U.S. patent number 3,659,283 [Application Number 04/823,406] was granted by the patent office on 1972-04-25 for variable size character raster display.
This patent grant is currently assigned to Applied Digital Data Systems, Inc.. Invention is credited to David Ophir.
United States Patent |
3,659,283 |
Ophir |
April 25, 1972 |
VARIABLE SIZE CHARACTER RASTER DISPLAY
Abstract
Apparatus for providing a raster display of static data. A
plurality of static data characters, for example in binary coded
decimal form, is passed, a character at a time, by a parallel to
serial converter to a read-only memory which converts each
character into 20 eight-bit scan lines and transfers one scan line
at a time to a video signal generator. The signal generator applies
each bit to a raster display output device. The high cyclic rate
results in the simultaneous display of all the static data
characters. If desired, the display size, color, or intensity can
be varied or the display can be caused to blink or flash, all on a
display line by display line basis.
Inventors: |
Ophir; David (East Patchogue,
NY) |
Assignee: |
Applied Digital Data Systems,
Inc. (N/A)
|
Family
ID: |
25238681 |
Appl.
No.: |
04/823,406 |
Filed: |
May 9, 1969 |
Current U.S.
Class: |
345/472; 315/379;
D18/26 |
Current CPC
Class: |
G09G
5/26 (20130101) |
Current International
Class: |
G09G
5/26 (20060101); G06f 003/14 () |
Field of
Search: |
;340/324.1,324A |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Trafton; David L.
Claims
What is claimed is:
1. Apparatus for generating from a first plurality of coded input
data character signals a television compatible composite video
output signal for application to a television receiver to provide a
visible display of a first plurality of data characters in a second
plurality of data lines, each data line formed of a third plurality
of scan lines, each scan line including a fourth plurality of data
bits, said apparatus comprising:
a. clock means for generating clock pulses of a first
frequency;
b. first counting means connected to said clock means and
responsive to said clock pulses for counting scan lines and
providing an indication thereof;
c. second counting means connected to said clock means and
responsive to said clock pulses for counting display lines and
providing an indication thereof;
d. third counting means connected to said clock means and
responsive to said clock pulses for counting characters in each
display line and providing an indication thereof;
e. gating means having an output and having a first plurality of
inputs adapted for connection to a first plurality of data sources
for receipt in parallel therefrom of a first plurality of coded
input data characters, said gating means having further inputs
connected to said second and third counting means and in response
to display line number indications and character number indications
sequentially providing said first plurality of coded input data
character signals as a coded output data character signal;
f. decoding means connected to said gating means and to said first
counting means and responsive to said coded output data character
signal and to scan line number indications for decoding said coded
output data character signal into a fourth plurality of data bits
representative of the indicated scan line of the output data
character of said coded output data character signal;
g. video signal generator means connected to said decoding means
and to said first, second and third counting means and in response
to said fourth plurality of data bits and to scan line number
indications, display line number indications, and character number
indications generating as a television compatible composite video
output signal the indicated scan line of the output data character
of said coded output data character signal; and
h. first control means for causing said clock means to generate
clock pulses at a second frequency less than said first frequency
and for causing said first and second counting means to change the
scan line number and display line number less frequently, whereby
the visible display is of increased size.
2. Apparatus as claimed in claim 1 further comprising television
receiver means coupled to said video signal generator means and
responsive to said television compatible composite video output
signal for providing a visible display of at least some of said
first plurality of data characters.
3. Apparatus as claimed in claim 1 in which said decoding means
comprises a read-only memory.
4. Apparatus as claimed in claim 1 further comprising second
control means for causing said video signal generator means to
respond to said fourth plurality of data bits during only
substantially one-half of the cycles of said multiplexer means on
preselected ones of said data line number indications.
5. Apparatus as claimed in claim 4 in which the multiplexer means
cycles 60 times per second.
Description
The present invention pertains to data display. More particularly
the present invention pertains to the raster display of static
data.
In numerous situations, substantially static data is obtained, and
it is desired to display this data. By way of example, it is
frequently desired to display the contents of various registers
within a large-scale digital computer system during system
check-out or trouble shooting. Likewise, in other applications
two-state data is frequently available which it is desirable to
display. Thus, for example, a security system at a remote facility
might be instrumented to provide a two-state, safe-unsafe
indication. Frequently it is desired to display such data
simultaneously at a large number of locations, for example to
different layers of supervisory personnel. Some of the desired
display locations might be remote from the data sources, either due
to the nature of the organization or due to such considerations as
security.
Presently available data display systems are capable of the
instantaneous display of data available in two-state or binary
coded decimal form. Such presently available data display systems
have numerous shortcomings, however. Display tubes, such as
so-called NIXIE tubes, generally are capable of displaying only one
character at any one time, and so if a large number of characters
are to be displayed, an equally large number of display tubes is
required. The relatively high cost of such display tubes prohibits
the display of large quantities of data. Even with that data which
is displayed, the display is limited because any one display tube
is capable of displaying only a limited number of characters. Thus,
most display tubes are capable only of displaying either the 10
numerals or 10 preselected letters. This limit the variety of data
which can be displayed by any one display tube. Generally,
available display tubes offer only a standard selection of
available characters. Consequently, if the display of an unusual
character is desired, either it is not possible with presently
existing display tubes, or a special display tube must be
constructed for the purpose.
With presently existing data display devices, a separate connection
is required to the data source for each data character to be
displayed. Consequently, the display of a large number of
characters requires an equally large number of connections. As a
consequence, it is virtually impossible to place the display at a
location remote from the data source. Even if one display is
remotely located, the wiring required makes it impossible to
provide plural displays in different locations.
In addition, presently available display devices, when in
operation, are always displaying a digit. Therefore, leading zeros
cannot be eliminated. This results in some difficulty and confusion
in reading multidigit numbers having several leading zeros.
Furthermore, these presently available display devices are unable
to provide special features such as blinking of characters which if
done might attract attention to data indicating unusual conditions.
Likewise, the displays provided by presently available devices are
fixed, not only in color but also in intensity and in character
size.
While display devices have recently been developed in which the
electrical signals representing the data are fed to multipin
cathode ray tubes (CRT) which then display the data, such devices
have not overcome many of the shortcomings of data display tubes.
Thus, for example, such CRT display devices are limited in the
variety and in the quantity of characters they can display.
The present invention is a data display system overcoming these
several problems. The data display system of the present invention
is capable of simultaneously displaying a large number of data
characters in a plurality of remotely located, separated areas, and
is capable of displaying a large variety of characters.
Consequently, the cost per character is low. Only a single coaxial
connection is required between the character generating portion and
the output display device of this data display system. Therefore,
the output display device can be situated at a location quite
remote from the data sources, and, if desired, numerous output
display devices can be utilized simultaneously, each in a different
location. If desired, the data display characters can be
transmitted as television signals and received by commercial
television receivers at a plurality of remote locations. The data
display system of the present invention can additionally provide on
a display line by display line basis such features as blinking of
characters to attract attention to significant data, alternation of
color to provide either white characters on a black background or
black characters on white background, variation in intensity of the
white background or characters, and variation in character size to
provide a more prominent display of significant data.
In the data display system of the present invention, a plurality of
data characters are fed to a serializer which receivers
character-identifying instructions from an address generator and in
response thereto transmits one data character at a time to a
read-only memory (ROM). The ROM provides 20 eight-bit scan line
signals for each data character. These eight-bit scan line signals
are sent to a character generator which converts them into the
necessary signals for application via a single coaxial cable to one
or more television receivers or other output display devices which
may be separately remotely located. The character size can be
varied. The display might be either white-on-black or
black-on-white, and in either case, the intensity of the white can
be varied. Data can be made to blink so as to attract attention to
data indicating unusual conditions, and leading zeros can be
blanked out.
These and other aspects and advantages of the present invention are
apparent from the following detailed description and claims,
particularly when read in conjunction with the accompanying
drawings in which like parts bear like reference numerals. In the
drawings:
FIG. 1 is a block diagram of the data display system of the present
invention;
FIG. 2 depicts typical output display characters which can be
provided by the data display system of the present invention;
and
FIG. 3 illustrates the output display provided by the system of the
present invention.
The data display system of FIG. 1 is capable of displaying up to
160 data characters simultaneously on a data display device such as
a commercially available television receiver. These 160 data
characters are presented in 10 display lines of 16 characters each.
Each display line includes 20 horizontal scan lines.
Clock 20, which by way of example might include a crystal
controlled oscillator and the necessary dividing circuits, provides
a pulse output on line 22 at for example 400 kilohertz (KHz). This
400-KHz output is applied to character counter 24, display line
counter 26 and scan line counter 28. Character counter 24 keeps
count of which of the 16 character positions on a given display
line a character is to be displayed at, while display line counter
26 keeps track of which of the 10 display lines that character is
to be displayed at, and scan line counter counts the 20 scan lines
of each display line.
The character number and display line number signals are applied by
their respective counters to multiplexer 30. These signals might be
binary coded signals, and if so would each require four lines for
transmission.
In the data display system depicted in FIG. 1, multiplexer 30
receives a plurality of binary coded decimal (BCD) data signals
representing the data characters which are to be displayed. Thus,
for example, multiplexer 30 might receive 160 BCD input data
characters, each on a group of four input lines giving a total of
640 input data lines. In FIG. 1, the input line groups for this
example of 160 data characters are designated 0,1,2 . . . 159 to
correspond to the designations of the 160 input data characters.
Utilizing the character number and display line number signals
received from counters 24 and 26, multiplexer 30 selects the proper
input data character for application to read-only memory ROM 32. In
the data display system of FIG. 1, in which each of the 160 data
characters is received via four input data lines, multiplexer 30
might include, by way of example, four identical AND gate matrices,
each having 16 columns and 10 rows of AND gates. Each AND gate in a
particular matrix receives one input data line, one character
number input, and one display line number input. As character
counter 24 and display line counter 26 operate, one gate in each of
the four matrices is enabled, and so the corresponding BCD input
data character is applied by multiplexer 30 to ROM 32 via the four
lines 34.
FIG. 2A depicts the output display of the data character 0. As can
be seen, the illustrative data character, and every such
illustrative data character, is made up of 13 eight-bit scan lines.
If it be considered that a binary one is presented when a bit
position is energized and that a binary zero is presented when a
bit position is not energized, then during display of the data
character 0, as depicted in FIG. 2A, the eight-bit positions of
scan line 0 are 0,0,1,1,1,1,0,0. Likewise, the bit positions of
scan line 1 are 0,1,0,0,0,0,1,0, while the bit positions of scan
lines 2-10 are 1,0,0,0,0,0,0,1. The bit positions of scan line 11
are 0,1,0,0,0,0,1,0, and those of scan line 12 are 0,0,1,1,1,1,0,0.
As has been stated, 20 scan lines make up each display line. Scan
lines 13-19 are blank to provide the necessary vertical spacing
between adjacent lines of data. Thus, all the bit positions for
scan lines 13-19 are 0. FIG. 2 depicts in a similar manner the
output displays for several other typical data characters.
ROM 32 receives the scan line number from scan line counter 28 and
the input data character from multiplexer 30, and in response to
these, ROM 32 transmits via the eight connections 36 to video
signal generator 38, the eight bits forming that scan line for the
designated data character. Thus, if the desired data character is a
0, during scan line 0 ROM 32 transmits via the eight connections 36
to video signal generator 38 the eight bits 0,0,1,1,1,1,0,0. ROM 32
might be any suitable read only memory capable of translating the
20 scan lines of the 160 data characters into the necessary eight
binary bits. Thus, for example, ROM 32 might be a woven braid
magnetic core memory, or it might be an integrated circuit memory
device such as a four phase MTOS, 2048-bit read-only memory
manufactured by Microelectronics Division, General Instrument
Corp., Hicksville, New York.
Video signal generator 38 receives the eight data bits via line 36
and receives the character number, display line number, and scan
line number from counters 24, 26 and 28. The character number is
applied to a horizontal synchronization generator, while the
character number, display line number and the scan line number are
applied to a vertical synchronization generator. The eight data
bits which are received in parallel from ROM 32 pass through a
parallel-to-serial converter from which they are applied one bit at
a time to a two-state signal generator, the output of which is
applied with the outputs of the two synchronization generators to
appropriate mixing circuitry to provide the desired composite video
output signal which contains vertical synchronization information,
horizontal synchronization information, and the two-state signal
information. This composite video output signal is applied by cable
40 to output display device 42 which by way of example might be any
commercially available television receiver. Cable 40 is preferably
a coaxial cable with an impedance of 75 ohms.
FIG. 3 illustrates the output display provided by means of the data
display system of the present invention and utilizing as an output
display device a commercial television receiver. The system
operates with such a receiver in a non-interlaced mode and so there
are 240 scan lines available. To insure against loss of data
characters on the output display, the 20 uppermost and the 20
lowermost scan lines are left blank, and so 200 usable scan lines
are available. In the illustrative example of FIG. 3, each scan
line is made up of 160 points or data bits. Each of the 16 data
characters which might be provided on a display line thus has 10
points or data bits. Since each character provided by the system
utilizes only eight bits, the remaining two bits provide the
necessary horizontal spacing between characters. Of course, any
convenient number of points could be provided in each scan line in
accordance with the present invention. It is desirable that about
20 percent of the points available per character be utilized for
the horizontal intercharacter spacing.
FIG. 3 illustrates the various sizes in which data might be
displayed. Thus, in display line 0, the uppermost display line, the
data display "A927" is presented, which might represent any
received data. Since only four data characters are presented, the
remaining 12 characters of display line 0 are not energized and
thus remain blank. This is possible by having ROM provide all
binary zeros for those data characters in response to an indication
from multiplexer 30 that a blank is intended, as distinguished from
a leading zero.
Displays such as that illustrated in FIG. 3 are generated scan line
by scan line. Thus, display line 0 is generated one scan line at a
time with binary zeros for all the data bits for the first 12 data
characters, followed by the appropriate pattern of data bits to
form scan line 0 of the data character A as depicted in FIG. 2F.
This is followed by the appropriate patterns of data bits to form
scan line 0 of the data characters 9, 2, and 7, as shown in FIG.
2E, 2C, and 2D, respectively. The system then flies back to the
first bit of scan line 1 of data character 0. This scan line is
then displayed. Each data bit for the first 12 characters is a
binary zero, and then the patterns for scan line 1 of the
characters A, 9, 2, and 7 are presented, as depicted in FIG. 2.
Each succeeding scan line is likewise presented. The application of
each data bit is triggered by pulses from clock 20. The output of
clock 20 is applied to video signal generator 38 to pump the data
bits through that device. Character counter 24 counts the clock
pulses and changes the character number every 10 pulses (eight data
bits and two space bits). Scan line counter 28 likewise counts the
clock pulses and changes the scan line number every 160 pulses.
Likewise, display line counter 26 counts the clock pulses and
changes the display line number every 3,200 pulses. As previously
described, the character number and the display line number are
applied to multiplexer 30 to gate the proper input data character
to ROM 32, while the scan line number is applied to ROM 32 to cause
passage therefrom of the proper data bit pattern for the particular
data character received by ROM 32 from multiplexer 30. The
character number, the display line number and the scan line number
are applied to video signal generator 38 to cause generation of the
appropriate vertical and horizontal synchronization signals.
Preferably the appropriate gates within the four matrices in
multiplexer 30 are enabled, as previously described, and then the
data character is passed through these gates by the application of
a pulse delayed in time from the clock pulses to insure that each
gate has stabilized prior to activation. For this purpose the clock
pulses are applied in multiplexer 30 to an appropriate delay device
such as a delay multivibrator. A similar technique can be utilized
within video signal generator 38, if desired, to insure generation
of the appropriate binary data bit.
Output display device 42 is capable of displaying 160 data
characters in 10 display lines of 16 data characters each. To give
emphasis to particular data, several variations in the display are
possible on a display line by display line basis. By way of
examples, the character size can be doubled or quadrupled, a
display line can be caused to blink to draw attention to it, a
display line can be displayed as black characters on a white
background rather than white characters on a black background, and
the intensity of the white, either characters or background, can be
changed. To accomplish these, a set of five control lines is
provided to multiplexer 30 for each of the possible 10 display
lines. FIG. 1 depicts one set of these control lines: one color
control line to enable selection of white on black or black on
white displays, one intensity control line to enable variation of
the white intensity, one blink control line to enabling the
blinking of a data line, a size 2 control line to enable the
doubling of the size of the characters, and a size 4 control line
to enable the quadrupling of the size of the characters. Similar
sets of these five control lines are provided for each display
line.
As display line counter 26 enables each of the AND gates within
multiplexer 30 associated with a particular display line, it also
enables AND gates associated with the five control lines for that
display line. If a control signal is present on one or more of
these control lines, the control signal is passed to the output
control lines from multiplexer 30. If neither a size 2 nor a size 4
signal is present, then size 1 characters are generated. If both a
size 2 and a size 4 signal are present, the size 4 signal overrides
the size 2 signal, and a size 4 output control signal is provided
from multiplexer 30.
As multiplexer 30 commences the passage of a display line, the five
control line inputs are monitored, and if a control signal is
present on any one of them, a switching circuit such as a flip-flop
is set and remains set for the remainder of that display line to
provide the output control signals from multiplexer 30.
The output display device might display 10 display lines of
characters of size 1 as depicted in display line 0 of FIG. 3. Each
line of that size might contain up to 16 characters. If some data
is of greater significance than other data, then that more
significant data might be displayed in larger characters. To double
each dimension of the data characters of a given display line, the
size 2 input control line to multiplexer 30 is energized. As a
result, a size 2 control signal is applied from multiplexer 30 to
clock 20, character counter 24, display line counter 26, and scan
line counter 28. In response to this signal, character counter 24
is preset to 8 so that only the characters number 8 through number
15 of any display line are displayed. The frequency of clock 20 is
cut in half so that each binary bit from video signal generator 38
lasts twice as long and thus has twice as great a horizontal
deflection on the display screen of output display device 42. Scan
line counter 28 counts every other clock pulse so that each scan
line is repeated twice, thereby resulting in each line having twice
the vertical deflection on the display screen of output display
device 42. Alternatively, scan line counter 28 counts twice as many
pulses before changing the scan line number. Display line counter
26 likewise counts every other clock pulse, and after counting
3,200 pulses adds two to the display line number. Alternatively,
display line counter 26 counts 6,400 pulses before changing its
display line number and then adds two to that number. As a result,
as depicted by the display at display lines 1 and 2 in FIG. 3, the
output display is doubled in horizontal size and in vertical size,
and the vertical interline spacing is doubled.
In like manner, to give an output display four times as large, both
horizontally and vertically, as that in display line 0 of FIG. 3, a
signal is applied on the size 4 input control line to multiplexer
30. As a result, a size 4 control signal is applied from
multiplexer 30 to clock 20, character counter 24, display line
counter 26, and scan line counter 28. In response to this signal,
character counter 24 is preset to 12 so that only the characters
number 12 through number 15 of any display line are displayed. The
frequency of clock 20 is cut to one-fourth its original value so
that each binary bit from video signal generator 38 lasts four
times as long as originally and thus has four times as great a
horizontal deflection as originally on the display screen of output
display device 42. Scan line counter 28 either counts every fourth
clock pulse or counts four times as many pulses before changing its
scan line number. As a result, each scan line is repeated four
times. Likewise, display line counter 26 either counts every fourth
pulse or counts four times as many pulses, and then adds four to
the display line number. Consequently, as depicted by the display
at display lines 3 - 6 in FIG. 3, the output display is four times
as great in horizontal size and in vertical size, and the vertical
interline spacing beneath that line of data is four times as
great.
Output display device 42 can display 10 lines of size 1 characters,
or 10 character lines. Each size 2 character takes two character
lines, and each size 4 character takes four character lines. Thus,
the number of lines of data actually displayed on device 42 is
determined by the size of the display lines, and any combination of
display lines sizes totaling not more than 10 character lines might
be displayed.
In like manner, if a color control signal, or intensity control
signal or a blink control signal is applied to multiplexer 30 for a
particular display line, when that display line is passed to ROM 32
the one or more control signals are passed to video signal
generator 38. A color control signal sets a flip-flop within
generator 38 to reverse the video output display for that display
line so that black characters are shown on a white background. An
intensity control signal reduces the intensity of the white display
by reducing the signal applied for the white, whether the white be
background or character. A blink control command causes the video
signal generator for example to repeatedly skip eight frames and
then transmit eight frames for that display line to cause the
display line to blink on output display device 42.
Clock 20 has a basic frequency of 400 KHz. Multiplexer 30 is
scanned 60 times per second to provide a 60 frame per second output
from video signal generator 38 which is compatible with
commercially available television receivers. The remaining time is
required for flyback and other control functions.
Since only a single coaxial cable 40 is required to connect output
display device 42 to the remainder of the apparatus, the output
display device might be located at a considerable distance from the
remainder of the equipment. Several output display devices, each in
a different location, might be connected at the same time to video
signal generator 38 by separate coaxial cables to provide output
displays in a number of separated, remote locations. If desired,
the output of video signal generator 38 could be applied to
appropriate transmitter equipment and transmitted a considerable
distance to one or more receivers having suitable antennae, thereby
eliminating the necessity of connecting the receivers directly to
generator 38. The input data sources might also be remotely and
separately located and connected to multiplexer 30 by appropriate
wiring.
The number of different data characters which can be provided is
determined by ROM 32. The input data might be in BCD format or
hexadecimal code format or any other suitable code. ROM 32 is
designed to translate the received data format to the appropriate
scan line bits. If a new character is desired, it is only necessary
to provide the proper decoding-translating circuitry in ROM 32.
Thus, numbers, letters, and other desired symbols might be
provided.
Multiplexer 30 has been described with reference to AND gate
matrices. Other suitable multiplexing apparatus might be utilized.
Thus, by way of examples, a plurality of electromechanical stepping
switches, a series of shift registers, or any other
parallel-to-serial converter apparatus might be utilized.
* * * * *