Note: Descriptions are shown in the official language in which they were submitted.
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VARIABLE COLOR COMPARISON OSCILLOSCOPE
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to measuring devices utilizing a
variable color display.
2. Description of the Prior Art
A digital oscilloscope disclosed in U. S. Pat. No.
3,816,815, issued on June 11, 1974 to Robert W. Schumann,
includes an A/D converter for converting a measured waveform
to binary data which are stored in a memory and which may be
utilized to reconstruct the waveform for displaying it on a
monochromatic display.
A solid state oscilloscope disclosed in U. S. Pat. No.
4,114, 095, issued on Sep. 12, 1978 to Jacques Isaac Pankove
et al., includes an array of monochromatic l~ght emitting
diodes arranged in rows and columns. The columns of the
array are continuously scanned, and measured voltage is
applied to the rows to display the test waveform.
A variable color comparison oscilloscope is unknown.
.?~q~?
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SUMMARY OF THE INVENTION
The present invention endeavors to provide a measuring
instrument capable of displaying the relationship between
the amplitude of a measured signal and time.
It is another object of the invention to provide a
waveform measuring instrument capable of simultaneously
displaying the measured waveform and its relation to
predetermined limits.
It is still another object of the invention to provide a
variable color comparison oscilloscope.
It is further object of the invention to provide a
variable color comparison memory oscilloscope.
In summary, a comparison oscilloscope of the invention
includes a waveform measuring device and a variable color
display for exhibiting the measured waveform. Color control
is provided for illuminating in a first color the portions
of the exhibited waveform that are within predetermined
limits and in a second color the portions of the exhibited
waveform that are outside the limits.
Further objects of the invention wi:Ll become obvious from
the accompanying drawings and their description.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings in which are shown the preferred
embodiments of the invention,
FIGS. la to lc are examples of a variable color bar graph
display on which instant measured values and their relations
to a previous measured value are simultaneously exhibited.
FIG. 2 is a block diagram of a variable color analog
display voltmeter capable of indicating the relation of
instant measured value to previous measured values.
FIG. 3 is a simplified schematic diagram of a variable
color bar graph voltmeter capable of indicating the relation
of instant measured value to a previous measured value.
FIG. 4 is a cross-sectional view, taken along the line
4-4 in FIG. lc, revealing internal structure of a portion of
a variable color bar graph display device.
FIG. 5 is a schematic diagram of a timing generator.
FIG. 6a is a plan view of a prior art monochromatic
display on which an exemplary pattern in the form of a
square is displayed.
FIG. 6b is a plan view of a prior art monochromatic
display on which an exemplary pattern in the form o~ a cross
is displayed.
FIG. 7 is a plan view of a variable color display on
which both previous patterns are simultaneously displayed in
different colors.
FIG. 8 is a cross-sectional view, taken along the line
8-8 in FIG. 7, revealing internal structure of one row of a
variable color display.
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FIG. 9 is a block diagram of a matrix oE variable color
display areas arranged in rows and columns.
FIG. 10 is a cross-sectional view, similar to the view
shown in FIG. 8, revealing internal structure of one row of
a variable color display with memory.
FIG. 11 is a schematic diagram showing the detail of one
display element of FIG. 8.
FIG. 12 is a schematic diagram showing the detail of one
display element of FIG. 10.
FIG. 13a is a timing diagram showing the relationship of
signals for illuminating red LED in the selected display
element.
FIG. 13b is a timing diagram showing the relationship of
signals for illuminating green LED in the selected display
element.
FIG. 14a is a detail showing measurement limits for an
exemplary waveform.
FIG. 14b is a detail showing the relationship of an
exemplary measured waveform to the measurement limits shown
in FIG. 14a.
FIG. 15 is a simplified schematic diagram oE a variable
color comparison oscilloscope.
FIG. 16 i.s a simplified schematic diagrarn of a variable
color comparison memory oscilloscope.
FIG. 17 is a timing diagram of the variable color
comparison memory oscilloscope of FIG. 16.
Throughout the drawings, like characters indicate like
parts.
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DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now, more particularly, to the drawings, FIGS.
la to lc are examples of a variable color bar graph display
on which are shown three examples of instant measured values
and their relations to a previous measured value.
Considering the full scale to be 10 Volts, each display
element in bar graph display 11 represents 1 Volt step.
Thus display element la represents 1 Volt, display element
lb represents 2 Volts, display element lc represents 3
Volts, etc. It would be obvious that the illustrated display
may represent other scales of other 4uantities.
By referring to several illustrated examples, FIG. la
simultaneously exhibits instant measured value 5 Volts by
illuminating display elements la, lb, lc, ld, and le in
yellow color. The remaining display elements lf, lg, lh, li,
and lj are extinguished. Yellow color of all illuminated
display elements la to le indicates that the instant
measured value is unchanged Erom the previously measured
value.
FIG. lb exhibits instant measured value 8 Volts by
illuminating display elements la, lb, lc, ld, and le in
yellow color and display elements lf, Ig, and lh in red
color. Yellow color of display elements la to le indicates
that previously measured value was 5 Volts. Red color of
display elements lf to lh indicates the increase in the
measured value by 3 Volts.
FIG. lc exhibits instant measured value 3 Volts by
illuminating display elements la, lb, and lc in yellow color
and display elements ld and le in green color. Yellow color
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of display elements la to lc indicates that instant measured
value is 3 Volts. Green color of display elements ld and le
indicates the decrease in the measured value by 2 Volts. The
previous measured value was 5 Volts (all display elements la
to le).
In FIG. 2 is shown a block diagram of a variable color
analog voltmeter of the invention which includes an analog
comparator 14, for comparing input signal Vin with reference
values, and a display driver 15, for causing an analog
i 10 indication of the value of the input signal to be exhibited
on a variable color analog display 10, in a manner well
understood by those skilled in the art. The invention
resides in the addition of a memory 21, for storing from
time to time measured values for later use, as determined by
a timing generator 22, and color control 20, for controlling
the color of the exhibited analog indication of the instant
measured value in accordance with its relation to previous
measured values. The analog voltmeter of the invention is
thus capable of simultaneously exhibiting an instant
measured value, by analog indication, and its relation to
previous measured values, by color.
Proceeding now to the detailed description, in FIG. 3 is
shown a simplified schematic diagram of a variable color bar
graph voltmeter of the invention. The circuit employs a
commercially available bar display driver 16a which contains
a string of voltage comparators combined with a voltage
reference network for detecting the level of an input signal
Vin, applied to its input SIG IN, and for accordingly
developing output drive signals to illuminate certain of
display elements la to lj for providing a linear analog
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indication of the level of the input signal. The voltmeter
operates in a bar mode, which is achieved by tying its MODE
input to a high logic level. The value of resistor 9n
coupled to reference output pin REF OUT determines the LED
current and therefore the brightness of bar graph display
11. As will become more clear from the following
description, the relation between the values of resistor 9n
and resistors 9a to 9j determines the composite color of bar
graph display 11.
Each display element la to lj of bar graph display 11
includes a pair of closely adjacent LEDs (light emitting
diodes): a red LED 2 and green LED 3 which are adapted for
producing a composite light signal of a variable color. The
cathodes of all red LEDs 2a, 2b, 2c, 2d, 2e, 2f, 2g, 2h, 2i,
and 2j are respectively coupled to the outputs LED 1, LED 2,
LED 3, LED 4, LED 5, LED 6, LED 7, LED 8, LED 9, and LED 10
of bar display driver 16a. The cathodes of all green LEDs
3a, 3b, 3c, 3d, 3e, 3f, 3g, 3h, 3i, and 3j are respectively
coupled, via current limiting resi.stors 9a, 9b, 9c, 9d, 9e,
9f, 9g, and 9h, to the outputs Q0, Ql, Q2, Q3, Q4, Q5, Q6,
and Q7 of an octal flip-flop 19a and, via current limiting
resistors 9i and 9j, to the outputs Q0 and Ql of a dual
flip-flop 19b. The flip-flops l9a and l9b have their Output
Enable inputs OE grounded for enabling the outp~ts Q0 to Q7.
The anodes of all red LEDs 2a to 2j and all green LEDs 3a to
3j are commonly coupled to a power source +VCC. The data
inputs D0 to D7 of octal flip-flop l9a and data inputs DO
and Dl of dual flip-flop l9b are respectively coupled, via
non-inverting buffers 8a to 8j, for assuring correct logic
levels, to outputs LED 1 to LED 10 of bar display driver
3S~7
16a.
The operation of the analog voltmeter will be explained
by three examples. EXAMPLE la considers previous measured
value 5 Volts and instant measured value also 5 Volts. When
previous measured value was 5 Volts, outputs LED 1, LED 2,
LED 3, LED 4, and LED 5 of bar display driver 16a were at a
low voltage level, thereby causing display elements la, lb,
lc, ld, and le to illuminate in red color, and the remaining
outputs LED 6 to LED 10 were at a high voltage level,
thereby causing display elements lf, lg, lh, li, and lj to
extinguish. Low voltage levels a~ the outputs LED 1, LED 2,
LED 3, LED 4, and LED 5 are respectively applied, via
buffers 8a, 8b, 8c, 8d, and 8e, to inputs D0, Dl, D2, D3,
and D4 of octal flip-flop 19a. When a leading edge of pulse
29 occurs, indicating the end of the previous measuring
interval, the data at the inputs D0 to D7 are clocked into
octal flip-flop 19a, into dual flip-flop 19b, and appear at
respective outputs Q0 to Q7. As a result, the outputs Q0 to
Q4 of octal flip-flop 19a drop to a low logic level, and the
remaining outputs Q5 to Q7 of octal flip-flop 19a and
outputs Q0 and Ql of dual flip-flop 19b rise to a high logic
level. The current flows from the source ~VCC, via green
LED 3a and resistor 9a to output Q0, via green LED 3b and
resistor 9b to output Ql, via green LED 3c and resistor 9c
to output Q2, via green LED 3d and resistor 9d to output Q3,
and via green LED 3e and resistor 9e to output Q4. As a
consequence, green LEDs 3a, 3b, 3c, 3d, and 3e illuminate
and remain illuminated until different data are clocked into
flip-flops 19a and 19b. The remaining green LEDs 3f to 3j
are extinguished, because the remaining outputs Q5 to Q7 of
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octal flip-flop 19a and outputs Q0 and Ql of dual flip-flop
l9b are at a high logic level.
Considering the new measured value to be again 5 Volts,
the outputs LED 1 to LED 5 of bar display driver 16a drop to
a low voltage level, and the remaining outputs LED 6 to LED
10 rise to a high voltage level. As a consequence, red LEDs
2a, 2b, 2c, 2d, and 2e illuminate. As a result of internal
blending, display elements la to le illuminate in
substantially yellow color. The absence of red and green
colors in bar graph display 11 indicates that the instant
measured value is unchanged from the previously measured
value, as viewed in FIG. la.
EXAMPLE lb considers previous measured value 5 Volts and
instant measured value 8 Volts. When the new measured value
is 8 Volts, the outputs LED 1 to LED 8 of bar display
driver 16a drop to a low voltage level, and the remaining
outputs LED 9 and LED 10 rise to a high voltage level. As a
consequence, red LEDs 2a, 2b, 2c, 2d, 2e, 2f, 2g, and 2h
illuminate. As a result of internal blending, display
elements la to le illuminate in substantially yellow color.
The display elements lf to lh illuminate in red color. The
presence of red color in bar graph display 11 indicates that
the instant measured value is increased from the previously
measured value, as viewed in FIG. lb.
EXAMPLE lc considers previous measured value 5 Volts and
instant measured value 3 Volts. When the new measured value
is 3 Volts, the outputs LED 1 to LED 3 of bar display
driver 16a drop to a low voltage level, and the remaining
outputs LED 4 to LED 10 rise to a high voltage level. As a
consequence, red LEDs 2a, 2b, and 2c illuminate. As a result
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of internal blending, display elements la to lc illuminate
in substantially ye]low color. The display elements ld and
le remain illuminated in green color. The presence of green
color in bar graph display 11 indicates that the instant
measured value is decreased from the previously measured
value, as viewed in FIG. lc.
An important consideration has been given to physical
arrangement of the light emitting diodes in display elements
la to lj, as illustrated in FIG. 4. In display element lj,
red LED 2j and green LED 3j are disposed on a support 4 in a
light blending cavity 5j and are completely surrounded by a
transparent light scattering material 6. When forwardly
biased, LEDs 2j and 3j emit light signals of red and green
colors, respectively, which are blended by passing through
light scattering material 6, acting to disperse the light
signals, to form a composite light signal that emerges at
the upper surface of display element lj. The color of the
composite light signal may be controlled by varying the
portions of red and green light signals. In display element
li, red LED 2i and green LED 3i are similarly disposed in a
light blending cavity 5i and may 'be similarly activated.
The display elements lj and li are optically separated
from one another 'by opaque wall 7'b. Although not shown, it
will be appreciated that the remaining display elements are
similarly optically separated. In display element lj,
opaque walls 7a and 7b have generally smooth inclined
surfaces 13a and 13'b defining an obtuse angle with support 4
and defining a light blending cavity 5j therebetween. In
display element li, inclined surfaces 13c and 13d of opaque
walls 7b and 7c similarly define a light blending cavity 5i
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therebetween. Although opaque walls 7 and light blending
cavities 5 are shown to be of certain shapes and dimensions,
it is envisioned that they may be modified and rearranged.
FIG. 5 is a schematic diagram of timing generator 22 of
FIG. 2 which includes a timer 25 operating in its astable
mode for producing at its output OUT a train of pulses 29a
of a relatively high frequency determined by the values of
resistors 9s, 9t and capacitors 27a, 27b. The pulses 29a are
applied to CLOCK input of a 14-bit counter 26 to divide
their frequency by 16,384 and to provide at its output Q14
pulses 29 of a relatively low frequency. When considering an
exemplary frequency of pulses 29a to be 1.6384 kHz, the
frequency of pulses 29 will be 0.1 Hz.
In FIG. 6a is shown an exemplary display pattern in the
shape of a square displayed in green color on a commercially
well known 5x7 dot matrix monochromatic display 30a.
Another display pattern in the shape of a cross is displayed
in red color on a like monochromatic display 30b shown in
FIG. 6b.
As illustrated in FIG. 7, both previous display patterns
may be simultaneously displayed on a single variable color
display 31 similarly arranged in a 5x7 dot 0atrix. To
facilitate the comparison, the two patterns are displayed
according to the following system. The display areas that
are illuminated only on display 30a, such as area 41i, are
illuminated on display 31 in green color. The display areas
that are illuminated only on display 30b, such as area 41j,
are illuminated on display 31 in red color. The display
areas that are illuminated on both displays 30a, 30b and
that would therefore overlap, such as area 41k, are
illuminated on display 31 in yellow color. The display
areas that are extinguished on both displays 30a and 30b,
such as area 41n, are also extinguished on display 31. It
would be obvious that other color combinations may be
devised.
An important consideration has been given to physical
arrangement of the LEDs in the display areas, as illustrated
in FIG. 8. The pairs of LEDs 2a and 3a, adapted for emitting
light of red and green coLors, respectively, are disposed in
respective chambers 33 which are optically separated from
one another by opaque walls 35. Although the chambers are
shown to be of certain shapes and dimensions, it is
envisioned that they may be modified and rearranged. In the
exemplary chamber 33a, defined by walls 35a and 35b, LEDs 2a
and 3a are mounted on a suitable support 32 and completely
surrounded by light scattering material 6. When only one
LED 2a or 3a is energized, by means of a circuit shown in
,i FIG. 11, it emits light of either primary color through
aperture 3~ formed in top wall 35c. When both LEDs 2a and
3a are energized, light signals of red and green primary
colors are blended, by passing through light scattering
material 6, to form a composite light signal of
substantially yellow color that emerges from aperture 34.
The matrix of variable color display areas arranged in
rows and columns illustrated in FCG. 9 corresponds to
variable color display 31 viewed in FIG. 7. A particular
display area may be conveniently identified by its row and
column numbers. By way of an example, display area 41b is
located at row 1 and column 2. The display area 41f is
located at row 7 and column 5. To facilitate the
12
~6~5~7
addressing, each display area has a Row input R, Column
input C, Red Data input RD, and Green Data input GD, all
adapted for accepting logic level signals. It is clearly
evident from FIG. 9 that the Row inputs R of all disp]ay
areas located in the same row are coupled. Similarly, the
Column inputs C of all display areas located in the same
column are coupled. The Red Data inputs RD of all display
areas in the matrix are coupled. In a similar fashion, the
Green Data inputs GD of all display areas are coupled. All
display areas 41a to 41f may be extinguished by applîcation
of a suitable reset pulse, as will be revealed subsequently.
To illuminate a desired portion in a desired display area,
it is necessary to simultaneously activate the row input in
which the area is located, the column input in which the
area is located, and either of, or both, inputs RD, GD.
The variable color display illustrated in FIG. 10
includes five display elements disposed in chambers
separated by respective walls 45. The exemplary display
element located in chamber 43a, deEined by walls 45a and
45b, includes two pairs of associated closely adjacent
light emitting diodes and phototransistors 2a and 48a, 3a
and 48b electrically coupled as in FIG. 12. The light
emitting diodes 2a and 3a are adapted for emitting upon
activation Light signals of red and green colors,
respectively. In a small chamber 47a, phototransistor 48a is
completely surrounded by chamber walls 45a, 45c, and 46a,
but its associated light emitting diode 2a is only partially
disposed therein, being partially overlayed by opaque
chamber wall 46a such that its one portion is located within
small chamber 47a, and its remaining portion is located
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within chamber 43a. The vertically extending portion of
chamber wall 46a abuts light emitting diode 2a and provides
a hermetic seal therebetween so as to secure small chamber
47a from the presence of ambient light. The active area of
phototransistor 48a is oriented to intercept light signals
emitted from the portion of light emitting diode 2a within
chamber 47a to exert a toggle effect by varying the
resistance of phototransistor 48a in a sense tending to
stabilize light emitting diode 2a either in its illuminated
condition or in its extinguished condition. The
phototransistor 48b is similarly completely disposed in
small chamber 47b, and its associated light emitting diode
3a is partially disposed therein and partially disposed in
chamber 43a, being divided by vertically extending wall 46b.
The light signals emitted from the portions of light
emitting diodes 2a and 3a that are located in chamber 43a
are blended by passing through transparent light scattering
material 6 to form a composite light signal. An aperture
34a is formed in top wall 45c such that the composite light
signal may be viewed externally.
In FIG. 11 is shown a schematic diagram of one display
element of FIG. 8 which includes red LED 2a, green LED 3a,
and resistors 49a, 49b accommodated in a chamber defined by
side walls 35a, 3Sb and top wall 35c. When a positive
voltage of suitable value is applied to the input A, current
flows via current limiting resistor 49a, which confines the
current flow, and LED 2a to ground, causing red LED 2a to
illuminate and to maintain its illuminated condition as long
as the voltage is present at the input A. In a similar
fashion, a suitable positive voltage applied to the input B
14
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causes green LED 3a to illuminate. As was indicated earlier,
light signals emitted by LEDs 2a and 3a are blended to form
a composite light signal of substantially yellow color.
The display element shown in FIG. 12 additionally
includes AND gates 42a and 42b, for gating signals R, C, RD,
GD, and is capable of retaining the conditions of LEDs 2a
and 3a after termination of the input signals. To reset the
display element, a low logic level is momentarily applied to
its Clear input CLR. As a consequence, the output of a
preferably TTL (Transistor Transistor Logic) buffer 39 also
drops to a low logic level. Since a TTL device is not
capable of sourcing current from a low logic level output,
no current can flow therefrom to ground. The LEDs 2a and 3a
in all display elements therefore extinguish, and the
resistances of phototransistors 48a and 48b in all elements
rise to very high values. When a high logic level returns
to the input CLR, the output of buffer 39 also rises to a
high logic level. However, the currents flowing via resistor
49e, high resistance of phototransistor 48a and LED 2a to
ground, and in parallel, via resistor 49f, high resistance
of phototransistor 48b and LED 3a to ground, are very small
and not sufEicient to illuminate LEDs 2a and 3a. This state
is therefore stable and will exist until the inputs R, C,
RD, and GD are properly activated.
The operation of the display element in FIG. 12 will be
explained by examples of illuminating its either portion.
Assuming that the exemplary display element 41b is located
at the intersection of the row 1 and column 2 in FIG. 9 and
by referring additionally to FIG. 13a, to illuminate red LED
2a, a positive going pulse 50a is applied to the input ROW
~2~
1, to activate via bufEer 39a all Row inputs R in row 1,
positive going pulse 50b is applied to the input COL 2~ to
activate via buffer 39d all Column inputs C in column 2 ? and
positive going pulse 50c is applied to the input RD, to
activate via bufers 39f, 39m, etc., RD inputs of all
display elements. The width of pulse 50c depends on the
response time of the phototransistor and should be
sufficient to allow its resistance to drop below a
predetermined triggering point. As a consequence, the
output of AND gate 42a only in display element 41b rises
momentarily to a high logic level, and current flows
therefrom via resistor 49d and LED 2a to ground. The red
LED 2a illuminates, and its emission causes the resistance
of its associated phototransistor 48a to rapidly drop to a
very low value. As a result of a positive optical feedback,
whereby the increase in luminance of LED 2a causes the
decrease in resistance of phototransistor 48a which in turn
has an effect of further increase in the luminance and
urther decrease :in the resistance, the current in the red
LED branch, from bufer 39, via resistor 49e and
phototransistor ~8a7 sharply rises to a value suEicient to
maintain LED 2a fully illuminated. At the conclusion o
pulse 50c, the magnitude of the LED current is limited
substantially by the value of current limiting resistor 49e.
It is readily apparent that this state is stable and will
exist until another input of the display element is
activated.
Similarly, to illuminate green LED 3a in display element
41b, with reference to FIG. 13b, pulse 50a is applied to
the input ROW 1, pulse 50b is applied to the input COL 2,
16
~2~
and pulse 50d is applied -to the input GD. As a consequence,
the output of AND gate 42b only in display element 41b rises
momentarily to a high logic level, and current flows
therefrom via resistor 49c and LED 3a to ground, thereby
causing green LED 3a to illuminate and to be stabilized in
its illuminated condition by virtue of an optical feedback
to its associated phototransistor 48b, until it is reset.
When both red LED 2a and green LED 3a in the same display
area are illuminated, the light signals of red and green
colors are blended within the display area to form a
composite light signal of substantially yellow color, as
indicated previously.
When the output of buffer 39 is at a high logic level,
the specific voltage therein may be within a wide voltage
range. However, the voltage is the same for all LED
branches connected thereto. Thus the accuracy of the ratio
of currents in the LED branch pairs in each display element
and resulting accuracy of the hue of composite light depend
only on the matching of the current limiting resistors in
each pair.
Two display patterns, each including a plurality of
pattern elements corresponding to display areas of the
variable color display 3:l, may be simultaneously displayed
thereon. The display pattern in the forrn of a square shown
in FIG. 6a may be illuminated on variable color display 31
in green color by activating GD inputs of all display areas
located within the columns 2 to 4 and rows 3 to 5. The
display pattern in the form of a cross shown in FIG. 6b may
be illuminated on display 31 in red color by activating RD
inputs of all display areas in the column 3 and all display
~2613~;~7
areas in the row 4. It is readily apparent that all
overlapping display areas will illuminate in yellow color
due to blending of red and green colors therein. The two
illuminated patterns may be now readily compared, as viewed
in FIG. 7. The portions that appear only in the display
pattern shown in FIG. 6a are illuminated in FIG. 7 in green
color, the portions that appear only in the display pattern
shown in FIG. 6b are illuminated in FIG. 7 in red color, and
all overlapping portions are illuminated in FIG. 7 in yellow
color. By comparing the size of the yellow area with
combined sizes of the red and green areas in FIG. 7, the
degree of similarity between the two display patterns may be
readily determined. The display patterns that are very
similar are illuminated mostly in yellow color. The display
patterns that are not similar are illuminated mostly in red
and green colors.
It would be obvious to those skilled in the art that
other types of light sensors, such are photodiodes,
photodarlingtons, phototriacs, photo sensitive silicon
controlled rectifiers, photodetectors, photoresistors,
photoconductive ce].ls, and the like, may be alternatively
used in the preceding circuits.
In FIG. 14a is shown an oscilloscope display 95 on which
exemplary limits 97 Eor a measured waveform in the shape of
a square wave pulse are exhibited in green color. It will be
appreciated that vertical deflection represents amplitude of
measured signal, and horizontal deflection represents time,
in a manner well understood by those skilled in the art. The
limits 97 include start portion limits 97a, rising edge
limits 97b, top portion limits 97c, falling edge limits 97d,
~Ei8~
and end portion limits 97e.
In FIG. 14b is shown a like oscilloscope display 95 on
which an exemplary measured waveform 99, exhibited in red
color, is superimposed on limits 97, exhi'bited in green
color. The portions of measured waveform 99 that are not
within limits 97 are exhibited in red color, and the
portions of measured waveform 99 that are within limits 97
are exhibited, as a result of blending colors, in yellow
color. More specifically, a rounded start portion 99a is
exhibited in red color, to indicate that it is not within
limits 97a, a rising edge portion 99b is exhibited in yellow
color, to indicate that it is within limits 97b, an
overshoot portion 99c is exhibited in red color, to indicate
that it is not within limits 97c, a relatively short top
portion 99d is exhibited in yellow color, to indicate that
it is within limits 97c, a rounded portion 99e is exhibited
in red color, to indicate that it is not within limits 97c,
falling edge portion 99f is ex'hibited in yellow color, to
indicate that it is withi.n limits 97d, and an undershoot
portion 99g is exhi'bited in red color, to indicate that it
is not within limits 97e.
It is contemplated t'hat the principles of the invention
are also applica'ble to numerous diverse types of meas~lring
devices, such are waveform analyzers, spectrum analyzers,
network analyzers, logic analyzers, and the like.
FIG. 15 is a simplified schernatic diagram of a variable
color comparison oscilloscope which includes pairs of red
and green LEDs arranged in rows and columns. The outputs
LED 1, LED 2, LED 3, LED ~, LED 5, LED 6, LED 7, and LED 8
of dot display driver 16b define 8 rows. The outputs Q0, Ql,
19
61!3567
Q2, and Q3 of shift register 53a and outputs Q0, Ql, Q2, and
Q3 of shift register 53b define 8 columns 9 of which only the
first and last columns are shown. Broken lines in FIG. 15
indicate that more display drivers, flip-flops, shift
registers, and pairs of LEDs may be added to provide more
accurate indication of the measured waveform. It would be
obvious that other types of memories and scanning devices
may be readily and effectively used.
The green LEDs 3a, 3b, 3c, 3d, 3e, 3f, 3g, and 3h are
respectively connected, via current limiting resistors 51a,
51b, 51c, 51d, 51e, 51f, 51g, and 51h, to outputs Q0, Ql,
Q2, Q3, Q4, Q5, Q6~ and Q7 of octal flip-flop l9c. In a
similar fashion, green LEDs 3m, 3n, 3p, 3q, 3r, 3s, 3t, and
3u are respectively connected, via current limiting
resistors 51m, 51n, 51p, 51q, 51r, 51s, 51t, and 51u, to
outputs Q0, Ql, Q2, Q3, Qh, Q5, Q6, and Q7 of octal
flip-flop 19d. Data can be selectively written into octal
flip-flops l9c and 19d to exhibit predetermined measurement
limits on oscilloscope display 95a by illuminating certain
of green LEDs 3a to 3u corresponding by their positions to
the limits.
The oscilloscope display 95a is controlled by 4-bit shift
registers 53a and 53b which are adapted for shifting data to
the right by having the output Q3 of shift register 53a
coupled to Shift Right input SR of shift register 53b, by
having the output Q3 of shift register 53b coupled to the
input SR of shift register 53a, and by having their select
inputs S2 coupled to a high logic level, in a manner well
understood by those skilled in the art. The parallel inputs
P0, Pl, P2, and P3 of shift registers 53a and 53b are
i6~7
coupled to a low logic level, except for the Least
significant input P0 of shift register 53a which is coupled
to a high logic level. When a short positive pulse LOAD is
applied to the interconnected select inputs Sl, the data
from the parallel inputs P0, Pl, P2, and P3 are loaded into
shift registers 53a and 53b, appear at their outputs Q0, Ql,
Q2, Q3, and may be serially delivered to the right with each
active transition of clock pulses 29n of a sufficiently high
frequency, when the inputs Sl are returned to a low logic
10 level again. When the frequency of clock pulses 29n is
synchronized with the frequency of a periodically occurring
measured waveform, the columns of oscilloscope display 95a
are progressively scanned in a cyclic sequence for causing
the waveform exhibited on oscilloscope display 95a to be
repeatedly refreshed.
When a high logic level appears at the output Q0 of shift
register 53a, the column of red LEDs 2a, 2b, 2c, 2d, 2e, 2f,
2g, and 2h is enabled. When a high logic level appears at
the output Q3 of shift register 53b, the column of red LEDs
202m, 2n, 2p, 2q, 2r, 2s, 2t, and 2u is enabled. When a high
logic level appears at another output of shift register 53a
or 53b, another column of red LEDs is enabled (not shown).
Although oot shown in the drawings, it would be obvious that
circuits for scaling a measured waveform, synchronization,
triggering, and the like, may be added to a variable color
comparison oscilloscope of the present invention.
A dot display driver 16b, operating in its movable dot
mode, which is achieved by leaving its MODE input open,
fmeasures input waveform Vin applied to its input SIG IN and
30 develops, in accordance with the measured value of the input
21
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signal, a low voltage level at a single one oE its outputs
LED 1 to LED 8, which are respectively couplecl to rows of
red LEDs in oscilloscope disp]ay 95a. The value of resistor
51z determines the brightness of red LEDs 2a to 2u.
Considering as an example the measured value of the input
waveform to be about 1 Volt at the time when the first
column of oscilloscope display 95a is enabled, the output
LED 1 of dot display driver 16b drops to a low voltage
level, and current flows from the output Q0 of shift
register 53a via red LED 2a to the output LED 1 of dot
display driver 16b, causing red LED 2a to illuminate. When
the measured value of the input signal is about 5 Volts at
the time when the last column of oscilloscope display 95a is
enabled, current flows from the output Q3 of shift register
53b via red LED 2r to the output LED 5 of dot display driver
16b, causing red LED 2r to illuminate. It is obvious that a
curve corresponding to the measured waveforrn will appear on
oscilloscope display 95a when the input waveform is
periodically applied to the input Vin. The portions of the
exhibited waveform that are not within the measurement
limits will il:Luminate in red color, and portions of the
exhibited waveform that are within the limits, displayed in
green color, will illuminate, due to internal 'blending in
each pair of LEDs, in yellow color.
Prior art oscilloscopes 'have a problem in requiring
either that the measured waveform 'be applied periodically to
the measuring input, or that the waveform reconstructed from
a memory be repeatedly refreshed on the oscilloscope
display. It is one of the objects of the present invention
to solve such a problem by providing a new type of a memory
~ 6 7
oscilloscope.
FIG. 16 is a simplified schematic diagram of a variable
color comparison memory oscilloscope with an oscilloscope
display 95b, including a large number of display areas 41m
to 41v arranged in rows and columns, which is capable of
retaining and continuously displaying a single measured
waveform, without the need for repeated refreshing. Row
inputs R of display areas 41m to 41v are respectively
coupled in the rows1 Column inputs C of display areas 41m to
41v are respectively coupled in the columns, and Red Data
inputs RD of all display areas 41m to 41v are coupled to a
voltage source -~VCC. The description of the circuit should
be considered together with its associated timing diagram
viewed in FIG. 17.
The Clear inputs CLR of all display areas 41m to 41v are
commonly coupled to a RESET input which is operative to
cause the entire oscilloscope display 95b to be initialized
upon application of a relatively short neg~tive pulse.
During the measurement, the RESET input must be maintained
at a high logic level (not shown).
The limits for a measured waveform may be displayed on
oscilloscope display 95b in green color by activating Green
Data inputs GD, ~ow inputs R, and Column inputs C of certain
i of the display areas 41m to 41v that correspond by their
positions to the limits, while maintaining Red Data inputs
RD of all display areas 41m to 41v at a low logic level (not
shown). The activated display areas will briefly illuminate
in green color and will be stabilized in their illuminated
condition in a manner indicated earlier. The 5reen Data
inputs GD of all display areas 41m to 41v must be maintained
~ 2~E35~7
during subsequent measurements at a low logic level (not
shown).
The oscilloscope display 95b is scanned in a cyclic
sequence by shift register 52 which is adapted for shifting
a single positive pulse to the right with each active
transition of clock pulses 29p, to enable the columns of
oscilloscope display 95b one at a time. When a positive
pulse 29r appears at the output QO of shift register 52, the
Column inputs C of display areas 41t, 41q to 41m are enabled
by a high logic level. When a positive pulse 29s appears at
the output Ql of shift register 52, the Column inputs C of
display areas 41u, 41r to 41n are enabled. When a positive
pulse 29z appears at the output Qn of shift register 52, the
Column inputs C of display areas 41v, 41s to 41p are
enabled.
An analog comparator 14a, which may include an analog to
digital converter, measures input waveform Vin applied to
its input SIG IN and develops, in accordance with the
measured value of the input signal, a high voltage level at
a single one of its outputs OUT 1, OUT 2 to OUT n, which
represent measurement units and which are respectively
coupled to rows of display areas 41m to 41v in oscilloscope
display 95b.
Considering as an example the rneasured value of the input
waveform to be 1 measurement unit at the time when the first
column of oscilloscope display 95b is enabled, the output
OUT 1 of analog comparator 14a rises to a high logic level
to activate row of display areas 41t, 41u to 41v. Since at
that moment only display area 41t has its Column input C at
a high logic level, it briefly illuminates in red color and
24
~ 6~
will be stabilized in its illuminated condition in a manner
previously pointed out.
When the measured value of the input signal is 2
measurement units at the time when the second column of
oscilloscope display 95b is enabled, the output OUT 2 of
analog comparator 14a rises to a high logic level to
activate row of display areas 41q, 41r to 41s. Since at that
moment only display area 41r has its Column input C at a
high logic level, it briefly illuminates in red color and
will be stabilized in its illuminated condition.
It is obvious that a curve corresponding to the measured
waveform will appear on oscilloscope display 95b when the
measurement is completed and will be retained and
continuously displayed thereon until it is reset. The
portions of the exhibited waveform that are not within the
measurement limits will illuminate in red color, and
portions of the exhibited waveform that are within the
limits, displayed in green color on certain of display areas
41m to 41v, will illuminate, due to internal blending in
respective display areas, in yellow color.
The invention may be now briefly summarized. The method
was disclosed of simultaneously exhibiting a measured
waveform and its relation to predetermined limits, on a
single variable color display, by causing the measured
waveform to be exhibited on the display, and by controlling
the color of the exhibited waveform such that its portions
that are within the limits are illuminated in a first color,
and its portions that are outside the limits are illuminated
in a second color.
A comparison oscilloscope was disclosed that comprises a
~2~i~3S~
waveform measuring device, a variable color display for
exhibiting the measured waveform, and color control for
controlling the color of the exhibited waveform in
accordance with its relation to predetermined limits such
that the portions of the measured waveform that are within
the limits are illuminated in a first color, and the
portions of the measured waveform that are outside the
limits are illuminated in a second color. ~ memory
oscilloscope was disclosed which includes a display with a
plurality of variable color display areas capable of
stabilizing their illuminated conditions such that they
maintain their colors.
It would be obvious that numerous modifications can be
made in the construction of the preferred embodiments shown
herein, without departing from the spirit and scope of the
invention as defined in the appended claims. It is
contemplated that the principles of the invention may be
also applied to numerous diverse types of display devices,
such are crt tubes, liquid crystal devices, plasma devices,
and the like.
26
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CORRELATION TABLE
This is a correlation table of reference characters, their
descrip~ions, and examples of commercially available parts.
# DESCRIPTION EXAMPLE
1 display element
2 red LED
3 green LED
4 support
light blending cavity
10 6 light scattering material
7 opaque wall
8 non-inverting buffer 4050
9 resistor
10 variable color analog display
11 variable color bar graph display
13 inclined surface of wall
14 analog comparator
15 display driver
16 bar/dot display driver LM3914
19 octal Elip-flop 74F374
20 color control
21 memory
22 timing device
25 timer NE555
26 14-bit counter 4020
27 capacitor
29 pulse
~6~3~67
# DESCRIPTION EXAMPLE
-
monochromatic 5x7 matrix display
31 variable color 5x7 matrix display
32 support
33 chamber for light emitting diodes
34 aperture
opaque wall
39 buffer 74LS244
41 display area
42 3-input AND gate 74HCll
43 chamber for light emitting diodes
opaque wall
46 opaque chamber wall
47 small chamber
48 phototransistor
49 resistor
pulse
51 resistor
52 shift register
53 4-bit shift register 74HC194
oscilloscope display
97 limits for measured waveform
99 measured waveform
28
