Printer Control System Controlling the Power Supply Here, you will learn about the source of the DC power used to operate the printer unit and how it is supplied.

Controlling the Power Supply

　

○Purpose : Here, you will learn about the source of the DC power used to operate the printer unit and how it is supplied.

　

　

1. Outline

The machine’s power supply block generates DC power using AC power coming from an outside source.
The various types of DC power that have been generated by the power supply block are sent to individual loads of the printer unit as well as the reader unit and accessories.
In addition to the power supply block, the AC power sent to the machine is also supplied to various heaters (e.g., fixing heater).
The following is a diagram of the machine’s power supply block:

The control mechanisms associated with the power supply block are as follows; for details, click [GO] of the appropriate item:

　

No. Item Description Details 1 DC power supply generation Generates DC power used to operate the machine. 2 Power saving Limits power consumption of the machine if the machine is left unused for a period of time. 3 Protection Cuts off output voltage automatically in the event of an over-current or abnormal voltage on the power supply PCB. 4 Backup battery Serves as a backup source of power for various data in the event of a power outage or power plug disconnection (1 each on the main controller PCB and the DC controller PCB). - 1. DC Power Supply Generation a. Printer Unit    DC power is generated by the power supply block of the printer unit.     The generated DC power is sent to various loads of the printer unit as well as the reader unit and individual accessories.     Now, let’s identify the location of the printer unit where DC power is generated and see how it is supplied. 　 b. Printer Unit    The printer unit generates DC power using AC power that comes from an outside source.     Of the types of DC power supplied to the printer unit, 24V and 13V are generated by the printer power supply PCB.     5V and 3V are generated by the controller power supply PCB using 24V.     The controller power supply PCB serves to supply 24V, 13V, 5V, and 3V to the various loads of the printer unit.     The DC power supplied to accessories is handled by the accessories power  supply PCB.     The following shows how different types of power are supplied to individual loads and the functions of the power supply PCB: 　 ●Distribution of Power ●Functions of the Various PCBs Item Description Printer power supply PCB Generates DC power (24V, 13V). Supplies DC power to the controller and the cassette pedestal. Accessories power supply PCB Supplies DC power to the side paper deck, buffer path, and finisher. Main switch (SW1) Turns on/off the AC power to the AC driver PCB. Door switch (SW2) Turns on/off 24VU1 to the DC controller PCB. Leakage breaker Cuts off power in the event of a fault. Heater PCB (option) Turns off/on power to the cassette heater, reader heater, and deck heater by means of a heater switch (SW5). High-voltage power supply PCB Generates various types of high voltage. AC driver PCB Supplies AC power to the printer power supply PCB, accessories power supply PCB, and uninterruptible power supply PCB. Drives the fixing heater. Controller power supply PCB Generates DC power (5V, 3.3V). Supplies DC power to the 3 way unit-A1, fax board, main controller, DC controller PCB, and high-voltage power supply PCB. Uninterruptible power supply PCB Generates and supplies uninterruptible power (3VB). This power supply PCB is independent of the printer power supply PCB, and the fact helps limit the PCBs that operate during sleep to a minimum, making 1W sleep possible.

　

The machine is equipped with a door switch (SW2) to make sure of safety when its door is opened
SW2 is found in the 24VU1 line that goes through the DC controller, and is designed to go off when the right cover or the front cover is opened.
When the switch goes off as the door is  opened, the 24VU1 supplied to the high-voltage power supply PCB will also go off at the same time so that the user will not suffer an electrical shock should he touch the inside of the machine.
The DC controller monitors the state of SW2, and will issue a message to indicate that the door has been opened.

　

　

c. Reader Unit

The reader unit generates 5 VDC and 3.3 VDC using 24 VDC and 13 VDC supplied by the printer unit.

The following is a list of uses of the individual types of DC power and a diagram of the system:

24VDC: used to drive motors

13VDC: used to turn on the CIS LEDs

5VDC:  used to drive sensors

3.3VDC: used to drive IC on reader controller; used to drive CCD of CIS

2. Power Saving Mechanism (sleep)

a. Outline

A power saving function is used to limit the amount of power consumed when the machine is not in use.

The machine’s power save mechanism consists of the following 3 modes that are switched over to suit the state of the printer unit.

　

Mode Description Sleep standby The control panel is in a sleep state, and a job (e.g., PDL) other than COPY has occurred. Seep 1 The control panel is in a sleep state, and fixing temperature control is not being performed. The controller is in operation. Sleep 3 The CPU of the controller is not operating (1W sleep), and only the uninterruptible power supply remains supplied with power.

　

The following table shows how the machine is supplied with power in the foregoing sates:

　

Mode Reader Printer Controller Control panel Fixing assembly Fax Diagram of power supply Sleep standby yes yes yes no yes yes Sleep 1 yes yes yes no no yes Sleep 3 no no yes/no no no yes/no Standby yes yes yes yes yes yes

yes: supplied with power yes/no: partially supplied with power no: not supplied with power

Sleep standby

Sleep Standby

　

In this state, only the control panel remains off.

Sleep 1

　

In this state, both the control panel and the fixing assembly remain off.

Sleep 3

　

In this state, all but the uninterruptible power supply circuit and some part of the main controller remain without power.

Standby

　

In this state, the machine is in standby, and all loads remain supplied with power.

Previous models offer sleep states 1 and 2; this model, on the other hand, has sleep states 1 and 3 (instead of 2).

In previous models, the level of power consumed in sleep 2 is 5 W; in this model, the level is limited to 1 W, thanks to the limit imposed on the number of PCBs that remain powered.

　

b. Mode Shifts

A shift to a different mode is initiated in response to a press on the control panel power switch or the use of user mode.

1) Shift to Sleep 1

A shift to sleep 1 starts in response to the following:

∙ when the machine is in a standby state, the control panel power switch is pressed.

∙ in user mode, the power consumption is set to ‘low’ for sleep states.

2) Shift to Sleep 3

A shift to sleep 3 is determined with reference to the length of time passing after a shift has been made to sleep 1, and it cannot be changed from outside. 

When 10 min pass after the shift to sleep 1, the machine automatically shifts to sleep 3.

　

3) Shift to Sleep Standby

A shift to sleep standby is initiated automatically in response to the introduction of a job.

When a job ends, the machine shifts to sleep 1 regardless of the type of state it was in previously. (It shifts to sleep 1 even if the previous state was sleep 3.)

　

4) Shift to Standby

Recovery from sleep to standby is executed in response to a press on the control panel power switch.

There is no other means of causing the machine to shift to standby.

●Diagram Showing Shifts to Sleep Mode

　

3. Protective Mechanism

A protective mechanism is used to protect PCBs in the event of an over-current or over-voltage.

If a fault (e.g., short circuit) occurs in any of the loads of the machine and, as a result, an over-current or over-voltage flows, the power supply PCB could well suffer damage if left unattended. The machine’s DC power supply PCB and the power supply PCB used for accessories are equipped with an over-current protective mechanism and over-voltage protective mechanism for protection by automatically cutting off the output voltage.

In the event of a fault in its power supply, the following will be true of the machine:

　

a. Fault in 3 VB (uninterruptible power supply)

All power will be cut off.

　

b. Fault in a Power Supply Other Than 3 VB

All power except 3VB (uninterruptible power supply) will be cut off.

　

If a fault has occurred in 3VB (uninterruptible power supply), turn off the main power supply switch of the printer unit, remove the cause of activation (of the protective circuit), and replace the uninterruptible power supply PCB. (The fuse of the PCB is mostly likely to have blown.)

In other cases, turn off the main power switch of the printer unit, remove the cause of activation, and leave the machine alone for about 3 min or more; then, turn back on the power so that the protective circuit will reset itself.