oi d Releases the stopper, synchroniz i ng t he

paper-feed tim ing with the origin al scan.

1-7

ELECTRICAL COMPONENT DESCRIPTIONS 4 July 1996

Symbol Name Function Index No.

Printed Circuit Boards

PCB1 Main Cont ro l Boar d Controls all copier functions . 5 PCB2 Scanner Drive Board Controls the sca nner drive motor. 9

PCB3

PCB4

PCB5

Lamps

L1 L2 Fusing Lamp Provides heat to the hot roller. 22 L3

High Voltage Supply Board - CT/B/G

AC Drive / DC Power Supply Board

Operation Panel Board

Exposure Lamp Applies high intensity light to the original for

Quenching La m p (QL ) Neutralizes any charge remai ning on the

Erase Lamp Dis charges the drum ou ts ide of th e i m age

Provides high vo l tage f or the char ge corona, transfer corona and development bi as .

Drives the exposure lamp, fusing lamp and main motor. Rectifies 30 Vac and 8 Vac input and outputs 5 Vdc an d 24 Vdc .

Informs the CPU of the sel ec te d m odes and displays the si t uation on the panel.

exposure.

drum surface aft er cleaning.

area. (Provides leading/trailing edge and side erases.)

Others

TH1 TH2 Fusing Therm i stor Monitors the fu si ng temperature. 21 TF1

TF2

Total Counter (except for -17 machines)

Optics Thermist or Monitors the tem per at ur e ar ound the

Expos ure Lamp Thermofuse

Fusing Thermof use Provide back-up overheat protect ion i n t he

Transformer Steps down the wall voltage to 30 Vac and 8

Keeps track of the total num ber of copies made.

exposure lamp for overheat protect i on.

Provide back-up overheat protection around the exposure lamp.

fusing unit.

Vac.

1-8

SECTION 2

DETAILED DESCRIPTIONS

4 July 1996 DRUM

1. DRUM

1.1 OPC DRUM CHARACTERISTICS

The OPC (Organic Photoconductor) Drum used in this copier is small in diameter (30 mm), ensuring good paper separation. An OPC drum has the characteristics of:

1. Being able to accept a high negative electrical charge in the dark. (The electrical resistance of a photoconductor is high in the absence of light.)

2. Dissipating the electrical charge when exposed to light. (Exposure to light greatly increases the conductivity of a photoconductor.)

3. Dissipating an amount of charge in direct proportion to the intensity of the light. That is, where stronger light is directed to the photoconductor surface, a smaller voltage remains on the drum.

4. Being less sensitive to changes in temperature (when compared to selenium F type drums).

Detailed

Descriptions

5. During the drums’ life, drum residual voltage gradually increases and the photoconductive surface becomes worn. Therefore, some compensation for these characteristics is required.

2-1

DRUM 4 July 1996

1.2 DRIVE MECHANISM

[B]

[A]

A184D500.wmf

The drum [A] is driven by the main motor [B] through idle gears.

2-2

4 July 1996 CHARGE

2. CHARGE

2.1 OVERVIEW

[A]

Detailed

Descriptions

[D][C]

[B]

A184D501.wmf

A184D502.wmf

This copier uses a single wire scorotron to charge the drum. The corona wire [A] generates a corona of negative ions when the high voltage supply unit applies a negative voltage. The stainless steel grid plate [B] ensures that the drum coating receives a uniform negative charge as it rotates past the corona unit.

The exhaust fan [C] causes a flow of air through the charge corona section. This prevents an uneven build-up of negative ions that can cause uneven image density.

An ozone filter [D], which adsorbs ozone (O

) generated by the charge corona, is located beside the exhaust fan. The ozone filter decreases in efficiency over time as it adsorbs ozone. The ozone filter should be replaced every 30 k copies.

2-3

CHARGE 4 July 1996

2.2 CHARGE CORONA CIRCUIT

24 V

GND

CT Trigger

B PWM

CN123-4

CN123-3

CN123-2

CN123-1

CN1-1

CN1-2

CN1-3

CN1-4

DC/DC

Inverter

DC/DC

Inverter

Zener Diode

High Voltage Supply Board-CT/B/G

Ω

3 M

620 V

Drum

To Drum GND

A184D503.wmf

The main board supplies +24 V to the high voltage supply board at CN123-4 as the power source. After the Start key is pressed, the CPU drops CN123-2 from +24 V to 0 V. This activates the charge corona circuit which applies a high negative voltage of approximately –5 k volts to the charge corona wire. The corona wire then generates a negative corona charge.

The grid plate limits the charge voltage to ensure that the charge does not fluctuate and that an even charge is applied to the entire drum surface. The grid plate is connected to ground through a zener diode in the high voltage supply unit. The grid plate drains any charge in excess of –850 V, which is discharged to the ground through the zener diode.

2-4

4 July 1996 OPTICS

3. OPTICS

3.1 OVERVIEW

[C]

[B]

[J]

[A]

[E]

[H]

[D]

[G]

[I]

A184D504.wmf

During the copy cycle, an image of the original is reflected onto the drum surface through the optics assembly as follows:

Light path: Exposure Lamp [A] → Original → First Mirror [B] → Second Mirror [C]

→

Third Mirror [D] → Lens [E] → Fourth Mirror [F] → Fifth Mirror [G] → Sixth Mirror [H] → Drum [I]

[F]

Detailed

Descriptions

This copier has five (metric version) or four (inch version) standard reproduction ratios (A184 copier only) and a zoom function. The operator can also change the reproduction ratio in one-percent steps from 70% to 141%. One stepper motor is used to change the positions of the lens and 4th/5th mirrors to enlarge/reduce the image across the page. Changes in reproduction ratio down the page are achieved by changing the scanner speed (A184 copier only).

The CPU monitors the temperature around the optics through a thermistor which is located on the scanner frame. When the temperature reaches 35°C, the optics cooling fan [J] (230 V machines only) starts rotating to draw cool air into the optics cavity. The fan operates until the temperature drops below 32°C. (However, 120 V machines are not equipped with a cooling fan.) For all models, the machine will stop if the optics cavity overheats to a certain temperature. (See Troubleshooting for details.) In this case, the Start key turns red.

Additionally, a thermofuse on the 1st scanner provides back-up overheat protection. It opens when the temperature reaches 128°C and cuts ac power to the exposure lamp.

2-5

OPTICS 4 July 1996

3.2 SCANNER DRIVE

[H]

[F]

[D]

[C]

[A]

[E]

[B]

A184D505.wmf

[G]

A stepper motor [A] is used to drive the scanners. The first scanner [B], which consists of the exposure lamp and the first mirror,

is connected to the first scanner belt [C]. The second scanner [D], which consists of the second and third mirrors, is connected to the second scanner belt [E]. Both the scanners move along the guide rail [F].

The pulley [G] drives both the first and second scanner belts. The 2nd scanner moves at half the speed of the first scanner. This maintains the focal distance between the original and the lens during scanning.

The scanner home position is detected by the home position sensor [H]. The scanner return position is determined by counting the scanner motor drive pulses.

2-6

4 July 1996 OPTICS

3.3 LENS AND 4TH/5TH MIRROR DRIVE (A184 copier only)

[B]

[D]

[C]

[A]

[E]

[F]

A184D506.wmf

Drive from the lens & mirror motor [A] is transmitted to the timing belt [B] on which the lens unit [C] is clamped. The lens position is changed to provide the proper optical distance between the lens and the drum surface corresponding to the selected reproduction ratio. The home position of the lens is detected by the home position sensor [D]. The main board keeps track of the lens position based on the number of pulses sent to the lens motor.

Detailed

Descriptions

Drive from the lens & mirror motor is also transmitted to the 4th/5th mirror drive cam [E]. As the lens unit position is changed, the cam rotates to change the 4th/5th mirror [F] position to provide proper the focal distance between the lens and the drum.

2-7

OPTICS 4 July 1996

3.4 AUTOMATIC IMAGE DENSITY SENSOR

[A]

A184D525.wmf

sampled area

A184D529.wmf

The auto ID sensor [A], a photodiode, is mounted on the upper front frame. The sensor cover has a hole in it to allow light to fall directly onto the sensor.

Sampling starts 6 millimeters from the leading edge of the original and continues for 11.5 millimeters from the leading edge of original in full size mode. These lengths "a" and "b" will vary depending on the selected reproduction ratio (A184 copier only). The lengths "a" and "b" for each reproduction ratio are calculated as follows:

The photosensor circuit converts the light intensity to a voltage. The detected voltage is amplified and sent to the main board. If less light is reflected from the original (the image is darker), the sensor outputs a lower voltage. The CPU compares the maximum detected voltage with the standard voltage and compensates the copy image density by changing the development bias voltage.

2-8

4 July 1996 OPTICS

3.5 EXPOSURE LAMP VOLTAGE CONTROL

The main board controls the exposure lamp voltage through the ac drive/dc power supply board.

The exposure lamp voltage is determined by the following factors:

Lamp Voltage =Base Lamp Voltage Setting (SP48)

Image Density Adjustment Factor (SP34)

Manual Image Density Setting Factor (SP35)

Correction Factor (SP62)

Reproduction Ratio Correction Factor

1) Base Lamp Voltage Setting

Detailed

Descriptions

The lamp voltage is determined by the SP48 setting. Base Lamp Voltage = SP48 setting x 0.5 (120 V machines)

SP48 setting x 1.0 (230 V machines)

The default setting is: 137 = 68.5 V (120 V machines)

128 = 128 V (230 V machines)

The current lamp voltage can be viewed with SP 51.

2) Image Density Adjustment Factor (SP34) Depending on the SP34 setting, the development bias and the exposure

lamp data are increased or decreased for both ADS and manual ID modes.

SP34 Setting Setting Dev. Bias Exposure Lamp

0Normal0 0 1 Light –40 V 0 2 Dark +40 V 0 3 Lighter –40 V +3 step s 4 Darker +40 V –3 steps 5 Lightest –40 V +7 steps 6 Darkest +40 V –7 st eps

2-9

OPTICS 4 July 1996

3) Manual Image Density Setting Factor Depending on the manual image density setting on the operation panel, the

exposure lamp voltage is changed as shown in the table below:

Manual ID Level 1 2 ADS (3) 4 5

Base Development Bias Voltage (Volts)

Manual Image Setting Factor (Volts)

–200 –200 (–200) –200

– 6 steps

(SP35)

– 3 steps V

V0: Base lamp voltag e set t ing ( SP48)

V0 + 3 steps V0 + 7 steps

LighterDarker

–240

(SP36)

1 step = 0.5 V (120 V machines) or 1.0 V (230 V machines) The manual setting factor for ID level 1 can be changed using SP35.

SP35 Setting Image Adjustment at ID Level 1

0 –6 steps 1 –8 steps 2 –10 steps

4) VL Correction Factor The light intensity may decrease because of dust accumulated on the optics

parts. Additionally, the drum sensitivity gradually decreases during the drum’s life. This may cause dirty background on copies. To compensate this, V

correction is done. The exposure lamp voltage is increased by +1.0 V (230 V machines), or

+0.5 V (120 V machines) at the set copy count interval. The table below shows the relationship between the SP setting and the interval.

SP62 Setting VL Correction Interval

0 1 step/1500 copies 1 1 step/1000 copies 2 1 step/2000 copies 3 1 step/500 copies 4 1 step/2500 copies 5 1 step/250 copies 6 1 step/3000 copies 7 1 step/4000 copies 8 No Correction

(Default setting: 0)

2-10

4 July 1996 OPTICS

5) Reproduction Ratio Correction Factor The exposure lamp voltage is increased depending on the selected

magnification ratio in order to compensate for the change in concentration of light on the drum.

Magnification Ratio Reproduction Ratio Correction Factor

70% to 72% +4 steps 73% to 78% +2 steps 79% to 119% 0 120% to 129% +4 st eps 130% to 141% +8 st eps

Detailed

Descriptions

2-11

ERASE 4 July 1996

4. ERASE

4.1 OVERVIEW

abcdefg abcdefgh

[A]

A184D507.wmf

A184D508.wmf

The erase lamp [A], which is installed in the upper unit, consists of a single row of LEDs extended across the full width of the drum. The erase lamp has the following functions: leading edge erase, side erase (A184 copier only), and trail edge erase.

2-12

4 July 1996 ERASE

4.2 LEAD EDGE ERASE

The entire line of LEDs turn on when the main motor turns on. They stay on until the erase margin slightly overlaps the lead edge of the original image area on the drum (Lead Edge Erase Margin). This prevents the shadow of the original edge from being developed on the copy. At this point, side erase starts (A184 copier only). The width of the leading erase margin can be adjusted using SP41.

4.3 SIDE ERASE (A184 COPIER ONLY)

Based on the reproduction ratio, the LEDs turn on in blocks (labeled "a" - "h" on the previous page). This reduces toner consumption and drum cleaning load.

The CPU determines which blocks to turn on based on the selected reproduction ratio as follows:

Reproduction Ratio (%) Blocks ON

70 to 72 a - g

73 and 74 a - f

75 to 77 a - e 78 and 79 a - d 80 and 81 a - c

82 to 84 a - b

85 to 141 a

Detailed

Descriptions

4.4 TRAILING EDGE ERASE

This minimizes toner consumption. The entire line of LEDs turns on after the trailing edge of the latent image has

passed 10 mm from the erase lamp. The length of the latent image is determined by the paper length which is checked by the registration sensor. The LEDs stay on to erase the leading edge of the latent image in the next copy cycle. After the final copy, the erase lamps turn off at the same time as the main moto r .

2-13

DEVELOPMENT 4 July 1996

5. DEVELOPMENT

5.1 OVERVIEW

[C]

[D]

[A]

[E]

[B]

A184D509.wmf

When the main motor turns on, the development roller [A] and two agitators [B] and [C] start turning.

There are permanent magnets in the development roller which attract the developer (which is about 50 µm in diameter) to the roller. The turning sleeve of the development roller carries the developer past the doctor blade [D] which trims the developer to the desired thickness.

The development roller sleeve continues to turn, carrying the developer to the drum [E]. When the developer brush contacts the drum surface, the negatively charged areas of the drum surface attract and hold the positively charged toner. In this way, the latent image is developed.

The development roller is given a suitable negative bias for preventing toner from being attracted to the non-image areas on the drum which may have a residual negative charge. The bias also controls image density.

2-14

4 July 1996 DEVELOPMENT

5.2 DRIVE MECHANISM

[B]

[C]

Detailed

Descriptions

[A]

A184D510.wmf

When the main motor [A] turns on, the drive is transmitted to the development roller gear [B] through idle gears. The rotation of the development roller gear is transmitted to the agitator gears [C] through idle gears.

2-15

DEVELOPMENT 4 July 1996

5.3 CROSS-MIXING

[B]

[D]

[C]

[A]

A184D511.wmf

A cross-mixing mechanism is used to keep the toner and developer evenly mixed. It also helps agitate the developer to prevent developer clumps from forming and helps create the triboelectric charge.

Two agitators (helical coils) [A] and [B] are used for the cross-mixing. The 1st agitator [A] moves the developer from left to right. The toner supplied from the cutout in the toner cartridge holder is mixed with the developer by the 1st agitator. The 2nd agitator [B] rotates in the opposite direction and moves the developer back from right to left. In this way, the developer is evenly distributed in the development unit.

The magnets in the development roller [C] attract the developer, and the development roller sleeve rotates to carry the developer to the drum. The doctor blade [D] trims the developer on the development roller to the desired thickness.

2-16

4 July 1996 DEVELOPMENT

5.4 DEVELOPMENT BIAS FOR IMAGE DENSITY CONTROL

The image density is controlled by changing two items: the amount of bias voltage applied to the development roller sleeve, and the amount of voltage applied to the exposure lamp.

Applying a bias voltage to the development sleeve reduces the potential between the development roller and the drum, thereby reducing the amount of toner transferred. As the bias voltage becomes greater, the copy becomes lighter.

The method of control depends on whether the image density is manually selected or auto image density is used.

The development bias voltage applied to the development roller sleeve has the following factors:

Development bias voltage = Base bias voltage factor

(Manual ID level 5: SP 36)

+ Image density adjustment factor (SP34)

+ Drum residual voltage (V

) correction factor

Detailed

Descriptions

The base bias voltage for non-image areas (between copies) is –200 volts. The above correction factors are also applied.

NOTE:

SP34 (Image Density Adjustment) is applied for both ADS and manual ID modes. SP36 is for manual ID level 5 only.

5.4.1 Base Bias Voltage Factor In Manual Image Density Mode

Manual ID Level 1 2 ADS (3) 4 5

Base Bias Voltage (Volts)

Base Exposure Lamp Voltage (Volts)

–200 –200 (–200) –200

– 6 steps

(SP35)

– 6 steps V

V0 + 3 steps V0 + 7 steps

: Depends on the setting of SP48

–240

(SP36)

The base voltage applied at each ID level is shown in the above table. Normally, notch 3 is used for the ADS mode. If SP mode 19 is changed from 0 to 1, ADS mode is disabled and notch 3 is used for the center setting of the manual ID level. The base exposure lamp voltage also varies depending on the manual ID level as shown.

2-17

DEVELOPMENT 4 July 1996

Adjustment factor for manual ID level 5 (SP36)

The base bias voltage at manual ID level 5 can be changed using SP36 as follows:

Image Density SP36 Setting

Normal 0 –40

Lighter 1 –80

Lightest 2 –120

Base Bias Voltage Change for Level 5

(Volts)

(Default setting: 0)

5.4.2 Base Bias Voltage Factor In Automatic Image Density (ADS) Mode

In ADS mode, the base exposure lamp voltage is fixed at V

(this value is

determined by SP48). Image density is controlled by changing only the base bias voltage.

The base bias voltage for ADS mode depends on the background image density of the original which is measured by the ADS sensor. (See page 2-8 for more information about the ADS sensor).

The CPU checks the voltage output from the automatic ID circuit. This circuit has a peak hold function. The peak hold voltage corresponds to the maximum reflectivity of the original. The CPU then determines the proper base bias level with reference to the peak hold voltage.

The table below shows the relationship between the original background density (ADS voltage ratio) and the base bias voltage.

Base Bias Voltage

α =

ADS0

ADS Voltage Ratio [α] (%)

80 to 100 (light) –200 V

75 to 79 –240 V 70 to 74 –280 V 60 to 69 –320 V 29 to 59 –360 V

0 to 28 (dark) –380 V

ADS0

+ (Total VL Correction Steps so far + Reproduction Cor rect ion St eps) x 0.5

: ADS Reference Voltage

ADS Output Voltage

2-18

4 July 1996 DEVELOPMENT

5.4.3 Image Density Adjustment Factor

Using SP 34, the base bias voltage and the exposure lamp data can be increased or decreased for both ADS mode and all manual ID levels as follows:

SP34 Setting Setting Dev. Bias Exposure Lamp

0Normal0 0 1 Light –40 V 0 2Dark+40 V0 3 Lighter –40 V +3 steps 4 Darker +40 V –3 steps 5 Lightest –40 V +7 steps 6 Darkest +40 V –7 steps

(Default setting: 0)

5.4.4 Dru m Residual Voltage (VR) Correction Factor

Detailed

Descriptions

During the drum’s life, drum residual voltage (V

) will gradually increase. To

compensate for this, the bias voltage is increased by –10 V every 5 k copies. The V

correction is done up to 20 k copies. The VR correction will not

change after 20 k copies.

2-19

+ 142 hidden pages