Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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DISPLAY SYSTEM FOR AIRPLANE COCKPIT OR OTHER VEHICLE
This application is a divisional of Canadian Patent Application No. 2,303,490
filed
on December 2, 2004.
BACKGROUND OF THE INVENTION
1, F IELP OF THE II11VENTION
The present invention relates generally to display systems for airplane
cockpits or
other vehicles, and more particularly, to a rear projection digital display
system which
allows a high level of infornzation to be selectively displayed regarding such
data as travel
path, travel conditions, vehicle condition, geographical conditions, and
hazard or
obstruction warnings.
2. DESCRIPTION OF THE RELATED ART
The layouts of coclcpits for airplanes are regulated by the FAA (Federal
Aviation
Administration) in the United States. The SAE (Society of Automotive
Engineers), which acts as a
standards writing/recommending body to the FAA, has issued standards for
aircraft instnuzients
which are adhered to in aircraft construction. For example, the 3'ATI slot
standard, which
is an ARINC (Aeronautical Radio, Inc.) standard, has been complied with in the
vast
majority of all aircraft in use today. This standard was developed when
electro-mechanical
display devices, such as HSI (Horizontal Situation Indicator), were the norm,
and only
allows a panel area of 3" x 3" in dimension.
With the advance of digital technology, there has been a need in the industry
to
replace these displays with digital versions, to provide increased
reliability, accuracy and
more functionality. However, these planes cannot be easily retrofitted with
digital
equipment that require a bigger screen, and the required 3 x 3 panel has
conventionally
proven to be too small for digital displays. The 3" x 3" display has been a
major
impediment to the development of such a digital display,
First, standard direct view LCDs are not mass produced in this size, and
therefore a
specially made LCD for 3" x 3" can cost as much as $10,000 each to produee.
Furthermore, due to the construction of the direct view LCD, the outer
perimeter of the
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d,evice cannot be used to display information, as it is used by the drive
electronics. As a
result, the 3" x 3" LCD typically produces a display area of only 2.3" x 2.3".
This reduced
display area impedes the ability to put enough information on the display for
it to be
useable for many functions.
A second problem addressed by the invention is the growing demand in the
avionics industry for more sophisticated "situational awareness for safety"
(SAS)
technology. This refers to technology which provides the pilot with more
easily
understandable and more comprehensive information about the immediate
surroundings,
and any hazards which may be present.
For example, in 1996, there were 246 general aviation airplane crashes in the
United States. Of these crashes, 42 were controlled flight into terrain
(CFIT). That is,
situations in which the airplane was flown into an obstruction such as a
mountain, an
antenna or the ground under control of the pilot. Typically these instances
occur when
visibility is very low and the pilot is off course. As a result, the pilot is
unaware of the
natural obstructions in flight path because the display devices only provide
information on
the desired flight course.
It is believed that if the present invention had been available for these
planes, a
large number of these accidents would have been prevented, and hundreds of
lives saved.
Thus, there is a need in the industry for (1) technology to effectively
collect data on
surrounding structures even when the pilot is off path, and (2) hardware to
display this
information in a simple and direct manner to the pilot, preferably using
digital instruments.
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SUMMARY OF THE INVENTION
In accordance with one aspect of the present
invention, there is provided a method of warning an airplane
pilot of dangerous proximity to the ground, comprising: (a)
receive G.P.S. data providing the plane's current
geographical location; (b) comparing the received G.P.S.
data with topographical data stored in a computer memory and
determining whether the plane is within a predetermined
threshold range of the ground; and (c) if the plane is
within the predetermined threshold, issuing a visual warning
to the pilot.
In accordance with a second aspect of the present
invention, there is provided a method of warning an airplane
pilot of dangerous proximity to the ground using a rear
projecting display device, comprising: (a) receiving G.P.S.
data providing the plane's current geographical location;
(b) comparing the received G.P.S. data with topographical
data stored in a computer memory and determining whether the
plane is within a predetermined threshold range of the
ground; and (c) if the plane is within the predetermined
threshold, projecting a visual warning on a screen using a
rear projection system.
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geographical area in database form. The device correlates the G.P.S. and
topographical
data to determine the location of the aircraft, and any obstacles in the
flight path or
surrounding area. In addition, data from the flux gate and gyro, which
indicate the current
location of the airplane, are used to determine the flight path of the
aircraft. Other
navigational devices (e.g, VOR (Very High Frequenc), Omnidirectional Range))
may also
be used to determine heading. From this information, upcoming obstacles are
determined
from the DOD (Department of Defence) topographical data, and are displayed to
the pilot.
In certain embodiments of the invention, different types of information are
selectively displayable on the system. To avoid clutter and ease of
understanding, user
inputs are provided to allow the pilot to selectively turn on or off the
display of certain
information. For example, as the pilot is approaclung the runway for a
landing, and is
within visible range of the runway, the pilot may turn off the rearward view
or
navigational aids not associated with the approach to the runway.
In addition, it should be noted that while the present invention is a well
suited for
use in the avionics cockpit display, it is equally applicable to other
vehicles.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is block diagram of the components of one embodiment of the present
invention.
Fig. 2 is a cross section of one embodiment of the invention.
Fig. 3A is a block diagram of one embodiment of the video display system of
the
invention.
Fig. 3B is a more detailed block diagram of the mirror and LCD system of the
invention.
Fig. 4 is a block diagram of one embodiment of the sensor input system of the
invention.
Fig. 5 is a program flow chart of the operation of one embodiment of the
invention.
Fig. 6 is a flow chart of a subroutine for use in the program flow of Fig. 5.
Figs. 7A and 7B are representative display screens of one embodiment of the
invention.
Figs. 8A and 8B illustrate an embodiment of the invention for use in a 3ATI
slot.
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DETAILED DESCRIPTION
General Description
Fig. I is a block diagram of the overall system. The entire system is run by a
microprocessor 100 which may be the MPC 821 manufactured by Motorola. As will
be
explained more fully below, microprocessor 100 receives a plurality of the
sensor inputs
200 which may include, for example, G.P.S. information, flux gate data, gyro
data, etc.
The sensor inputs 200 are sampled and input to processor 100 in sync with
clock sync
signal 300. The microprocessor 100 receives clock sync signal 300 and
regenerates and
supplies it to the attached devices. Microprocessor 100 is also associated
with a non-
volatile memory 410, wluch may be a flash memory such as mode1208F800
manufactured
by Intel. This memory is used to store operational software, database
information, and
repetitive screen data as explained more fully below. Microprocessor 100 is
also
associated with volatile memory 420, such as DRAM (Dynamic Random Access
Memory), for
storing information used during operation, -and graphical infozmation for
driving the display
system. Typically, memories 410 and 420 each will have at least 4M bytes of
storage space.
Microprocessor 100 also controls rear projection system 500, which includes a
light source 510, LCD driver system 520, and a rear projection LCD 530, which
displays
data on screen 540. The LCD driver system 520 receives the graphical
information from
memory 420, which is programmed by the microprocessor 100. Microprocessor 100
programs the graphical data into memory 420 based on the data received from
sensor
inputs 200, and the user input conditions received from a user input device
600.
As is shown in Fig. 2, the entire device may be fitted into a 3ATT box. As
shown,
user input device 600 (Fig. 1) includes a plurality of buttons 900 and at
least one knob 910
which are selectively positioned so as not to obstruct screen 540 (not shown).
Referring to
Fig. 1, these devices are positioned within the instruments so as to avoid
crossing the light
path between light source 510, LCD 530 and the image path between the LCD 530
and
screen 540. The mechanical aspects of the present invention to achieve such a
compact
and unobstructed design will be explained more fully hereinafter.
Rear Projection LCD Display System
Fig. 3A is a more detailed block diagram of rear projection system 500 which
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i{lcludes light source 510, mirror system 532, LCD 530,LCD driver 522,
serializer 524 and
= ...:. _..._.
screen 540. A commercially available TFT (Thin Film Transistor) type LCD may
be used
for the image projection. Although any suitable projection LCD system may be
used, LCD
530 and mirror system 532 make up a filterless microlens-type rear projection
LCD. An
5 example of such device is the Sony model no. LCX019. The LCX019 has a
substantially
rectangular image generation area (active area) of 26.9mm x 20.1mm, which
provides an
approximately 4:3 aspect ratio image. The device may operate as follows: light
source 510
emanates white light, and mirror system 532 breaks up the light into three
components, R,
G, B, respectively along a first axis R, a second axis G, and a third axis B,
all three of
which are at an angle to one another. The light rays R, G, B impinge upon
individual
pixels of LCD 530 at discreet angles. In accordance with electrical signals
received from
LCD driver 522 and serializer 524, which are formulated in response to data
from
microprocessor 100 and the graphical data from memory 420, the individual
pixels of
LCD 530 are adjusted so as to collectively form a color image which is
projected along
optical axis X and on to screen 540. The LCD 530 may be updated at any desired
rate via
driver system 520, but preferably is updated at 30 frames per second. The
operation of the
LCD driver is described below.
A more detailed description of the light system of one embodiment of the
invention
is provided with reference to Fig. 3B. Lamp or other light source 510
generates white
light which is reflected off a first mirror 5322 and passed through a
condenser lens 5323 so
as to form a colliminated light beam which is then presented to a dichroic
lens system
5324. The system includes a wedge which has a top surface 5324A coated with a
dichroic
material which reflects red light and passes all other colors. The reflected
red is direct to
the LCD at 7E above the line normal to the LCD. The second surface 5324B of
the wedge
5324 reflects blue at OE to the normal and passes all other colors. Beneath
the wedge 5324
is a mirror 5325, which reflects the remaining green light -7E with respect to
the normal.
For sake of simplicity, this is illustrated in Fig. 3B with respect to only
one ray of light.
Of course, in operation all light presented to the wedge 5324 and mirror 5325
will undergo
similar separation. R, G and B light beams are then impinged upon LCD 530.
Following
the LCD 530, the formed image is passed through a projection lens system,
including
lenses 5326A and 5326B and projected on the screen.
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It should be noted that instead of a wedge, two separate mirror plates could
be
used. However, the wedge arrangement achieves the same results as a mirror
system,
while avoiding the necessity of light passing through up to four additional
surfaces (e.g.,
the green light would have to go through two extra surfaces on the way down
and two
extra surfaces on the way up). This allows for greater display intensity.
The LCD driver system 520 includes a digital to analog converter. The analog
data
is then input to the serializer 524, which is then input to LCD 530. The LCD
driver 522 is
refreshed from a graphics buffer which is in memory 420. This is done in
hardware. If
processor 100 stops updating the screen memory, the LCD driver 522 will still
continue to
pull the screen data in bursts from the graphics buffer in memory 420, and
keep the LCD
image updated. This means that processor 100 does not have to update the
screen graphics
data at a constant speed in order to eliminate flicker.
The screen data is updated in "push-pull" graphics buffers. This means that
while
a first buffer is used for LCD refresh, the processor software updates a
second buffer.
When the processor is done with the new update, it sets a "ready" flag and
changes the
start address for the LCD driver 522. This is called a"handoff" of the new
buffer. When
the LCD driver 522 is at the end of the current screen refresh period, it will
automatically
use the new buffer address, placing the newly updated graphics data on the
screen. The
LCD driver 522 also generates an interrupt in processor 100 which indicates
"handoff
complete" by resetting the "ready" flag and setting the address of the next
update buffer.
This flag/address indicates the free buffer and will be used by the main
program loop for
the next update.
A three buffer system may be used to accomplish this result.
1. Buffer currently displayed (read-only until hand-off to next buffer).
2. Buffer being painted (will become next displayed).
3. Buffer being cleared (will become next painted).
The use of a three buffer scheme allows the buffer clear operation to be done
by
direct memory access (DMA) which improves processor efficiency by allowing
processor
software execution to occur simultaneously with screen buffer clearing.
In order to increase system speed, repetitively displayed graphics, e.g.
background
graphics such as a compass pattern, are written only once and stored as
background scenes.
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Thus, instead of the buffer being cleared to black, the appropriate repetitive
scene is
copied via DMA into the buffer. This allows the paint procedures to add only
the
appropriate graphics on top of the repetitive scene.
Thus, the process of reading and writing three buffers (buffer 0, buffer 1,
and
buffer 2) is as follows:
1. Refresh the LCD screen with data from buffer 0.
2. Processor 100 and memory 420 cooperate to store a new graphic into buffer
1.
3. Processor 100 and memory 420 cooperate to store repetitive scene data in
buffer 2.
4. Refresh the LCD screen with data from buffer 1.
5. Write new scene data into buffer 2 to overlay repetitive scene data already
in buffer 2.
6. Store repetitive scene data in buffer 0.
7. Refresh the LCD screen with data in buffer 2.
It will be recognized that the above description is merely one example of how
the
LCD reading and writing and driving functions may be performed. It will be
clear to those
of ordinary skill in the art that many other types of memory and program
architecture are
possible to achieve similar results.
Sensor Inputs
The present invention receives a plurality of sense signals, which are used by
processor 100 to calculate various parameters such as current heading, height
off ground,
longitude and latitude positions, attitude of the aircraft, etc. As shown in
Fig. 4, a plurality
of signals 210 may be received from various sensors in the aircraft. The
signals 210 may
be fed into signal conditioning circuits 220 which in turn are fed into a 48
channel
multiplexor 230. The multiplexor 230 also receives a clock control sync signal
240. In
one embodiment, the clock control signal 240 is the A/C power supply of the
aircraft
which is 400 Hz. Use of the aircraft power supply of the clock signal is
advantageous to
sync multiplexor sampling to the A/C sensors, as sensors throughout the
aircraft may be
synched with processor 100 and the multiplexor 230 without the need for a
separate clock
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signal to be run throughout the aircraft. The use of a single multiplexor 230
also allows
.,, . _ ._.
use of a single A/D convertor 250 which inputs to microprocessor 100. Signal
inputs 210
include signals from the flux gate, the directional gyro, the G.P.S. receiver,
the ILS
receiver (instructional landing system) which provides for precision approach
guidance
and landing. As shown in Fig. 1, some inputs may be directly coupled to the
microprocessor 100 by serial input 250. For example, GPS data may be serial
input from a
GPS receiver. Or, data from the radar altimeter, which indicates the height of
aircraft
above the ground may be input by serial input. Depending on the priority level
of the data,
some of the inputs may be sampled once per cycle while others may be sampled
multiple
times per cycle through the multiplexor 230.
In some embodiments a 1600Hz sync signal is generated by "synching" off the
peak voltages and zero crossings of the 400Hz power supply signal. This allows
faster
sampling.
In addition to the above-described sensors, additional sensors such as a
lightening
sensor may be used. Indeed any navigational or other flight data sensor may be
used.
In certain embodiments of the invention, nonvolatile memory 410 will store a
database corresponding to a topographical map illustrating different obstacles
throughout a
given sector of the world based on longitudinal and latitudinal locations. The
sense data
which provides the plane's location such as a G.P.S. receiver, or a similar
type system will
be reviewed by the microprocessor 100 and correlated via a look-up table with
the
topographical data. As a result, microprocessor 100 will be able to determine
if any
obstacles are within the flight path of the aircraft or within the vicinity of
the aircraft. This
data, as explained below, can then be displayed to the pilot in a succinct
manner so as to
alert him of the possibility of hitting the obstacle.
Memory 410 also stores other database information, such as airport location,
runway data, magnetic north data, etc.
The present invention also provides a unique method of updating the database
information stored in memory 410.
As is well known in the art, database information such as airport location,
magnetic
data, etc., is updated on a regular basis. However, when these databases are
updated, they
have an effective date in which they will become applicable.
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Databases are updated by a regular maintenance procedure on the airplane. In
. ... . - ' . _
particular, a maintenance computer is attached to the onboard microprocessor
by, for
example, a serial port. The maintenance computer updates the database to
include the
effective data. However, the problem is where the maintenance on the airplane
is
performed prior to the effective date of the new data. In such situations, the
airplane has
conventionally been forced to store both the "old" database information as
well as the soon
to be effective database information, thereby doubling the amount of memory
required.
However, according to the present invention, the database is updated such that
only the
changed information of database is written into the memory. These changed
information
points are written into a portion of the memory referred to as continuation
data. Using the
database, microprocessor 100 will first read the anticipated data from the
regular portion of
the database, and then it will check the conditional memory section to see if
any changes
have been made in data currently being polled. If a change has been made,
microprocessor
100 determines whether the new effective date has taken place, and if it has,
it uses the
new data in the conditional memory; otherwise, it uses the old data. That is,
the
maintenance computer determines the contents of the database of the onboard
computer
and determines what data has changed. It only uploads the changed data. For
example, in
one embodiment the onboard memory contains data indicating the date of the
last update.
The maintenance computer checks this date and from this can determine what
data to add.
It should be noted that multiple changes may be made to a particular
datapoint, with each
change stored in the continuation memory. Of course, if desired the extra main
memory
may be re-updated and the continuation memory cleared.
This system has two main benefits. First, it reduces the amount of onboard
memory that is required, thereby reducing the cost of the device, and second,
it speeds up
the maintenance process of uploading the new data to the airplane as necessary
to upload
the changed data only.
Mechanical Imnrovements
As explained above, one of the aspects of the invention concerns maximizing
the
displayable area of the LCD screen. In one embodiment of the invention
directed to a
3ATI avionics slot, any blockage of the 3" x 3" screen can result in a useable
display area
which is too small for practical purposes. Accordingly, one aspect of the
invention is
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directed to the optimization of the placement of the user input devices, i.e.,
the user
. ~:. . .. __.
buttons and knobs which allow the pilot to control the symbolage displayed on
the device.
According to Fig. 2, a plurality of push buttons 900 are arranged along the
outer perimeter
of the display device. In addition, at least one turn knob 910 is set in the
bottom corner of
5 the display device, to avoid conflict with the viewing area. Knob 910 is
then connected
via a universal joint 920 to a rotary encoder 930. Alternatively, a flexible
shaft could be
used instead of a joint arrangement. The use of the universal joints solves
two problems.
First, it allows the placement of the knobs to be substantially parallel and
proximate to the
outer casing of the device. Second, it allows the shafts of the knobs to be
placed out of the
1 o optical path of the LCD.
The system of the present invention allows 8.4 square inches of a 3ATI panel,
which has 9.56 square inches of possible space, to be used for video display.
Thus, about
88% of the screen is utilized. According to the invention, preferably at least
70% of the
screen is used. More preferably, 75-88% is used, or at least 75%. Even greater
advantages
are achieved by using at least 80% of the screen, or at least 85%.
Accordingly, one
embodiment utilizes in the range of about 80% of the screen.
Operation
Referring to Fig. 5, the program flow of the present invention will be
described. In
step 700, the processor 100 receives the sent signals from sensor inputs 210.
This is done
as the multiplexor steps through each of the inputs. In step 710, the
microprocessor 100
polls the user input buttons, to determine the symbolage and various data to
be displayed
on the screen. In step 720, processor 100 calculates the required display
parameters, e.g.,
attitude of the plane, compass direction, and other such data based upon the
sensed signals
and the particular graphical modes selected by the user controls. In steps 730
to 750,
processor 100 calculates any "emergency" parameters, even if they were not
selected by
the user in step 720.
An example of such a subroutine is illustrated in Fig. 6. For example,
assuming
the user had the tetrain data and G.P.S. and topographical data functions of
the device
turned off, in step 810, the processor would review the sensed G.P.S. data. In
step 820, it
would receive the flux gate and gyro data. In step 830 it would use the data
from step 810
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and 820 to calculate the current location and attitude of the plane and its
present flight
. ...: . . . ._.
path. In step 840 it would look up the topographical data in memory 410
associated with
the location and flight path calculated in step 830 and determine the location
of any
obstacles. In step 850 the processor would determine if any obstacles are in
the current
flight path. If yes, it would write emergency graphical data to the next
buffer to be
displayed by the LCD. If not, it would proceed to step 860 and determine if
any obstacles
are located within a predetermined distance of the plane's current location or
flight path.
If yes, warning data would be written into the graphical buffer to next be
painted on to the
LCD. For example, if in step 850 an obstacle is found to be within the flight
path, it may
lo be written to the buffer so as to show up in bright red and flashing on the
next screen. If in
step 860 an obstacle is found within the predetermined location of the
aircraft, but not
directly within the flight path, a yellow or amber symbol may be displayed on
the screen
so as to advise the pilot to closely monitor the location of that obstacle.
In determining whether an obstacle is within the flight path, the system
considers
the altitude of the obstacle and the plane, as well as the current flight
path. For example, if
an obstacle is located at 1200 feet elevation, and the plane is currently
flying at 6000 feet,
a warning would not be issued, unless the plane was in a descending course
that would put
it on course with the obstacle.
Referring again to the main program flow of Fig. 5, in step 760 the processor
will
write the graphical data to the next buffer in memory 420 and in step 770
repetitive data is
written in the next plus 1 buffer. In step 780, the next plus 2 buffer is
cleared and in step
790 the process is looped back to the beginning and repeated.
DISPLAY SCREENS
Figs. 7A and 7B illustrate representative screens which may displayed using
the
present system. Fig. 7A illustrates a 360 degree view with graphical
representations of
man-made obstacles, as well as natural terrain obstacles. The current location
of the plane
is illustrated by a plane icon 1000. The current heading is illustrated as 240
degrees by
icon I 100 and the current flight course is illustrated by line 1200. A
natural terrain
obstacle is illustrated as icon 1300. Natural obstacle 1300 has an elevation
of 1670 feet,
which may be considered dangerously close to the plane's current elevation of
1220 feet.
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Furthermore, the current flight course may be considered dangerously close to
the natural
. .,:. ._ _. __.
terrain object 1300, therefore an alert would be generated. As a result, for
example, alert
icon 1400, as well as icon 1300 itself, flash in red or amber. In addition, an
audible alarm
may be sounded. Referring to the same figure, man-made obstacles 1500 are
represented
by inverted "V's" on the screen.
Fig. 7B is similar to Fig. 7A described above, except it is in "arc" or 90
degree
view, thereby only providing the pilot with a forward looking perspective. In
addition,
other graphical images may be presented on the display. For example, in Fig.
7B a non-
directional beacon 1600 is illustrated on the display.
As may be well appreciated by those of ordinary skill in the art any type of
navigational display may be presented on the display of the present invention.
Accordingly, the above-described examples are to be recognized merely as
illustrative and
not exhaustive of the scope of the invention.
CONSTRUCTION
Fig. 8A illustrates an example of the 3ATI slot as used in the invention. Fig.
8B is
a partial breakaway of the 3ATI slot with the rear projection system of the
invention
disposed therein. For simplicity, other components are not shown in the
figure.
While the invention has been described above with particular reference to an
avionics display system, it will be appreciated that it may be used in any
vehicle display
system. In particular, it is extremely well suited for freight and commercial
trains as well
as high-speed bullet train systems. Moreover, while the Avionics display has
been
disclosed with reference to the 3ATI system, it is clearly understood that it
may be used in
other slot sizes and its applicability is clearly pertinent thereto.
