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Description  |
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BACKGROUND OF THE INVENTION
The present invention relates to a map display system for guiding a vehicle
such as a car.
Various suggestions have been made about a map display system of this type
in the prior art.
An example is disclosed in Japanese Patent Laid-Open Publication No.
164583/84 invented by the present applicant. In this system, map pattern
data providing the basis of display of roads and the like on a display
screen and character data providing names of municipalities, roads and the
like are both stored as code data, so that with the driving of the
vehicle, map patterns and descriptive characters are indicated on the
display screen automatically or by the operation of the driver.
Indication of all character data included in a given map area on display
makes it difficult to see the map as a great number of display data
characters are involved. For this reason, there is needed some display
limitation.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a map display system in
which character data are provided as a data base independent of data for
preparing a map, so that characters are displayed always in the same size
regardless of the scale of the map which may be enlarged or reduced by a
map display designation on the one hand, and the characters are made
easily recognizable on the other hand. That is the interval between
characters is kept constant.
In order to achieve the above-mentioned object, according to the present
invention, there is provided, as shown schematically in FIG. 1, a map
display system comprising map data memory means for storing map-forming
data required for display of each display area and character data
corresponding to each of said areas; display area designation means for
reading the map-forming data corresponding to a specified display area
from said map data memory means and producing a display area instruction;
display character designation means for selecting only the character data
corresponding to defined components constructing the specific display area
designated by said display area designation means and producing a display
character instruction; and display means for displaying the map of the
specified display area in response to the display area instruction from
said display area designation means and displaying characters in response
to the display character instruction from said display character
designation means in said display area.
A map display system further comprises character form control means for
maintaining the size of the characters displayed on the display means and
the interval between characters to a fixed level regardless of the display
scale of the display area.
A map display system further comprises number-of-characters control means
for changing the number of characters displayed on the character display
means in accordance with the scale of the display area.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram showing a configuration of the present invention.
FIG. 2 is a block diagram showing an embodiment of the present invention.
FIG. 3 shows a data configuration of character data.
FIGS. 4 and 5 are flowcharts for explaining the processing operation of a
CPU.
FIGS. 6 to 11 are diagrams showing forms of map and display screens for
explaining the transfer of screen display forms.
FIG. 12 is a flowchart showing displays of display data according to type
codes and designation codes of descriptive data.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A configuration of an embodiment of the map display system according to the
present invention is shown in FIG. 2. In this map display system, a system
1 includes a well-known microcomputer having a CPU 1a, a ROM 1b, a RAM 1c,
an input port 1d and a common bus 1e, and a CRT controller 1f. The system
further comprises input means including a direction sensor 2 for detecting
the direction in which the vehicle is running, a distance sensor 3 for
detecting the distance covered by the vehicle, a control panel 4 operated
by the driver, and a reader 5b with a replaceable magnetic disc 5a, which
input means are electrically connected to the system proper, and output
means including at least a CRT display 6 electrically connected thereto
for displaying map patterns such as roads and characters.
The direction sensor 2 includes an annular permalloy core, an excitation
coil and two coils intersecting each other at right angles, and produces a
direction signal for detecting the vehicle running direction against the
earth's magnetism on the basis of the output voltage of the two coils.
The distance sensor 3 detects the revolutions of a speed meter cable
indirectly as an electrical signal through a reed switch, a magnetically
sensitive element or a photoelectric cell, or detects the revolutions of
the output shaft of the transmission as an electrical signal in a similar
manner, thereby producing a distance signal used for computing the
distance covered by the vehicle.
The control panel 4 includes at least a switch (not shown) for supplying
and interrupting power to the map display system from a battery mounted on
the vehicle, enlargement and reduction keys (not shown) which are operated
by the driver for designating an enlarged or reduced display of the map,
and a display key (not shown) which is operated by the driver for
designating the display of a description on the screen of the CRT display
6.
The magnetic disc 5a stores map patterns as pattern data and character data
corresponding to appropriate geographic points on the map as code data.
Assume that characters "ABC City", "DEFG", "HIJKL" and "MNO" are to be
displayed, for example. As shown in FIG. 3, each of the character data is
made up of a set of data elements including a display character code, an X
coordinate of the position, a Y coordinate of the position, a pilot code
display scale, a single-character display scale, a double-character
display scale, a three-character display scale, . . . . . , a n-character
display scale.
The ROM 1b of the system proper has a program stored therein by which the
CPU 1a executes the processes shown in the flowchart of FIG. 4.
The CPU 1a repeatedly executes the processes (1) to (12) described below.
(1) Whether or not the enlargement key is turned on (step 101 in FIG. 4) is
decided.
(2) If it is decided that the enlargement key is turned on, the enlargement
process is executed (step 102). The specific operation of the enlargement
process will be described later.
(3) After execution of this enlargement process, or if it is decided that
the enlargement key is not turned on by the step 101, then it is decided
whether or not the reduction key has been turned on (step 103).
(4) If it is decided that the reduction key has been turned on, the
reduction process is executed (step 104).
(5) After execution of the reduction process or if it is decides at step
103 that the reduction key has not been turned on, then the direction
signal from the direction sensor 2 and the distance signal from the
distance sensor 3 are received to compute the present position of the
vehicle in a well-known manner (step 105).
(6) The present position obtained by the above computation is compared with
the geographic point corresponding to the descriptive data, that is, the
descriptive point thereby to decide whether or not the present position
coincides with the descriptive point (step 106).
(7a) If it is decided that the present position does not coincide with the
descriptive point, the process is passed to the computation of the present
position (step 105).
(7b) If it is decided that the present position coincides with the
descriptive point, on the other hand, the description based on the
descriptive data corresponding to this descriptive point is displayed on
the screen of the CRT display 6 through the CRT controller 1f or the
description on display on the screen of the CRT display 6 is erased (step
107).
(8) It is decided whether or not the abovementioned description is the one
required to be stored in the RAM 1c, such as a radio broadcasting station
with the receiving frequency thereof or a telephone number of JAF (step
108).
(9) If it is decided that the description is the one to be stored, the
particular descriptive data is stored in the RAM 1c (step 109), and the
description, after being displayed for several seconds on the screen of
the CRT display 6 through the CRT controller 1f, is erased (step 110).
(10) After the end of the process of the step 110, or after it is decided
at step 109 that the description involved is not the one required to be
stored such as "Narrow road" or "Beware of falling stone", then it is
decided whether or not the display key has been turned on by a signal from
the display key on the control panel 4 (step 111).
(11) If it is decided that the display key has been turned on, the
description based on the descriptive data stored in the RAM 1c is
displayed on the screen of the CRT display 6 through the CRT controller 1f
(step 112).
(12) After execution of, the process of the step 112, or if in the step 111
it is decided that the display key has not been turned on, then process is
passed to the step 101 for deciding whether the enlargement key has been
turned on or not.
Essential parts of the aforementioned enlargement processes are
specifically shown in FIG. 5. These processes will be explained below.
(1) A display scale coincident with the scale designated by the enlargement
key operation is determined (step 1021). In other words, it is decided
whether or not the designated scale coincides with the pilot code display
scale, the one-character display scale, the two-character display scale,
the three-character display scale, . . . . . or the n-character display
scale, or it does not coincide with any of the display scales. This step
1021 is executed only for one of a plurality of display characters once
each time of process.
(2a) If the designated scale fails to coincide with any of the display
scales, the positional coordinate (x, y) determined in advance in
correspondence with the display character is transferred to the display
screen, and the mark "X" or ".DELTA." is attached to the coordinate
position (step 1022).
(2b) When the designated scale coincides with the pilot code display scale,
on the other hand, the pilot code is displayed at the display coordinate
position in the same manner as above (step 1023). At the same time, a
correspondence table is displayed at the upper right corner of the screen
as viewed from the operator (step 1024). This correspondence table is
displayed in such a form as "a: ABC City" if the display characters are
"ABC City" and the pilot code is "a", for example.
(2c) If the designated scale coincides with the i-character display scale,
such as the double-character display scale, for instance, it is decided
whether these two characters coincide with all the display characters
(step 1025). Assuming that the display characters are "ABC City", for
instance, the characters involved are seven in all, and therefore it is
decided that they fail to coincide with each other, so that the display
color is changed (step 1026). This display color change is a process for
changing the color of the characters to be displayed next. After this
display color change or the step 1025 decides that all the characters
coincide, the characters to be displayed are displayed in color at the
display coordinate position (step 1027).
(3) After the process of (2a), (2b) or (2c) above, it is decided whether or
not the process has been completed for all the display characters (step
1028), and if all the data is not completely processed, the step 1021 is
executed again for the next display characters. If all the data is
completely processed, by contrast, this routine is left.
In parallel to this enlargement process, the form of display screen
described below is achieved according to the designated scale.
Specifically, in the case of a map comprising patterns and characters as
shown in FIG. 6, assume that the designated scale is minimum, that is,
display of the whole map is designated. In view of the fact that roads are
so densely located that a character display thereof is not legible, only
the marks "X" and ".DELTA." are attached at the display positions based on
the coordinate (x, y) as shown in FIG. 7. In the case of a designated
scale a rank higher, the pilot code "a" is displayed only for ABC City,
together with the correspondence table "a: ABC City" at the upper right
corner at the same time as shown in FIG. 8. Further, on the other hand,
"AB" alone of "ABC City", "DE" alone of "DEFG" and "HIJ" alone of "HIJK"
are displayed as shown in FIG. 9, while at the same time displaying the
whole of "MNO". If the designated scale is a greater rank, the whole of
"ABC City" and "HIJKL" and "DEF" alone of "DEFG" are displayed as shown in
FIG. 10. As can be seen from these figures, the interval between adjacent
characters remains the same regardless of the scale of the map.
Now, explanation will be made of the manner in which the display form of
the screen of the CRT display 6 undergoes a change with the progress of
the vehicle with reference to the steps 105 to 112 in the flowchart of
FIG. 4 described above.
The roads displayed on the screen of the CRT display 6 have descriptive
points (P.sub.2, P.sub.3, P.sub.4, . . . ) for displaying service data of
various types, so that sentences of the descriptive data are displayed on
the screen of the CRT display 6 when the vehicle passes each descriptive
point.
(1) When the vehicle having passed the point P1 shown in FIG. 11 reaches
the descriptive point P2, the data "Beware of falling rock" is displayed
at a part of the screen, such as at the lower part thereof.
(2) Subsequently when the vehicle having passed the point where he was
warned against falling rock reaches the descriptive point P3, the display
"Beware of falling rock" is erased.
(3) Subsequently when the vehicle reaches the descriptive point P4, the
telephone number of JAF (corresponding to AAA) such as "JAF
.DELTA..DELTA.- 0000" is displayed for several seconds.
(4) Subsequently when the vehicle reaches the descriptive point P7 through
the points P5 and P6, the receiving frequency such as "A broadcasting
station xxxxx KHz" is displayed for several seconds.
(5) After that, when the vehicle reaches the descriptive point P9 through
the point P8, the receiving frequency "B broadcasting station 0000 KHz" is
displayed for several seconds.
(6) Then, when the vehicle reaches the descriptive point P13 through the
points P10, P11 and P12, "Narrow road" is displayed at a part of the
screen.
(7) After that, when the vehicle reaches the descriptive point P14 through
the narrow road, the display "Narrow road" is erased.
As described above, in the case where a vehicle makes progress as shown in
FIG. 11, the display form of the screen changes as specified from (1) to
(7) with the progress of the vehicle. However, if the display key of the
JAF telephone number or other key is operated after the vehicle has passed
the descriptive point P4, for instance, the telephone number of JAF or the
related data, as the case may be, is displayed by the operation of the
display keys.
The steps 106 to 112 in the flowchart of FIG. 4 will be explained more in
detail below.
As shown in Table 1, the display data, designation codes and type codes are
stored in the magnetic disc 5a in correspondence with the coordinate data
of the respective descriptive points (P.sub.2, P.sub.3, P.sub.4, . . . ).
TABLE 1
______________________________________
DESCRIPTIVE POINT DATA
Position of
descriptive Type Designation
point Display data code code
______________________________________
P2 (x.sub.p2, y.sub.p2)
Beware of falling
1 1
rock
P3 (x.sub.p3, y.sub.p3)
"Beware of falling
1 2
rock" cancelled
P4 (x.sub.p4, y.sub.p4)
JAF .DELTA..DELTA.-OOOO
2 3
P7 (x.sub.p7, y.sub.p7)
A broadcasting sta-
3 3
tion xxxx KHz
P9 (x.sub.p9, y.sub.p9)
B broadcasting sta-
3 3
tion xxxxx KHz
. . . .
. . . .
. . . .
P13 (x.sub.p13, y.sub.p13)
Narrow road 1 1
P14 (x.sub.p14, y.sub.p14)
"Narrow road" 1 2
cancelled
______________________________________
DESIGNATION CODES:
1: Data displayed while a caution instruction is issued.
2: Data for designating the cancellation of the data on display. Displaye
for several seconds.
3: Data displayed for several seconds and stored the RAM data. This data
becomes an object of operation display.
TYPE CODES:
1: Caution data
2: JAF data
3: Broadcasting station data
The descriptive data shown in Table 1 are processed in accordance with the
flow chart shown in FIG. 12. In the flowchart of FIG. 12, the display data
is displayed and stored in the RAM 1c in accordance with the designation
code and the type code of each descriptive data. The caution data with the
type code of "1", for instance, is not required to be displayed after the
vehicle has passed the particular point, and therefore is not stored in
the RAM 1c. As to the JAF data or the broadcasting station data with the
type code of "2, 3", however, they are stored in the RAM 1c, since the
telephone number of JAF or the receivable frequency of the broadcasting
stations is necessary in case of emergency even after the particular
descriptive point has been passed. When the user operates the display
keys, therefore, the descriptive data is read out and displayed from the
RAM even after the particular descriptive point has been passed.
Storage addresses corresponding to each descriptive data are predetermined
in the RAM, and they are rewritten as the latest data each time the
descriptive points are passed.
In the case where the data in the RAM is displayed at step 112, only that
data with the type code of "2" or "3" is picked up from Table 1 and
displayed. The display keys may be adapted for displaying each type code
each time of operation thereof.
* * * * *
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