ELECTRICAL SYSTEM
L3540-II, L4240-II, L5040-II, L5240-II, L5740-II , WSM
9-M5
2. ELECTRONIC CONTROL PANEL
[1] SYSTEM OUTLINE AND ELECTRICAL CIRCUIT
(1) System Outline
The Electronic Instrument Panel (Intellipanel) adopted in the L40 series tractors consists of an 8-bit CPU
*1
,
sensors and input devices, memory devices such as RAM and ROM, and others. The CPU does
multiplex-communication
*2
with ECU (Electronic Control Unit) and various sensors, switches and other related
devices in order to give the functions that accurately and timely provide an operator with various information
necessary for tractor operation. The contents include corrective procedure in case of an erroneous operation,
precautions, and various alerts. If the tractor gets in trouble, a problem location, for example, is displayed with a
message (sign) on the liquid crystal display or indicated with a monitor lamp.
The messages are displayed with segments, which gives approximately 200 patterns.
In the liquid crystal display (LCD)
*3
, characters appear over reflected illumination, and are always back-lit by a
small yellow lamp while the main switch is "ON".
*1
CPU
This Central Processing Unit is the core part of computers that controls the input/output devices to receive data,
processes the data, and sends out the computing results.
The CPU comes in different types: 8 bits, 16 bits, 32 bits, etc., according to the number of bits as the unit of internal
data processing. In general, the larger the number is, the higher the performance is.
*2
Multiplex communication
In multiplex communication, just one transmission (signal) line is effectively used to send and receive signals for
digital transmission. In data communication, the transmission capacity of the line and the capacity of signal
transmission/reception are represented by the number of bits that can be transmitted or received for one second.
When the capacity of the transmission line is extremely larger than the ability of the transmission/reception performed
by a terminal device, signals from plural terminals can be transmitted by means of time-sharing and multiplexing of
one transmission path.
The merits of multiplex communication are as follows:
1. It permits high-performance control that allows three units to share information from sensors and information
required for control.
2. It provides the smaller number of wire harnesses.
3. It allows each control unit to independently control the connected devices if communication should fail for some
reason and become impossible.
*3
Liquid Crystal Display
Liquid crystal display is a displaying device that uses the characteristic of liquid crystal, in which the application
of voltage triggers the molecules to change their orientations. The principle of indication is that when a voltage is
applied on a liquid crystal sandwiched between two glass plates, the direction of molecules changes, with the
resultant variation of the oscillatory direction of light that penetrates the liquid crystal. The set-up of a polarizing plate
makes light go through or get blocked according to a change in voltage. Since the use of only the polarizing plate
results in peculiar color, the film to counteract colored light is superimposed. However, the liquid crystal it self does
not generate light, so it is back-lit by a fluorescent tube, for example, which makes the display easy to read in a dark
space.
9Y1211167ELM0006US0
(1) Liquid Crystal Display (LCD) (2) Electronic Instrument Panel
(Intellipanel)
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