Infinity EX Printhead Lift.pdf - 第6页

INFINITY EX PRINTHEA D LIFT MODU LE ELECTRICA L DETAIL 8.6 Technical Reference Manu al Chapter Issu e 2 Jan 04 Head Pr op Stowed Senso r The head prop stowed sensor switch is f itted to prev ent inadv ertant lo wering of…

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PRINTHEAD LIFT MODULE

ELECTRICAL DETAIL

Chapter Issue 2 Jan 04 Technical Reference Manual 8.5

Head Down

Overtravel Switch

If the head is lowered and the printhead down reed switch is not seen by the

controller, the actuator continues to drive the head down. This action could

result in some machine damage as the actuator plunger would continue to drive

up into the head lift bar. To prevent this the motor output is switched off by the

head down over travel switch. This switch is wired in series with the supply to

the two handed control relay and when activated immediately cuts power to the

motor.

The head down over travel switch also prevents the head lift motor from driving

down should the head become jammed whilst moving.

Figure 8-3 Head Down Overtravel Switch

Printhead Up

Reed Switch

Printhead Down

Reed Switch

Head Lift Bar

Part View on Printhead Actuator

(Viewed from rear of machine)

View on Switch and Clevis

(Plan View)

Clamp

Clevis

Switch

Tab

INFINITY

PRINTHEAD LIFT MODULE

ELECTRICAL DETAIL

8.6 Technical Reference Manual Chapter Issue 2 Jan 04

Head Prop Stowed

Sensor

The head prop stowed sensor switch is fitted to prevent inadvertant lowering of

the printhead whilst the head prop is fitted.

If an attempt to lower the printhead is made without the head prop fitted in the

stowage position, the jog buttons are disabled and the warning window ‘Haz-

ardous Operation - The head is about to be lowered. Remove the head prop

and confirm that everyone is standing clear’ remains displayed.

The sensor is of the solid state micro switch type. An internal magnetic source

is moved by an external push button, the resultant magnetic flux is detected and

the output is switched by anopen collector transistor. The switch does not have

the inherent problems of a conventional metal contact arrangement.

Figure 8-4 Head Prop Stowage

Head Prop stowed inside printhead cover

Viewed on Front of Machine

Head Prop

Head Prop Stowed Sensor

RH Support Block

INFINITY

PRINTHEAD LIFT MODULE

ELECTRICAL DETAIL

Chapter Issue 2 Jan 04 Technical Reference Manual 8.7

Head Lift Circuit

Operation

The head lift power driver card provides motor drive to the head lift actuator

enabling the head to be driven up or down.

Two 16A relays on the card switch the motor drive voltage to enable the actuator

to drive the head in both directions. The DIR signal from MultiMove Source 6

(PL20) controls the change-over of the relay contacts by switching the relays on

or off.

When ENABLE from MultiMove Source 7 (PL20) is high, the Darlington pair

output driver device Q3 switches on making motor drive voltage available to the

head lift actuator.

Figure 8-5 Simplified Headlift Actuator Circuit

Error Conditions

Thermal Overload Q3 is thermally linked to RT1 a thermal over temperature trip device, should the

motor current cause a temperature rise to an unacceptable level, RT1 triggers

the gate of the thyristor Q4. This action turns Q3 off.

Current Overload Q1 and associated sense resistors R5, R6, R7, R8 and R10 sense the current

through Q3 and hence the motor. If a condition exists where the acceptable

current level is exceeded, Q1 switches on bringing Q4 on as described for the

thermal overload error condition.

ERROR indication ERROR indication is provided by the circuit associated with Q2 and D4 the red

led. Error indication is an input to the MultiMove backplane (IN8) at SK13A.

Circuit Protection The circuit is protected from the back e.m.f’s of the motor and the relays by D6

and D7 respectively (not shown).

Error

Monitor

Over Current

Sense

Darlington

Po w e r

Driver

RT1

Over Temp.

Protection

DIR

MOTOR +

MOTOR -

ENABLE

Motor O/P

ENABLE

ERROR

24V (HL)

SK2

Green

Red

Yellow

Polarity

Switching

Relays

(Gate)