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49

When the handset is raised, the switch is turned off, and the signal of IC300-U24pin becomes low level.
When the handset is settled, the switch is turned on, and the signal of IC300-U24pin becomes high level.

The unit consists of a LCD (Liquid crystal display), KEYs and LEDs (light-emitting diodes). They are controlled by the Gate Array
(IC1) on Operation board and IC300 on Main board. 
The key matrix table is shown below.

1. Key Matrix 

a. Hard Scan

*LED7 should be set to KSL4.  "8 x 5" key matrix is executed by hardware scanning. 

SW940

Signal (IC300-U24pin)

ON HOOK

OPEN

High level

OFF HOOK

CLOSE

Low level

KIN0

KIN1

KIN2

KIN3

KIN4

KIN5

KIN6

KIN7

KSL0 AUTO ANSWER S1

S3

MONITOR

↓

*

#

-

KSL1 FAX

S2

ZOOM

FLASH

←

7

0

START

KSL2 COPY

COLLATE

REDIAL

SET

4

9

6

KSL3

CONTRAST

N in 1

MENU

↑

2

5

STOP

KSL4
(LED7)

SCAN

RESOLUTION LOWER

CALLER ID

→

1

8

3

CN2

CN511

IC300

ASIC

LCD MODULE

CN1

8x5
KEYS
MATRIX
(Hard)

LED

MAIN BOARD

OPERATION BOARD

GATE ARRAY IC

IC1

50

2. LED

• AUTO ANSWER LED ON/OFF port---LED6 (IC1-2pin)
• FAX MODE LED ON/OFF port---XLED8 (IC1-5pin)
• COPY MODE LED ON/OFF port---LED5 (IC1-41pin)
• SCAN MODE LED ON/OFF port---LED2 (IC1-36pin)

The Gate Array (IC1) works only for writing the ASCII code from the data bus (D4~D7). V0 is supplied for the LCD drive. 
R118 and R117 are density control resistors. 
Consequently, in this unit, the timing (positive clock) is generated by the LCD interface circuitry in the gate array (IC1).

51

As for the developing voltage, the DC voltage and AC voltage are overlapped and output from an output terminal.
There is one terminal for transcription output and + and - are switched to be output.

When IC300 turns on the transistor Q506, CHG REM becomes “L”, and Charge BIAS (200

µA) is output from CHG OUTPUT.

GRID BIAS is generated by the current flowing in the GRID circuit via charge wire and GRID.

Charge (CHG)

Grid

Developing DC

Developing AC

Transfer (TRA) -

Transfer (TRA) +

Output Characteristics Constant current

Constant voltage

Constant voltage

Constant voltage

Constant current
(Variable)

Constant voltage

Nominal Output Voltage 4.35KV

475±10V

230V±15V
(50~300V)
PWM20%
300M

Ω/220pF

330V±15Vp-p
34KHz

100M

Ω

(-1.48KV)

785V±100V

Nominal Output Current 200±15

µA

(19.4M

Ω)

200

µA

0.73

µA

-----

-14.8

µA±1µA

(0

µA~25µA)

PWM 35%

1000M

Ω

(0.8

µA)

Load Range

18.1M

Ω~20.6MΩ

-----

100M

Ω~2000MΩ

-----

33.8M

Ω~284MΩ

10M

Ω~1000MΩ

Constant Current
Range

4.1~4.6KV

-----

-----

-----

-0.5KV ~ -4.2KV

-----

52

When CHG REM is “L”, 5.425kHz PWM (Pulse Width Modulation) is input from IC300 to DEV CLK through Q504, developing
voltage corresponding to the DUTY of PWM signal is output from DEV OUTPUT. Also DUTY is adjusted by the utilization of the
developing unit and environmental temperature.

330 Vp-p 34 kHz wave of developing AC voltage is output from DEV OUTPUT. This voltage is overlapped with developing DC
voltage and output as AC voltage that includes the development DC voltage.

When CHG REM is “L” and TRA CLK is “open”, Charge BIAS (200

µA) is output from CHG OUTPUT, and at the same time

Transfer (+) BIAS (785V) is output from TRA OUTPUT. When 5.086kHz PWM (Pulse Width Modulation) signal is input to TRA
CLK through transistor Q501, Transfer (-) CURRENT BIAS corresponding to PWM signal is output from TRA OUTPUT.