ITW Diagraph IJ3000, Operation Manual, Page: 64 / 94

Integrated Valve
Appendix B: Theory of Operation
Page 56 of 86 5760-107 Operations Manual Rev C
Encoder
The encoder determines the time period between the printing of individual columns, or the
print speed. As a product's speed increases, the time period between columns must
decrease, that is, the print speed must increase, to maintain consistent column-to-column
spacing. The IJ3000 has two encoder options, external and internal. Use the external
encoder where the conveyor speed fluctuates. You can use the internal encoder when the
conveyor speed is constant.
The
external encoder
is a 5VDC, 1024 pulses per revolution optical encoder. The
encoder's wheel is sized such that the encoder outputs 100 pulses per inch of product
travel. The external encoder plugs into the Print Head Interface Board (J4), and its signal
goes to the FPGA where it is used to time the sending of column data to the print head.
The internal encoder signal is a constant frequency pulse stream generated on the Print
Head Interface Board. A programmable counter circuit in the FPGA divides the board's 16
MHz clock by a value calculated from a line speed entered during system setup. When the
user selects the internal encoder, a switch in the FPGA disconnects the external encoder
signal from the print timing circuits and connects the output from the counter circuit.
Power
One or two 15VDC, 70 watt desktop power supplies provide power to the IJ3000 and all of
its attachments. Power enters the IJ3000 through J3 on the Print Head Interface Board(s).
A system with a single interface board has one power supply; two interface boards require
two power supplies.
On each Print Head Interface Board, 15V is routed to the photosensor connector (P2) and
the print head connector (P1) through normally energized relay K1. An over voltage detec-
tion circuit de-energizes K1 and removes power from the print heads and photosensor
should the voltage exceed 18V.
• Battery Backup
A 3V battery on the CPU Board (BT1) maintains the contents of system SRAM and keeps
the real time clock running during power outages or when the IJ3000 is not plugged into a
power outlet.
• Power Distribution
Refer to the illustration below. 15V from the first Print Head Interface Board only (the one
immediately above the CPU Board) is routed to the CPU Board, where it is stepped down
to the 12VDC and 5VDC used to power the rest of the system. 12V goes to the Display
Interface Board where it powers the backlight inverter, and 5V is distributed throughout the
CPU Board, to the Display Interface Board, and to the Print Head Interface Board(s).
Please note that power is applied to the IJ3000 even when it is "turned off." When turned
off using the OFF button on the keyboard, the IJ3000 enters a sleep mode where it
responds to nothing but the ON button. All voltages are present while sleeping. The only
way to completely remove power is to pull the plug.
15V in
15V in
PRINTHEAD INTERFACE BOARD #2
PRINTHEAD INTERFACE BOARD #1
CPU BOARD
DISPLAY INTERFACE BOARD
15V to printheads, photosensor.
5V to encoder.
15V to printheads, photosensor.
5V to encoder.
5V, 12V
5V
15V
IJ3000 POWER DISTRIBUTION