Theory of Operation Hardware Logical View
8-4 PageWriter TC 70 Cardiograph Service Manual
Display
The PageWriter TC70 cardiograph display is 1024 x 768 pixels, up to 65536-color TFT LCD
with backlight. All display functions are handled by the main control board using the SM501
(Silicon Motion) graphics accelerator chip.
Patient Interface Module (PIM)
The PIM is a PXA270-based WinCE subsystem that is connected by the USB to the main
control board. It provides real-time data acquisition of ECG signals from electrodes connected
to the patient.
Printer Control (FPGA)
All data printing is handled by the main control board. The printer control is an Altera
FPGA-based control circuit. It accepts printable data, provides basic bitmap imaging
operations, and controls the printer head and motor.
Battery (Lithium Ion)
The PageWriter TC70 cardiograph uses two battery packs. Each battery is a lithium ion,
11.1-volt, providing 7.2 amp-hours of current when fully charged.
Keyboard and Buttons
The PageWriter TC70 cardiograph includes a laptop-format, PS/2, sealed, full-key action
keyboard. Also included are three function buttons, used to turn the cardiograph on and off, for
patient ID input, and ECG capture. These three function buttons are designed to support the 1-
2-3 ECG capture operation and have LED backlights to illustrate their current status.
The keyboard function includes a keyboard matrix, a PS/2 encoding chip on an interface
board, and is managed through standard Win CE device drivers.
Touch Screen
The PageWriter TC70 cardiograph includes a 5-wire resistive touch screen in front of the LCD
panel. The touch screen provides access to all of the cardiograph features. Users simply touch
the buttons on the screen to open the different screens and to perform different functions. The
touchscreen is controlled by WM9712 (Wolfson) on the main board to sense the touched
position, while application software responds accordingly in different screens.
LAN Interface
The PageWriter TC70 provides standard LAN capability through a LAN91C111 (SMSC)
10/100M LAN controller. The PageWriter TC70 cardiograph communicates with
TraceMasterVue ECG Management System through the LAN interface.
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